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

Patent metadata

Field	Value
Publication number	US-9362133-B2
Application number	US-201314101901-A
Country	US
Kind code	B2
Filing date	Dec 10, 2013
Priority date	Dec 14, 2012
Publication date	Jun 7, 2016
Grant date	Jun 7, 2016

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.

First claim

What is claimed is:

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 CF 4 and Ar at about 5 sccm and about 100 sccm, respectively; and
flowing CHF 3 and CF 4 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 CF 4 and Ar occurs for about 10 seconds, and flowing CHF 3 and CF 4 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.

Assignees

• Lam Res Corp

Inventors

• Shamma Nader
• Van Schravendijk Bart
• Reddy Sirish
• Ji Chunhai

Classifications

• H10P95/064

  the removal being chemical etching · CPC title

• H10P76/4088

  Processes for improving the resolution of the masks · CPC title

• H10P76/4085

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

• H10P50/287

  by chemical means · CPC title

• H10P50/285

  of materials not containing Si, e.g. PZT or Al2O3 · CPC title