• 한국표면공학회지
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• 제32권3호
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• pp.303-306
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• 1999

On the effect of substrate bias at first stage of diamond synthesis at lower substrate temperature(approximately 673K) using microwave plasma CVD and effect of reaction gas system for the bias enhanced nucleation were studied. The reaction gas was mixture of methane and hydrogen or carbon monoxide and hydrogen. The nucleation density of applied bias -150V using $CH_4-H_2$ reaction gas system, significantly higher than that of $C-H_2$ reaction gas system. When the $CH_4-H_2$ reaction was used, nucleation density was increased because of existence of SiC as a interface for diamond nucleation. By use of this negative bias effect for fabrication of CVD diamond film using two-step diamond growth without pre-treatment, fabrication of the diamond film consist of diamond grains $0.2\mu\textrm{m}$ in diameter was demonstrated

• The Korean Journal of Ceramics
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• 제3권3호
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• pp.155-158
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• 1997

Highly oriented diamond films were deposited on a (100) silicon substrate by bias enhanced nucleation technique. Both plan-view and cross-section TEM were applied to study the nucleation and growth mechanism of diamond grains. Randomly oriented polycrystalline diamond grains with internal microtwins were observed at the nucleation stage while defect free regions were retained at the growth stage and were apparently related with the epitaxy of diamond films. From our experimental results, the nucleation and texture formation mechanism of diamond films is discussed.

• The Korean Journal of Ceramics
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• 제2권4호
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• pp.197-202
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• 1996

The highly oriented diamond particles were deposited on the mirror-polished (100) silicon substrates in the bell-jar type microwave plasma deposition system using a three-step process consisting if carburization, bias-enhanced nucleation and growth. By adjusting the geometry of the substrate and substrate holder, very dense disc-shaped plasma was formed over the substrate when the bias voltage was below -200V. Almsot perfectly oriented diamond films were obtained only in this dense disc-shaped plasma. From the results of the optical emission spectra of the dense disc-shaped plasma, it was found that the concentrations of atomic hydrogen and hydrocarbon radical were increased with negative bias voltage. It was also found that the highly oriented diamonds were deposited in the region, where the intensity ratios of carbonaceous species to atomic hydrogen are saturated.

• 한국진공학회지
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• 제7권2호
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• pp.94-103
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• 1998

HFCVD(Hot Filament Chemical Vapor Deposition)방법을 이용한 다이아몬드의 핵 생성과 성장에 있어서, 인가한 직류 bias를 변수로 하여 핵생성 밀도와 증착율의 변화를 조 사하였다. 반응압력 20torr, 메탄농도 1.0%, Filament 온도 $2100^{\circ}C$ 그리고 Substrate 온도 $980^{\circ}C$에서 증착 단계를 핵생성기와 성장기로 구분하고 각 단계마다 bias의 방향과 크기를 다르게 인가하면서 다이아몬드 박막을 증착시켰다. Negative bias는 핵생성기에는 핵생성을 촉진시키지만 성장기에도 계속 인가하면 결정입자의 지속적인 성장을 방해하고 결정 구조를 비다이아몬드 성분으로 변화시키는 작용을 하여 박막의 morphology에 좋지 않은 영향을 주 었다. Positive bias는 핵생성기와 성장기에서 모두 $CH_4$의 분해를 촉진시킨 결과 증착율의 향상을 가져왔다. 따라서 다이아몬드 박막의 증착시 핵생성기에서는 negative bias를 인가하 고 성장기에는 positive bias를 인가하는 것이 핵생성 밀도와 증착율의 향상에 효과적인 것 으로 조사되었다.

• 한국결정성장학회지
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• 제12권6호
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• pp.311-316
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• 2002

2-step 증착법과 Bias-Enhanced Nucleation(BEN)법을 이용해 다결정 Ni 기판에 고품질의 다이아몬드 박막 합성을 연구하였다. $810^{\circ}C$에서 1시간 증착하여 soot충을 형성시킨 후 기판온도를 soot층의 형성이 억제되는 온도인 $925^{\circ}C$로 올려 5시간 증착하는 2-step법을 통해 고품질의 다이아몬드를 합성할 수 있었다. 또한, $925^{\circ}C$에서 -220V의 bias를 10분 동안 기판에 인가한 후 2시간 동안 증착하는 BEN법을 이용해 양질의 다이아몬드를 합성할 수 있었다. $925^{\circ}C$에서 bias 처리를 하지 않은 경우에는 10시간 동안 증착을 시도한 후에도 다이아몬드가 생성되지 않았다.

