Single Silicon Etching Profile Simulation

Abstract

Single Si etching profile by Cl2 and a mixture of Cl2 and CHF3 are discussed in terms of experimentation and simulation. A microprobe Auger analysis of a trench side wall has proven that the bombardment of obliquely impinging ions to a side wall leads to both concave and tailed features. In the case of a mixture of Cl2 and CHF3, the polymer film produced by CHF3 protects the side wall from species impinging from an inclined direction. Furthermore, the difference in the polymer sputtering rate, resulting from subsequently impinging ions between the tailed part and the flat bottom regions improves the tailed part to the rectangular bottom. A profile simulation supports the idea that obliquely impinging species, polymer deposition and sputtering of a polymer are important factors in determining the single Si etching profile.