• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.147-147
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• 2010

태양전지의 효율 향상을 위해 웨이퍼 표면에 반사방지막 코팅을 위한 패시베이션 물질들에 대한 연구가 활발히 진행 되고 있다. 이 과정에서 널리 사용하는 ARC 물질로 SiNx 박막이 있다. SiNx 박막은 PECVD 법으로 저온에서 실리콘 기판 위에 증착 가능한 장점이 있다. 플라즈마 분위기 가스로 아르곤 또는 질소 사용하며 SiNx 박막의 광학적, 전기적인 특성은 화학적 조성비에 의해 결정되며 증착온도 가변에 박막의 특성이 변화하며 이를 이용하여 태양전지의 효율을 향상 시킬 수 있다. 본 연구에서는 SiNx 박막을 형성하는데 질소 가스 분위기에서 PECVD를 이용하여 증착하고 그 특성을 분석하였다. 박막은 0.8 Torr의 압력에서 $150^{\circ}C\;{\sim}\;450^{\circ}C$의 기판온도로 증착되었으며 이때의 RF power은 100W ~ 300W로 가변 되었다. 증착된 박막은 1.94 에서 2.23의 폭넓은 굴절률 값을 가지고 있었다. $SiH^4/NH_3$ 가스 비의 증가에 따라 박막 두께와 굴절률이 감소함을 확인할 수 있었다.증착된 SiNx 박막의 소수반송자 수명 측정 결과 굴절률 2.23인 박막의 경우 약 87 us의 수명을 나타냈으며, 굴절률이 1.94로 줄어듦에 따라 소수 반송자 수명 역시 79 us로 감소하였다. SiNx 박막은 n-rich 보다 Si-rich 인 경우 effective 반송자 수명을 증가시켜 표면 재결합 속도를 줄이는데 유용함을 확인하였다. 또한 증착온도가 증가할수록, RF power가 증가 할수록 소수 반송자 수명 역시 증가하였다. 반사도의 경우 $SiH_4$의 비율이 증가할수록 반사도가 감소함을 확인 하였으며, 증착온도 증가에 따라, RF power 증가에 따라 반사도가 감소하였다. 결과적으로 $450^{\circ}C$의 기판온도와 300W의 RF power에서 증착된 SiNx 박막의 경우 가장 우수한 전기적, 광학적 특성을 보여주었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.339-342
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• 1998

Ferroelectric L $a_2$ $Ti_2$ $O_{7}$(LTO) thin films were prepared by chemical solution deposition processes. Acetylacetone was used as chelating agent and nitric acid was added in the stock solution to control hydrolysis and condensation reaction rate. The LTO thin films were spin-coated on Pt/Ti/ $SiO_2$/(100)Si and Pt/Zr $O_2$/ $SiO_2$/(100)Si substrates. After multiple coating, dried thin films were heat-treated for decomposition of residual organics and crystallization. The role of acetylacetone in Ti iso-propoxide stabilization by possibly substituting $O^{i}$Pr ligand was studied by H-NMR. B site-rich impurity phase, i.e. L $a_4$ $Ti_{9}$ $O_{24}$, was found after annealing, where its appearance was dependent on process temperature indicating the possible reaction with substrate. Dielectric and other relevant electrical properties were measured and the results were compared between modified sol-gel and MOD processes.s.s.

• Journal of Oral Medicine and Pain
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• v.1 no.1
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• pp.8-13
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• 1973

The authors had studied the oral environmental changes by salivary salivary pH, amount, periodontal Index in patient with active pulmonary tuberculosis patients. Among the subjects, The experimental group was consisted of 100 patients (50 males and 50 females) of 20-29 years and 100 persons of control group (50 males and 50 females) of 20-29 years. The measurement of salivary amount was performed with wide mouthed plastic (2 Inches) bottle for avoidance of Ionization of SiO2 by using of glass bottle and salivary pH was checked by pH meter 27 radiometer Copenhagen. The results are as follows : 1. The slivary pH does not appear to be characteristic of tuberculous paticents. 2. The obtained salivary amount indicated no significant to the tuberculous patients as compared to the obtained supposedely wealthg individuals. 3. The Russel Index wasfound higher and there had found more periodontal involvement(3 times than normal) in the experimental group.

