Complementary MOSFET device and method of manufacturing the same

A method of manufacturing a semiconductor device comprising the steps of forming a semiconductor substrate of one conductivity type;

• forming a well layer of the opposite conductivity type in said semiconductor substrate;
• forming a first MOS transistor of one channel type comprising first drain and source regions in said substrate outside said well layer;
• forming a second MOS transistor of opposite channel type comprising second drain and source regions in said well layer, said substrate and said well layer respectively constituting, in the presence of impulse noise, the base region of first and second lateral parasitic bipolar transistors and the base region of first and second vertical parasitic bipolar transistors;
• and heating said semiconductor substrate in an inert atmosphere and cooling said substrate rapidly, after gate oxide films of said first and second MOS transistors have been formed, sufficiently to assure that the product of the current amplification factors B.sub.1 of at least one of said lateral parasitic bipolar transistors and B.sub.2 of at least one of said vertical parasitic bipolar transistors is smaller than 1.

A method of manufacturing a semiconductor device comprising the steps of forming a semiconductor substrate of one conductivity type;

• forming a well layer of the opposite conductivity type in said semiconductor substrate;
• forming a first MOS transistor of one channel type comprising first drain and source regions in said substrate outside said well layer;
• forming a second MOS transistor of opposite channel type comprising second drain and source regions in said well layer, said substrate and said well layer respectively constituting, in the presence of impulse noise, the base region of first and second lateral parasitic bipolar transistors and the base region of first and second vertical parasitic bipolar transistors;
• and heating during the formation of said semiconductor substrate, a semiconductor wafer from which said substrate is formed to 1050.degree. C. to 1150.degree. C. so as to adjust the resistivity of said wafer to assure that the product of the current amplification factors B.sub.1 of at least one of said lateral parasitic bipolar transistors and B.sub.2 of at least one of said vertical parasitic bipolar transistors is smaller than 1.