Terminal iterative learning control with an application to RTPCVD thickness control

A special type of iterative learning control (ILC) problem is considered. Due to the insufficient measurement capability in many real control problems such as Rapid Thermal Processing (RTP), it may happen that only the terminal output tracking error instead of the whole output trajectory tracking error is available. In the RTP chemical vapor deposition (CVD) of wafer fab. industry, the ultimate control objective is to control the deposition thickness (DT) at the end of the RTP cycle. The control profile for the next operation cycle has to be updated using the terminal DT tracking error alone. A revised ILC method is proposed to address this terminal output tracking problem. By parameterizing the control profile with a piecewise continuous functional basis, the parameters are updated by a high-order updating scheme. A convergence condition is obtained for a class of uncertain discrete-time time-varying linear systems including the RTPCVD system as the subset. Simulation results for an RTPCVD thickness control problem are presented to demonstrate the effectiveness of the proposed iterative learning scheme.

[1]  Sudarshan P. Bhat,et al.  Solutions to Point-to-Point Control Problems using Laplace Transform Technique , 1990, 1990 American Control Conference.

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

[3]  R. S. Gyurcsik,et al.  A model for rapid thermal processing: achieving uniformity through lamp control , 1991 .

[4]  Dim-Lee Kwong,et al.  Systems-oriented survey of noncontact temperature measurement techniques for rapid thermal processing , 1991, Other Conferences.

[5]  Thomas F. Edgar,et al.  MODELING AND CONTROL OF MICROELECTRONICS MATERIALS PROCESSING , 1992 .

[6]  Michael J. Grimble,et al.  Iterative Learning Control for Deterministic Systems , 1992 .

[7]  Pasquale Lucibello,et al.  State steering by learning for a class of nonlinear control systems , 1994, Autom..

[8]  Y. Chen,et al.  Drag coefficient curve identification of projectiles from flight tests via optimal dynamic fitting , 1997 .

[9]  Evanghelos Zafiriou,et al.  An approach to run-to-run control for rapid thermal processing , 1995, Proceedings of 1995 American Control Conference - ACC'95.

[10]  Yangquan Chen,et al.  Analysis of a high-order iterative learning control algorithm for uncertain nonlinear systems with state delays , 1998, Autom..

[11]  Fred Roozeboom,et al.  Rapid thermal processing systems: A review with emphasis on temperature control , 1990 .

[12]  Giuseppe Oriolo,et al.  Cyclic learning control of chained-form systems with application to car-like robots , 1996 .

[13]  Suguru Arimoto,et al.  Bettering operation of Robots by learning , 1984, J. Field Robotics.

[14]  Tong-heng Lee,et al.  An Iterative Learning Control In Rapid Thermal Processing , 1997 .

[15]  Sudarshan P. Bhat,et al.  Point-to-Point Positioning of Flexible Structures using a Time Domain LQ Smoothness Constraint , 1991, 1991 American Control Conference.