The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 21, 1995
Filed:
Sep. 29, 1993
Motorola Inc., Schaumburg, IL (US);
Abstract
A chemical-mechanical-polishing process in which acoustic waves are generated in the polishing slurry (18) to enable detection of an end-point in the polishing process, and to continuously clean the surface of a polishing pad (14) in a polishing apparatus (10). Acoustic waves are generated in the polishing slurry (18) by submerging a transducer (28) in the polishing slurry (18). The transducer (28) is powered by a voltage amplifier (30) coupled to a frequency generator (32). The frequency of the acoustic waves is adjusted by the frequency generator (32) to obtain optimum wave generation in the polishing slurry (18). The end-point of the polishing process is detected by a change in the acoustic wave velocity in the polishing slurry (18), which occurs when the slurry composition changes at end-point. The wave velocity is monitored by a receiver (34) submerged in the polishing slurry (18) at a predetermined distance from the transducer (28). Additionally, the acoustic wave frequency can be adjusted by the frequency generator (32) to induce sonic vibration in the polishing pad (14) such that continuous cleaning action is attained on the surface of the polishing pad (14).