金属微器件制作及微电铸铸层结合强度研究
|
摘要
随着MEMS技术的迅速发展,微电子、国防及生物工程等领域对具有一定形状精度和表面质量要求的金属微结构的需求日益迫切。基于UV-LIGA技术的微电铸工艺在制作金属微结构方面也得到了广泛应用。但是在微电铸过程中,铸层与基底或者铸层间界面的结合强度会对金属微结构的制造成型和使用寿命产生很大影响。本课题主要集中于金属微器件的制作工艺,以及如何提高铸层与基底之间或者铸层间界面的结合强度两个方面。研究结果能够为提高微电铸结构制作的成功率和使用的稳定性提供制作工艺参考。
制作了微流控芯片注塑模具型芯。利用电铸后“铸冒”方法结合后续的研磨抛光加工方法改善型芯的高度均匀性,使得同一微模具型芯高度的尺寸精度均控制在±3μm之内,满足了注塑微流控芯片的使用要求。
改善了双层可动微器件的制作工艺。本文对基于UV-LIGA技术的双层可动微结构的制作方法进行了改进,这种方法包括SU-8厚胶光刻工艺、微电铸工艺和牺牲层工艺。改进的工艺方法缩短了微器件的加工周期,节约了制作成本,提高了微器件整体材料一致性。为此类器件的制作提供了一定的工艺借鉴。
研究了电流密度对铸层界面结合强度的影响。本文以不同的电流密度为条件,对微电铸所得实验样片进行划痕实验,结合划痕横向载荷加载曲线与划痕形貌确定了临界载荷的位置,并对各样片的结合强度进行定量计算。分析了铸层的形成机理,讨论了铸层结合强度的影响因素。根据电流密度与过电位的关系以及吸附原子的金属表面扩散理论,对电流密度影响铸层界面结合强度的机理进行了分析,从而获得通过调节电流密度来控制微电铸层界面结合强度的新方法。
研究了预电铸工艺参数的选择对结合强度的影响。实验中选用不同的预电铸电流密度及相应的时间,电铸获得不同的实验样片,并用划痕法测量各样片铸层之间的界面结合强度,以获得最佳的预铸工艺参数,提高了铸层界面间结合强度以及金属微器件制作的成功率,延长了金属微器件的使用寿命。
With the rapid development of MEMS technology, micro structures which have requirements of form accuracy and surface quality, are increasingly demanded in the fields of micro-electronics, national defense and bio-engineering. Micro electroforming based on UV-LIGA technology has been widely applied in the micro structure fabrication. However, in the micro electroforming process, the bond strength of the interface between substrate and electroformed layer affects the success rate of micro structures manufacture and their lives. The primary work of this study mainly concentrates on two aspects:fabrication processes of micro device and micro mold, and the bond strength of the interface between substrate and electroformed layer. The research result provides process reference and theoretical analysis to improve the success rate of micro structures manufacture and prolong their lives.
Micro injection mold was fabricated. Over-plating method combined with the following grinding and polishing processes, which fulfills±3μm error requirement of the electroforming insert in height, was employed to eliminate the nonuniformity of the insert.
The fabrication processes of moveable micro-device with double layers were ameliorated. Based on the UV-LIGA technology, the improved processes consist of SU-8thick photoresist lithography, micro electroforming, no back plate growing process and sacrificial layer process. The new method contracts the process cycle, cuts the cost and keeps the material consistency of the device. The process provides a new option for the fabrication of the devices.
It was studied that current density influences the interfacial bond strength of electroformed layers. Based on micro electroforming experiment, the quantitative measurement of the interfacial bond strength by the scratch test, the effect of current density on interfacial bond strength and its mechanism were investigated. The experimental result indicates that, within the range of chosen current densities, the bond strength keeps a decreasing trend along with the increase of current density. This phenomenon was discussed with the partial discharge theory and the relationship between current density and overpotential.
The influence of pre-electroforming with different parameters on bond strength was studied in the paper. In the experiment different current densities and corresponding time of pre-electroforming were separately applied, obtaining samples sharing different pre-electroformed layers, and the bond strength of the samples was measured with scratch test to obtain optimal pre-electroforming parameters. Applying the parameters can improve the interfacial bond strength of electroformed layers, which will increase the fabrication success rate of micro structures and prolong their life.
