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The effect of surface modification on the friction and wear

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Available online at Wear264(2008)934–939The effect of surface modification on the friction and wearbehavior of carbon nanofiber-filled PTFE compositesYijun Shi,Xin Feng∗,Huaiyuan Wang,Xiaohua LuCollege of chemical engineering,Nanjing University of Technology,Nanjing210009,PR ChinaReceived13November2006;received in revised form13April2007;accepted22June2007Available online10August2007AbstractCarbon nanofiber(CNF)was treated with HNO3,coupling agent and HNO3followed by coupling agent,respectively.The friction and wear properties of surface-treated CNF were investigated on a ring-on-ring friction and wear tester under dry friction conditions.Scanning electron microscopy(SEM)was utilized to study the worn surfaces of PTFE composites.Experimental results showed that surface modification decreased the friction coefficient of CNF/PTFE composites slightly,and reduced the wear volume loss of the PTFE composites obviously.Among all HNO3 treatments,10min treatment was the best for the improvement of anti-wear properties of PTFE composites.Moreover,the best anti-wear property of the composite was achieved when CNF was treated with HNO3followed by coupling agent treatment,which was about30%lower than that of untreated CNFfilled PTFE under200N load.SEM studies indicated that surface modification could reduce the abrasive wear of CNF/PTFE composites.And the dispersion of CNF in PTFE composites was also improved after the surface modification,especially for the treatment of HNO3followed by coupling agent.©2007Elsevier B.V.All rights reserved.Keywords:Carbon nanofiber;PTFE;Friction;Wear;Composites;Surface modification1.IntroductionPolytetrafluoroethylene(PTFE)is an excellent solid lubri-cant and used commonly in bearing and seals applications[1]. However,PTFE exhibits high wear rate at normal friction con-ditions.Thus a lot of efforts have been continuously made to decrease the wear of PTFE by means of inorganic or organic compound inclusion[2–5].It was found that some micro-scale inorganicfillers showed distinct effect on the friction and wear behavior of PTFE composites,and many researchers had also studied the mechanism offiller action in reducing the wear of PTFE polymer[6,7].Recently,nanometer particles were used asfillers of poly-mer in order to obtain good tribological properties.Li et al. reported thatfilling nanometer ZnO to PTFE could greatly reduce the wear of this polymer and the best anti-wear property was obtained with the composite containing15vol.%nanometer ZnO,but the friction coefficient of nanocomposite was higher ∗Corresponding author.Tel.:+862583588063;fax:+862583588063.E-mail address:xfeng@(X.Feng).than that of the unfilled PTFE[4].Sawyer et al.investigated the tribological properties of PTFE compositesfilled with40nm Al2O3,and they found that the friction coefficient of the com-posite increased slightly compared to the unfilled sample and the wear resistance increased monotonically with increasingfiller concentration[8].Carbonfiber is widely used today as reinforcements for poly-mer matrices in many high-technology applications on account of their high specific tensile modulus,strength and excellent electrical and thermal properties.Carbon nanofiber(CNF)is of great scientific interest since they remain the excellent proper-ties of the conventional carbonfibers and the properties of a material become increasingly size dependent at low dimensions [9].One of the advantages of CNF is an improved processabil-ity and recyclability of thermoplastic nanocomposites.Polymer processing and recycling techniques are not expected to break down thefiller,an issue commonly encountered even in short-fibre reinforced polymers.Furthermore,the small size of the CNF ensures an excellent surfacefinish.By analyzing the literature dealing with nanoparticle-filled polymer composites for tribological applications which are pre-pared by dispersive mixing,it can be estimated that the surface of0043-1648/$–see front matter©2007Elsevier B.V.All rights reserved. doi:10.1016/j.wear.2007.06.014Y.Shi et al./Wear264(2008)934–939935the nanoparticles used have not been pre-treated in most cases. It is well known that the smaller the size offiller particles is,the larger their specific surface area becomes,and the more likely the agglomeration of the particles.If no specific surface treatment is applied beforehand,the unique nano-effect of nanoparticles can-not be fully brought into play[10].Therefore,pre-treatment of nanoparticles before every experiment is necessary.In this work, CNF is treated by HNO3,coupling agent and the combination of them in order to improve its surface properties.The purpose of this work is to study the friction and wear properties of the PTFE compositesfilled with surface modified CNF under dry frictional conditions.Some insights into the fric-tion and wear mechanisms of the PTFE composite are also given. It is expected that this study may be helpful for investigating potential applications of CNF.2.Experiment2.1.MaterialsIn the experiments,the powder of PTFE with an average of 25␮m was supplied by Dupont(7A-J,commercial product)and CNF with the average diameter of200nm were supplied by Key Laboratory for Mesoscopic Chemistry of Ministry of Educa-tion,College of Chemistry and Chemical Engineering,Nanjing University,PR F was prepared from propylene over Ni–Cu catalyst in a conventional horizontal tube furnace.Silane coupling agent KH-550was bought from Nanjing Shuguang Chemical Factory(China).Acetone and HNO3were obtained by Shanghai Chemical Reagent Co.Ltd.(China).Doubly distilled water was used throughout the experiments.2.2.Surface treatment of CNFThe three treatment methods are described as follows: (1)The CNF powder was dipped into50mL69wt.%HNO3for3,6,10,15,20,30and35min,respectively.The treated CNF was collected and was washed to pH7.0by doubly distilled water.Finally the treated CNF was dried at70◦C in a vacuum oven for24h.(2)CNF was added into appreciated quantities of50mL ace-tone solution of KH-550with thoroughly stirring to form homogenous CNF solution.The concentration of KH-550 solution is1.0wt.%.After that,the treated CNF was evapo-rated the solvent at room temperature for8h,subsequently dried at70◦C in a vacuum oven for24h.(3)A combination of the above two methods(HNO3followedby coupling agent treatment).2.3.Preparation of CNF/PTFE compositesThe treated CNF was thoroughly mixed mechanically with the PTFE powder,molded into the blocks by compressing mold-ing under a pressure of70MPa for5min.The fraction of CNF in each composite studied in this paper is2wt.%.Then the PTFE composite blocks were sintered at380◦C for4h in stove and cooled at a rate of40◦C/h back to the room temperature.At last,the sintered blocks were cut into the shape that is shown in Fig.1(c)which is26mm in external diameter,22mm in inner diameter and2.5–3mm in shoulder heightfinally.2.4.Friction and wear testsThe friction and wear tests were conducted on a ring-on-ring friction and wear tester.The contact schematic diagram of frictional parts is shown in Fig.1(a).The counter material wasa steel ring made from45steel(0.42–0.45%C,0.17–0.37%Si,0.58–0.80%Mn,P≤0.040%,S≤0.040%)with a hardness of HRC51.Sliding was performed under dry friction and ambient conditions(temperature:25◦C,humidity50±5%)at sliding velocities of1.4m/s,normal loads of50,100,150and200N. The test time was30min.The friction force was measured with a torque shaft,provided with strain gauges,and the coefficient of friction was calculated from the friction force.Before each test,the surfaces of each specimen and counterpart ring(36mm in external diameter and18mm in inner diameter and8mm in thickness(Fig.1(b)))were polished with800grit paper to a surface roughness of0.2–0.4␮m and were cleaned with acetone. At last,the wear volume loss was calculated out from the loss of each specimen’s weight.In this work,three replicate friction and wear tests were car-ried out so as to minimize data scattering and the average of the three replicate test results was reported.2.5.SEM analysisThe worn surfaces and the cross-sections of PTFE composites were examined with a QUANTA-200SEM.2.6.FT-IR analysisFT-IR spectra were recorded on a Nicolet Nexus B70spec-trometer in the400–4000cm−1wavenumber range.Sixty-four Fig.1.The contact schematic diagram of wear tester:(a)ring-on-ring contact;(b)counterpart ring;(c)sample ring.936Y.Shi et al./Wear264(2008)934–939 scans were taken at a resolution of4cm−1.For testing,the sam-ples werefirst ground to powder in an agate mortar and thenmixed with KBr at a mass ratio of1:500.A hydraulic press wasused to press the resulting mixtures to discs of10mm in diameterat10MPa for3min.3.Results and discussion3.1.RT-IR analysis the surfaces of surface-treated CNFFig.2shows the typical FT-IR spectra of surface-treated CNF.It can be seen from Fig.2that the untreated CNF has absorptionbands,which are found for all the samples,at around3440,1643,1388and1056cm−1.Those at1640and3440cm−1are likelydue to H2O adsorbed in KBr[11].Bands at1388and1056cm−1are attributed to C–O band.However,the effect of adsorbed H2Oon the FT-IR spectra makes it difficult to discriminate the absorp-tion bands of hydroxyl and other groups that contained C–Obands(usually between1000and1400cm−1)[12].After theHNO3oxidation treatment,the sample shows absorption bandat about1730cm−1,which is assigned to the carboxyl group[12].After the coupling agent KH-550treatment,the sampleshows absorption band at about2784and2960cm−1,whichshould be attributed to CH2stretching[13].It confirmed thatthe sample was coated with KH-550successfully.3.2.The effect of treatment time on the friction and wearbehavior of HNO3-treated CNFfilled PTFE compositesThe effect of treatment time on the friction coefficient andwear volume loss of PTFE compositesfilled with HNO3-treatedCNF is given in Figs.3and4,respectively.Fig.3shows that thefriction coefficient decreasesfirstly with the increase of treat-ment time.Then it increases with the increase of treatment timeuntil20min,after that it decreases again.During sliding,CNFis released from the composite and transferred to the interfacebetween mating surfaces.And the CNF in the interface servesas