(19)

(11)

EP 0 268 654 A1

(12)

(43) Date of publication: 01.06.1988 Bulletin 1988/22 (21) Application number: 87903799.0 (22) Date of filing: 27.05.1987

(51) International Patent Classification (IPC):  H01L 29/ 78( . ) H01L 21/ 285( . ) H01L 21/ 28( . ) H01L 21/ 336( . ) (86) International application number: PCT/US1987/001230 (87) International publication number: WO 1987/007763 (17.12.1987 Gazette 1987/28)

(84) Designated Contracting States: BE DE FR GB IT NL (30) Priority: 16.06.1986 US 19860874475 (71) Applicant: AT&T Corp. New York, NY 10013-2412 (US)	(72) Inventors: GALLAGHER, Patrick, Kent Basking Ridge, NJ 07920 (US) GREEN, Martin, Laurence New Providence, NJ 07974 (US) LEVY, Roland, Albert Murray Hill, NJ 07974 (US) (74) Representative: Blumbach Weser Bergen Kramer Zwirner Hoffmann Patentanwälte  Radeckestrasse 43 D-81245 München D-81245 München (DE)