Author/Authors :
A. Tay، نويسنده , , W.K. Ho، نويسنده , , C.D. Schaper
and L.L. Lee، نويسنده ,
Title Of Article :
Constraint feedforward control for
thermal processing of quartz
photomasks in microelectronics
manufacturing
Latin Abstract :
A feedforward control scheme is designed to improve performance of conductive heating systems used for lithography in
microelectronics processing.It minimizes the loading effects induced by the common processing condition of placement of a quartz
photomask at ambient temperature on a bake plate at processing temperature.The feedforward control strategy is a model-based
method using linear programming to minimize the worst-case deviation from a nominal temperature set-point during the load disturbance
condition.This results in a predictive controller that performs a pre-determined heating sequence prior to the arrival of
the substrate as part of the resulting feedforward/feedback strategy to eliminate the load disturbance.This procedure is based on an
empirical model generated from data obtained during closed-loop operation.It is easy to design and implement for conventional
thermal processing equipment.Experimental results are performed for two commercial bake plates and depict an order-of-magnitude
improvement in the settling time and the integral-square temperature error between the optimal predictive controller and a
feedback controller for a typical load disturbance.
NaturalLanguageKeyword :
Feedforward Control , semiconductor manufacturing , Temperature control
JournalTitle :
Studia Iranica
