Semiconductor device having MOS transistor

#1. Field of the Invention

#The present invention relates generally to semiconductor devices and a method of manufacturing the same and, more particularly, to a semiconductor device having an MOS (Metal-Oxide-Semiconductor) transistor and a manufacturing method thereof.

#2. Description of the Background Art

#FIG. 1 is a cross-sectional view showing a semiconductor device including a P channel MOS transistor according to a first embodiment of the present invention.

#FIGS. 2 through 9 are cross-sectional views showing the first to eighth steps of manufacturing the semiconductor device of the first embodiment shown in FIG. 1.

#FIG. 10 is a graph showing the relation between the diffusion depth immediately after implantation and nitrogen concentration in the nitrogen implantation step shown in FIG. 7.

#Embodiments of the present invention will be described in the following with reference to the figures.

#FIG. 1 is a cross-sectional view showing a semiconductor device including a P channel MOS transistor according to a first embodiment of the present invention.

#Referring to FIG. 1, in the semiconductor device according to the first embodiment, an insulation oxide film 2 is formed at a predetermined region on the main surface of an N type silicon substrate 1. Source/drain regions 6a and 6b are formed with a predetermined distance therebetween to sandwich a channel region 10 on the main surface of silicon substrate 1 surrounded by insulation oxide film 2. A gate electrode 4 formed of a polycrystalline silicon film including impurity is formed on a channel region 10 with a gate oxide film 3 having the thickness of 500-2000 .ANG. posed therebetween. Sidewall oxide films 5 are formed at both sidewall portions of gate electrode 4.