• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2005.07a
• /
• pp.649-650
• /
• 2005

반도체는 고집적화, 고속도화, 저전력화를 목적으로 발전하고 있다. 이를 위하여 design rule의 감소, 새로운 물질과 프로세스의 적용 등 많은 연구가 이루어지고 있으며, RC delay time을 줄이기 위한 Cu 와 저유전율 재료의 적용이 그 대표적인 예라 할 수 있다. Cu 배선은 기존의 Al 배선에 비하여 높은 전자이동 (electro-migration)과 응력 이동 (stress-migration) 저항을 가짐으로써 전기적인 성능 (electrical performance) 에서 이점을 가지고 있다. 반도체에서의 Cu 배선 구조는 평탄화된 표면 및 배선들 사이에서의 좋은 전기적인 절연성을 가져야 하며, 이는 디싱(dishing)과 에로젼(erosion)의 중요한 인자가 된다. 기존의 평탄화 공정인 Cu CMP(Chemical Mechanical Polishing)에 있어서 이러한 디싱, 에로전과 같은 결함은 선결되어져야 할 문제로 인식되고 있다. 따라서 본 연구에서는 이러한 결합들을 감소시키기 위한 새로운 평탄화 방법으로 Cu gap-filling 을 하는 동시에 평탄화된 표면을 이루는 ECMD(Electro-Chemical Mechanical Deposition) 공정의 전기적 기계적 특성을 파악하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.07a
• /
• pp.874-877
• /
• 2001

SOI(Silicon-On-Insulator) technology is proposed as an alternative to bulk silicon for MEMS(Micro Electro Mechanical System) manufacturing. In this paper, we fabricated the SOI wafer with uniform active layer thickness by silicon direct bonding and mechanical polishing processes. Specially-designed electrostatic bonding system is introduced which is available for vacuum packaging and silicon-glass wafer bonding for SOG(Silicon On Glass) wafer. We demonstrated thermopile sensor and RF resonator using the SOI wafer, which has the merits of simple process and uniform membrane fabrication.

• Proceedings of the KIEE Conference
• /
• 2001.07c
• /
• pp.1369-1371
• /
• 2001

This paper describes on thinning SDB SOI substrates by SDB technology and Electro-chemical etch-stop. The surface of the fabricated SDB SOI substrates is more uniform than that grinding or polishing by mechanical method, and this process is possible to accurate SOI thickness control. During Electrochemical etch-stop, leakage current versus voltage curves were measured for analysis of the open current potential (OCP) point and the passivation potential (PP) poin and determinated to anodic passivation potential. The surface roughness and selectively controlled thickness of the fabricated SOI substrates were analyzed by using AFM and SEM, respectively.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.20 no.1
• /
• pp.86-95
• /
• 2011

Ultra-precision machining technology is the essential core technology in today's micro-electronics and electro-optical industries. The needs for processing systems to manufacture products to nanometer(nm) accuracy and sub-nanometer resolutions are increased recently. By using ion beam, it is possible to fabricate ultra-precision and ultra-fine products with nm accuracy and sub-nm resolution. In this paper, the basic research trends of ultra precision machining technology in domestic are surveyed, and the ways to reach to the world-leading level of basic research capabilities in the field of ultra-precision machining technology in domestic is suggested.

• Proceedings of the KSME Conference
• /
• 2000.04a
• /
• pp.792-796
• /
• 2000

With the development of micro machining, it becomes an important part to fabricate an electrode which has tens of ${\mu}m$ or less. There are two methods to get a narrow hole; non-contact type such as EDM(Electro-discharge machining) and contact type such as punching. A punch which has a tapered shape with a cylindrical tip is fabricated in this paper. To make this punch, a method which was used to fabricate a cylindrical shape by electrochemical process was applied. The control factors for the shape and their limits are verified through an experiment.

