• Journal of the Korean Vacuum Society
• /
• v.18 no.4
• /
• pp.288-295
• /
• 2009

We report the etch characteristics of GaAs and AlGaAs in the diffusion pump-based capacitively coupled $BCl_3$ plasma. Process variables were chamber pressure ($50{\sim}180$ mTorr), CCP power ($50{\sim}200\;W$) and $BCl_3$ gas flow rate ($2.5{\sim}10$ sccm). Surface profilometry was used for etch rate and surface roughness measurement after etching. Scanning electron microscopy was used to analyze the etched sidewall and surface morphology. Optical emission spectroscopy was used in order to characterize the emission peaks of the $BCl_3$ plasma during etching. We have achieved $0.25{\mu}m$/min of GaAs etch rate with only 5 sccm $BCl_3$ flow rate when the chamber pressure was in the range of 50{\sim}130 mTorr. The etch rates of AlGaAs were a little lower than those of GaAs at the conditions. However, the etch rates of GaAs and AlGaAs decreased significantly when the chamber pressure increased to 180 mTorr. GaAs and AlGaAs were not etched with 50 W CCP power. With $100{\sim}200\;W$ CCP power, etch rates of the materials increased over $0.3{\mu}m$/min. It was found that the etch rates of GaAs and AlGaAs were not always proportional to the increase of CCP power. We also found the interesting result that AlGaAs did not etched at 2.5 sccm $BCl_3$ flow rate at 75 mTorr and 100 W CCP power even though it was etched fast like GaAs with more $BCl_3$ gas flow rates. By contrast, GaAs was etched at ${{\sim}}0.3{\mu}m$/min at the 2.5 sccm $BCl_3$ flow rate condition. A broad molecular peak was noticed in the range of $500{\sim}700\;mm$ wavelength during the $BCl_3$ plasma etching. SEM photos showed that 10 sccm $BCl_3$ plama produced more undercutting on GaAs sidewall than 5 sccm $BCl_3$ plasma.

• Development and Reproduction
• /
• v.15 no.2
• /
• pp.113-120
• /
• 2011

BCL-2 family essential proteins to play a pivotal role to perform in apoptosis signaling pathways and essential proteins for the regulation of cell death. BCL2L10 protein is a member of BCL-2 family and it regulates both anti-apoptotic and pro-apoptotic function of specific tissue or cell line. BCL2L10 of function and expression is not reported in ovary cell lines. In this study we reported that BCL2L10 were significant expression of KGN cell line. Ectopic expression of BCL2L10 induced cell death, and its cells killing effect was blocked by pan-caspase inhibitor of the Z-VAD-fmk. Ectopic expression of BCL2L10 protein led to the activation of caspase 9 and caspase 3, suggesting apoptotic cell death, and confocal microscopic analyses showed that BCL2L10 was partially localized in mitochondria. Thus, we provide a novel function of BCL2L10 in KGN cells, which was involved in the intrinsic cell death pathway.

• Proceedings of the KIEE Conference
• /
• 2004.11a
• /
• pp.72-74
• /
• 2004

In this study, we used a inductively coupled plasma (ICP) source for etching $Al_2O_3$ thin films because of its high plasma density, low process pressure and easy control bias power. $Al_2O_3$ thin films were etched using $Cl_2/BCl_3$, $N_2/Cl_2/BCl_3$, and Ar/$Cl_2/BCl_3$ plasma. The experiments were carried out measuring the etch rates and the selectivities of $Al_2O_3$ to $SiO_2$ as a function of gas mixing ratio, rf power, and chamber pressure. When $Cl_2$ 50% was added to $Cl_2/BCl_3$ plasma, the etch rate of the $Al_2O_3$ films was 118 nm/min. We also investigated the effect of gas addition. In case of $N_2$ addition, the etch rate of the $Al_2O_3$ films decreased while $N_2$ was added into $Cl_2/BCl_3$ plasma. However, the etch rate increased slightly as Ar added into $Cl_2/BCl_3$ plasma, and then further increase of Ar decreased the etch rate. The maximum etch rate was 130 nm/min at Ar 20% in $Cl_2/BCl_3$ plasma, and the highest etch selectivity was 0.81 in $N_2$ 20% in $Cl_2/BCl_3$ plasma. And, we obtained the results that the etch rate increases as rf power increases and chamber pressure decreases. The characteristics of the plasmas were estimated using optical emission spectroscopy (OES).

