AVS 47th International Symposium
    Plasma Science and Technology Friday Sessions
       Session PS-FrM

Paper PS-FrM2
Kinetic Suppression of Process Gas/Silicon Substrate Reactions During the Remote Plasma-assisted Deposition of Al@sub2@O@sub3@ and Ta@sub2@O@sub5@ on Hydrogen Terminated Silicon Substrates

Friday, October 6, 2000, 8:40 am, Room 310

Session: Dielectrics II
Presenter: R.S. Johnson, North Carolina State University
Authors: R.S. Johnson, North Carolina State University
H. Niimi, North Carolina State University
J.G. Hong, North Carolina State University
G. Lucovsky, North Carolina State University
Correspondent: Click to Email
Deposition of alternative gate dielectrics such as Al@sub2@O@sub3@, Ta@sub2@O@sub5@, Zr(Hf)O@sub2@ and Zr(Hf)O@sub2@-SiO@sub2@ alloys onto H-terminated silicon by chemical vapor deposition, CVD, direct plasma-enhanced CVD, and/or atomic layer deposition, is generally accompanied by subcutaneous growth of interfacial SiO@sub2@ or metal silicate layers that significantly increase equivalent oxide thickness, EOT. Previous studies have shown that silicon substrate/process gas reactions could be effectively suppressed in remote plasma-enhanced CVD, RPECVD, of SiO@sub2@, Si@sub3@N@sub4@ and Si-oxynitride alloys by deposition reaction pathway control. Two aspects of RPECVD contributing to suppression of substrate reactions are i) downstream injection of silicon and metal atom precursors which prevents their fragmentation into reactive species in the gas phase, and ii) fast CVD reactions between unexcited precursors and upstream, plasma-activated oxygen with growth rates > 3-5 nm/minute. Substrate/process gas reactions have been studied by interrupted RPECVD processing-analysis cycles using on-line Auger electron spectroscopy, AES, in a UHV-compatible multi-chamber system. RPECVD of Al@sub2@O@sub3@ and Ta@sub2@O@sub5@ on H-terminated Si, using metal-organic precursors with deposition rates > 5.0 nm/minute effectively suppresses substrate/process gas reactions. Based on AES spectra and capacitance-voltage data, subcutaneous interfacial growth contributes less than 0.5 nm to EOT. In contrast, attempts to deposit ZrO@sub2@-SiO@sub2@ alloys by RPECVD from a Zr(IV)-t-butoxide source at significantly reduced deposition rates, < 1 nm/minute, leads to Si substrate/process gas reactions with Zr silicate subcutaneous interfacial layers adding ~ 1-2 nm to EOT.