| 摘要 |
A method of fabricating a polycrystalline CVD synthetic diamond material having an average thermal conductivity at room temperature through a thickness of the polycrystalline CVD synthetic diamond material of at least 2000 Wm-1K-1comprises: loading a refractory metal substrate into a CVD reactor; locating a refractory metal guard ring around a peripheral region of the refractory metal substrate, the refractory metal guard ring defining a gap between an edge of the refractory metal substrate and the refractory metal guard ring having a width 1.5 -5.0 mm; introducing microwaves into the reactor at a power such that the power density in terms of power per unit area of the refractory metal substrate is 2.5-4.5 Wmm-2; introducing process gas into the reactor wherein the gas comprises a nitrogen concentration of 600-1500 ppb calculated as molecular nitrogen N2, a carbon containing gas concentration of 1.5-3.0% by volume, and a hydrogen concentration of 92-98.5% by volume; controlling the average temperature of the refractory metal substrate to lie between 750-950oC and to maintain a temperature difference between an edge and a centre point on the refractory metal substrate of no more than 80oC; growing polycrystalline CVD synthetic diamond material to a thickness of at least 1.3 mm; and cooling the polycrystalline CVD synthetic diamond. |