spacers,preventing the direct contact between the two mat-ing surfaces,thereby reducing the friction coefficient[14].TheFig.2.FT-IR spectra of CNF in the range of4000–400cm−1.Fig.3.The effect of treatment time on the friction coefficient of HNO3-treatedCNFfilled PTFE.increase in friction coefficient is due to the accumulation offillers on the worn surfaces of PTFE composites which is similarto the work of many researchers[2,15].It also can be seen from Fig.4that the wear volume loss of the CNF/PTFE composites is greatly affected by the treatmenttime.In other words,the wear volume loss decreases sharplyfirst as the treatment time increases,then it reaches a lowestvalue(5.33mm3)at the10min,which is about20%lower thanthat of untreated CNFfilled PTFE composite.The wear volumeloss gradually turns to increase after the treatment time exceeds10min,although it is still lower than that of the PTFE compositefilled with untreated CNF.These behaviors can be attributed tothe effect of the improving surface properties of CNF after HNO3treatment,which enhances the interaction of CNF and PTFEpolymer.Accordingly,the treated CNFfilled PTFE compositesexhibit lower wear volume loss than that of the untreated CNFfilled PTFE composite.3.3.The effect of treatment method on the friction and wearbehavior of CNF/PTFE compositesThe friction coefficient and the wear volume loss of the PTFE compositesfilled with treated CNF are indicated in Figs.5and6.Fig.4.The effect of treatment time on the wear volume loss of HNO3-treatedCNFfilled PTFE.Y.Shi et al./Wear 264(2008)934–939937Fig.5.The friction coefficient of PTFE composites filled with treated CNF (150N).It should be pointed out here that the HNO 3treatment time used in this section is 10min.It can be seen from Fig.5that the friction coefficient of CNF/PTFE composites is decreased a little after the surface modification of CNF.And the PTFE composite filled the CNF treated with HNO 3followed by coupling agent KH-550shows the lowest friction coefficient.As we can see from Fig.6,the wear volume loss of CNF/PTFE composites is obviously changed after the surface modification of CNF.The PTFE composite filled with HNO 3followed by coupling agent KH-550treated CNF shows the lowest wear volume loss,which is about 27%lower than that of the PTFE filled with untreated CNF.Thus the CNF treated with HNO 3followed by coupling agent KH-550filled PTFE composite is the best from both friction and wear point of view.This indicates that the combi-nation of acid and coupling agent treatment is more effective to improve wear resistance of CNF/PTFE composites than the treatment of HNO 3and silane coupling agent treatment alone.In other words,the combination of acid and coupling agent is more effective to improve the interaction of CNF andPTFE.Fig.6.The wear volume loss of PTFE composites filled with treated CF (150N).Fig.7.The relationship between load and the friction coefficient of PTFE com-posites.3.4.The effect of load on the tribological properties of PTFE composites filled with treated CNFVariations of friction coefficient and wear volume loss with load for CNF/PTFE composites are shown in Figs.7and 8,respectively.It can be seen from Fig.7that the friction coeffi-cient of CNF/PTFE composites decreases with the increase of load.Under all loads,surface treatment decreases the friction coefficient of CNF/PTFE composites slightly.However,as it is shown in Fig.8,the wear volume loss of PTFE composites increases gradually with the increase of load.And,the wear vol-ume loss increases obviously as the load increases above 150N.On the other hand,under any load,the wear volume loss of treated CNF filled PTFE is much lower in comparison with that of the PTFE filled with untreated CNF.In this work,the best anti-wear ability is obtained with the PTFE composite filled with HNO 3followed by coupling agent KH-550treated CNF,which is about 30%lower than that of the untreated CNF filled PTFE under 200N.3.5.SEM analysis the worn surfaces of PTFE composites To understand the effect of the surface modification of CNF on the friction and wear behavior of CNF/PTFEcomposites,Fig.8.The relationship between load and the wear volume loss of PTFE com-posites.938Y.Shi et al./Wear 264(2008)934–939Fig.9.SEM micrographs of worn surfaces of:(A)untreated;(B)HNO 3-treated;(C)HNO 3followed by KH-550treated CNF filled PTFEcomposites.Fig.10.SEM cross-section micrographs of:(A)untreated;(B)HNO 3-treated;(C)HNO 3followed by KH-550treated CNF filled PTFE composites.the worn surfaces of untreated,HNO 3and HNO 3followed by coupling agent treated CNF filled PTFE composites were stud-ied by SEM (Fig.9).Some deep furrows,which were caused by the abrasive friction behavior between the peeled CNF and PTFE composite,appear on the worn surface of untreated CNF filled PTFE (Fig.9(A)).This indicates that abrasive wear is the dominant wear mechanism of untreated CNF filled PTFE.In contrast,less and lower furrows appear on the worn surface of HNO 3-treated CNF filled PTFE composite (Fig.9(B)).More-over,there is only several light nicks on the surface of HNO 3followed by coupling agent treated CNF filled PTFE composite (Fig.9(C)).Namely,the abrasive wear of PTFE is dramatically reduced after the surface modification of CNF,which means that the combination of acid and coupling agent treatment can improve the interaction of CNF and PTFE greatly.It may be attributed to the better bonding between CNF and PTFE.The above investigation is also consistent with the wear volume loss data of PTFE composites.3.6.SEM analysis the cross-sections of PTFE composites In order to explain the effect of surface modification on the microstructure of CNF/PTFE composites,the micrographs of the cross-section of CNT/PTFE composites were obtained by SEM.Fig.10shows a typical SEM image of the cross-section of untreated,HNO 3-treated and HNO 3followed by KH-550treated CNF filled PTFE composites.Due to the Van Der Waals bonding,nanoparticles are well recognized to form agglomer-ated clusters in polymeric matrix during the fabrication process[16].Surface treatment of fillers with appropriate chemicals or coupling agents is useful to improve the PTFE composites interfacial strength and the dispersion of fillers in the compos-ites [17].It is clear that there is inhomogeneous distribution of the filler (Fig.10(A)).The situation for HNO 3-treated CNF filled PTFE composite (Fig.10(B))is much better except several agglomeration with small size,while CNF is well dispersed in the composite after the treatment of HNO 3followed by KH-550(Fig.10(C)).It may be another reason that CNF/PTFE com-posites have better tribological properties after the treatment of surface of CNF.4.Conclusion(1)Under experimental conditions,the coefficient of frictionof CNF/PTFE composites is decreased slightly after the surface treatment of CNF.(2)Among all HNO 3treatments,10min treatment is the bestfor the improvement of anti-wear properties of PTFE com-posites.(3)The best anti-wear property of the composite is achievedwhen CNF is treated with HNO 3followed by coupling agent treatment,which is about 30%lower than that of untreated CNF filled PTFE under the load of 200N.(4)SEM studies indicate that surface modification can reducethe abrasive wear of CNF/PTFE composites obviously.(5)The dispersion of CNF in PTFE composites is also improvedafter the surface modification,especially for the treatment of HNO 3followed by coupling agent.Y.Shi et al./Wear264(2008)934–939939AcknowledgmentsAuthors appreciate the Outstanding Youth Fund of National Natural Science Foundation of PR China(29925616)and National High-tech Research Development Program(863Pro-gram:2003AA333010)and The Tribology Science Fund of National Tribology Laboratory(SKLT02-2).References[1]T.A.Blanchet,F.E.Kennedy,Effects of oscillatory speed and mutualoverlap on the tribological behavior of PTFE and selected PTFE-based self-lubricating Composites,Tribol.Trans.34(1991)327–334.[2]S.Bahadur,D.L.Gong,Formulation of the model for optimal proportionoffiller in polymer for abrasive wear resistance,Wear157(1992)229–243.[3]Z.Z.Zhang,Q.J.Xue,W.M.Liu,W.C.Shen,Friction and wear character-istics of lead and its compoundsfilled polytetrafluoroethylene composites under oil lubricated conditions,Tribol.Int.31(1998)361–368.[4]F.Li,K.Hu,J.Li,B.Zhao,The friction and wear of nanometer ZnOfilledpolytetrafluoroethylene,Wear249(2001)877–882.[5]Z.Zhang,P.Klein,K.Friedrich,Dynamic mechanical properties of PTFEbased short carbonfibre reinforced composites:experiment and artifi-cial neural network prediction,Compos.Sci.Technol.62(2002)1001–1009.[6]X.C.Lu,S.Z.Wen,J.Tong,Y.T.Chen,L.Q.Ren,Wettability,soil adhesion,abrasion and friction wear of PTFE(+PPS)+Al2O3composites,Wear193 (1996)48–55.[7]F.Y.Yan,W.H.Long,Q.J.Xue,L.Wei,The correlation of wear behav-iors and microstructures of graphite-PTFE composites studies by positron annihilation,J.Appl.Polym.Sci.61(1996)1231–1236.[8]W.G.Sawyer,K.D.Freudenberg,P.Bhimaraj,L.S.Schadler,A study onthe friction and wear behavior of PTFEfilled with alumina nanoparticles, Wear254(2003)573–580.[9]B.I.Yakobson,C.J.Brabec,J.Bernholc,Nanomechanics of carbon tubes:Instabilities beyond the linear response,Phys.Rev.Lett.76(1996) 2511–2514.[10]W.K.Asbeck,Dispersion and agglomeration:effects on coating perfor-mance,J.Coat.Technol.45(1987)59–70.[11]G.S.Vicente,P.A.Fernando,D.V.Carlos Javier,P.V.Jose,Formation ofoxygen structures by air activation.A study by FTIR spectroscopy,Carbon 37(1999)1517–1528.[12]J.H.Zhou,Z.J.Sui,J.Zhu,P.Li,D.Chen,Y.C.Dai,W.K.Yuan,Charac-terization of surface oxygen complexes on carbon nanofibers by TPD,XPS and FT-IR,Carbon45(2007)785–796.[13]H.F.Wei,G.H.Hsiue,C.Y.Liu,Surface modification of multi-walled car-bon nanotubes by a sol–gel reaction to increase their compatibility with PMMA resin,Compos.Sci.Technol.67(2007)1018–1026.[14]W.X.Chen,F.Li,G.Han,J.B.Xia,L.Y.Wang,Tribological behavior ofcarbon-nanotube-filled PTFE composites,Tribol.Lett.15(2003)275–278.[15]T.A.Blanchet,F.E.Kennedy,Sliding wear mechanism of polytetrafluo-roethylene(PTFE)and PTFE composites,Wear153(1992)229–243. [16]E.T.Thostenson,C.Y.Li,T.W.Chou,Nanocomposites in context,Compos.Sci.Technol.65(2005)491–516.[17]Y.C.Chen,H.C.Lin,Y.D.Lee,The effects of phenyltrimethoxysilane cou-pling agents on the properties of PTFE/silica composites,J.Polym.Res.11(2004)1–7.。

