Linewidth control and profile contouring of polysilicon by anisotropic plasma etching with Freon 115, (CC₁F₅), and Freon 115/oxygen gas mixtures were investigated utilizing an LFE model 1002-P plana plasma etcher with a laser interferometric endpoint detector. It was found that Freon 115 etches anisotropicly with a reentrant edge profile and good photoresist and Si0₂ etch selectivity. A slight amount of undercutting was observed with overetching and was found to be related to trace amounts of oxygen in the Freon 115 plasma discharge. Freon 115/oxygen mixtures were investigated. It was determined that the polysilicon etch rate and the degree of anisotropy depends strongly on the oxygen concentration. Various combinations of anisotropic/isotropic etch sequences were found to have useful polysilicon edge contouring properties.

Date Published: 5 September 1980
PDF: 8 pages
Proc. SPIE 0221, Developments in Semiconductor Microlithography V, (5 September 1980); doi: 10.1117/12.958624

Published in SPIE Proceedings Vol. 0221:
Developments in Semiconductor Microlithography V
James W. Dey, Editor(s)