In-Situ Measurement of the Relative Thermal Contributions of Chemical Reactions and Ions During Plasma Etching

Abstract

Plasma etch behavior is often explained in terms of "physical" and "chemical" components: both critically related to surface temperatures generated during plasma etching. In an attempt to measure the chemical etch rate component, a specially prepared, 300mm autonomous temperature sensor wafer was used to simultaneously record dynamic surface temperature during plasma etching of photo resist coated and bare silicon surfaces. Data for N2 / H2, Ar / O2, O2 and Cl2 etching chemistries were then compared with measured resist etch rates and RF sensor wafer data. Although insulation of the temperature sensors from the plasma by the 3 micron resist coating prevented calculation of the etch rate chemical component, the capability of this methodology with resist coatings < 500nm was shown. In addition the use of both RF and temperature sensor wafers to quickly identify and correct semiconductor etch process development issues related to isotropic etch non-uniformity was shown.