# US 10,483,090 B2 · Restricted capacitor switching > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,483,090 B2 - Document ID: US10483090B2 - Status: Granted - Kind: B2 - Application number: 16/029,742 - Filed: 2018-07-09 - Published: 2019-01-10 - Granted: 2019-11-19 - Earliest claimed: 2017-07-10 - Assignees: Reno Technologies, Inc. - Applicants: Reno Technologies, Inc. - Inventors: Imran Ahmed Bhutta; Tomislav Lozic - Web page: https://patentgrep.com/patent/US10483090B2 ## CPC - H01J 37/32183: {Matching circuits} - H03H 7/40: Automatic matching of load impedance to source impedance - H03H 11/28: Impedance matching networks - H01J 2237/24564: Measurements of electric or magnetic variables, e.g. voltage, current, frequency - H01J 2237/332: Coating - H01J 2237/334: Etching - H10P 72/0421: {for drying etching} - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) - H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P) - H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10 ## Abstract In one embodiment, the present disclosure is directed to a method for matching an impedance. The method can include determining or receiving a reflection parameter value at an RF input or output; stopping the altering of a first capacitance and a second capacitance when the reflection parameter value is at or below a first reflection value; causing a limited altering of the first capacitance and the second capacitance to pursue an impedance match when the reflection parameter value is at or above a second reflection value and at or below the third reflection value; and causing an unlimited altering of the first capacitance and the second capacitance to pursue an impedance match when the reflection parameter value is at or above a third reflection value. ## Claims ### Claim 1 An impedance matching network, the network comprising: a radio frequency (RF) input configured to operably couple to an RF source; an RF output configured to operably couple to a plasma chamber; a first electronically variable capacitor (EVC) comprising discrete capacitors configured to be switched in and out to alter a first capacitance of the first EVC; a second EVC comprising discrete capacitors configured to be switched in and out to alter a second capacitance of the second EVC; and a control circuit operably coupled to the first and second EVCs, the control circuit configured to: determine or receive a reflection parameter value at the RF input or the RF output; stop the altering of the first capacitance and the second capacitance when the reflection parameter value is at or below a first reflection value; cause a limited altering of the first capacitance and the second capacitance to pursue an impedance match when the reflection parameter value is (a) at or above a second reflection value and (b) at or below the third reflection value, the limited altering allowing only a predetermined number of predetermined discrete capacitors to switch in or out; and cause an unlimited altering of the first capacitance and the second capacitance to pursue an impedance match when the reflection parameter value is at or above a third reflection value, the unlimited altering allowing any discrete capacitor of the first or second EVC to switch in or out. ### Claim 2 (depends on 1) The matching network of claim 1 wherein the reflection parameter value is a load impedance at the RF output. ### Claim 3 (depends on 1) The matching network of claim 1 wherein the control circuit is further configured to continuously monitor the reflection parameter value. ### Claim 4 (depends on 1) The matching network of claim 1 wherein the discrete capacitors of each of the first EVC and the second EVC comprise coarse and fine capacitors, wherein the coarse capacitors have a capacitance at least twice as large as the capacitance of the fine capacitors, and wherein the predetermined discrete capacitors are fine capacitors. ### Claim 5 (depends on 4) The matching network of claim 4 wherein the predetermined number is two. ### Claim 6 (depends on 1) The matching network of claim 1 wherein the reflection parameter value is a reflection coefficient value representing a ratio of an amplitude of a reflected wave to an incident wave at the RF input or the RF output. ### Claim 7 (depends on 6) The matching network of claim 6 wherein the reflection coefficient value is determined based on a sensor signal from a sensor at the RF input. ### Claim 8 (depends on 1) The matching network of claim 1 wherein the control circuit is further configured to, before altering the first capacitance or the second capacitance, determine a positioning for the discrete capacitors to achieve an impedance match, the limited altering preventing the determined positioning of the discrete capacitors from being fully carried out. ### Claim 9 (depends on 8) The matching network of claim 8 wherein the unlimited altering allows the determined positioning of the discrete capacitors to be fully carried out. ### Claim 10 A semiconductor processing tool comprising: a plasma chamber configured to deposit a material onto a substrate or etch a material from the substrate; and an impedance matching network operably coupled to the plasma chamber, the matching network comprising: a radio frequency (RF) input configured to operably couple to an RF source; an RF output configured to operably couple to the plasma chamber; a first electronically variable capacitor (EVC) comprising discrete capacitors configured to be switched in and out to alter a first capacitance of the first EVC; a second EVC comprising discrete capacitors configured to be switched in and out to alter a second capacitance of the second EVC; and a control circuit operably coupled to the first and second EVCs, the control circuit configured to: determine or receive a reflection parameter value at the RF input or the RF output; stop the altering of the first capacitance and the second capacitance when the reflection parameter value is at or below a first reflection value; cause a