(19)

(11)

EP 0 349 622 A1

(12)

(43) Date of publication: 10.01.1990 Bulletin 1990/02 (21) Application number: 89900278.0 (22) Date of filing: 01.12.1988

(51) International Patent Classification (IPC):  H01L 27/ 082( . ) H01L 27/ 02( . ) H01L 21/ 8226( . ) (86) International application number: PCT/GB1988/001051 (87) International publication number: WO 1989/006049 (29.06.1989 Gazette 1989/14)

(84) Designated Contracting States: DE FR GB IT NL (30) Priority: 17.12.1987 GB 19870029417 (71) Applicant: PLESSEY OVERSEAS LIMITED Ilford Essex IG1 4AQ (GB)	(72) Inventor: COWLEY, Nicholas, Paul Wiltshire (GB) (74) Representative: Elliott, Frank Edward  The Plessey Company plc. Intellectual Property Department Vicarage Lane Ilford, Essex IG1 4AQ Ilford, Essex IG1 4AQ (GB)