摘要
化学机械抛光(CMP)是目前半导体制造中唯一能够实现全局平坦化的加工技术,它广泛应用于单晶硅衬底和金属互连层结构的层间平坦化等加工。然而,传统CMP技术还存在一定的缺点和局限性,如工艺稳定性差、效率低、成本高、环境污染严重等。固结磨料化学机械抛光技术应运而生,它能够从根本上解决游离磨料抛光工艺的不足,提高加工效率,改善加工工件的表面质量,减少废液处理压力,保护环境和降低生产成本。本文从固结磨料抛光垫制备着手,通过对抛光垫基体性能影响因素的分析,探索其对工件材料去除率以及加工后工件表面质量的影响,并获得高材料去除率和高加工精度的固结磨料抛光垫。
本文主要工作和取得成果如下:
1)提出了抛光垫基体特性(溶胀率、硬度)的评价方法,运用正交试验方法分析了各组分对基体特性的影响。结果表明:TMPTA对基体溶胀率与湿态硬度影响特别显著,PUA对基体湿态硬度影响特别显著。
2)介绍了两种固结磨料抛光垫的制备方法,并对其抛光性能进行了比较研究。以2.5~5μm金刚石为磨粒,制备了八种固结磨料抛光垫对K9光学玻璃和硅片进行探索性抛光试验。结果表明:低的溶胀率有助于提高工件的材料去除率和降低加工后工件的表面粗糙度;较低的湿态硬度能够获得较低的表面粗糙度和高的材料去除率。
3)采用特定溶胀率和湿态硬度的CeO2固结磨料抛光垫对硅片、手机面板玻璃以及K9光学玻璃进行抛光试验,并与传统游离磨料抛光工艺进行比较,结果表明:目前阶段,CeO2固结磨料抛光垫对硅片的材料去除率极低,对K9光学玻璃和手机面板玻璃的材料去除率亦不如游离磨料抛光,但表面质量要稍好。
4)比较研究了金刚石固结磨料与游离磨料抛光硅片等材料,结果表明:5~10μm金刚石固结磨料抛光垫抛光硅片的材料去除率是游离磨料抛光的3倍,同时实现了自修整功能;固结磨料抛光对磨粒粒径大小的依赖没有游离磨料抛光那么强,采用2.5~5μm与5~10μm的金刚石磨料抛光,能够获得同样好的工件表面质量;并从加工后工件表面的划痕出发分析了两种抛光工艺的抛光特点。
Chemical Mechanical Polishing (CMP) is the only technique capable of achieving high level of global planarization, and is widely used in manufacturing monocrystalline silicon wafer and the metal interconnection which is used in the multi-level wiring process. However, conventional CMP technology has some disadvantages and limitations, such as worse process stability, low-level efficiency, high cost and severe environmental pollution. Fixed-abrasive chemical mechanical polishing technology comes into being, which enables to resolve the defects of abrasive polishing process, raise efficiency, improve the surface quality of work pieces, reduce the pressure of liquid waste disposal, protect the environment and reduce production cost. The study commences on the preparation of fixed-abrasive polishing pad, seeks its influence on material removal rate as well as the processed surface quality through the analysis of the performance influencing factors on the polishing pad matrix, and gets fixed-abrasive polishing pad with high material removal rate and high machining accuracy.
The main work and the achievements are as follows:
1) The swelling rate and the hardness are selected as the evaluation criteria of the polishing pad matrix properties. The influence of each component on the characteristics of matrix is analyzed based on orthogonal test. It shows that the ratio of TMPTA influenced the swelling rate and the wet hardness particularly obvious, and the ratio of PUA influenced the wet hardness particularly obvious.
2) The method of two kinds of polishing pad preparation is introduced, and their polished performances are compared. Choosing eight kinds of 2.5~5μm diamond fixed-abrasive polishing pad, the polishing experiments on the K9 optical glass and the silicon wafer are studied. The results show that lower swelling rate benefits to improve the material removal rate and reduces the processed surface roughness, and lower wet hardness benefit to get lower surface roughness value and higher material removal rate.
