Insulated gate type field effect transistor and method of manufacturing the same

A method of manufacturing an insulated gate type field effect transistor, comprising the steps of:

• preparing a first semiconductor substrate;
• forming a first epitaxial layer on said first semiconductor substrate to form a second semiconductor substrate, said first epitaxial layer being a first concentration and a first conductivity type, said first epitaxial layer having a lower concentration than a concentration of said first semiconductor substrate;
• forming a diffusion region in said semiconductor substrate under an oxidizing atmosphere by a thermal diffusion method, said diffusion region being formed after forming said second semiconductor substrate;
• forming a first conductivity type semiconductor layer on a surface of said second semiconductor substrate, formation of said first conductivity type semiconductor layer embedding said diffusion region, said first conductivity type semiconductor layer being said first concentration and said first conductivity type;
• and
• forming at a surface of said first conductivity type semiconductor layer an insulated gate type field effect transistor structure.

A method of manufacturing an insulated gate type field effect transistor, comprising the steps of:

• preparing a first semiconductor substrate;
• forming a first epitaxial layer on said first semiconductor substrate to form a second semiconductor substrate, said first epitaxial layer being a first conductivity type and a first concentration, said first epitaxial layer having a lower concentration than a concentration of said first semiconductor substrate;
• forming a phosphosilicate glass film on said second semiconductor substrate by a chemical vapor deposition method, and performing a thermal treatment to form a phosphorous diffusion region in said second semiconductor substrate;
• forming a first conductivity type semiconductor layer on said second semiconductor substrate after said phosphorous diffusion region is formed;
• and
• forming at a surface of said first conductivity type semiconductor layer an insulated gate type field effect transistor structure, said first conductivity type semiconductor layer being said first conductivity type and said first concentration.

A method of manufacturing an insulated gate type field effect transistor, comprising the steps of:

• preparing a second semiconductor substrate which is subjected to a gettering treatment, said second semiconductor substrate including a first substrate and a first epitaxial layer formed on said first substrate, said first epitaxial layer being a first concentration and a first conductivity type, said first epitaxial layer having a lower concentration than said first substrate;
• doping impurities into said second semiconductor substrate by an ion implantation method and diffusing the implanted impurities by a thermal treatment to form a diffusion region;
• forming a first conductivity type semiconductor layer on said second semiconductor substrate after said diffusion region is formed, said first conductivity type semiconductor layer being said first conductivity type and said first concentration;
• and
• forming at a surface of said first conductivity type semiconductor layer an insulated gate type field effect transistor structure.