# US 12,765,290 B2 · Method of plasma etching > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,765,290 B2 - Document ID: US12765290B2 - Status: Granted - Kind: B2 - Application number: 18/375,009 - Filed: 2023-09-29 - Published: 2024-06-27 - Granted: 2026-10-13 - Earliest claimed: 2022-12-22 - Assignees: SPTS Technologies Limited - Applicants: SPTS Technologies Limited - Inventors: Binte Kazemi Samira - Web page: https://patentgrep.com/patent/US12765290B2 ## CPC - H10P 50/242: {of Group IV materials} - H01J 37/32449: {Gas control, e.g. control of the gas flow} - H10P 50/692: {characterised by their composition, e.g. multilayer masks or materials} - H10P 72/0421: {for drying etching} - H01J 2237/3341: Reactive etching - H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10 - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) ## Abstract An additive-containing aluminium nitride film is plasma etched. The additive-containing aluminium nitride film contains an additive element selected from scandium (Sc), yttrium (Y) or erbium (Er). A plasma is established within the chamber to plasma etch the additive-containing aluminium nitride film exposed within the trench. A ratio of the inert diluent gas flow rate to the sum of the BCl3 and Cl2 flow rates is in the range 0.45:1 to 0.75:1 and a ratio of the BCl3 flow rate to the Cl2 flow rate is in the range 0.75:1 to 1.25:1. ## Claims ### Claim 1 A method of plasma etching an additive-containing aluminium nitride film, the additive-containing aluminium nitride film containing an additive element selected from scandium (Sc), yttrium (Y) or erbium (Er), the method comprising the steps of: placing a workpiece upon a substrate support within a plasma chamber, the workpiece comprising a substrate having an additive-containing aluminium nitride film deposited thereon and a mask disposed upon the additive-containing aluminium nitride film which defines at least one trench; introducing BCl3 gas into the plasma chamber with a BCl3 flow rate in sccm; introducing Cl2 gas into the plasma chamber with a Cl2 flow rate in sccm; introducing an inert diluent gas into the plasma chamber with an inert diluent gas flow rate in sccm; and establishing a plasma within the plasma chamber to plasma etch the additive-containing aluminium nitride film exposed within the trench; wherein a ratio of the inert diluent gas flow rate to a sum of the BCl3 and Cl2 flow rates is in the range 0.45:1 to 0.75:1 and a ratio of the BCl3 flow rate to the Cl2 flow rate is in the range 0.75:1 to 1.25:1. ### Claim 2 (depends on 1) The method according to claim 1 in which the ratio of the inert diluent gas flow rate to the sum of the BCl3 and Cl2 flow rates is in the range 0.48:1 to 0.6:1. ### Claim 3 (depends on 1) The method according to claim 1 in which the ratio of the BCl3 flow rate to the Cl2 flow rate is in the range 0.9:1 to 1.1:1. ### Claim 4 (depends on 1) The method according to claim 1 in which the BCl3 flow rate and the Cl2 flow rate are each in the range 20 to 30 sccm. ### Claim 5 (depends on 1) The method according to claim 1 in which the inert diluent gas flow rate is in the range 20 to 30 sccm. ### Claim 6 (depends on 1) The method according to claim 1 in which the inert diluent gas is Argon. ### Claim 7 (depends on 1) The method according to claim 1, further comprising a first, main, plasma etching step to etch a majority of the additive-containing aluminium nitride film exposed within the trench, and followed by a second plasma etching step to etch the remaining additive-containing aluminium nitride film exposed within the trench. ### Claim 8 A method plasma etching an additive-containing aluminium nitride film, the additive-containing aluminium nitride film containing an additive element selected from scandium (Sc), yttrium (Y) or erbium (Er), the method comprising the steps of: placing a workpiece upon a substrate support within a plasma chamber, the workpiece comprising a substrate having a metal film disposed thereon, an additive-containing aluminium nitride film deposited on the metal film and a mask disposed upon the additive-containing aluminium nitride film which defines at least one trench; performing a first, main, plasma etching step in which BCl3 gas, Cl2 gas and an inert diluent gas are introduced into the plasma chamber and a plasma is established within the plasma chamber to plasma etch a majority of the additive-containing aluminium nitride film exposed within the trench; and performing a second plasma etching step in which BCl3 gas and an inert diluent gas are introduced into the plasma chamber but Cl2 gas is not introduced into the plasma chamber and a plasma is established within the plasma chamber to plasma etch the remaining additive-containing aluminium nitride film exposed within the trench thereby revealing the metal film. ### Claim 9 (depends on 8) The method according to claim 8 in which the BCl3 gas is introduced into the plasma chamber with a BCl3 flow rate in the range 50 to 100 sccm during the step of performing a second plasma etching step. ### Claim 10 (depends on 9) The method according to claim 9 in which the BCl3 gas is introduced into the plasma chamber with a BCl3 flow rate in the range 75 to 95 sccm during the step of performing a second plasma etching step. ### Claim 11 (depends on 8) The method according to claim 8 in which the inert diluent gas is introduced into the plasma chamber with an inert diluent gas flow rate in the range 10 to 20 sccm during the second plasma etching step. ### Claim 12 (depends on 8) The method according to claim 8 in which an RF bias signal having a power in the range 500 to 700 W is applied to the substrate support during the second plasma etching step. ### Claim 13 (depends on 8) The method according to claim 8 in which the inert diluent gas is Argon. ### Claim 14 (depends on 8) The method according to claim 8 in which the metal film is a molybdenum film. ### Claim 15 (depends on 8) The method according to claim 8 in which the mask is a photoresist mask. ### Claim 16 (depends on 8) The method according to claim 8, in which the plasma is an inductively coupled plasma (ICP). ### Claim 17 (depends on 8) The method according to claim 8 in which substrate is a semiconductor substrate. ### Claim 18 (depends on 8) The method according to claim 8 in which the additive-containing aluminium nitride film is an aluminium scandium nitride film defined by the formula AlxScyN, where x+y=1, and wherein the scandium content y is 0.35 or more.