1. Device Technology Division, Memory Device Department, Electronic Devices Group, Fujitsu Limited, 4‐2 Nishinemoriyama, Kanegasaki‐cho, Isawa‐gun, Iwate 029‐45, Japan
2. Thin‐Film Deposition Development Division, Process Engineering Department, Electronic Devices Group, Fujitsu Limited, 1015 Kamikodanaka, Nakahara‐ku, Kawasaki 211, Japan
3. Process Development Division, Process Engineering Department, Electronic Devices Group, Fujitsu Limited, 1015 Kamikodanaka, Nakahara‐ku, Kawasaki 211, Japan