ULSI铜互连层CMP抛光液研究
摘要
随着集成电路(IC)特征线宽微细化进程的加快，光刻焦深变得越来越短，对IC芯片表面平整度的要求也越来越苛刻，加之硅片直径的增大和金属布线层数的不断增加，给化学机械平坦化(chemical mechanical planarization，CMP)技术带来了前所未有的挑战。虽然CMP技术被认为是目前可以兼顾IC芯片全局和局部平整度要求的、最实用的超大规模集成电路(ULSI)铜互连层平坦化方法，但由于铜CMP抛光机理极为复杂，仍然存在工艺稳定性差、成品率和生产率较低等问题。在CMP过程中，铜CMP抛光液对被加工表面具有化学腐蚀和机械研磨的双重作用，对抛光效果有着重要影响，目前仍存在诸如金属离子污染、分散性差、碱性环境下材料去除率低等问题。深入研究铜CMP材料去除机理以及研究和开发更高性能抛光液是解决上述问题的有效途径，也是当前CMP技术领域的研究热点。
本文以ULSI铜互连层CMP抛光液配方为研究方向，在介绍、分析抛光液的材料去除原理和特点以及总结已有研究成果的基础上，将研究定位于碱性铜抛光液，以提高抛光液的材料去除率、降低抛光液中金属离子含量和提高抛光质量为目标，进行了抛光液配方选择和优化方面的研究，找到了较好的抛光液成分和配方，研制出了性能良好的碱性铜抛光液。
本文的研究思路为：首先通过对铜CMP机理的研究，找到影响抛光质量的主要因素，并结合当前铜抛光液存在的一些主要问题制定抛光液成分选择和配方优化的试验方案。然后，讨论了抛光液各成分的作用原理，以UNIPOL1502型研磨抛光机和CETR公司CP-4型抛光机为试验平台，进行了抛光液成分选择的单因素试验，通过试验选出了较适合ULSI铜互连层抛光的纳米磨料、氧化剂、有机碱、表面活性剂和分散剂等主要成分。接着，以单因素试验选出的主要成分为基础，又进行了复配次序优化、工艺参数和组分优化等试验，得到了抛光效率较高，性能良好的碱性铜抛光液。
研究成果为提高碱性铜抛光液的抛光质量、材料去除率以及改善抛光液性能，提供了比较系统的研究方法和丰富的试验结论，对进一步完善ULSI铜互连层平坦化技术具有重要指导意义。
Along with the feature size of IC becoming smaller and smaller, the depth of focus of photoetching technique is becoming shorter and shorter. The requirements to surface flatness also turn to more rigorous than before. The increasing of silicon wafer diameter and layers of multi-level metal interconnects bring CMP technology an unprecedented challenge. Although the CMP technology is considered as the most applied and irreplaceable method for realizing local and global planarization during the manufacturing process of IC, but because the complexity of copper CMP mechanism, there are still some problems such as worse technique stability, low rate of finished products and productivity. In the process of CMP, the copper CMP slurry make a dual function of chemical erosion and mechanical lapping, have an important influence to the surface quality. Now, copper CMP slurry still has the problems of metal ion contamination, low material removal rate in alkalescent environment and so on. Studying the material removal mechanism thoroughly of copper CMP and developing high performance CMP slurry, as two doable approaches to resolve problems that mentioned above, has become the researching focuses in the CMP technology field recently.
The subject of this paper is the study of slurry prescription suitable for copper interconnection layer in ULSI manufacturing. For reducing metal ions content, improving material removal rate, the selection of slurry prescription and optimization is studied through many theories and experiments. Meanwhile, the material removal mechanism has also been discussed. At last, the ingredients and prescription of slurry is found, and the slurry is made with well properties.
The researching route of this paper is: Firstly, the CMP mechanism has been studied in this paper. The factors that influence the polishing quality mostly have been found. At the same time after considering the main problems of copper slurry at present, the projects of selecting ingredients and optimizing prescription have been established. Secondly, the functions of main ingredients of slurry have been analyzed. The single factor experiments of every ingredients of slurry have been carried out on the UNIPOL1502 lapping polishing machine and CP-4 polishing machine. Through the experiment, the main ingredients of slurry, such as abrasive, organic alkali, oxidant etc, have been selected that suitable for the copper polishing. Lastly, on the basis of research before, the optimization experiments of parameters and ingredients have been carried out, finally got a sort of high efficiency and high performance alkalescent copper slurry.
