AVS 46th International Symposium
    Plasma Science and Technology Division Friday Sessions
       Session PS-FrM

Paper PS-FrM10
Ultra-Low-Temperature Formation of Silicon Nitride Gate Dielectric Films by Novel Plasma Technique

Friday, October 29, 1999, 11:20 am, Room 609

Session: Emerging Plasma Applications
Presenter: M. Hori, Nagoya University, Japan
Authors: M. Hori, Nagoya University, Japan
H. Ohta, Nagoya University, Japan
A. Nagashima, Nagoya University, Japan
M. Ito, Wakayama University, Japan
T. Goto, Nagoya University, Japan
Correspondent: Click to Email
As device dimensions shrink below 100nm in ULSI, the thickness of gate dielectric film (SiO@sub2@) in FETs will fall to be 2-3nm range. The SiO@sub2@ film is replaced by a dielectric film with a higher dielectric constant film. In this study, we have successfully formed the ultra thin silicon nitride (SiN@subx@) films of 5nm in thickness at a low temperature of 300 degree C by the novel plasma technique using ECR SiH@sub4@/N@sub2@ plasma enhanced CVD (PECVD), where the charged species incident on the substrate were removed by two permanent magnets set above the substrate. It enabled us to form SiN@subx@ films by only neutral radicals. The experimental conditions were 0.5Pa, 300W, SiH@sub4@/N@sub2@ of 5/100sccm, and a substrate bias of floating. The films indicated the low leakage current of 7x10@super-8@A/cm@super2@ at 3MV/cm, dielectric constant of 7.3 and near stoichiometry composition. The reaction mechanism of film deposition with and without charged species were investigated by in-situ XPS and in-situ FT-IR reflection absorption spectroscopy. In the case of without charged species, two absorption bands ascribed to Si-N stretching mode at 970cm@super-1@ and 1085 cm@super-1@ were observed. The low frequency component is probably due to the metastable layer and the high one is due to the SiN@subx@ network. On the other hand,with charge species, the only low component was observed. The metastable layer is considered to cause the degradation of electrical properties of films. On the basis of these results, the control of ion bombardment on the growth was found to be a key factor for forming ultra thin SiN@subx@ films of high quality at a low temperature in PECVD.