Method for manufacturing trench gate power devices with shielded gate

Abstract

The invention discloses a method for manufacturing a trench gate power device with a shield gate, which comprises the following steps: step 1, providing a silicon substrate and forming a trench in the silicon substrate; step 2, forming a trench at the bottom of the trench The first silicon oxide layer and the shield gate; Step 3, forming a second silicon oxide layer; Step 4, depositing a BPSG film and performing reflow planarization, and completely filling the top of the trench with the BPSG film and the second silicon oxide layer; Step 5 1. Etching back the silicon oxide to form an isolation dielectric layer between polysilicon composed of the etched back BPSG film and the second silicon oxide layer; step 6, forming a gate dielectric layer and a polysilicon gate on the top of the trench. The invention can reduce the unit structure size of the device and obtain a thin grid dielectric layer, thereby reducing the conduction voltage drop of the device and realizing low-voltage application.

Description

technical field [0001] The invention relates to a method for manufacturing a semiconductor integrated circuit, in particular to a method for manufacturing a trench gate power device with a shield gate (Shield Gate Trench, SGT). Background technique [0002] A trench gate power device with a shield gate needs to form a shield gate at the bottom of the trench gate. The shield gate and the trench gate are generally composed of polysilicon, and the shield gate and the trench gate need to be isolated by an isolation dielectric layer between polysilicon . In the existing method, there are two methods for forming the isolation dielectric layer between polysilicon. The first method is to deposit silicon oxide to fill the top of the shield gate after the shield gate is formed. trenches, and then silicon oxide is etched back to form an isolation dielectric layer between polysilicon; the second method is to form an isolation dielectric layer between polysilicon by using a thermal oxid...

AI Technical Summary

Problems solved by technology

However, the quality of thermal silicon oxide grown on polysilicon is relatively poor, and a sufficiently thick isolation silicon oxide must be obtained by increasing the thickness of the gate silicon oxide; this will affect the threshold voltage (VT) of the device and the switching process of the unclamped inductive load. switching, UIS) capability

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