In this paper, we investigated the effect of the passivation stack with Al2O3, hydrogenated silicon nitride (SiNx:H) stack and Al2O3, silicon oxynitride (SiONx) stack in the n type bifacial solar cell on monocrystalline silicon. SiNx:H and SiONx films were deposited by plasma enhanced chemical vapor deposition on the Al2O3 thin film deposited by thermal atomic layer deposition. We focus on passivation properties of the two stack structure after laser ablation process in order to improve bifaciality of the cell. Our results showed SiNx:H with Al2O3 stack is 10 mV higher in implied open circuit voltage and 60 μs higher in minority carrier lifetime than SiONx with Al2O3 stack at Ni silicide formation temperature for 1.8% open area ratio. This can be explained by hydrogen passivation at the Al2O3/Si interface and Al2O3 layer of laser damaged area during annealing.

Recent industrialization has led to a high demand for the use of fossil fuels. Therefore, the need for producing hydrogen and its utilization is essential for a sustainable society. For an eco-friendly future technology, photoelectrochemical water splitting using solar energy has proven promising amongst many other candidates. With this technique, semiconductors can be used as photocatalysts to generate electrons by light absorption, resulting in the reduction of hydrogen ions. The photocatalysts must be chemically stable, economically inexpensive and be able to utilize a wide range of light. From this perspective, cuprous oxide(Cu2O) is a promising p-type semiconductor because of its appropriate band gap. However, a major hindrance to the use of Cu2O is its instability at the potential in which hydrogen ion is reduced. In this study, gold is used as a bottom electrode during electrodeposition to obtain a preferential growth along the (111) plane of Cu2O while imperfections of the Cu2O thin films are removed. This study investigates the photoelectrochemical properties of Cu2O. However, severe photo-induced corrosion impedes the use of Cu2O as a photoelectrode. Two candidates, TiO2 and SnO2, are selected for the passivation layer on Cu2O by by considering the Pourbaix-diagram. TiO2 and SnO2 passivation layers are deposited by atomic layer deposition(ALD) and a sputtering process, respectively. The investigation of the photoelectrochemical properties confirmed that SnO2 is a good passivation layer for Cu2O.

본 연구에서는 용액 공정으로 제작된 단분자 기반의 유기 반도체 전계효과 트랜지스터에 적용된 보호막이 유기 트랜지스터의 전기적 안정성에 미치는 영향에 대해여 살펴보았다. Solvay社에서 제공한 용액 공정형 유기 단분자 반도 체를 채널로 사용하여 제작한 유기 트랜지스터는 약 1 cm2/Vs의 상대적으로 높은 이동도를 보였으며, 대략 2.5 ~ 20 k Ωcm 범위의 낮은 접촉저항을 가진 것으로 측정되었다. 무엇보다 중요한 것은, 제작한 유기 트랜지스터에 불소원자가 함유된 Hyflon AD를 보호막으로 적용하였을 때, 보호막을 적용하기 전에 비해 훨씬 더 향상된 전기적 안정성을 보였 다. 이는 불소원자가 함유된 Hyflon AD 고분자막이 대기 중의 수분을 효과적으로 차단하기 때문으로 추측된다.

In this study, the surface passivation process for InP-based quantum dots (QDs) is investigated. Surface coating is performed with poly(methylmethacrylate) (PMMA) and thioglycolic acid. The quantum yield (QY) of a PMMA-coated sample slightly increases by approximately 1.3% relative to that of the as-synthesized InP/ZnS QDs. The QYs of the uncoated and PMMA-coated samples drastically decrease after 16 days because of the high defect state density of the InP-based QDs. PMMA does not have a significant effect on the defect passivation. Thioglycolic acid is investigated in this study for the effective surface passivation of InP-based QDs. Surface passivation with thioglycolic acid is more effective than that with the PMMA coating, and the QY increases from 1.7% to 11.3%. ZnS formed on the surface of the InP QDs and S in thioglycolic acid show strong bonding property. Additionally, the QY is further increased up to 21.0% by the photochemical reaction. Electron–hole pairs are formed by light irradiation and lead to strong bonding between the inorganic and thioglycolic acid sulfur. The surface of the InP core QDs, which does not emit light, is passivated by the irradiated light and emits green light after the photochemical reaction.