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表面粗糙度对照表（Surfaceroughnesscomparisontable）

表面粗糙度对照表（Surfaceroughnesscomparisontable）

表面粗糙度对照表（Surface roughness comparison table）United States surface roughness control chartChina's old standard (finish)New Chinese standard (roughness) RaAmerican Standard (micron) RaAmerican Standard (micro inches), RaAt 4Six point threeEightThree hundred and twentySix point three zeroTwo hundred and fiftyAt 5Three point twoFiveTwo hundredFourOne hundred and sixty Three point two zeroOne hundred and twenty-five At 6One point sixTwo point five zeroOne hundredTwoEightyOne point six zeroSixty-threeAt 7Zero point eightOne point two fiveFiftyOneFortyZero point eight zeroThirty-twoAt 8Zero point fourZero point six threeTwenty-fiveZero point five zeroTwentyZero Point Four ZeroSixteenDomestic surface roughness and surface roughness Ra and Rz conversion tables (unit: m)Surface finishAt 1At 2At 3At 4At 5At 6At 7surface RoughnessRaFiftyTwenty-five Twelve point five Six point three Three point two One point six zeroZero point eight zero RzTwo hundredOne hundredFiftyTwenty-fiveTwelve point fiveSix point threeSix point three Surface finishAt 8At 9At 10At 11At 12At 13At 14surfaceRoughnessRaZero Point Four ZeroZero point two zeroZero point one zero zero Zero point zero five zero Zero point zero two five Zero point zero one two -RzThree point twoOne point six zeroZero point eight zeroZero Point Four ZeroZero point two zeroZero point one zero zeroZero point zero five zeroAttached: the roughness of the new and old standard parameters change performance contrast, TR200 roughness instrument according to the new standards change the list of parameters as follows, if there are problems, by the Time Inc responsible for explanation. This table also applies to the company's TR1 series roughness tester. The total number of measurable parameters has not changed after modification, but it is still 13 parameters. It is only displayed in different standards. That is to say, the time roughness instrument product parameter covers the old and new standard parameters! (see table for details)New standard (ISO)Old standard (ISO)ExplainRaRaStandard general parametersRzShown in the Japanese standard JISRzRyParameter definition has been modified. The original Ry is still displayed in the Japanese standard JIS and the German standard DIN.RqRqNo changeRpRpNo changeRvRmSymbol modification, parameter definition unchangedRtNo changeR3zShown in the Japanese standard JIS, the parameter has not changedRmaxIt is shown in German standard DIN and American Standard ANSIRSkSkSymbol modification, definition is not changedRSSSymbol modification, definition is not changedRSmSmSymbol modification, definition is not changedRmrTPIs there a definition of symbol change?Attached: surface roughness international standard processing methodsStandard grade codeSurface roughnessMachining tools (Methods)Requirements for processing materials and hardnessPhotometric descriptionCoarse grind grit sizeFinishing grit sizeDiamond PolishSPI (A1)Ra0.005S13654HRCVery high finish, mirror effectEight thousand four hundred and seven 52HRCSPI (A2)Ra0.01DF-258HRCLow finish, no sandpaperXW-1060HRCSPI (A3)Ra0.02S136300HBLower finish, but no sandpaper718SUPREME300HBSPI (B1)Ra0.05Without brightness, there is a slight 3000# sandpaper patternSPI (B2)Ra0.1Without brightness, there is a slight 2000# sandpaper patternSPI (B3)Ra0.2Without brightness, there is a slight 1000# sandpaper pattern that does not identify the direction of the machined tracesRa0.4Finishing: fine car, finishing milling, grinding and scraping, and hingeThe direction of micro machining tracesRa0.8Finishing: fine car, finishing milling, grinding and scraping, and hingeThe direction of a machined markRa1.6Ra3.2Ra6.3Ra12.5Ra25Ra50The surface roughness is Ra, Rz, Ry, according to GB 3505 excerpt:The surface roughness parameter and its numerical value (Surface Roughness Parameters and their Values) are 3 commonly used ones:轮廓算数平均偏差（RA）——轮廓算术平均偏差；微观不平度十点高度（RZ）——违规点高度；轮廓最大高度（RY）——轮廓最大高度。

