Suitable Trench Shape for Dielectric Isolation
Original Publication Date: 1984-Oct-01
Included in the Prior Art Database: 2005-Feb-05
This article relates to the minimization of surface voids encountered during such CVD (chemical vapor deposition) trench filling processes as polysilicon or oxide filling. Surface voids, by allowing oxidation to occur within the trenches during subsequent processing, generate stresses which, in turn, generate defects. The disclosed technique creates a suitable trench shape by creating a "positive slope" sidewall, thereby eliminating surface voids while also reducing the size and rate of occurrence of any internal voids. By a novel application of the oxide sidewall technology for trench formation, a tapered trench opening is obtained, as shown in Figs. 1 through 3. Subsequent fabrication processes for obtaining a polysilicon filled trench are illustrated by Figs. 4 through 6.