制作了微流控芯片注塑模具型芯。利用电铸后“铸冒”方法结合后续的研磨抛光加工方法改善型芯的高度均匀性,使得同一微模具型芯高度的尺寸精度均控制在±3μm之内,满足了注塑微流控芯片的使用要求。
改善了双层可动微器件的制作工艺。本文对基于UV-LIGA技术的双层可动微结构的制作方法进行了改进,这种方法包括SU-8厚胶光刻工艺、微电铸工艺和牺牲层工艺。改进的工艺方法缩短了微器件的加工周期,节约了制作成本,提高了微器件整体材料一致性。为此类器件的制作提供了一定的工艺借鉴。
研究了电流密度对铸层界面结合强度的影响。本文以不同的电流密度为条件,对微电铸所得实验样片进行划痕实验,结合划痕横向载荷加载曲线与划痕形貌确定了临界载荷的位置,并对各样片的结合强度进行定量计算。分析了铸层的形成机理,讨论了铸层结合强度的影响因素。根据电流密度与过电位的关系以及吸附原子的金属表面扩散理论,对电流密度影响铸层界面结合强度的机理进行了分析,从而获得通过调节电流密度来控制微电铸层界面结合强度的新方法。
研究了预电铸工艺参数的选择对结合强度的影响。实验中选用不同的预电铸电流密度及相应的时间,电铸获得不同的实验样片,并用划痕法测量各样片铸层之间的界面结合强度,以获得最佳的预铸工艺参数,提高了铸层界面间结合强度以及金属微器件制作的成功率,延长了金属微器件的使用寿命。
With the rapid development of MEMS technology, micro structures which have requirements of form accuracy and surface quality, are increasingly demanded in the fields of micro-electronics, national defense and bio-engineering. Micro electroforming based on UV-LIGA technology has been widely applied in the micro structure fabrication. However, in the micro electroforming process, the bond strength of the interface between substrate and electroformed layer affects the success rate of micro structures manufacture and their lives. The primary work of this study mainly concentrates on two aspects:fabrication processes of micro device and micro mold, and the bond strength of the interface between substrate and electroformed layer. The research result provides process reference and theoretical analysis to improve the success rate of micro structures manufacture and prolong their lives.
Micro injection mold was fabricated. Over-plating method combined with the following grinding and polishing processes, which fulfills±3μm error requirement of the electroforming insert in height, was employed to eliminate the nonuniformity of the insert.
The fabrication processes of moveable micro-device with double layers were ameliorated. Based on the UV-LIGA technology, the improved processes consist of SU-8thick photoresist lithography, micro electroforming, no back plate growing process and sacrificial layer process. The new method contracts the process cycle, cuts the cost and keeps the material consistency of the device. The process provides a new option for the fabrication of the devices.
It was studied that current density influences the interfacial bond strength of electroformed layers. Based on micro electroforming experiment, the quantitative measurement of the interfacial bond strength by the scratch test, the effect of current density on interfacial bond strength and its mechanism were investigated. The experimental result indicates that, within the range of chosen current densities, the bond strength keeps a decreasing trend along with the increase of current density. This phenomenon was discussed with the partial discharge theory and the relationship between current density and overpotential.
The influence of pre-electroforming with different parameters on bond strength was studied in the paper. In the experiment different current densities and corresponding time of pre-electroforming were separately applied, obtaining samples sharing different pre-electroformed layers, and the bond strength of the samples was measured with scratch test to obtain optimal pre-electroforming parameters. Applying the parameters can improve the interfacial bond strength of electroformed layers, which will increase the fabrication success rate of micro structures and prolong their life.
引文
[1]Kenichi Kataoka, Shingo Kawamura, Toshihiro Itoh, et al. Electroplating Ni micro-cantilevers for low contact-force IC probing[J], Sensors and Actuators A,2003, 103(1-2):116-121.
[2]白基成,郭永丰,刘晋春. 特种加工技术[M]. 哈尔滨：哈尔滨工业大学出版社,2006.
[3]Knowles M R H, Rutterford G, Karnakis D, et al. Micro-machining of metals ceramics and polymers using nanosecond lasers [J]. The International Journal of Advanced Manufacturing Technology,2007,33(1-2):95-102.
[4]张东石,陈烽,刘贺炜等,基于BMP图像边缘跟踪的飞秒激光微加工技术研究[J].科学通报,2009,54(17)：2586-2589.
[5]Fleischer J, Kotschenreuther J. The manufacturing of micro molds by conventional and energy-assisted processes[J]. The International Journal of Advanced Manufacturing Technology,2007,33(1-2):75-85.
[6]Leischer J, Masuzawa T, Schmidt J, et al. New applications for micro-EDM[J]. Journal of Materials Processing Technology,2004,149(1-3):246-249.
[7]Uhlmann E, Piltz S, Doll U. Machining of micro/miniature dies and moulds by electrical discharge machining Recent development[J]. Journal of Materials Processing Technology,2005,167(2-3):488-493.