Silicon nitride (SiNx:H) films made by plasma enhanced chemical vapor deposition (PECVD) are generally used as antireflection layers and passivation layers on solar cells. In this study, we investigated the properties of silicon nitride (SiNx:H) films made by PECVD. The passivation properties of SiNx:H are focused on by making the antireflection properties identical. To make equivalent optical properties of silicon nitride films, the refractive index and thickness of the films are fixed at 2.0 and 90 nm, respectively. This limit makes it easier to evaluate silicon nitride film as a passivation layer in realistic application situations. Next, the effects of the mixture ratio of the process gases with silane (SiH4) and ammonia (NH3) on the passivation qualities of silicon nitride film are evaluated. The absorption coefficient of each film was evaluated by spectrometric ellipsometry, the minority carrier lifetimes were evaluated by quasi-steady-state photo-conductance (QSSPC) measurement. The optical properties were obtained using a UV-visible spectrophotometer. The interface properties were determined by capacitancevoltage (C-V) measurement and the film components were identified by Fourier transform infrared spectroscopy (FT-IR) and Rutherford backscattering spectroscopy detection (RBS) - elastic recoil detection (ERD). In hydrogen passivation, gas ratios of 1:1 and 1:3 show the best surface passivation property among the samples.

Silicon oxynitride that can be deposited two times faster than general SiNx:H layer was applied to fabricate the passivation protection layer of atomic layer deposition (ALD) Al2O3. The protection layer is deposited by plasma-enhanced chemical vapor deposition to protect Al2O3 passivation layer from a high temperature metallization process for contact firing in screen-printed silicon solar cell. In this study, we studied passivation performance of ALD Al2O3 film as functions of process temperature and RF plasma effect in plasma-enhanced chemical vapor deposition system. Al2O3/SiON stacks coated at 400 oC showed higher lifetime values in the as-stacked state. In contrast, a high quality Al2O3/SiON stack was obtained with a plasma power of 400 W and a capping-deposition temperature of 200 oC after the firing process. The best lifetime was achieved with stack films fired at 850 oC. These results demonstrated the potential of the Al2O3/SiON passivated layer for crystalline silicon solar cells.

During sintering of Ni-electrode multi-layer ceramic capacitors (MLCCs), the Ni electrode often becomes discontinuous because of its lower sintering temperature relative to that of BaTiO3. In an attempt to retard the sintering of Ni, we introduced passivation of the Ni powder. To find the optimal passivation conditions, a thermogravimetric analysis (TGA) was conducted in air. After passivation at 250oC for 11 h in air, a nickel oxide shell with a thickness of 4- 5 nm was formed on nickel nanoparticles of 180 nm size. As anticipated, densification of the compacts of the passivated Ni/NiO core-shell powder was retarded: the starting temperature of densification increased from ~400oC to ~600oC in a 97N2-3H2 (vol %) atmosphere. Grain growth was also retarded during sintering at temperatures of 750 and 1000oC. When the sintering atmosphere was changed from wet 99.93N2-0.07H2 to wet 99.98N2-0.02H2, the average grain size decreased at the same sintering temperature. The conductivity of the passivated powder sample sintered at 1150oC for 8 h in wet 99.93N2-0.07H2 was measured to be 3.9 × 104 S/cm, which is comparable with that, 4.6 × 104 S/ cm, of the Ni powder compact without passivation. These results demonstrate that passivation of Ni is a viable means of retarding sintering of a Ni electrode and hence improving its continuity in the fabrication of BaTiO3-based multi-layer ceramic capacitors.

Fuel test loop is an irradiation test facility which can conduct the irradiation tests of nuclear fuels and materials at HANARO. The FTL simulates the operating conditions of commercial nuclear power plants such as their pressure, temperature, flow and water chemistry to conduct the irradiation and thermo-hydraulic tests. The passivation of the fuel test loop was performed for the main cooling system in the commissioning stage with satisfaction of the operation criterion such as temperature and water chemistry conditions. The experimental results show that the passivation was completed successfully.

This paper investigates the dependence of a-Si:H/c-Si passivation and heterojunction solar cell performances on various cleaning processes of silicon wafers. It is observed that the passivation quality of a-Si:H thin-films on c-Si wafers depends highly on the initial H-termination properties of the wafer surface. The effective minority carrier lifetime (MCLT) of highly H-terminated wafer is beneficial for obtaining high quality passivation of a-Si:H/c-Si. The wafers passivated by p(n)-doped a-Si:H layers have low MCLT regardless of the initial H-termination quality. On the other hand, the MCLT of wafers incorporating intrinsic (i) a-Si:H as a passivation layer shows sensitive variation with initial cleaning and H-termination schemes. By applying the improved cleaning processes, we can obtain an MCLT of 100μsec after H-termination and above 600μsec after i a-Si:H thin film deposition. By adapting improved cleaning processes and by improving passivation and doped layers, we can fabricate a-Si:H/c-Si heterojunction solar cells with an active area conversion efficiency of 18.42%, which cells have an open circuit voltage of 0.670V, short circuit current of 37.31 mA/cm2 and fill factor of 0.7374. These cells show more than 20% pseudo efficiency measured by Suns-Voc with an elimination of series resistance.

