Yugos method

Since the BEN technique was found by Yugo et al. [3], numerous works have been done on BEN. The establishment of the HOD film growth technique was one of the most important motivations for the BEN studies. Even so, there are still controversy over fundamental issues among researchers the first is how diamond nuclei are formed by BEN, and the second is whether an interfacial layer exists, or an interfacial layer is necessary to grow HOD films. 

A cross-sectional TEM observation was also undertaken for a BEN-treated specimen under conditions of Fb = —60 V, c = 2%CH4/H2, Ts = 850 C, and P = ISTorr for lOmin [207]. These are nearly consistent with the HOD film growth conditions, as seen in Table H.3. No carburization process of the Si substrate was done. These BEN conditions are rather milder than other works. As a result. 

The distribution of SiC interlayer over a 76-mm Si(lll) wafer was examined after a 30-min BEN treatment at Kb = —125 V, followed by diamond growth (MPCVD) using c= 1.5%CH4/H2 for 2h. The thickness of SiC layer was markedly different between z- and x-directions, as observed by FT-IR [212], 

The average kinetic energy of positive ions was estimated as follows assuming that the mean-free-paths A of the ions are equal for CH4 and H, then A is expressed by  

In Ref [218], Kawarada et al. studied the polarity effects in BEN on the nucleation density using a NIRIM-type reactor, a Mo substrate holder, and Si(l 11) substrates under conditions of P = 0.2, 2, and 15Torr, c = 2, 10, and 40%CH4/H2, and Kb was between —100 and -flOOV. After the BEN treatment, diamond CVD was done for 3 h under conditions of c = 0.5%CH4/H2, P = 30 Torr, and = 950 °C to evaluate the nucleation density. Interestingly, it was found that  

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Since the method of BEN was first found by Yugo et al. [3], works of his group till date is first reviewed in the following. The reactor used was a NIRIM-type, as shown in Figure 3.1, where a negative DC bias of Kh = —lOOV was applied to an as received Si substrate with a resistivity of 1-5 - cm and placed on a molybdenum... 

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