[8]Stokes C, Palmer P.3D MICRO-FABRICATION PROCESSES:A REVIEW[C]. MEMS Sensors and Actuators, Loughborough:the Institution of Engineering and Technology,2006.
[9]王绍宗,单忠德,吴双峰等, 微细切削技术及微型机床的发展[J].现代制造工程,2010,(2)：142-146.
[10]Schmidt J, Tritschler H. Micro cutting of steel [J]. Microsystem Technologies,2004, 10(3):167-174.
[11]张霖,赵东标,张建明等.中间尺度零件微细铣削加工工艺[J].东南大学学报：自然科学版,2008,38(4)：674-677.
[12]CHAN-PARK M B, ZHANG J, YAN Y H, et al. Fabrication of large SU-8 mold with high aspect ratio microchannels by UV exposure dose reduction[J]. Sensors and Actuators B,2004, 101(1-2):175-182.
[13]V. Seidemann, J. Rade, M. Feldmann, S. Buttgenbach SU8-micromechanical structures with in situ fabricated movable parts[J], Microsystem Technologies,2002 8(4-5):348-350.
[14]Becker E W. Modern electroforming in aerospace application[J]. Plat and Surf Fin, 1991,78(8):11-16.
[15]吴向清,谢发勤.铝上镀铬层结合力的影响因素分析[J].材料保护,2001,34(8)：46-47.
[16]李庆伦,海杰Fe-Mn合金镀层结合强度的研究[J].材料保护,2000,33(2)：5-6.
[17]宋博,温占坤,肖作江等.提高铝合金上电镀镍层结合强度的研究[J].表面技术,2003,32(1)：25-27.
[18]M. Strobel, U. Schmidt, K. Bade, et al. Nucleation and growth of Ni-LIGA layers [J]. Microsystem Technologies,1996,3(3):10-16.
[19]S.J. Jeong, W. Wang, Design and UV-LIGA microfabrication of an electro-statically actuated power relay [J]. Microsystem Technologies,2007,13(3-4):279-286.
[20]H. Ollendorf, D. Schneider. A comparative study of adhesion test methods for hard coating[J]. Surface and Coatings Technology,1999,113(1-2):86-102.
[21]J. Stallard, S. Poulat, D. G. Teer, The study of the adhesion of a TiN coating on steel and titanium alloy substrates using a multi-mode scratch tester[J]. Tribology International,2006,39(2):159-166.
[22]L. Marot, G. Covarel, M.-H. Tuilier, et al. Adhesion of rhodium films on metallic substrates[J]. Thin Solid Films,2008,516(21):7604-7608.
[23]Y. He, I. Apachitei, J. Zhou, et al. The influence of the depth of a plasma nitrided layer in tool-steel substrate on the scratch-resistant properties of PAVCD TiBN coating[J]. Surface&Coating Technology,2007,201(16-17):7036-7042.
[24]Kenneth Holmberg, Anssi Laukkanen, Helena Ronkainen, et al. A model for stresses, crack generation and fracture toughness calculation in scratched Ti-coated steel surface[J]. Wear,2003,254(3-4):278-291.
[25]贾胜芳,MEMS引信保险装置的制作及铸层结合强度研究[D].大连：大连理工大学机械工程学院,2010.
[26]CHUANG Y J, TSENG F G, LIN W K. Reduction of diffraction effect of UV exposure on SU-8 negative thick photoresit by air gap elimination[J]. Microsystem Technologies,2002, 8(4):308-313.
[27]Agrawal D C, aaj R. Measurement of the ultimate shear strength of a metal-ceramic interface[J]. Acta Metallurgica,1989,37(4):1265-1271.
[28]Ting B Y, Winer W Q. A semi-quantitative method for thin film adhesion measurement [J]. Journal of Tribology.1985,107(3):472-477.
[29]郑小玲,游敏.拉伸法测定涂层界面强度的适用性研究[J].粘接技术,2003,24(2)：7-9.
[30]Sa anchez J M. Cross-sectional nanoindentation:a new technique for thin film interfacial adhesion characterization [J]. Acta materialia,1999,47(17):4405-4413.
[31]Era H, Otsubo F, Uchida T, Fukuda S, et al. A modified shear test for adhesion evaluation of thermal sprayed coating[J]. Materials Science and Engineering A,1998, 251(1-2):166-172.
[32]任风章,刘平,翟键等.剥离法测量钛基底和不锈钢基底镍膜的界面结合能[J].材料热处理学报,2005,26(1)：65-69.