limited altering of the first capacitance and the second capacitance to pursue an impedance match when the reflection parameter value is (a) at or above a second reflection value and (b) at or below the third reflection value, the limited altering allowing only a predetermined number of predetermined discrete capacitors to switch in or out; and cause an unlimited altering of the first capacitance and the second capacitance to pursue an impedance match when the reflection parameter value is at or above a third reflection value, the unlimited altering allowing any discrete capacitor of the first or second EVC to switch in or out. ### Claim 11 (depends on 10) The processing tool of claim 10 wherein the discrete capacitors of each of the first EVC and the second EVC comprise coarse and fine capacitors, wherein the coarse capacitors have a capacitance at least twice as large as the capacitance of the fine capacitors, and wherein the predetermined discrete capacitors are fine capacitors. ### Claim 12 (depends on 10) The processing tool of claim 10 wherein the reflection parameter value is a reflection coefficient value representing a ratio of an amplitude of a reflected wave to an incident wave at the RF input or the RF output. ### Claim 13 (depends on 10) The processing tool of claim 10 wherein the reflection parameter value is a load impedance at the RF output. ### Claim 14 (depends on 10) The processing tool of claim 10 wherein the control circuit is further configured to, before altering the first capacitance or the second capacitance, determine a positioning for the discrete capacitors to achieve an impedance match, the limited altering preventing the determined positioning of the discrete capacitors from being fully carried out. ### Claim 15 A method of matching an impedance comprising: operably coupling a radio frequency (RF) input of a matching network to an RF source; operably coupling an RF output of the matching network to a plasma chamber, the plasma chamber comprising (a) a first electronically variable capacitor (EVC) comprising discrete capacitors configured to be switched in and out to alter a first capacitance of the first EVC, and (b) a second EVC comprising discrete capacitors configured to be switched in and out to alter a second capacitance of the second EVC; and determining or receiving a reflection parameter value at the RF input or the RF output; stopping the altering of the first capacitance and the second capacitance when the reflection parameter value is at or below a first reflection value; causing a limited altering of the first capacitance and the second capacitance to pursue an impedance match when the reflection parameter value is (a) at or above a second reflection value and (b) at or below the third reflection value, the limited altering allowing only a predetermined number of predetermined discrete capacitors to switch in or out; and causing an unlimited altering of the first capacitance and the second capacitance to pursue an impedance match when the reflection parameter value is at or above a third reflection value, the unlimited altering allowing any discrete capacitor of the first or second EVC to switch in or out. ### Claim 16 (depends on 15) The method of claim 15 wherein the discrete capacitors of each of the first EVC and the second EVC comprise coarse and fine capacitors, wherein the coarse capacitors have a capacitance at least twice as large as the capacitance of the fine capacitors, and wherein the predetermined discrete capacitors are fine capacitors. ### Claim 17 (depends on 15) The method of claim 15 wherein the reflection parameter value is a reflection coefficient value representing a ratio of an amplitude of a reflected wave to an incident wave at the RF input or the RF output. ### Claim 18 (depends on 15) The method of claim 15 wherein the reflection parameter value is a load impedance at the RF output. ### Claim 19 (depends on 15) The method of claim 15 further comprising, before altering the first capacitance or the second capacitance, determining a positioning for the discrete capacitors to achieve an impedance match, the limited altering preventing the determined positioning of the discrete capacitors from being fully carried out. ### Claim 20 A method of manufacturing a semiconductor, the method comprising: placing a substrate in a plasma chamber configured to deposit a material layer onto the substrate or etch a material layer from the substrate; and coupling an impedance matching circuit between a radio frequency (RF) source and the plasma chamber, the impedance matching circuit comprising: a radio frequency (RF) input configured to operably couple to an RF source; an RF output configured to operably couple to a plasma chamber; a first electronically variable capacitor (EVC) comprising discrete capacitors configured to be switched in and out to alter a first capacitance of the first EVC; a second EVC comprising discrete capacitors configured to be switched in and out to alter a second capacitance of the second EVC; and a control circuit operably coupled to the first and second EVCs, the control circuit configured to: determine or receive a reflection parameter value at the RF input or the RF output; stop the altering of the first capacitance and the second capacitance when the reflection parameter value is at or below a first reflection value; cause a limited altering of the first capacitance and the second capacitance to pursue an impedance match when the reflection parameter value is (a) at or above a second reflection value and (b) at or below the third reflection value, the limited altering allowing only a predetermined number of predetermined discrete capacitors to switch in or out; and cause an unlimited altering of the first capacitance and the second capacitance to pursue an impedance match when the reflection parameter value is at or above a third reflection value, the unlimited altering allowing any discrete capacitor of the first or second EVC to switch in or out.