Inventors:
Jeffrey T. Koze - Whitehall PA
Anton J. Miller - Lehigh County PA
Assignee:
AT&T Bell Laboratories - Murray Hill NY
International Classification:
H01L 21306
B44C 122
C03C 1500
C03C 2506
Abstract:
An improvement in silicon wafer flatness is obtained by reducing the time spent in polishing the wafer. After a conventional lapping operation, the wafer is coated with an etch resistant coating, typically silicon nitride. A polishing step removes the nitride coating on the flat surfaces of the wafer, but leaves a nitride coating on the sides of pits that are formed in the lapping operation. The wafer is then etched, typically in KOH, to remove the silicon surface to below the depth of the pits. The undercutting of the nitride coating removes the pits, or leaves relatively small protrusions in their place. The protrusions may be removed by a short polishing operation. Other wafer types and etch-resistant materials are possible. Integrated circuits are typically formed on the wafers by lithography techniques that advantageously utilize the improved flatness.