William Jarrett Campbell

Evaluation of model predictive control in run-to-run processing in semiconductor manufacturing

Many steps in the manufacturing of semiconductors offer no opportunity for real-time measurement of the wafer state, necessitating the use of pre- and post-process measurements of the wafer state in a run-to-run control algorithm. The predominant algorithm in the industry is an extended form of SPC using an EWMA filter to adjust a model parameter vector using the available measurements. This paper evaluates the merits of using an optimal discrete controller relying on a discrete-time constrained state-space process model that incorporates feedforward action using the pre-process measurement and feedback using the post-process measurement, accounts for the process statistics using a noise model and optimal filtering theory, and ensures integral action in the controller by estimating unmeasured disturbances. Comparison to the EWMA algorithm are presented using simulations based on actual plant data from a chemical-mechanical polishing application. The polish process is particularly suitable for the application of such a controller because of the natural method the controller provides for incorporating unmeasured disturbances, like pad and slurry changes, in the control action.

Integration of the APC framework with AMD's Fab25 factory system

This paper discusses the integration and development of advanced process control technologies with AMDs Fab25 factory systems using the Advance Process Control Framework. The Framework is an open software architecture that allows the integration of existing factory systems, such as the manufacturing execution systems, configurable equipment interfaces, recipe management systems, metrology tools, process tools, and add-on sensors, into a system which provides advanced process control specific functionality. The Advanced Process Control Framework project was formulated to enable effective integration of Advanced Process Control applications into a semiconductor facility to improve manufacturing productivity and product yields. The main communication link between the factory system and the Framework is the Configurable Equipment Interface. It interfaces through a specialized component in the framework, the Machine Interface, which converts the factory system communication protocol, ISIS, to the Framework protocol, CORBA. The Framework is a distributed architecture that uses CORBA as a communication protocol between specialized components. A generalized example of how the Framework is integrated into the semiconductor facility is provided, as well as a description of the overall architecture used for process control strategy development. The main development language, Tcl/Tk, provides for increased development and deployment over traditional coding methods.