ANALYTIC MODELS FOR PLASMA-ASSISTED ETCHING OF SEMICONDUCTOR TRENCHES

The etching of semiconductor wafers is modeled for etching by radicals (isotropic etching) and etching by both radicals and vertically incid ent cold ions (anisotropic etching) in a glow-discharge plasma. Explic it analytical expressions for evolving two-dimensional etched surfaces are found by the method of characteristics. These parametric relation s are expressed in terms of the position along the initial exposed waf er surface. Exact surface equations are given for the radical etching with two different ansatz for the evolution equation. The superpositio n of radical etching and etching due to vertically incident, bombardin g ions is solved by approximate analytical expressions for the etched surface. Two-dimensional etched surfaces are displayed graphically for various times.