The study of this paper provides a kind of systemic researching methods and a group of useful experimental conclusions for improving the polishing quality of alkalescent copper slurry, increasing the material removal rate and how to optimize the slurry description. It has significant meaning for developing the metal interconnection layer planarization technology for Ultra Large Scale Integrate Circuit.
本文以ULSI铜互连层CMP抛光液配方为研究方向，在介绍、分析抛光液的材料去除原理和特点以及总结已有研究成果的基础上，将研究定位于碱性铜抛光液，以提高抛光液的材料去除率、降低抛光液中金属离子含量和提高抛光质量为目标，进行了抛光液配方选择和优化方面的研究，找到了较好的抛光液成分和配方，研制出了性能良好的碱性铜抛光液。
本文的研究思路为：首先通过对铜CMP机理的研究，找到影响抛光质量的主要因素，并结合当前铜抛光液存在的一些主要问题制定抛光液成分选择和配方优化的试验方案。然后，讨论了抛光液各成分的作用原理，以UNIPOL1502型研磨抛光机和CETR公司CP-4型抛光机为试验平台，进行了抛光液成分选择的单因素试验，通过试验选出了较适合ULSI铜互连层抛光的纳米磨料、氧化剂、有机碱、表面活性剂和分散剂等主要成分。接着，以单因素试验选出的主要成分为基础，又进行了复配次序优化、工艺参数和组分优化等试验，得到了抛光效率较高，性能良好的碱性铜抛光液。
研究成果为提高碱性铜抛光液的抛光质量、材料去除率以及改善抛光液性能，提供了比较系统的研究方法和丰富的试验结论，对进一步完善ULSI铜互连层平坦化技术具有重要指导意义。
Along with the feature size of IC becoming smaller and smaller, the depth of focus of photoetching technique is becoming shorter and shorter. The requirements to surface flatness also turn to more rigorous than before. The increasing of silicon wafer diameter and layers of multi-level metal interconnects bring CMP technology an unprecedented challenge. Although the CMP technology is considered as the most applied and irreplaceable method for realizing local and global planarization during the manufacturing process of IC, but because the complexity of copper CMP mechanism, there are still some problems such as worse technique stability, low rate of finished products and productivity. In the process of CMP, the copper CMP slurry make a dual function of chemical erosion and mechanical lapping, have an important influence to the surface quality. Now, copper CMP slurry still has the problems of metal ion contamination, low material removal rate in alkalescent environment and so on. Studying the material removal mechanism thoroughly of copper CMP and developing high performance CMP slurry, as two doable approaches to resolve problems that mentioned above, has become the researching focuses in the CMP technology field recently.
The subject of this paper is the study of slurry prescription suitable for copper interconnection layer in ULSI manufacturing. For reducing metal ions content, improving material removal rate, the selection of slurry prescription and optimization is studied through many theories and experiments. Meanwhile, the material removal mechanism has also been discussed. At last, the ingredients and prescription of slurry is found, and the slurry is made with well properties.
The researching route of this paper is: Firstly, the CMP mechanism has been studied in this paper. The factors that influence the polishing quality mostly have been found. At the same time after considering the main problems of copper slurry at present, the projects of selecting ingredients and optimizing prescription have been established. Secondly, the functions of main ingredients of slurry have been analyzed. The single factor experiments of every ingredients of slurry have been carried out on the UNIPOL1502 lapping polishing machine and CP-4 polishing machine. Through the experiment, the main ingredients of slurry, such as abrasive, organic alkali, oxidant etc, have been selected that suitable for the copper polishing. Lastly, on the basis of research before, the optimization experiments of parameters and ingredients have been carried out, finally got a sort of high efficiency and high performance alkalescent copper slurry.
