Boron doped diamond deposited by microwave plasma-assisted CVD at low and high pressures

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Boron doped diamond is deposited over a range of pressures and chemistries including pressures from 35–120 Torr and gas chemistries including hydrogen–methane–diborane and argon–methane–hydrogen–diborane mixtures. The diamond deposition system is a 2.45 GHz microwave resonant cavity system. Diborane (B 2H 6) gas chemistry has been utilized with flow rates of 2.5–100 ppm. At low pressures of 35 Torr polycrystalline films are deposited using a feed gas mixture of hydrogen and 0.5% methane. At moderate pressures of 95 Torr, diamond films are grown using 60% Ar, 39% H 2 and 1% CH 4. For the high pressure experiments of 120 Torr, polycrystalline films are deposited using 98% H 2 and 2% CH 4. The deposition rate ranges from 0.3 to 1.6 μm/h. This investigation describes the relationship of the diborane flow rate and pressure versus the resulting film morphology, electrical properties, and morphology of the deposited films. The deposition of boron-doped polycrystalline diamond is done on 5 cm diameter silicon and silicon dioxide coated substrates. The resistivity spatial variation across the wafer was ± 5% indicating a good uniformity.