• Title/Summary/Keyword: Bias enhanced nucleation

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EFFECT OF SUBSTRATE BIAS ON THE DIAMOND GROWTH USING MICROWAVE PLASMA CVD

  • Sakamoto, Yukihiro;Takaya, Matsufumi
    • Journal of the Korean institute of surface engineering
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    • v.32 no.3
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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

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Three-dimensional TEM Characterization of Highly Oriented Diamond Films on a (100) Silicon Substrate

  • Seung Joon Jeon;Arun Kymar Chawla;Young Joon Baik;Changmo Sung
    • The Korean Journal of Ceramics
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    • v.3 no.3
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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.

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Heteroepitaxial Growth of Diamond Films Synthesized by Microwave Plasma Enhanced Chemical Vapor Deposition

  • Kim, Yoon-Kee;Lee, Jai-Young
    • The Korean Journal of Ceramics
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    • v.2 no.4
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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.

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Bias effect for diamond films deposited by HFCVD method (HFCVD 방법을 이용한 다이아몬드 박막 증착에서의 Bias 효과)

  • 권민철;박홍준;최병구
    • Journal of the Korean Vacuum Society
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    • v.7 no.2
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    • pp.94-103
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    • 1998
  • We investigated a bias effect for diamond films deposited by a HFCVD(Hot Filament Chemical Vapor Deposition) method using a methane-hydrogen gas mixture. During deposition total chamber pressure, methane concentration, filament temperature and substrate temperature was 20 torr, 1.0%, $2100^{\circ}C$ and $980^{\circ}C$ respectively. Also DC bias was applied during both the nucleation stage and the growth stage systematically. We found that negative bias enhanced the nucleation density at the nucleation stage, but it made a bad influence on the morpholohy of films at the growth stage. Positive bias enhanced the growth rate and resulted in a good morpholohy of films. Therefore we concluded that it was effective to apply the negative bias during the nucleation stage and then to switch into the positive bias during the growth stage in the fabrication of diamond films.

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Diamond thin film deposition on Ni in microwave plasma CVD (Microwave plasma CVD에서 Ni 기판에 다이아몬드 박막 증착)

  • Kim, Jin-Kon;Ryu, Su-Chak;Cho, Hyun
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.12 no.6
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    • pp.311-316
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    • 2002
  • Two different approaches, namely two-step deposition process and Bias-Enhanced Nucleation (BEN) technique have been examined for deposition of high quality diamond thin film on polycrystalline Ni which has low chemical activity with the carbon neutrals provided from the $CH_4/H_2$mixtures. A two-step deposition process, consisted of pre-deposition of soot layer at lower temperatures and subsequent deposition at higher temperature condition, has been developed to deposit diamond layer directly on Ni substrate. Diamond particles were observed after deposition step at $925^{\circ}C$ for 5 hours and those particles seem to be nucleated from the soot layer pre-deposited at lower temperatures ($810^{\circ}C$). Diamond particles of a substantial size were found on Ni substrate after biasing -220 V for 10 minutes and subsequent deposition for 2 hours while no diamond particles were observed under the conditions without applied bias.

Bias-enhanced Nucleation of Diamond in Hot Filament CVD (열필라멘트 CVD에서 전압 인가에 의한 다이아몬드의 핵생성 촉진)

  • Choi, Kyoon;Kang, Suk-Joong L.;Hwang, Nong-M.
    • Journal of the Korean Ceramic Society
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    • v.34 no.6
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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.

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Growth of Highly Oriented Diamond Films by Microwave Plasma Chemical Vapor Deposition (마이크로파 플라즈마 화학기상증착법에 의한 HOD 박막 성장)

  • 이광만;최치규
    • Journal of the Semiconductor & Display Technology
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    • v.3 no.3
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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.

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Effect of DC Bias on the Growth of Nanocrystalline Diamond Films by Microwave Plasma CVD (마이크로웨이브 플라즈마 CVD에 의한 나노결정질 다이아몬드 박막 성장 시 DC 바이어스 효과)

  • Kim, In-Sup;Kang, Chan Hyoung
    • Journal of the Korean institute of surface engineering
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    • v.46 no.1
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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.

Deposition of diamond thin film by MPECVD method (마이크로웨이브 화학 기상 증착법을 이용한 다이아몬드 박막의 증착)

  • Sung Hoon Kim;Young Soo Park;Jo-Won Lee
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.4 no.1
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    • pp.92-99
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    • 1994
  • Diamond thin film was deposited on n type (100) Si substrate by MPECVD(Microwave plasma Enhanced Chemical Vapor Deposition). For the increase in nucleation density of diamond, Si substrate was pretreated by diamond powder or negative bias voltage was applied to the substrate during the initial deposition. In the case of retreated Si substrate, the diamond thin film quality was enhanced with increasing the total pressure in the range of 20~150 Torr. For the negative bias voltage, the formation condition of the diamond was seriously affected by $CH_4$ concentration and total pressure. The formation condition will be discussed with electrical current of substrate generated by plasma ions which depend on $CH_4$concentration, bias voltage, and total pressure.

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