超深亚微米集成电路制造过程中光学邻近效应模拟的研究
摘要
信息技术的快速发展和集成电路设计的逐步完善，对半导体制造技术提出了更高的要求。集成电路的复杂度越来越高，最小线宽和最小间距变得越来越小。当集成电路的特征尺寸接近光刻机曝光系统的分辨极限时，在硅圆片表面制造出来的电路版图会有明显的畸变，即产生光学邻近效应(OPE—Optical Proximity Effect)，从而严重影响集成电路制造的成品率。为了减少光学邻近效应对集成电路技术发展的影响，工业界提出了光刻分辨率增强技术(RET—Reticle Enhancement Technology)，以使现有的集成电路生产设备在相同的生产条件下能制造出具有更小特征尺寸的集成电路。
象其它的集成电路设计技术一样，光刻分辨率增强技术也需要基于计算机技术的EDA工具的支持。在光刻分辨率增强技术中，需要有光刻模拟过程来支持和指导。光学邻近校正技术(OPC—Optical Proximity Correction)和移相掩模技术(PSM—Phase Shifting Masks)是光刻分辨率增强技术的两种主要技术。不管是采用光学邻近校正技术的掩模图像的预失真或是采用移相掩模技术的掩模相位调整，都要预测在实际光刻条件下掩模在硅片表面的待刻电路层上所成的图像。本文在深入分析了集成电路制造过程的前提下，研究了各个工艺过程的模型，并逐个建立了对应的系统模型，使模拟集成电路的生产过程成为现实。
本文在建立光刻过程的模型中，通过对光刻机的工作原理研究，成功地建立了光刻机照明系统的模型，实现了对曝光过程的模拟，并提出了以双线性系统模型为基础的查表法来加快空间点曝光的模拟；通过对光刻胶特性的研究，实现了高斯模型对光刻胶显影、烘烤过程进行模拟；通过对蚀刻过程的研究，实现了以数据统计为基础的变偏差蚀刻模型(VBM—Variable Bias Model)对蚀刻过程进行模拟。本文还提供了优化方法对各个系统模型进行必要的优化，并用数据统计的方法对优化结果进行统计，以确定最优的模型。
The fast development of information technology and the rapid upgrade of design technologies of VLSI increase the burden of the semiconductor manufacturing. The complexity of IC increases, the feature and spacing dimension in the design become smaller. Therefore, the real shapes created on the wafer will not be consistent with the layout when the feature sizes in the design are shorter than half of the wavelength of lithographic light source; in this case, Optical Proximity Effect (OPE) happens. OPE will result in bad performance circuits or even make the circuits invalid, and so it will significantly reduce the IC manufacture yield. Reticle Enhancement Technology (RET) emerges to retain the convention IC manufacture equipments and enable the stepper to create circuit with smaller features. To intentionally and systematically modify the mask to compensate for optical diffraction limit and process non-idealities is the basic idea of RET.
Like other technologies used in IC design, RET needs the support of computer technology. Basically, RET has two ways to modify the original layouts. One is to change the shapes of the layout on the mask, which is called Optical Proximity Correction (OPC); the other is to assign different phases to different parts of the mask, which is called Phase Shifting Masks (PSM). Both of the two methods need an EDA tool to simulate the image on the wafer before the modification can be carried out. This paper studies the processes of the 1C manufacture, and focuses on how to build the model of each process.
To build the lithographic model, we have studied the theory of how the wafer stepper works, and succeed in realizing the model for the lithographic exposure system. What's more, in this paper, a bilinear model is realized to speed up the sparse point intensity simulation; a Gaussian model is taken to simulate the behavior of the photomask being exposed and baked; an approach based on statistics is realized to build a Variable Bias Model (VBM) to simulate the etching process; an optimization method is presented to optimize the model parameters for the best accuracy.