激光共聚焦显微镜测量表面粗糙度的探究

激光共聚焦显微镜测量表面粗糙度的探究

分析测试经验介绍 (203 ~ 208)激光共聚焦显微镜测量表面粗糙度的探究廖奕鸥，冯　辉，张重远（中国科学院 金属研究所 分析测试中心，辽宁 沈阳　110016）摘要：介绍了利用激光共聚焦显微镜对不同粗糙度标准样块表面进行粗糙度测量时，各试验参数对测量结果的影响. 对于标准样块，测得的面粗糙度（S a ）符合测量要求（示值误差≤5%），最终确定合理的试验参数. 方法不但具有非接触、高分辨率、测量速度快的特点，同时可以获得被测表面的三维形貌，可以更加直观的对表面进行评价，使激光共聚焦显微镜能够更好的应用于工业材料表面轮廓分析领域.关键词：激光共聚焦显微镜；非接触；三维形貌；面粗糙度中图分类号：O65 文献标志码：B 文章编号：1006-3757（2023）02-0203-06DOI ：10.16495/j.1006-3757.2023.02.010Research on Measuring Surface Roughness with Laser Confocal MicroscopeLIAO Yiou ， FENG Hui ， ZHANG Zhongyuan（Analysis and Testing Center , Institute of Metal Research , Chinese Academy ofSciences , Shenyang 110016, China ）Abstract ：The effect of experimental parameters on the measurement results, using a laser confocal microscope for the roughness measurement on the surface of different roughness standard sample blocks, was introduced. For the standard sample block, the measured surface roughness S a met the measurement requirements (indication error ≤5%), and the reasonable experimental parameters were finally determined. The method not only has the characteristics of non -contact,high resolution and fast measurement speed, but also can obtain the three-dimensional topography of the measured surface, which can more intuitive to evaluate the surface, so that the laser confocal microscope can be applied more favorably in the field of industrial materials profile analysis.Key words ：laser confocal microscope ；non -contact ；three-dimensional topography ；surface roughness激光扫描共聚焦显微镜是近代最先进的细胞生物医学分析仪器之一[1]，其在荧光显微镜成像的基础上加装激光扫描装置，使用紫外光或可见光激光荧光探针，利用计算机进行图像处理[2]. 激光扫描共聚焦显微技术已用于细胞形态定位、立体结构重组、动态变化过程等研究，在形态学、生理学[3]、免疫学、遗传学等分子细胞生物学领域得到广泛应用[4].随着科学技术的快速发展，激光共聚焦扫描显微技术凭借它的特有优势成为一种高分辨率的显微成像技术[5]，但在工业材料领域的应用鲜有报道.工业用激光共聚焦显微镜的工作原理[6]（如图1所示）是采用点光源照射样本，在焦平面上形成一个轮廓分明的小的光点. 该点被照射后发出的反射光被物镜搜集，并沿原照射光路回送到由双色镜构成的分光器. 分光器将光直接送到探测器[7]. 光源和探测器前方都各有一个针孔，分别称为照明针孔和探测针孔. 照明针孔与探测针孔相对于物镜焦平面是共轭的，焦平面上的点同时聚焦于照明针孔和发射针孔，焦平面以外的点被挡在探测针孔之外不能成像，这样得到的共聚焦图像是标本的光学切面，避免了非焦平面上杂散光线的干扰，克服了普通显微镜图像模糊的缺点[8]，把样本分为若干光学断层，逐层扫描成像，层与层之间有较高的纵深分辨率，因此能得到整个焦平面上清晰的共聚焦图像.收稿日期：2023−03−13；　修订日期：2023−05−12.作者简介：廖奕鸥（1994−），女，本科，主要从事材料表面形貌分析工作，E-mail ：.第 29 卷第 2 期分析测试技术与仪器Volume 29 Number 22023年6月ANALYSIS AND TESTING TECHNOLOGY AND INSTRUMENTS June 2023detectorconfocal pinholelaserscannerobjective lensscanning volumefocal plane图1　激光共聚焦显微镜工作原理Fig. 1　Working principle of laser confocal microscope近几年材料表面粗糙度越来越受到重视，科研人员研究了其表面微观形貌的参数. 传统用于表征物体表面二维轮廓的粗糙程度参数R a（线粗糙度）[9]是在一定测量长度l范围内，轮廓上各点至中线距离绝对值的算数平均值. 计算公式如式（1）：其中：l为测量长度，y为各点至中线距离绝对值，x 为测量距离.而用于表征物体表面三维形貌的粗糙程度S a[10]（面粗糙度）则是基于区域形貌粗糙度的评定参数，表示相对于表面的平均面，各点高度差的绝对值的平均值. 计算公式如（2）（3）：其中：µ是平均高度参数，M为测量长度，N为测量高度，k为测量长度M上的点，l为测量高度N上的点，z为物体表面区域轮廓上点到基准面的距离. 它表示区域形貌的算数平均偏差. 利用工业激光共聚焦显微镜对材料表面信息进行采集，获得结构清晰地材料表面三维轮廓图像，通过软件对图像进行处理，可以计算出材料粗糙度（S a或R a）.随着科学技术的快速发展，金属材料表面结构的加工精度越来越高，因此对表面粗糙度测量方法的要求也随之提高. 对于一些软质材料，传统触针式测量不但可能会在测量过程中破坏试样表面结构，影响其金属表面粗糙度结果，而且无法展现材料表面的真实形貌. 现阶段测量要求对材料无损伤产生，同时可以观察材料表面的三维立体形貌，检测速度快、精度高. 非接触式测量方法在现代测量的发展过程中应运而生，成为了获取材料表面微观形貌特征的一种重要检测方法. 利用工业激光共聚焦显微镜对材料表面进行粗糙度测量则是非接触式测量方法之一，其具有测量范围广、分辨率高、速度快等特点. 同时可以获得被测表面的三维形貌图[11]，可以更加直观的对表面进行评价.本文利用激光共聚焦显微镜对6种不同粗糙度的标准样块进行粗糙度测量，讨论了试验过程中各参数[12]对测量结果的影响.1　试验部分1.1　样品试验使用6种不同粗糙度的多刻线样板（购于辽宁北方计量器材有限公司），经专业机构校准后作为待测样品，如图2所示.(a)(b)(c)(d)(e)(f)图2　6种不同粗糙度的标准样块(a) 编号120028，(b) 编号120054，(c) 编号112494，(d) 编号112454，(e) 编号110768，(f) 编号112421 Fig. 2　Surface macromorphology of six standard sampleblocks with different roughness(a) No.120028, (b) No.120054, (c) No.112494, (d) No.112445,(e) No.110768, (f) No.1124211.2　标准样块微观形貌二维曲线图利用接触式表面轮廓仪获得标准样块（编号为112454）的二维曲线图，如图3所示.1.3　仪器和测试条件德国蔡司公司生产的LSM700激光共聚焦显微镜[13]，405 nm固体激光控制器，选用5X、10X、20X、50X、100X物镜进行测试.204分析测试技术与仪器第 29 卷2　结果与讨论2.1　物镜选择将已经校准的6种不同粗糙度的标准样块作为待测样品，分别使用5X 、10X 、20X 、50X 、100X 物镜进行测量. 测量S a 结果如表1所列.由于试验选择的样品为标准样块，其粗糙度范围在0.096~3.072 µm 范围内. 考虑到不同物镜的工作距离及分辨率对应的粗糙度值测量精度有一定的范围，采用不同倍率的物镜进行单个视场扫描并测量，得到粗糙度值如表1所列. 与校准值进行比较发现，在利用激光共聚焦显微镜进行粗糙度测量时，其测量结果准确与否与物镜选择息息相关. 放大倍数越大，物镜景深则越小，需要Z 方向逐层扫描精度也就越高. 因此不同粗糙度样品应采用不同放大倍数进行测量. 针对本试验中样品类型，粗糙度在0.1~0.4 µm 的样品，由于粗糙度较小应选择较高放大倍数50X 物镜进行测量，粗糙度在0.4~3.2 µm 样品应选择放大倍数20X 物镜进行测量.2.2　扫描步长参数在已确定的物镜倍率下，为了更好的确定步进参数对测量结果的影响，分别对粗糙度较小（编号为120028、120054、112494）及粗糙度较大（编号为112454、110768、112421）的标准样块进行试验，S a 结果如表2、3所列.比较表2、3数据发现，由于标准样块形貌属于表 1 6种不同粗糙度的标准样块在不同物镜下测量S a 值Table 1　Measured S a values of six standard sample blocks with different roughness under different objective lenses/µm 物镜大小标准样块编号1200281200541124941124541107681124215X （29.3） 1.879 2.951 2.488 1.862 3.89811.22910X （30.1）0.5270.6560.864 1.783 1.924 4.09820X （30.1）0.1740.3210.5440.836 1.442 2.96850X （46.6）0.1080.2150.4220.7150.909 2.470100X （83.6）0.0620.1290.2300.3240.581 1.495校准值0.0960.2140.4400.8541.4653.072表 2 50X 物镜下3种不同粗糙度的标准样块不同步进参数下测量S a 值Table 2　Measured S a values of three standard sample blocks with different roughness using asynchronous advancingparameters under 50X objective lensNo. 120028No. 120054No. 112494步长 /µm S a/µm 扫描时间/s 步长 /µm S a/µm 扫描时间/s 步长/µm S a/µm 扫描时间/s0.1000.1103710.2000.2152450.5000.422380.0500.1087330.1000.2155200.2000.4221030.0200.111 1 7420.0500.216 1 0130.1000.4262000.0100.1252 5150.0200.2182 3980.0500.427405注：图像扫描像素为512×512，扫描范围为120 µm×120 µm表 3 20X 物镜下3种不同粗糙度的标准样块不同步进参数下测量S a 值Table 3　Measured S a values of three standard sample blocks with different roughness using asynchronous advancingparameters under 20X objective lensNo.112454No.110768No.112421步长/µm S a/µm 扫描时间/s步长/µm S a/µm 扫描时间/s 步长/µm S a/µm 扫描时间/s1.0000.82851 1.500 1.44755 3.0002. 872280.5000.836103 1.000 1.44275 1.500 2.968590.2000.8392540.500 1.440149 1.000 2.962780.1000.8415100.2001.450408″0.5002. 964212注：图像扫描像素为512×512，扫描范围为300 µm×300 µm0.51.01.52.0 2.53.03.54.0−1.01.0H e i g h t /μmLength/mm图3　标准样块（编号为112454）的二维曲线图Fig. 3　2D curve of standard sample block (No. 112454)第 2 期廖奕鸥，等：激光共聚焦显微镜测量表面粗糙度的探究205均匀台阶，且台阶较为平坦. 在固定物镜下，利用激光共聚焦显微镜进行粗糙度的测量时，扫描步长参数设置对标准样块粗糙度值影响不大. 但由于激光共聚焦显微镜的工作原理是逐层扫描成像，因此扫描步长参数设置影响着扫描速率及扫描时间. 当扫描步长参数设置越小时，扫描的层数越多，而激光共聚焦显微镜扫描的层与层之间具有较高的纵深分辨率，所以扫描时间就会越长. 因此为了综合测量结果和测量效率，测量过程中应合理选择扫描步长参数.2.3　三维形貌选择合适物镜，设定合理扫描步长参数的条件下，获得标准样块的三维形貌图如图4所示. 由图4可以看出真实的表面形貌.9.0 μm6.0 μm 3.0 μm 0 μmZ /μm1.3020406080100120120100806040200X /μmY /μm 2.0 μm1.4 μm 0.8 μm 0.4 μm 0 μmZ /μm6.002040608010012012010080604020X /μmY /μm 2.0 μm 1.4 μm 0.4 μm 0 μmZ /μm7020*********120120100806040200X /μmY /μm 25.0 μm 15.0 μm 5.0 μm 0 μmZ /μm11050100150200250300300250200150100500X /μmY /μm0 μm2.0 μm 4.0 μm 6.0 μm 8.0 μm 10.0 μm Z /μm18050100150200250300300250200150100500X /μmY /μm0 μm4.0 μm 8.0 μm 12.0 μm 16.0 μm 20.0 μm Z /μm40050100150200250300300250200150100500X /μmY/μm (a)(b)(c)(d)(e)(f)图4　6种标准样块三维形貌（a ）编号120028，（b ）编号120054，（c ）编号112494，（d ）编号112454，（e ）编号110768，（f ）编号112421Fig. 4　Three dimensional morphology of six standard sample blocks(a) No.120028, (b) No.120054, (c) No.112494, (d) No.112454, (e) No.110768, (f) No.112421206分析测试技术与仪器第 29 卷2.4　重复性在已确定的试验参数下，对编号112454的标准样块重复测试10次，结果如表4所列.由表4可以看出，标样重复测量10次的相对标准偏差（RSD ）均小于5%，重复性良好.表 4 编号112454标准样块重复性试验测量S a 值Table 4　Repeatability test measurement S a value ofstandard sample block No.112454测试次数/次S a/µm RSD/%10.836−0.11920.834−0.35830.8390.23940.836−0.11950.835−0.23960.8400.35870.8410.47880.836−0.11990.8390.239100.834−0.358平均值0.8370.000 23　结论利用激光共聚焦显微镜进行粗糙度测量时，应选择合适的放大倍数和扫描步长参数. 针对本试验中多刻度线样板样品，粗糙度在0.1~0.4 µm 的样品应选择放大倍数50X 物镜进行测量，粗糙度在0.4~3.2 µm 样品应选择放大倍数20X 物镜进行测量. 而扫描步长参数的设置影响测量时间，为了综合测量结果和效率，测量过程中应合理选择扫描步长参数. 利用激光共聚焦显微镜测量材料表面轮廓不但具有非接触、高分辨率、测量速度快的特点，并且在获得相关轮廓参数的同时可以获得被测表面的三维形貌. 本试验对于测量未知样品提供了参考依据，可以更加直观的对材料表面轮廓进行评价.参考文献：孙学俊, 闫喜中, 郝赤. 激光共聚焦扫描显微镜技术简介及其应用[J ]. 山西农业大学学报(自然科学版)，2016，36（1）：1-9, 14. [SUN Xuejun, YAN Xizhong, HAO Chi. Confocal laser scanning micro-scopy, a general guideline and its applications [J ].［ 1 ］Journal of Shanxi Agricultural University (Natural Sci-ence Edition)，2016，36 （1）：1-9, 14.]杨子贤, 王洪星, 易小平. 激光扫描共聚焦显微镜在生物科学研究中的应用[J ]. 热带生物学报，2013，4（1）：99-104. [YANG Zixian, WANG Hongxing, YI Xiaoping. Future prospects of laser scanning confocal microscope in bioscience [J ]. Journal of South China University of Tropical Agriculture ，2013，4 （1）：99-104.]［ 2 ］李玲, 马华玲, 张文娟. 激光共聚焦显微镜在肿瘤研究方面的应用[J ]. 医学信息，2014，27（34）：390. [LI Ling, MA Hualing, ZHANG Wenjuan. Application of laser confocal microscope in tumor research [J ]. Journ-al of Medical Information ，2014，27 （34）：390.]［ 3 ］朱珊珊, 黄志江. 激光扫描共聚焦显微镜在生命科学研究中的应用[J ]. 国外医学(麻醉学与复苏分册)，2005（2）：118-119. [ZHU Shanshan, HUANG Zhiji-ang. Applying laser scanning confocal microscopy in-to life science reseach [J ]. 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[DUAN Yan, GUAN Yuanjun, LAN Xiu jian, et al. Use and management of laserscanning confocal microscopy Zeiss LSM 710[J]. Re-search and Exploration in Laboratory，2012，31 （8）：239-241.]［ 13 ］声明本刊许可中国学术期刊（光盘版）等数字化传播的声明 本刊已许可中国学术期刊（光盘版）、超星全文“域出版”期刊、《中文科技期刊数据库》、《中国终身教育学术研究数据库》、《中国科研仪器案例成果数据库》和《万方数据-数字化期刊群》在其系列数据库产品中以数字化方式复制、汇编、发行、信息网络传播本刊全文. 该社著作权使用费与本刊稿酬一并支付. 作者向本刊提交文章发表的行为即视为同意我社上述声明. 《分析测试技术与仪器》编辑部208分析测试技术与仪器第 29 卷。

