TMAH/IPA/pyrazine 용액에서의 전기화학적 식각정지특성

정귀상,박진성 한국센서학회 1998 센서학회지 Vol.7 No.6

This paper describes electrochemical etch-stop characteristics in TMAH/IPA/pyrazine solution. I-V curves of n- and p-type Si in TMAH/IPA/pyrazine solution were obtained. OCP(Open Circuit Potential) and PP (Passivation Potential) of p-type Si were -l.2 V and 0.1 V, and of n-type Si were -1.3 V and -0.2 V, respectively. Both n- and p-type Si, etching rates were abruptly decreased at potentials anodic to the PP. The etch-stop characteristics in TMAH/TPA/pyrazine solution were observed. Since accurate etching stop occurs at pn junction, Si diaphragms having thickness of epi-layer were fabricated. Etching rate is highest at optimum etching condition, TMAH 25wt.%/IPA 17vo1.%/pyrazine 0.1g/100ml, thus the elapsed time of etch-stop was reduced.

측온저항체 온도센서가 집적화된 발열저항체형 마이크로 유량센서의 제작 및 특성

정귀상,홍석우 한국전기전자재료학회 2000 전기전자재료학회논문지 Vol.13 No.7

This paper describes on the fabrication and characteristics of hot-film type micro-flowsensors integrated with Pt-RTD(resistance thermometer device) and micro-heater on the Si membrane in which MgO thin-film was used as medium layer in order to improve adhesion of Pt thin-film to SiO$_2$layer. The MgO layer improved adhesion of Pt thin-film to SiO$_2$layer without any chemical reactions to Pt thin-film under high annealing temperatures. Output voltages increased due to increase of heat-loss from sensor to external. The output voltage was 82 mV at $N_2$flow rate of 2000 sccm/min heating power of 1.2 W. The response time($\tau$:63%) was about 50 msec when input flow was stepinput

실리콘기판 직접접합기술을 이용한 SOI 홀 센서의 제작과 그 특성

정귀상 한국전기전자재료학회 1995 電氣電子材料學會誌 Vol.8 No.2

This paper describes the fabrication and characteristics of a Si Hall sensor fabricated on a SOI (Si-on-insulator) structure. The SOI structure was formed by SDB(Si-wafer direct bonding) technology and the insulator of the SOI structure was used as the dielectrical isolation layer of a Hall sensor. The Hall voltage and sensitivity of the implemented SDB SOI Hall sensors showed good linearity with respect to the applied magnetic flux density and supplied current. The product sensitivity of the SDB SOI Hall sensor was average 600V/A.T and its value has been increased up to 3 times compared to that of bulk Si with buried layer of 10.mu.m. Moreover, this sensor can be used at high-temperature, high-radiation and in corrosive environments.

맴브레인 구조를 이용한 미세발열체형 유량센서의 제작과 그 특성

정귀상,노상수 한국전기전자재료학회 1998 전기전자재료학회논문지 Vol.11 No.11

This paper describes the characteristics of Pt microheater using aluminum oxide films as medium layer and its application to flow sensors. Pt microheater have heating temperature of $390^{\circ}C$ at heating power of 1.2 W. Output voltages of flow sensors which were fabricated by integrating sensing-part with heating-part increase as gas flow rate and its conductivity increase. At $O_2$ flow rate of 2000 sccm, heating power of 0.8 W, output voltage of flow sensor is 101 mV under bridge-applied voltage of 5 V.

극한 환경 MEMS용 옴익 접촉을 위한 다결정 3C-SiC 박막의 표면 처리 효과

정귀상,온창민,Chung, Gwiy-Sang,Ohn, Chang-Min 한국전기전자재료학회 2007 전기전자재료학회논문지 Vol.20 No.3

This paper describes the TiW ohmic contact characteristics under the surface treatment of the polycrystalline 3C-SiC thin film grown on $SiO_2/Si(100)$ wafers by APCVD. The poly 3C-SiC surface was polished by using CMP(chemical mechanical polishing) process and then oxidized by wet-oxidation process, and finally removed SiC oxide layers. A TiW thin film as a metalization process was deposited on the surface treated poly 3C-SiC layer and was annealed through a RTA(rapid thermal annealing) process. TiW/poly 3C-SiC was investigated to get mechanical, physical, and electrical characteristics using SEM, XRD, XPS, AFM, optical microscope, I-V characteristic, and four-point probe, respectively. Contact resistivity of the surface treated 3C-SiC was measured as the lowest $1.2{\times}10^{-5}{\Omega}cm^2$ at $900^{\circ}C$ for 45 sec. Therefore, the surface treatments of poly 3C-SiC are necessary to get better contact resistance for extreme environment MEMS applications.