3) Choosing ceria fixed-abrasive polishing pad with specific swelling rate and wet hardness, polishing experiments on silicon wafer, mobile phone panel glass and K9 optical glass are studied to compare with conventional abrasive polishing. At the present stage, the results show that ceria fixed-abrasive polishing pad has a extremely low material removal rate on the silicon wafer, and a lower material removal rate on K9 optical glass and mobile phone panel glass than abrasive polishing ,but better surface quality.
4) Studying the polishing of silicon wafer and other material by diamond fixed-abrasive polishing and abrasive polishing, it shows that the material removal rate of silicon wafer polished with 5~10μm diamond fixed-abrasive polishing pad is three times as much as that polished with conventional polishing and the function of self-conditioning is working on the process of fixed-abrasive polishing. The particle size plays a weaker role in fixed-abrasive polishing than abrasive polishing, so the work pieces could get the same good surface quality with 2.5~5μm and 5~10μm diamond abrasive. And the characteristic of the two polishing process is analyzed from the scratches of the processed work pieces surface.
引文
[1] Gartner:2008年全球IC产业的成长率预测值调升为4.6%. http://article.sichinamag.com/20 08-06/200865103816.htm.
[2] iSuppli乐观估计全球半导体市场2009年将触底反弹. http://article.sichinamag.com/2008-10/ 20081015100631.htm.
[3] C. Davies.用于汽车的高亮度LED照明.电子产品世界[J], 2007(10):72~76.
[4]崔澎. 2007年LED市场将以2位数增长.电子产品世界[J], 2007(12):38~40.
[5] 2006年全球手机显示屏市场销售额达28亿美元. http://mep128.mofcom.gov.cn/mep/xwzx/cyz x/161519.asp.
[6] iSuppli预计08年全球将售出5.73亿个硬盘. http://www.phontol.com/20080730_298113.html.
[7]晓晨.国家点火装置概况[J].激光与光电子学进展, 2003, 40(9):2~3.
[8]国家长期科学和技术发展规划纲要——制造业部分[J].机械工业标准化与质量, 2006(03):6~7
[9]刘学璋,王柏春,许向阳,等.硬盘微晶玻璃基板的纳米金刚石抛光[J].微纳电子技术, 2007,44(3):155~158.
[10] M. Kulawski. Polishing of Ground Silicon Wafer with Fixed Abrasive Pad[C]. Proc of the 9th CMP User Meeting, Neuss, Germany, 2002,10.
[11] J.D. Yang, C.L. Tian, C.X. Wang. Nanometer lapping technology at high speed[J]. Sci China Ser E-Tech Sci, 2007, 50(1):27~38.
[12] J.D. Yang, X.H. Wen, Y.Q. Zhu, et al. Discussing on solid abrasive lapping path[J]. Chinese Journal of Mechanical Engineering, 1997, 10(2):101~105.
[13]杨建东,朱艳秋,任长根,等.机械密封研磨模具均匀磨损探讨[J].农业机械学报,1998, 29(1):108~112.
[14] B.H. Lv, J.L. Yuan, Y.X. Yao, et al. Study on fixed abrasive lapping technology for ceramic balls[J]. Materials Science Form, 2006, 532-533:460~463.
[15] W.H. Huang, S. Tamilmani, C. Anderson, et al. Material Removal and Particulate Generation During Abrasion of Copper Films Using a Fixed Abrasive Pad[J]. IEEE Transactions on Semiconductor Manufacturing, 2004, 17(4):525~530.
[16] P.V.D. Velden, Chemical mechanical polishing with fixed abrasives using different subpads to optimize wafer uniformity[J]. Microelectronic Engineering, 2000, 50(4):41~16.