[33]何贤昶,沈挺,沈荷生等.用垂直拉伸法测定金刚石薄膜的附着强度[J].机械工程材料,1998,22(5)：7-9.
[34]Bull S J, Berasetegui E G, An overview of the potential of quantitative coating adhesion measurement by scratch test ing[J]. Tribology International,2006,39(2):99-114.
[35]Burnett D J, Rickerby D S. The relationship between hardness and scratch adhesion[J]. Thin Solid Films,1987,154(1-2):403-416.
[36]R. L. Browning, G.-T. Lim, A. Moyse, et al. Quantitative evaluation of scratch resistance of polymeric coatings based on a standardized progressive load scratch test[J]. Surf. Coat. Technol.2006,201(6):2970-2976.
[37]Y. Xie, H. M. Hawthorne, Effect of contact geometry on the failure modes of thin coatings in the scratch adhesion test[J]. Surf. Coat. Technol.,2002,155(2-3):121-129.
[38]P. J. Burnett, D. S. Rickerby, The relationship between hardness and scratch adhession[J]. Thin Solid Films,1987,154(1-2):403-416.
[39]O. Borrero-Lopez, M. Hoffman, A. Bendavid, et al. The use of the scratch test to measure the fracture strength of brittle thin films[J]. Thin Solid Films,2010,518(17): 4911-4917.
[40]M. T. Langier, An energy approach to the adhesion of coatings using the scratch test [J]. Thin Solid Films,1984,117(4):243-249.
[41]S. J. Bull, D. S. Rickerby, A. Matthews, et al. The use of scratch adhesion test ing for the determination of interfacial adhesion:the importance of friction drag[J]. Surf. Coat. Technol.,1988,36(1-2):503-517.
[42]安茂忠,电镀理论与技术[M].哈尔滨：哈尔滨工业大学出版社,2004.
[2]白基成,郭永丰,刘晋春. 特种加工技术[M]. 哈尔滨：哈尔滨工业大学出版社,2006.
[3]Knowles M R H, Rutterford G, Karnakis D, et al. Micro-machining of metals ceramics and polymers using nanosecond lasers [J]. The International Journal of Advanced Manufacturing Technology,2007,33(1-2):95-102.
[4]张东石,陈烽,刘贺炜等,基于BMP图像边缘跟踪的飞秒激光微加工技术研究[J].科学通报,2009,54(17)：2586-2589.
[5]Fleischer J, Kotschenreuther J. The manufacturing of micro molds by conventional and energy-assisted processes[J]. The International Journal of Advanced Manufacturing Technology,2007,33(1-2):75-85.
[6]Leischer J, Masuzawa T, Schmidt J, et al. New applications for micro-EDM[J]. Journal of Materials Processing Technology,2004,149(1-3):246-249.
[7]Uhlmann E, Piltz S, Doll U. Machining of micro/miniature dies and moulds by electrical discharge machining Recent development[J]. Journal of Materials Processing Technology,2005,167(2-3):488-493.
[8]Stokes C, Palmer P.3D MICRO-FABRICATION PROCESSES:A REVIEW[C]. MEMS Sensors and Actuators, Loughborough:the Institution of Engineering and Technology,2006.
[9]王绍宗,单忠德,吴双峰等, 微细切削技术及微型机床的发展[J].现代制造工程,2010,(2)：142-146.
[10]Schmidt J, Tritschler H. Micro cutting of steel [J]. Microsystem Technologies,2004, 10(3):167-174.
[11]张霖,赵东标,张建明等.中间尺度零件微细铣削加工工艺[J].东南大学学报：自然科学版,2008,38(4)：674-677.
[12]CHAN-PARK M B, ZHANG J, YAN Y H, et al. Fabrication of large SU-8 mold with high aspect ratio microchannels by UV exposure dose reduction[J]. Sensors and Actuators B,2004, 101(1-2):175-182.
[13]V. Seidemann, J. Rade, M. Feldmann, S. Buttgenbach SU8-micromechanical structures with in situ fabricated movable parts[J], Microsystem Technologies,2002 8(4-5):348-350.
[14]Becker E W. Modern electroforming in aerospace application[J]. Plat and Surf Fin, 1991,78(8):11-16.
[15]吴向清,谢发勤.铝上镀铬层结合力的影响因素分析[J].材料保护,2001,34(8)：46-47.
[16]李庆伦,海杰Fe-Mn合金镀层结合强度的研究[J].材料保护,2000,33(2)：5-6.
[17]宋博,温占坤,肖作江等.提高铝合金上电镀镍层结合强度的研究[J].表面技术,2003,32(1)：25-27.
