| CPC H10D 30/66 (2025.01) [H10D 30/6713 (2025.01); H10D 30/6755 (2025.01)] | 8 Claims |
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1. A manufacturing method of a semiconductor device, comprising:
forming a first drift region in a semiconductor substrate;
forming a gate oxide layer on the semiconductor substrate;
forming a gate structure on the gate oxide layer, wherein the first drift region is located at a side of the gate structure; and
forming a first source/drain region in the first drift region, wherein the gate oxide layer comprises:
a first portion, wherein at least a part of the first portion is disposed between the gate structure and the semiconductor substrate in a vertical direction; and
a second portion disposed between the first portion of the gate oxide layer and the first source/drain region in a horizontal direction, wherein the second portion of the gate oxide layer comprises a bottom extending downwards and a first depressed top surface located above the bottom in a vertical direction, and a part of the first drift region is located under the first portion of the gate oxide layer and the second portion of the gate oxide layer in the vertical direction,
wherein a method of forming the first drift region comprises:
forming a first trench in the semiconductor substrate; and
performing a doping process after the first trench is formed for forming the first drift region in the semiconductor substrate, wherein a part of the first drift region is formed under the first trench in the vertical direction and located at two opposite sides of the first trench in the horizontal direction, the gate oxide layer is formed by an oxidation process after the doping process, and a part of the first drift region under the first trench is oxidized by the oxidation process to become at least a part of the second portion of the gate oxide layer.
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