Method of improving etch uniformity in deep silicon etching

Abstract

A method is disclosed for improving etch uniformity in deep silicon etching of a monocrystalline silicon wafer. Such method includes forming a pad dielectric layer on a wafer including monocrystalline silicon, forming a silicon layer over the pad dielectric layer, and then applying a clamp to an edge of the wafer. The silicon layer is then removed except in areas protected by the clamp. Thereafter, a hardmask layer is applied and patterned on the wafer; and the wafer is then directionally etched with the patterned hardmask to etch trenches in the monocrystalline silicon. In such manner, a source of silicon (in the silicon layer) is provided at the wafer edge, such that the silicon loading is improved. In addition, the silicon layer at the wafer edge forms a blocking layer which prevents formation of black silicon.

Dependencies are inferred from the claim text.