光电子材料钽酸锂晶片化学机械抛光过程研究
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摘要
钽酸锂是近年来随着通讯、信息产业迅速发展而开发并产业化的新型光电子材料。它具有机电耦合系数大、低损耗、高温稳定性、高频性能好等优良的压电、电光和热电性能。目前，钽酸锂晶片的超精密加工技术的研究还很欠缺，实际生产中通常采用化学机械抛光技术进行加工。本论文通过对钽酸锂晶片的化学机械抛光过程的实验研究和抛光运动轨迹的理论分析，研究钽酸锂晶片的抛光加工特性，探讨钽酸锂晶片化学机械抛光机理，系统分析主要工艺参数对化学机械抛光过程的影响规律。
1．采用化学腐蚀实验方法研究抛光液中氧化剂种类和浓度以及抛光液pH值对钽酸锂晶片化学去除的影响。寻找有效的氧化剂及其合适的浓度，确定合理的稳定剂及抛光液的适当pH值。次氯酸钠和过氧化氢是钽酸锂晶片化学机械抛光液中有效的氧化剂，无机碱氢氧化钾是有效的稳定剂，pH值为10适合于钽酸锂晶片化学机械抛光。
2．通过单颗粒金刚石压入钽酸锂晶片光滑表面的划痕实验，研究钽酸锂晶片的机械力学性能和断裂破坏情况，寻找合理的抛光压力。适合钽酸锂晶片化学机械抛光的抛光压力为7.25kPa。
3．理论分析抛光运动的规律并进行抛光轨迹计算机仿真，探求抛光表面形成机理，发现合适的抛光转速和抛光运动参数。适合钽酸锂晶片化学机械抛光的抛光盘转速为n_p=60rpm，工件盘中心到抛光盘中心的距离为e=100mm。
4．通过对钽酸锂晶片的化学机械抛光过程的实验研究，通过测量钽酸锂晶片在不同抛光条件下的表面粗糙度和材料去除率，详细分析了抛光垫材料和状态、抛光压力、抛光盘转速、磨料种类及粒度、抛光液组成等几个因素对抛光表面质量和材料去除率的影响规律。
Tantalum lithium (LiTaO3), a novel single crystal material, developed and industrialized with the development of communication and information industries recently, owns the excellent performances such as high Mechanical-electrical coupling coefficient, lower wear-resistance, excellent high-temperature stability, excellent high-frequency capability, etc. However, researches on tantalum lithium single crystal wafer around world are still lacking. LiTaO3 wafers are machined ususlly by chemical mechnical polishing in industry. Based on the investigation of the mechanical property of tantalum lithium crystal wafer and theory analysis of polishing movement tracks, this thesis discusses its mechanism of CMP, presents its polishing characteristics and analyzes the effects of polishing condition parameters upon CMP.
To find out the effective slurry with suitable type of oxidizer and concentration, chemical etching experiment was applied to the LiTaO3 wafer.the chemical etching effects were analysed by measuring etching rate and X-ray spectrum. The experimental results indicate that for LiTaO3 the oxidizers are NaClO and H2O2, the stabilizator is KOH and the most suitable pH value is 10.
The scratching test was carried out with a single diamond tool to study the removal mechanism of LiTaO3 wafer by load. The AE signals were measured, and the scratched surfaces of LiTaO3 wafers in different conditions were observed by metallography microscope. The results show that the scratched surfaces change from elastic deformation area, plastic deformation area and fracture area with squama and crack. For removing material of LiTaO3 wafer by plastic deformation mode, the polishing pressure should be low than 7.25kPa.
For selecting suitable CMP conditions, the movement of polishing was modelling and simulating. The analysed results show that the reasonable rotating speed np and distance e between workpiece plate center and polishing plate center are 60rpm and 100mm on Ultra-precision surface polishing machine with correction rings,
respectively.
The CMP experiment was carried out systematically on LiTaO3 wafer. The polished surface foughness and material removal rate in different polishing conditions were measured and the effects of polishing pad material and its condition, pressure, rotating speed of the polishing plate, the type and size of abrasive, and the properties of the polishing slurry on the surface routhness and material removal rate were analysed in details.
1．采用化学腐蚀实验方法研究抛光液中氧化剂种类和浓度以及抛光液pH值对钽酸锂晶片化学去除的影响。寻找有效的氧化剂及其合适的浓度，确定合理的稳定剂及抛光液的适当pH值。次氯酸钠和过氧化氢是钽酸锂晶片化学机械抛光液中有效的氧化剂，无机碱氢氧化钾是有效的稳定剂，pH值为10适合于钽酸锂晶片化学机械抛光。
2．通过单颗粒金刚石压入钽酸锂晶片光滑表面的划痕实验，研究钽酸锂晶片的机械力学性能和断裂破坏情况，寻找合理的抛光压力。适合钽酸锂晶片化学机械抛光的抛光压力为7.25kPa。
3．理论分析抛光运动的规律并进行抛光轨迹计算机仿真，探求抛光表面形成机理，发现合适的抛光转速和抛光运动参数。适合钽酸锂晶片化学机械抛光的抛光盘转速为n_p=60rpm，工件盘中心到抛光盘中心的距离为e=100mm。
4．通过对钽酸锂晶片的化学机械抛光过程的实验研究，通过测量钽酸锂晶片在不同抛光条件下的表面粗糙度和材料去除率，详细分析了抛光垫材料和状态、抛光压力、抛光盘转速、磨料种类及粒度、抛光液组成等几个因素对抛光表面质量和材料去除率的影响规律。
Tantalum lithium (LiTaO3), a novel single crystal material, developed and industrialized with the development of communication and information industries recently, owns the excellent performances such as high Mechanical-electrical coupling coefficient, lower wear-resistance, excellent high-temperature stability, excellent high-frequency capability, etc. However, researches on tantalum lithium single crystal wafer around world are still lacking. LiTaO3 wafers are machined ususlly by chemical mechnical polishing in industry. Based on the investigation of the mechanical property of tantalum lithium crystal wafer and theory analysis of polishing movement tracks, this thesis discusses its mechanism of CMP, presents its polishing characteristics and analyzes the effects of polishing condition parameters upon CMP.
To find out the effective slurry with suitable type of oxidizer and concentration, chemical etching experiment was applied to the LiTaO3 wafer.the chemical etching effects were analysed by measuring etching rate and X-ray spectrum. The experimental results indicate that for LiTaO3 the oxidizers are NaClO and H2O2, the stabilizator is KOH and the most suitable pH value is 10.
The scratching test was carried out with a single diamond tool to study the removal mechanism of LiTaO3 wafer by load. The AE signals were measured, and the scratched surfaces of LiTaO3 wafers in different conditions were observed by metallography microscope. The results show that the scratched surfaces change from elastic deformation area, plastic deformation area and fracture area with squama and crack. For removing material of LiTaO3 wafer by plastic deformation mode, the polishing pressure should be low than 7.25kPa.
For selecting suitable CMP conditions, the movement of polishing was modelling and simulating. The analysed results show that the reasonable rotating speed np and distance e between workpiece plate center and polishing plate center are 60rpm and 100mm on Ultra-precision surface polishing machine with correction rings,
respectively.
The CMP experiment was carried out systematically on LiTaO3 wafer. The polished surface foughness and material removal rate in different polishing conditions were measured and the effects of polishing pad material and its condition, pressure, rotating speed of the polishing plate, the type and size of abrasive, and the properties of the polishing slurry on the surface routhness and material removal rate were analysed in details.
引文
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23. P.R. Tavernier, T.Margalith, L.A.Coldren et al. Chemical Mechanical Polishing of Gallium Nitride. Electrochemical and Solid-State Letters. 2002, 5(8): 61-G64
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2．袁巨龙．功能陶瓷的超精密加工技术．哈尔滨工业大学出版社，2000
3．袁哲俊，王先逵．精密和超精密加工技术．机械工业出版社，1999
4．曹丽梅，胡岳华，徐兢．半导体工业中的化学机械抛光技术．湖北化工，2000；(4)：7-9
5. W.A. Gault. Defect Control in Semiconductor. Proceeding of the International Conference on the Science and Technology of Defect Control in Semiconductor, The Yokhama 21st. century Forum, Ed. By Sumine. 1989; 653(9): 17-22
6．江亲瑜，葛宰林，易风．陶瓷材料非接触无损伤电泳抛光机理及影响因素分析．润滑与密封，2001；(6)：2-3，8
7．姚春燕，彭伟，鲁健厦．电泳砂轮加工机理及其试验研究．浙江工业大学学报，1998；26(1)：23-27
8．胡建德，许雪峰，鲁建厦等．电泳技术在脆性材料磨削中的应用．磨床与磨削，1998；(3)：44-46
