Method of etching substrate

• US 10,643,858 B2
• Filed: 08/08/2018
• Issued: 05/05/2020
• Est. Priority Date: 10/11/2017
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Lee, Eunwoo, Oh, Sangrok, Sung, Jungmo, Sun, Jongwoo
• Primary Examiner(s): Munoz, Andres
• Application Number:
  US16/058,981
• Publication Number:
  US 20190109010A1
• Time in Patent Office: 636 Days
• Field of Search: None
• CPC Class Codes: H01L 21/0274 Photolithographic processes
• 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 21/3081 characterised by their composition, e.g. multilayer masks, materials
• CPC Class Codes: H01L 21/3086 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 21/3105 After-treatment

Abstract

A method of forming patterns of a semiconductor device includes forming a photoresist pattern, which contains a first carbon compound, on a substrate, reforming a top surface of the photoresist pattern to form an upper mask layer which contains a second carbon compound, different from the first carbon compound, on the photoresist pattern, and etching a portion of the substrate using the upper mask layer and the photoresist pattern as an etch mask.

Claims

1. A pattern forming method, comprising:

forming a photoresist pattern on a substrate, the photoresist pattern containing a first carbon compound;

a reforming process of forming an upper mask layer on a top surface of the photoresist pattern, the upper mask layer containing a second carbon compound different in kind from the first carbon compound; and

etching a portion of the substrate using the upper mask layer and the photoresist pattern as an etch mask,

wherein the second carbon compound comprises a carbon-nitrogen compound.

2. The method of claim 1, wherein the first carbon compound comprises a polyacetal resin.

3. The method of claim 1, wherein the second carbon compound comprises cyanoethynyl (C₃N).

4. The method of claim 1, wherein the reforming process comprises:

providing the substrate in a chamber;

introducing a nitrogen gas and a methane gas into an upper portion of the chamber over the substrate; and

providing an upper power to the upper portion of the chamber, into which the nitrogen gas and the methane gas are introduced, to induce plasma in the chamber and to deposit radicals in the plasma on the photoresist pattern.

5. The method of claim 4, wherein, when the upper power is provided, the nitrogen gas and the methane gas are provided at a flow rate ratio ranging from 0.6:

1 to 1;

2.

6. The method of claim 4, wherein the substrate is provided in a lower portion of the chamber below the upper portion, and the reforming process further comprises:

cutting off the upper power; and

providing a lower power to the lower portion of the chamber to re-induce the plasma and to remove a portion of the radicals using ions in the plasma.

7. The method of claim 6, wherein, when the lower power is provided, the nitrogen gas and the methane gas are introduced into the upper portion of the chamber at a flow rate ratio of 10:

1.

8. The method of claim 6, wherein each of the upper power and the lower power is applied in the form of a continuous wave, and frequencies of the continuous waves of the upper and lower powers are equal to each other.

9. The method of claim 1, further comprising forming a hard mask layer on the substrate before the photoresist pattern is formed so that the hard mask layer is interposed between the substrate and the photoresist pattern,

wherein the hard mask layer comprises silicon oxynitride.

10. A pattern forming method, comprising:

forming a hard mask layer comprising silicon oxynitride, on a substrate;

forming a photoresist pattern that is photo-sensitive to extreme ultraviolet (EUV) light on the hard mask layer;

a reforming process of forming an upper mask layer on a top surface of the photoresist pattern; and

etching the hard mask layer and a portion of the substrate using the photoresist pattern and the upper mask layer as an etch mask,

wherein the reforming process comprises;

supplying a nitrogen gas and a methane gas into a region over the substrate at a flow rate ratio of 10;

1;

applying an upper power to the region over the substrate to induce plasma and to deposit radicals in the plasma onto the upper mask layer; and

applying a lower power to a region below the substrate to re-induce the plasma and to remove a portion of the upper mask layer using ions in the plasma.

11. The method of claim 10, wherein the reforming process further comprises cutting off the upper power, before the applying of the lower power.

12. The method of claim 10, wherein the lower power is higher than the upper power.

13. The method of claim 12, wherein the upper power is applied at a positive voltage, and

the lower power is applied at a negative voltage.

14. The method of claim 10, wherein each of the upper power and the lower power is applied in the form of a continuous wave.

15. A method of etching a substrate, comprising:

forming a photoresist pattern on a substrate;

supplying a nitrogen gas and a methane gas into a region over the photoresist pattern at a first flow rate ratio;

applying an upper power to the nitrogen gas and the methane gas to induce plasma and to deposit radicals in the plasma on the photoresist pattern;

cutting off the upper power;

supplying the nitrogen gas and the methane gas at a second flow rate ratio, in which a fraction of the nitrogen gas is higher than that in the first flow rate ratio; and

applying a lower power to the nitrogen gas and the methane gas to re-induce the plasma and to remove a portion of the deposited radicals using ions in the plasma.

16. The method of claim 15, wherein the first flow rate ratio of the nitrogen gas to the methane gas ranges from 0.6:

1 to 1;

2.

17. The method of claim 15, wherein the second flow rate ratio of the nitrogen gas to the methane gas is 10:

1.

18. The method of claim 15, wherein the radicals contain a carbon-hydrogen compound.

19. The method of claim 15, wherein the radicals contain cyanoethynyl (C₃N).