Patent ID: 7923329
Filing Date: 2011-04-12
Classification: H01L

Abstract:
1. A method for manufacturing a semiconductor device, the method comprising: forming vertical transistors in a semiconductor substrate; forming a spin-on-carbon (SOC) film filling a gap between the vertical transistors over the semiconductor substrate; forming a hard mask pattern over the semiconductor substrate, including over the vertical transistors and the SOC film; baking the SOC film to make a surface of the SOC film smooth without a Chemical Mechanical Polishing (CMP) process; etching the SOC film and the semiconductor substrate under the SOC film with the hard mask pattern as a mask to form a bit line trench, wherein a residual SOC film remains on at least a portion of the bit line trench; removing the hard mask pattern; and performing an implant process to form a bit line in a portion of the substrate where the bit line trench contacts the vertical transistors using the residual SOC film as an implant mask.