• Proceedings of the KIEE Conference
• /
• 2006.10a
• /
• pp.117-118
• /
• 2006

In this work, we investigated etching characteristics of $HfO_2$ thin film and Si using inductive coupled plasma (ICP) system. The ion energy distribution functions in an inductively coupled plasma was analyzed by quadrupole mass spectrometer with an electrostatic ion energy analyzer. The maximum etch rate of $HfO_2$ is 85.5 nm/min at a $BCl_3/(BCl_3+Ar)$ of 20% and decreased with further addition of $BCl_3$ gas. From the QMS measurements, the most dominant positive ion energy distributions (IEDs) showed a maximum at 20 % of $BCl_3$. These tendency was very similar to the etch characteristics. This result agreed with the universal energy dependency of ion enhanced chemical etching yields. And the maximum selectivity of $HfO_2$ over Si is 3.05 at a O2 addition of 2 sccm into the $BCl_3/(BCl_3+ Ar)$ of 20% plasma.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.37 no.11
• /
• pp.18-24
• /
• 2000

(Ba,Sr)$TiO_3$ thin films have attracted great interest as new dielectric materials of capacitors for ultra-large-scale integrated dynamic random access memories (ULSI-DRAMs) such as 1 Gbit or 4 Gbit. In this study, inductively coupled $BCl_3/Cl_2/Ar$ plasmas was used to etch (Ba,Sr)$TiO_3$ thin films. RF power/dc bias voltage=600 W/-250 V and chamber pressure was 10 mTorr. The $Cl_2/(Cl_2+Ar)$ was fixed at 0.2 the (Ba,Sr)$TiO_3$ thin films were etched adding $BCl_3$. The highest (Ba,Sr)$TiO_3$ etch rate is $480{\AA}/min$ at 10 % $BCl_3$ to $Cl_2/Ar$. The change of Cl, B radical density measured by optical emission spectroscopy(OES) as a function of $BCl_3$ percentage in $Cl_2/Ar$. The highest Cl radical density was shown at the addition of 10% $BCl_3$ to $Cl_2/Ar$. To study on the surface reaction of (Ba, Sr)$TiO_3$ thin films was investigated by XPS analysis. Ion bombardment etching is necessary to break Ba-O bond and to remove $BaCl_2$. There is a little chemical reaction between Sr and Cl, but Sr is removed by physical sputtering. There is a chemical reaction between Ti and Cl, and $TiCl_4$ is removed with ease. The cross-sectional of (Ba,Sr)$TiO_3$ thin film was investigated by scanning electron microscopy (SEM), the etch slope is about 65~70$^{\circ}$.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2003.03a
• /
• pp.62-62
• /
• 2003

고밀도 유도결합 플라즈마(high density inductively coupled plasma) 식각은 GaAs 이종접합 양극성 트랜지스터(HBTs)와 고속전자 이동도 트랜지스터(HEMTs)와 같은 GaAs 기반 반도체의 정교한 패턴을 형성하는데 더욱 많이 이용되고 있다 본 연구는 고밀도 플라즈마 소스(source)인 평판형(planar) 고밀도 유도결합 플라즈마 식각장치를 이용하여 $BCl_3$ 와 $BCl_3/Ar$ 가스에 따른 GaAs 식각결과를 비교 분석하였다. 공정변수는 ICP 소스 파워를 0-500W, RIE 척(chuck) 파워를 0-150W, 공정압력을 0-15 mTorr 이었다. 그리고 가스 유량은 20sccm(standard cubic centimeter per minute)으로 고정시킨 상태에서 Ar 첨가 비율에 따른 GaAs의 식각결과를 관찰하였다. 공정 결과는 식각률(etch rate), GaAs 대 PR의 선택도(selectivity), 표면 거칠기(roughness)와 식각후 표면에 남아 있는 잔류 가스등을 분석하였다. 20 $BCl_3$ 플라즈마를 이용한 GaAs 식각률 보다 Ar이 첨가된 (20-x) $BC1_3/x Ar$ 플라즈마의 식각률이 더 우수하다는 것을 알 수 있었다. 식각률 증가는 Ar 가스의 첨가로 인한 GaAs 반도체와 Ar 플라즈마의 충돌로 나타난 결과로 예측된다. $BCl_3$ 와 $BC1_3/Ar$ 플라즈마에 노출된 GaAs 반도체 모두 표면이 평탄하였고 수직 측벽도 또한 우수하였다. 그리고 표면에 잔류하는 성분은 Ga와 As 이외에 $Cl_2$ 계열의 불순물이 거의 발견되지 않아 매우 깨끗함을 확인하였다. 이번 발표에서는 $BCl_3$ 와 $BCl_3/Ar$ 플라즈마를 이용한 GaAs의 건식식각 비교에 대해 상세하게 보고 할 것이다.

• Tuberculosis and Respiratory Diseases
• /
• v.46 no.1
• /
• pp.36-43
• /
• 1999

