Economic Assessment of CVD Diamond Synthesis Technologies

Abstract

Chemical Vapor Deposition (CVD) synthesis of diamond was discovered at almost the same time as the commercialization of the High Pressure - High Temperature (HPHT) synthesis of diamond grit. However, it took two decades to show feasibility of growing pure CVD diamond at practical rates. From about 1980 to the present, CVD diamond science and technology has undergone an explosive period of investigation, leading to the development of a number of CVD diamond techniques, including H-Atom-Plasma and Chemical Methods in the H-C, H-C-O and H-C-F systems. Because these CVD diamond technologies are either developmental or only recently in production, there are still numerous uncertainties in the eventual manufacturing costs attainable with CVD. To estimate CVD diamond manufacturing costs, and to compare them with those of commercial HPHT diamond synthesis, we employ a computer based Technical Cost Modeling (TCM) approach which has the flexibility to structure and evaluate model factories with a variety of unit processes representing the different CVD diamond synthesis techniques. A generic approach is first presented to calculate the cost of CVD diamond coatings, which allows future update of cost estimates by incorporating advances in equipment and plant size, process technology, and yield and deposition rate. The general case also provides a basis for assessing factors which influence the cost of depositing CVD diamond powder, or grit. Sensitivity analysis is then applied to the Microwave and Filament CVD methods to understand the dependence of CVD diamond costs upon growth rate, layer thickness, yield, and production volume. The polycrystalline CVD diamond X-ray window is an example of a high systems value commercial product already successful at small scale of manufacture. CVD diamond optical coatings and electronic components are potential specialty products which possess the capability of becoming commercially viable at low production volumes. At high volume manufacture, Microwave and Filament CVD diamond technologies appear economical for large area deposition of thin polycrystalline coatings for use in cutting tool inserts, at add-on costs below $150/carat. With advances in technology, thick diamond coatings for cutting tool inserts and thermal management components could ultimately become available at add-on-costs below $5/carat. Low process gas-to-diamond yield and high energy usage are the chief factors that limit the cost competitiveness of CVD diamond powder with HPHT diamond grit.