고성능 로직용 MOSFET제조에서 활성화영역의 RTP조건결정

송오성 서울시립대학교 산업기술연구소 1997 산업기술연구소논문집 Vol.5 No.-

고스피드의 고성능 로직디바이스의 재조에 있어 특히 MOSFET (metal-oxide-silicon field effect tansistors)의 전기적 특성에 영향을 미치는 이온주입후 소오스와 드레인의 활성화 영역의 RTP(rapid thermal processing) 시간, 온도조건은 매우 중요하였다. 고속 단시간 열처리에 따른 실리콘재료에서의 도판트(dopants)의 거동은 기존의 확산현상으로 예측하기 어려웠다. 실리콘 웨이퍼에 이온주입후 활성화 영역의 RTP에 의한 도판트의 열적활성화를 위해 RTP의 시간, 온도를 30sec-240sec,875c-1000c로 각각 변화시키고, dopants의 농도변화를 SIMS (secondary ion mass spetroscopy)depth profiling을 이용하여 확인하였다. 도판트의 농도변화를 완성된 디바이스의 전기적 특성과 비교하여 최적의 활성화 영역의 RTP조건과 process window를 결정하였다.

함침루비의 감별에 관한 연구

송오성,강윤주 한국귀금속보석학회 2013 한국귀금속보석학회지 Vol.7 No.1

함침루비는 천연루비에 유리질을 함침시킨 루비로 그 시장성이 커지고 있다. 다량의 PbO가 함유된 함침루비의 처리 여부는 확대분석으로 쉽게 유리질의 굴절률 차이와 인클루전의 특징으로 감별이 가능하였으나 최근에는 고온 함침 기술 발달로 기존의 확대 분석에 의한 감별이 어려워지고 있다. 이러한 배경에서 본 연구에서는 심화 검사로 비파괴검사인 확대분석, WD-XRF, 마이크로라만을 통해 분석하였으며, 파괴검사로 TGA와 HF 에칭 검사를 실시하였다. 최근의 고온 함침된 루비를 포함하여 함침루비의 명확한 감별을 위해서 비파괴 검사는 기존의 확대 분석과 WD-XRF분석이 함침 여부를 판별하는데 효과적이었고, 파괴 검사에서는 HF 에칭 검사가 명확한 감별에 유리하였다.

Nitrided oxide에 의한 Boron penetration 방지 효과 연구

송오성 서울시립대학교 산업기술연구소 1998 산업기술연구소논문집 Vol.6 No.1

We need to speed up the logic devices by reducing the gate oxide thickness. Boron penetration, boron atoms diffuse into the silicon substrate during dual gate process, may deteriorate the CMOS logic devices. We investigate the microstructures and the degree of the boron penetration of both 4 nm-thick pure oxide and 4nm-thick nitrided oxide (SiON) with tranmission electron microscope (TEM) and secondary ion mass spectroscopy(SIMS) depth profiling, respectively Boron penetrated through pure oxide layers easily, but never diffuse through SiON layers. We confirmed the amount of the penetrated B concentration through pure SiO2 was 1019 B atoms/cm3, while for SiON was below 1016 B atoms/cm3. The solubility of [N] in SiON was 8 at% in SiO2, layers. We suggest that employing SiON as a gate oxide for high speed logic devices with gate oxide thickness below 4 nm is favorable.

복합 코발트 실리사이드 공정에 따른 게이트 산화막의 특성변화

송오성,정성희,이상돈,이기영,류지호,Song, Oh-sung,Cheong, Seong-hwee,Yi, Sang-don,Lee, Ki-yung,Ryu, Ji-ho 한국재료학회 2003 한국재료학회지 Vol.13 No.11

Gate length, height, and silicide thickness have all been shrinking linearly as device density has progressively increased over the years. We investigated the effect of the cobalt diffusion during the silicide formation process on the 60$\AA$-thick gate oxide lying underneath the Ti/Co and Co/Ti bilayers. We prepared four different cobalt silicides, which have similar sheet resistance, made from the film structure of Co/Ti(interlayer), and Ti(capping layer)/Co, and peformed the current-voltage, time-to-break down, and capacitance-voltage measurements. Our result revealed that the cobalt silicide process without the Ti capping layer allowed cobalt atoms to diffuse into the upper interface of gate oxides. We propose that 100$\AA$-thick titanium interlayer may lessen the diffusion of cobalt to gate oxides in 1500-$\AA$ height polysilicon gates.

