Low-Temperature Diamond Deposition

Abstract

The success of diamond growth from the vapor phase has been an important innovation in expanding the area of application of this fascinating material. The chemical vapor deposition (CVD) method has enabled us to obtain crystalline diamond at easily controllable temperatures such as 800–900°C. For actual use of CVD-diamond films in various application areas, however, the growth temperature is still too high. Many efforts have been devoted to lowering the growth temperature to extend the limitations of material for the substrate at such a high temperature. Such high temperatures of the substrate during growth induce stress due to the difference in the expansion rates. Low-temperature growth is an essential technique required for practical application areas, especially for electronics applications. For electronics applications, the substrate temperature is limited not only by the melting point of the material but also by the diffusion of impurities. While a silicon substrate itself is still stable at the conventional CVD growth temperature, silicon devices will easily lose their structures of impurity profiles, heterojunctions, and metal interfaces. One of the objectives of low-temperature CVD of diamond is the temperature at which electronics devices can be active; for instance, from 200°C to 400°C. Another objective is diamond coating on low melting point materials, especially on organic polymers.