• Title/Summary/Keyword: anisotropic etching

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Effect of Surface Microstructure of Silicon Substrate on the Reflectance and Short-Circuit Current (실리콘 기판 표면 형상에 따른 반사특성 및 광 전류 개선 효과)

  • Yeon, Chang Bong;Lee, Yoo Jeong;Lim, Jung Wook;Yun, Sun Jin
    • Korean Journal of Materials Research
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    • v.23 no.2
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    • pp.116-122
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    • 2013
  • For fabricating silicon solar cells with high conversion efficiency, texturing is one of the most effective techniques to increase short circuit current by enhancing light trapping. In this study, four different types of textures, large V-groove, large U-groove, small V-groove, and small U-groove, were prepared by a wet etching process. Silicon substrates with V-grooves were fabricated by an anisotropic etching process using a KOH solution mixed with isopropyl alcohol (IPA), and the size of the V-grooves was controlled by varying the concentration of IPA. The isotropic etching process following anisotropic etching resulted in U-grooves and the isotropic etching time was determined to obtain U-grooves with an opening angle of approximately $60^{\circ}$. The results indicated that U-grooves had a larger diffuse reflectance than V-grooves and the reflectances of small grooves was slightly higher than those of large grooves depending on the size of the grooves. Then amorphous Si:H thin film solar cells were fabricated on textured substrates to investigate the light trapping effect of textures with different shapes and sizes. Among the textures fabricated in this work, the solar cells on the substrate with small U-grooves had the largest short circuit current, 19.20 mA/$cm^2$. External quantum efficiency data also demonstrated that the small, U-shape textures are more effective for light trapping than large, V-shape textures.

Study on the Etching Characteristics of $0.2\mu\textrm{m}$ fine Pattern of Ta Thin film for Next Generation Lithography Mask (차세대 노광공정용 Ta박막의 $0.2\mu\textrm{m}$ 미세패턴 식각특성 연구)

  • Woo, Sang-Gyun;Kim, Sang-Hoon;Ju, Sup-Youl;Ahn, Jin-Ho
    • Korean Journal of Materials Research
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    • v.10 no.12
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    • pp.819-824
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    • 2000
  • In this research, the etching characteristics of Ta thin film with chlorine plsama have been studied by Electron Cyclotron Resonance (ECR) plasma etching system. The effects of microwave power, RF bias power, working pressure and gas chemistry on the etching profiles have been investigated. The microloading effect, which was observed at fine pattern formation, was effectively suppressed by double step etching, and anisotropic $0.2{\mu\textrm{m}}$ L&S patterns were successfully generated.

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The Development of Deep Silicon Etch Process with Conventional Inductively Coupled Plasma (ICP) Etcher (범용성 유도결합 플라즈마 식각장비를 이용한 깊은 실리콘 식각)

  • 조수범;박세근;오범환
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.17 no.7
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    • pp.701-707
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    • 2004
  • High aspect ratio silicon structure through deep silicon etching process have become indispensable for advanced MEMS applications. In this paper, we present the results of modified Bosch process to obtain anisotropic silicon structure with conventional Inductively Coupled Plasma (ICP) etcher instead of the expensive Bosch process systems. In modified Bosch process, etching step ($SFsub6$) / sidewall passivation ($Csub4Fsub8$) step time is much longer than commercialized Bosch scheme and process transition time is introduced between process steps to improve gas switching and RF power delivery efficiency. To optimize process parameters, etching ($SFsub6$) / sidewall passivation ($Csub4Fsub8$) time and ion energy effects on etching profile was investigated. Etch profile strongly depends on the period of etch / passivation and ion energy. Furthermore, substrate temperature during etching process was found to be an important parameter determining etching profile. Test structures with different pattern size have been etched for the comparison of the aspect ratio dependent etch rate and the formation of silicon grass. At optimized process condition, micropatterns etched with modified Bosch process showed nearly vertical sidewall and no silicon grass formation with etch rate of 1.2 ${\mu}{\textrm}{m}$/ min and the size of scallop of 250 nm.

