Patent ID: 7354868

Claim:
In a method of fabricating a semiconductor device comprising the sequential steps of: (a) sequentially forming an alloy layer and a material layer on a semiconductor substrate, wherein the alloy layer comprises a silicon-germanium alloy such that the percentage of germanium atoms in the silicon-germanium alloy ranges from greater than 0 to about 99% relative to the percentage of silicon atoms; (b) sequentially forming a mask layer and a photoresist layer on the material layer; (c) performing a photolithography process on the photoresist layer to form photoresist patterns on the mask layer; (d) performing an etching process on the mask layer using the photoresist patterns as an etching mask to form mask patterns; (e) removing the photoresist patterns; (f) sequentially performing an etching process on the material layer, the alloy layer and the substrate using the mask patterns as an etching mask to form a trench that extends into the substrate and which exposes a sectional surface of the alloy layer; (g) removing the mask patterns to form a semiconductor structure; and (h) thereafter performing a cleaning process on the semiconductor structure; the improvement comprising: performing step (h) using an aqueous solution of diluted ammonia and peroxide mixture (APM) wherein the volume ratios of ammonium hydroxide (NH 4 OH), hydrogen peroxide (H 2 O 2 ), and deionized water (DI-water) in the aqueous solution of diluted APM are in the range of about 1:0.5Ëœ20:300 Ëœ2000, respectively.