PROFILE DISTORTION CAUSED BY LOCAL ELECTRIC-FIELD IN POLYSILICON ETCHING

The relationships between the local side etch in polysilicon etching a nd the connection between polysilicon and silicon substrate were inves tigated. It was found that the local side etch occurs only when the po lysilicon and the silicon substrate are connected. Also, when the poly silicon and silicon substrate were connected, the depth of the local s ide etch was found to be related to the size of the area of the silico n substrate exposed to the plasma because of the fact that the depth i ncreases as the area of exposure of the silicon substrate increases. I t appears that electrons are supplied from the plasma to the polysilic on through the connection between the polysilicon and the silicon subs trate when the exposed area of the silicon substrate is large, and thi s electron supply is considered to enhance the local electric field wh ich causes the local pattern distortion.