Variation of polysilicon etch rate depending on the surface condition of the etching reaction chamber

Abstract

X-ray photoelectron spectroscopy (XPS) and optical emission spectroscopy (OES) have been employed to determine the possible cause of etch rate variation in a silicon etching reactor. Samples were prepared to analyze the composition of the surface of the chamber at high and low etch rate of polysilicon. XPS analysis for these samples shows that the surface of the etching reaction chamber is richer in fluorine at lower etch rate which can be restored by the seasoning of the etching chamber with chlorine-based plasma. For the same process condition, it has been known that the etch rate is lower for the lower plasma source power applied. Through analysis of OES measurements, even though the supplied external power is the same, the effective power applied to the plasma seems to be lower when the chamber wall surface is fluorine rich. © 2003 The Electrochemical Society. All rights reserved.