Profile Distortion Caused by Local Electric Field in Polysilicon Etching

Abstract

The relationships between the local side etch in polysilicon etching and the connection between polysilicon and silicon substrate were investigated. It was found that the local side etch occurs only when the polysilicon and the silicon substrate are connected. Also, when the polysilicon and silicon substrate were connected, the depth of the local side etch was found to be related to the size of the area of the silicon substrate exposed to the plasma because of the fact that the depth increases as the area of exposure of the silicon substrate increases. It appears that electrons are supplied from the plasma to the polysilicon through the connection between the polysilicon and the silicon substrate when the exposed area of the silicon substrate is large, and this electron supply is considered to enhance the local electric field which causes the local pattern distortion.