The study of this paper provides a kind of systemic researching methods and a group of useful experimental conclusions for improving the polishing quality of alkalescent copper slurry, increasing the material removal rate and how to optimize the slurry description. It has significant meaning for developing the metal interconnection layer planarization technology for Ultra Large Scale Integrate Circuit.
引文
[1] Imai. M, Mayusumi. M, moue. K, et al. Issues for the larger diameter epitaxial wafer. Microelectronic Engineering. 2001,56(1-2):109-115.
[2] Song Dengyuan, Zong Xiaoping, Sun Rongxia et al. Copper Connections for IC and Studies on Related Problems. Semiconductor Technology. 2001,26(2):29-32.
[3] Sami Franssila. Introduction to microfabrication. Finland: John Wiley&Sons, Inc., 2004.
[4] John Schuler著，立文译．CMP技术与市场．电子工业专用设备．2000，29(1)：1-5．
[5] 翁寿松．CMP的最新动态．电子工业专用设备．2005，120：7-9．
[6] 李秀娟，金洙吉，苏建修等．铜化学机械抛光中的平坦化问题研究．半导体技术．2004，(29)：30-34．
[7] 刘玉岭，檀柏梅．超大规模集成电路衬底材料性能及加工测试技术工程．北京：冶金工业出版社，2002．
[8] 袁巨龙，袁哲俊．功能陶瓷的超精密加工技术．哈尔滨：哈尔滨工业大学出版社，2000．
[9] 江瑞生．集成电路多层结构中的化学机械抛光技术．半导体技术．1998，23(1)：6-7．
[10] 赵永武，刘家浚．半导体芯片化学机械抛光过程中材料去除机理研究进展．摩擦学学报．2004，24(3)：283-287．
[11] 李秀娟，金洙吉，康仁科等．ULSI制造中铜化学机械抛光的腐蚀磨损机理分析．润滑与密封．2005，(7)：77-80．
[12] 郭东明，康仁科，金洙吉．大尺寸硅片的高效超精密加工技术．世界制造技术与装备市场．2003，(1)：35-40．
[13] Michael Quirk，Julian Serda．半导体制造技术．北京：电子工业出版社，2004．
[14] 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技术的未来发展．机械工程学报．2003，39(10)：100-105．
[15] 刘玉岭，植柏梅，张楷亮编著．超大规模集成电路衬底材料性能及加工测试技术工程．冶金工业出版社，2002．
[16] P. Wolters. http://www.peter-wolters.com/cmp/cmpmultilevel.htm, 2003.
[17] Z. Stavreva, D. Zeidler, M. Plotner et al. Chemical mechanical polishing of copper for multilevel Metallization. Applied Surface Science. 1995, (91):192-196.
[18] 张楷亮，宋志棠，封松林．化学机械抛光的研究与展望．微电子学．2005，(35)：226-230．
[19] ThakurtaDG, BorstCL, SchwendemanDW et al. Compressibility and Slurry Delivery in Chemical-mechanical Planarization. Modeling and Experiments. 2000, (366):181-190.
[20] 刘若冰，铜工艺成功跨越IC技术的鸿沟．电子产品世界．2002，(7)：70-71．
[21] J.R. Lloyd, J. Clements. Copper Metallization Reliability. Microelectronics Reliability. 1999, (39):1595-1602.
[22] 翁寿松．铜布线及其设备．电子工业专用设备．1999，(3)：13．
[23] 陈智涛．集成电路片内铜互连技术的发展．微电子学．2001，(24)：4．
[24] 翁寿松．90nm工艺及其相关工艺．微纳电子技术．2003，40(4)：32．
[25] 刘洪图，吴自勤．超大规模集成电路的一些材料物理问题—Cu互连和金属化．物理．2001，30(12)：757-761．
[26] 黄洁．半导体金属互连集成技术的进展与趋势．金属热处理．2004，(8)：26-31．
[27] M.A. Korhonen, W.R. Lafortaine. Stress-Induced Nucleation of Void in Narrow Aluminum-based Metallization on Silicon Substrates. J. Appl. Phys. 1991,70(11):6774-6781.
[28] Hidekazu Okabayashi. An Analytical Open-Failure Lifetime Model for Stress-Induced Voiding in Aluminum Lines. IEEL transactions on electron devices. 1993,40(4):782-788.
[29] 张厥宗编著．硅单晶抛光片的加工技术．北京：化学工业出版社，2005．
[30] 轩久霞．ULSI中的铜互连线RC延迟．电子产品可靠性与环境试验．2003，(3)：33-37．
[31] 宋登元，宗晓萍．集成电路铜互连线及相关问题的研究．半导体技术．2001，(2)：29-32．
[32] 王灵婕，林吉申．铜互连技术．鹭江职业大学学报．2005，(3)：60-62．
[33] 李秀娟，金洙吉，康仁科等．抛光液中缓蚀剂对铜硅片的影响．半导体学报．2005，26(11)：111-115．
[34] 陈苏，张楷亮，宋志棠．多层互连工艺中铜布线化学机械抛光研究进展．半导体技术．2005，(30)：21-24．
[35] 王新，刘玉岭，檀柏梅．用于铜的化学机械抛光液的研究．固体电子学研究与进展．2002，(22)：318-320
[36] 何捍卫，胡岳华，黄可龙．铜在氨水介质铁氰化钾CMP抛液中抛光速率及其影响因素的研究．电化学．2002，(8)：202-206．
[37] 王新，刘玉岭，康志龙．铜CMP中SiO_2抛光液的凝胶及其消除实验．半导体技术．2003，(28)：63-64．
[38] F W Preston. The theory and design of plate glass polishing machines. J. Soc. Glass Tech. 1927, (11):214.
[39] F B Kaufman, D B Thompson, R E Broadie et al. J. Electrochem. Soc. 1991, (139): 3460.
[40] 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．半导体技术．2003，28(10)：27-32．
[41] 苏建修，郭东明，康仁科等．硅片化学机械抛光时硅片运动形式对片内非均匀性的影响分析．中国机械工程．2005，16(9)：815-818．
[42] 邢哲，刘玉岭，檀柏梅等．ULSI铜多层布线中钽阻挡层CMP抛光液的研究与优化．半导体学报．2004，(25)：1726-1728．
[43] 张楷亮，宋志棠，封松林．化学机械抛光的研究与展望．微电子学．2005，(35)：226-230．
[44] 张朝辉，雒建斌，雷红．化学机械抛光中的纳米级薄膜流动．中国机械工程．2005，(16)：1282-1285．
[45] Z Stavreva, D Zeidler, M Plotner et al. Influence of Process Parameter on Chemical Mechanical Polishing of Copper. Microelectronic Engineering. 1997, (37):143-149.
[46] 李庆忠，金洙吉，张然等．分散剂对铜CMP材料去除率和表面粗糙度影响的实验研究．润滑与密封．2006，32(3)：70-72．
[47] 蒋建忠，赵永武．CMP过程芯片表面氧化膜生成速度影响因素的分析．现代制造工程．2006，(10)：51-55．
[48] Q.Z. Li, Z.J. Jin, R. K. Kang et al. Experimental Study on Influences of Organic Alkali on Material Removal Rate of Cu CMP. ICSFT. 2006:317-322.
[49] 童志义．化学机械抛光技术现状及发展趋势．电子工业用设备．2004，(6)：1-6．
[50] D Zeidler, Z Stavreva, M Plotner et al. The interaction Between Different Barrier Metals and the Copper Surface during the Chemical Mechanical Polishing. 1997, (37/38):273-243.
[51] 蒋庆哲．表面活性剂科学与应用．北京：中国石化出版社，2006．
[52] Zhang Kai liang, Liu Yu ling, Wang Fang. Study on Controlling the Adsorption State of Particle on the Polished Silicon Wafer. IEEE 2001 6th International Conference on Solid-State and Integrated Circuit Technology Proceedings, 2001:464-467.
[53] Liu Yu ling, Zhang Kai liang, Wang Fang. Study on the Cleaning of silicon after CMP in ULSI. Microelectronic Engineering. 2003,66(1-4):433-437.
