Method for Manufacturing Insulated Gate Bipolar Transistor IGBT

A method for manufacturing an Insulated Gate Bipolar Transistor, IGBT, comprising:

• forming oxide layers on surfaces of the front and the back of an N-type substrate, wherein the oxide layers comprise a first oxide layer and a second oxide layer, the first oxide layer is the oxide layer overlying the surface of the front of the N-type substrate, and the second oxide layer is the oxide layer overlying the surface of the back of the N-type substrate;
• forming a buffer layer located in the surface of the back of the N-type substrate by implanting N-type impurities and diffusing at high temperature;
• forming protection layers on surfaces of the first oxide layer and the second oxide layer;
• removing the protection layer and the first oxide layer overlying the front of the N-type substrate while reserving the second oxide layer and the protection layer located on the surface of the second oxide layer for protection of the back of the N-type substrate;
• forming a front IGBT structure located on and in the surface of the front of the N-type substrate in a preset first process flow and applying a protection film on a surface of the front IGBT structure for protection of the front IGBT structure;
• removing the protection layer and the second oxide layer overlying the back of the N-type substrate to expose a surface of the buffer layer;
• forming a back IGBT structure located in the surface of the buffer layer in a preset second process flow;
• forming a back metal layer located on a surface of the back IGBT structure in a preset third process flow;
• and
• removing the protection film overlying the surface of the front IGBT structure.