Method for sidewall spacer line doubling using atomic layer deposition of a titanium oxide

• US 8,623,770 B1
• Filed: 02/21/2013
• Issued: 01/07/2014
• Est. Priority Date: 02/21/2013
• Status: Expired due to Fees

• Current Assignee: Western Digital Technologies Incorporated (Western Digital Corporation)
• Original Assignee: HGST Netherlands B.V. (Western Digital Corporation)
• Inventors: Lille, Jeffrey S., Patel, Kanaiyalal Chaturdas, Gao, He
• Primary Examiner(s): Ghyka, Alexander
• Application Number:
  US13/772,669
• Time in Patent Office: 320 Days
• Field of Search: 438/696, 438/701, 438/785
• US Class Current: 438/701
• CPC Class Codes: H01L 21/02186 the material containing titanium, e.g. TiO2
• CPC Class Codes: H01L 21/0228 deposition by cyclic CVD, e.g. ALD, ALE, pulsed CVD
• 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

Abstract

A method for sidewall spacer line doubling uses thermal atomic layer deposition (ALD) of a titanium oxide (TiOx) spacer layer. A hardmask layer is deposited on a suitable substrate. A mandrel layer of diamond-like carbon (DLC) is deposited on the hardmask layer and patterned into stripes with tops and sidewalls. A layer of TiOx is deposited, by thermal ALD without the assistance of plasma or ozone, on the tops and sidewalls of the mandrel stripes. Thermal ALD of the TiO₂, without energy assistance by plasma or ozone, has been found to cause no damage to the DLC mandrel stripes. After removal of the TiOx from the tops of the mandrel stripes and removal of the mandrel stripes, stripes of TiO₂ are left on the hardmask layer and may be used as an etch mask to transfer the pattern into the hardmask layer.

Claims

1. A method for sidewall spacer line doubling on a substrate comprising:

providing a substrate;

depositing on the substrate a hardmask layer;

depositing on the hardmask layer a mandrel layer;

patterning the mandrel layer into a plurality of stripes on the hardmask layer, the mandrel stripes having tops and sidewalls;

depositing, by thermal atomic layer deposition without plasma assistance and without ozone assistance, a titanium oxide spacer layer on the tops and sidewalls of the mandrel stripes and on the hardmask layer between the mandrel stripes;

etching away the spacer layer on the tops of the mandrel stripes and on the hardmask layer between the mandrel stripes, leaving the mandrel stripes and sidewall spacers;

etching away the mandrel stripes, leaving stripes of sidewall spacers on the hardmask layer;

etching away the hardmask, using the stripes of sidewall spacers as an etch mask; and

removing the stripes of sidewall spacers, leaving stripes of hardmask layer on the substrate.

2. The method of claim 1 wherein depositing on the hardmask layer a mandrel layer comprises depositing a layer of diamond-like carbon (DLC).

3. The method of claim 1 wherein etching away the spacer material on the tops of the mandrel stripes and on the hardmask layer between the mandrel stripes comprises etching by one of Ar ion beam etching and reactive ion etching (RIE) with an etchant gas containing one or both of fluorine and chlorine.

4. The method of claim 1 wherein etching away the mandrel stripes comprises etching by reactive ion etching (RIE) with an etchant gas containing one or both of oxygen and hydrogen.

5. The method of claim 1 further comprising:

after depositing the hardmask layer, depositing a transfer layer on the hardmask layer;

after etching away the mandrel stripes, leaving stripes of sidewall spacer material on the transfer layer, etching away the transfer layer using the stripes of sidewall spacers as an etch mask, leaving stripes of sidewall spacers on stripes of transfer layer; and

then etching away the hardmask, using the stripes of sidewall spacers on the stripes of transfer layer as an etch mask.

6. The method of claim 1 further comprising, after removing the stripes of sidewall spacers:

etching the substrate, using the stripes of hardmask layer as an etch mask; and

removing the stripes of hardmask layer.

7. The method of claim 1 wherein the mandrel stripes have a pitch in a direction parallel to the substrate and orthogonal to the mandrel stripes of 2p₀ and the sidewall spacer stripes have a pitch in a direction parallel to the substrate and orthogonal to the sidewall spacer stripes of p₀.

8. The method of claim 1 wherein the mandrel stripes have a width w, and wherein depositing the spacer layer comprises depositing the spacer layer to a thickness t, wherein t is approximately equal to p₀−

w.

9. The method of claim 1 wherein patterning the mandrel layer into a plurality of stripes comprises patterning the mandrel layer into a pattern selected from parallel generally straight stripes, generally radial stripes, and generally concentric circular stripes.

10. A method for sidewall spacer line doubling on a substrate comprising:

providing a substrate;

depositing on the substrate a hardmask layer;

depositing on the hardmask layer a diamond-like carbon (DLC) layer;

patterning the DLC layer into a plurality of stripes on the hardmask layer, the DLC stripes having tops and sidewalls;

depositing, while the substrate is at a temperature between 100 and 300°

C., by atomic layer deposition without plasma assistance and without ozone assistance, a spacer layer consisting essentially of titanium dioxide on the tops and sidewalls of the DLC stripes and on the hardmask layer between the DLC stripes;

etching away the spacer layer on the tops of the DLC stripes and on the hardmask layer between the DLC stripes, leaving the DLC stripes and sidewall spacers; and

etching away the DLC stripes, leaving stripes of sidewall spacers on the hardmask layer;

etching away the hardmask, using the stripes of sidewall spacers as an etch mask; and

removing the stripes of sidewall spacers, leaving stripes of hardmask layer on the substrate.

11. The method of claim 10 further comprising:

etching the substrate, using the stripes of hardmask layer as an etch mask; and

removing the stripes of hardmask layer.

12. The method of claim 10 further comprising:

after depositing the hardmask layer, depositing a transfer layer on the hardmask layer; and

after etching away the DLC stripes, leaving stripes of sidewall spacer material on the transfer layer, etching away the transfer layer using the stripes of sidewall spacers as an etch mask, leaving stripes of sidewall spacers on stripes of transfer layer; and

then etching away the hardmask, using the stripes of sidewall spacers on the stripes of transfer layer as an etch mask.

13. The method of claim 10 wherein depositing the spacer layer by atomic layer deposition comprises using as gaseous precursors tetrakis(dimethylamido)titanium (TDMAT) and water vapor.

14. The method of claim 10 wherein depositing the spacer layer by atomic layer deposition comprises using as gaseous precursors tetrachloride (TiCl4) and water vapor.

15. The method of claim 10 wherein depositing the spacer layer by atomic layer deposition comprises using as gaseous precursors titanium butoxide (Ti(OBu)₄) and water vapor.

16. The method of claim 10 wherein the DLC stripes have a pitch in a direction parallel to the substrate and orthogonal to the DLC stripes of 2p₀ and the sidewall spacer stripes have a pitch in a direction parallel to the substrate and orthogonal to the sidewall spacer stripes of p₀.

17. The method of claim 10 wherein the DLC stripes have a width w, and wherein depositing the spacer layer comprises depositing the spacer layer to a thickness t, wherein t is approximately equal to p₀−

w.

18. The method of claim 10 wherein patterning the DLC layer into a plurality of stripes comprises patterning the DLC layer into a pattern selected from parallel generally straight stripes, generally radial stripes, and generally concentric circular stripes.