Patent ID: 9093464
Filing Date: 2015-07-28
Classification: H01L

Abstract:
1. A method for fabricating a small-scale metal-oxide semiconductor (MOS) device comprising: preparing a substrate of a first conductivity type; forming a gate oxide layer on the substrate; forming a gate region on a portion of a top surface of the gate oxide layer; forming a first trench in the substrate along a first side of the gate region and passing through the gate oxide layer, and forming a second trench in the substrate along a second side of the gate region and passing through the gate oxide layer, the first side of the gate region being opposite to the second side of the gate region; forming a first lightly doped drain region and a second lightly doped drain region to substantially fill the first trench and the second trench, respectively, by a selective epitaxial growth, wherein a remaining portion of the gate oxide layer on the substrate allows the selective epitaxial growth to occur substantially within the first trench and the second trench in the substrate; forming a third trench in the substrate overlapping at least a first portion of the first lightly doped drain region and a fourth trench in the substrate overlapping at least a first portion of the second lightly doped drain region; and forming a source region and a drain region in the third trench and the fourth trench, respectively.