[18]M. Strobel, U. Schmidt, K. Bade, et al. Nucleation and growth of Ni-LIGA layers [J]. Microsystem Technologies,1996,3(3):10-16.
[19]S.J. Jeong, W. Wang, Design and UV-LIGA microfabrication of an electro-statically actuated power relay [J]. Microsystem Technologies,2007,13(3-4):279-286.
[20]H. Ollendorf, D. Schneider. A comparative study of adhesion test methods for hard coating[J]. Surface and Coatings Technology,1999,113(1-2):86-102.
[21]J. Stallard, S. Poulat, D. G. Teer, The study of the adhesion of a TiN coating on steel and titanium alloy substrates using a multi-mode scratch tester[J]. Tribology International,2006,39(2):159-166.
[22]L. Marot, G. Covarel, M.-H. Tuilier, et al. Adhesion of rhodium films on metallic substrates[J]. Thin Solid Films,2008,516(21):7604-7608.
[23]Y. He, I. Apachitei, J. Zhou, et al. The influence of the depth of a plasma nitrided layer in tool-steel substrate on the scratch-resistant properties of PAVCD TiBN coating[J]. Surface&Coating Technology,2007,201(16-17):7036-7042.
[24]Kenneth Holmberg, Anssi Laukkanen, Helena Ronkainen, et al. A model for stresses, crack generation and fracture toughness calculation in scratched Ti-coated steel surface[J]. Wear,2003,254(3-4):278-291.
[25]贾胜芳,MEMS引信保险装置的制作及铸层结合强度研究[D].大连：大连理工大学机械工程学院,2010.
[26]CHUANG Y J, TSENG F G, LIN W K. Reduction of diffraction effect of UV exposure on SU-8 negative thick photoresit by air gap elimination[J]. Microsystem Technologies,2002, 8(4):308-313.
[27]Agrawal D C, aaj R. Measurement of the ultimate shear strength of a metal-ceramic interface[J]. Acta Metallurgica,1989,37(4):1265-1271.
[28]Ting B Y, Winer W Q. A semi-quantitative method for thin film adhesion measurement [J]. Journal of Tribology.1985,107(3):472-477.
[29]郑小玲,游敏.拉伸法测定涂层界面强度的适用性研究[J].粘接技术,2003,24(2)：7-9.
[30]Sa anchez J M. Cross-sectional nanoindentation:a new technique for thin film interfacial adhesion characterization [J]. Acta materialia,1999,47(17):4405-4413.
[31]Era H, Otsubo F, Uchida T, Fukuda S, et al. A modified shear test for adhesion evaluation of thermal sprayed coating[J]. Materials Science and Engineering A,1998, 251(1-2):166-172.
[32]任风章,刘平,翟键等.剥离法测量钛基底和不锈钢基底镍膜的界面结合能[J].材料热处理学报,2005,26(1)：65-69.
[33]何贤昶,沈挺,沈荷生等.用垂直拉伸法测定金刚石薄膜的附着强度[J].机械工程材料,1998,22(5)：7-9.
[34]Bull S J, Berasetegui E G, An overview of the potential of quantitative coating adhesion measurement by scratch test ing[J]. Tribology International,2006,39(2):99-114.
[35]Burnett D J, Rickerby D S. The relationship between hardness and scratch adhesion[J]. Thin Solid Films,1987,154(1-2):403-416.
[36]R. L. Browning, G.-T. Lim, A. Moyse, et al. Quantitative evaluation of scratch resistance of polymeric coatings based on a standardized progressive load scratch test[J]. Surf. Coat. Technol.2006,201(6):2970-2976.
[37]Y. Xie, H. M. Hawthorne, Effect of contact geometry on the failure modes of thin coatings in the scratch adhesion test[J]. Surf. Coat. Technol.,2002,155(2-3):121-129.
[38]P. J. Burnett, D. S. Rickerby, The relationship between hardness and scratch adhession[J]. Thin Solid Films,1987,154(1-2):403-416.
[39]O. Borrero-Lopez, M. Hoffman, A. Bendavid, et al. The use of the scratch test to measure the fracture strength of brittle thin films[J]. Thin Solid Films,2010,518(17): 4911-4917.
[40]M. T. Langier, An energy approach to the adhesion of coatings using the scratch test [J]. Thin Solid Films,1984,117(4):243-249.
[41]S. J. Bull, D. S. Rickerby, A. Matthews, et al. The use of scratch adhesion test ing for the determination of interfacial adhesion:the importance of friction drag[J]. Surf. Coat. Technol.,1988,36(1-2):503-517.
[42]安茂忠,电镀理论与技术[M].哈尔滨：哈尔滨工业大学出版社,2004.