• Journal of IKEEE
• /
• v.26 no.1
• /
• pp.111-118
• /
• 2022

In this paper, we studied 4H-SiC CMOS that can be integrated with high-voltage SiC power devices. After designing the CMOS on a 4H-SiC substrate, we compared the electrical characteristics with the reliability of high temperature operation by TCAD simulation. In particular, it was confirmed that changing HfO₂ as the gate dielectric for reliable operation at high temperatures improves the thermal properties compared to SiO₂. By researching SiC CMOS devices, we can integrate high-power SiC power devices with SiC CMOS for excellent performance in terms of efficiency and cost of high-power systems.

• Korean Journal of Materials Research
• /
• v.19 no.2
• /
• pp.90-94
• /
• 2009

The development of low-k materials is essential for modern semiconductor processes to reduce the cross-talk, signal delay and capacitance between multiple layers. The effect of the $CH_4$ concentration on the formation of SiOC(-H) films and their dielectric characteristics were investigated. SiOC(-H) thin films were deposited on Si(100)/$SiO_2$/Ti/Pt substrates by plasma-enhanced chemical vapor deposition (PECVD) with $SiH_4$, $CO_2$ and $CH_4$ gas mixtures. After the deposition, the SiOC(-H) thin films were annealed in an Ar atmosphere using rapid thermal annealing (RTA) for 30min. The electrical properties of the SiOC(-H) films were then measured using an impedance analyzer. The dielectric constant decreased as the $CH_4$ concentration of low-k SiOC(-H) thin film increased. The decrease in the dielectric constant was explained in terms of the decrease of the ionic polarization due to the increase of the relative carbon content. The spectrum via Fourier transform infrared (FT-IR) spectroscopy showed a variety of bonding configurations, including Si-O-Si, H-Si-O, Si-$(CH_3)_2$, Si-$CH_3$ and $CH_x$ in the absorbance mode over the range from 650 to $4000\;cm^{-1}$. The results showed that dielectric properties with different $CH_4$ concentrations are closely related to the (Si-$CH_3$)/[(Si-$CH_3$)+(Si-O)] ratio.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.13 no.6
• /
• pp.290-296
• /
• 2003

The heteroepitaxial growth of crystalline 3C-SiC on 6H-SiC substrates using high purity silane ($SiH_4$) and prophane ($C_3H^8$) was carried out by thermal chemical vapor deposition, and growth characteristics were investigated in this study. In case that the flow ratio of C/Si and flow rate of $H_2$ were 4.0 and 5.0 slm, respectively, the growth rate of epilayers was about 1.8 $\mu$m/h at growth temperature of $1200^{\circ}C$. The Nomarski surface morphology, X-ray diffraction, Raman spectroscopy, and photoluninescence of grown epilayers were measured to investigate the crystallinity. In this study, the high quality of crystalline 3C-SiC heteropitaxial layers was observed at growth temperature of above $1150^{\circ}C$.

• Electrical & Electronic Materials
• /
• v.4 no.2
• /
• pp.123-131
• /
• 1991

SiH$_{4}$환원에 의한 selective CVD-W 공정에서 SiH$_{4}$ 유속의 W막 특성에 대한 효과를 조사하였다. 0.7$_{4}$/SW$_{2}$(=R)<0.9에서 .betha.-W이 나타나기 시작하여 SiH$_{4}$ 유속의 증가에 따라 .betha.-W의 함량은 게속 증가한다. W막의 표면 형태도 SiH$_{4}$유속의 증가에 따라 나뭇잎 모양(R<0.5), 흐릿하고 불안정한 모양(0.70.9에서는 주상의 결정립을 나타낸다. R.leq.0.7에서는 .alpha.-W만 존재하다가 0.7$_{4}$유속의 증가에 따라 증착속도와 W막의 정기저항이 증가한다. 특히, R.geq.0.9에서 전기저항이 급증한다. SiH$_{4}$유속의 증가에 따라 선택성이 악화되며 특히 1.1

• Korean Journal of Materials Research
• /
• v.8 no.6
• /
• pp.477-483
• /
• 1998