Fabrication or Si Diaphragm using Optimal Etching Condition of $N_2H_4-H_2O$ Solution ($N_2H_4-H_2O$ 용액의 최적 시작 조건을 이용한 Si diaphragm의 제작)

  • Ju, B.K.;Lee, Y.H.;Kim, H.G.;Oh, M.H.
    • Proceedings of the KIEE Conference
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    • 1989.07a
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    • pp.295-298
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    • 1989
  • Using the anisotropic etching characteristics or $N_2H_4-H_2O$ solution, Si diaphragm was fabricated for the integrated sensor. The optimal composition and temperature of the solution in Si etching process was established to be 50mol% $N_2H_4$ in water at $105{\pm}2^{\circ}C$ for both higher etch rate(=$2.6{\mu}m/min$) and better surface quality of etched {100} planes. Under the optimal etching condition, the electrochemical etch stop technique was employed to form Si diaphragm for pressure sensor and diaphragm thickness was exactly controlled to $20{\pm}2{\mu}m$.

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Design and Fabrication of a Silicon Piezoresistive Accelerometer using SOI Structure (SOI 구조를 이용한 실리콘 압저항 가속도계의 설계 및 제작)

  • Yang, Eui-Hyeok;Yang, Sang-Sik;Han, Sang-Woo
    • Proceedings of the KIEE Conference
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    • 1993.11a
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    • pp.192-194
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    • 1993
  • In this paper, a silicon piezoresistive accelerometer of which the cantilevers have uniform thickness is designed and fabricated with SOI wafer. The accelerometer consists of a seismic mass and four cantilevers, and is fabricated mainly by the anisotropic etching method using EPW etchant. The fabrication processes are that of the frontside processes including the etching of the cantilevers and the doubleside alignment holes, the diffusion of the piezoresisters and patterning of the contact windows, and the metal connection process, and that of the backside processes including the etching of the shallow cavity and the seismic mass. Because of the uniformity of thickness, the performance of the accelerometer fabricated with SOI wafer is expected to be better than that of accelerometer fabricated by the time-controlled etching method.

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Micromachining of Si substrate Using Electrochemical Etch-Stop in Aqueous TMAH/IPA/pyrazine Solution (TMAH/IPA/Pyrazine 수용액에서 전기화학적 식각정지법을 이용한 Si 기판의 미세가공)

  • 박진성;정귀상
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1997.11a
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    • pp.397-400
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    • 1997
  • This paper presentes the characteristics of Si anisotropic etching and electrochemical etch-stop in aqueous TMAH/IPA/pyrazine solution. (100) Si etching rate of 0.747 $\mu\textrm{m}$/min which faster 86% than TMAH 25 wt.%/IPA 17 vol.% solution was obtained using best etching condition at TMAH 25 wt.%/IPA 17 vol.%/pyrazine 0.1 g and the etching rate of (100) Si was decreased with more additive quantity of pyrazine. I-V curve of p-type Si in TMAH/IPA/pyrazine was obtained. OCP(Open Circuit Potential) and PP(Passivation Potential) were -2 V and -0.9 V, respectively. Si diaphragms were obtained by electrochemical etch-stop in aqueous TMAH/IPA/pyrazine solution.

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Study on the Masking Effect of the Nanoscratched Si (100) Surface and Its Application to the Maskless Nano Pattern fabrication (마스크리스 나노 패턴제작을 위한 나노스크래치 된 Si(100) 표면의 식각 마스크 효과에 관한 연구)

  • 윤성원;강충길
    • Journal of the Korean Society for Precision Engineering
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    • v.21 no.5
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    • pp.24-31
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    • 2004
  • Masking effect of the nanoscratched silicon (100) surface was studied and applied to a maskless nanofabrication technique. First, the surface of the silicon (100) was machined by ductile-regime nanomachining process using the scratch option of the Nanoindenter${ \circledR}$ XP. To clarify the possibility of the nanoscratched silicon surfaces for the application to wet etching mask, the etching characteristic with a KOH solution was evaluated at room temperature. After the etching process, the convex nanostructures were made due to the masking effect of the mechanically affected layer. Moreover, the height and the width of convex structures were controlled with varying normal loads during nanoscratch.