This article shows various factors that influence the thermal-cycling reliability of semiconductor devices utilizing the lead-on-chip (LOC) die attach technique. This work details how the modification of LOC package design as well as the back-grinding and dicing process of semiconductor wafers affect passivation reliability. This work shows that the design of an adhesion tape rather than a plastic package body can play a more important role in determining the passivation reliability. This is due to the fact that the thermal-expansion coefficient of the tape is larger than that of the plastic package body. Present tests also indicate that the ceramic fillers embedded in the plastic package body for mechanical strengthening are not helpful for the improvement of the passivation reliability. Even though the fillers can reduce the thermal-expansion of the plastic package body, microscopic examinations show that they can cause direct damage to the passivation layer. Furthermore, experimental results also illustrate that sawing-induced chipping resulting from the separation of a semiconductor wafer into individual devices might develop into passivation cracks during thermal-cycling. Thus, the proper design of the adhesion tape and the prevention of the sawing-induced chipping should be considered to enhance the passivation reliability in the semiconductor devices using the LOC die attach technique.

HBr을 이용한 트렌치 식각시 식각 방지막의 형성과 이들이 결함 생성 및 분포에 미치는 영향을 고분해능 투과전자현미경을 이용하여 연구하였다. O2 및 다른 첨가 가스로 SiOxFy, SiOxBry 등의 식각 방지막을 표면에 형성시켜 벽면 undercut을 방지하고 표면의 거칠기를 감소할 수 있었으며, 이후의 트렌치 채움 공정에서 void 가 없는 잘 채원진 구조를 얻을 수 있었다. 형성된 식각 방지막은 격자 결함의 생성 및 이들의 분포에 영향을 미쳤다. 대부분의 식각 유도 결함들은 트렌치 바닥의 가장자리에서 10Å 이내의 깊이로 분포하였으며, 잔류막의 두께에 의존하였다. 두꺼운 잔류막층 아래로는 결함들이 거의 사라졌으며, 결함층의 깊이와 잔류막 두께는 대체로 반비례하는 것을 나타났다. 기판 내에 존재하는 결정학적인 결함들은 식각종의 입사각이나 에너지에 의존하는 반면에,식각된 표면에서 관찰되는 결함들은 트렌치 식각동안 형성되는 이러한 잔류막의 두께에 크게 의존하는 것으로 나타났다.

차세대 반도체 배선분야에서, Cu박막은 현재의 AI을 대체할 물질로서 대두되고 있으며 CVD에 의한 선택적 증착은 Cu의 patterning과 관련하여 상당한 관심을 일으키고 있다. 본 연구에서는 (hfac)Cu(VTMS)의 유기원료를 사용하여, CVD공정변수, 운반기체, 표면 처리 공정에 따른 SiO2, TiN, AI기판에 대한 선택성을조사하였다. 선택성은 저온(150˚C), 저합(0.3Torr)에서 향상될 수 있었으며, 특히, HMDS in-situ-predosing공정에 의해 더욱 향상될 수 있었다. 모든 경우에 대해, H2운반기체가 Ar 보다 짧은 incubation time과 높은 증착 속도가 얻어졌으며, Cu입자들의 크기가 작고 연결상태가 보다 양호하였다. 이는 H2경우에 기판표면에 원료가 흡착되어 핵을 형성시키는 위치 (-OH)가 보다 많이 제공되기 때문으로 여겨진다. 이러한 미세구조의 차이는 H2경우에 보다 낮은 비저항을 얻게 했다. HMDS in-situ predosing공정에 의한 Cu박막내 불순물 차이는 없었으며 뚜렷한 비저항의 차이도 나타나지 않았다.

반도체 공정의 최종 보호막으로 주로 사용되는 PSG (Phosphosilicate class), USG (Undoped silicate glass) 및 SiN 막을 CVD 방식으로 deposition 하여 각 막의 스트레스를 막 두께 또는 대기중 방치시간의 함수로 조사하고 Al 배선의 stress-migration 관점에서 평가했다. 그 결과 PSG 막과 USG 막은 tensile stress를 나타내고 두께증가에 따라 스트레스가 증가하였고, SiN 막은 두께에 관계없이 일정한 compressive stress를 나타내었다. PSG 막은 현저한 스트레스 경시변화를 보여 대기중에 방치시 2일이내로 tensile stress가 compressive stress로 변화되었다. 그 주 원인은 PSG 막의 수분 흡수 때문인것이 FTIR 분석으로 밝혀졌고, 300˚C에서 20분간 anneal 처리로 2.5×109 dyne/cm2의 스트레스 회복이 가능하였다. PSG 막이 포함된 복합막의 경우, 복합막 stress는 PSG 막의 방치시간에 따라 변한다. 즉, 복합막의 스트레스는 복합막을 구성하고 있는 막들의 두께의 함수이다. 또 SiN 막의 강한 압축응력을 완화시켜주는 PSG, USG 막의 스트레스가 큰 인장응력을 나타낼수록 Al 배선의 stress-migration 에 대한 저항은 커진다.