• Transactions on Electrical and Electronic Materials
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• 제14권4호
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• pp.203-207
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• 2013

P-type Si wafers were dipped in HF solution. The minority carrier lifetime (lifetime) increased after HF treatment due to the hydrogen termination effect. To investigate the film passivation effect, PECVD was used to deposit $SiN_x$ on both HF-treated and untreated wafers. $SiN_x$ generally helped to improve the lifetime. A thermal process at $850^{\circ}C$ reduced the lifetime of all wafers because of the dehydrogenation at high temperature. However, the HF-treated wafers showed better lifetime than untreated wafers. PERCs both passivated and not passivated by HF treatment were fabricated on the rear side, and their characteristics were measured. The short-circuit current density and the open-circuit voltage were improved due to the effectively increased lifetime by HF treatment.

• 한국응용과학기술학회지
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• 제36권3호
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• pp.876-884
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• 2019

We investigated the effect of moderate- and high-intensity resistance training on hippocampal neurotrophic factors and peripheral CCL11 levels in high-fat diet (HFD)-induced obese mice. C57/black male mice received a 4 weeks diet of normal (control, CON; n = 9) or a high-fat diet (HF; n = 27) to induce obesity. Thereafter, the HF group was subdivided equally into the HF, HF + moderate-intensity exercise (HFME), and HF + high-intensity exercise (HFHE) groups (n = 9, respectively), and mice were subjected to ladder-climbing exercise for 8 weeks. The hippocampal brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) levels were significantly lower in the HF group than in the CON group (p < 0.05). In addition, in the HFME and HFHE groups were significantly higher than in the HF group (p < 0.05). The peripheral CCL11 levels were significantly higher in the HF group than in the CON group (p < 0.05). In addition, in the HFME and HFHE groups were significantly lower than in the HF group (p < 0.05). However, there was no significant difference according to the exercise intensity among the groups. Collectively, these results suggest that obesity can induce down-regulation of neurotrophic factors and inhibition of neurogenesis. In contrast, regardless of exercise intensity, resistance training may have a positive effect on improving brain function by inducing increased expression of neurotrophic factors.

• JSTS:Journal of Semiconductor Technology and Science
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• 제1권2호
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• pp.95-102
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• 2001

Hafnium oxide thin films for gate dielectric were deposited at $300^{\circ}C$ on p-type Si (100) substrates by plasma enhanced chemical vapor deposition (PECVD) and annealed in $O_2$ and $N_2$ ambient at various temperatures. The effect of hydrogen treatment in 4% $H_2$ at $350^{\circ}C$ for 30 min on the electrical properties of $HfO_2$for gate dielectric was investigated. The flat-band voltage shifts of $HfO_2$capacitors annealed in $O_2$ambient are larger than those in $N_2$ambient because samples annealed in high oxygen partial pressure produces the effective negative charges in films. The oxygen loss in $HfO_2$films was expected in forming gas annealed samples and decreased the excessive oxygen contents in films as-deposited and annealed in $O_2$ or $N_2$ambient. The CET of films after hydrogen forming gas anneal almost did not vary compared with that before hydrogen gas anneal. Hysteresis of $HfO_2$films abruptly decreased by hydrogen forming gas anneal because hysteresis in C-V characteristics depends on the bulk effect rather than $HfO_2$/Si interface. The lower trap densities of films annealed in $O_2$ambient than those in $N_2$were due to the composition of interfacial layer becoming closer to $SiO_2$with increasing oxygen partial pressure. Hydrogen forming gas anneal at $350^{\circ}C$ for samples annealed at various temperatures in $O_2$and $N_2$ambient plays critical role in decreasing interface trap densities at the Si/$SiO_2$ interface. However, effect of forming gas anneal was almost disappeared for samples annealed at high temperature (about $800^{\circ}C$) in $O_2$ or $N_2$ambient.

• Nutritional Sciences
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• 제7권2호
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• pp.70-75
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• 2004

The objective of this study was to examine diet-induced changes in the expression of UCP2 mRNA in the liver and UCP3 mRNA in the skeletal muscle of mice fed a high-sucrose or high-fat diet. Male ICR mice, aged 4 weeks, were divided into three dietary groups and fed control (N) or modified AIN-76 high-sucrose (US) or high-fat (HF) diets for 12 weeks. The serum total cholesterol (TC) and LDL-cholesterol concentrations of the HF group were significantly higher than those of the N and HS groups. The hepatic TC and triglyceride contents of the HS and HF groups were also significantly higher than those of the N group. The HS diet group had higher serum leptin and insulin levels compared to those of the HF group. Hepatic UCP2 mRNA expression was significantly higher in the HS group than in the N group, but the level in the HF group did not differ from that of the N group. Muscular UCP3 mRNA level was significantly higher in the HF group and especially in the HS group than in N the group. We observed that two gene (UCP2, 3) levels exhibited a similar tendency. These results suggest that UCPs mRNA levels and energy expenditure may be altered or controlled by various dietary patterns. Further research is needed to elucidate the effects of diet on the regulation of many obesity-related genes.

