MULTIPLE DEPOSITION FOR INTEGRATION OF SPACERS IN PITCH MULTIPLICATION PROCESS

• US 20080149593A1
• Filed: 03/04/2008
• Published: 06/26/2008
• Est. Priority Date: 08/25/2005
• Status: Active Grant

• Current Assignee: Round Rock Research LLC
• Original Assignee: Micron Technology, Inc.
• Inventors: Bai, Jingyi, Sandhu, Gurtej S., Meng, Shuang
• Granted Patent: US 8,123,968 B2
• Time in Patent Office: Days
• US Class Current: 216/47
• CPC Class Codes: H01L 21/02164 the material being a silicon oxide, e.g. SiO2
• CPC Class Codes: H01L 21/022 the layer being a laminate, i.e. composed of sublayers, e.g. stacks of alternating high-k metal oxides adhesion layers or buffer layers H01L21/02304, H01L21/02362
• CPC Class Codes: H01L 21/02271 deposition by decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition H01L21/02266 takes precedence
• 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 21/31612 on a silicon body

Abstract

Pitch multiplication is performed using a two step process to deposit spacer material on mandrels. The precursors of the first step react minimally with the mandrels, forming a barrier layer against chemical reactions for the deposition process of the second step, which uses precursors more reactive with the mandrels. Where the mandrels are formed of amorphous carbon and the spacer material is silicon oxide, the silicon oxide is first deposited by a plasma enhanced deposition process and then by a thermal chemical vapor deposition process. Oxygen gas and plasma-enhanced tetraethylorthosilicate (TEOS) are used as reactants in the plasma enhanced process, while ozone and TEOS are used as reactants in the thermal chemical vapor deposition process. The oxygen gas is less reactive with the amorphous carbon than ozone, thereby minimizing deformation of the mandrels caused by oxidation of the amorphous carbon.

Claims

1. A process for patterning a substrate, comprising:

providing a plurality of laterally-spaced mandrels over the substrate;

blanket depositing a first layer of silicon oxide on the mandrels by plasma-enhanced chemical vapor deposition, the first layer disposed on sidewalls of the mandrels;

subsequently blanket depositing a second layer of silicon oxide on the first layer, the second layer extending along the sidewalls of the mandrels;

anisotropically etching the first and second layers of silicon oxide;

selectively removing the mandrels to form a pattern of free-standing spacers; and

transferring the pattern to the substrate.

2. The process of claim 1, wherein precursors for blanket depositing the first layer comprise O₂ and TEOS.

3. The process of claim 2, wherein precursors for blanket depositing the second layer comprise O₃ and TEOS.

4. The process of claim 2, wherein blanket depositing the first layer comprises generating plasma excited species from the O₂.

5. The process of claim 1, wherein the first layer has a higher conformality than the second layer.

6. The process of claim 1, wherein the first and second layers have different ratios of oxygen to silicon.

7. The process of claim 1, wherein anisotropically etching the first and second layers comprises performing different etches for each of the first and second layers.

8. The process of claim 1, wherein providing a plurality of mandrels comprises:

photolithographically defining a pattern in a photoresist layer; and

transferring the pattern into an amorphous carbon layer, wherein the mandrels comprise amorphous carbon.

9. The process of claim 1, wherein transferring the pattern to the substrate defines conductive lines in the substrate.

10. A method for patterning a substrate, comprising:

providing a plurality of mandrels over the substrate;

depositing a chemical reaction barrier on sidewalls of the mandrels;

depositing, along sidewalls of the mandrels, a layer of spacer material on the chemical reaction barrier; and

preferentially removing the mandrels relative to the chemical reaction barrier and relative to the spacer material to form a pattern of free-standing spacers comprising the spacer material and material of the chemical reaction barrier.

11. The method of claim 10, wherein the first layer is less porous than the second layer.

12. The method of claim 10, wherein depositing the chemical reaction barrier comprises performing an atomic layer deposition, and wherein depositing the layer of spacer material comprises performing a thermal chemical vapor deposition.

13. The method of claim 12, wherein the chemical reaction barrier and the spacer material comprise silicon oxide.

14. The method of claim 10, further comprising processing the substrate through openings in the pattern of free-standing spacers.

15. The method of claim 14, wherein processing the substrate comprises selectively etching the substrate relative to the spacers.

16. The method of claim 14, wherein processing the substrate comprises:

transferring the pattern to a hard mask layer underlying the spacers; and

etching the substrate through openings in the hard mask layer.

17. The method of claim 14, wherein processing the substrate defines features of a memory array of a memory device.

18. A process for patterning a substrate, comprising:

providing a plurality of mandrels over the substrate;

blanket depositing a plurality of materials of different densities over the mandrels, the plurality of materials deposited along sidewalls of the mandrels;

etching the deposited plurality of materials to form spacers along sidewalls of the mandrels;

removing the mandrels;

transferring a pattern defined by the spacers to the substrate; and

removing the spacers.

19. The process of claim 18, wherein each of the materials is the same material, wherein a first layer of the deposited material has a higher density than a later deposited layer of the material.

20. The process of claim 18, wherein blanket depositing comprises performing a plurality of different deposition processes.

21. The process of claim 20, wherein each process comprises using a different set of reactants.

22. The process of claim 20, wherein the processes are selected from the group consisting of plasma-enhanced chemical vapor deposition, thermal chemical vapor deposition and atomic layer deposition.

23. The process of claim 18, wherein transferring the pattern comprises performing a plurality of etches to etch through a plurality of different materials.

24. The process of claim 18, wherein transferring the pattern comprises:

etching the pattern into an underlying masking layer, wherein the spacers are removed while etching the pattern into the underlying masking layer; and

etching the substrate through the masking layer.

25. The process of claim 18, wherein the mandrels extend in spaced, generally parallel relation to one another.