Chlorine Levels in SiO2 Formed Using TCA and LPCVD at Low Temperatures

Abstract

Chlorine distribution in the SiO2-Si system has been studied for two types of Cl-doped oxides, both formed at 900~ (i) thermal oxide grown with a trichloroethane (TCA) additive at 1.0, 2.5, and 4.0 equivalent percent HC1 and (ii) low pressure chemical vapor deposition (LPCVD) oxide, produced by the reaction of SiH2Cl~ and N20 at low pressure. Using SIMS profiles, it was found that C] introduced by TCA oxidation piles up at the interface, reaching a peak of 4-10E18 atom/cm 3. This C1 level proved adequate for metal oxide semiconductor (MOS) device passivation of alkali contamination. Conversely, LPCVD oxide deposited over 1000A SiO2 generates a uniformly high C1 level across the deposited oxide (7-10E19 atom/cm3), but very low concentration at the silicon interface (< 1El8 atom/cm3). Only after a high temperature anneal (1000~ for lh) does this level become similar to the TCA value. However, such a treatment conflicts with the present trend toward reduced temperature processing. Since MOS stability is mainly dependent on interface properties, this behavior suggests that TCA oxidation is more effective than LPCVD for alkali contamination control in MOS integrated circuits fabrication.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 137.99.31.134

Hexachlorodisilane as a Precursor in the LPCVD of Silicon Dioxide and Silicon Oxynitride Films

“…Therefore, within the accuracy of AES (___ 3 a/o) the films appear to be somewhat oxygen-rich. As in the case of Si3N4, the R values used to achieve this stoichiometry lie between those found for and 900~ (9). Chlorine seems to be uniformly distributed throughout the thickness of the film, within the accuracy of AES, with possibly a slight buildup at the Si/SiO2 interface.…”

“…As deposition pressures and temperatures are reduced to suppress homogeneous decomposition and improve deposition uniformity, the importance of these surface interactions increases relative to the homogeneous pyrolysis deposition pathway. Recently it was pointed out that overestimation of the rate of homogeneous silane pyrolysis under low pressure conditions has led to incorrect and misleading conclusions regarding the extent of gas-phase decomposition under low temperature, LPCVD conditions (9). As a result most silane deposition processes are completely controlled by surface chemistry which is, as yet, poorly understood and subject to considerable controversy.…”

“…Since we found Si2C16 capable of producing high quality films of both Si and Si3N4 over a wide range of temperatures, an extension of the investigation to the deposition of SiO2 and silicon oxynitride films would be clearly of interest. Although SiO2 can be deposited at moderate temperatures with nonhazardous precursors such as tetraethoxysilane (TEOS) (3,4) or diacetoxyditeriarybutoxysilane (DADBS) (5,6), higher temperature depositions (>750~ which lead to improved density, uniformity, and conformality, are still carried out using either SiHzC]2-N20 (7)(8)(9)(10)(11)(12)(13) or SiH4-N20 (8,14,15). Silicon oxynitride films are deposited almost exclusively from SiH2C12-N20-NH3 (16-20) or SiH4-NH3-CO2(NO) (21)(22)(23)(24) gas mixtures.…”