• 한국세라믹학회지
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• 제34권6호
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• pp.636-644
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• 1997

The effect of various processing parameters, in particular the substrate and filament temperature, on the nucleation of diamond has been studied for the hot filament CVD process with a negative bias on the substrate. As far as the substrate temperature was maintained around the critical temperature of 73$0^{\circ}C$, the nucleation of diamond increased with increasing filament temperature. The maximum nucleation density of ~ 2$\times$109/$\textrm{cm}^2$ was obtained under the condition of filament temperature of 230$0^{\circ}C$, substrate temperature of 75$0^{\circ}C$, bias voltage of 300V, methane concentration of 20%, and deposition time of 2 hours. This nucleation density is about the same as those obtained in previous investigations. For fixed substrate temperatures, the nucleation density varies up to about 103 times depending on experimental conditions. This result is different from that of Reinke, et al. When the substrate temperature was above 80$0^{\circ}C$, a silkworm~shaped carbon phase was co-deposited with hemispherical microcrystalline diamond, and its amount increased with increasing substrate temperature. The Raman spectrum of the silkworm-shaped carbon was the same as that of graphitic soot. The silkworm-shaped carbon was etched and disappeared under the same as that of graphitic soot. The silkworm-shaped carbon was etched and disappeared under the deposition condition of diamond, implying that it did not affect the nucleation of diamond.

• 한국재료학회:학술대회논문집
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• 한국재료학회 1997년도 한국재료학회 춘계학술발표회
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• pp.112-112
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• 1997

• 반도체디스플레이기술학회지
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• 제3권3호
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• pp.45-50
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• 2004

Highly oriented diamond (HOD) films in polycrystalline can be grown on the (100) silicon substrate by microwave plasma CVD. Bias enhanced nucleation (BEN) method was adopted for highly oriented diamond deposition with high nucleation density and uniformity. The substrate was biased up to -250[Vdc] and bias time required for forming a diamond film was varied up to 25 minutes. Diamond was deposited by using $\textrm{CH}_4$/CO and $H_2$ mixture gases by microwave plasma CVD. Nucleation density and degree of orientation of the diamond films were studied by SEM. Thermal conductivity of the diamond films was ∼5.27[W/cm.K] measured by $3\omega$ method.

• 한국표면공학회지
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• 제46권1호
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• pp.29-35
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• 2013

The effect of DC bias on the growth of nanocrystalline diamond films on silicon substrate by microwave plasma chemical vapor deposition has been studied varying the substrate temperature (400, 500, 600, and $700^{\circ}C$), deposition time (0.5, 1, and 2h), and bias voltage (-50, -100, -150, and -200 V) at the microwave power of 1.2 kW, working pressure of 110 torr, and gas ratio of Ar/1%$CH_4$. In the case of low negative bias voltages (-50 and -100 V), the diamond particles were observed to grow to thin film slower than the case without bias. Applying the moderate DC bias is believed to induce the bombardment of energetic carbon and argon ions on the substrate to result in etching the surfaces of growing diamond particles or film. In the case of higher negative voltages (-150 and -200 V), the growth rate of diamond film increased with the increasing DC bias. Applying the higher DC bias increased the number of nucleation sites, and, subsequently, enhanced the film growth rate. Under the -150 V bias, the height (h) of diamond films exhibited an $h=k{\sqrt{t}}$ relationship with deposition time (t), where the growth rate constant (k) showed an Arrhenius relationship with the activation energy of 7.19 kcal/mol. The rate determining step is believed to be the surface diffusion of activated carbon species, but the more subtle theoretical treatment is required for the more precise interpretation.

• 한국결정성장학회지
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• 제4권1호
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• pp.92-99
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• 1994

마이크로웨이브 화학 기상 중착법을 이용하여 n 형 Si(100) 기팡위에 다이아몬드 박막을 증착하였다. 다이아몬드의 핵생성 밀도를 향상시키기 위하여 Si 기판을 다이아몬드 분말로 전처리 하거나 negative bias를 인가하여 다이아몬드 박막을 증착하였다. 전처리한 기판에서는 다이아몬드의 순수도가 전체압력이 증가함에 따라 (20~150 Torr)향상되었으며 bias 인가시에는$CH_4$ 농도와 전체압력에 따라 다이아몬드의 생성유무가 결정되었다.플라즈마의 이온에 의해 가판위에 생성되는 전류를 $CH_4$ 농도, bias 전압, 그리고 전체압력에 따라 측정하였으며 그 결과를 다이아몬드 박막의 생성 조건과 관련시켜 검토 하였다.