Foley & Lardner
Method of producing bonded substrate with silicon-on-insulator structure
 Two wafers of single-crystal silicon are used to produce a bonded substrate having a silicon-on-insulator (SOI) structure. In a principal surface of a first wafer, a number of first insulator film patterns of equal thickness art formed for isolation of semiconductor devices to be fabricated on the bonded substrate. Simultaneously, at least to second insulator film patterns having the same thickniess as the first insulator film patterns are formed in the same surface of the first wafer for optical measurement of the thickness of an active layer of in the bonded substrate. Then the first wafer is bonded to a second wafer to obtain a bonded substrate in which the insulator film patterns are buried adjacent to the interface between the two silicon wafers. To form an active layer having a desired thickness above the buried insulator film patterns, the thickness of the first wafer is reduced by mechanical grinding and chemical-mechanical polishing. The polishing operation is intermitted at suitable time intervals, and the thickness of the active layer is measured by an optical method in the area of each of the second insulator film patterns while the polishing operation is intermitted. 
NEC Corporation
Y H
Y10S H01L
additional inventional
Tomohiro Hiroaki
Hamajima Kikuchi