象其它的集成电路设计技术一样，光刻分辨率增强技术也需要基于计算机技术的EDA工具的支持。在光刻分辨率增强技术中，需要有光刻模拟过程来支持和指导。光学邻近校正技术(OPC—Optical Proximity Correction)和移相掩模技术(PSM—Phase Shifting Masks)是光刻分辨率增强技术的两种主要技术。不管是采用光学邻近校正技术的掩模图像的预失真或是采用移相掩模技术的掩模相位调整，都要预测在实际光刻条件下掩模在硅片表面的待刻电路层上所成的图像。本文在深入分析了集成电路制造过程的前提下，研究了各个工艺过程的模型，并逐个建立了对应的系统模型，使模拟集成电路的生产过程成为现实。
本文在建立光刻过程的模型中，通过对光刻机的工作原理研究，成功地建立了光刻机照明系统的模型，实现了对曝光过程的模拟，并提出了以双线性系统模型为基础的查表法来加快空间点曝光的模拟；通过对光刻胶特性的研究，实现了高斯模型对光刻胶显影、烘烤过程进行模拟；通过对蚀刻过程的研究，实现了以数据统计为基础的变偏差蚀刻模型(VBM—Variable Bias Model)对蚀刻过程进行模拟。本文还提供了优化方法对各个系统模型进行必要的优化，并用数据统计的方法对优化结果进行统计，以确定最优的模型。
The fast development of information technology and the rapid upgrade of design technologies of VLSI increase the burden of the semiconductor manufacturing. The complexity of IC increases, the feature and spacing dimension in the design become smaller. Therefore, the real shapes created on the wafer will not be consistent with the layout when the feature sizes in the design are shorter than half of the wavelength of lithographic light source; in this case, Optical Proximity Effect (OPE) happens. OPE will result in bad performance circuits or even make the circuits invalid, and so it will significantly reduce the IC manufacture yield. Reticle Enhancement Technology (RET) emerges to retain the convention IC manufacture equipments and enable the stepper to create circuit with smaller features. To intentionally and systematically modify the mask to compensate for optical diffraction limit and process non-idealities is the basic idea of RET.
Like other technologies used in IC design, RET needs the support of computer technology. Basically, RET has two ways to modify the original layouts. One is to change the shapes of the layout on the mask, which is called Optical Proximity Correction (OPC); the other is to assign different phases to different parts of the mask, which is called Phase Shifting Masks (PSM). Both of the two methods need an EDA tool to simulate the image on the wafer before the modification can be carried out. This paper studies the processes of the 1C manufacture, and focuses on how to build the model of each process.
To build the lithographic model, we have studied the theory of how the wafer stepper works, and succeed in realizing the model for the lithographic exposure system. What's more, in this paper, a bilinear model is realized to speed up the sparse point intensity simulation; a Gaussian model is taken to simulate the behavior of the photomask being exposed and baked; an approach based on statistics is realized to build a Variable Bias Model (VBM) to simulate the etching process; an optimization method is presented to optimize the model parameters for the best accuracy.
引文
[Anthony98] Anthony Yen, M. Burkhardt, J. R. Ilzhoefer, et. al., "Optical Proximity Correction and its Application to CD Control in High-speed Microprocessors", Microelectronic Engineering 41/42, pp65-70, 1998
[Chen87] Chen P, Chen M, "Proximity effects in submicron optical lithography", SPIE Vol. 772, pp.35-40, 1987
[Chen97] J.F. Chen, Tom Laidig, K.E. Wampler, et al. "Practical Method for Full-Chip Optical Proximity Correction", SPIE, 1997, vol.3051, pp.790-803.
[Christopher00] Christopher Progler and Alfred Wong,"Zernike Coefficients: Are they really enough?", SPIE Vol.4000, pp.40-52,2000.
[Cobb95] N. Cobb and A. Zakhor. "Fast, Low-complexity mask design", In Proceedings of SPIE Symposium on Optical Microlithography Val 2440, Santa Clara, 1995
[Dolainsky97] D. Dolainsky and W. Maurer, "Application of a Simple Resist Model to Fast Optical Proximity Correction", SPIE, 1997, vol.3051, pp.774-780.
[Friedrich99] Christoph Friedrich, Klaus Ergenzinger, Fritz Gans, et al. "Evaluating the Potential of Alternating Phase Shift Masks Using Lithography Simulation", SPIE, 1999, vol.3679, pp.590-599.
