Measuring the surface properties of polishing pads using ultrasonic reflectance
AssigneePsiloQuest, Inc.
InventorYaw S. Obeng
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Abstract
The present invention provides a system and method for measuring the surface properties of polishing pads using noncontact ultrasonic reflectance. An ultrasonic probe is located over the polishing surface and configured to both transmit an ultrasonic signal to the polishing surface and receive a modified ultrasonic signal from the polishing surface without contacting the polishing surface. A subsystem coupled to the ultrasonic probe is configured to determine a surface property of the polishing pad from the modified signal.
Claims10
A method for measuring the surface properties of a polishing pad, comprising:
- situating an ultrasonic probe above a polishing surface of a polishing pad, without contacting said polishing surface;
- transmitting an ultrasonic signal from said probe to said polishing surface, said ultrasonic signal being modified by said polishing surface;
- and
- receiving said modified signal by said ultrasonic probe,
- wherein said modified signal is a reflected signal used to calculate an acoustic reflectance spectrum of said polishing surface.
A method for measuring the surface properties of a polishing pad, comprising:
- situating an ultrasonic probe above a polishing surface of a polishing pad, without contacting said polishing surface;
- transmitting an ultrasonic signal from said probe to said polishing surface, said ultrasonic signal being modified by said polishing surface;
- and
- receiving said modified signal by said ultrasonic probe,
- wherein said modified signal is a transmission signal used to determine a relative density of said polishing surface.
Dependencies are inferred from the claim text.