• Korean Journal of Materials Research
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• v.8 no.9
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• pp.837-842
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• 1998

As the size of the integrated circuit is scaled down the importance of Si cleaning has been emphasized. One of the major concerns is abut the removal of metallic impurities such as Cu and Fe on Si surface. In this study, we intentionally contaminated Cu and Fe on the Si wafers and cleaned the wafer by cleaning splits of the chemical mixture of $\textrm{H}_2\textrm{O}_2$ and HF and the combination of HF treatment with UV/$\textrm{O}_3$ treatment. The contamination level was monitored by TXRF. Surface microroughness of the Si wafers was measured by AFM. The Si wafer surface was examined by SEM. AES analysis was carried out to analyze the chemical composition of Cu impurities. The amount of Cu impurities after intentional contamination was abut the level of $\textrm{10}^{14}$ atoms/$\textrm{cm}^2$. The amount of Cu was decreased down to the level of $\textrm{10}^{10}$ atoms/$\textrm{cm}^2$ by cleaning splits. The repeated treatment exhibited better Cu removal efficiency. The surface roughness caused by contamination and removal of Cu was improved by repeated treatment of the cleaning splits. Cu were adsorbed on Si surface not in a thin film type but in a particle type and its diameter was abut 100-400${\AA}$ and its height was 30-100${\AA}$. Cu was contaminated on Si surface by chemical adsorption. In the case of Fe the contamination level was $\textrm{10}^{13}$ atoms/$\textrm{cm}^2$ and showed similar results of above Cu cleaning. Fe was contaminated on Si surface by physical adsorption and as a particle type.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.7
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• pp.171-175
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• 1996

Gate insulator for Si field emitter is usually formed by e-beam evaporation. However, the evaported oxide requires densification for a stable process and a reduction of gate leakage which results from its Si-rich and nonstoicheiometric structure. In this study, we have developed the process technology able to densify the evaporated oxide in H$_{2}$O ambient. Using this process, we have fabricted thefield emitter array with 625 emitters per pixel, of which gate hole diameter is 1.4.mu.m, for the pixel, anode current of 14.3.mu.A was extracted at a gate bias of 100V and gate leakage was about 0.27% of the total emission current.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.222-222
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• 2011

Titanium dioxide (TiO2) has a number of applications in optics and electronics due to its superior properties, such as physical and chemical stability, high refractive index, good transmission in vis and NIR regions, and high dielectric constant. Atomic layer deposition (ALD), also called atomic layer epitaxy, can be regarded as a special modification of the chemical vapor deposition method. ALD is a pulsed method in which the reactant vapors are alternately supplied onto the substrate. During each pulse, the precursors chemisorb or react with the surface groups. When the process conditions are suitably chosen, the film growth proceeds by alternate saturative surface reactions and is thus self-limiting. This makes it possible to cover even complex shaped objects with a uniform film. It is also possible to control the film thickness accurately simply by controlling the number of pulsing cycles repeated. We have investigated the ALD of TiO2 at 100$^{\circ}C$ using precursors titanium tetra-isopropoxide (TTIP) and H2O on -O, -OH terminated Si surface by in situ X-ray photoemission spectroscopy. ALD reactions with TTIP were performed on the H2O-dosed Si substrate at 100$^{\circ}C$, where one cycle was completed. The number of ALD cycles was increased by repeated deposition of H2O and TTIP at 100$^{\circ}C$. After precursor exposure, the samples were transferred under vacuum from the reaction chamber to the UHV chamber at room temperature for in situ XPS analysis. The XPS instrument included a hemispherical analyzer (ALPHA 110) and a monochromatic X-ray source generated by exciting Al K${\alpha}$ radiation (h${\nu}$=1486.6 eV).

