Method of fabricating a thick oxide feature on a semiconductor wafer

A method of fabricating a thick oxide feature on a semiconductor wafer, the method comprising:

• forming a oxide layer having a thickness of at least six micrometers;
• depositing and patterning a photoresist layer on the oxide layer;
• performing a first timed etch segment of the photoresist layer and the oxide layer, followed by a first pause during which an etching process is halted and byproducts of the etching process are evacuated;
• and
• performing a final etch segment of the photoresist layer and the oxide layer that stops on an etch stop layer.

A method of fabricating a thick silicon oxide feature on a semiconductor wafer, the method comprising:

• forming a silicon oxide layer having a thickness of at least six micrometers, the silicon oxide layer having a first etch rate of X with a given etchant;
• depositing a photoresist layer on the silicon oxide layer, the photoresist layer having a second etch rate of Y with the given etchant, wherein the ratio of X:Y is less than 4:1;
• prior to etching the photoresist layer and the silicon oxide layer using the etchant, patterning the photoresist layer with a grayscale mask;
• and
• etching the photoresist layer and the silicon oxide layer using a plasma etching process to form the thick silicon oxide feature, wherein the etching is performed in a plurality of etch segments that are separated by pauses during which the plasma etching process is halted and the byproducts of the plasma etching process are evacuated.