[Garofalo95] J. Garofalo, J.Demarco, J.Bailey, J.Xiao, S.Vaidya, "Reduction of ASIC Gate-level Line-end Shortening by Mask Compensation", SPIE Vol.2440, pp. 171-182, 1995
[Graham99] Graham Arthur, Brian Martin, Christine Wallace, et al, "Full-chip optical proximity correction using lithography simulation", SPIE Vol.3546, pp.574-583, 1999
[Hopkins53] H.H. Hopkins, "On the diffraction theory of optical images", Proc. Royal Soc. Series A., Vol.217, No. 1131, pp. 408-432 1953
[Jeffrey00] S. Jeffrey Rosner, Nader Shamma, Frederik Sporon-Fiedler 著，谢中生译，“亚微米光刻中最佳焦深的傅立叶函数分析”，电子工业专业设备，Vol.29, No.1, 2000年3
[John98] John Randall, Alexander Tritchkov, Rik Jonckheere, et al,
"Reduction of Mask Induced CD Errors by Optical Proximity Correction", SPIE Vol.3334, pp. 124-130, 1998
[kahng99] A.B.Kahng and Y.C.Pati, "Sub-Wavelength Optical Lithography: Challenges and Impact on Physical Design", 1999
[Kahng01] A.B.Kahng, Shailesh Vaya, and Alexander Zelikovsky, "New Graph Bipartizations for Double-Exposure, Bright Field Alternating Phase-Shift Mask Layout", in IEEE, 2001, pp. 133-138.
[Kim97] Kim Dang, "Development and characterization of multilevel metal interconnection etch process", SPIE, Vol. 3213, pp.91-100, 1997
[Kuo99] H.J.Kuo, C.H.Lin, S.D.Tzu, et al. "Combination of OPC and AttPSM for Patterning Sub-0.18μm Logic Devices", SPIE, 1999, vol.3679, pp.435-445.
[Lars97] Lars Liebmann, Antoinette Molless, Richard Ferguson et al,"Understanding Across Chip Line Width Variation: The First Step Toward Optical Proximity Correction", SPIE Vol.3051, pp. 124-136, 1997
[Levinson01] H.J. Levinson, "Principles of lithography", SPIE press. 2001
[Linard00] Linard Karklin,B. J.Lin., "Resolution Enhancement Techniques and Mask Manufacturability for Sub-wavelength Lithography", Proceedings of SPIE Vol.4066, pp.40-46,2000
[Liu98] H.Y. Liu, Linard Karklin, Y.T Wang, et al. "The Application of Alternating Phase-shifting Masks to 140nm Gate Patterning(Ⅱ): Mask Design and Manufacturing Tolerances", SPIE, 1998, vol.3334, pp.2-14.
[Ma98] Z.M. Ma and Andrew Andersson, "Preventing sidelobe printing in applying attenuated phase shift reticles", SPIE, 1998, vol.3334, pp.543-552.
[Nick96] Nick Cobb, Avideh Zakhor, and Eugene Miloslavsky, "Mathematical and CAD Frame for Proximity Correction", SPIE Vol.2726 pp.208-211, 1996
[Otto94] O. Otto, J. Garafalo, K. Low, et al, "Automated optical proximity correction-a rules-based approach", SPIE Vol.2197, pp.278-293,
1994
[Roadmap] The National Technology Roadmap for Semiconductors, by Semiconductor Industry Association, 1997 Ed.
[Sheats98] J.R. Sheats, B. W. Smith, "Microlithography Science and Technology", New York, 1998
[Thiele99] Jorg Thiele, Christoph Friedrich, Christoph Dolainsky, et al. "Integration of alternating phase shift mask technology into optical proximity correction", SPIE, 1999, vol.3679, pp. 548-555.
[Toh88] K.K.H. Toh, "Two-dimension Images With Effects of Lens Aberrations in Optical Lithography", Memorandum UCB/ERL M88/30, University of California, Berkeley, May 20, 1988
[Tritchkoy 99] Alexander Tritchkov, John Stirniman, Michael Rieger, "Alternating PSM optimization using model based OPC", SPIE, 1999, vol.3679, pp.556-566.
[Vandenhove95] Vandenhove L., Ronse K., "Challenges for 0.35-0.25-MU-M Optical Lithography", Microelectronic Engineering 27(1-4), pp.357-365, Feb. 1995
[Vinod99] Vinod K. Malhotra, Fang-Cheng Chang, "Verifying the 'Correctness' of your optical proximity correction designs", SPIE Vol.3679, pp. 130-137, 1999
[Wong01] A. Wong. "Resolution enhancement techniques in optical litho graphy", SPIE press. 2001.
