(19)

(11)

EP 0 551 323 A1

(12)

(43) Date of publication: 21.07.1993 Bulletin 1993/29 (21) Application number: 91917115.0 (22) Date of filing: 26.09.1991

(51) International Patent Classification (IPC):  H01L 21/ 52( . ) H01L 21/ 58( . ) H01L 21/ 20( . ) H01L 29/ 84( . ) (86) International application number: PCT/GB1991/001659 (87) International publication number: WO 1992/005575 (02.04.1992 Gazette 1992/08)

(84) Designated Contracting States: DE FR GB (30) Priority: 26.09.1990 GB 19900020908 (71) Applicant: BRITISH TECHNOLOGY GROUP LIMITED London SE1 6BU (GB)	(72) Inventor: ROGERS, Tony, William, James 142 Bath Road Berkshire RG3 2EU (GB) (74) Representative: Gaskin, John Shield  Patents Department British Technology Group Ltd 101 Newington Causeway London SE1 6BU London SE1 6BU (GB)