DRY ETCHING OF THERMAL SIO2 USING SF6-BASED PLASMA FOR VLSI FABRICATION

The plasma etching of thermal SiO2 using a combination of SF6, CHF3 and He was investigated and a process developed on a parallel-plate planar plasma reactor. The etching of SiO2 in fluorocarbon plasmas containing CF4, mixtures of CF4 and O2 and mixtures of CF4 and H2 have been widely investigated and yielded important data about many of the fundamental mechanisms that are operative in plasma processing. SF6 is a gas which is frequently used for the plasma etching of tungsten silicide, polysilicon and PECVD silicon nitride. However, little is reported about its use for the plasma etching of thermal SiO2 in integrated circuit fabrication. This paper reports essential evaluations to characterize the SiO2 plasma etch process using SF6 and its application in the etching and fabrication of a Schottky contact.