SEDL / STP / STP960-EB / STP25752S

Profile Control of Plasma Etched Polysilicon Using Implant Doping

Abraham, T
Senior Development EngineerManager, IC Development, Northern Telecom Ltd., Ottawa, Ontario

Theriault, R
Senior Development EngineerManager, IC Development, Northern Telecom Ltd., Ottawa, Ontario

Pages: 16    Published: Jan 1987

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Abstract

The effect of implant doping using phosphorus on the edge profiles of plasma-etched polysilicon was investigated. Unique rounded profiles were obtained with as-implanted samples. The profile curvature showed a strong dependence on the fluorine to chlorine ratio in the etch process. There was good correlation between the lateral etch rate variation across the polysilicon thickness and the doping profile. Electrical line width measurements and SEM micrographs indicated line width control of ±0.3 µm. The step coverage of as-deposited PSG was studied and enhanced coverage was observed as the edge profile curvature was increased.