Diamond films were deposited on the pretreated silicon or on the pretreated glass substrate in a microwave plasma enhanced chemical vapor deposition ͑MPECVD͒ system. We can increase the diamond nucleation density by the cyclic process, irrespective of the substrate kinds and deposition conditions. Using the cyclic process, we can certainly enhance the selective deposition of diamond film on glass substrate. The cyclic process is the in situ method carried out by the cyclic modulation of the CH 4 source gas flow rate during the initial deposition stage. Surface morphologies and diamond qualities of the films have been investigated. Based on these results, we discuss the cause for the enhancement of the selectivity of diamond film deposition on glass substrate by the cyclic process.Recently, the study for the application of synthetic diamond films for electronic devices has been more and more noted because of the unique properties of diamond, such as high bandgap energy, high thermal conductivity, high carrier mobility, etc. 1,2 One of the most difficult barriers for the application of synthetic diamond films to electronic devices is the patterning of diamond film. Up to the present, many attempts have been tried to pattern diamond film. 3,4 Conventional technique for fabricating the patterns of semiconductor materials is the etching technique. However, in the case of diamond film, the etching technique should be difficult due to the hardness and chemical inertness of diamond. Therefore, the selective deposition of diamond film has been regarded as a promising method to replace the etching technique.For the selective deposition of diamond film, the pretreatment technique by using diamond powders or pastes has been introduced. 5-8 This technique usually used the masking process which the optimal materials, such as yttria-stabilized zirconia ͑YSZ͒, 5 SiO 2 , 6 a-Si:H, 7,8 overlay on the untreated area of the substrate for preventing the diamond nucleation. Although these processes can promote the selectivity of diamond film deposition, they still require the enhancement of the selectivity. For the enhancement of the selective deposition of diamond film on glass substrate, increasing the diamond nucleation on the pretreated area with simultaneously suppressing the diamond nucleation on the untreated area is the primary technology.Enhancement of the diamond nucleation density can be carried out by either the ex situ process like a pretreatment technique 9,10 or the in situ process like a BEN technique. 11 Compared with the ex situ process, the in situ process has the advantage for the further enhancement of the diamond nucleation density, because the in situ technique can be applied on the ex situ treated substrate, consequently obtaining more enhanced nucleation density. Up to the present, unfortunately, the reports on the in situ process for the enhancement of the diamond nucleation density are few except a BEN technique. 11 This work presents a new in situ process, what we call the cyclic process, for the enhancemen...
