Patent ID: 7955927
Filing Date: 2011-06-07
Classification: H01L

Abstract:
1. A method for forming a semiconductor device comprising: providing a semiconductor substrate having a memory array region and a peripheral circuit region; forming a trench in the memory array region; forming an insulation region in the peripheral circuit region to define a first active region and a second active region; forming a doped dielectric layer on a sidewall of the trench; performing a thermal process to diffuse dopants in the doped dielectric layer into the semiconductor substrate, thereby forming a recessed source/drain region; and forming a first gate dielectric layer with a first thickness on a surface of the trench; performing an ion implantation to implant dopants into the first active region; and forming a second gate dielectric layer with a second thickness on a surface of the first active region, and a third gate dielectric layer with a third thickness on a surface of the second active region, wherein the first thickness, the second thickness and the third thickness are different from one another, and the second thickness and the third thickness are different due to the ion implantation step.