Fin cut profile using fin base liner

Patent metadata

Field	Value
Publication number	US-10985025-B2
Application number	US-201816173331-A
Country	US
Kind code	B2
Filing date	Oct 29, 2018
Priority date	Oct 29, 2018
Publication date	Apr 20, 2021
Grant date	Apr 20, 2021

Abstract

Methods for forming semiconductor fins include forming a protective layer around a base of a hardmask fin on an underlying semiconductor layer. A portion of the hardmask fin is etched away with an etch that is selective to the protective layer. A semiconductor fin is etched from the semiconductor layer using the etched hardmask fin as a mask.

First claim

What is claimed is:

1. A method for forming a semiconductor fin, comprising:
forming a protective layer around a base of a hardmask fin on an underlying semiconductor layer;
etching away a portion of the hardmask fin with an etch that is selective to the protective layer; and
etching a semiconductor fin from the semiconductor layer using the etched hardmask fin as a mask.

2. The method of claim 1 , wherein the protective layer is formed from a hafnium oxide.

3. The method of claim 1 , wherein forming the protective layer comprises:
forming a layer of protective material over the hardmask fin;
forming a layer of planarizing material over the layer of protective material;
etching back the layer of planarizing material to a height that covers a portion of the layer of protective material and leaves a remainder of the layer of protective material exposed;
etching away the exposed protective material, leaving the protective layer; and
etching away the remaining planarizing material.

4. The method of claim 3 , wherein forming the layer of protective material comprises a conformal deposition process.

5. The method of claim 1 , wherein the protective layer comprises a horizontal portion that is formed on a top surface of the underlying semiconductor layer around the hardmask fin and a vertical portion that is formed on sidewalls of the hardmask fin.

6. The method of claim 1 , wherein etching away the portion of the hardmask fin comprises:
forming a mask over the hardmask fin that leaves a portion of the hardmask fin exposed; and
anisotropically etching away the exposed portion of the hardmask fin.

7. The method of claim 6 , wherein anisotropically etching away the exposed portion of the hardmask fin comprises an etch chemistry selected from the group consisting of CF4/CHF3 and CH3F.

8. The method of claim 1 , wherein etching the portion of the hardmask fin leaves a remaining portion of the hardmask fin with substantially vertical sidewalls.

9. The method of claim 1 , further comprising forming a plurality of hardmask fins on the underlying semiconductor layer, wherein forming the protective layer around the base of the hardmask fin comprises forming the protective layer around the base of all of the plurality of hardmask fins.

10. The method of claim 9 , wherein forming the protective layer around the base of the plurality of hardmask fins comprises forming the protective layer on the top surface of the underlying substrate layer between the plurality of hardmask fins.

11. A method for forming semiconductor fins, comprising:
forming a protective layer around a base of a plurality of hardmask fins on an underlying semiconductor layer and on a top surface of the underlying semiconductor layer, between the plurality of hardmask fins;
forming a mask over the hardmask fin that leaves a portion of the hardmask fin exposed;
anisotropically etching away the exposed portion of the hardmask fin with an etch that is selective to the protective layer, leaving a remaining portion of the hardmask fin with substantially vertical sidewalls;
etching away the mask; and
etching semiconductor fins from the semiconductor layer using the etched hardmask fins as a mask.

12. The method of claim 11 , wherein the protective layer is formed from a hafnium oxide.

13. The method of claim 11 , wherein forming the protective layer comprises:
forming a layer of protective material over the hardmask fins;
forming a layer of planarizing material over the layer of protective material;
etching back the layer of planarizing material to a height that covers a portion of the layer of protective material and leaves a remainder of the layer of protective material exposed;
etching away the exposed protective material, leaving the protective layer; and
etching away the remaining planarizing material.

14. The method of claim 13 , wherein forming the layer of protective material comprises a conformal deposition process.

15. The method of claim 11 , wherein the protective layer comprises a vertical portion that is formed on sidewalls of the plurality of hardmask fins.

16. The method of claim 11 , wherein anisotropically etching away the exposed portion of the hardmask fin comprises an etch chemistry selected from the group consisting of CF4/CHF3 and CH3F.

17. A method for forming semiconductor fins, comprising:
forming a protective hafnium oxide layer around a base of a plurality of hardmask fins on an underlying semiconductor layer and on a top surface of the underlying semiconductor layer, between the plurality of hardmask fins, comprising a vertical portion on sidewalls of the plurality of hardmask fins;
forming a mask over the hardmask fin that leaves a portion of the hardmask fin exposed;
anisotropically etching away the exposed portion of the hardmask fin with an etch that is selective to the hafnium oxide layer, leaving a remaining portion of the hardmask fin with substantially vertical sidewalls;
etching away the mask; and
etching semiconductor fins from the semiconductor layer using the etched hardmask fins as a mask.

18. The method of claim 17 , wherein forming the protective hafnium oxide layer comprises:
forming a layer of hafnium oxide over the hardmask fins;
forming a layer of planarizing material over the hafnium oxide layer;
etching back the layer of planarizing material to a height that covers a portion of the layer of hafnium oxide and leaves a remainder of the layer of hafnium oxide exposed;
etching away the exposed remainder of the hafnium oxide layer, leaving the covered portion of the hafnium oxide layer; and
etching away the remaining planarizing material.

19. The method of claim 18 , wherein forming the layer of hafnium oxide material comprises a conformal deposition process.

20. The method of claim 17 , wherein anisotropically etching away the exposed portion of the hardmask fin comprises an etch chemistry selected from the group consisting of CF4/CHF3 and CH3F.

Assignees

• IBM

Inventors

• Miller Eric R
• Sieg Stuart A
• Mignot Yann
• Seshadri Indira
• Waskiewicz Christopher J

Classifications

• H10P50/694

  characterised by their behaviour during the process, e.g. soluble masks or redeposited masks · CPC title

• H10P50/695 Primary

  characterised by the process involved to create the mask, e.g. lift-off masks or sidewalls or to modify the mask · CPC title

• H10P76/4085

  characterised by the processes involved to create the masks · CPC title

• H10D30/024 Primary

  of fin field-effect transistors [FinFET] · CPC title

• H10D84/0158

  the components including FinFETs · CPC title