Method for fabricating self-aligned trench power semiconductor structure

Abstract

The invention provides a method for manufacturing a self-aligned trench power semiconductor structure. The method comprises the following steps of: a) forming a trench polysilicon grid structure in a silicon base material; b) forming a self-aligned polysilicon extension structure which extends upwards from the trench polysilicon grid structure, wherein the self-aligned polysilicon extension structure is narrower than the trench polysilicon grid structure; c) oxidizing the self-aligned polysilicon extension structure to form a silicon oxide protrusion structure above the trench polysilicon grid structure; and d) forming a spacer structure on the side edge of the silicon oxide protrusion structure to define a source contact window in the silicon base material. In the manufacturing method provided by the invention, a spacing distance between the trench polysilicon grid structure and the source contact window is shortened by using a manufacture procedure of self-alignment, so that the limit of a lithography process can be overcome, yield control of the manufacture procedure can be enhanced, the characteristic uniformity of elements at different positions of a wafer can be improved, the cost is low and the feasibility is high.

Description

technical field [0001] The invention relates to a method for manufacturing a trench type power semiconductor structure, in particular to a method for manufacturing a self-aligned (self-aligned) trench type semiconductor structure. Background technique [0002] Figure 1A and Figure 1C It is a fabrication process of a typical trench power semiconductor structure. Such as Figure 1A As shown, firstly, a gate trench 120 is formed on a silicon substrate 110 . Subsequently, a gate oxide layer 130 is formed along the inner surface of the gate trench 120 . Next, deposit polysilicon material on the surface of the silicon substrate 110 , and remove excess polysilicon material by etching back to form a gate polysilicon structure 140 in the gate trench 120 . [0003] Next, if Figure 1B As shown, dopants are implanted into the silicon substrate 110 by ion implantation to form the body 150 surrounding the gate trench 120 . Then, dopants of different conductivity types are implante...

AI Technical Summary

Problems solved by technology

Limited by the critical dimension of the trench and the contact window and the tolerance of alignment control, the distance between the gate trench 120 and the contact window 180 cannot be shortened arbitrarily, otherwise leakage current will easily occur, resulting in a critical voltage Mutation or avalanche resistance (UIS) ability decreased

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