可降解锌基骨植入材料及其表面改性研究进展

可降解锌基骨植入材料及其表面改性研究进展

第53卷第2期表面技术2024年1月SURFACE TECHNOLOGY·1·研究综述可降解锌基骨植入材料及其表面改性研究进展冯博玄1，谭晋韵2，裴佳1，袁广银1*（1.上海交通大学 轻合金精密成型国家工程研究中心和金属基复合材料国家重点实验室，上海 200240；2.复旦大学附属华山医院，上海 200040）摘要：医用锌及锌合金有望成为新一代可降解骨植入物材料来促进骨缺损的修复。

概述了可降解医用锌基材料的优势，包括较好的生物安全性和抗菌效果、能促进植入部位周围血管和新骨的生成以及骨相关基因的表达能力。

在此基础上，从基底材料、细胞种类及实验结果等方面系统总结了近年来关于可降解医用锌基材料生物相容性和降解行为的研究。

同时，归纳了可降解医用锌在临床修复骨缺损方面所面临的主要问题和挑战，包括较差的力学性能和较强的细胞毒性。

可降解医用锌较差的力学性能可以通过合金化进行改善，概述了多种新型医用锌合金的力学性能及其生物相容性。

表面改性是提高可降解医用锌基表面生物相容性和调控降解的有效手段。

从基底样品、表面改性手段、使用的细胞或动物模型以及细胞相容性和降解行为等方面，综述了近年来可降解锌基骨植入材料表面改性的研究现状，提出了可降解锌基骨植入材料表面改性目前所面临的难点问题，包括传统表面改性手段加剧了锌离子的释放或在表面改性后可降解医用锌的生物相容性改善功效不足，以及未来的发展方向。

