Formation of isolation film of semiconductor device involves forming first high-density plasma oxide film in trench, performing etch-back process using mixture of dicarbon hexafluoride gas and oxygen gas, and forming second oxide film

摘要

#CMT# #/CMT# An isolation film of a semiconductor device is formed by forming a trench in a semiconductor substrate (20); forming a first high-density plasma (HDP) oxide film in the formed trench; performing an etch-back process using a mixture of dicarbon hexafluoride gas and oxygen gas to form a vertical sidewall in the first oxide film; and forming a second HDP oxide film on the resulting structure. #CMT#USE : #/CMT# For forming an isolation film of a semiconductor device. #CMT#ADVANTAGE : #/CMT# The fluorine ions that can be diffused into the interface between the isolation film and the trench or between layers of the isolation film in an isolation film formation process, are prevented from degrading the characteristics of the resulting device. Characteristics of a device can be improved since diffusion of fluorine ions in the fluorosilicon glass film formed on the first HDP oxide film is minimized. #CMT#DESCRIPTION OF DRAWINGS : #/CMT# The figure is a cross-sectional view for forming an isolation film in a semiconductor device. 20 : Semiconductor substrate 24 : Pad oxide film 26 : Sidewall oxide films 28a : First HDP oxide film 28b : Second HDP oxide film #CMT#INORGANIC CHEMISTRY : #/CMT# Preferred Process: The etch- back process is performed under process condition where dicarbon hexafluoride (C 2F 6) gas flow is 50-200 sccm, oxygen gas flow is 200-500 sccm, a hydrogen fluoride power is 500-1000 W, and a LF power is 3000-4000 W. Sidewall oxide films (26) are formed on the sidewalls of the trenches by an oxidization process, after the trenches are formed. The first HDP oxide film (28a) is formed at silane gas flow of 10-100 sccm, oxygen gas flow of 10-100 sccm, helium gas flow of 100-1000 sccm, hydrogen gas flow of 50-1000 sccm, LF power of 1000-10000 W, and HF power of 500-5000 W. The second HDP oxide film (28b) is formed using the process condition as those of the first HDP oxide film. A polishing process is performed until the semiconductor substrate is exposed, after the second HDP oxide film is formed.