Uniformity of nucleation

Elowever, as stated in Section 10.2,2 [222], a secondary plasma could be generated in the center of the substrate between the main plasma ball and the substrate holder as well as the outer rim of the substrate holder. The substrate holder has a complicated shape and was precoated with diamond film, and the 3-inch Si(lOO) substrate had been carburized prior to the BEN treatment. As a result, the diamond nucleation occurred both in the center and the peripheral of the substrate. Thus, the position of the secondary plasma depends on the geometry of the reactor chamber. 

Milne et al. [228] synthesized HOD films using the two-step process. The carburization step of Si substrate was not essential, but effective in reducing the period of the BEN step. The (lOO)-oriented diamond area was formed in a region of a concentric ring that was 25% of the deposited area of a 4-inch wafer. 

Temperature (K) Substrate Substrate-holder Electrode 813 Silicon (100) square of 10 X 10 mm Molybdenum Graphite 0 = 30 mm 1073 1113 1073 

P = 20-30 Torr. It seems, however, that the degree of azimuthal alignment of (100) faces in the diamond film grown for 3 h is significantly lower than that made by using the standard conditions [329]. 

In Ref. [332], the BEN treatment was carried out using the conditions hsted in Table H.3. After the treatment for 30 min, the diamond deposition was not uniform. 

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