A method for forming a contact of a semiconductor device with reduced step height is disclosed, comprising forming a plurality of gates, forming a buffer layer on each of the gates, forming an insulating layer to fill spaces between the gates, forming strip-shaped photoresist patterns which cross the gates, etching the insulating layer to form first openings using a self-aligning process with the gates and the strip-shaped photoresist patterns as a mask, forming a conductive contact layer to fill the first openings, performing a first chemical mechanical polish (CMP) process to the conductive contact layer, removing the buffer layer, and forming a second chemical mechanical polish (CMP) process to the conductive contact layer.