Defect capping method for reduced defect density epitaxial articles
A method for forming an epitaxial layer on a substrate surface having crystalline defect or amorphous regions and crystalline non-defect regions includes preferential polishing or etching the crystalline defect or amorphous regions relative to the crystalline non-defect regions to form a decorated substrate surface having surface recess regions. A capping layer is deposited on the decorated substrate surface to cover the crystalline non-defect regions and to at least partially fill the surface recess regions. The capping layer is patterned by removing the capping layer over the crystalline non-defect regions to form exposed non-defect regions while retaining the capping layer in at least a portion of the surface recess regions. Selective epitaxy is then used to form the epitaxial layer, wherein the capping layer in the surface recess regions restricts epitaxial growth of the epitaxial layer over the surface recess regions.
1. A method for forming an epitaxial layer on a substrate comprising a substrate surface having crystalline defect or amorphous regions and crystalline non-defect regions, comprising:
preferential polishing said crystalline defect or amorphous regions relative to said crystalline non-defect regions using chemical mechanical polishing (CMP) to form a decorated substrate surface comprising surface recess regions;
depositing a capping layer on said decorated substrate surface to cover said crystalline non-defect regions and to at least partially fill said surface recess regions;
patterning said capping layer by removing said capping layer over said crystalline non-defect regions to form exposed non-defect regions while retaining said capping layer in at least a portion of said surface recess regions, and
selective epitaxy to form said epitaxial layer, wherein said capping layer in said surface recess regions restricts epitaxial growth of said epitaxial layer over said surface recess regions.
2. The method of claim 1 , further comprising chemical mechanical polishing (CMP) after said selective epitaxy to a top surface of said epitaxial layer to provide atomic level smoothness.
3. The method of claim 1 , further comprising chemical mechanical polishing (CMP) said decorated substrate surface to provide an atomic scale finish before said depositing.
4. The method of claim 1 , wherein said depositing comprises a blanket deposition, and said capping layer provides a masking function for restricting said epitaxial growth of said epitaxial layer over said surface recess regions.
5. The method of claim 4 , wherein said depositing comprises physical, chemical or vapor deposition, or electrochemical or electroless deposition.
6. The method of claim 1 , wherein said patterning comprises chemical mechanical polishing (CMP).
7. The method of claim 1 , wherein said epitaxial layer is a homoepitaxial layer.
8. The method of claim 1 wherein said epitaxial layer is a heteroepitaxial layer.
9. The method of claim 1 , wherein said substrate comprises silicon having a 10 Angstrom to 1 mm thick first Group III-nitride semiconductor layer thereon and said epitaxial layer comprises a second Group III-nitride semiconductor layer.
10. The method of claim 1 , wherein said substrate surface comprises SiC or AlN.
11. The method of claim 1 , wherein an average crystalline defect density throughout said epitaxial layer is ≦10 8 cm −2 .
12. The method of claim 1 , wherein said epitaxial layer comprises a group IV, II-VI, III-V material, or a binary ternary or quaternary alloy of said group II-VI material or said III-V material.
13. The method of claim 1 , wherein a surface of said epitaxial layer has an atomic scale finish with a surface roughness less than 5 Å.
14. The method of claim 1 , wherein said CMP comprises using a slurry including a mixture of chemicals and particles.