Abstract: The present invention provides an improved method for forming a memory element having a chalcogenide layer such as Ge2Sb2Te5. A substrate having a dielectric etch stop layer, a chalcogenide layer, an anti-reflective layer and a mask layer is placed in a vacuum chamber having a high density plasma source. At least one chlorine containing gas, such as a mixture of BCl3 and Cl2, is introduced into the vacuum chamber for etching the chalcogenide layer and the anti-reflective layer to the dielectric etch stop layer. The etch process is discontinued based on an endpoint detection system. Upon completion of the etch process, the substrate is removed from the vacuum chamber and the mask layer is stripped from the substrate.

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.