Abstract: The present invention has an object to provide a semiconductor device that is equipped with a high breakdown voltage transistor of a high junction breakdown voltage characteristic and a low voltage transistor of a high electric current drive characteristic to thereby ensure the element isolation performance in the both transistor forming regions. The semiconductor device is equipped with a high breakdown voltage transistor (a) and low voltage transistor (b) the widths of whose side walls are different from each other. The side walls of the high breakdown voltage transistor (a) each consist of four layers of first side wall film, second side wall film, third side wall film, and fourth side wall film that are formed in such a way that they are laminated from both side surfaces of a gate electrode in directions that are sidewardly remote away from this gate electrode.

Abstract: The semiconductor device according to the invention comprises a semiconductor substrate having a semiconductor integrated circuit on the front face thereof and a micro-defect layer preformed in the inside, wherein the semiconductor substrate is made as thin as 150 ?m or thinner in the thickness from the back face so as to leave the micro-defect layer.

Abstract: The present invention has an object to provide a semiconductor device that is equipped with a high breakdown voltage transistor of a high junction breakdown voltage characteristic and a low voltage transistor of a high electric current drive characteristic to thereby ensure the element isolation performance in the both transistor forming regions. The semiconductor device is equipped with a high breakdown voltage transistor (a) and low voltage transistor (b) the widths of whose side walls are different from each other. The side walls of the high breakdown voltage transistor (a) each consist of four layers of first side wall film, second side wall film, third side wall film, and fourth side wall film that are formed in such a way that they are laminated from both side surfaces of a gate electrode in directions that are sidewardly remote away from this gate electrode.

Abstract: On a p-type semiconductor substrate (well region) there are arranged apart from each other an n-type source region and an n-type drain region, a channel region therebetween, and a gate electrode. A pair of p-type channel diffusion regions doped more heavily than the substrate are formed along the channel boundary between the source region and the drain region and the substrate. The channel diffusion region below the drain region is doped with an n-type impurity to achieve a lower active impurity concentration relative to that in the channel diffusion region below the gate electrode.