Method for forming a mask by etching conformal film on patterned ashable hardmask

• US 9,362,133 B2
• Filed: 12/10/2013
• Issued: 06/07/2016
• Est. Priority Date: 12/14/2012
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Shamma, Nader, van Schravendijk, Bart, Reddy, Sirish, Ji, Chunhai
• Primary Examiner(s): Jung, Michael
• Application Number:
  US14/101,901
• Publication Number:
  US 20140170853A1
• Time in Patent Office: 910 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: H01J 2237/334 Etching
• CPC Class Codes: H01J 37/32082 Radio frequency generated discharge H01J37/32357, H01J37/32366, H01J37/32394 and H01J37/32403 take precedence
• CPC Class Codes: H01J 37/321 the radio frequency energy being inductively coupled to the plasma
• CPC Class Codes: H01J 37/32449 Gas control, e.g. control of the gas flow
• CPC Class Codes: H01L 21/02115 the material being carbon, e.g. alpha-C, diamond or hydrogen doped carbon
• CPC Class Codes: H01L 21/02164 the material being a silicon oxide, e.g. SiO2
• CPC Class Codes: H01L 21/02274 in the presence of a plasma [PECVD]
• CPC Class Codes: H01L 21/0337 characterised by the process involved to create the mask, e.g. lift-off masks, sidewalls, or to modify the mask, e.g. pre-treatment, post-treatment
• CPC Class Codes: H01L 21/0338 Process specially adapted to improve the resolution of the mask
• CPC Class Codes: H01L 21/31055 the removal being a chemical etching step, e.g. dry etching etching per se H01L21/311
• CPC Class Codes: H01L 21/311 Etching the insulating layers by chemical or physical means H01L21/31058 takes precedence
• CPC Class Codes: H01L 21/31111 by chemical means
• 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 21/67069 for drying etching

Abstract

Methods and apparatuses for multiple patterning using image reversal are provided. The methods may include depositing gap-fill ashable hardmasks using a deposition-etch-ash method to fill gaps in a pattern of a semiconductor substrate and eliminating spacer etching steps using a single-etch planarization method. Such methods may be performed for double patterning, multiple patterning, and two dimensional patterning techniques in semiconductor fabrication.

Claims

1. A method of processing a semiconductor substrate, the method comprising:

transferring a pattern from an overlying photoresist to a core amorphous carbon layer;

depositing a conformal film over the patterned core amorphous carbon layer on the semiconductor substrate;

depositing a gap-fill amorphous carbon layer over the conformal film;

planarizing the semiconductor substrate with a process that etches both the conformal film and the gap-fill amorphous carbon layer to remove the conformal film over the core amorphous carbon layer while leaving the conformal film deposited between the core amorphous carbon layer and the gap-fill amorphous carbon layer; and

selectively etching the conformal film to form a mask.

2. The method of claim 1, wherein the semiconductor substrate is planarized by

flowing oxygen and helium at about 20 sccm and about 200 sccm, respectively;

exposing the semiconductor substrate to an aqueous hydrofluoric acid solution;

flowing CF₄ and Ar at about 5 sccm and about 100 sccm, respectively; and

flowing CHF₃ and CF₄ at about 15 sccm and about 80 sccm, respectively.

3. The method of claim 2, wherein flowing oxygen and helium occurs for about 30 seconds, flowing CF₄ and Ar occurs for about 10 seconds, and flowing CHF₃ and CF₄ occurs for about 30 seconds.

4. The method of claim 1, wherein the semiconductor substrate is planarized at a temperature between about 10°

C. and about 50°

C. and a pressure between about 2 Torr and about 20 Torr.

5. The method of claim 1, wherein the semiconductor substrate is planarized using chemical mechanical planarization.

6. The method of claim 1, wherein the gap-fill amorphous carbon layer is deposited by

(a) flowing a hydrocarbon using plasma enhanced chemical vapor deposition until a gap entry width between features in the pattern is reduced,

(b) directionally sputtering ions generated from a plasma to anisotropically etch the semiconductor substrate with a dominant anisotropic axis substantially perpendicular to the semiconductor substrate,

(c) repeating X cycles of (a) and (b), wherein X is a positive integer, and

(d) ashing the semiconductor substrate to remove localized build-up of carbon film on a surface of the semiconductor substrate.

7. The method of claim 6, wherein the hydrocarbon is methane, acetylene, or propylene.

8. The method of claim 1, wherein the pattern further comprises features with aspect ratios between about 1:

1 and about 5;

1.

9. The method of claim 1, further comprising patterning a target layer with the mask.

10. The method of claim 1, further comprising:

prior to transferring a pattern from an overlying photoresist to a core amorphous carbon layer, transferring the pattern from an overlying photoresist to a bottom anti-reflective layer and cap layer simultaneously by pulsing power.

11. A method of processing a semiconductor substrate, the method comprising:

transferring a pattern from a overlying first photoresist to a core first amorphous carbon layer in a first dimension;

depositing a first conformal film over the patterned core first amorphous carbon layer on the semiconductor substrate;

depositing a second amorphous carbon layer over the first conformal film;

selectively etching the second amorphous carbon layer and the core first amorphous carbon layer to expose the patterned first conformal film;

etching an underlying etch stop layer using the patterned first conformal film;

depositing a gap-fill third amorphous carbon layer;

depositing and lithographically defining a second photoresist in a second dimension;

depositing a second conformal film over the second patterned photoresist;

selectively etching the second conformal film to expose the second patterned photoresist;

selectively etching the second patterned photoresist;

selectively etching the gap-fill third amorphous carbon layer; and

selectively etching an underlying cap layer to form a two-dimensional mask.

12. The method of claim 11, further comprising:

depositing and lithographically defining a third photoresist layer on the second amorphous carbon layer to form a block mask; and

selectively etching the second AHM layer using the block mask.

13. The method of claim 11, wherein depositing the gap-fill third amorphous carbon layer further comprises

(a) flowing a hydrocarbon using plasma enhanced chemical vapor deposition until a gap entry width between features in the pattern is reduced,

(b) anisotropically etching the semiconductor substrate with a dominant anisotropic axis substantially perpendicular to the semiconductor substrate,

(c) repeating X cycles of (a) and (b), wherein X is a positive integer, and

(d) ashing the semiconductor substrate to remove localized build-up of carbon film on the surface.

14. The method of claim 13, wherein the hydrocarbon is methane, acetylene, or propylene.

15. The method of claim 11, wherein the second pattern further comprises features with aspect ratios between about 1:

1 and about 5;

1.

16. The method of claim 11, further comprising patterning a target layer with the two-dimensional mask.

17. The method of claim 11, wherein the second conformal film is deposited at a temperature less than about 80°

C.