Low pressure chemical vapor deposition of B-N-C-H films from triethylamine borane complex

Abstract

In this study, films consisting of B-N-C-H have been synthesized by low pressure chemical vapor deposition using the liquid precursor triethylamine borane complex (TEAB) both with and without ammonia. When no NH3 is present, the growth rate was observed to follow an Arrhenius behavior in the temperature range of 600 to 800 °C with an apparent activation energy of 11 kcal/mol. A linear dependence of growth rate is observed as a function of square root of flow rate for the TEAB range of 20 to 60 sccm, indicating that the reaction rate is controlled by the adsorption of borane. The addition of NH3 to TEAB had the effect of lowering the deposition temperature down to 300 °C and increasing the apparent activation energy to 22 kcal/mol. Above 650 °C, the carbon concentration of the deposits increased significantly, reflecting the breakup of the amine molecule. X-ray diffraction measurements indicated the films to be in all cases amorphous. Infrared spectra of the films showed absorption peaks representing the vibrational modes of B-N, B-N-B, B-H, and N-H. The index of refraction varied between 1.76 and 2.47, depending on composition of the films. Films deposited with no NH3 above 700 °C were seen to be compressive while films below that temperature were tensile. In the range of 350 to 475 °C, the addition of NH3 to TEAB resulted in films that were mildly tensile, while below 325 °C and above 550 °C, the films were found to be compressive. Both the hardness and Young's modulus of the films decreased with higher temperatures, reflecting the influence of the carbon presence.

The search for novel, superhard materials

“…The first report of the deposition of the ternary BC x N y films by thermal CVD was by Badzian et al 131 who also used microwave plasma for this process and obtained deposits with a cubic modification as was seen by x-ray diffraction ͑XRD͒. 132 The plasma activated CVD was also used later on by Montasser et al, 133,134 Levy et al, 135 and by Besmann 136 who achieved a hardness between 4 and 33 GPa depending on the deposition conditions. Further work has shown that, similar to the deposition of hard a-C:H diamond-like hard carbon ͑DLHC͒ and c-BN, the high hardness of the BC x N y films requires an appropriate ion bombardment and an elevated deposition temperature.…”

Evolution of microstructure and formation mechanism of Nd-Fe-B nanoparticles prepared by low energy consumption chemical method

“…Then, the (C 2 H 5 ) 3 N-BH 3 bond fractured and the H atom in BH 3 À began to break apart (thermal decomposition temperature: 260-350 C), [31][32][33][34][35] which partly participated in the reduction of the oxide nucleus, to form the simple metal nucleus (M). 36,37 Moreover, as the oleamine solution was weakly alkaline, the following reactions likely occurred: 38,39…”

Compilation on Synthesis, Characterization and Properties of Silicon and Boron Carbonitride Films

“…In the study of Levy et al, films consisting of B-N-C-H have been synthesized by LPCVD using the liquid precursor TEAB = (C 2 H 5 ) 3 N⋅BH 3 complex both with and without ammonia (Levy et al, 1995). In the absence of NH 3 , the growth rate dependency on temperature follows an Arrhenius behaviour with an apparent activation energy of 11 kcal/mole.…”