Single-curvature cavity for semiconductor epitaxy
First Claim
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1. A method for forming a field-effect transistor, the method comprising:
- forming a gate structure that overlaps with a channel region beneath a top surface of a semiconductor fin;
etching the semiconductor fin with an anisotropic etching process to form a cavity having a sidewall with a curved section and a planar section arranged between the curved section and the top surface of the semiconductor fin, wherein the planar section is located adjacent to the channel region in the semiconductor fin; and
etching the semiconductor fin with a conformally isotropic etching process having approximately equal horizontal and vertical etch rates that expands a volume of the cavity without changing an aspect ratio of the cavity and without changing a shape of the curved section and the planar section of the sidewall.
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Abstract
Methods of forming a field-effect transistor and structures for a field-effect transistor. A gate structure is formed that overlaps with a channel region beneath a top surface of a semiconductor fin. The semiconductor fin is etched with an anisotropic etching process to form a cavity having a sidewall with a planar section extending vertically toward the top surface of the semiconductor fin and adjacent to the channel region in the semiconductor fin. The semiconductor fin is then etched with an isotropic etching process that widens the cavity at the top surface while preserving verticality of the planar section.
17 Citations
14 Claims
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1. A method for forming a field-effect transistor, the method comprising:
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forming a gate structure that overlaps with a channel region beneath a top surface of a semiconductor fin; etching the semiconductor fin with an anisotropic etching process to form a cavity having a sidewall with a curved section and a planar section arranged between the curved section and the top surface of the semiconductor fin, wherein the planar section is located adjacent to the channel region in the semiconductor fin; and etching the semiconductor fin with a conformally isotropic etching process having approximately equal horizontal and vertical etch rates that expands a volume of the cavity without changing an aspect ratio of the cavity and without changing a shape of the curved section and the planar section of the sidewall. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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Specification