[54] Lin Bin-Tiao, Chen C.S., Yeh W.K. Surfactant behavior and study in slurry. IEEE/SEMI advanced semiconductor manufacturing conference, 2002:362-367.
[55] 刘文卿．实验设计．北京：清华大学出版社，2005．
[2] Song Dengyuan, Zong Xiaoping, Sun Rongxia et al. Copper Connections for IC and Studies on Related Problems. Semiconductor Technology. 2001,26(2):29-32.
[3] Sami Franssila. Introduction to microfabrication. Finland: John Wiley&Sons, Inc., 2004.
[4] John Schuler著，立文译．CMP技术与市场．电子工业专用设备．2000，29(1)：1-5．
[5] 翁寿松．CMP的最新动态．电子工业专用设备．2005，120：7-9．
[6] 李秀娟，金洙吉，苏建修等．铜化学机械抛光中的平坦化问题研究．半导体技术．2004，(29)：30-34．
[7] 刘玉岭，檀柏梅．超大规模集成电路衬底材料性能及加工测试技术工程．北京：冶金工业出版社，2002．
[8] 袁巨龙，袁哲俊．功能陶瓷的超精密加工技术．哈尔滨：哈尔滨工业大学出版社，2000．
[9] 江瑞生．集成电路多层结构中的化学机械抛光技术．半导体技术．1998，23(1)：6-7．
[10] 赵永武，刘家浚．半导体芯片化学机械抛光过程中材料去除机理研究进展．摩擦学学报．2004，24(3)：283-287．
[11] 李秀娟，金洙吉，康仁科等．ULSI制造中铜化学机械抛光的腐蚀磨损机理分析．润滑与密封．2005，(7)：77-80．
[12] 郭东明，康仁科，金洙吉．大尺寸硅片的高效超精密加工技术．世界制造技术与装备市场．2003，(1)：35-40．
[13] Michael Quirk，Julian Serda．半导体制造技术．北京：电子工业出版社，2004．
[14] 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技术的未来发展．机械工程学报．2003，39(10)：100-105．
[15] 刘玉岭，植柏梅，张楷亮编著．超大规模集成电路衬底材料性能及加工测试技术工程．冶金工业出版社，2002．
[16] P. Wolters. http://www.peter-wolters.com/cmp/cmpmultilevel.htm, 2003.
[17] Z. Stavreva, D. Zeidler, M. Plotner et al. Chemical mechanical polishing of copper for multilevel Metallization. Applied Surface Science. 1995, (91):192-196.
[18] 张楷亮，宋志棠，封松林．化学机械抛光的研究与展望．微电子学．2005，(35)：226-230．
[19] ThakurtaDG, BorstCL, SchwendemanDW et al. Compressibility and Slurry Delivery in Chemical-mechanical Planarization. Modeling and Experiments. 2000, (366):181-190.
[20] 刘若冰，铜工艺成功跨越IC技术的鸿沟．电子产品世界．2002，(7)：70-71．
[21] J.R. Lloyd, J. Clements. Copper Metallization Reliability. Microelectronics Reliability. 1999, (39):1595-1602.
[22] 翁寿松．铜布线及其设备．电子工业专用设备．1999，(3)：13．
[23] 陈智涛．集成电路片内铜互连技术的发展．微电子学．2001，(24)：4．
[24] 翁寿松．90nm工艺及其相关工艺．微纳电子技术．2003，40(4)：32．
[25] 刘洪图，吴自勤．超大规模集成电路的一些材料物理问题—Cu互连和金属化．物理．2001，30(12)：757-761．
[26] 黄洁．半导体金属互连集成技术的进展与趋势．金属热处理．2004，(8)：26-31．
[27] M.A. Korhonen, W.R. Lafortaine. Stress-Induced Nucleation of Void in Narrow Aluminum-based Metallization on Silicon Substrates. J. Appl. Phys. 1991,70(11):6774-6781.
[28] Hidekazu Okabayashi. An Analytical Open-Failure Lifetime Model for Stress-Induced Voiding in Aluminum Lines. IEEL transactions on electron devices. 1993,40(4):782-788.