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.7
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• pp.1255-1258
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• 2010

In this paper, the $CoSi_2$ thin films with thicknesses of about $5{\mu}m$ were deposited on n-type silicon (111) substrates by RF magnetron sputtering method using a $CoSi_2$ target (99.99%). The flow rate of argon of 50 sccm, substrate temperature of $100^{\circ}C$, RF power of 60 watts, deposition time of 30 minutes, and the vacuum of $1\times10^{-6}$ Torr. The annealing treatments of the $CoSi_2$ thin film were performed from 500, 700 and $900^{\circ}C$ for 1h in air ambient by an electric furnace. In order to investigate the $CoSi_2$ thin film X-ray diffraction patterns were measured using the X-ray diffractometer (XRD). The structure of the thin films were investigated by using scanning the electron microscope (SEM) were used for review. The surface morphology of the thin films was measured with a atomic force microscopy (AFM). Temperature dependence of sheet resistivity and property of Hall effect was measured in the $CoSi_2$ thin film.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.2
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• pp.98-102
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• 2010

This paper describes that single crystalline 3C-SiC (cubic silicon carbide) thin films have been deposited on carbonized Si(100) substrates using hexamethyldisilane (HMDS, $Si_2(CH_3){_6}$) as a safe organosilane single precursor and a nonflammable mixture of Ar and $H_2$ gas as the carrier gas by APCVD at $1280^{\circ}C$. The deposition was performed under various conditions to determine the optimized growth condition. The crystallinity of the 3C-SiC thin film was analyzed by XRD (X-ray diffraction). The surface morphology was also observed by AFM (atomic force microscopy) and voids between SiC and Si interfaces were measured by SEM (scanning electron microscopy). Finally, residual strain and hall mobility was investigated by surface profiler and hall measurement, respectively. From these results, the single crystalline 3C-SiC film had a good crystal quality without defects due to viods, a low residual stress, a very low roughness.

• Current Applied Physics
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• v.18 no.11
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• pp.1268-1274
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• 2018

We have investigated the effects of chemical rounding (CR) on the surface passivation and/or antireflection performance of $AlO_{x^-}$ and $AlO_x/SiN_x:H$ stack-passivated pyramid textured $p^+$-emitters with two different boron doping concentrations, and on the performance of bifacial n-PERT Si solar cells with a front pyramid textured $p^+$-emitter. From experimental results, we found that chemical rounding markedly enhances the passivation performance of $AlO_x$ layers on pyramid textured $p^+$-emitters, and the level of performance enhancement strongly depends on boron doping concentration. Meanwhile, chemical rounding increases solar-weighted reflectance ($R_{SW}$) from ~2.5 to ~3.7% for the $AlO_x/SiN_x:H$ stack-passivated pyramid textured $p^+$-emitters after 200-sec chemical rounding. Consequently, compared to non-rounded bifacial n-PERT Si cells, the short circuit current density Jsc of 200-sec-rounded bifacial n-PERT Si cells with ~60 and ${\sim}100{\Omega}/sq$ $p^+$-emitters is reduced by 0.8 and $0.6mA/cm^2$, respectively under front $p^+$-emitter side illumination. However, the loss in the short circuit current density Jsc is fully offset by the increased fill factor FF by 0.8 and 1.5% for the 200-sec-rounded cells with ~60 and ${\im}100{\Omega}/sq$ $p^+$-emitters, respectively. In particular, the cell efficiency of the 200-sec-rounded cells with a ${\sim}100{\Omega}/sq$ $p^+$-emitter is enhanced as a result, compared to that of the non-rounded cells. Based on our results, it could be expected that the cell efficiency of bifacial n-PERT Si cells would be improved without additional complicated and costly processes if chemical rounding and boron doping processes can be properly optimized.

• Korean Journal of Materials Research
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• v.9 no.11
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• pp.1049-1054
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• 1999

Two-step growth method is suggested to enhance the alignment of highly oriented diamond films. (100) Si wafers are pretreated with negative biasing of - 200 V at $850^{\circ}C$ for 20 min with 4 % methane in hydrogen plasma. The pretreated wafers are grown under the lst-step growth conditions(2 % CH$_4$ in H$_2$, $810^{\circ}C$) from 2 hr to 35 hr, in order to obtain <100> textured films. The 2nd-step growth(2 % CH$_4$ in H$_2$, $850^{\circ}C$) is carried out to make diamond films having (100) growth planes, which are parallel to the substrate. The alignment of the films after the 1st-step growth, has been analyzed by {111} X-ray pole figure, which is improved abruptly with increasing film thickness. However, the pyramidal surface morphology is inevitable. These morphology is flattened after the 2nd-step growth by developing the (100) facets parallel to the substrate. The alignment of the highly oriented textured films after the two-step growth depends on the thickness of the 1st-step growth film.