关键词：可降解医用锌；骨植入材料；生物相容性；降解行为；表面改性中图分类号：O61；O62；Q25 文献标志码：A 文章编号：1001-3660(2024)02-0001-14DOI：10.16490/ki.issn.1001-3660.2024.02.001Research Progress of Biodegradable Zinc-based OrthopedicImplant Materials and Their Surface ModificationFENG Boxuan1, TAN Jinyun2, PEI Jia1, YUAN Guangyin1*(1. National Engineering Research Center of Light Alloy Net Forming & State Key Laboratory ofMetal Matrix Composite, Shanghai Jiao Tong University, Shanghai 200240, China;2. Huashan Hospital Affiliated to Fudan University, Shanghai 200040, China)ABSTRACT: In recent years, biodegradable metals, represented by magnesium (Mg), zinc (Zn), and iron (Fe), have received extensive attention from the biomedical and materials fields both domestically and internationally. This article outlined the requirements for ideal bone implant materials, and the advantages of biodegradable metals over other biodegradable materials, including mechanical performance, degradation performance, and biocompatibility. In addition, the degradation mechanism of biodegradable metal materials was summarized. Among them, Mg had been extensively investigated, but its rapid degradation rate lead to compromised mechanical properties and uncontrolled hydrogen evolution. Conversely, the degradation rate of Fe收稿日期：2023-01-04；修订日期：2023-02-25Received：2023-01-04；Revised：2023-02-25基金项目：国家自然科学基金（52130104，51971141）；科技部重点研发专项（2021YFE0204900，2018YFE0115400）Fund：National Natural Science Foundation of China (52130104, 51971141); the National Key Research and Development Program of China (2021YFE0204900, 2018YFE0115400)引文格式：冯博玄, 谭晋韵, 裴佳, 等. 可降解锌基骨植入材料及其表面改性研究进展[J]. 表面技术, 2024, 53(2): 1-14.FENG Boxuan, TAN Jinyun, PEI Jia, et al. Research Progress of Biodegradable Zinc-based Orthopedic Implant Materials and Their Surface Modification[J]. Surface Technology, 2024, 53(2): 1-14.·2·表面技术 2024年1月was notably sluggish, approaching that of non-degradable materials. Zn and Zn alloys, due to their moderate degradation rate, good mechanical properties, and biological safety, were expected to become a new generation of biodegradable bone implant materials to promote bone defect repair. This article summarized the advantages of biodegradable Zn-based materials, including biological safety, antibacterial effects, and the ability to promote the generation of blood vessels and new bone around the implant site, as well as to promote the expression of bone-related genes. Based on this, recent research on the biocompatibility and degradation behavior of biodegradable Zn-based materials was systematically summarized from the aspects of substrate materials, cell types, and experimental results. At the same time, the main problems and challenges faced by the clinical application of biodegradable Zn for repairing bone defects were summarized, including poor mechanical properties and strong cytotoxicity. The poor mechanical properties of biodegradable Zn could be improved through alloying. This article outlined the mechanical properties and biocompatibility of various new medical Zn alloys. The potent cytotoxicity of biodegradable Zn used in medical applications arose from the local accumulation of Zn2+ ion generated during degradation. Zn2+ ion was reported to exhibit biphasic effect on cells. The low concentration of Zn2+ ion could promote the cell adhesion, proliferation, and differentiation. In contrast, the local high concentration of Zn2+ ion resulted from the rapid degradation rate of Zn implants at the initial stage of implantation, and some degradation products such as ZnO and Zn(OH)2 with poor biocompatibility always lead to cytotoxicity and inflammation surrounding the Zn implants, further delaying the regeneration and repair of bone defects. Zn still exhibited slight cytotoxicity after alloying, and surface modification was an effective means to improve the surface biocompatibility and regulate degradation of biodegradable Zn. This article reviewed the current research status of surface modi-fication of biodegradable Zn-based bone implant materials from the aspects of substrate samples, surface modification methods, cell or animal models used, and cell compatibility and degradation behavior, and proposed the current difficulties and future development directions of surface modification of biodegradable Zn-based bone implant materials. Surface modification of biodegradable Zn is still nascent, and there are scarce relevant studies with restricted advancement in the biocompatibility of biodegradable Zn. Traditional surface modification methods have increased the release of Zn2+ ion, resulting in higher cyto-toxicity. Alternatively, the efficacy of improving the biocompatibility of biodegradable Zn through surface modification has been insufficient. The future research direction of biodegradable Zn-based materials should focus more on surface modification methods such as phosphate and its composite coatings, as well as biodegradable polymer coatings.KEY WORDS: biodegradable zinc; bone implant material; biocompatibility; degradation behavior; surface modification每年由机械外伤导致的骨折、由炎症引发的骨组织坏死、由骨肿瘤引起的骨缺损等疾病的患者有数百万人[1-3]。

