Ym. Cho et P. Gyugyi, CONTROL OF RAPID THERMAL-PROCESSING - A SYSTEM-THEORETIC APPROACH, IEEE transactions on control systems technology, 5(6), 1997, pp. 644-653
Citations number
30
Categorie Soggetti
Controlo Theory & Cybernetics","Robotics & Automatic Control","Engineering, Eletrical & Electronic
In this paper, a framework is given for achieving the tight control of
the wafer temperature essential in rapid thermal processing (RTP) of
semiconductor wafers, Of the various techniques for controlling wafer
temperature in RTP systems, we focus on model-based control since it h
as the greatest potential for attaining the best performance. First, t
he identification of a state-space model, based on the subspace-fittin
g technique, results in an empirical model, Then, convex optimization
is used to obtain an approximation to the desired trajectory, close en
ough to allow high gain feedback controllers to 1) reduce temperature
nonuniformity and 2) accommodate actuator constraints, Subsequently, a
feedback linear quadratic Gaussian (LQG) controller is designed based
on the identified model, The benefits of convex optimization together
with LQG feedback control are demonstrated by experimental results fr
om an RTP system at Stanford University, CA.