• 반도체디스플레이기술학회지
• /
• 제19권2호
• /
• pp.77-81
• /
• 2020

Silicon wafer etching in micro electro mechanical systems (MEMS) fabrication is challenging to form 3-D structures. Well known Si-wet etch of silicon employs potassium hydroxide (KOH), tetramethylammonium hydroxide (TMAH) and sodium hydroxide (NaOH). However, the existing silicon wet etching process has a fatal disadvantage that etching of the back side of the wafer is hard to avoid. In this study, a wet etching bath for 150 mm wafers was designed to prevent back-side etching of silicon wafer, and we demonstrated the optimized process recipe to have anisotropic wet etching of silicon wafer without any damage on the backside. We also presented the design of wet bath for 300 mm wafer processing as a promising process development.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
• /
• pp.72.2-72.2
• /
• 2010

Nowadays, the crystalline Si Solar cell are expected for economical renewable energy source. The cost of the crystalline Si solar cell are decreasing by improvement of its efficiency and decrease of the cost of the raw Si wafers for Solar cells. This Si wafer based crystalline Si solar cell is the verified technology from several decade of its history. Now, I will introduce one method that can be upgrade the efficiency by using simple and economical method. The name of this method is Rear Side Etching(RSE). The purpose of rear side etching is the elimination of n+ layer of rear side and increase of the flatness. The effects of rear side etching are the improvement of Voc and increase of efficiency by reducement series resistance and forming of uniform BSF. The experimental procedure for rear side etching is very simple. After anti-reflection coating on solar cell wafer, Solar cell wafer is etched by the etching chemical that react with only rear side not front side. This special chemical is no harmful to anti-reflection coating layer. It can only etched rear side of solar cell wafer. We can use etching image by optical microscope, minority carrier life time by WCT 120, SiNx thickness and refractive index by ellipsometer, cell efficiency for the RSE effect measurement. The key point of rear side etching is development of etching process condition that react with only rear side. If we can control this factor, we can achieve increase of solar cell efficiency very economically without new device.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2010년도 추계학술대회 초록집
• /
• pp.53.2-53.2
• /
• 2010

In this study, we focused on our specialized electrode process for Si back-contact crystalline solar cell. It is different from other well-known back-contact cell process for thermal aspect and specialized process. In general, aluminum makes ohmic contact to the Si wafer and acts as a back surface reflector. And, silver is used for low series resistance metal grid lines. Aluminum was sputtered onto back side of wafer. Next, silver is directly patterned on the wafer by screen printing. The sputtered aluminum was removed by wet etching process after rear silver electrode was formed. In this process, the silver paste must have good printability, electrical property and adhesion strength, before and after the aluminum etching process. Silver paste also needs low temperature firing characteristics to reduce the thermal budget. So it was seriously collected by the products of several company of regarding low temperature firing (below $250^{\circ}C$) and aluminum etching endurance. First of all, silver pastes for etching selectivity were selected to evaluate as low temperature firing condition, electrical properties and adhesive strength. Using the nano- and micron-sized silver paste, so called hybrid type, made low temperature firing. So we could minimize the thermal budget in metallization process. Also the adhesion property greatly depended on the composition of paste, especially added resin and inorganic additives. In this paper, we will show that the metallization process of back-contact solar cell was realized as optimized nano-paste characteristics.

• Nuclear Engineering and Technology
• /
• 제49권4호
• /
• pp.881-885
• /
• 2017

This work presents a new technique for discriminating between alpha particles of different energy levels. In a first study, two groups of alpha particles emitted from radium-226 and americium-241 sources were successfully separated using a CR-39 microfilm of appropriate thickness. This thickness was adjusted by chemical etching before and after irradiation so that lower-energy particles were stopped within the detector, while higher-energy particles were revealed on the back side of the detector. The number of tracks on the front side of the microfilm represented all alpha particles incident on that side from the two sources. However, the number of tracks on the back side of the microfilm represented only the long-range alpha particles of higher energy that arrived at that side. Therefore, by subtracting the number of tracks on the back side from the number of tracks on the front side, one could easily determine the number of tracks for the short-range alpha particles of lower energy that remained embedded in the microfilm. Discrimination of the two energy levels is thus achieved in a simple, fast, and reliable process.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
• /
• pp.387.2-387.2
• /
• 2016

Glass texturing is a sufficient method for changing the surface morphology to enhance the light trapping. In this study, glass texturing was applied to the perovskite solar cell for improving the current density. Glass substrates (back-side glass of FTO coated glass substrate) were textured by randomly structure assisted wet etching process using diluted HF solution at a constant concentration of etchants (HF:H2O=1:1). Then, the light trapping properties of suitable films were controlled over a wide range by varying the etching time (1, 2, 3, 4 and 5 min.). The surface texturing changed the reflected light in an angle that it can be reflected by substrate glass surface. As a result, Current density and cell efficiency were affected by light trapping layer using glass texturing method in perovskite solar cells.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1996년도 하계학술대회 논문집 C
• /
• pp.1977-1979
• /
• 1996

