Title :
Run by run control of chemical-mechanical polishing
Author :
Boning, Duane ; Moyne, William ; Smith, Taber ; Moyne, James ; Trelfeyan, Roland ; Hurwitz, Arnon ; Sellman, S. ; Taylor, John
Author_Institution :
Microsystems Technol. Lab., MIT, Cambridge, MA, USA
Abstract :
A prototype hardware/software system has been developed and applied to the control of single wafer chemical-mechanical polishing (CMP) processes. The control methodology consists of experimental design to build response surface and linearized control models of the process, and the use of feedback control to change recipe parameters (machine settings) on a lot by lot basis. Acceptable regression models were constructed for average removal rate and nonuniformity, which are calculated based on film thickness measurement at nine points on 8" blanket oxide wafers. For control, an exponentially weighted moving average model adaptation strategy was used, coupled to multivariate recipe generation incorporating user weights on the inputs and outputs, bounds on the input ranges, and discretization in the machine settings. We found that this strategy successfully compensated for substantial drift in the uncontrolled tool\´s removal rate. It was also found that the equipment model generated during the experimental design was surprisingly robust; the same model was effective across more than one CMP tool, and over a several month period
Keywords :
MIMO systems; adaptive control; chemical variables control; control system synthesis; design of experiments; feedback; moving average processes; multivariable control systems; polishing; process control; semiconductor process modelling; statistical process control; average removal rate; blanket oxide wafers; chemical-mechanical polishing; control model robustness; experimental design; exponentially weighted moving average model adaptation strategy; feedback control; film thickness measurement; hardware/software system; linearized control models; machine settings discretization; multivariate recipe generation; regression models; removal rate nonuniformity; response surface models; robust equipment model; run by run control; single wafer CMP process control; Chemical processes; Control systems; Design for experiments; Hardware; Linear feedback control systems; Process control; Response surface methodology; Semiconductor device modeling; Software prototyping; Software systems;
Conference_Titel :
Electronics Manufacturing Technology Symposium, 1995. 'Manufacturing Technologies - Present and Future', Seventeenth IEEE/CPMT International
Conference_Location :
Austin, TX
Print_ISBN :
0-7803-2996-1
DOI :
10.1109/IEMT.1995.526097