Patent ID: 8916438

Claim:
A method for fabricating a trench type transistor device, comprising: providing a semiconductor substrate; forming an epitaxial layer on the semiconductor substrate; forming a hard mask layer on the epitaxial layer, the hard mask layer comprising at least an opening; through the opening, etching a gate trench into the epitaxial layer; forming a gate oxide layer in the gate trench; forming a gate within the gate trench, wherein the gate within the gate trench has a top surface that is higher than a top surface of the epitaxial layer; forming a cap layer on the gate; after forming the cap layer, removing the hard mask layer to thereby revealing the top surface of the epitaxial layer; after removing the hard mask layer, performing an oxidation to form a silicon oxide layer at least on the top surface of the epitaxial layer; after forming the silicon oxide layer on the top surface of the epitaxial layer, forming an ion well within the epitaxial layer; forming a source doping region within the ion well; forming a spacer on sidewall of the cap layer and the gate; and self-aligned etching the epitaxial layer using the cap layer and the spacer as an etching hard mask, thereby forming a contact hole.