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MATERIALS RESEARCH

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Microstructural investigation of low temperature chemical vapor deposited 3C-SiCyySi thin films using single-source precursors B-T. Lee, D-K. Kim, C-K. Moon, and J. K. Kim Chonnam National University, Kwangju 500-757, Korea

Y. H. Seo, K. S. Nahm, and H. J. Lee Chonbuk National University, Chonju, Korea

K-W. Lee, K-S. Yu, and Y. Kim Korea Research Institute of Chemical Technology, Taejon, Korea

S. J. Jang Dongshin University, Naju, Korea (Received 13 January 1997; accepted 8 April 1998)

Transmission electron microscopy (TEM) was utilized to investigate microstructures of heteroepitaxial SiCySi films, grown from single-source precursors such as tetramethylsilane [TMS, Si(CH3 )4 ], hexamethyldisilane [HMDS, Si2 (CH3 )6 ], and 1,3-disilabutane [1,3-DSB, H3 SiCH2 SiH2 CH3 ]. In the case of TMSyH2 and HMDSyH2 samples, SiCySi films grown at relatively high precursor concentration and/or low temperatures showed columnar grains with a high degree of epitaxial relationship with the Si substrate. Higher quality films with larger grains were observed in the case of high temperature and/or low precursor concentration samples, although a high density of interfacial voids was observed. Samples grown from pure 1,3-DSB at a low pressure showed high quality single crystalline films with few interfacial voids. It was suggested that the microstructural behavior of these films closely resembles that of the SiC films formed during the carbonization of Si surfaces by the pyrolysis of hydrocarbons, in which the nucleation rate of the film at the initial stage plays a key role. The improvement achieved during the 1,3-DSB growth is proposed to be due to the low growth pressure and the 1 : 1 ratio of Si and C associated with this precursor. I. INTRODUCTION

Silicon carbide is a leading semiconducting material for the high temperature, high frequency, and/or high power applications, with excellent properties such as high electron mobility, large breakdown voltage, good thermal conductivity, and high chemical stability. Chemical vapor deposition (CVD) has been mainly used to grow heteroepitaxial cubic (3C) SiC films on Si. Two different source gases are used in general, diluted in hydrogen, one containing carbon (such as C2 H4 and C3 H8 ) and the other containing silicon (such as SiH4 and SiCl4 ), and single crystal SiC films have been obtained.1,2 High growth temperature of about 1300–1400 ±C is required to crack the carbon-containing gases, however, which may introduce temperature related strains and defects.3 – 9 Compatibility with the underlying Si substrate is also seriously impaired due to the high growth temperature. Furthermore, this process involves SiH4 gases, which is extremely pyrophoric.3 – 9 It has been recently reported that 3C-SiCySi films could be grown at substantially lower temperatures of 900–1200 ±C without using SiH4 , by utilizing alkylsilicon single-source precursors such as methylsilane [SiH3 (CH3 )],3 tetramethylsilane [TMS, Si(CH3 )4 ],4 silacyclorobutane [SCB, c-C3 H6