Single-crystaIline silicon diaphgrams and features are fabricated without using an etch stop process. The process involves vertical dry etching, double-sided alignment, followed by wet-chemical etching from the back side. The abvantages of this process are that $5{\sim}50{\mu}m$ diaphgrams and features can be fabricated accurately and inexpensively. In addition, since no impurity-based process is introduced, highly uniform and homogenous properties can be achieved

• 반도체디스플레이기술학회지
• /
• 제8권1호
• /
• pp.1-5
• /
• 2009

Typically, single-wafer wet etching is done by dispensing chemical onto the front and back side of spin wafer. The wafer is fixed by a number of chuck pins, which obstruct the chemical flow and would result in the incomplete removal of the remaining film, which can become a source of contamination in the next process. In this paper, we introduce a novel design of wafer chuck, in which chuck pins are groupped into two and each group of pins fixes the substrate alternatively. Two groups of chuck pins fix the high-speed spin substrate with non contact method using a magnetic material. The actual process has been executed to observe the effectiveness of this new wafer chuck. It was found that the new wafer chuck performed better than the conventional wafer chuck for removing the remaining film from the bevel and edge side of substrate.

• 제어로봇시스템학회논문지
• /
• 제14권4호
• /
• pp.361-364
• /
• 2008

Tips of probe card were fabricated using MEMS technology. P-type silicon wafer with $SiO_2$ layer was used as a substrate for fabricating the probe card. Ni-Cr and Au used as seed layer for electroplating Ni were deposited on the silicon wafer. Line patterns for probing devices were formed on silicon wafer by electroplating Ni through mold which formed by MEMS technology. Bridge structure was formed by wet-etching the silicon substrate. AZ-1512 photoresist was used for protection layer of back side and DNB-H100PL-40 photoresist was used for patterning of the front side. The mold with the thickness of $60{\mu}m$ was also formed using THB-120N photoresist and probe tip with thickness of $50{\mu}m$ was fabricated by electroplating process.

• 한국재료학회지
• /
• 제21권5호
• /
• pp.243-249
• /
• 2011

To reduce manufacturing costs of crystalline silicon solar cells, silicon wafers have become thinner. In relation to this, the properties of the aluminium-back surface field (Al-BSF) are considered an important factor in solar cell performance. Generally, screen-printing and a rapid thermal process (RTP) are utilized together to form the Al-BSF. This study evaluates Al-BSF formation on a (111) textured back surface compared with a (100) flat back surface with variation of ramp up rates from 18 to $89^{\circ}C$/s for the RTP annealing conditions. To make different back surface morphologies, one side texturing using a silicon nitride film and double side texturing were carried out. After aluminium screen-printing, Al-BSF formed according to the RTP annealing conditions. A metal etching process in hydrochloric acid solution was carried out to assess the quality of Al-BSF. Saturation currents were calculated by using quasi-steady-state photoconductance. The surface morphologies observed by scanning electron microscopy and a non-contacting optical profiler. Also, sheet resistances and bulk carrier concentration were measured by a 4-point probe and hall measurement system. From the results, a faster ramp up during Al-BSF formation yielded better quality than a slower ramp up process due to temperature uniformity of silicon and the aluminium surface. Also, in the Al-BSF formation process, the (111) textured back surface is significantly affected by the ramp up rates compared with the (100) flat back surface.

• 한국결정성장학회지
• /
• 제9권2호
• /
• pp.157-161
• /
• 1999

초크랄스키 실리콘 기판의 뒷면에 형성된 기계적 손상이 미치는 효과에 대하여 고찰하였다. 기계적 손상의 정도는 레이저 여기/극초단파 반사 광전도 감쇠법에 의한 소수반송자 재결합 수명, 습식산화/선택적 식각 방법, 표면 부위 미소 결함 및 X-선 단면 측정 분석으로 평가하였다. 그 결과, 웨이퍼 뒷면에 가해지는 기계적 손상의 세기가 강할수 록 소수반송자 재결합 수명은 짧아지고, 표면 부위 미소 결함 밀도는 비례적으로 증가하였으며, 산화 유기 적충 결함 밀 도와도 상호 일치하였다. 그래서, 표면 부위 미소 결함 기술은 산화 유기 적층 결함을 측정하는데 있어서 통상적인 부식 방법과는 별도로 사용될 수 있다.