Selective growth of boron-doped polycrystalline diamond thin films

The synthesis of in situ selective growth of boron-doped and phosphorus-doped polycrystalline diamond thin films on silicon substrates is reported. A high-pressure microwave plasma-assisted CVD system is used to grow the films. The doping source for boron is a glassy matrix of B2O3, P2O5, and other oxides. The deposition rate is approximately 1 micron/hr. The resistivity of as-grown doped polycrystalline diamond films is decreased by three to four orders of magnitude from undoped thin films. The resistivity of undoped diamond thin films is increased by three to four orders of magnitude when they are annealed in nitrogen ambient at 425 C for a few hours, whereas no significant change is observed in the case of boron-doped diamond thin films. Characterization of the as-grown doped films is performed by SEM, Raman spectroscopy, SIMS, XRD, and current-voltage measurements. The effect of annealing on sheet resistance is described.