• 한국전기전자재료학회논문지
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• 제37권1호
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• pp.101-105
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• 2024

4H-SiC power metal-oxide-semiconductor field effect transistors (MOSFETs) have been developed to achieve lower specific-on-resistance (R_on,sp), and the gate oxides have been thermally grown. The poor channel mobility resulting from the high interface trap density (D_it) at the SiO₂/4H-SiC interface significantly affects the higher switching loss of the power device. Therefore, the development of novel fabrication processes to enhance the quality of the SiO₂/4H-SiC interface is required. In this paper, NO post-oxidation annealing (POA) by using the conditions of N₂ diluted NO at a high temperature (1,300℃) is proposed to reduce the high interface trap density resulting from thermal oxidation. The NO POA is carried out in various NO ambient (0, 10, 50, and 100% NO mixed with 100, 90, 50, and 0% of high purity N₂ gas to achieve the optimized condition while maintaining a high temperature (1,300℃). To confirm the optimized condition of the NO POA, measuring capacitance-voltage (C-V) and current-voltage (I-V), and time-of-flight secondary-ion mass spectrometry (ToF-SIMS) are employed. It is confirmed that the POA condition of 50% NO at 1,300℃ facilitates the equilibrium state of both the oxidation and nitridation at the SiO₂/4H-SiC interface, thereby reducing the D_it.

• 한국세라믹학회지
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• 제48권5호
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• pp.384-389
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• 2011

Gas pressure sintering (GPS) of reaction bonded silicon nitride (RBSN) was performed using $Lu_2O_3-SiO_2$ additive and the properties were compared with those of specimens prepared using high purity $Si_3N_4$ powder. The relative density of RBSN and compacted $Si_3N_4$ powder were 68.9 and 47.1%, and total linear shrinkage after sintering at $1900^{\circ}C$ were 14.8 and 42.9%, respectively. High nitrogen partial pressure (5MPa) was required during sintering at $1900^{\circ}C$ in order to prevent the decomposition of the nitride and to promote the formation of SiC. The relative density and 4-point bending strength of RBSN and $Si_3N_4$ powder compact were 97.7%, 954MPa and 98.2%, 792MPa, respectively, after sintering at $1900^{\circ}C$. The sintered RBSN also showed high fracture toughness of 9.2MPam$^{1/2}$.

• Journal of Magnetics
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• 제15권3호
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• pp.132-137
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• 2010

Plasma etching of $SiO_2$ contact holes was statistically analyzed by a fractional factorial experimental design. The analysis revealed the dependence of the etch rate and DC self-bias voltage on the input factors of the magnetically enhanced reactive ion etching reactor, including gas pressure, magnetic field, and the gas flow rates of $CHF_3$, $CF_4$, and Ar. Empirical models of the DC self-bias voltage and etch rate were obtained. The DC self-bias voltage was found to be determined mainly by the operating pressure and the magnetic field, and the etch rate was related mainly to the pressure and the flow rates of Ar and $CHF_3$.

• Journal of Electrochemical Science and Technology
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• 제10권3호
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• pp.294-301
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• 2019

The quasi-solid-state hybrid electrolytes were synthesized by chemical cross-linking reaction of methacrylate-functionalized $SiO_2$ ($MA-SiO_2$) and tetra (ethylene glycol) diacrylate in aqueous electrolyte. A quasi-solid-state electrolyte synthesized by 6 wt.% $MA-SiO_2$ exhibited a high ionic conductivity of $177mS\;cm^{-1}$ at room temperature. The electrochemical $H_2$ sensor assembled with quasi-solid-state electrolyte showed relatively fast response and high sensitivity for hydrogen gas at ambient temperature, and exhibited better durability and stability than the liquid electrolyte-based sensor. The simple construction of the sensor and its sensing characteristics make the quasi-solid-state hydrogen sensor promising for practical application.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.1
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• pp.41-43
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• 2004

Dielectric thin films of $(Pb_{0.72}La_{0.28})Ti_{0.93}O_3$ were deposited on $Pt(111)/Ti/SiO_2/Si$ substrates in situ by pulsed laser deposition(PLD) and annealed with different gases which are forming gas and oxygen gas, respectively. The diffusion of hydrogen into the ferroelectric film was caused by annealing process and resulted in the destruction of polarization. The dielectric properties of forming gas annealed PLT thin films, which are dielectric constant, ferroelectric characteristic, and leakage current characteristics, were degraded

• 한국세라믹학회지
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• 제40권12호
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• pp.1165-1169
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• 2003

이중 이온빔 스퍼터링(Dual ion-beam sputtering)을 사용하여 보조이온건의 Ar/O$_2$가스유량 변화에 따라 Si-(III) 기판과 glass에 Ta$_2$O$_{5}$ 박막을 증착시켰다. 보조 이온총의 산소 가스량의 비가 감소함에 따라서 증착되는 Ta$_2$O$_{5}$ 박막의 성장속도는 감소하였으며, 굴절률은 $O_2$ 가스의 양이 0∼12sccm인 범위에서 2.09(at 1550nm)로 일정한 값을 나타내었다. Ar:O$_2$가 3: 12인 조건에서 화학양론 조성인 Ta$_2$O$_{5}$를 형성하였으며, 표면 거칠기도 가장 작은 값을 나타내었다.나타내었다.

