• Journal of the Institute of Electronics Engineers of Korea SD
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• 제41권3호
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• pp.9-14
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• 2004

In this study, Si anisotropic etching characteristics of tetramethylammonium hydroxide (TMAH)/ ammonium persulfate(AP)/isopropyl alcohol(IPA) solutions were investigated to realize the optimum structure of a diaphragm for the piezoresistive pressure sensor application. Due to its low toxicity and its high compatibility with the CMOS processing, TMAH was used as Si anisotropic etchants. The variations of Si etch rate on the etching temperature, TMAH concentration, and etching time were obtained. With increasing the etching temperature and decreasing TMAH concentrations, the Si etch rate is increased while a significant non-unifonnity exists on the etched surface because of formation of hillocks on the (100) surface. The addition of IPA to TMAH solution leads to smoother etched surfaces but, makes the Si etch rate lower. However, with the addition of AP to TMAH solution, the Si etch rate is increased and an improvement in flatness on the etching front is observed. The Si etch rate is also maximized with increasing the number of addition of AP to TMAH solution per one hour. The Si square membranes of 20${\mu}{\textrm}{m}$ thickness and l00-400${\mu}{\textrm}{m}$ one-side length were fabricated successfully by applying optimum Si etching conditions of TMAH/AP solutions.

• Proceedings of the KIEE Conference
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• 대한전기학회 1995년도 하계학술대회 논문집 C
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• pp.1428-1430
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• 1995

In this study we fabricate Knife type Si-tip array using (110) Si wafer. We can fabricate vertical structure by anisotropic etching using EPW and observe it by SEM. After the step, we perform isotropic etching and oxidation sharpening of the structure and also observe it by SEM, respectively. The purpose of isotropic etching is to reduce the oxidation time. We attain a optimal tip whose radius is about $100{\AA}$ after anisotropic etching 2.25 min.+isotropic etching 5 min.+oxidation 1 hour and 23 min.

• Korean Journal of Metals and Materials
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• 제46권6호
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• pp.377-381
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• 2008

Prism sheet of LCD BLU which depends on supply from Japan and U.S.A was studied by using Si anisotropic etching and injection molding technologies. First, the prism sheet was patterned on Si wafer through photolithography, and the best conditions of Si etching were determined through etching Si wafer with TMAH to obtain straight optimized zigzag patterns, and a cross pattern to provide light diffusion and concurrent focusing. The etch rate of TMAH was concluded to be constant for $25wt%-70^{\circ}C$ condition. Ni stamp of prism sheet was made by electrodeposition using patterned Si wafer, normal or fast H/C(Heating/Cooling) injections were carried out to fabricate prism sheet. It was known that fast H/C injection could fabricate prism sheet more accurately than normal injection. Zigzag patterns and the cross pattern showed higher transmissivity than the straight patterns because of light diffusion through diagonal direction. The fast H/C injection for zigzag patterns showed lower transmissivity than normal injection because there occurred more light diffusion through precise injection patterns, but the fast H/C injection for straight patterns showed only refraction without diffusion, causing lower transmissivity than normal injection.

• Journal of Electrical Engineering and information Science
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• 제2권5호
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• pp.108-113
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• 1997

In this paper, the optimum condition of (110) Si etching with the potassium hydroxide(KOH) etchant is presented. Although several researches on (110) Si anisotropic etching have been studied, there has been lack of effects of mask quality and etching conditions on the selectivity and the roughness o the etched surface. Three kinds of masks (film, emulsion and E-beam mask) were used in order to verify the effect of etching properties. Anisotropic bulk etching depends on the crystalline orientation and the concentration and temperature of the etchant. In order to investigate the effect of etching conditions on selectivity and the roughness of the etched surface, the concentration of the etchant was varied from 35 to 45 per cent in weight with increments by 5 per cent and the temperature was changed from 70 to 90$^{\circ}C$ with increments by 10$^{\circ}C$. The combination of the temperature of 70$^{\circ}C$ and the concentration of 40wt.% was found to be the optimum etching condition for high selectivity. Etched surfaces show minimum surfaces show minimum surface roughness at a temperature of 80$^{\circ}C$ and a concentation of 40wt.%. Comb structures with various comb widths were fabricated and the lengths of the combs wree measured with several etching time durations. A micro comb structure 525$\mu\textrm{m}$ high was fabricated for MEMS application.