$SiC_{4}$$C_{3}$$H_{ 8}$$H_{2}$와 $C_{3}$$H_{8}$ $H_{2}$, $CH_{3}$$SiCI_{3}$$CH_{4}$$H_{2}$계를 사용하여 흑연기판 위에 SiC와 SiC/C FGM을 CVD법에 의해 코팅하였다. $SiCI_{4}$$C_{3}$$H_{8}$ $H_{2}$ 계에서 SiC 증착 시 바람직한 수소의 비는 10-30사이였고 결정 배향성은 입력가스의 탄소비에 따라 여러번의 대 반전이 일어났다. 성장조건을 {111} 배향성을 갖도록 조절하는 것이 FGM층간 접착상태를 증진시킬 수 있는 방법으로 판단되었다. $CH_{3}$$SiCI_{3}$C$_{3}$$H_{8}$ $H_{2}$ 계에서는 SiC와 C의 비율을 조절하기가 $SiCI_{4}$$C_{3}$$H_{8} $H_{2}$계를 사용했을 때 보다 용이하였고, FGM 단면 관찰에서 층간의 뚜렷한 경계를 발견할 수 없을 정도로 우수한 층간 접착상태를 보였다.

• Journal of the Korean Vacuum Society
• /
• v.8 no.1
• /
• pp.51-54
• /
• 1999

Hydrogenated amorphous silicon (a-Si:H) films are fabricated by Argon radical annealing (ArRA). The deposition rate of continuously deposited a-Si:H film is 1.9 $\AA$/s. As ArRA time are increased to 0.5 and 1 minute, the deposition rate are increased to 2.8 $\AA$/s and 3.3 $\\AA$/s. The deposition rate of a-si:H films with 2 and 3 minutes ArRA time are 3.3 $\AA$/s. As the ArRA time is increased, the optical band gap and the hydrogen contents in the a-Si:H films are increased and slightly decreased. The light-induced degradation of ArRA treated a-Si:H films are less than that of continuously deposited a-Si:H film. The dark conductivity and the conductivity activation energy ($E_a$) of continuously deposited a-Si:H film are decreased to 1/25 in room temperature and increased to 0.09eV By 1 hour light soaking, respectively. The dark conductivity and $E_a$ of ArRA treated a-Si:H film decreased to 1/3 in room temperature and increased to 0.03eV by 1 hour light soaking, respectively. We could improve the stability of a-Si:H films under the light soaking by ArRA technique and discussed the microscopic process of ArRA technique.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.66 no.2
• /
• pp.370-378
• /
• 2017

A fluid model of 2D axis-symmetry based on inductively coupled plasma (ICP) reactor using $N_2/NH_3/SiH_4$ gas mixture has been developed for hydrogenated silicon nitride ($SiN_x:H$) deposition. The model was comprised of 62 species (electron, neutral, ions, and excitation species), 218 chemical reactions, and 45 surface reactions. The pressure (10~40 mTorr) and gas mixture ratio ($N_2$ 80~96 %, $NH_3$ 2~10 %, $SiH_4$ 2~10 %) were considered simulation variables and the input power fixed at 1000 W. Different distributions of electron, ions, and molecules density were observed with pressure. Although ionization rate of $SiH_2{^+}$ is higher than $SiH_3{^+}$ by electron direct reaction with $SiH_4$, the number density of $SiH_3{^+}$ is higher than $SiH_2{^+}$ in over 30 mTorr. Also, number density of $NH^+$ and $NH_4{^+}$ dramatically increased by pressure increase because these species are dominantly generated by gas phase reactions. The change of gas mixture ratio not affected electron density and temperature. With $NH_3$ and $SiH_4$ gases ratio increased, $SiH_x$ and $NH_x$ (except $NH^+$ and $NH_4{^+}$) ions and molecules are linearly increased. Number density of amino-silane molecules ($SiH_x(NH_2)_y$) were detected higher in conditions of high $SiH_x$ and $NH_x$ molecules density.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2003.11a
• /
• pp.60-60
• /
• 2003