[17] A.Simpson, L. Economilks, F-F. Jamin, et al. Fixed abrasive technology for STI CMP on a web format tool[C]. Mat. Res. Soc. Symp. Proc, 2001, 671:1~9.
[18] L.Economikos, F-F.Jamin, A.Simpson, et al. STI Planarization Using Fixed Abrasive Technology[J]. Future Fab International, 2006, 12(6):217~220.
[19] J.Gagliardi, R.Webb, C.Rueb. Fixed abrasive and selective chemistries: some real advantages for direct STI CMP[C]. Proc. CMP-MIC, 2002:288~290.
[20] J.Gagliardi, S.Paul, 3M Company. Fixed Abrasive Direct STI CMP Allows Elimination of the Conventional Subpad Compromise for Edge NU and WID Ranges[C]. Proc. of the 204 Elec. Chem. Soc., 2003:149~156.
[21] V.H.Nguyen, A.J.Hof, H.V. Kranenburg, et al. Copper chemical mechanical polishing using a slurry-free technique[J]. Microelectronic Engineering, 2001, 55(4):305~312.
[22] B. Lee, D.S. Boning, L. Economikos. A Fixed Abrasive CMP Model[C]. Proc. of CMP-MIC, 2001:395~402.
[23] J.Y Choi, H.D. Jeong. A study on polishing of molds using hydrophilic fixed abrasive pad [J]. International Journal of Machine Tools & Manufacture 2004, 44(11):1163~1169.
[24] H. Kim, H. Kim, H. Jeong, et al. Self-conditioning of encapsulated abrasive pad in chemical mechanical polishing[J]. Journal of Materials Processing Technology, 2003, 142(3):614~618.
[25]苏建修. IC制造中硅片化学机械抛光材料去除机理研究[博士学位论文].大连:大连理工大学, 2006.
[26]宋晓岚,李宇焜,江楠,等.化学机械抛光技术研究进展[J].化工进展, 2008, 27(1):26~31.
[27] Peter.中国集成电路产业发展的进与退[J].半导体技术, 2007, 32(6):550~551.
[28]张锦,孙丽丽.高品质石英材料的生产与应用[J].半导体行业, 2008(05):62~63.
[29]孙玉利,左敦稳,朱永伟,等.工件旋转式磨削大直径硅片技术的研究进展[J].宇航材料工艺, 2006, 36(5):12~16.
[30]李勇东.最新硅材料配方设计、生产技术、工艺流程与质量检测及标准规范实务全书.北京:当代中国音像出版社[M], 2004,8.
[31]翁寿松.推动半导体产业链发展的两大轮子[J].半导体技术, 2004, 29(5):25~26.
[32]孙宏伟.叠层芯片封装技术与工艺探讨[J].电子工业专用设备, 2006, 35(5):65~74.
[33]陆国权.世界电子元件现状与发展趋势[J].电子产品与技术, 2004(4): 82~84.
[34]龙乐.多芯片封装技术以及应用[J].电子与封装, 2006, 6(1):12~15.
[35]李军.硬脆材料超精密加工关键技术研究[博士学位论文].北京:中国科学理化技术研究所, 2007
[36]王永光,赵永武.基于分子量级的化学机械抛光材料去除机理[J].半导体学报, 2008, 28(2):308~312.
[37]雷红,雒建斌,马俊杰.化学机械抛光(CMP)技术的发展、应用及存在问题[J].润滑与密封, 2002(4):73~76.
[38]郭东明,康仁科,苏建修,等.超大规模集成电路制造中硅片平坦化的未来发展[J].机械工程学报, 2003, 39(10):100~105.
[39]刘玉玲,檀柏梅,张楷亮编.超大规模集成电路衬底材料性能及加工测试技术工程[M].冶金工业出版社, 2002,8.
[40] J.M. Steigerwald, S.P. Murka, R.J. Gutmann, et al. Chemical process in the chemical mechanical polishing of copper[J], Material Chemistry and Physics, 1995, 41(3):217~228.
