Plasma enhanced chemical vapor deposition of silicon nitride films from a metal-organic precursor
- PDF / 308,642 Bytes
- 3 Pages / 576 x 792 pts Page_size
- 67 Downloads / 215 Views
Plasma enhanced chemical vapor deposition of silicon nitride films from a metal-organic precursor David M. Hoffmana) and Sri Prakash Rangarajan Department of Chemistry, University of Houston, Houston, Texas 77204-5641
Satish D. Athavale, Shashank C. Deshmukh, and Demetre J. Economoua) Department of Chemical Engineering, University of Houston, Houston, Texas 77204-4792
Jia-Rui Liu, Zongshuang Zheng, and Wei-Kan Chu Texas Center for Superconductivity, University of Houston, Houston, Texas 77204-5932 (Received 4 October 1993; accepted 30 August 1994)
Silicon nitride films are grown by plasma enhanced chemical vapor deposition from tetrakis(dimethylamido)silicon, Si(NMe2)4, and ammonia precursors at substrate temperatures of 200-400 °C. Backscattering spectrometry shows that the films are close to stoichiometric. Depth profiling by Auger electron spectroscopy shows uniform composition and no oxygen or carbon contamination in the bulk. The films are featureless by scanning electron microscopy under 100,000 X magnification.
Silicon nitride thin films are used in microelectronic device fabrication as an interlevel dielectric, as a mask for ion implantation, oxidation, or diffusion, and for device passivation.1 They have been prepared at high substrate temperatures (700-900 °C) by pyrolytic deposition in a hydrogen atmosphere from silane and ammonia precursors2'3 and by low pressure chemical vapor deposition from dichlorosilane and ammonia precursors.4-5 Silicon nitride films have also been deposited by remote and direct plasma enhanced chemical vapor deposition (PECVD) techniques from silane and either ammonia or nitrogen,6"8 and recently from a disilanyl amine and ammonia.9 The PECVD processes allow lower temperatures of deposition (150-400 °C) than the thermal processes, an advantage when using thermally sensitive substrates such as those found in microelectronics applications. Recently, the preparation of silicon nitride films by atmospheric pressure chemical vapor deposition from tetrakis(dimethylamido)silicon, Si(NMe2)4, and ammonia precursors has been reported.10 Also, Si(NMe2)4 and NH3 or N2 have reportedly been used in a LPCVD multiwafer system (with or without plasma excitation) to deposit films, but stoichiometry and film properties were not given.11 Si(NMe2)4 has attractive features that make it a promising CVD reagent. It is, for example, a volatile liquid (bp 180 °C at 760 mm Hg, 74.5 °C
at 19 mm Hg) that can be readily prepared in large quantities from inexpensive reagents and purified by distillation.10 Importantly, it is only moderately air sensitive and therefore much safer to handle than silane, the conventional silicon CVD precursor. We show in this report that Si(NMe2)4 can be used in a plasma enhanced chemical vapor deposition process to deposit nearly stoichiometric silicon nitridefilmsat low substrate temperatures without carbon or oxygen contamination. Depositions were carried out using a low pressure cold wall tubular reactor with a 3.5 cm inside diameter (Fig. 1). The plasma was excited with
Data Loading...
