Homogeneous and large-area diamond film formed using multi-filament chemical vapor deposition

Abstract

Diamond synthesis under metastable conditions by chemical vapor deposition (CVD) has been a subject of considerable interest in the past decade. Hot-filament chemical vapor deposition (HFCVD) has been extensively used to deposit diamond films. The advantages of this method are its simplicity, reproducibility, and potential for large-area applications. Coiled filaments, such as tungsten, tantalum, and rhenium wires, have been generally used in the HFCVD method. However, the distortion of these filaments makes it difficult in practice to secure homogeneous and large-area diamond films. To cope with filament deformation and obtain homogeneous deposition of diamond film over large areas, researchers have used straight wires to replace coiled wires as filaments. Growing diamond films of uniform thickness and high quality over large areas and at suitable growth rates also requires enhanced substrate temperature uniformity. A further issue is that contamination of diamond films by metallic impurities originating from the filament has been reported in some studies, but not in others. In the research reported here, the authors attempted to synthesize homogeneous, high-quality diamond film with a large area (70 mm x 70 mm) using a nine-filament diamond CVD process. The authors also examined the metallic impurities in diamond film grown using thismore » method.« less