(19)

(11)

EP 0 561 909 A1

(12)

(43) Date of publication: 29.09.1993 Bulletin 1993/39 (21) Application number: 92900803.0 (22) Date of filing: 11.12.1991

(51) International Patent Classification (IPC):  H01L 21/ 8238( . ) H01L 27/ 092( . ) (86) International application number: PCT/CA1991/000441 (87) International publication number: WO 1992/010851 (25.06.1992 Gazette 1992/14)

(84) Designated Contracting States: DE FR GB IT NL (30) Priority: 12.12.1990 CA 19902032073 (71) Applicant: MITEL CORPORATION Kanata Ontario K2K 1X3 (CA)	(72) Inventor: HUET, Pierre Montreal, Quebec H2P 2P6 (CA) (74) Representative: Heath, Peter William Murray, et al  FRY HEATH & SPENCE The Old College 53 High Street Horley Surrey RH6 7BN Horley Surrey RH6 7BN (GB)