Diamond was successfully synthesized using a low pressure, radio frequency (rf), inductively coupled plasma. A source mixture of methanol(CH3OH),hydrogen(H2),and water vapor(H2O)was introduced into a reaction chamber through a quartz tube of 12 mm inner diameter. A seven-turn rf coil was mounted on the quartz tube to produce high-density plasma. The Si substrate was located in a downstream region. Diamond formation was carried out with varying mixture ratio of source gases at total pressures of 70–140 mTorr. Diamond crystals exhibiting a well-defined1332 cm−1diamond Raman peak can be formed usingCH3OH/H2/H2Omixtures at total pressures below 140 mTorr.