Decomposition processes of H3NBH3 (borazane), (BH)3(NH)3 (borazine), and B(CH3)3 (trimethylboron) on heated W wire surfaces

Abstract

a b s t r a c tThe decomposition mechanisms of H 3 NBH 3 , (BH) 3 (NH) 3 , and B(CH 3 ) 3 on heated W wire surfaces were examined using mass spectrometric and laser spectroscopic techniques. These chemicals can be source materials for catalytic chemical vapor deposition as well as for B-atom doping. All the species could be decomposed well when the wire temperature was over 2.0 × 10 3 K. When H 2 was introduced, the production of B atoms was confirmed in the decomposition of H 3 NBH 3 and B(CH 3 ) 3 , but not for (BH) 3 (NH) 3 . H 3 NBH 3 and B(CH 3 ) 3 may be candidates as safe precursors for B-atom doping, while (BH) 3 (NH) 3 could be a viable candidate as a BN film precursor.

A Clean Source of B atoms without Using Explosive Boron Compounds

“…borazane, can be decomposed efficiently on hot-wire surfaces and that this can be a safer source material for B-atom doping. 3,4 NH 3 BH 3 is decomposed to NH 3 and BH 3 , while BH 3 can be converted to B atoms in gas-phase reactions with H atoms. H atoms can easily be produced from H 2 on heated wire surfaces.…”

“…H atoms can easily be produced from H 2 on heated wire surfaces. 5,6 Although the vapor pressure of NH 3 BH 3 is low, around 0.01 Pa at room temperature, the B-atom density produced from NH 3 BH 3 can be increased up to 310 11 cm -3 by heating the NH 3 BH 3 reservoir to 350 K. This density is comparable to that produced by the catalytic decomposition of B 2 H 6 /H 2 , 4,7 and sufficient for doping to semiconductor substrates. One problem with this boron-nitrogen-hydrogen compound is the possible contamination by N atoms.…”

“…The experimental procedure and apparatus for this study were similar to those described elsewhere. 3,4,7 NH 3 BH 3 was effused into a cylindrical chamber from its reservoir. H 2 could be used as a carrier gas, with its flow rate controlled by a mass flow controller (Horiba STEC, SEC-40M).…”

“…The absolute B-atom density was similar to that for NH 3 BH 3 , and was higher than that reported in our previous paper, 1.110 11 cm -3 . 4 This difference can be ascribed to the difference in boronization temperatures. In the present work, W wires were boronized at 2.2910 3 K, while the temperature was typically 2.0510 3 introducing He.…”

“…NH 3 BH 3 can be decomposed well even in the absence of a H 2 flow, but the production of B atoms is minor. 3,4 In other words, NH 3 BH 3 should be decomposed to NH 3 and BH 3 on wire surfaces, but the H-atom density in the gas phase is too low to produce B atoms efficiently. The slow boronization in the absence of H 2 suggests that BH x (0≤x≤2), presumably B, is responsible for the boronization and BH 3 plays only a minor role.…”