Method and apparatus for wafer detection

• US 6,377,060 B1
• Filed: 04/18/2000
• Issued: 04/23/2002
• Est. Priority Date: 06/11/1997
• Status: Expired due to Term

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Burkhart, Vincent E., Manaoharlal, Deepak
• Primary Examiner(s): Karlsen, Ernest
• Assistant Examiner(s): TANG, MINH NHUT
• Application Number:
  US09/552,458
• Time in Patent Office: 735 Days
• Field of Search: 324/754, 324/758, 324/662, 324/756, 361/234, 736/30
• US Class Current: 324/756.01
• CPC Class Codes: H01L 21/67259 Position monitoring, e.g. misposition detection or presence detection
• CPC Class Codes: H01L 21/67288 Monitoring of warpage, curvature, damage, defects or the like
• CPC Class Codes: H01L 21/68 for positioning, orientation or alignment
• CPC Class Codes: H02N 13/00 Clutches or holding devices using electrostatic attraction, e.g. using Johnson-Rahbek effect

Abstract

An apparatus and a method for detecting the presence and position of a wafer upon a semiconductor wafer support pedestal surface. Specifically, a wafer detector comprising a plurality of electrodes on a surface of the wafer support pedestal. The electrodes are coupled to a capacitance measurement circuit that measures the capacitance between the electrodes and generates a signal corresponding to a wafer'"'"'s presence, location and chucking condition. The wafer'"'"'s presence completes an electrical circuit between the electrodes, increasing the capacitance between the electrodes. As such, the presence of a wafer, the position of the wafer, and the condition of the wafer, i.e., wafer damage, can be detected upon a wafer support pedestal during wafer processing.

Claims

1. A method for detecting a wafer on a surface of a semiconductor wafer support pedestal comprising the steps of:

providing a plurality of surface electrodes on the surface of the semiconductor wafer support pedestal disposed in a circular pattern about the circumference of the semiconductor wafer support pedestal;

monitoring a capacitance between the circumferentially disposed surface electrodes in said plurality of electrodes;

positioning a wafer onto the surface of the semiconductor wafer support pedestal;

identifying a change in capacitance between the circumferentially disposed surface electrodes in said plurality of electrodes, where the change in capacitance is indicative of the presence of a wafer upon the surface of the semiconductor wafer support pedestal.

2. The method of claim 1 wherein said plurality of electrodes are arranged in electrode pairs, forming a plurality of electrode pairs, and said monitoring step further comprises the step of monitoring a capacitance between each electrode pair of said plurality of electrode pairs.

3. The method of claim 1 further comprising the steps of:

clamping said wafer to said semiconductor wafer support surface; and

monitoring said capacitance between said electrodes for a change in capacitance that indicates that the wafer is clamped.

4. The method of claim 3 wherein said clamping step further comprises the step of applying a chucking voltage to at least one electrode embedded beneath the surface of said semiconductor wafer support pedestal to clamp said wafer to said pedestal by electrostatic force.

5. A method for detecting a wafer on a surface of a semiconductor wafer support pedestal comprising the steps of:

providing a plurality of surface electrodes on the surface of the semiconductor wafer support pedestal and at least one electrode embedded beneath the surface of said semiconductor wafer support pedestal;

monitoring a capacitance between the surface electrodes and the at least one embedded electrode;

positioning a wafer onto the surface of the semiconductor wafer support pedestal;

identifying a change in capacitance between the surface electrodes and the at least one embedded electrode, where the change in capacitance is indicative of the presence of a wafer upon the surface of the semiconductor wafer support pedestal.

6. The method of claim 5 further comprising the steps of:

clamping said wafer to said semiconductor wafer support surface; and

monitoring said capacitance between said surface electrodes and said at least one embedded electrode for a change in capacitance that indicates that the wafer is clamped.

7. The method of claim 6 wherein said clamping step further comprises the step of applying a chucking voltage to the at least one embedded electrode to clamp said wafer to said pedestal by electrostatic force.

8. A method for determining the position of a wafer on a wafer support pedestal comprising the steps of:

providing the wafer support pedestal with a plurality of electrodes disposed in a circular pattern about the circumference of the semiconductor wafer support pedestal;

monitoring a capacitance between the electrodes in said plurality of electrodes;

positioning a wafer onto a surface of the semiconductor wafer support pedestal;

identifying a change in a capacitance between the electrodes in said plurality of electrodes, where the change in said capacitance is indicative of a position of a wafer upon the surface of the semiconductor wafer support pedestal.

9. The method of claim 8 wherein said plurality of electrodes are arranged in electrode pairs, forming a plurality of electrode pairs, and said monitoring step further comprises the step of monitoring a capacitance between each electrode pair of said plurality of electrode pairs.

10. The method of claim 9 wherein said electrode pairs are positioned equilaterally about the circumference of the wafer support pedestal.

11. The method of claim 10 wherein, when the wafer is centered, each of said pairs of electrodes of said plurality of electrode pairs has substantially the same capacitance.

12. The method of claim 8 wherein said plurality of electrodes comprises at least one surface electrode located upon said surface of the semiconductor wafer support pedestal.