[29] 张厥宗编著．硅单晶抛光片的加工技术．北京：化学工业出版社，2005．
[30] 轩久霞．ULSI中的铜互连线RC延迟．电子产品可靠性与环境试验．2003，(3)：33-37．
[31] 宋登元，宗晓萍．集成电路铜互连线及相关问题的研究．半导体技术．2001，(2)：29-32．
[32] 王灵婕，林吉申．铜互连技术．鹭江职业大学学报．2005，(3)：60-62．
[33] 李秀娟，金洙吉，康仁科等．抛光液中缓蚀剂对铜硅片的影响．半导体学报．2005，26(11)：111-115．
[34] 陈苏，张楷亮，宋志棠．多层互连工艺中铜布线化学机械抛光研究进展．半导体技术．2005，(30)：21-24．
[35] 王新，刘玉岭，檀柏梅．用于铜的化学机械抛光液的研究．固体电子学研究与进展．2002，(22)：318-320
[36] 何捍卫，胡岳华，黄可龙．铜在氨水介质铁氰化钾CMP抛液中抛光速率及其影响因素的研究．电化学．2002，(8)：202-206．
[37] 王新，刘玉岭，康志龙．铜CMP中SiO_2抛光液的凝胶及其消除实验．半导体技术．2003，(28)：63-64．
[38] F W Preston. The theory and design of plate glass polishing machines. J. Soc. Glass Tech. 1927, (11):214.
[39] F B Kaufman, D B Thompson, R E Broadie et al. J. Electrochem. Soc. 1991, (139): 3460.
[40] 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．半导体技术．2003，28(10)：27-32．
[41] 苏建修，郭东明，康仁科等．硅片化学机械抛光时硅片运动形式对片内非均匀性的影响分析．中国机械工程．2005，16(9)：815-818．
[42] 邢哲，刘玉岭，檀柏梅等．ULSI铜多层布线中钽阻挡层CMP抛光液的研究与优化．半导体学报．2004，(25)：1726-1728．
[43] 张楷亮，宋志棠，封松林．化学机械抛光的研究与展望．微电子学．2005，(35)：226-230．
[44] 张朝辉，雒建斌，雷红．化学机械抛光中的纳米级薄膜流动．中国机械工程．2005，(16)：1282-1285．
[45] Z Stavreva, D Zeidler, M Plotner et al. Influence of Process Parameter on Chemical Mechanical Polishing of Copper. Microelectronic Engineering. 1997, (37):143-149.
[46] 李庆忠，金洙吉，张然等．分散剂对铜CMP材料去除率和表面粗糙度影响的实验研究．润滑与密封．2006，32(3)：70-72．
[47] 蒋建忠，赵永武．CMP过程芯片表面氧化膜生成速度影响因素的分析．现代制造工程．2006，(10)：51-55．
[48] Q.Z. Li, Z.J. Jin, R. K. Kang et al. Experimental Study on Influences of Organic Alkali on Material Removal Rate of Cu CMP. ICSFT. 2006:317-322.
[49] 童志义．化学机械抛光技术现状及发展趋势．电子工业用设备．2004，(6)：1-6．
[50] D Zeidler, Z Stavreva, M Plotner et al. The interaction Between Different Barrier Metals and the Copper Surface during the Chemical Mechanical Polishing. 1997, (37/38):273-243.
[51] 蒋庆哲．表面活性剂科学与应用．北京：中国石化出版社，2006．
[52] Zhang Kai liang, Liu Yu ling, Wang Fang. Study on Controlling the Adsorption State of Particle on the Polished Silicon Wafer. IEEE 2001 6th International Conference on Solid-State and Integrated Circuit Technology Proceedings, 2001:464-467.
[53] Liu Yu ling, Zhang Kai liang, Wang Fang. Study on the Cleaning of silicon after CMP in ULSI. Microelectronic Engineering. 2003,66(1-4):433-437.
[54] Lin Bin-Tiao, Chen C.S., Yeh W.K. Surfactant behavior and study in slurry. IEEE/SEMI advanced semiconductor manufacturing conference, 2002:362-367.
[55] 刘文卿．实验设计．北京：清华大学出版社，2005．