THE CVD OF DIAMOND

A basic reaction in the CVD of diamond is based on the decomposition of a hydrocarbon, such as methane, as follows ... 

The following 11 criteria are generally accepted guidelines for the CVD of diamond films. 

III. The Uses of High-Sensitivity White-Light Absorption Spectroscopy in the CVD of Diamond Films... 

As stated in the introduction, high-sensitivity white-light absorption spectroscopy has been used more extensively in studying the gas-phase composition during the CVD of diamond films than in other applications of CVD. In this section we review the use of high-sensitivity white-light absorption for the measiuement of n for the various free radicals and molecules present in the CVD of diamond under different conditions. 

High-sensitivity white-light absorption spectroscopy was used in the detection of CH3 and C2H2 in the CVD of diamond by Childs et al. (1992) in a hot-filament... 

The principles of thermodynamics and idnetics of CVD as they apply to the deposition of graphite were reviewed in Ch. 7, Sec. 2.0.( 1 These considerations are valid for the CVD of diamond as well. 

In the microwave-assisted or hot-filament-assisted CVD of diamond, methane and hydrogen gases (CH ca 1—5% and 95—99%) are used. In... 

Figure 15 shows the variation of diamond deposition rates by various activated CVD techniques as well as the HP—HT technique (165). It can be seen that the highest growth rate of activated CVD diamond synthesis is stiU an order of magnitude lower than the HP—HT technique. However, CVD has the potential to become an alternative for diamond growth ia view of the significantly lower cost of activated CVD equipmeat and lower miming and maintenance costs. 

Most CVD-diamond processes require a plasma (see Ch. 5. Sec. 9). Two types of plasma are currently used for the deposition of diamond microwave plasma (non-isothermal) and arc plasma (isothermal). 

Whereas a microwave plasma is most commonly used for the PE-CVD of diamond films, an ECR is the only plasma that is used for diamond deposition below 1 Torr [27-29]. Although Bozeman et al. [30] reported diamond deposition at 4 Torr with the use of a planar ICP, there have been a few reports that describe the synthesis of diamond by low-pressure ICP. Okada et al. [31-33] first reported the synthesis of nanocrystalline diamond particles in a low-pressure CH4/CO/H2 ICP, followed by Teii and Yoshida [34], with the same gas-phase chemistry. 

At temperatures around 600°C and extremely low pressures, methane will decompose and deposit a thin film of carbon, in the form of diamond, on a surface. The process, known as chemical vapour deposition, or CVD, can be used to coat a wide variety of surfaces. The hardness of this diamond film can be used for applications that require non-scratch surfaces such as cookware, eyeglasses, and razor blades. 

Conditions for the deposition of diamond using microwave plasma CVD... 

Under conditions similar to those used for the synthesis of diamond layers, only layers with a small amount of c-BN can be deposited. A lot of publications can be found about the deposition of c-BN with CVD methods, reporting different parameters that are necessary for the growth of c-BN. 

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