# US 10,312,102 B2 · Method of quasi-atomic layer etching of silicon nitride > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,312,102 B2 - Document ID: US10312102B2 - Status: Granted - Kind: B2 - Application number: 15/686,546 - Filed: 2017-08-25 - Published: 2018-03-01 - Granted: 2019-06-04 - Earliest claimed: 2016-08-29 - Assignees: Tokyo Electron Limited - Applicants: Tokyo Electron Limited - Inventors: Sonam D. Sherpa; Alok Ranjan - Web page: https://patentgrep.com/patent/US10312102B2 ## CPC - H10P 50/242: {of Group IV materials} - C23C 16/0245: {by etching with a plasma} - H10P 76/4085: {characterised by the processes involved to create the masks} - C01B 21/068: with silicon - H10P 50/283: {by chemical means} - H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10 - C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04) - C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C} ## Abstract A method of etching is described. The method includes providing a substrate having a first material containing silicon nitride and a second material that is different from the first material, 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 material. ## Claims ### Claim 1 A method of etching, comprising: providing a substrate in a plasma processing apparatus, wherein the plasma processing apparatus includes a first power source and a second power source, and the second power source operates at a higher frequency than the first power source, and wherein the substrate includes a first material containing silicon nitride and a second material that is different from the first material; forming a first chemical mixture in the plasma processing apparatus by plasma-excitation of a first process gas consisting essentially of hydrogen and optionally a noble gas; exposing the first material on the substrate to the first chemical mixture in the plasma processing apparatus; after the exposing the first material to the first chemical mixture, forming a second chemical mixture in the plasma processing apparatus by plasma-excitation of a second process gas containing N, F, O, and optionally a noble element; exposing the first material on the substrate to the second plasma-excited process gas in the plasma processing apparatus to selectively etch the first material relative to the second material; and wherein during the forming of the first chemical mixture and exposing the first material to the first chemical mixture, the second power source is off. ### Claim 2 (depends on 1) The method of claim 1, wherein the first process gas consists of H2. ### Claim 3 (depends on 1) The method of claim 1, wherein the first process gas consists of H2 and Ar. ### Claim 4 (depends on 1) The method of claim 1, wherein the second process gas contains NF3, O2, and Ar. ### Claim 5 (depends on 1) The method of claim 1, wherein the second process gas consists of NF3, O2, and Ar. ### Claim 6 (depends on 1) The method of claim 1, wherein the first chemical mixture contains hydrogen ions, and wherein the second chemical mixture contains substantially charge-neutral species. ### Claim 7 (depends on 1) The method of claim 1, wherein the second material is selected from the group consisting of SiO2 and organic materials. ### Claim 8 (depends on 1) The method of claim 1, wherein the first material includes raised features on the substrate, the second material forms sidewall spacers on vertical portions of the raised features, with the sidewall spacers of the second material adjacent to and surrounding the raised features formed of the first material, and wherein the exposing to the second plasma-excited processing gas removes the raised features of the first material but not the sidewall spacers. ### Claim 9 (depends on 1) 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. ### Claim 10 (depends on 1) 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. ### Claim 11 (depends on 1) 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. ### Claim 12 (depends on 1) 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. ### Claim 13 (depends on 1) 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 material. ### Claim 14 (depends on 1) The method of claim 1, wherein the first material is part of a spacer layer conformally applied over a gate structure. ### Claim 15 (depends on 1) The method of claim 1, wherein the first material is part of a spacer layer conformally applied over a mandrel in a self-aligned multi-patterning (SAMP) process. ### Claim 16 (depends on 1) The method of claim 1, wherein the first material is a mandrel in a self-aligned multi-patterning (SAMP) process. ### Claim 17 (depends on 1) The method of claim 1, wherein the first material is a liner on a raised feature or a liner in a recessed feature. ### Claim 18 (depends on 1) The method of claim 1, wherein during the exposing of the first material on the substrate to the first chemical mixture, the silicon nitride material becomes hydrogenated at a surface region and a sub-surface region of the silicon nitride material; and wherein during the exposing of the first material on the substrate to the second plasma-excited process gas, an etch rate of the silicon nitride material initially is increasing during etching of the surface region and a first portion of the sub-surface region, and thereafter the etch rate of the silicon nitride material is decreasing during etching of a second portion of the sub-surface region. ### Claim 19 (depends on 1) The method of claim 1, wherein the first material consists essentially of SixNy, where x and y are integers, and the second material includes silicon, titanium, or an organic material; wherein during the exposing the first material to the first chemical mixture the first and second materials are not etched, and at least the first material is hydrogenated in surface and sub-surface regions of the first material, and wherein after the exposing the first material to the first chemical mixture the sub-surface regions include a first portion having a hydrogen concentration greater than that at the surface and a second portion having a hydrogen concentration lower than that at the surface; and wherein the exposing the first material to the first chemical mixture is performed at a pressure lower than a pressure of the exposing the first material to the second plasma-excited process gas.