• 한국세라믹학회지
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• 제38권11호
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• pp.1037-1041
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• 2001

저온(32$0^{\circ}C$)에서 SiH$_4$와 $N_2$O 가스의 혼합을 통해 플라즈마화학기상증착(PECVD)법을 이용하여 실리카 광도파로의 클래딩막으로 사용되는 SiO$_2$후막을 제조하였다. 증착변수가 SiO$_2$후막의 특성에 미치는 영향을 살펴보기 위해 $N_2$O/SiH$_4$flow ratio와 RF power에 변화를 주었다. $N_2$O/SiH$_4$ flow ratio가 감소함에 따라 증착속도는 2.9 $mu extrm{m}$/h), 굴절률은 thermal oxide의 굴절률(n=1.46)에 근접하였다.

• Journal of Information Display
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• 제2권1호
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• pp.38-42
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• 2001

Thin films of $In_2O_3-SnO_2$(ITO), $SnO_2$, and $SiO_2$ were prepared on the PET substrate by DC magnetron roll sputtering. 135 nm thick ITO film on $SiO_2$/PET substrate has sheet resistance as low as 55 ${\Omega}/square$ and transmittance as high as 85%. $H_2O$gas permeation through the film was 0.35 g/$m^2$ in a day. These properties are enough on optical film for the plastic LCD substrate or touch panel. Both refractive index and sheet resistance of ITO was found to be very sensitive to $O_2$ flow rate. Oxygen flow conditions have been optimized from 4 to 5 SCCM at $10^{-3}$torr. It is also shown that both thickness of $SnO_2$ and refractive index of $SiO_2$ decrease as $O_2$ flow rate increases.

• 한국결정성장학회지
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• 제8권2호
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• pp.233-239
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• 1998

화학기상증착법을 이용하여 tetramethylsilane(TMS)과 hexamethyldisilane(HMDS)으로부터 SiC층을 증착시켰다. 반응관 내의 압력은 1torr를 유지시켰으며, $H_2$ 가스를 사용하여 precursor를 반응로내로 수송하였고 $1200^{\circ}C$의 반응온도로 SiC 증착이 이루어졌다. 기판은 tantalum으로 masking한 Si-wafer와 platinum, molybdenum으로 masking한 MgO 단결정을 사용하였다. 금속층(Ta, Pt, Mo)에서의 SiC 증착 양상과 Si, MgO 위에서의 SiC 증착 양상을 비교함으로써 SiC 증착의 선택성을 관찰하였다. 증착층의 주된 상은 X-선 회절분석에 의해 $\beta-SiC$로 확인되었다. 또한 전자현미경 분석을 통해 각 층에서의 증착 양상의 차이를 조사하였다.

• 한국재료학회지
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• 제7권2호
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• pp.102-106
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• 1997

박막형 접촉연소식을 포함한 마이크로 가스센서에서 membrane은 Si식각시 식각정지용으로서 또 센서 소자를 지지하는 층으로서 응력이 없어야 하며 이는 응력이 membrane파괴의 주 원인으로 작용하기 때문이다. 이에 따라 본 연구에서는 증착조건이 low pressure chemical vapor deposition(LPCVD)법과 sputtering법으로 제작된 $SiN_{x}$과 $SiN_{x}/SiO_{x}/(NON)$막의 응력고 굴절율 변화에 미치는 효과에 대한 실험을 행하였다. LPCVD의 경우 단일막인 $SiN_{x}$의 압축응력 및 굴절율을 나타내었다. Sputtering의 경우 $SiN_{x}$는 공정압력이 1mtorr에서 30torr까지 증가할수록 인가전력밀도가 $2.74W/cm^2$에서 $1.10W/cm^2$으로 감소할수록 응력값은 압축에서 인장으로 전환되었으며 본 실험에서 응력이 가장 낮게 나온 시편의경우 압축응력으로 $1.2{\times}10^{9}dyne/cm^2$가 공정압력 10mtorr, 인가전력밀도 $1.37W/cm^2$에서 얻어졌다. 굴절율은 공정압력이 1motorr에서 30motorr까지 증가할수혹 인가전력밀도가 $2.74W/cm^2$에서 $1.10W/cm^2$으로 감소할수록 감소하여 2.05에서 1.89의 변화를 보였다. LPCVD와 sputtering으로 증착된 막들은 모두 온도가 증가함에 따라 응력이 감소하였으며 온도감소시 소성적인 특성을 나타내었다.