High Speed Si Etching with ClF[sub 3] Cluster Injection

Abstract

The reactive gas cluster injection process is an etching method that uses a neutral cluster beam without plasma. ClF3‐Ar neutral cluster was generated and the Si etching characteristics with this beam were investigated. ClF3 is very high reactive gas. Adiabatic expansion of a high‐pressure gas through a conical nozzle is utilized for the formation of cluster beams. The source gas was a mixture of ClF3 (6%) with Ar (94%). The etching rate increased with source gas pressure nonlinearly, and the etching rate achieved more than 30 μm/min at 0.85 MPa. Although the irradiation energy was very low (<1 eV/atom or molecule), the chemical etching was enhanced with cluster impacts and the cluster bombarded area on the surface was etched selectively. These results indicated that high speed anisotropic etching with low damage can be realized with the ClF3 cluster injection process.