Abstract: 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.