DEVICE AND METHOD FOR COMPENSATING A CAPACITIVE SENSOR MEASUREMENT FOR VARIATIONS CAUSED BY ENVIRONMENTAL CONDITIONS IN A SEMICONDUCTOR PROCESSING ENVIRONMENT

• US 20090015268A1
• Filed: 07/09/2008
• Published: 01/15/2009
• Est. Priority Date: 07/13/2007
• Status: Abandoned Application

• Current Assignee: CyberOptics Semiconductor, Inc. (Nordson Corporation)
• Original Assignee: CyberOptics Semiconductor, Inc. (Nordson Corporation)
• Inventors: Gardner, DelRae H., Lim, Andy K.
• Application Number:
  US12/169,737
• Publication Number:
  US 20090015268A1
• 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: H01L 21/67069 for drying etching
• CPC Class Codes: H01L 21/67253 Process monitoring, e.g. flow or thickness monitoring
• CPC Class Codes: H01L 21/67259 Position monitoring, e.g. misposition detection or presence detection

Abstract

A method of sensing proximity to a showerhead in a semiconductor-processing system is provided. The method includes measuring a parameter that varies with proximity to the showerhead, as well as with at least one external factor. The method also includes measuring a parameter that does not vary with proximity to the showerhead, but does vary with the at least one factor. A compensated proximity output is calculated based upon the measured parameters and is provided as an output.

Claims

1. A method of sensing proximity to a showerhead in a semiconductor-processing system, the method comprising:

providing a first sensing capacitive plate that is operably supported by a substrate support pedestal;

providing a second sensing capacitive plate that forms a sensing capacitor with the first sensing capacitive plate, wherein the sensing capacitor has a capacitance that varies with distance between the substrate support pedestal and the showerhead and also varies with at least one external factor;

providing first and second reference capacitive plates to form a reference capacitor having a reference capacitance that does not vary with distance between the substrate support pedestal and the showerhead, but does vary with the at least one external factor;

measuring the capacitance of the sensing capacitor;

measuring the capacitance of the reference capacitor;

providing an output relative to the proximity of the showerhead based upon the capacitance of the sensing and reference capacitances.

2. The method of claim 1, wherein the second sensing capacitance plate is operably supported by the substrate support pedestal.

3. The method of claim 1, wherein the at least one external factor includes temperature.

4. The method of claim 1, wherein the at least one external factor includes relative humidity.

5. The method of claim 1, wherein the at least one external factor includes a plurality of external factors.

6. The method of claim 1, wherein the output is calculated by a controller.

7. The method of claim 1, wherein measuring the capacitance of the reference capacitor occurs periodically.

8. The method of claim 1, and further comprising scaling the measured reference capacitance.

9. A method of sensing proximity to a showerhead in a semiconductor-processing system, the method comprising:

measuring a parameter that varies with proximity to the showerhead, as well as with at least one external factor;

measuring a parameter that does not vary with proximity to the showerhead, but does vary with the at least one factor;

calculating a compensated proximity output based upon the measured parameters; and

providing the calculated proximity output.

10. The method of claim 9, wherein the method is performed by a sensor resting upon a substrate support pedestal.

11. The method of claim 10, wherein the external factor includes at least one factor from the group consisting of temperature, relative humidity, and sensor age.

12. A sensor for sensing proximity to a showerhead in a semiconductor processing system, the sensor comprising:

a controller;

capacitance measurement circuitry operably coupled to the controller;

a proximity sensing capacitor operably coupled to the capacitance measurement circuitry;

a reference capacitor operably coupled to the capacitance measurement circuitry; and

wherein the controller is configured to provide a compensated proximity output based upon a sense capacitance and a reference capacitance.

13. The sensor of claim 12, wherein the proximity sensing capacitor is formed from a plurality of capacitive plates disposed on the sensor.

14. The sensor of claim 13, wherein the reference capacitor is formed of a plurality of capacitive plates disposed within the sensor on a circuit board of the sensor.

15. The sensor of claim 12, wherein the proximity sensing capacitor and the reference capacitor have the same nominal capacitance.

16. The sensor of claim 12, and further comprising switching circuitry operably coupled to the controller, the capacitance measurement circuitry, the proximity sensing capacitor and the reference capacitor.

17. The sensor of claim 12, and further comprising a temperature sensor operably coupled to the controller.