This paper develops a model of n-doped polysilicon etching in a SF₆/C₂C1F₅ (Freon 115) plasma using a parallel-plate reactor. Plasmas created using a range, or space, of gas flowrates, pressure and applied R.F. power were monitored using optical emission spectroscopy. Polysilicon etchrates and etch anisotropy were then correlated to the relative intensity of many emission peaks using multiple linear regression techniques. The attempt was made to relate etch anisotropy to species in the bulk plasma that are not suspected to participate in the chemical etching of the polysilicon; ions that enhance the vertical etchrate by ion bombardment relative to the lateral etchrate, along with reactive ionic species. The resulting empirical model contains many factors (individual emission peaks) that may be handled by microprocessor controlled optical emission spectrophotometers to monitor the etching process or to model the feature profile with changes in etching parameters.

Date Published: 15 March 1989
PDF: 6 pages
Proc. SPIE 1037, Monitoring and Control of Plasma-Enhanced Processing of Semiconductors, (15 March 1989); doi: 10.1117/12.951019

Published in SPIE Proceedings Vol. 1037:
Monitoring and Control of Plasma-Enhanced Processing of Semiconductors
James E. Griffiths, Editor(s)