• JSTS:Journal of Semiconductor Technology and Science
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• 제5권2호
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• pp.107-112
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• 2005

We present an AlGaN/GaN metal-insulator-semiconductor-heterostructure field effect transistor (MIS-HFET) with an $Al_2O_3-HfO_2$ laminated high-k dielectric, deposited by plasma enhanced atomic layer deposition (PEALD). Based on capacitance-voltage measurements, the dielectric constant of the deposited $Al_2O_3-HfO_2$ laminated layer was estimated to be as high as 15. The fabricated MIS-HFET with a gate length of 102 m exhibited a maximum drain current of 500 mA/mm and maximum tr-ansconductance of 125 mS/mm. The gate leakage current was at least 4 orders of magnitude lower than that of the reference HFET. The pulsed current-voltage curve revealed that the $Al_2O_3-HfO_2$ laminated dielectric effectively passivated the surface of the device.

• 생명과학회지
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• 제31권5호
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• pp.488-495
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• 2021

본 연구에서는 부평초가 고지방과 고콜레스테롤 식이로 산화손상이 유도된 비만 쥐에서 간 조직의 항산화 효소활성 및 활성산소의 제거에 미치는 영향을 보고자 하였다. 실험군은 정상 식이군(N 군), 고지방과 고콜레스테롤 식이군(HF 군), 고지방과 고콜레스테롤 식이에 부평초를 5% 첨가한 군(SPA 군), 고지방과 고콜레스테롤 식이에 부평초를 10% 첨가한 군(SPB 군)으로 나누었다. 식이 및 식수는 자유섭취하게 하였으며 4주간 사육한 후 희생시켰다. 먼저 체중, 식이량 변화 및 간 무게의 변화를 측정한 결과, 체중에서는 N 군에 비해 HF 군에서 유의적으로 증가하였으나, 그 외의 군간의 차이는 나타내지 않았으며, 식이량에서 또한 각각의 실험군에서 유의적인 차이가 관찰되지 않았다. 간 무게 에서는 N 군에 비해 HF, SPA 및 SPB 군에서 유의적으로 증가하였으나, 그 외의 실험군 간의 유의적인 차이는 나타내지 않았다. 간 조직에서 주요 항산화 효소의 활성도에서 SOD는 N 군에 비해 HF군에서 감소되었으나 부평초를 공급한 SPA 및 SPB 군에서는 유의적으로 증가되었다. Gpx 및 catalase 또한 고지방과 고콜레스테롤 섭취로 인해 감소된 활성이 부평초의 공급으로 유의적으로 증가되었다. Superoxide radical 함량을 mitochondria 및 microsome에서 측정한 결과 N 군에 비해 HF 군에서 유의적인 증가를 나타내었으나 부평초 공급한 모든 군에서 유의하게 감소되었다. 특히 microsome에서는 군간의 유의한 차이도 나타났다. 간 조직의 H₂O₂의 함량은 mitochondria에서는 SPA 및 SPB군 모두에서 유의적인 감소로 정상군 수준을 나타내었고, cytosol 에서는 10% 부평초 공급군에서 유의적으로 감소되었다. 간 조직의 microsome 및 mitochondria에서의 carbonyl value는 N 군에 비해 HF 군에서 유의적으로 증가 되었으나 부평초의 공급으로 유의적으로 감소하였고 특히 군간의 유의한 차이도 나타났다. TBARS를 간 조직에서 관찰 한 결과 N 군에 비해 HF 군에서 유의적으로 증가하였으나 SPA 및 SPB 모든 군에서 유의한 감소를 나타내었다. 이러한 결과로 미루어 부평초에 함유된 여러 생리활성 물질들은 고지방과 고콜레스테롤 식이로 인해 산화적으로 손상된 간 조직의 재생에 작용하여 항산화 효과에 탁월하게 작용하였음이 사료된다.

• 한국환경농학회지
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• 제29권2호
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• pp.146-151
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• 2010

In order to improve T-N and T-P removal in HF (horizontal flow)-HF hybrid constructed wetlands by natural purification method for treating the hydroponic wastewater in greenhouses, the efficiency of water treatment as affected by the injection method of hydroponic wastewater, the addition of special filter media, the particle size of filter media, and the injection ratio of hydroponic wastewater in $1^{st}$ HF and $2^{nd}$ HF beds were investigated in small-scale HF-HF hydroponic wastewater treatment apparatus. Removal rate of T-P in the water in HF-HF hydroponic wastewater treatment apparatus with calcite as affected by addition method of special filter media was higher than that in HF-HF hydroponic wastewater treatment apparatus with other filter media. Removal rate of BOD, COD, SS, T-N and T-P in the water in mixed filter media with calcite were 86, 84, 87, 50 and 97%, respectively. Removals of pollutants except for T-P in the water were slightly different. Therefore, it should be considered that the removal rate of T-P was good for calcite in HF-HF hydroponic wastewater treatment apparatus. To improve T-N and T-P removal, the optimum particle size of filter media was 1.2 mm, and the optimum injection ratio ($1^{st}$ HF bed : $2^{nd}$ HF bed) of hydroponic wastewater was 60:40.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.158-159
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• 2007