• Journal of the Microelectronics and Packaging Society
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• 제19권4호
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• pp.51-56
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• 2012

In order to fabricate through-Si-vias for thermal vias by using wet etching process, anisotropic etching behavior of Si substrate was investigated as functions of concentration and temperature of TMAH solution in this study. The etching rate of 5 wt%, 10 wt%, and 25 wt% TMAH solutions, of which temperature was maintained at $80^{\circ}C$, was $0.76{\mu}m/min$, $0.75{\mu}m/min$, and $0.30{\mu}m/min$, respectively. With changing the temperature of 10 wt% TMAH solution to $20^{\circ}C$ and $50^{\circ}C$, the etching rate was reduced to $0.067{\mu}m/min$ and $0.233{\mu}m/min$, respectively. Through-Si-vias of $500{\mu}m$-depth could be fabricated by etching a Si substrate for 5 hours in 10 wt% TMAH solution at $80^{\circ}C$ after forming same via-pattern on each side of the Si substrate.

• Proceedings of the KWS Conference
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• 대한용접접합학회 2006년도 춘계 학술대회 개요집
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• pp.16-17
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• 2006

We researched by the characteristic of a anisotropic etching of Si wafer and the Si career concerning the flip chip solder bump. Connectors and Anisotropic Conductive Film (ACF) method was already applied to board-to-board interconnection. In place of them, we have focused on board to board interconnection with solder bump by Si carrier, which has been used as Flip chip bonding technology. A major advantage of this technology is that the Flexible Printed Circuit (FPC) is connected in the same solder reflow process with other surface mount devices. This technology can be applied to semiconductors and electronic devices for higher functionality, integration and reliability.

• Proceedings of the Materials Research Society of Korea Conference
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• 한국재료학회 1997년도 한국재료학회 춘계학술발표회
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• pp.26-26
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• 1997

• Journal of the Semiconductor & Display Technology
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• 제2권4호
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• pp.37-40
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• 2003

We have studied micro-machining technologies to fabricate parts and sensors used in the semiconductor equipment. The studies were based on the silicon integrated circuit processes, and composed of the anisotropic etching of single crystal silicon to fabricate a membrane structure for hot and cold junctions in the infrared absorber. KOH and TMAH were used as etching solutions for the anisotropic wet etching for membrane structure formation. The etching characteristic was observed for the each solution, and etching rate was measured depending upon the temperature and concentration of the etching solution. The different characteristics were observed according to pattern directions and etchant concentration. The pattern was made to incline $45^{\circ}$ on the primary flat, and optimum etching property was obtained in the case of 30 wt% and $90^{\circ}C$ of KOH etching solution for the formation of the membrane structure.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제14권2호
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• pp.117-122
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• 2001

In this paper, we report on photoelectrochemical etching process of 6H-SiC semiconductor wafer. The etching was performed in two-step process; anodization of SiC surface to form a deep porous layer and thermal oxidation followed by an HF dip. Etch rate of about 615${\AA}$/min was obtained during the anodization using a dilute HF(1.4wt% in H$_2$O) electrolyte with the etching potential of 3.0V. The etching rate was increased with the bias voltage. It was also found out that the adition of appropriate portion of H$_2$O$_2$ into the HF solution improves the etching rate. The etching process resulted in a higherly anisotropic etching characteristics and showed to have a potential for the fabrication of SiC devices with a novel design.

• Journal of the Korean Institute of Telematics and Electronics
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• 제24권1호
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• pp.91-96
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• 1987

Plasma etching can obtain less damaged etch surface than reactive ion etching. This study was performed to get anisotropic etching characteristics of Si using two step etching technique with C2CIF5 and SF6 gas mixture. The results show that the etch rate and aspect ratio of silicon was increased with increment of SF6 contents. The bulging phenomenon on trench side wall in the plasma one-step etching technique was eliminated by the two step etching technique. The anisotropy was decreased from 12(at 120m Torr) to 2.2(at 400m Torr) with increasing the chamber pressure. At the low rf power (350 watts) anisotrpy of silicon was obtained 7 lower than that of high rf power (650 watts. A:~9). In Summary we obtained anisotropic etching profiles of silicon with e 6\ulcornerm depth by using the plasma two-step etching technique.