# US 7,743,670 B2 · Method and apparatus for gas flow measurement

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- Number: US 7,743,670 B2
- Document ID: US7743670B2
- Status: Granted
- Kind: B2
- Application number: 11/833,623
- Filed: 2007-08-03
- Published: 2008-02-14
- Granted: 2010-06-29
- Earliest claimed: 2006-08-14
- Assignees: Applied Materials, Inc.
- Inventors: Jared Ahmed Lee; Ezra Robert Gold; Chunlei Zhang; James Patrick Cruse; Richard Charles Fovell
- Web page: https://patentgrep.com/patent/US7743670B2

## CPC

- G01F 25/15: {specially adapted for gas meters (G01F25/11 - G01F25/14, G01F25/17 take precedence)}
- G01F 25/17: using calibrated reservoirs
- Y10T 137/0368: By speed of fluid
- Y10T 137/7761: Electrically actuated valve
- G01F: MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A method and apparatus for measuring gas flow are provided. In one embodiment, a calibration circuit for gas control may be utilized to verify and/or calibrate gas flows utilized for backside cooling, process gas delivery, purge gas delivery, cleaning agent delivery, carrier gases delivery and remediation gas delivery, among others.

## Claims

### Claim 1

Apparatus for delivering gas in a processing system having a processing chamber, comprising:
a gas source;
a diverter valve having an inlet, a first outlet and a second outlet, the second outlet coupled to the processing chamber;
a regulating device fluidly coupled between the gas source and the inlet of the diverter valve;
an orifice fluidly coupled to the first outlet of the diverter valve, the orifice having substantially the same flow resistance as the processing chamber; and
a sensing circuit configured to receive flow passing through the orifice, wherein the sensing circuit comprises:
a sensor;
a by-pass loop around the sensor;
a tank; and
a valve diverting the flow from the orifice between the tank and the by-pass loop.

### Claim 2 (depends on 1)

The apparatus of claim 1, wherein the regulating device further comprises at least one of a vapor delivery module, a flow divider, a pressure controller, a regulator or a mass flow controller.

### Claim 3 (depends on 1)

The apparatus for claim 1, wherein the tank has a calibrated volume.

### Claim 4 (depends on 3)

The apparatus for claim 3, wherein the sensing circuit further comprises:
a vibrating member disposed in the calibrated volume.

### Claim 5 (depends on 3)

The apparatus for claim 3, wherein the sensor is configured to detect at least one of electrical or magnetic characteristics of gases disposed in the calibrated volume.

### Claim 6 (depends on 1)

The apparatus for claim 1, wherein the tank is supported by a cantilever.

### Claim 7 (depends on 1)

The apparatus for claim 1, wherein the sensing circuit has a calibrated volume for receiving the gas flow, and the sensor arranged to measure at least one property and/or attribute of the gas in the calibrated volume from which a flow rate and/or pressure of the gas entering the sensing circuit may be resolved.

### Claim 8 (depends on 1)

The apparatus for claim 1, wherein the sensing circuit further has a non-calibrated volume for receiving the gas flow, and the sensor arranged to measure changes in at least one property and/or attribute of the gas in the non-calibrated volume from which a flow rate and/or pressure of the gas entering the sensing circuit may be resolved.

### Claim 9

A method for calibrating a flow control device in a semiconductor processing system, comprising:
setting a gas flow with the flow control device;
flowing the gas from the flow control device through an orifice having substantially the same flow resistance as a processing chamber into a sensing circuit;
flowing the gas into a volume of the sensing circuit;
sensing at least one property and/or attribute of the gas in the volume;
resolving a flow rate and/or pressure of the gas entering the sensing circuit from the sensed property and/or attribute; and
comparing a flow determined using the sensing circuit with the setting of the flow control device.

### Claim 10 (depends on 9)

The method of claim 9, wherein the volume of the sensing circuit is a calibrated volume.

### Claim 11 (depends on 9)

The method of claim 9, wherein the volume of the sensing circuit is a non-calibrated volume.

### Claim 12 (depends on 11)

The method of claims 11, wherein resolving the flow rate and/or pressure of the gas entering the sensing circuit is determined without using a known volume upstream of the sensing circuit.

### Claim 13

A method for calibrating a flow control device, comprising:
setting a gas flow with the flow control device;
flowing the gas from the flow control device through an orifice having substantially the same flow resistance as a processing chamber into a sensing circuit;
comparing a flow determined using the sensing circuit with the setting of the flow control device; and
sampling a characteristic of a gas present in the sensing circuit until an endpoint is reached.

### Claim 14 (depends on 13)

The method of claim 13, wherein sampling further comprises:
sampling until a confidence limit is reached.

### Claim 15 (depends on 13)

The method of claim 13, wherein sampling further comprises:
sampling until data converges within a predetermined range.

### Claim 16 (depends on 13)

The method of claim 13, wherein sampling further comprises:
sampling at a frequency rate of less than about 5 millisecond.

### Claim 17

A method for providing a process gas in a semiconductor processing system, comprising:
providing a processing system having a gas source coupled to a processing chamber and sensing circuit, the sensing circuit having substantially the same flow resistance as the processing chamber;
setting a flow control device to provide a flow of process gas from the gas source at target rate, the target rate being a predefined rate selected for substrate processing in the processing chamber, the flow exiting the flow control device being at an actual rate;
flowing the process gas at the actual rate into the sensing circuit while bypassing the processing chamber;
sensing a metric indicative of the actual flow rate;
adjusting the setting of the flow control device to correct differences between the actual rate and the target rate; and
flowing the process gas from the flow control device into the processing chamber and processing a substrate therein.

### Claim 18 (depends on 17)

The method of claim 17, wherein sensing further comprises:
flowing the process gas into a calibrated volume; and
measuring at least one property and/or attribute of the process gas in the calibrated volume from which a flow rate and/or pressure of the process gas entering the sensing circuit may be resolved.

### Claim 19 (depends on 17)

The method of claim 17, wherein sensing further comprises:
flowing the process gas into a non-calibrated volume; and
measuring changes in at least one property and/or attribute of the gas in the non-calibrated volume from which a flow rate and/or pressure of the gas entering the sensing circuit may be resolved.

### Claim 20 (depends on 17)

The method of claim 17, wherein sensing further comprises:
sampling a characteristic of a gas present in the sensing circuit until at least one of an endpoint is reached, a confidence limit is reached or data converges within a predetermined range.