반도체 소자의 공정에 있어서 device scaling으로 인한 게이트 산화막 대체 유전체 (high-k)의 공정 개발 확보 방안 필요하다. 본 논문에서는 $Cl_2$/Ar 유도 결합 플라즈마를 이용하여 $HfO_2$ 박막을 식각하였다. $Cl_2$(80 %)/Ar(20 %)의 가스비, 600 W의 RF 전력, -150 V의 직류 바이어스 전압, 20 sccm의 총 가스유랑, 15 mTorr의 압력에서 15.4 nm/min의 최대 식각률을 얻을 수 있었다. 식각 된 $HfO_2$ 박막 표면을 XPS 분석한 결과 Hf와 O는 Cl 라디칼과 반응을 하여 높은 휘발성을 보이지만 Hf-O의 안정된 결합으로 인하여 이온에 의한 스퍼터링 효과에 의해서 식각된다.

• 반도체디스플레이기술학회지
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• 제14권3호
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• pp.7-11
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• 2015

In order to protect the patterned mask from contamination during lithography process, pellicle has become a critical component for Extreme Ultraviolet (EUV) lithography technology. According to EUV pellicle requirements, the pellicle should have high EUV transmittance and robust mechanical property. In this study, silicon nitride, which is well-known for its remarkable mechanical property, was used as a pellicle membrane material to achieve high EUV transmittance. Since long silicon wet etching process time aggravates notching effect causing stress concentration on the edge or corner of etched structure, the remaining membrane is prone to fracture at the end of etch process. To overcome this notching effect and attain high transmittance, we began preparing a rather thick (200 nm) $SiN_x$ membrane which can be stably manufactured and was thinned into 43 nm thickness with HF wet etching process. The measured EUV transmittance shows similar values to the simulated result. Therefore, the result shows possibilities of HF thinning processes for $SiN_x$ EUV pellicle fabrication.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2012년도 춘계학술발표대회
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• pp.82.1-82.1
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• 2012

란타늄 산화물 ($La_2O_3$) 박막은 하프늄 산화물 ($HfO_2$) 박막보다 높은 유전 상수와 높은 밴드 오프셋으로 인해 dynamic random access memory(DRAM)에서 유전체 재료로써 연구되어 왔다. 그리고 Lanthanum이 도핑된 HfO2이 더 높은 유전 상수와 낮은 누설 전류 밀도를 갖는 다는 사실이 이전에 보고 된 바 있다. 본 연구에서 우리는 ALD를 이용하여, TiN 하부 전극 위에 $La_2O_3$의 위치를 달리하는 $La_2O_3/HfO_2$의 나노 층상조직 구조(두께 10 nm)를 금속 - 절연체 - 금속 (MIM) 구조로 제작 하였다. ALD는 좋은 comformality와 넓은 지역 균일성을 가지며, 원자수준의 두께를 조절할 수 있다는 장점을 갖고 있다. 또한, 다양한 화학 물질들을 이용한 복합적 계층구조를 만들 수 있는 점과 $HfO_2$ 및 $La_2O_3$ 계층의 수직 위치를 정확하게 조절할 수 있는 점으로 본 연구에 적합한 증착 방법이다. HfO2 속에 $La_2O_3$ 층을 깊이에 따라 삽입함으로써 $HfO_2$ 계층에 La 도핑의 효과와 더불어 TiN 하부 전극 위의 $La_2O_3$과 $HfO_2$의 차이점을 확인 하였다. $HfO_2$은 $250^{\circ}C$에서 TDMAH와 물을 사용하여, $La_2O_3$은 동일한 온도에서 $La(iPrCp)_3$와 물을 사용하여 제작되었다. 화학적 구성 및 binding 구조는 X선 광전자 분광법 (XPS)을 통해 분석하였다. 전기적 특성(유전 상수 및 누설 전류)은 Capacitance-Voltage (CV)와 Current-Voltage (IV) 측정으로 확인하였다. 결과적으로, $La_2O_3$ 또는 $HfO_2$을 한 종류만 사용한 절연층의 전기적 특성보다, $La_2O_3/HfO_2$의 나노 층상조직 구조가 더 나은 특성 (누설 전류 밀도 : $5.5{\times}10^{-7}\;A/cm^2$ @-1MV/cm, EOT : 14.6)을 갖는다는 것을 확인했고, 더불어 $La_2O_3$의 흡습 성질로 인한 화학 구조와 전기적 특성의 일부 차이를 확인하였다. 본 연구에서는 $HfO_2$ 속에 $La_2O_3$층이 TiN 하부 전극 바로 위에 위치할 때, 즉, 공기 중에 노출되지 않은 $La_2O_3/HfO_2$ 구조에서 가장 좋은 특성의 MIM capacitor를 얻을 수 있었다.