半导体制造技术

半导体制造技术

Semiconductor Manufacturing Technology半导体制造技术Instructor’s ManualMichael QuirkJulian SerdaCopyright Prentice HallTable of Contents目录OverviewI. Chapter1. Semiconductor industry overview2. Semiconductor materials3. Device technologies—IC families4. Silicon and wafer preparation5. Chemicals in the industry6. Contamination control7. Process metrology8. Process gas controls9. IC fabrication overview10. Oxidation11. Deposition12. Metallization13. Photoresist14. Exposure15. Develop16. Etch17. Ion implant18. Polish19. Test20. Assembly and packagingII. Answers to End-of-Chapter Review QuestionsIII. Test Bank (supplied on diskette)IV. Chapter illustrations, tables, bulleted lists and major topics (supplied on CD-ROM)Notes to Instructors:1)The chapter overview provides a concise summary of the main topics in each chapter.2)The correct answer for each test bank question is highlighted in bold. Test bankquestions are based on the end-of-chapter questions. If a student studies the end-of-chapter questions (which are linked to the italicized words in each chapter), then they will be successful on the test bank questions.2Chapter 1Introduction to the Semiconductor Industry Die:管芯 defective:有缺陷的Development of an Industry•The roots of the electronic industry are based on the vacuum tube and early use of silicon for signal transmission prior to World War II. The first electronic computer, the ENIAC, wasdeveloped at the University of Pennsylvania during World War II.•William Shockley, John Bardeen and Walter Brattain invented the solid-state transistor at Bell Telephone Laboratories on December 16, 1947. The semiconductor industry grew rapidly in the 1950s to commercialize the new transistor technology, with many early pioneers working inSilicon Valley in Northern California.Circuit Integration•The first integrated circuit, or IC, was independently co-invented by Jack Kilby at Texas Instruments and Robert Noyce at Fairchild Semiconductor in 1959. An IC integrates multiple electronic components on one substrate of silicon.•Circuit integration eras are: small scale integration (SSI) with 2 - 50 components, medium scale integration (MSI) with 50 – 5k components, large scale integration (LSI) with 5k to 100kcomponents, very large scale integration (VLSI) with 100k to 1M components, and ultra large scale integration (ULSI) with > 1M components.1IC Fabrication•Chips (or die) are fabricated on a thin slice of silicon, known as a wafer (or substrate). Wafers are fabricated in a facility known as a wafer fab, or simply fab.•The five stages of IC fabrication are:Wafer preparation: silicon is purified and prepared into wafers.Wafer fabrication: microchips are fabricated in a wafer fab by either a merchant chip supplier, captive chip producer, fabless company or foundry.Wafer test: Each individual die is probed and electrically tested to sort for good or bad chips.Assembly and packaging: Each individual die is assembled into its electronic package.Final test: Each packaged IC undergoes final electrical test.•Key semiconductor trends are:Increase in chip performance through reduced critical dimensions (CD), more components per chip (Moore’s law, which predicts the doubling of components every 18-24 months) andreduced power consumption.Increase in chip reliability during usage.Reduction in chip price, with an estimated price reduction of 100 million times for the 50 years prior to 1996.The Electronic Era•The 1950s saw the development of many different types of transistor technology, and lead to the development of the silicon age.•The 1960s were an era of process development to begin the integration of ICs, with many new chip-manufacturing companies.•The 1970s were the era of medium-scale integration and saw increased competition in the industry, the development of the microprocessor and the development of equipment technology. •The 1980s introduced automation into the wafer fab and improvements in manufacturing efficiency and product quality.•The 1990s were the ULSI integration era with the volume production of a wide range of ICs with sub-micron geometries.Career paths•There are a wide range of career paths in semiconductor manufacturing, including technician, engineer and management.2Chapter 2 Characteristics of Semiconductor MaterialsAtomic Structure•The atomic model has three types of particles: neutral neutrons（不带电的中子）, positively charged protons（带正电的质子）in the nucleus and negatively charged electrons（带负电的核外电子） that orbit the nucleus. Outermost electrons are in the valence shell, and influence the chemical and physical properties of the atom. Ions form when an atom gains or loses one or more electrons.The Periodic Table•The periodic table lists all known elements. The group number of the periodic table represents the number of valence shell electrons of the element. We are primarily concerned with group numbers IA through VIIIA.•Ionic bonds are formed when valence shell electrons are transferred from the atoms of one element to another. Unstable atoms (e.g., group VIIIA atoms because they lack one electron) easily form ionic bonds.•Covalent bonds have atoms of different elements that share valence shell electrons.3Classifying Materials•There are three difference classes of materials:ConductorsInsulatorsSemiconductors•Conductor materials have low resistance to current flow, such as copper. Insulators have high resistance to current flow. Capacitance is the storage of electrical charge on two conductive plates separated by a dielectric material. The quality of the insulation material between the plates is the dielectric constant. Semiconductor materials can function as either a conductor or insulator.Silicon•Silicon is an elemental semiconductor material because of four valence shell electrons. It occurs in nature as silica and is refined and purified to make wafers.•Pure silicon is intrinsic silicon. The silicon atoms bond together in covalent bonds, which defines many of silicon’s properties. Silicon atoms bond together in set, repeatable patterns, referred to asa crystal.•Germanium was the first semiconductor material used to make chips, but it was soon replaced by silicon. The reasons for this change are:Abundance of siliconHigher melting temperature for wider processing rangeWide temperature range during semiconductor usageNatural growth of silicon dioxide•Silicon dioxide (SiO2) is a high quality, stable electrical insulator material that also serves as a good chemical barrier to protect silicon from external contaminants. The ability to grow stable, thin SiO2 is fundamental to the fabrication of Metal-Oxide-Semiconductor (MOS) devices. •Doping increases silicon conductivity by adding small amounts of other elements. Common dopant elements are from trivalent, p-type Group IIIA (boron) and pentavalent, n-type Group VA (phosphorus, arsenic and antimony).•It is the junction between the n-type and p-type doped regions (referred to as a pn junction) that permit silicon to function as a semiconductor.4Alternative Semiconductor Materials•The alternative semiconductor materials are primarily the compound semiconductors. They are formed from Group IIIA and Group VA (referred to as III-V compounds). An example is gallium arsenide (GaAs).•Some alternative semiconductors come from Group IIA and VIA, referred to as II-VI compounds. •GaAs is the most common III-V compound semiconductor material. GaAs ICs have greater electron mobility, and therefore are faster than ICs made with silicon. GaAs ICs also have higher radiation hardness than silicon, which is better for space and military applications. The primary disadvantage of GaAs is the lack of a natural oxide.5Chapter 3Device TechnologiesCircuit Types•There are two basic types of circuits: analog and digital. Analog circuits have electrical data that varies continuously over a range of voltage, current and power values. Digital circuits have operating signals that vary about two distinct voltage levels – a high and a low.Passive Component Structures•Passive components such as resistors and capacitors conduct electrical current regardless of how the component is connected. IC resistors are a passive component. They can have unwanted resistance known as parasitic resistance. IC capacitor structures can also have unintentional capacitanceActive Component Structures•Active components, such as diodes and transistors can be used to control the direction of current flow. PN junction diodes are formed when there is a region of n-type semiconductor adjacent to a region of p-type semiconductor. A difference in charge at the pn junction creates a depletion region that results in a barrier voltage that must be overcome before a diode can be operated. A bias voltage can be configured to have a reverse bias, with little or no conduction through the diode, or with a forward bias, which permits current flow.•The bipolar junction transistor (BJT) has three electrodes and two pn junctions. A BJT is configured as an npn or pnp transistor and biased for conduction mode. It is a current-amplifying device.6• A schottky diode is formed when metal is brought in contact with a lightly doped n-type semiconductor material. This diode is used in faster and more power efficient BJT circuits.•The field-effect transistor (FET), a voltage-amplifying device, is more compact and power efficient than BJT devices. A thin gate oxide located between the other two electrodes of the transistor insulates the gate on the MOSFET. There are two categories of MOSFETs, nMOS (n-channel) and pMOS (p-channel), each which is defined by its majority current carriers. There is a biasing scheme for operating each type of MOSFET in conduction mode.•For many years, nMOS transistors have been the choice of most IC manufacturers. CMOS, with both nMOS and pMOS transistors in the same IC, has been the most popular device technology since the early 1980s.•BiCMOS technology makes use of the best features of both CMOS and bipolar technology in the same IC device.•Another way to categorize FETs is in terms of enhancement mode and depletion mode. The major different is in the way the channels are doped: enhancement-mode channels are doped opposite in polarity to the source and drain regions, whereas depletion mode channels are doped the same as their respective source and drain regions.Latchup in CMOS Devices•Parasitic transistors can create a latchup condition(???????) in CMOS ICs that causes transistors to unintentionally（无心的） turn on. To control latchup, an epitaxial layer is grown on the wafer surface and an isolation barrier（隔离阻障）is placed between the transistors. An isolation layer can also be buried deep below the transistors.Integrated Circuit Productsz There are a wide range of semiconductor ICs found in electrical and electronic products. This includes the linear IC family, which operates primarily with anal3og circuit applications, and the digital IC family, which includes devices that operate with binary bits of data signals.7Chapter 4Silicon and Wafer Preparation8z Semiconductor-Grade Silicon•The highly refined silicon used for wafer fabrication is termed semiconductor-grade silicon (SGS), and sometimes referred to as electronic-grade silicon. The ultra-high purity of semiconductor-grade silicon is obtained from a multi-step process referred to as the Siemens process.Crystal Structure• A crystal is a solid material with an ordered, 3-dimensional pattern over a long range. This is different from an amorphous material that lacks a repetitive structure.•The unit cell is the most fundamental entity for the long-range order found in crystals. The silicon unit cell is a face-centered cubic diamond structure. Unit cells can be organized in a non-regular arrangement, known as a polycrystal. A monocrystal are neatly arranged unit cells.Crystal Orientation•The orientation of unit cells in a crystal is described by a set of numbers known as Miller indices.The most common crystal planes on a wafer are (100), (110), and (111). Wafers with a (100) crystal plane orientation are most common for MOS devices, whereas (111) is most common for bipolar devices.Monocrystal Silicon Growth•Silicon monocrystal ingots are grown with the Czochralski (CZ) method to achieve the correct crystal orientation and doping. A CZ crystal puller is used to grow the silicon ingots. Chunks of silicon are heated in a crucible in the furnace of the puller, while a perfect silicon crystal seed is used to start the new crystal structure.• A pull process serves to precisely replicate the seed structure. The main parameters during the ingot growth are pull rate and crystal rotation. More homogeneous crystals are achieved with a magnetic field around the silicon melt, known as magnetic CZ.•Dopant material is added to the melt to dope the silicon ingot to the desired electrical resistivity.Impurities are controlled during ingot growth. A float-zone crystal growth method is used toachieve high-purity silicon with lower oxygen content.•Large-diameter ingots are grown today, with a transition underway to produce 300-mm ingot diameters. There are cost benefits for larger diameter wafers, including more die produced on a single wafer.Crystal Defects in Silicon•Crystal defects are interruptions in the repetitive nature of the unit cell. Defect density is the number of defects per square centimeter of wafer surface.