Synthesis and Studies of Organometallic Precursors for CVD of Thin Film Electronic Materials

Cyclic molecular systems of the type, AXXBYYn where A, B Al, N or Si, C X, X, Y, Y 11, CH3, etc. and n 2 and 3, were studied as potential single-source precursors for the CVD of AlN and SiC films. These compounds provide the required elements for die product film already covalently bound to one another in a single, volatile molecular source and, in the case of the SiC precursors where n 2, they contain built-in ring-strain energy to lower the decomposition onset temperature. Efforts have included the study of the CH32AlNH23 -- AIN CVD system by mass-spectrometrictime-of-flight measurements and the investigation of substituted disilacyclobutanes as single- source SiC precursors. The mass-spec-TOF studies have indicated that a slow decomposition of the CH32AlNH23 I precursor to produce methane and a series of higher oligomeric products occurs during its vaporization at 75-100 deg C. These oligomeric species are believed to be intermediates formed in the gas- phase thermal decomposition of I to AlN. This precursor was used to deposit high quality AlN films up to 2 micrometers thick on Si and sapphire substrates in a LPCVD apparatus and is being tested for use in the deposition of AlN interface layers in A1203-reinforced metal matrix composites. Disilacyclobutane, SiH2CH22, was found to yield stoichiometric, crack-free, adherent, polycrystalline SiC films on Si 100 and Si 111 surfaces by LPCVD at temperatures as low as 690 OC. Chemical vapor deposition CVD, AIN, SiC, Organometallic precursor.