Nanocrystalline diamond film grown by pulsed linear antenna microwave CVD

The growth of large area nanocrystalline diamond (NCD) films is of industrial interests because of their applications as tribological coatings and micromechanical actuators. To reduce thermal payloads, pulsed linear antenna plasma deposition (LAPD) has been developed to grow NCD at a lower average substrate temperature than continuous plasma deposition, but the relationship between pulse cycles and film microstructure is not well understood. Here, we investigated the pulsed LAPD growth of smooth nanocrystalline diamond with high hardness and low residual stress on 4-inch wafers, carried out at 500 degrees C substrate temperature using CH4/CO2/H2 gas mixtures. By alternating continuous and pulsed plasma, smooth film with a hardness of 38 GPa, modulus of 315 GPa and residual stress of -690 MPa was grown. TEM cross-section analysis of the interface provided insights into the film morphology as a function of pulsed deposition conditions. Our work shows that frequencymodulated plasma allows the growth of nanocrstalline diamond films with desirable attributes of smoothness, high mechanical strength and low residual stress.

Automated summary

The study successfully grew smooth nanocrystalline diamond films with high hardness and low residual stress at a lower average substrate temperature using pulsed linear antenna plasma deposition. TEM cross-section analysis provided insights into the film morphology as a function of pulsed deposition conditions. The research demonstrates that frequency-modulated plasma allows the growth of nanocrystalline diamond films with desirable attributes of smoothness, high mechanical strength and low residual stress.