•Three general types of crystal defects are: 1) point defects, 2) dislocations, and 3) gross defects.Point defects are vacancies (or voids), interstitial (an atom located in a void) and Frenkel defects, where an atom leaves its lattice site and positions itself in a void. A form of dislocation is astacking fault, which is due to layer stacking errors. Oxygen-induced stacking faults are induced following thermal oxidation. Gross defects are related to the crystal structure (often occurring during crystal growth).Wafer Preparation•The cylindrical, single-crystal ingot undergoes a series of process steps to create wafers, including machining operations, chemical operations, surface polishing and quality checks.•The first wafer preparation steps are the shaping operations: end removal, diameter grinding, and wafer flat or notch. Once these are complete, the ingot undergoes wafer slicing, followed by wafer lapping to remove mechanical damage and an edge contour. Wafer etching is done to chemically remove damage and contamination, followed by polishing. The final steps are cleaning, wafer evaluation and packaging.Quality Measures•Wafer suppliers must produce wafers to stringent quality requirements, including: Physical dimensions: actual dimensions of the wafer (e.g., thickness, etc.).Flatness: linear thickness variation across the wafer.Microroughness: peaks and valleys found on the wafer surface.Oxygen content: excessive oxygen can affect mechanical and electrical properties.Crystal defects: must be minimized for optimum wafer quality.Particles: controlled to minimize yield loss during wafer fabrication.Bulk resistivity(电阻系数): uniform resistivity from doping during crystal growth is critical. Epitaxial Layer•An epitaxial layer (or epi layer) is grown on the wafer surface to achieve the same single crystal structure of the wafer with control over doping type of the epi layer. Epitaxy minimizes latch-up problems as device geometries continue to shrink.Chapter 5Chemicals in Semiconductor FabricationEquipment Service Chase Production BayChemical Supply Room Chemical Distribution Center Holding tank Chemical drumsProcess equipmentControl unit Pump Filter Raised and perforated floorElectronic control cablesSupply air ductDual-wall piping for leak confinement PumpFilterChemical control and leak detection Valve boxes for leak containment Exhaust air ductStates of Matter• Matter in the universe exists in 3 basic states (宇宙万物存在着三种基本形态): solid, liquid andgas. A fourth state is plasma.Properties of Materials• Material properties are the physical and chemical characteristics that describe its unique identity.• Different properties for chemicals in semiconductor manufacturing are: temperature, pressure andvacuum, condensation, vapor pressure, sublimation and deposition, density, surface tension, thermal expansion and stress.Temperature is a measure of how hot or cold a substance is relative to another substance. Pressure is the force exerted per unit area. Vacuum is the removal of gas molecules.Condensation is the process of changing a gas into a liquid. Vaporization is changing a liquidinto a gas.Vapor pressure is the pressure exerted by a vapor in a closed container at equilibrium.Sublimation is the process of changing a solid directly into a gas. Deposition is changing a gas into a solid.Density is the mass of a substance divided by its volume.Surface tension of a liquid is the energy required to increase the surface area of contact.Thermal expansion is the increase in an object’s dimension due to heating.Stress occurs when an object is exposed to a force.Process Chemicals•Semiconductor manufacturing requires extensive chemicals.• A chemical solution is a chemical mixture. The solvent is the component of the solution present in larger amount. The dissolved substances are the solutes.•Acids are solutions that contain hydrogen and dissociate in water to yield hydronium ions. A base is a substance that contains the OH chemical group and dissociates in water to yield the hydroxide ion, OH-.•The pH scale is used to assess the strength of a solution as an acid or base. The pH scale varies from 0 to 14, with 7 being the neutral point. Acids have pH below 7 and bases have pH values above 7.• A solvent is a substance capable of dissolving another substance to form a solution.• A bulk chemical distribution (BCD) system is often used to deliver liquid chemicals to the process tools. Some chemicals are not suitable for BCD and instead use point-of-use (POU) delivery, which means they are stored and used at the process station.•Gases are generally categorized as bulk gases or specialty gases. Bulk gases are the relatively simple gases to manufacture and are traditionally oxygen, nitrogen, hydrogen, helium and argon.The specialty gases, or process gases, are other important gases used in a wafer fab, and usually supplied in low volume.•Specialty gases are usually transported to the fab in metal cylinders.•The local gas distribution system requires a gas purge to flush out undesirable residual gas. Gas delivery systems have special piping and connections systems. A gas stick controls the incoming gas at the process tool.•Specialty gases may be classified as hydrides, fluorinated compounds or acid gases.Chapter 6Contamination Control in Wafer FabsIntroduction•Modern semiconductor manufacturing is performed in a cleanroom, isolated from the outside environment and contaminants.Types of contamination•Cleanroom contamination has five categories: particles, metallic impurities, organic contamination, native oxides and electrostatic discharge. Killer defects are those causes of failure where the chip fails during electrical test.Particles: objects that adhere to a wafer surface and cause yield loss. A particle is a killer defect if it is greater than one-half the minimum device feature size.Metallic impurities: the alkali metals found in common chemicals. Metallic ions are highly mobile and referred to as mobile ionic contaminants (MICs).Organic contamination: contains carbon, such as lubricants and bacteria.Native oxides: thin layer of oxide growth on the wafer surface due to exposure to air.Electrostatic discharge (ESD): uncontrolled transfer of static charge that can damage the microchip.Sources and Control of Contamination•The sources of contamination in a wafer fab are: air, humans, facility, water, process chemicals, process gases and production equipment.Air: class number designates the air quality inside a cleanroom by defining the particle size and density.Humans: a human is a particle generator. Humans wear a cleanroom garment and follow cleanroom protocol to minimize contamination.Facility: the layout is generally done as a ballroom (open space) or bay and chase design.Laminar airflow with air filtering is used to minimize particles. Electrostatic discharge iscontrolled by static-dissipative materials, grounding and air ionization.Ultrapure deiniozed (DI) water: Unacceptable contaminants are removed from DI water through filtration to maintain a resistivity of 18 megohm-cm. The zeta potential represents a charge on fine particles in water, which are trapped by a special filter. UV lamps are used for bacterial sterilization.Process chemicals: filtered to be free of contamination, either by particle filtration, microfiltration (membrane filter), ultrafiltration and reverse osmosis (or hyperfiltration).Process gases: filtered to achieve ultraclean gas.Production equipment: a significant source of particles in a fab.Workstation design: a common layout is bulkhead equipment, where the major equipment is located behind the production bay in the service chase. Wafer handling is done with robotic wafer handlers. A minienvironment is a localized environment where wafers are transferred on a pod and isolated from contamination.Wafer Wet Cleaning•The predominant wafer surface cleaning process is with wet chemistry. The industry standard wet-clean process is the RCA clean, consisting of standard clean 1 (SC-1) and standard clean 2 (SC-2).•SC-1 is a mixture of ammonium hydroxide, hydrogen peroxide and DI water and capable of removing particles and organic materials. For particles, removal is primarily through oxidation of the particle or electric repulsion.•SC-2 is a mixture of hydrochloric acid, hydrogen peroxide and DI water and used to remove metals from the wafer surface.•RCA clean has been modified with diluted cleaning chemistries. The piranha cleaning mixture combines sulfuric acid and hydrogen peroxide to remove organic and metallic impurities. Many cleaning steps include an HF last step to remove native oxide.•Megasonics(兆声清洗) is widely used for wet cleaning. It has ultrasonic energy with frequencies near 1 MHz. Spray cleaning will spray wet-cleaning chemicals onto the wafer. Scrubbing is an effective method for removing particles from the wafer surface.•Wafer rinse is done with overflow rinse, dump rinse and spray rinse. Wafer drying is done with spin dryer or IPA(异丙醇) vapor dry (isopropyl alcohol).•Some alternatives to RCA clean are dry cleaning, such as with plasma-based cleaning, ozone and cryogenic aerosol cleaning.Chapter 7Metrology and Defect InspectionIC Metrology•In a wafer fab, metrology refers to the techniques and procedures for determining physical and electrical properties of the wafer.•In-process data has traditionally been collected on monitor wafers. Measurement equipment is either stand-alone or integrated.•Yield is the percent of good parts produced out of the total group of parts started. It is an indicator of the health of the fabrication process.Quality Measures•Semiconductor quality measures define the requirements for specific aspects of wafer fabrication to ensure acceptable device performance.•Film thickness is generally divided into the measurement of opaque film or transparent film. Sheet resistance measured with a four-point probe is a common method of measuring opaque films (e.g., metal film). A contour map shows sheet resistance deviations across the wafer surface.•Ellipsometry is a nondestructive, noncontact measurement technique for transparent films. It works based on linearly polarized light that reflects off the sample and is elliptically polarized.•Reflectometry is used to measure a film thickness based on how light reflects off the top and bottom surface of the film layer. X-ray and photoacoustic technology are also used to measure film thickness.•Film stress is measured by analyzing changes in the radius of curvature of the wafer. Variations in the refractive index are used to highlight contamination in the film.•Dopant concentration is traditionally measured with a four-point probe. The latest technology is the thermal-wave system, which measures the lattice damage in the implanted wafer after ion implantation. Another method for measuring dopant concentration is spreading resistance probe. •Brightfield detection is the traditional light source for microscope equipment. An optical microscope uses light reflection to detect surface defects. Darkfield detection examines light scattered off defects on the wafer surface. Light scattering uses darkfield detection to detectsurface particles by illuminating the surface with laser light and then using optical imaging.•Critical dimensions (CDs) are measured to achieve precise control over feature size dimensions.The scanning electron microscope is often used to measure CDs.•Conformal step coverage is measured with a surface profiler that has a stylus tip.•Overlay registration measures the ability to accurately print photoresist patterns over a previously etched pattern.•Capacitance-voltage (C-V) test is used to verify acceptable charge conditions and cleanliness at the gate structure in a MOS device.Analytical Equipment•The secondary-ion mass spectrometry (SIMS) is a method of eroding a wafer surface with accelerated ions in a magnetic field to analyze the surface material composition.•The atomic force microscope (AFM) is a surface profiler that scans a small, counterbalanced tip probe over the wafer to create a 3-D surface map.•Auger electron spectroscopy (AES) measures composition on the wafer surface by measuring the energy of the auger electrons. It identifies elements to a depth of about 2 nm. Another instrument used to identify surface chemical species is X-ray photoelectron spectroscopy (XPS).•Transmission electron microscopy (TEM) uses a beam of electrons that is transmitted through a thin slice of the wafer. It is capable of quantifying very small features on a wafer, such as silicon crystal point defects.•Energy-dispersive spectrometer (EDX) is a widely used X-ray detection method for identifying elements. It is often used in conjunction with the SEM.• A focused ion beam (FIB) system is a destructive technique that focuses a beam of ions on the wafer to carve a thin cross section from any wafer area. This permits analysis of the wafermaterial.Chapter 8Gas Control in Process ChambersEtch process chambers••The process chamber is a controlled vacuum environment where intended chemical reactions take place under controlled conditions. Process chambers are often configured as a cluster tool. Vacuum•Vacuum ranges are low (rough) vacuum, medium vacuum, high vacuum and ultrahigh vacuum (UHV). When pressure is lowered in a vacuum, the mean free path(平均自由行程) increases, which is important for how gases flow through the system and for creating a plasma.Vacuum Pumps•Roughing pumps are used to achieve a low to medium vacuum and to exhaust a high vacuum pump. High vacuum pumps achieve a high to ultrahigh vacuum.•Roughing pumps are dry mechanical pumps or a blower pump (also referred to as a booster). Two common high vacuum pumps are a turbomolecular (turbo) pump and cryopump. The turbo pump is a reliable, clean pump that works on the principle of mechanical compression. The cryopump isa capture pump that removes gases from the process chamber by freezing them.。