Method to engineer etch profiles in Si substrate for advanced semiconductor devices
First Claim
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1. A method of fabricating a trench comprising:
- etching a substrate to form an upper portion of a trench, wherein the etching forms a passivation layer on sidewalls of the upper portion of the trench;
etching the substrate to form a rounded lower portion of the trench having a width greater than the upper portion, wherein the passivation layer protects the upper portion from being etched during etching to form the lower portion; and
wherein the upper portion and the rounded lower portion form an inverted keyhole trench.
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Abstract
Structures and methods for forming keyhole shaped regions for isolation and/or stressing the substrate are shown. In a first embodiment, we form an inverted keyhole shaped trench in the substrate in the first opening preferably using a two step etch. Next, we fill the inverted keyhole trench with a material that insulates and/or creates stress on the sidewalls of the inverted keyhole trench. In a second embodiment, we form a keyhole stressor region adjacent to the gate and isolation structures. The keyhole stressor region creates stress near the channel region of the FET to improve FET performance. The stressor region can be filled with an insulator or a semiconductor material.
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Citations
21 Claims
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1. A method of fabricating a trench comprising:
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etching a substrate to form an upper portion of a trench, wherein the etching forms a passivation layer on sidewalls of the upper portion of the trench; etching the substrate to form a rounded lower portion of the trench having a width greater than the upper portion, wherein the passivation layer protects the upper portion from being etched during etching to form the lower portion; and wherein the upper portion and the rounded lower portion form an inverted keyhole trench. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of fabricating a semiconductor device comprising:
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providing a substrate; etching an upper portion of a trench in the substrate, wherein a passivation layer is formed on sidewalls of upper portion of the trench during etching; etching a lower portion of the trench while the passivation layer protects the upper portion, the lower portion comprises a rounded lower portion with a width greater than the upper portion; wherein the upper and lower portions form an inverted keyhole trench; and at least partially filling the inverted keyhole shaped trench with a material to create stress on the sidewalls of the inverted keyhole shaped trench to form a stress region. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A method for forming stressor regions comprising:
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providing a substrate prepared with isolation regions defining an active region and a gate structure on the substrate in the active region; forming trenches in source/drain regions adjacent to the isolation regions and the gate structure, wherein forming the trenches comprises etching upper portions of the trenches in the source/drain regions of the substrate, wherein passivation layers are formed on sidewalls of the upper portions of the trenches during etching, and etching lower portions of the trenches to form rounded lower portions with widths greater than the upper portions, the passivation layers protecting the upper portions during etching to form the lower portions; and filling the trenches with a stress material to form stressor regions, wherein the stressor regions create stress in the substrate under the gate structure. - View Dependent Claims (17, 18, 19, 20, 21)
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Specification