[41] P.B. Zantye, A. Kumar, A.k. Sikder. Chemical mechnical planarization for microelectronics applications[J]. Material Science and Engineering, 2004, 45(3-6):89~220.
[42] C-H. Cho, S-S. Park, Y. Ahn. Three-dimensional wafer scale hydrodynamic modeling for chemical mechanical polishing[J]. Thin Solid Films, 2001, 389(1-2):254~260.
[43]胡伟,魏昕,谢小柱,等. CMP抛光半导体晶片中抛光液的研究[J].金刚石与磨料磨具工程, 2006, (6):78~80.
[44] B.J. Hooper, G. Byrne. S. Galligan. Pad conditioning in chemical mechnical polishing[J]. Journal of Materials Processing Technology, 2002, 123(1):107~113.
[45]刘波.抛光垫表面构造和组织对CMP影响效果的研究[硕士学位论文].大连:大连理工大学工学, 2006,12.
[46]杨建东,田春林,金海峰.固着磨料研磨对工件表面残余应力的影响[J].中国表面工程, 2002, 15(4):37~38.
[47]苏建修,康仁科,郭东明.超大规模集成电路制造中硅片化学机械抛光技术分析[J].半导体技术, 2003, 8(10):27~32.
[48] E. Hwang. Design Rules for the Development of a New-Concept Pad[J], Solid State Technol, 1999, 17(4):53~58.
[49]陈芳,郑耀臣,宋永东.丙烯酸聚氨酯清漆的层间附着力[J].涂料工业, 2004, 34(7):47~49.
[50]刘楠楠,杨建军,张建安,等.纳米改性水性聚氨酯的研究进展[J].中国皮革, 2008, 37(19): 48~52.
[51]宋晓岚,王海波,吴雪兰,等.纳米颗粒分散技术的研究与进展[J].化工进展, 2005, 24(1): 47~52.
[52]沈建良.微电子制造用固结磨料抛光垫的制备探索研究[硕士学位论文].南京:南京航空航天大学, 2008,3.
[53]王桃芬,张循利,时宝国.抛光参量对抛光光学元件亚表层的影响[J].航空精密制造技术, 2008, 44(1):25~27.
[54]张楷亮. CMP纳米抛光液及抛光工艺相关技术研究[博士后研究工作报告].上海:中国科学院上海微系统与信息技术研究所, 2006,1.
[55]胡建东.铈基抛光粉的制备及其在CMP中的应用[博士学位论文].南昌:南昌大学, 2007,6.
[56]狄卫国.甚大规模集成电路制备中硅衬底精密抛光的研究[硕士学位论文].河北:河北工业大学, 2002,3.
[57] K. Seiichi Abrasive-free polishing for copper damascene interconnection[J]. Electrochem Soc., 2000, 147(10):3907~3711.
[58]刘学璋,王柏春,许向阳,等.不同粒度纳米金刚石抛光微晶玻璃的研究[J].润滑与密封, 2007, 32(9):97~99.
[59] T. Suratwala, R. Steele, M.D. Feit, et al. Effect of rogue particles on the sub-surface damage of fused silica during grinding/polishing[J]. Journal of Non-Crystalline Solids, 2008, 354(18):2023~2037.
[60] G. Fu, A. Chandra. A model for wafer scale variation of material removal rate in CMP based on viscoelastic pad deformation[J]. J. Eletro. Matls., 2002, 31(10):1066~1073.
[61] H. Liang, F. Kaufman, R. Sevilla, et al. Wear phenomena in chemical-mechanical polishing[J]. Wear, 1997, 211(2):271~279.
[62] J. Oung, J. Lee, H. Liang. Modeling of polyurethane as CMP pads[J]. Journal of CMP, 2001(1):323~335.
[63] I. Li, K.M. Forsthoefel, K.A. Richardson, et al. Dynamic mechanical analysis of CMP pad material[C]. MRS Symp, 2000, 613:E.7.3.2~7.3.10.