A method of forming a silicon dioxide layer on a curved Si surface

摘要

The present invention refers to a method of forming a silicon dioxide layer by thermally oxidizing at least one monocrystalline silicon surface region on a semiconductor substrate, said silicon surface region having a curved surface. The present invention is advantageously applicable for the formation of the collar region in the upper part of the trench of a DRAM (Dynamic Random Acess Memory) cell. The method comprises the steps of providing a semiconductor substrate (1) having at least one monocrystalline silicon surface region having a curved surface, roughening the surface of said at least one monocrystalline silicon surface region so as to produce a layer of porous silicon, and thermally oxidizing (9) said at least one roughened monocrystalline silicon surface.