디자인 룰에 의해 Gate Length 가 100nm 이하로 줄어듦에 따라 Gate delay 감소와 Switch speed 향상을 위해 보다 더 큰 drive current 를 요구하게 되었다. 본 연구는 dirve current 를 증가시키기 위해 고안된 Strained Si substrate 를 만들기 위한 SiGe layer 성장에 관한 연구이다. SiGe layer를 성장시킬 때 SiH$_4$ gas와 GeH$_4$ gas를 furnace에 flow시켜 Chemical 반응에 의해 Si Substrate를 성장시키는 LPCVD(low pressure chemical vapor depositio)법을 사용하였고 SIMS와 nanospec을 이용하여 박막 두께 및 Ge concentration을 측정하였고, AFM으로 surface의 roughness를 측정하였다. 본 연구에서 우리는 10,20,30,40%의 Ge concentration을 갖는 10nm 이하의 SiGe layer를 얻기 위하여 l0nm 이하의 fixed 된 두께로 SiGe layer를 성장시킬 때 temperature, GeH$_4$ gas pre-flow, SiH$_4$ 와 GeH$_4$의 gas ratio를 변화시켜 성장시킨 후 Ge 의 concentration과 실제 형성된 두께를 측정하였고, SiGe의 mole fraction의 변화에 따른 surface의 roughness 를 측정하였다. 그 결과 10 nm의 두께에서 temperature, GeH$_4$ gas pre-flow, SiH$_4$ 와 GeH$_4$ 의 gas ratio의 변화와 Ge concentration 과의 의존성을 확인 할 수 있었고, SiGe 의 mole traction이 증가하였을 때 surfcace의 roughness 가 증가함을 알 수 있었다. 이 연구 결과는 strained Si 가 가지고 있는 strained Si 내에서 n-FET 와 P-FET사이의 불균형에 대한 해결과 좀 더 발전된 형태인 fully Depleted Strained Si 제작에 기여할 것으로 보인다.

• Asian Pacific Journal of Cancer Prevention
• /
• v.13 no.12
• /
• pp.5975-5979
• /
• 2012

Background: To investigate the influence of telomerase activity, apoptosis, radiosensitivity of cervical cancer after siRNA-mediated knockdown of telomerase RNA and evaluate in vivo growth with gene interference. Methods: We studied siRNA-targeting-telomerase RNA transfection into the Hela cell line. Expression of hTERC mRNA was detected by RT-PCR and telomerase activity was measured by the TRAP assay. Growth inhibition was determined by MTT assay and radiosensitivity of the cervical cancer cells was examined by colony formation assay. In addtion, effects of hTERC inhibition in vivo were studied by injection of siRNA-transfected Hela cells into nude mice. Results: The hTERC siRNA effectively downregulated the expression of hTERC mRNA and also reduced the telomerase activity to 30% of the untreated control vlaue. The viability of hTERC siRNA transfected Hela cells was reduced by 44.7% after transfection. After radiation treatment, the radiosensitivity of Hela cells with hTERC knockdown was increased. In vivo, the tumors developing from the hTERC siRNA-transfected cells were of reduced size, indicating that the hTERT siRNA also depressed the tumorigenic potential of the Hela cells. Conclusions: Our results supported the concept of siRNA-mediated inhibition of telomerase mRNA which could inhibit the expression of hTERC and telomerase activity. Furthermore, radiosensitivity was upregulated after knockdown the hTERC in vivo and in vitro.

• Applied Chemistry for Engineering
• /
• v.10 no.1
• /
• pp.98-104
• /
• 1999

In this work, we investigated hydrogen content, bond structure, and electrical properties of a-Si:H films prepared by ECR plasma CVD as a function of pressure. In general, the photo sensitivity of a-Si:H films prepared by CVD method decreases as the deposition rate increases, but the photo sensitivity of a-Si:H films prepared by ECR plasma deposition method increases as the deposition rate increases. In the same condition of microwave power, the ratio of $SiH_4/H_2$, and pressure, though film thickness increases linearly with deposition time and hydrogen content in the film is constant, photo conductivity can be decreased because $SiH_2$ bond is made more than SiH bond in the short reaction time. According to increase pressure in the chamber, SiH bond in the film increase and optical energy gap decrease. So, photo conductivity can be increased. But photo sensitivity decreased as dark conductivity increase. It must be grown in the condition of low pressure and hydrogen gas for taking the a-Si:H film of high quality.