Fabrication and Characterization of a Polycrystalline 3C-SiC Piezoresistive Micro-pressure Sensor

정귀상 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.56 No.6

This paper describes polycrystalline (poly) 3C-SiC piezoresistive micro-pressure sensors for extreme environment applications prepared with a combination crystal growth technology using chemical vapor deposition (CVD) and micromachining techniques. The device was designed using bulk micromachining under a 1 × 1 mm<SUP>2</SUP> diaphragm and a Si membrane with a thickness of 20 µm. The pressure sensitivities of the fabricated pressure sensors were 0.1 mV/V·bar. The nonlinearity of the devices was ±0.44%·FS, and the hysteresis was 0.61%·FS. The temperature characteristics of the temperature coefficient of sensitivity (TCS), the temperature coefficient of resistance (TCR), and the temperature coefficient of the gauge factor (TCGF) were also evaluated. The TCS of the pressure sensors was -1,867 ppm/℃, the TCR was -792 ppm/℃, and the TCGF to 5 bars was -1,042 ppm/℃, from 25 to 400 ℃.

전기화학적 식각정지에 의한 SDB SOI기판의 제작

정귀상,강경두 한국전기전자재료학회 2000 전기전자재료학회논문지 Vol.13 No.5

This paper describes on the fabrication of a SOI substrate by SDB technology and electrochemical etch-stop. The surface of the thinned SDB SOI substrate is more uniform than that of grinding or polishing by mechanical method and this process was found to be a very accurate method for SOI thickness control. During electrochemical etch-stop leakage current versus voltage curves were measured for analysis of the open current potential(OCP) point the passivation potential(PP) point and anodic passivation potential. The surface roughness and the controlled thickness selectivity of the fabricated a SDB SOI substrate were evaluated by using AFM and SEM respectively.

측온저항체 온도센서용 백금박막의 형성에 관한 연구

정귀상,노상수 한국전기전자재료학회 1996 電氣電子材料學會誌 Vol.9 No.9

Platinum thin films were deposited on Si-wafer by DC rnagnetron sputtering for RTD (resistance thermometer devices). We investigated the physical and electrical characteristics of these films under various conditions, the input power, working vacuum, temperature of substrate and also after annealing these films. The deposition rate was increased with increasing the input power but decreased with increasing Ar gas pressure. The resistivity and sheet resistivity were decreased with increasing the temperature of substrate and the annealing time at 1000.deg. C. At substrate temperature of >$300^{\circ}C$, input power of 7 w/cm$^{2}$, working vacuum of 5 mtorr and annealing conditions of 1000.deg. C and 240 min, we obtained 10.65.mu..ohm..cm, resistivity of Pt thin films and 3800-3900 ppm/.deg. C, TCR(temperature coefficient of resistance). These values are close to the bulk value. These results indicate that the Pt thin films deposited by DC magnetron sputtering have potentiality for the development of Pt RTD temperature sensor.

과부하 방지용 마이크로머시닝 세라믹 박막형 압력센서

정귀상 東西大學校 2002 동서논문집 Vol.8 No.-

This paper describes on the fabrication and characteristics of ceramic thin-film pressure sensors based on Ta-N strain-gauges for harsh environment applications. The Ta-N thin-film strain-gauges are sputter-deposited onto micromachined Si diaphragms with buired cavity for overpressure protectors. The proposed device takes advantages of the good mechanical properties of single-crystalline Si as diaphragms fabricated by SDB (Si-wafer Direct Bonding) and electrochemical etch-stop technology, and in order to extend the operating temperature range, it incorporates relatively the high resistance, stablilty and gauge factor of Ta-N thin-films. The fabricated pressure sensor presents a low temperature coefficient of resistance, high-sensitivity, low non-linearity and excellent temperature stability. The sensitivity is 1.097∼1.21 mV/V·kgf/㎠ in the temperature range of 25∼200℃ and the maximum non-linearity is 0.43 %FS.

고온용 실리콘 홀 센서의 제작

정귀상,류지구 한국전기전자재료학회 2000 전기전자재료학회논문지 Vol.13 No.6

This paper describes on the temperature characteristics of a SDB(silicon-wafer direct bonding) SOI(silicon-on-insulator) Hall sensor. Using the buried oxide $SiO_2$as a dielectrical isolation layer a SDB SOI Hall sensor without pn junction has been fabricated on the Si/ $SiO_2$/Si structure. The Hall voltage and the sensitivity of the implemented SOI Hall sensor show good linearity with respect to the applied magnetic flux density and supplied current. In the temperature range of 25 to 30$0^{\circ}C$ the shifts of TCO(temperature coefficient of the offset voltage) and TCS(temperature coefficient of the product sensitivity) are less than $\pm$6.7$\times$10$_{-3}$ and $\pm$8.2$\times$10$_{-4}$$^{\circ}C$ respectively. These results indicate that the SDB SOI structure has potential for the development of a silicon Hall sensor with a high-sensitivity and high-temperature operation.