Electron cyclotron resonance chemical vapor deposited silicon nitride for T-gate passivation

SiNx deposited by electron cyclotron resonance chemical vapor deposition (E CRCVD) was successfully employed for 0.25 mu m T-gate passivation. The SiNx film showed excellent step coverage, and the device was passivated with an 800 Angstrom SiNx film, which minimized the increase of extrinsic gate cap acitance due to the additional dielectric layer covering the intrinsic devi ce. The SiNx deposition temperature was kept at 50 degrees C (compatible wi th conventional lithography processes) and a pattern of 1500 Angstrom SiNx was lifted off with AZ 5209 resist. Due to the higher efficiency of ion gen eration for the ECRCVD system, a dilute silane/nitrogen mixture was used to deposit the SiNx instead of silane/ammonia. From atomic force microscopy d ata, the deposited SiNx also planarized the deposition surface. The root me an square roughness of a 4 in. silicon wafer was reduced from 6.29 to 2.50 Angstrom after a 2000 Angstrom SiNx deposition. (C) 1998 The Electrochemica l Society. S1099-0062(98)04-074-7. All rights reserved.