Reactive ion Etching Characterization of SiC Film Deposited by Thermal CVD Method for MEMS Application (MEMS 적용을 위한 Thermal CVD 방법에 의해 증착한 SiC막의 반응성 이온 Etching 특성 평가)

  • 최기용;최덕균;박지연;김태송
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.17 no.3
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    • pp.299-304
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    • 2004
  • In recent years, silicon carbide has emerged as an important material for MEMS application. In order to fabricate an SiC film based MEMS structure by using chemical etching method, high operating temperature is required due to high chemical stability Therefore, dry etching using plasma is the best solution. SiC film was deposited by thermal CVD at the temperature of 100$0^{\circ}C$ and pressure of 10 torr. SiC was dry etched with a reactive ion etching (RIE) system, using SF$_{6}$/O$_2$ and CF$_4$/O$_2$ gas mixture. Etch rate has been investigated as a function of oxygen concentration in the gas mixture, rf power, working pressure and gas flow rate. Etch rate was measured by surface profiler and FE-SEM. SF$_{6}$/O$_2$ gas mixture showed higher etch rate than CF$_4$/O$_2$ gas mixture. Maximum etch rate appeared at RF Power of 450W. $O_2$ dilute mixtures resulted in an increasing of etch rate up to 40%, and the superior anisotropic cross section was observe

Anisotropic etching characteristics of single crystal silicon by KOH and KOH-IPA solutions (KOH 용액 및 KOH-IPA 혼합용액에 의한 단결정 실리콘의 이방성식각 특성)

  • 조남인;천인호
    • Journal of the Korean Vacuum Society
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    • v.11 no.4
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    • pp.249-255
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    • 2002
  • For a formation of membrane structures, single crystal silicon wafers have been anisotropically etched with solutions of KOH and KOH-IPA. The etching rate was observed to be strongly dependent upon the etchant temperature and concentration. Mask patterns for the etching experiment was aligned to incline $45^{\circ}$on the primary flat of the silicon wafer. The different etching characteristics were observed according to pattern directions and etchant concentration. When the KOH concentration was fixed to 20 wt%, the U-groove etching shape was observed for the etching temperature of above $80^{\circ}C$, and V-groove shapes observed at below $80^{\circ}C$. Hillocks, which were generated at the etched silicon surfaces, has been decreased as the increasing of the etchant temperature and concentration.

Reactive ion etching characterization of SiC film deposited by thermal CVD method for MEMS application (MEMS 적용을 위한 thermal CVD 방법에 의해 증착한 SiC막의 etching 특성 평가)

  • Choi, Gi-Yong;Choi, Duck-Kyun;Park, Ji-Yeon;Kim, Tae-Song
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.07b
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    • pp.868-871
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    • 2003
  • In recent years, silicon carbide has emerged as an important material for MEMS application. In order to fabricate an SiC film based MEMS structure by using chemical etching method, high operating temperature is required due to high chemical stability. Therefore, dry etching using plasma is the best solution. SiC film was deposited by thermal CVD at the temperature of $1000^{\circ}C$ and pressure of 10 torr. SiC was dry etched with a reactive ion etching (RIE) system, using $SF_6/O_2$ and $CF_4/O_2$ gas mixture. Etch rate have been investigated as a function of oxygen concentration in the gas mixture, RF power, and working pressure. Etch rate was measured by surface profiler and FE-SEM. $SF_6/O_2$ gas mixture has been shown high etch rate than $CF_4/O_2$ gas mixture. Maximum etch rate appeared at 450W of RF power. $O_2$ dilute mixtures resulted in an increasing of etch rate up to 40%, and the superior anisotropic cross section was observed.

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