A method for controlling a variable parameter during a processing of a semiconductor device includes selecting a beginning and an ending value; selecting a function governing how the parameter is to be transitioned; initializing the parameter to the beginning value; and automatically transitioning the parameter according to the selected function. Another method includes selecting a criterion; determining a beginning value; receiving an input; determining from the input whether the parameter needs to be modified; and modifying the parameter. The methods can control the parameters of a Bosch process such that the steps of etching and plasma deposition are performed alternatingly while keeping the transition points arbitrarily small and providing increased control over the process and the resulting trench wall profile. The method applies to other types of semiconductor processing, including without limitation, other deposition and etching applications or processes.
The present invention is generally directed to plasma state monitoring to control etching processes and across-wafer uniformity, and a system for performing same. In one illustrative embodiment, the method comprises generating a plasma within an etching tool, monitoring at least one characteristic of the generated plasma, and controlling at least one parameter of a plasma etching process performed in the tool based upon the monitored at least one characteristic of the plasma. In another illustrative embodiment, the method comprises generating a plasma within an etch tool, performing a plasma etching process within the etch tool, determining at least one characteristic of the plasma, and controlling at least one parameter of the etching process based upon a comparison of the determined at least one characteristic of the plasma and a target value for the determined at least one characteristic of the plasma.
The present invention provides a method for controlling pressure in a vacuum chamber during a time division multiplexed process. A throttle valve is pre-positioned and held for a predetermined period of time. A process gas is introduced into the vacuum chamber during the associated plasma step (deposition or etching) of the silicon wafer. At the end of the predetermined period of time, the process gas continues to flow with the throttle valve being released from the set position. At this point, the throttle valve is regulated through a proportional derivative and integral control for a period that lasts the remaining time of the associated plasma step.
The present invention provides a method for controlling pressure in a chamber during a time division multiplexed process. A throttle valve is positioned based on an open-loop pressure control algorithm within at least one step of the time division multiplexed etch process. A pressure response of the step is evaluated and compared to a desired pressure response. The throttle valve is then positioned through a proportional, integral and derivative controller step to step of the time division multiplexed etch process based on the evaluation to the desired pressure response.
