Structure and method for forming a trench MOSFET having self-aligned features
First Claim
1. A method of forming a semiconductor device, comprising:
- defining an exposed surface area of a silicon layer where silicon can be removed;
removing a portion of the silicon layer to form a middle section of a trench extending into the silicon layer from the exposed surface area of the silicon layer;
exposing additional surface areas of the silicon layer where silicon can be removed;
removing additional portions of the silicon layer to form outer sections of the trench, the outer sections of the trench extending into the silicon layer from the additional exposed surface areas of the silicon layer, the middle section of the trench extending deeper into the silicon layer than the outer sections of the trench; and
forming a gate electrode partially filling the trench.
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Abstract
In accordance with an embodiment of the present invention, a semiconductor device is formed as follows. An exposed surface area of a silicon layer where silicon can be removed is defined. A portion of the silicon layer is removed to form a middle section of a trench extending into the silicon layer from the exposed surface area of the silicon layer. Additional exposed surface areas of the silicon layer where silicon can be removed are defined. Additional portions of the silicon layer are removed to form outer sections of the trench such that the outer sections of the trench extend into the silicon layer from the additional exposed surface areas of the silicon layer. The middle section of the trench extends deeper into the silicon layer than the outer sections of the trench.
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Citations
23 Claims
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1. A method of forming a semiconductor device, comprising:
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defining an exposed surface area of a silicon layer where silicon can be removed;
removing a portion of the silicon layer to form a middle section of a trench extending into the silicon layer from the exposed surface area of the silicon layer;
exposing additional surface areas of the silicon layer where silicon can be removed;
removing additional portions of the silicon layer to form outer sections of the trench, the outer sections of the trench extending into the silicon layer from the additional exposed surface areas of the silicon layer, the middle section of the trench extending deeper into the silicon layer than the outer sections of the trench; and
forming a gate electrode partially filling the trench. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method of forming a trench MOSFET, comprising:
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forming a first insulating layer over a silicon layer;
removing predefined portions of the first insulating layer to define isolated exposed surface areas of the silicon layer;
performing a first silicon etch to form a middle section of each of a plurality of trenches extending into the silicon layer from the isolated exposed surface areas of the silicon layer;
isotropically etching remaining regions of the first insulating layer to expose additional surface areas of the silicon layer;
performing a second silicon etch to form outer sections of each trench, the outer sections of the trenches extending into the silicon layer from the additional exposed surface areas of the silicon layer, the middle section of each trench extending deeper into the silicon layer than its outer sections; and
forming a gate electrode partially filling each trench. - View Dependent Claims (18, 19, 20, 21, 22, 23)
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Specification