Capacitive distance sensing in semiconductor processing tools

• US 20070222462A1
• Filed: 02/20/2007
• Published: 09/27/2007
• Est. Priority Date: 02/21/2006
• Status: Active Grant

• Current Assignee: CyberOptics Semiconductor, Inc. (Nordson Corporation)
• Original Assignee: CyberOptics Semiconductor, Inc. (Nordson Corporation)
• Inventors: Gardner, DelRae, Ramsey, Craig, Patelzick, Dana
• Granted Patent: US 7,804,306 B2
• Time in Patent Office: Days
• US Class Current: 324/662
• CPC Class Codes: G01B 7/023 for measuring distance between sensor and object G01B7/082 and G01B7/102 take precedence
• CPC Class Codes: G01D 5/2417 by varying separation

Abstract

A wireless sensor includes at least one capacitive plate for sensing a distance relative to an object of interest within a semiconductor-processing environment. The sensor includes an internal power source and wireless communication such that distance and/or parallelism measurements effected using the capacitive plate(s) can be provided wirelessly to an external device.

Claims

1. A sensor for sensing a distance to an object of interest within a semiconductor processing chamber, the sensor including:

a housing;

a power source disposed within the housing;

wireless communication circuitry coupled to the power source;

a controller coupled to wireless communication circuitry and to the power source;

at least one capacitive plate configured to form a capacitor having a capacitance that varies with the distance;

measurement circuitry coupled to the controller and to the at least one capacitive plate, the measurement circuitry being configured to measure the capacitance and provide an indication thereof to the controller; and

wherein the controller is configured to provide an indication relative to the object based at least in part upon the measured capacitance.

2. The sensor of claim 1, wherein the at least one capacitive plate includes an even number of capacitive plates.

3. The sensor of claim 2, wherein a first half of the even number of capacitive plates are driven to a positive excitation voltage, and the other half of the even positive number of capacitive plates are driven to a negative excitation voltage.

4. The sensor of claim 2, wherein a first capacitive plate is coupled to a surface that is extendable to the object of interest, and a second capacitive plate is fixed within the housing, and wherein a capacitor is formed between the first and second plates, the capacitor having a capacitance that varies with the degree to which the surface is extended.

5. The sensor of claim 4, and further comprising an actuator coupled to the surface, the actuator being coupled to the controller to provide a selectable degree of extension.

6. The sensor of claim 4, wherein the sensor is hermetically sealed and the expandable surface is compressed, or expanded, in response to atmospheric pressure, or lack thereof, external to the sensor.

7. The sensor of claim 2, wherein the even number is 2.

8. The sensor of claim 1, wherein the measurement circuitry includes a sigma-delta modulator.

9. The sensor of claim 1, wherein the indication is parallelism.

10. The sensor of claim 9, wherein the indication is provided in a user interface depicting a bubble-like metaphor.

11. The sensor of claim 1, wherein the indication is distance from a platen to a showerhead.

12. The sensor of claim 1, wherein the object of interest is a showerhead within the semiconductor processing chamber.

13. The sensor of claim 1, wherein the wireless communication circuitry is radio-frequency communication circuitry.

14. The sensor of claim 1, wherein the controller is configured to compute a distance between the object of interest and the surface on which the sensor rests based upon the measured capacitance and the known fixed offset distance between the at least one capacitive plate and the surface upon which the sensor rests.

15. The sensor of claim 1, wherein the sensor is embodied within a physical package that is similar to substrates that are processed by the processing chamber.

16. A method of sensing a distance to an object of interest within a semiconductor processing chamber, the method comprising:

bringing a plurality of capacitive plates into proximity of the object of interest;

applying excitation voltages of substantially equal magnitude, but opposite polarity to the plurality of capacitive plates;

sensing the effective capacitance between the plurality of capacitive plates, and the object of interest; and

providing an indication relative to the object based at least in part upon the measured capacitance.

17. The method of claim 16, wherein the indication is distance to the object of interest.

18. The method of claim 16, wherein the indication is parallelism.

19. The method of claim 18, wherein the parallelism is depicted as a bubble-like metaphor.

20. The method of claim 16, wherein the indication is provided wirelessly.

21. The method of claim 16, wherein the object of interest is a showerhead within the semiconductor processing chamber.