9．高宏刚，曹健林，陈斌等．浮法抛光原理装置及初步试验．光学精密工程，1995；3(1)：57-61
10. J.L.Yuan, B.H. Iv, X. Lin et al. Research on Abrasives in Chemical Mechanical Polishing Process for Silicon Nitride Balls. Proceedings of the 10th International Manufacturing Conference in China, 2002; Xiamen: PANEL1-096
11．黄文浩，张海军，褚家如等．超光滑表面的离子束抛光与微观形貌检测．仪器仪表学报，1995；16(1)：201-205
12．褚家如，黄文浩．离子束抛光硅片纳米级微观形貌的原子力显微镜研究．电子显微学报，1995；(1)：53-58
13. H.J.Kim, H.Y.Kim, H.D.Jeong et al. Friction and Thermal Phenomena in Chemical Mechanical Polishing. Journal of Materials Processing Technology, 2002(130-131): 334-338
14. X.Lin, J.L.Yuan, B.H.lv et al. Research on Ultraprecision polishing technology for functional ceramics. 6th International Conference on Progress of Machining Technology, 2002; Xi'an: PANEL236-241
15．邢彤，袁巨龙，赵文宏等．铌酸锂晶片的化学机械抛光质量研究．机械工程师，2003：19-21
16. C.J.Tsai, L.Charls, M.H.Tsai et al. Experimental Investigation on Chemical Mechanical Polishing of Wafers with Low-conductivity Dielectrics. ASME International Mechanical Engineering Congress and Exposition, 2001; (1): 135-141
17. D.S.Lim, I.H.Yoon, S.Danyluk et al. Effect of Electric Field on Chemical Mechanical Polishing of Langasite. Wear, 2001; 249:397-400
18．腾林，张广良，任敬心．GGG单晶的胶体软磨料抛光液的制备研究．航空精密制造技术，1994；30(4)：14-16
19．王相田，刘伟，金宇尧．SiO2化学机械抛光奖料的制备与性能研究．华东理工大学学报，1998；24(6)：681-685
20．徐建忠．抛光膏中磨料的解析．电镀与涂饰，2001；20(6)：20-21
21. M.Uday. Fundamental Studies on Silicon Dioxide Chemical Mechanical Polishing. A Dissertation Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirement for the Degree of PhD. 2000, 11
22. G.B.Basim, J.J.Adler, U.Mahajan et al. Effect of Particle Size of Chemical Mechanical Polishing Slurries for Enhanced Polishing with Minimal Defects. Journal of The Electrochemical Society, 2000; 147(9): 3523-3528
23. P.R. Tavernier, T.Margalith, L.A.Coldren et al. Chemical Mechanical Polishing of Gallium Nitride. Electrochemical and Solid-State Letters. 2002, 5(8): 61-G64
24．邢彤，袁巨龙，赵文宏等．铌酸锂晶片CMP过程的工艺参数研究．机械工程师，2003：22-24
25. G.S.Grover, H.Liang, S. Ganeshkumar et al. Effect of Slurry Viscosity Modification on Oxide and Tungsten CMP. Wear, 1998; 214:10-13
26. B.Mullany, G.Byrne. The Effect of Slurry Viscosity on Chemical Mechanical Polishing Of Silicon Wafers. Journal of Materials Processing Technology, 2003; (132): 28-39
27. H.Lu, B.Fookes, Y.Obeng. Quantitative Analysis of Physical and Chemical Changes in CMP Polyurethane Pad Surfaces. Materials Characterization, 2002; 49: 35-44
28. H.Lu, Y.Obeng, K.A.Richardson et al. Applicability of Dynamic Mechanical Analysis for CMP Polyurethane Pad Studies. Materials Characterization, 2002; 49: 177-186
29. B.J.Hooper, G.Byrne, S.Galligan. Pad Conditioning in Chemical Mechanical Polishing. Journal of Materials Processing Technology, 2002; 123:107-113
30. F.Kuchenmeister, U.Schubert, C.Wenzel. SiLK Dielectric Planarization by Chemical Mechanical Polishing. Microelectronic Engineering, 2000; 50:47-52
31. J.McGrath, C.Davis. The Effect of Thin Film Stress Levels on CMP Polish Rates for PETEOS Wafers. Journal of Materials Processing Technology, 2003; 132:16-20
32. W.T.Tseng, C.W.Liu. Effect of mechanical characteristics on the chemical mechanical polishing of dielectric thin films. Thin Solid Films, 1996; 290-291: 458-463
33. J.Seok, C.P.Sukam, et al. Multiscale material removal modeling of chemical mechanical polishing. Wear, 2003; 254:307-320
34．陈俊盼．白宝石晶体加工及检测技术．长春光学精密机械学院硕士学位论文，1998
35. Y.W.Zhao, L.Chang, S.H.Kim. A Mathematical Model for Chemical-Mechanical Polishing based on Formation and Removal of Weakly Bonded Molecular Species. Wear, 2003; 254:332-339
36．夏宗仁，李春忠，崔坤．声表面波器件用Y36°切LiTaO_3晶片表面加工研究．人工晶体学报，2001；30(4)：419-421
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