INSULATION GATE BIPOLAR TRANSISTOR WITH MULTI-LAYER BUFFER STRUCTURE AND THE MANUFACTURING METHOD

摘要

PURPOSE: In the insulation gate bipolar transistor, the yield voltage during reverse voltage shelter decreases as n+ buffer layer density increases. An insulation gate bipolar transistor is provided which maintains high yield voltage during reverse voltage shelter. CONSTITUTION: Insulation gate bipolar transistor has the buffer layer (110) on the p+ semiconductor panel (100) and the low-density n- epitaxial layer is formed on the buffer layer (110). The buffer layer (110) is divided by the impurity density of each area into the lower part, the first area (111) and the upper part, the second area (112). In the second area (112), n type impurity is doped in high density and in the first area (111) it is doped in much lower impurity density. With the multi-layer structure, the transistor maintains high yield voltage during reverse voltage shelter.