METHOD OF ANISOTROPIC EXTRACTION OF SILICON NITRIDE MANDREL FOR FABRICATION OF SELF-ALIGNED BLOCK STRUCTURES

• US 20180277386A1
• Filed: 02/23/2018
• Published: 09/27/2018
• Est. Priority Date: 02/23/2017
• Status: Active Grant

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Sherpa, Sonam D., Ranjan, Alok
• Granted Patent: US 10,446,405 B2
• Time in Patent Office: Days
• 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 21/3065 Plasma etching; Reactive-ion etching
• 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 21/311 Etching the insulating layers by chemical or physical means H01L21/31058 takes precedence
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/31144 using masks
• CPC Class Codes: H01L 21/3213 Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer
• CPC Class Codes: H01L 21/32137 of silicon-containing layers
• CPC Class Codes: H01L 21/768 Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics

Abstract

A method of preparing a self-aligned block (SAB) structure is described. The method includes providing a substrate having raised features defined by a first material containing silicon nitride and a second material containing silicon oxide formed on side walls of the first material, and a third material containing an organic material covering some of the raised features and exposing some raised features according to a block pattern formed in the third material. The method further includes forming a first chemical mixture by plasma-excitation of a first process gas containing H and optionally a noble gas, and exposing the first material on the substrate to the first chemical mixture. Thereafter, the method includes forming a second chemical mixture by plasma-excitation of a second process gas containing N, F, O, and optionally a noble element, and exposing the first material on the substrate to the second plasma-excited process gas to selectively etch the first material relative to the second and third material.

Claims

1. A method of preparing a self-aligned block (SAB) structure, comprising:

providing a substrate having raised features defined by a first material containing silicon nitride and a second material containing silicon oxide formed on side walls of the first material, and a third material containing an organic material covering some of the raised features and exposing some raised features according to a block pattern formed in the third material;

forming a first chemical mixture by plasma-excitation of a first process gas containing H and optionally a noble gas;

exposing the first, second, and third materials on the substrate to the first chemical mixture;

thereafter, forming a second chemical mixture by plasma-excitation of a second process gas containing S, F, and optionally a noble element; and

exposing the first, second, and third materials on the substrate to the second plasma-excited process gas to selectively etch the first material relative to the second and third materials.

2. The method of claim 1, wherein the first process gas contains H₂.

3. The method of claim 1, wherein the first process gas consists of H₂.

4. The method of claim 1, wherein the first process gas consists of H₂ and Ar.

5. The method of claim 1, wherein the second process gas contains SF₆ and Ar.

6. The method of claim 1, wherein the second process gas consists of SF₆ and Ar.

7. The method of claim 1, wherein the first chemical mixture contains hydrogen ions.

8. The method of claim 1, wherein the second chemical mixture contains substantially charge-neutral species.

9. The method of claim 1, wherein the second material is selected from the group consisting of SiO₂ and organic materials.

10. The method of claim 1, wherein the first material includes raised features on the substrate, the second material forms sidewall spacers on the vertical portions of the raised features, and wherein the exposing removes the raised features of the first material but not the sidewall spacers.

11. The method of claim 1, wherein the plasma excitation of the first process gas or the second process gas includes generating plasma using a capacitively coupled plasma source containing an upper plate electrode, and a lower plate electrode supporting the substrate.

12. The method of claim 1, wherein the plasma excitation of the first process gas or the second process gas includes generating plasma using an inductively coupled plasma source containing an inductive element, and a lower plate electrode supporting the substrate.

13. The method of claim 1, wherein the plasma excitation of the first process gas or the second process gas includes generating plasma using a remote plasma source that creates a high radical to ion flux ratio.

14. The method of claim 1, further comprising:

repeating the steps of forming the first chemical mixture, exposing the first material to the first chemical mixture, forming the second chemical mixture, and exposing the first material to the second chemical mixture to incrementally remove additional portions of the first material.

15. The method of claim 1, wherein the first material is removed at an etch selectivity of greater than 100-to-1 relative to the second and third materials.

16. The method of claim 1, wherein the raised feature is a mandrel in a self-aligned multi-patterning process.

17. The method of claim 16, wherein an aspect ratio of the raised feature exceeds 10.

18. A method of preparing a self-aligned block (SAB) structure, comprising:

providing a substrate having raised features defined by a first material containing silicon nitride and a second material containing silicon oxide formed on side walls of the first material, and a third material containing an organic material covering some of the raised features and exposing some raised features according to a block pattern formed in the third material;

forming a first chemical mixture by plasma-excitation of a first process gas containing H and optionally a noble gas;

exposing the first, second, and third materials on the substrate to the first chemical mixture;

thereafter, forming a second chemical mixture by plasma-excitation of a second process gas containing a high fluorine content molecule, and optionally a noble element, wherein the ratio of fluorine to other atomic elements of the high fluorine content molecule exceeds unity; and

exposing the first, second, and third materials on the substrate to the second plasma-excited process gas to selectively etch the first material relative to the second and third materials.