Co-22%Cr 합금박막의 자가정렬형 나노구조에 의한 자기적 물성

송오성,이영민,Song, O-Seong,Lee, Yeong-Min 한국재료학회 2001 한국재료학회지 Vol.11 No.12

Co-22%Cr alloy films are promising for high-density perpendicular magnetic recording media with their perpendicular anisotropy and large coercivity of 3000 Oe. We observed that a self organized nano structure(SONS) of fine ferromagnetic Co-enriched phase and paramagnetic Cr-enriched phase appears inside the grain of Co-Cr magnetic alloy thin films at the elevated substrate temperature after do-sputtering. We prepared 1000 $\AA$-thick Co-22%Cr films on 2000 $\AA$- SiO$_2$/Si(100) substrates at the deposition rate of 100 $\AA$/min with substrate temperatures of 3$0^{\circ}C$, 10$0^{\circ}C$, 15$0^{\circ}C$, 20$0^{\circ}C$, 30$0^{\circ}C$, and 40$0^{\circ}C$, respectively. We employed a vibrating sample magnetometer(VSM) to measure the B-H loops showing the saturation magnetifation, coercivity, remanence in in- plane and out- of- plane modes. In- plane coercivity, perpendicular coercivity, and perpendicular remanence increased as substrate temperature increased, how-ever they decreased after 30$0^{\circ}C$ slowly. Transmission electron microscope (TEM) characterization revealed that the self organized nano structure (SONS) appears at the elevated substrate temperature, which forms fine Co-enriched phases inside a grain, then it eventually affect the perpendicular magnetic property. Our results imply that we may tune the perpendicular magnetic properties with SONS obtained at appropriate substrate temperature.

Co/Ni 복합실리사이드의 메탈 콘택 건식식각 안정성 연구

송오성,범성진,김득중,Song Ohsung,Beom Sungjin,Kim Dugjoong 한국재료학회 2004 한국재료학회지 Vol.14 No.8

Newly developed silicide materials for ULSI should have the appropriate electrical property of low resistant as well as process compatibility in conventional CMOS process. We prepared $NiCoSi_x$ silicides from 15 nm-Co/15 nm-Ni/Si structure and performed contact dry etch process to confirm the dry etch stability and compatibility of $NiCoSi_x$ layers. We dry etched the photoresist/SiO/silicide/silicon patterns with $CF_4\;and\;CHF_3$ gases with varying powers from 100 to 200 W, and pressures from 45 to 65 mTorr, respectively. Polysilicon and silicon active layers without silicide were etched $0\sim316{\AA}$ during over etch time of 3min, while silicon layers with proposed $NiCoSi_x$ silicide were not etched and showed stable surfaces. Our result implies that new $NiCoSi_x$ silicides may replace the conventional silicides due to contact etch process compatibility.

천연수정의 자기적 특성과 미세구조에 의한 품질평가

송오성,이기영,이정임 한국산학기술학회 2003 한국산학기술학회논문지 Vol.4 No.1

자수정은 우리나라에서 산출되어 수출시장이 큰 준보석이다. 원석을 가공하여 최종 장신구제품을 제작하는데 실제 원석에서는 연수정, 자수정, 백수정이 함께 산출되어 이들의 품위를 정량적으로 평가하여 원석가격을 산출하는 것과 아직 확보되진 않은 자수정의 정량적 감정 기술이 필요하다. 이제까지는 아쉽게도 육안 판별과 경험에 의존하였으나 투과진자 현미경과 선동시편자력계측정을 통하여 3가지 원석의 특성을 명확히 구별하는 것이 가능하였다. 또한 FTIR(Fourier transformation infra-red) 측정을 통하여 고가 자수정의 정량품질 확인도 가능하였다. 이러한 방법은 원석의 품위를 확인하는데 효과적이고 최초 원석 상태에서의 고가 자수정의 함량을 평가할 수 있는 우수한 지표가 될 수 있었다. Amethyst is a precious stone in Korea. As natural quartz are usually mixed with smoky quartz, amethyst, and milky quartz, we need to evaluate the amount of the amethyst quantitatively in ores. Although the optical evaluation with bare eyes has been common in assay so far, we propose that the diamagnetic property and microstructural difference characterization he the solution for the evaluating the quartz ores. In addition, FTIR (Fourier transformation infra-red) could help to identify the amethyst transparency. We report that we could evaluate the amethyst quantitativley with M-H hysteresis characlerization, transmission electron microscopy (TEM) observation and FTIR characterization.

