Method of forming narrow trenches in semiconductor substrates
First Claim
1. A method of forming a trench MOSFET comprising:
- providing a semiconductor wafer of a first conductivity type;
depositing an epitaxial layer of said first conductivity type over said wafer, said epitaxial layer having a lower majority carrier concentration than said wafer;
forming a body region of a second conductivity type within an upper portion of said epitaxial layer;
providing a patterned first masking material layer over said epitaxial layer, said patterned first masking material layer comprising a densified non-doped silica glass layer overlaid by a positive photoresist material, and said patterned first masking material layer comprising a first aperture;
depositing a second masking material layer over said first masking material layer, said second masking material layer comprising a densified non-doped silica glass layer;
etching said second masking material layer until a second aperture is created in said second masking material layer within said first aperture, said second aperture being narrower than said first aperture;
forming a trench in said epitaxial layer by etching said semiconductor wafer through said second aperture; and
removing the first masking material layer and the second masking material layer prior to performing the following steps;
forming an insulating layer lining at least a portion of said trench;
forming a conductive region within said trench adjacent said insulating layer; and
forming a source region of said first conductivity type within an upper portion of said body region and adjacent said trench,wherein said step of forming a source region is performed subsequent to said step of forming a trench.
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Abstract
A method of forming a trench within a semiconductor substrate. The method comprises, for example, the following: (a) providing a semiconductor substrate; (b) providing a patterned first CVD-deposited masking material layer having a first aperture over the semiconductor substrate; (c) depositing a second CVD-deposited masking material layer over the first masking material layer; (d) etching the second masking material layer until a second aperture that is narrower than the first aperture is created in the second masking material within the first aperture; and (e) etching the semiconductor substrate through the second aperture such that a trench is formed in the semiconductor substrate. In preferred embodiments, the method of the present invention is used in the formation of trench MOSFET devices.
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Citations
10 Claims
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1. A method of forming a trench MOSFET comprising:
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providing a semiconductor wafer of a first conductivity type; depositing an epitaxial layer of said first conductivity type over said wafer, said epitaxial layer having a lower majority carrier concentration than said wafer; forming a body region of a second conductivity type within an upper portion of said epitaxial layer; providing a patterned first masking material layer over said epitaxial layer, said patterned first masking material layer comprising a densified non-doped silica glass layer overlaid by a positive photoresist material, and said patterned first masking material layer comprising a first aperture; depositing a second masking material layer over said first masking material layer, said second masking material layer comprising a densified non-doped silica glass layer; etching said second masking material layer until a second aperture is created in said second masking material layer within said first aperture, said second aperture being narrower than said first aperture; forming a trench in said epitaxial layer by etching said semiconductor wafer through said second aperture; and removing the first masking material layer and the second masking material layer prior to performing the following steps; forming an insulating layer lining at least a portion of said trench; forming a conductive region within said trench adjacent said insulating layer; and forming a source region of said first conductivity type within an upper portion of said body region and adjacent said trench, wherein said step of forming a source region is performed subsequent to said step of forming a trench. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification