Selective etching of silicon nitride over silicon oxide using ClF3/H2 remote plasma

Le résumé fourni par la source

Abstract Precise and selective removal of silicon nitride (SiN x ) over silicon oxide (SiO y ) in a oxide/nitride stack is crucial for a current three dimensional NOT-AND type flash memory fabrication process. In this study, fast and selective isotropic etching of SiN x over SiO y has been investigated using a ClF 3 /H 2 remote plasma in an inductively coupled plasma system. The SiN x etch rate over 80 nm/min with the etch selectivity (SiN x over SiO y ) of ~ 130 was observed under a ClF 3 remote plasma at a room temperature. Furthermore, the addition of H 2 to the ClF 3 resulted in an increase of etching selectivity over 200 while lowering the etch rate of both oxide and nitride due to the reduction of F radicals in the plasma. The time dependent-etch characteristics of ClF 3 , ClF 3 & H 2 remote plasma showed little loading effect during the etching of silicon nitride on oxide/nitride stack wafer with similar etch rate with that of blank nitride wafer.

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