아몰퍼스실리콘의 결정화에 따른 복합티타늄실리사이드의 물성변화

송오성,김상엽,Song Oh-Sung,Kim Sang-Yeob 한국마이크로전자및패키징학회 2006 마이크로전자 및 패키징학회지 Vol.13 No.1

반도체 메모리 소자의 스피드 향상을 위해 저저항 배선층을 채용하는 방안으로 70 nm-두께의 아몰퍼스실리콘과 폴리실리콘 기판부에 $TiSi_2$ 타켓으로 각각 80 nm 두께의 TiSix 복합실리콘을 스퍼터링으로 증착한 후 RTA $800^{\circ}C$-20sec 조건으로 실리사이드화 처리하고 사진식각법으로 선폭 $0.5{\mu}m$의 배선층을 만들었다. 배선층에 대해 다시 각각 $750^{\circ}C-3hr,\;850^{\circ}C-3hr$의 부가적인 안정화 열처리를 실시하였으며, 이때의 면저항의 변화는 four-point probe로 실리사이드층의 미세구조와 수직단면 두께 변화를 주사전자현미경과 투과전자현미경으로 관찰하였다. 아몰퍼스실리콘 기판인 경우 후속열처리에 따른 결정화 진행과 함께 급격한 면저항의 증가가 확인되었고, 이 원인은 결정화 과정에서 실리콘과 복합티타늄실리사이드 층과의 상호확산으로 표면 공공(void)을 형성한 것으로 미세구조 관찰에서 확인되었다. 따라서 복합티타늄실리사이드의 하지층의 종류와 열처리 조건을 바꾸어 저저항 또는 고저항 실리사이드를 조절하여 제작하는 것이 가능하여 복합 $TiSi_2$를 저저항 배선층 재료로 채용할 수 있음을 확인하였다. We prepared 80 nm-thick TiSix on each 70 nm-thick amorphous silicon and polysilicon substrate using an RF sputtering with $TiSi_2$ target. TiSix composite silicide layers were stabilized by rapid thermal annealing(RTA) of $800^{\circ}C$ for 20 seconds. Line width of $0.5{\mu}m$ patterns were embodied by photolithography and dry etching process, then each additional annealing process at $750^{\circ}C\;and\;850^{\circ}C$ for 3 hours was executed. We investigated the change of sheet resistance with a four-point probe, and cross sectional microstructure with a field emission scanning electron microscope(FE-SEM) and transmission electron microscope(TEM), respectively. We observe an abrupt change of resistivity and voids at the silicide surface due to interdiffusion of silicide and composite titanium silicide in the amorphous substrates with additional $850^{\circ}C$ annealing. Our result implies that the electrical resistance of composite titanium silicide may be tunned by employing appropriate substrates and annealing condition.

A Study on Thermodynamics for Compositional Separation in Co-Cr magnetic Alloy Films

송오성,전전안,Song, O-Seong,Jeon, Jeon-An Materials Research Society of Korea 1999 한국재료학회지 Vol.9 No.4

We reported compositional separation(CS) into Co-enriched and Cri-enriched components inside the grains of Co-Cr based thin films prepared by rf sputtering. CS strongly depends on the sputtering conditions of substrate temperature and target composition. Tuning the microstructure of the Co-Cr films is important in order to employ the CS for high-density magnetic recording. We investigated the origin of CS from thermodynamic viewpoint. We employ a spinodal decomposition-like model to describe the origin of the CS in Co-Cr films. We consider the total free energy of the Co-Cr films as the sum of several free energies of; 1) thermodynamic mixing entropy of a binary solid solution, 2) magnetic ordering interaction(MOI) energy below the Curie temperature, and 3) excess interaction energy(XS) caused by the sputtering process as a function of temperature and composition. Those energies distorted the total free energy like the spinodal decomposition and caused the compositionally separated fine microstructure inside the grains. If the second derivative of the total free energy with respect to Cr composition becomes negative at a given substrate temperature, we may observe a metastable compositional separation inside the Co-Cr alloy films. We expect to exploit the microstructure of CS for ultra-high density magnetic recording.

코발트 니켈 합금 구조에서 생성된 실리사이드의 마이크로 핀홀의 발생

송오성,김상엽,전장배,김문제,Song, Oh-Sung,Kim, Sang-Yeob,Jeon, Jang-Bae,Kim, M.J. 한국재료학회 2006 한국재료학회지 Vol.16 No.10

We fabricated thermal evaporated 10 nm-$Ni_xCo_{1-x}$ (x=0.2, 0.5 and 0.8) /(poly)Si films to form nanothick cobalt nickel composite silicides by a rapid thermal annealing at $700{\sim}1100^{\circ}C$ for 40 seconds. A field emission scanning electron microscope and a micro-Raman spectrometer were employed for microstructure and silicon residual stress characterization, respectively. We observed self-aligned micro-pinholes on single crystal silicon substrates silicidized at $1100^{\circ}C$. Raman silicon peak shift indicates that the residual tensile strain of $10^{-3}$ in single crystal silicon substrates existed after the silicide process. We propose thermal stress from silicide exothermic reaction and high temperature silicidation annealing may cause the pinholes. Those pinholes are expected to be avoided by lowering the silicidation temperature. Our results imply that we may use our newly proposed composite silicides to induce the appropriate strained layer in silicion substrates.