Method for making semiconductor device with selective etching of superlattice to accumulate non-semiconductor atoms

1. A method for making a semiconductor device comprising:

forming a superlattice above a semiconductor layer, the superlattice comprising a plurality of stacked groups of layers, each group of layers comprising a plurality of stacked base semiconductor monolayers defining a base semiconductor portion, and at least one non-semiconductor monolayer constrained within a crystal lattice of adjacent base semiconductor portions;

selectively etching the superlattice to remove semiconductor atoms and cause non-semiconductor atoms to accumulate adjacent the semiconductor layer;

epitaxially growing an active semiconductor device layer above the semiconductor layer and accumulated non-semiconductor atoms after the selective etching; and

forming at least one circuit in the epitaxially grown active semiconductor device layer.

2. The method of claim 1 further comprising forming at least one other superlattice between the semiconductor layer and the superlattice layer, the at least one other superlattice comprising a plurality of stacked groups of layers, each group of layers comprising a plurality of stacked base semiconductor monolayers defining a base semiconductor portion, and at least one non-semiconductor monolayer constrained within a crystal lattice of adjacent base semiconductor portions.

3. The method of claim 1 wherein selectively etching comprises chemical etching.

4. The method of claim 1 wherein selectively etching comprises plasma etching.

5. The method of claim 1 wherein the accumulated non-semiconductor atoms may comprise at least one full monolayer of non-semiconductor atoms.

6. The method of claim 1 wherein forming the at least one circuit comprises forming spaced apart source and drain regions in the active semiconductor device layer, and forming a gate defining a channel region between the spaced apart source and drain regions.

7. The method of claim 1 wherein the at least one non-semiconductor monolayer comprise a non-semiconductor selected from the group consisting of oxygen, nitrogen, fluorine, carbon and carbon-oxygen.

8. The method of claim 1 wherein the base semiconductor layers of the first and second superlattices comprise silicon.

9. A method for making a semiconductor device comprising:

forming first and second superlattices above a semiconductor layer, the first and second superlattices each comprising a plurality of stacked groups of layers, each group of layers comprising a plurality of stacked base semiconductor monolayers defining a base semiconductor portion, and at least one non-semiconductor monolayer constrained within a crystal lattice of adjacent base semiconductor portions;

selectively etching the second superlattice to remove semiconductor atoms and cause non-semiconductor atoms to accumulate adjacent the first superlattice;

epitaxially growing an active semiconductor device layer above the semiconductor layer and accumulated non-semiconductor atoms after the selective etching; and

forming at least one circuit in the epitaxially grown active semiconductor device layer by forming spaced apart source and drain regions in the active semiconductor device layer, and forming a gate defining a channel region between the spaced apart source and drain regions.

10. The method of claim 9 wherein selectively etching comprises chemical etching.

11. The method of claim 9 wherein selectively etching comprises plasma etching.

12. The method of claim 9 wherein the accumulated non-semiconductor atoms may comprise at least one full monolayer of non-semiconductor atoms.

13. The method of claim 9 wherein the at least one non-semiconductor monolayer comprise a non-semiconductor selected from the group consisting of oxygen, nitrogen, fluorine, carbon and carbon-oxygen.

14. The method of claim 9 wherein the base semiconductor layers of the first and second superlattices comprise silicon.

15. A method for making a semiconductor device comprising:

forming a superlattice above a semiconductor layer, the superlattice comprising a plurality of stacked groups of layers, each group of layers comprising a plurality of stacked base silicon monolayers defining a base silicon portion, and at least one oxygen monolayer constrained within a crystal lattice of adjacent base semiconductor portions;

selectively etching the superlattice to remove semiconductor atoms and cause oxygen atoms to accumulate adjacent the semiconductor layer;

epitaxially growing an active semiconductor device layer above the semiconductor layer and accumulated oxygen atoms after the selective etching; and

forming at least one circuit in the epitaxially grown active semiconductor device layer.

16. The method of claim 15 further comprising forming at least one other superlattice between the semiconductor layer and the superlattice layer, the at least one other superlattice comprising a plurality of stacked groups of layers, each group of layers comprising a plurality of stacked base silicon monolayers defining a base silicon portion, and at least one oxygen monolayer constrained within a crystal lattice of adjacent base silicon portions.

17. The method of claim 15 wherein selectively etching comprises chemical etching.

18. The method of claim 15 wherein selectively etching comprises plasma etching.

19. The method of claim 15 wherein the accumulated non-semiconductor atoms may comprise at least one full monolayer of non-semiconductor atoms.

20. The method of claim 15 wherein forming the at least one circuit comprises forming spaced apart source and drain regions in the active semiconductor device layer, and forming a gate defining a channel region between the spaced apart source and drain regions.