Analyses of Diamond Nucleation Processes on Carbonized Substrates

Abstract

The formation of carbonized interface layers is a spontaneous stage in the nucleation process of the chemical vapor deposition (CVD) of diamond onto substrates, however, the relationship between the carbonization and nucleation stages has not been well understood to date. This paper will discuss diamond nucleation mechanisms in relation to the carbonization of silicon substrates. For this purpose the silicon substrates are first carbonized using direct resistive heating. Then, diamonds are deposited on the substrates using a hot-filament CVD (HF-CVD) method. The experimental results reveal that when no ion effects exist, the solid-phase carbon reaches the same thermal equilibrium state as in the gas-phase during diamond deposition, and that the formation of the carbonized interface layers has no immediate relationship to diamond nucleation.

Ellipsometric monitoring of an oriented diamond nucleation process in bias-enhanced chemical vapor deposition

“…10 Real-time ellipsometry is a powerful method for the precise and accurate analysis of thin film structures and growth processes, and already has been applied to the processes of diamond film syntheses without BEN. [11][12][13][14][15] It has been shown that single-wavelength ellipsometry has a fast response and sensitive measurements in the early stages of diamond film growth: 11,12,14,15 the time evolution of film thickness has been evaluated and diamond nucleation processes have been analyzed. BEN has already been applied to a hot-filament chemical vapor deposition ͑HF-CVD͒ by other research groups; 16,17 however the effect of bias application in the HF-CVD of diamond has not been clarified.…”

“…19 Through diffusion, microindentions, i.e., voids, are created at the top of a silicon substrate. 15 Then the optically equivalent thickness for the first 2 min is due to a surface layer mainly including weakly bonded carbon like sp 2 one, sp 3 carbon, silicon, voids, and Si-C. The abrupt interruption of the thickness increase arises from the etching of the surface layer, especially weakly bonded carbon, by ions: the ion energy exceeds the threshold energy for sputter etching, which is generally several tens of eV.…”

“…During this incubation stage, weakly bonded carbons are selectively removed, while surviving sp 3 carbons form diamond nuclei. Many more carbon atoms are implanted into a substrate in the BEN process than for the solid-gas phase equilibrium in the process without the bias, 15 competing with the removal by etching. Thus it is speculated that the accelerated elimination of weak C-C bonds and the faster formation of sp 3 C-C bonds may result in high density and oriented growth of diamond particles.…”

Manufacture and Development of Nanostructured Diamond Tools

“…However, such abrasion methods damage the surface in a poorly defined manner. Thus, more controlled methods of nucleation such as biasing prior to CVD are becoming increasingly common [11,12] and can even enable heteroepitaxial growth of diamond films [13,14]. The gas-phase environment during deposition also affects the quality and morphology of the resulting diamond films.…”