[Yong92] Yong Liu, Avideh Zakhor, "Binary and Phase Shifting Mask Design for Optical Lithography", IEEE Transaction on Semiconductor Manufacturing, Vol. 5, No.2, pp. 138-152, 1992
[Yong93] Yong Liu, Avideh Zakhor, "Computer aided phase shift mask design with reduced Complexity ", proceedings of SPIE Symposium on Optical Microlithography, Vol. 1927, pp.477-493, 1993
[Yuri01] Yuri Granik, "Correction for etch proximity: new models and applications", SPIE Vol.4346 pp 98-112, 2001
[冯伯儒00] 冯伯儒，张锦，侯德胜等，“微光刻技术的发展”，微细加工技术，No．1，2000
[李志坚97] 李志坚，“21世纪微电子技术发展展望”，科技导报 Vol．3，1997
[石瑞英00] 石瑞英，郭永康，曾阳素等，“光学邻近效应的产生机理分析”，激光杂志，Vol．21，No．4，2000
[石瑞英01] 石瑞英，郭永康，“光学邻近校正改善亚微米光刻图形质量”，半导体技术，第26卷第3期，2001，3
[沈绪榜95] 沈绪榜，杜敏，“VLSI设计导论”，高等教育出版社，1995。
[苏雪莲01) 苏雪莲，“新世纪光刻技术及光刻设备的发展趋势”，微电子技术，Vol．29，No．2，2001年4月
[谢常青00] 谢常青，“深亚微米光学光刻设备制造技术”，电子工业专用设备，Vol．29，No．2，2000年6月
[Chen87] Chen P, Chen M, "Proximity effects in submicron optical lithography", SPIE Vol. 772, pp.35-40, 1987
[Chen97] J.F. Chen, Tom Laidig, K.E. Wampler, et al. "Practical Method for Full-Chip Optical Proximity Correction", SPIE, 1997, vol.3051, pp.790-803.
[Christopher00] Christopher Progler and Alfred Wong,"Zernike Coefficients: Are they really enough?", SPIE Vol.4000, pp.40-52,2000.
[Cobb95] N. Cobb and A. Zakhor. "Fast, Low-complexity mask design", In Proceedings of SPIE Symposium on Optical Microlithography Val 2440, Santa Clara, 1995
[Dolainsky97] D. Dolainsky and W. Maurer, "Application of a Simple Resist Model to Fast Optical Proximity Correction", SPIE, 1997, vol.3051, pp.774-780.
[Friedrich99] Christoph Friedrich, Klaus Ergenzinger, Fritz Gans, et al. "Evaluating the Potential of Alternating Phase Shift Masks Using Lithography Simulation", SPIE, 1999, vol.3679, pp.590-599.
[Garofalo95] J. Garofalo, J.Demarco, J.Bailey, J.Xiao, S.Vaidya, "Reduction of ASIC Gate-level Line-end Shortening by Mask Compensation", SPIE Vol.2440, pp. 171-182, 1995
[Graham99] Graham Arthur, Brian Martin, Christine Wallace, et al, "Full-chip optical proximity correction using lithography simulation", SPIE Vol.3546, pp.574-583, 1999
[Hopkins53] H.H. Hopkins, "On the diffraction theory of optical images", Proc. Royal Soc. Series A., Vol.217, No. 1131, pp. 408-432 1953
[Jeffrey00] S. Jeffrey Rosner, Nader Shamma, Frederik Sporon-Fiedler 著，谢中生译，“亚微米光刻中最佳焦深的傅立叶函数分析”，电子工业专业设备，Vol.29, No.1, 2000年3
[John98] John Randall, Alexander Tritchkov, Rik Jonckheere, et al,
"Reduction of Mask Induced CD Errors by Optical Proximity Correction", SPIE Vol.3334, pp. 124-130, 1998
[kahng99] A.B.Kahng and Y.C.Pati, "Sub-Wavelength Optical Lithography: Challenges and Impact on Physical Design", 1999
[Kahng01] A.B.Kahng, Shailesh Vaya, and Alexander Zelikovsky, "New Graph Bipartizations for Double-Exposure, Bright Field Alternating Phase-Shift Mask Layout", in IEEE, 2001, pp. 133-138.
[Kim97] Kim Dang, "Development and characterization of multilevel metal interconnection etch process", SPIE, Vol. 3213, pp.91-100, 1997
[Kuo99] H.J.Kuo, C.H.Lin, S.D.Tzu, et al. "Combination of OPC and AttPSM for Patterning Sub-0.18μm Logic Devices", SPIE, 1999, vol.3679, pp.435-445.