Background : Tumor growth is the net result of intrinsic proliferation and escape from active cell death. bcl-2 is a member of a new category of oncogenes that is not involved in influencing cell proliferation but is involved in regulating cell death(apoptosis). Based on this information, it seems to be reasonable to expect that there may be clinical prognostic significance of bcl-2 expression in non-small cell lung cancer. But its prognostic significance is not established. Methods: To investigate the role of bcl-2 in lung cancer, we performed immunohistochemical stain of bcl-2 on 57 biopsy specimens from resected primary non-small cell lung cancer. Thereafter, flow cytometric cell cycle analysis was done. And we analyzed the correlation between bcl-2 expression, clinical parameters, S-, $G_1$-phase fraction and survival. Results: bcl-2 were detected in 43.8% of total 57 patients(according to histology, squamous cancer 47%, adenocarcinoma 32%, according to TNM stage, I 28.6%, II 52.3%, III 45.5%. both differences were insignificant). By using the flow cytometric analysis, mean S-phase fraction of bcl-2(+) and (-) group were 14.1($\pm7.8$)%, 24.7($\pm10.5$)% (p<0.005), mean $G_1$-phase fraction of bcl-2(+) and bcl-2(-) group were 75.5($\pm10.8$)%, 65.5($\pm11.4$)%(p<0.05). 2yr, 3yr and 5yr survival and median survival time of bcl-2(+) group were 65%, 54%, 41%, 53 months, and those of bcl-2(-) group were 71%, 52%, 46%, 37 months. (p>0.05, Kaplan-Meier, log rank) Conclusion: bcl-2 was detected in 43.8% of primary non-small cell lung cancer. The S-phase fraction of bcl-2(+) group was less than bcl-2(-) group, and G1-phase fraction of bcl-2(+) group was more than bcl-2(-) group. But, expression of bcl-2 could not be a prognostic factor.

• Radiation Oncology Journal
• /
• v.20 no.3
• /
• pp.246-252
• /
• 2002

Purpose : It has been recognized that interaction of the Fas : Fas ligand plays an important role in radiation-induced apoptosis. The purpose of this study was to investigate the role of Fas mutation in radiation-induced apoptosis in vivo. Materials and Method : Mice with mutations in Fas, $MRL/Mpj-Fas^{Ipr}$, and its normal control, MRL/Mpj, were used in this study. Eight-week old male mice were given whole body radiation. After irradiation, the mice were killed and their spleens were collected at different time intervals. Tissue samples were stained with hematoxylin-eosin and the numbers of apoptotic cells were scored. Regulating molecules of apoptosis including p53, Bcl-2, Bax, $Bcl-X_L,\;and\;Bcl-X_S$ were also analyzed by Western blotting. Results : At 25 Gy irradiation, the level of apoptosis reached the peak value at 8 hr after radiation and recovered to the normal value at 24 hr after radiation in MRL/Mpj mice. In contrast, the peak apoptosis level appeared at 4 hr after radiation in $MRL/Mpj-Fas^{Ipr}$. At 8 hr after radiation, the levels of apoptosis in MRL/Mpj mice and $MRL/Mpj-Fas^{Ipr}$ mice were $52.3{\pm}7.8\%\;and\;8.0{\pm}8.6\%$, respectively (p<0.05). The expression of apoptosis regulating molecules, p53, $Bcl-X_L\;and\;Bcl-X_S$, increased in MRL/Mpj mice in response to radiation; p53 with a peak level of 3-fold at 8 h, $Bcl-X_L$ with a peak level of 3.3-fold at 12 h, and $Bcl-X_S$ with a peak level of 3-fold at 12 h after 25 Gy radiation. Bcl-2 and Bax did not show significant change in MRL/Mpj mice. However in $MRL/Mpj-Fas^{Ipr}$ mice, the expression levels of p53, Bcl-2, Bax, $BCl-X_L\;and\;BCl-X_S$ showed no significant change. Conclusion : The level of radiation-induced apoptosis was lower in Fas mutated mice, Ipr, than in control mice. This seemed to be related to the lack of radiation-induced p53 activation in the Ipr mice. This result suggests that Fas plays an important role in radiation-induced apoptosis in vivo.

• Proceedings of the KIEE Conference
• /
• 2005.11a
• /
• pp.54-56
• /
• 2005

QMS를 이용하여 chlorine based 유도결합 플라즈마 내 이온의 거동에 대한 분석을 하였다. 플라즈마 진단 가스로는 AT 가스에 $BCl_3$을 첨가하였으며 공정 압력을 변화하며 플라즈마 특성 변화를 분석하였다. 가스 혼합비에 따른 이온의 상대적인 밀도 변화에서 소량의 Ar가스의 첨가는 $BCl_3$ 가스의 이온화를 도와 $Cl^+$ 이온이 증가하는 현상을 보이며 Ar과 $BCl_3$의 이온화 에너지의 차이로 인해 $BCl_3$ 가스의 첨가비가 적을 수록, RF Power가 증가하며, 공정 압력이 낮올 수록 이중 피크 구조의 이온 에너지 분포를 확인 할 수 있었으며 이는 이온이 접지 전극에의 도달 시간과 평균 플라즈마 전위의 변화 때문이라고 사료된다.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.55 no.4
• /
• pp.204-208
• /
• 2006

In this study, we investigated the ion energy distributions in a chlorine based inductively coupled plasma by quadrupole mass spectrometer with an electrostatic ion energy analyzer. Ion energy distributions are presented for various plasma parameters such as $BCl_3/Ar$ gas mixing ratio, RF power, and process pressure. As the $BCl_3/Ar$ gas mixing ratio and process pressure decreases, and RF power increases, the saddle-shaped structures is enhanced. The reason is that there are ionized energy difference between $BCl_3$ and Ar, change of plasma potential, alteration of mean free path. and variety of ion collision in the sheath.