Methods of removing portions of fins by preforming a selectively etchable material in the substrate

1. A method of removing a portion of a fin, comprising:

forming an embedded region of a sacrificial material in a semiconductor substrate at a location where the portion of the fin to be removed will be located;

after forming said embedded region of said sacrificial material, performing at least one first etching process to form a plurality of fin-formation trenches that define said fin, wherein at least a portion of said fin is comprised of said sacrificial material; and

performing at least one second etching process to selectively remove substantially all of said sacrificial material portion of said fin relative to material of said substrate.

2. The method of claim 1 , wherein an entire axial length of said fin is comprised of said sacrificial material.

3. The method of claim 1 , wherein said at least one first etching process is performed with an etch chemistry that is substantially non-selective as between said sacrificial material and said substrate material.

4. The method of claim 3 , wherein said at least one second etching process is performed with an etch chemistry that is highly selective as between said sacrificial material and said substrate material.

5. The method of claim 1 , wherein said substrate is made of silicon and said sacrificial material is silicon-germanium (Si x Ge 1-x ) or amorphous silicon.

6. The method of claim 1 , wherein forming said embedded region of said sacrificial material in said substrate comprises forming a rectangular-shaped region, when viewed from above, of said sacrificial material that extends for less than an entire axial length of said fin.

7. The method of claim 1 , wherein forming said embedded region of said sacrificial material in said substrate comprises forming a rectangular-shaped region, when viewed from above, of said sacrificial material that extends for substantially an entire axial length of said fin.

8. The method of claim 1 , wherein forming said embedded region of said sacrificial material in said substrate comprises:

forming a first patterned masking layer on said substrate, said first patterned masking layer having an opening in a position that corresponds to the location where said portion of the fin to be removed will be located, said opening in said first patterned masking layer exposing a surface of said substrate;

performing at least one first etching process through said opening in said first patterned masking layer to form a sacrificial material trench in said substrate;

forming said sacrificial material so as to over-fill said sacrificial material trench with said sacrificial material; and

performing at least one process operation to remove said first patterned masking layer from above said substrate and to planarize an upper surface of said sacrificial material within said sacrificial material trench with an upper surface of said substrate.

9. The method of claim 8 , further comprising forming a second patterned masking layer above said substrate, wherein said at least one first etching process that is performed to form the plurality of trenches that define said fin is performed though said second patterned masking layer.

10. The method of claim 1 , wherein said at least one first etching process is a Br based reactive ion etching process.

11. The method of claim 10 , wherein said at least one second etching process is an isotropic etching process that is performed using an etch chemistry comprised of HCL or HF/HNO 3 /CH 3 COOH.

12. The method of claim 1 , wherein said at least one first etching process and said at least one second etching process are both anisotropic etching processes.

13. The method of claim 8 , wherein forming said sacrificial material so as to over-fill said sacrificial material trench comprises performing an epitaxial deposition process to form said sacrificial material.

14. A method of removing a portion of a fin, comprising:

forming a first patterned masking layer above a semiconductor substrate, said first patterned masking layer having an opening in a position that corresponds to a location where a portion of the fin to be removed will be located, said opening in said first patterned masking layer exposing a surface of said substrate;

performing at least one first etching process through said opening in said first patterned masking layer to form a sacrificial material trench in said substrate;

forming sacrificial material so as to over-fill said sacrificial material trench with said sacrificial material;

performing at least one process operation to remove said first patterned masking layer from above said substrate and to planarize an upper surface of said sacrificial material within said sacrificial material trench with an upper surface of said substrate;

after performing said at least one process operation, forming a second patterned masking layer above said substrate;

performing at least one second etching process through said second patterned masking layer to form a plurality of fin-formation trenches that define said fin, wherein at least a portion of said fin is comprised of said sacrificial material; and

performing at least one third etching process to selectively remove substantially all of said sacrificial material portion of said fin relative to said substrate.

15. The method of claim 14 , wherein an entire axial length of said fin is comprised of said sacrificial material.

16. The method of claim 14 , wherein said at least one second etching process is performed with an etch chemistry that is substantially non-selective as between said sacrificial material and said substrate material.

17. The method of claim 16 , wherein said at least one third etching process is performed with an etch chemistry that is highly selective as between said sacrificial material and said substrate material.

18. The method of claim 14 , wherein said substrate is made of silicon and said sacrificial material is silicon-germanium (Si x Ge 1-x ) or amorphous silicon.

19. The method of claim 14 , wherein said at least one second etching process is a Br-based reactive ion etching process.

20. The method of claim 19 , wherein said at least one third etching process is an isotropic etching process that is performed using an etch chemistry comprised of HCL or HF/HNO 3 /CH 3 COOH.

21. The method of claim 14 , wherein said at least one second etching process and said at least one third etching process are both anisotropic etching processes.

22. The method of claim 1 , wherein said embedded region of said sacrificial material is formed having an upper surface that is substantially co-planar with an upper surface of said semiconductor substrate.