[Lars97] Lars Liebmann, Antoinette Molless, Richard Ferguson et al,"Understanding Across Chip Line Width Variation: The First Step Toward Optical Proximity Correction", SPIE Vol.3051, pp. 124-136, 1997
[Levinson01] H.J. Levinson, "Principles of lithography", SPIE press. 2001
[Linard00] Linard Karklin,B. J.Lin., "Resolution Enhancement Techniques and Mask Manufacturability for Sub-wavelength Lithography", Proceedings of SPIE Vol.4066, pp.40-46,2000
[Liu98] H.Y. Liu, Linard Karklin, Y.T Wang, et al. "The Application of Alternating Phase-shifting Masks to 140nm Gate Patterning(Ⅱ): Mask Design and Manufacturing Tolerances", SPIE, 1998, vol.3334, pp.2-14.
[Ma98] Z.M. Ma and Andrew Andersson, "Preventing sidelobe printing in applying attenuated phase shift reticles", SPIE, 1998, vol.3334, pp.543-552.
[Nick96] Nick Cobb, Avideh Zakhor, and Eugene Miloslavsky, "Mathematical and CAD Frame for Proximity Correction", SPIE Vol.2726 pp.208-211, 1996
[Otto94] O. Otto, J. Garafalo, K. Low, et al, "Automated optical proximity correction-a rules-based approach", SPIE Vol.2197, pp.278-293,
1994
[Roadmap] The National Technology Roadmap for Semiconductors, by Semiconductor Industry Association, 1997 Ed.
[Sheats98] J.R. Sheats, B. W. Smith, "Microlithography Science and Technology", New York, 1998
[Thiele99] Jorg Thiele, Christoph Friedrich, Christoph Dolainsky, et al. "Integration of alternating phase shift mask technology into optical proximity correction", SPIE, 1999, vol.3679, pp. 548-555.
[Toh88] K.K.H. Toh, "Two-dimension Images With Effects of Lens Aberrations in Optical Lithography", Memorandum UCB/ERL M88/30, University of California, Berkeley, May 20, 1988
[Tritchkoy 99] Alexander Tritchkov, John Stirniman, Michael Rieger, "Alternating PSM optimization using model based OPC", SPIE, 1999, vol.3679, pp.556-566.
[Vandenhove95] Vandenhove L., Ronse K., "Challenges for 0.35-0.25-MU-M Optical Lithography", Microelectronic Engineering 27(1-4), pp.357-365, Feb. 1995
[Vinod99] Vinod K. Malhotra, Fang-Cheng Chang, "Verifying the 'Correctness' of your optical proximity correction designs", SPIE Vol.3679, pp. 130-137, 1999
[Wong01] A. Wong. "Resolution enhancement techniques in optical litho graphy", SPIE press. 2001.
[Yong92] Yong Liu, Avideh Zakhor, "Binary and Phase Shifting Mask Design for Optical Lithography", IEEE Transaction on Semiconductor Manufacturing, Vol. 5, No.2, pp. 138-152, 1992
[Yong93] Yong Liu, Avideh Zakhor, "Computer aided phase shift mask design with reduced Complexity ", proceedings of SPIE Symposium on Optical Microlithography, Vol. 1927, pp.477-493, 1993
[Yuri01] Yuri Granik, "Correction for etch proximity: new models and applications", SPIE Vol.4346 pp 98-112, 2001
[冯伯儒00] 冯伯儒，张锦，侯德胜等，“微光刻技术的发展”，微细加工技术，No．1，2000
[李志坚97] 李志坚，“21世纪微电子技术发展展望”，科技导报 Vol．3，1997
[石瑞英00] 石瑞英，郭永康，曾阳素等，“光学邻近效应的产生机理分析”，激光杂志，Vol．21，No．4，2000
[石瑞英01] 石瑞英，郭永康，“光学邻近校正改善亚微米光刻图形质量”，半导体技术，第26卷第3期，2001，3
[沈绪榜95] 沈绪榜，杜敏，“VLSI设计导论”，高等教育出版社，1995。
[苏雪莲01) 苏雪莲，“新世纪光刻技术及光刻设备的发展趋势”，微电子技术，Vol．29，No．2，2001年4月
[谢常青00] 谢常青，“深亚微米光学光刻设备制造技术”，电子工业专用设备，Vol．29，No．2，2000年6月
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