# US 11,994,542 B2 · RF signal parameter measurement in an integrated circuit fabrication chamber > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,994,542 B2 - Document ID: US11994542B2 - Status: Granted - Kind: B2 - Application number: 16/832,961 - Filed: 2020-03-27 - Published: 2021-09-30 - Granted: 2024-05-28 - Earliest claimed: 2020-03-27 - Assignees: Lam Research Corporation - Applicants: Lam Research Corporation - Inventors: Sunil Kapoor; David French - Web page: https://patentgrep.com/patent/US11994542B2 ## CPC - G01R 19/2509: {Details concerning sampling, digitizing or waveform capturing} - G01R 15/16: using capacitive devices - G01R 15/18: using inductive devices, e.g. transformers - H01J 37/32183: {Matching circuits} - H01J 37/32899: {Multiple chambers, e.g. cluster tools} - H01J 37/32926: {Software, data control or modelling} - H01J 37/32935: {Monitoring and controlling tubes by information coming from the object and/or discharge} - H10P 72/0452: {characterised by the layout of the process chambers} - H10P 72/0604: {Process monitoring, e.g. flow or thickness monitoring} - H01J 2237/24495: Signal processing, e.g. mixing of two or more signals - H01J 2237/24564: Measurements of electric or magnetic variables, e.g. voltage, current, frequency - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) - H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10 ## Abstract An apparatus to estimate parameters of a radio frequency (RF) signal may include a voltage sensor configured to provide an indication of a voltage of the RF signal as well as a current sensor configured to provide an indication of current conducted by the RF signal. The apparatus may additionally include an analog-to-digital conversion module coupled to an output port of the voltage sensor and the current sensor, wherein the analog-to-digital converter is configured to provide digital representations of an instantaneous voltage and an instantaneous current of the RF signal. The apparatus may additionally include one or more processors configured to transform the digital representations of the instantaneous voltage and current into frequency domain representations of a complex voltage and complex current. ## Claims ### Claim 1 An apparatus to estimate parameters of a radio frequency (RF) signal coupled to an integrated circuit fabrication chamber, comprising: a voltage sensor configured to provide an indication of a voltage of the RF signal; a current sensor configured to provide an indication of a current conducted by the RF signal; an analog-to-digital conversion module coupled to an output port of the voltage sensor and to an output port of the current sensor, the analog-to-digital converter configured to provide digital representations of an instantaneous voltage and an instantaneous current of the RF signal; and one or more processors configured to transform the digital representations of the instantaneous voltage and the digital representations of the instantaneous current into frequency domain representations of a complex voltage corresponding to the RF signal voltage and into frequency domain representations of a complex current corresponding to the RF signal current, the one or more processors additionally configured to combine frequency domain representations of the complex voltage and the complex current to form root mean square (RMS) voltage and RMS current, wherein the frequency domain representations of the complex voltage and the frequency domain representations of the complex current each include a plurality of samples. ### Claim 2 (depends on 1) The apparatus of claim 1, wherein at least one of the one or more processors is configured to perform a Fast Fourier Transform (FFT) of the digital representation of the instantaneous voltage of the RF signal and of the instantaneous current of the RF signal. ### Claim 3 (depends on 1) The apparatus of claim 1, wherein the voltage sensor comprises a capacitive voltage sensor. ### Claim 4 (depends on 1) The apparatus of claim 1, wherein the current sensor comprises an inductive current transformer. ### Claim 5 (depends on 1) The apparatus of claim 1, wherein the analog-to-digital conversion module is configured to apply a successive-approximation technique. ### Claim 6 (depends on 1) The apparatus of claim 1, wherein the RF signal is provided by an RF power generator that provides at least 2 frequency components. ### Claim 7 (depends on 6) The apparatus of claim 6, wherein the at least 2 frequency components comprise a first frequency of about 400 kHz and a second frequency of about 13.56 MHz. ### Claim 8 (depends on 1) The apparatus of claim 1, wherein the one or more processors are additionally configured to apply one or more calibration coefficients to the frequency domain representations of the complex voltage and to apply one or more calibration coefficients to the frequency domain representations of the complex current, wherein the one or more calibration coefficients represent frequency-dependent deviations from ideal scattering parameters. ### Claim 9 (depends on 1) The apparatus of claim 1, wherein the apparatus is exclusive of a voltage divider. ### Claim 10 (depends on 1) The apparatus of claim 1, wherein the apparatus is exclusive of a peak detector. ### Claim 11 (depends on 1) The apparatus of claim 1, wherein the apparatus is exclusive of a buffer amplifier. ### Claim 12 (depends on 1) The apparatus of claim 1, wherein the frequency domain representations of the complex voltage and the complex current are combined to obtain actual power delivered to a process station. ### Claim 13 (depends on 12) The apparatus of claim 12, wherein the frequency domain representations of the complex voltage and the complex current are combined to obtain power factor at the process station. ### Claim 14 An apparatus adapted to estimate radio frequency (RF) power coupled to a station of an integrated circuit fabrication chamber, comprising: a voltage sensor configured to provide an indication of a voltage of the RF signal; a current sensor configured to provide an indication of the current conducted by the RF signal; an analog-to-digital conversion module coupled to an output port of the voltage sensor and to an output port of the current sensor, the analog-to-digital converter configured to provide digital representations of an instantaneous voltage and an instantaneous current of the RF signal; and one or more processors configured to: obtain the digital representations of the instantaneous voltage of the RF signal and the digital representations of the instantaneous current conducted by the RF signal; transform the obtained digital representations of the instantaneous voltage of the RF signal and the instantaneous current of the RF signal into a frequency domain representation of a complex voltage corresponding to the voltage of the RF signal and into a frequency domain representation of a complex current corresponding to the current conducted by the RF signal; and combine the complex voltage of the RF signal and the complex current of the RF signal to form root mean square (RMS) voltage and RMS current, wherein the frequency domain representation of the complex voltage and the frequency domain representation of the complex current each include a plurality of samples. ### Claim 15 (depends on 14) The apparatus of claim 14, wherein the one or more processors is configured to transform the obtained digital representations of the instantaneous voltage of the RF signal and the instantaneous current conducted by the RF signal utilizing a Fast Fourier Transform. ### Claim 16 (depends on 14) The apparatus of claim 14 wherein the one or more processors is additionally configured to apply one or more calibration coefficients to the complex voltage of the RF signal and the complex current conducted by the RF signal, wherein the one or more calibration coefficients represent frequency-dependent deviations from ideal scattering parameters. ### Claim 17 (depends on 14) The apparatus of claim 14, wherein the one or more processors is additionally configured to utilize the complex voltage of the RF signal and the complex current of the RF signal to obtain power delivered to a station of the integrated circuit fabrication chamber. ### Claim 18 (depends on 17) The apparatus of claim 17, wherein the one or more processors is additionally configured to utilize the complex voltage of the RF signal and the complex current of the RF signal to obtain a ratio of power delivered to forward power at the station of the integrated circuit fabrication chamber. ### Claim 19 (depends on 14) The apparatus of claim 14, wherein the apparatus is exclusive of a buffer amplifier.