Nucleation and Initial Growth Stages of Chemical Vapor Deposition (CVD) Diamond

Abstract

Nucleation of diamond on non‐diamond virgin substrates is characterized by low nucleation densities and long incubation times. Various methods have been developed to enhance nucleation densities and reduce the duration of incubation. This report describes a number of different but related studies of diamond nucleation on silicon and chemically modified silicon surfaces. The effect on the initial stages of deposition of mechanical abrasion with slurries and in‐situ sample biasing are especially discussed. Substrate abrasion with diamond results in the embeddying of diamond debris into its surface. Destructive ion implantation into this diamond debris is found to prevent subsequent diamond growth, therefore leading to the conclusion that the diamond debris serves as growth centers. Abrasion of the substrate with mixed metal/diamond slurries is reported to further enhance nucleation relative solely to diamond abrasion. It is suggested that during the chemical vapor deposition (CVD) process some metals alter the composition of the gas phase above the growing surface. Also, the role of surface reactions is emphasized. We also introduce the dc‐glow discharge process as a novel, in situ surface pretreatment method for the formation of a precursor for diamond nucleation. Our results show that the promotion of diamond growth by this method is primarily due to formation of nano‐size diamond particles during the pretreatment process. It is suggested that, to some extent, graphitic carbon with a high degree of defects may serve as a diamond nucleation center as well.

Improved adhesion of polycrystalline diamond films on copper/carbon composite surfaces due to in situ formation of mechanical gripping sites

“…Diamond depositions have been conducted on several non-diamond substrates showing mainly two issues, low growth rate and poor adhesion. While the growth rate is related to nucleation density [4], the adhesion is compromised because of the internal residual stresses in the deposited diamond films [5]. These stresses are divided in two parts, thermal stress which is provoked by the coefficient of thermal expansion (CTE) mismatch between the diamond film and the substrate, and intrinsic stress which is related to the grain boundary formation and impurity content during diamond growth.…”