Low surface temperature synthesis and characterization of diamond thin films

摘要

Polycrystalline diamond films are deposited on n-type Si(100) and n-type SiC(6H) substrates at low surface deposition temperatures of 370-530 deg C using a microwave plasma enhanced chemical vapor deposition (MPECVD) system. The surface temperature during deposition is monitored by an IR pyrometer capable of measuting temperature between 250 and 600 deg C in a microwave environment. The lower deposition temperature is achieved by using an especially designed cooling stage. The influence of the deposition conditions on the growth rate and structure of the diamond film is investigated. A very high growth rate up to 1.3 mu m/h on SiC substrate at 530 deg C surface temperature is attributed to an optimized Ar-rich Ar/H_2/CH_4 gas composition, deposition pressure, and microwave power. The structure and microstructure of the films are characterized by X-ray diffraction, scanning electron microscopy, and Raman spectroscopy. A detailed stress analysis of the deposited diamond films of grain sizes between 2 and 7 mu m showed a net tensile residual stress and predominantly sp~3-bonded carbon in the deposited films.