• Proceedings of the KSME Conference
• /
• 2008.11a
• /
• pp.311-316
• /
• 2008

Thick-walled cylinders, such as a cannon or nuclear reactor, are autofrettaged to induce advantageous residual stresses into pressure vessels and to increase operating pressure and the fatigue lifetimes. As the autofrettage level increases, the magnitude of compressive residual stress at the bore also increases. The purpose of the present paper is to predict the accurate residual stress of SCM440 high strength steel using the Kendall model which was adopted by ASME Code. Hydraulic pressure process was applied and thick-walled cylinders were autofrettaged up to 30% overstrain levels. Electro polishing was performed to get more accurate data. Residual stresses were measured by X-ray diffraction method. The autofrettaged surface which was plastically deformed analyzed using a scanning electron microscope(SEM). Although there were some differences in measured residual stress and numerical, there is a tendency to agree.

• Journal of the Korean Ceramic Society
• /
• v.34 no.10
• /
• pp.1092-1098
• /
• 1997

Electrical discharge machining (EDM) was attempted on a ceramic matrix composite containing non-conductive alumina as a matrix and conductive titania as a second phase, and was found successful. As the current or duty factor increased, the material removal rate (MRR) increased and the surface roughness also increased. The EDMed surface was covered with a number of craters of a circular shape having 100-200 microns of diameter. The melting and evaporation was suggested for the EDM mechanism. The bending strength decreased 44% after EDM, but the Weibull modulus increased more than twice. Combination of EDM and barre이 polishing resulted in the maintenance of the bending strength level. Temperature distribution near a spark in the sample was computer-simulated by use of finite element method, and was found to have similar shape to the one which the observed craters have.

• Journal of Integrative Natural Science
• /
• v.7 no.1
• /
• pp.1-4
• /
• 2014

Distributed Bragg reflector porous silicon of different characteristics were formed to determine their optical constants in the visible wavelength range using a periodic square wave current between low and high current densities. The surface and cross-sectional SEM images of distributed Bragg reflector porous silicon were obtained using a cold field emission scanning electron microscope. The surface image of distributed Bragg reflector porous silicon indicates that the distributions of pores are even. The cross-sectional image illustrates that the multilayer of distributed Bragg reflector porous silicon exhibits a depth of few microns and applying of square current density during the etching process results two distinct refractive indices in the contrast. Distributed Bragg reflector porous silicon exhibited a porosity depth profile that related directly to the current-time profile used in etch. Its free-standing film was obtained by applying an electro-polishing current.

• Journal of the Korean Electrochemical Society
• /
• v.10 no.2
• /
• pp.94-103
• /
• 2007

The transition of interconnection metal from aluminum alloy to copper has been introduced to meet the requirements of high speed, ultra-large scale integration, and high reliability of the semiconductor device. Since copper, which has low electrical resistivity and high resistance to degradation, has different electrical and material characteristics compared to aluminum alloy, new related materials and processes are needed to successfully fabricate the copper interconnection. In this review, some important factors of multilevel copper damascene process have been surveyed such as diffusion barrier, seed layer, organic additives for bottom-up electro/electroless deposition, chemical mechanical polishing, and capping layer to introduce the related issues and recent research trends on them.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.08a
• /
• pp.319-320
• /
• 2012

Large aperture optical modulator called optical shutter is a key component to realize time-of-flight (TOF) based three dimensional (3D) imaging systems [1-2]. The transmission type electro-absorption modulator (EAM) is a prime candidate for 3D imaging systems due to its advantages such as small size, high modulation performance [3], and ease of forming two dimensional (2D) array over large area [4]. In order to use the EAM for 3D imaging systems, it is crucial to remove GaAs substrate over large area so as to obtain high uniformity modulation performance at 850 nm. In this study, we propose and experimentally demonstrate techniques for backside etching of GaAs substrate over a large area having high uniformity. Various methods such as lapping and polishing, dry etching for anisotropic etching, and wet etching ([20%] C6H8O7 : H2O2 = 5:1) for high selectivity backside etching [5] are employed. A high transmittance of 80% over the large aperture area ($5{\times}5mm^2$) can be obtained with good uniformity through optimized backside etching method. These results reveal that the proposed methods for backside etching can etch the substrate over a large area with high uniformity, and the EAM fabricated by using backside etching method is an excellent candidate as optical shutter for 3D imaging systems.