SISO run-to-run feedback controller using triple EWMA smoothing for semiconductor manufacturing processes

During the past decade, a variety of 'run-to-run' (R2R) control schemes have been proposed and extensively investigated under various assumed models of process dynamics and disturbances whilst applied to the setpoints (recipe) adjustment between batches for the production of semiconductor manufacturing. The R2R control mechanism of this kind represents an interdisciplinary methodology combining response surface modelling, engineering process control (EPC) and statistical process control (SPC), of which the main objective is to fine-tune the recipe so as to maintain the process output of each run as close to the nominal target as possible. In this paper, the single-input single-output (SISO) case is addressed. To overcome the shortcomings in published R2R controllers, an EWMA feedback controller through a strategy of triple smoothing is proposed (in line with the construction of EWMA statistics) which, in the standard R2R practice, compensates process shifts, a deterministic process drift, disturbance of coloured noises, as well as positive autocorrelation (up to the autoregressive order of two) present in the observed response. It is shown via an experimental study that the triple EWMA filter can provide better control performance for R2R applications as compared with those of the control actions of double EWMA and self-tuning (ST). At last, a relevant application to chemical mechanical planarization (CMP) in semiconductor manufacturing, a critical step in chip fabrication, is used to illustrate the proposed controller.

[1]  Armann Ingolfsson,et al.  Stability and Sensitivity of an EWMA Controller , 1993 .

[2]  Enrique Del Castillo,et al.  Some Properties of EWMA Feedback Quality Adjustment Schemes for Drifting Disturbances , 2001 .

[3]  S. Adivikolanu,et al.  Extensions and performance/robustness tradeoffs of the EWMA run-to-run controller by using the internal model control structure , 2000 .

[4]  Duane S. Boning,et al.  Run by run advanced process control of metal sputter deposition , 1998, ICMTS 1998.

[5]  Duane S. Boning,et al.  Run by run control of chemical-mechanical polishing , 1995, Seventeenth IEEE/CPMT International Electronics Manufacturing Technology Symposium. 'Manufacturing Technologies - Present and Future'.

[6]  Enrique Del Castillo,et al.  A multivariate self-tuning controller for run-to-run process control under shift and trend disturbances , 1996 .

[7]  G. E. Taylor,et al.  Computer Controlled Systems: Theory and Design , 1985 .

[8]  John F. MacGregor,et al.  A different view of the funnel experiment , 1990 .

[9]  G. Jenkins,et al.  Some Statistical Aspects of Adaptive Optimization and Control , 1962 .

[10]  B. Mark.  On Self Tuning Regulators , 1972 .

[11]  S. W. Butler,et al.  Supervisory run-to-run control of polysilicon gate etch using in situ ellipsometry , 1994 .

[12]  Lennart Ljung,et al.  System Identification: Theory for the User , 1987 .

[13]  Thomas P. Ryan,et al.  Statistical Control by Monitoring and Feedback Adjustment , 1998 .

[14]  Karl Johan Åström,et al.  Computer-Controlled Systems: Theory and Design , 1984 .

[15]  N. Patel,et al.  Adaptive optimization of run-to-run controllers: the EWMA example , 2000 .

[16]  S. Saxena,et al.  A monitor wafer based controller for semiconductor processes , 1994 .

[17]  Enrique Del Castillo,et al.  Long run and transient analysis of a double EWMA feedback controller , 1999 .

[18]  Arnon M. Hurwitz,et al.  Run-to-Run Process Control: Literature Review and Extensions , 1997 .

[19]  Björn Wittenmark,et al.  A Self-tuning Regulator , 1973 .

[20]  Armann Ingolfsson,et al.  Run by run process control: combining SPC and feedback control , 1995 .

[21]  George E. P. Box,et al.  Discrete proportional-integral control with constrained adjustment , 1995 .

[22]  John F. MacGregor,et al.  Self-Tuning and Adaptive Controllers: An Application to Catalytic Reactor Control , 1980 .

[23]  Björn Wittenmark,et al.  On Self Tuning Regulators , 1973 .

[24]  Ruey-Shan Guo,et al.  Age-based double EWMA controller and its application to CMP processes , 2001 .

[25]  Jinn-Yi Yeh,et al.  An adaptive run-to-run optimizing controller for linear and nonlinear semiconductor processes , 1998, ICMTS 1998.

[26]  K. Åström.  Introduction to Stochastic Control Theory , 1970 .

[27]  George E. P. Box,et al.  Statistical Control: By Monitoring and Feedback Adjustment , 1997 .

[28]  J. Si,et al.  Monitoring and control of semiconductor manufacturing processes , 1998 .

[29]  Armann Ingolfsson,et al.  Modeling and control of an epitaxial silicon deposition process with step disturbances , 1991, [1991 Proceedings] IEEE/SEMI Advanced Semiconductor Manufacturing Conference and Workshop.

[30]  B. Pasik-Duncan,et al.  Adaptive Control , 1996, IEEE Control Systems.

[31]  Sirish L. Shah,et al.  Recursive least squares based estimation schemes for self‐tuning control , 1991 .