Trench confined epitaxially grown device layer(s)
View Patent ↗Trench-confined selective epitaxial growth process in which epitaxial growth of a semiconductor device layer proceeds within the confines of a trench. In embodiments, a trench is fabricated to include a pristine, planar semiconductor seeding surface disposed at the bottom of the trench. Semiconductor regions around the seeding surface may be recessed relative to the seeding surface with Isolation dielectric disposed there on to surround the semiconductor seeding layer and form the trench. In embodiments to form the trench, a sacrificial hardmask fin may be covered in dielectric which is then planarized to expose the hardmask fin, which is then removed to expose the seeding surface. A semiconductor device layer is formed from the seeding surface through selective heteroepitaxy. In embodiments, non-planar devices are formed from the semiconductor device layer by recessing a top surface of the isolation dielectric. In embodiments, non-planar devices CMOS devices having high carrier mobility may be made from the semiconductor device layer.
1. A method of forming a heteroepitaxial device layer on a substrate, the method comprising:
receiving a substrate with a semiconductor seeding surface;
forming a hardmask fin over the seeding surface;
forming an isolation region adjacent the hardmask fin;
forming a trench with the seeding surface at the bottom of the trench by removing the hardmask fin; and
epitaxially growing a semiconductor layer within the trench, the semiconductor layer having at least one of a lattice constant mismatch or CTE mismatch with the semiconductor seeding surface.
2. The method of claim 1 , wherein forming the hardmask fin further comprises
depositing a polycrystalline silicon or a silicon nitride layer over the seeding surface; and
patterning the polycrystalline silicon or silicon nitride layer with an anisotropic etch.
3. The method of claim 2 , wherein forming the hardmask fin further comprises depositing an etch stop layer directly on the seeding surface and depositing the polycrystalline silicon or a silicon nitride layer over the oxide layer.
4. The method of claim 2 , wherein the anisotropic etch forms vertical sidewalls or slightly positively sloped sidewalls, and wherein the hardmask fin has an aspect ratio of at least 5:1.
5. The method of claim 1 , wherein forming the isolation region further comprises:
depositing an isolation dielectric layer over the hardmask fin, and
planarizing the isolation dielectric layer to expose a top surface of the hardmask fin.
6. The method of claim 5 , wherein forming the isolation region further comprises:
etching a portion of the substrate adjacent to the hardmask fin to recess the substrate portion not protected by the hardmask fin relative to the seeding surface; and
depositing the isolation dielectric layer over the recessed substrate surface.
7. The method of claim 1 , further comprising:
planarizing a top surface of the epitaxial device layer with the isolation region; and
recessing the isolation region relative to a top surface of the epitaxial device layer to form a non-planar semiconductor body comprising the epitaxial device layer with the isolation region adjacent to the non-planar semiconductor body.
8. The method of claim of claim 7 , further comprising:
forming a gate dielectric and a gate electrode over at least two opposite sides of the epitaxial device layer for control of carrier conduction between source and drain regions coupled to the device layer.
9. The method of claim 8 , wherein the epitaxial device layer comprises Ge or a III-V binary, ternary, or quaternary semiconductor alloy, and wherein forming the gate dielectric and the gate electrode further comprises etching a sacrificial semiconductor layer disposed between the seeding surface and the epitaxial device layer to expose a bottom surface of the epitaxial device layer; and backfilling the gate dielectric and gate electrode over the bottom surface.