Method of manufacturing a transistor of a semiconductor device

A method of manufacturing a transistor comprising:

• depositing a first insulating layer over a semiconductor substrate;
• forming a trench by etching the first insulating layer and the semiconductor substrate;
• performing a first ion implantation into the semiconductor substrate;
• depositing a second insulating layer and a first conductive layer over the semiconductor substrate on which the trench is formed;
• planarizing the second insulating layer and first conductive layer to form a trench gate;
• depositing a second conductive layer over the trench gate and the semiconductor substrate;
• forming a mask pattern having a width wider than the trench gate over the second conductive layer;
• patterning the second conductive layer, the first insulating layer and an upper portion of the semiconductor substrate using the mask pattern;
• removing the mask pattern;
• performing a second ion implantation using the second conductive layer as a mask to form a source/drain region;
• and
• heat treating the semiconductor substrate to form a silicide layer over the second conductive layer and over an exposed surface portion of the semiconductor substrate.