High fidelity patterning employing a fluorohydrocarbon-containing polymer

• US 8,916,054 B2
• Filed: 10/26/2011
• Issued: 12/23/2014
• Est. Priority Date: 10/26/2011
• Status: Expired due to Fees

• Current Assignee: GlobalFoundries, Inc., ZEON Corporation
• Original Assignee: International Business Machines Corporation, ZEON Corporation
• Inventors: Brink, Markus, Engelmann, Sebastian U., Fuller, Nicholas C. M., Guillorn, Michael A., Miyazoe, Hiroyuki, Nakamura, Masahiro
• Primary Examiner(s): Ahmed, Shamim
• Application Number:
  US13/281,749
• Publication Number:
  US 20130108833A1
• Time in Patent Office: 1,154 Days
• Field of Search: 216/41, 216/47, 216/67, 430/313
• US Class Current: 216/47
• CPC Class Codes: G03F 7/091 characterised by antireflection means or light filtering or absorbing means, e.g. anti-halation, contrast enhancement
• CPC Class Codes: G03F 7/094 Multilayer resist systems, e.g. planarising layers
• CPC Class Codes: G03F 7/40 Treatment after imagewise removal, e.g. baking
• CPC Class Codes: H01L 21/0332 characterised by their composition, e.g. multilayer masks, materials
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/31122 of layers not containing Si, e.g. PZT, Al2O3
• CPC Class Codes: H01L 21/31138 by dry-etching
• CPC Class Codes: H01L 21/31144 using masks
• CPC Class Codes: Y10T 428/24479 including variation in thickness

Abstract

A stack of a hard mask layer, a soft mask layer, and a photoresist is formed on a substrate. The photoresist is patterned to include at least one opening. The pattern is transferred into the soft mask layer by an anisotropic etch, which forms a carbon-rich polymer that includes more carbon than fluorine. The carbon-rich polymer can be formed by employing a fluorohydrocarbon-containing plasma generated with fluorohydrocarbon molecules including more hydrogen than fluorine. The carbon-rich polymer coats the sidewalls of the soft mask layer, and prevents widening of the pattern transferred into the soft mask. The photoresist is subsequently removed, and the pattern in the soft mask layer is transferred into the hard mask layer. Sidewalls of the hard mask layer are coated with the carbon-rich polymer to prevent widening of the pattern transferred into the hard mask.

Claims

1. A method of forming a patterned structure comprising:

forming a stack comprising, from bottom to top, a substrate, a hard mask layer that is not carbon-based, a soft mask layer including a carbon-based material, and a photoresist;

lithographically patterning said photoresist; and

transferring a pattern in said photoresist into said soft mask layer employing an anisotropic etch, wherein a carbon-rich polymer including carbon and fluorine is formed on sidewalls around an opening of said soft mask layer, wherein an atomic ratio of carbon to fluorine is greater than 1 within said carbon-rich polymer, wherein said anisotropic etch employs a fluorohydrocarbon-containing plasma, and said carbon-rich polymer is generated by interaction of said fluorohydrocarbon-containing plasma with said soft mask layer, and wherein said fluorohydrocarbon-containing includes ions of C_xH_yF_z, wherein x is an integer selected from 3, 4, 5, and 6, y and z are positive integers, and y is greater than z.

2. The method of Claim 1, further comprising:

removing said photoresist after transferring said pattern into said soft mask layer; and

transferring a pattern in said soft mask layer into said hard mask layer.

3. The method of claim 2, wherein said pattern in said soft mask layer is transferred into said hard mask layer by another anisotropic etch employing another fluorohydrocarbon-containing plasma.

4. The method of claim 3, wherein another carbon-rich polymer contacting sidewalls of said hard mask layer is generated by interaction of said fluorohydrocarbon-containing plasma with said soft mask layer.

5. The method of claim 4, wherein said another carbon-rich polymer contiguously extends over a top surface of said soft mask layer, sidewalls of said soft mask layer, and said sidewalls of said hard mask layer.

6. The method of claim 3, wherein said another fluorohydrocarbon-containing plasma includes ions of C_pH_qF_r, wherein p is an integer selected from 3, 4, 5, and 6, q and r are positive integers, and q is greater than r.

7. The method of claim 3, wherein said stack further comprises another hard mask layer formed between said substrate and said hard mask layer, and said method further comprises:

removing said soft mask layer after said hard mask layer is patterned; and

transferring a pattern in said hard mask layer into said another hard mask layer employing an additional anisotropic etch.

8. The method of claim 1, wherein said carbon-rich polymer includes hydrogen at an atomic concentration that is at least one half of said atomic concentration of carbon in said carbon-rich polymer.

11. The method of claim 1, wherein said another fluorohydrocarbon-containing plasma includes ions of C_xH_yF_z, wherein x is an integer selected from 3, 4, 5, and 6, y and z are positive integers, and y is greater than z.

12. The method of claim 1, wherein said stack further comprises another hard mask layer formed between said substrate and said hard mask layer, and said method further comprises:

removing said soft mask layer after said hard mask layer is patterned; and

transferring a pattern in said hard mask layer into said another hard mask layer employing an additional anisotropic etch.

9. A method of forming a patterned structure comprising:

forming a stack comprising, from bottom to top, a substrate, a hard mask layer that is not carbon-based, a soft mask layer including a carbon-based material, and a photoresist;

lithographically patterning said photoresist;

patterning said soft mask layer by transferring a pattern in said photoresist into said soft mask layer; and

transferring a pattern in said soft mask layer into said hard mask layer employing an anisotropic etch, wherein a carbon-rich polymer including carbon and fluorine is formed contiguously on a top surface of said soft mask layer, on sidewalls of said soft mask layer, and on sidewalls of said hard mask layer, wherein an atomic ratio of carbon to fluorine is greater than 1 within said carbon-rich polymer, wherein said anisotropic etch employs a fluorohydrocarbon-containing plasma, and said carbon-rich polymer is generated by interaction of said fluorohydrocarbon-containing plasma with said soft mask layer, and wherein said fluorohydrocarbon-containing plasma includes ions of C_pH_qF_r, wherein p is an integer selected from 3, 4, 5, and 6, q and r are positive integers, and q is greater than r.

10. The method of Claim 9, wherein said pattern in said photoresist is transferred into said soft mask layer by another anisotropic etch employing another fluorohydrocarbon-containing plasma, and said method further comprises removing said photoresist after transferring said pattern in said photoresist into said soft mask layer.