연구

  • 연구실소개

연구실소개

표면공정연구실

Research Description

overview

Our research mainly focuses on etching and deposition of various thin films for the fabrication of microelectronics and microelectromechanical systems (MEMS) devices, nanotechnology,
surface modification of materials, and so on.
Plasma processing and electrochemical methods are used to elucidate fundamental phenomena and mechanisms during etching and deposition of thin films.
The following describes briefly the current research interest.

Atomic Scale Plasma Etching for the Fabrication of Nano-structures As device dimensions keep shrinking below 100 nm, control of film thickness down to atomic level is increasingly required for the fabrication of extremely thin layers used in many devices.
We have developed "Atomic Scale Etching (ASE)" of poly-Si, which can give etching with atomic scale accuracy, in inductively coupled Ar and He plasmas. The process window for the realization of ASE could be obtained by varying ion energy.
Within the process window for ASE, etch rates were found to be self-limited with respect to ion energy, confirming that ASE of poly-Si was obtained at this condition.
The use of a Faraday cage system to measure the angular dependence of etch rates revealed etch mechanisms within and outside the process windows for the realization of ASE.

Mechanism and Chemistry of Deep Si Etching Plasma etching of high aspect ratio features of Si is a key process in the fabrication of Si-based MEMS devices. The Bosch process, which is known as a gas-chopping etching or time-multiplexed etching, is currently in widespread use for deep Si etching. It is a cyclic process, consisting of sequentially alternating etch and deposition steps. To date, most studies on deep Si etching have been confined to the observation of etch characteristics of blank substrate or final etch profiles obtained by changing the process variables. However, these studied do not permit an understanding of the mechanism of this process and an identification of the optimal process conditions required to yield high aspect ratio and anisotropy. During deep Si etching, various phenomena take place simul taneously such as ion-induced etching, chemical etching of the sidewall by reactive radicals, polymer deposition due to radicals, the redeposition of particles emitted from the bottom, and so on.
For better understanding of deep Si etching mechanism, we used a Faraday cage, a specially designed substrate, and sample holders. This allows one to measure individual rates of lateral and vertical etching and the angular dependence of etch rates. Based on these measurements, optimum conditions for bias voltage and source power for each step of the deep Si etching could be proposed, obtaining an anisotropic etch profiles. We have also demonstrated that the use of a Faraday cage combined with a high bias voltage in the etching step produced an etch profile combined with a high bias voltage in the etching step produced an etch profile Currently, SF and C₄F are mainly used in the etching and deposition steps of the deep Si etching, respectively. However, CF is perfluoro carbon (PFC), which is considered to be problematic from an environmental point of view because of its long atmospheric lifetime, high global warming potential, and strong infrared absorption. In order to reduce PFC emission during deep Si etching, we developed alternative chemistries to PFC for deep Si etching.
Based on understanding of the characteristics of fluorocarbon films produced in PFC and non-PFC plasmas, highly anisotropic Si etching can be successfully achieved in both PFC and non-PFC plasmas.
Electro and Electroless Deposition of capping/barrier Layers for Cu Interconnection The use of copper for wiring in the fabrication of microelectronic devices and MEMS has some advantages over aluminum wiring such as low electrical resistance, higher allowed current density, good reliability, and higher electromigration resistance. Major drawbacks for copper metallization, however, are its oxidation and diffusion into oxide layers, which degrade the performance of the devices.
To prevent copper from oxidation and diffusion, barrier/capping layers have been introduced.
Among them, composite films in the form of iron group metal-refractory metal-P(or B) have been found very promising.
We have developed baths for electrodeposition of CoWP and NiMoP as capping/barrier layers for Cu interconnection. Electrochemical studies (using voltammetry and chronoamperometry) were carried out to find out a rate-determining step and nucleation mechanism for the deposition of CoWP and NiMoP films. The investigation of the effects of process variables (such as electrolyte concentration, PH, temperature, etc.) on thickness, composition, and microstructure of the films could explain chemical and physical behaviors of the films.
CoWP and NiMoP films were also deposited by an electroless plating method using alkali metal-free electrolytes. Due to unique characteristic of electroless plating, electrolessly deposited CoWP and NiMop films showed interesting results.
CoWP films can also be useful for other technological applications since Co-based alloy have good magnetic, physical, and mechanical properties. We investigated coating properties of CoWP films and find out that hardness and corrosion resistance of the CoWP films could be greatly improved, compared to Cr coating.

지도교수 소개
  • 교수명 : 김 창구 (Chang-Koo Kim)
  • 직위 : 아주대학교 화학공학과 교수
  • 연구실 위치 : 서관202호
  • 연락처 (교내) : 031-219-2389
    (FAX) : 031-219-1612
  • E-mail : changkoo@ajou.ac.kr

  • 학력(기간)
    • 1988.3~1992.2 : 서울대학교 화학공학과(학사)
    • 1992.3~1995.8 : 서울대학교 화학공학과(석사)
    • 1996.8~2000.12 : Department of Chemical Engineering University of Houston(Ph.D)
  • 경력(기간)
    • 2001.1~2002.2 : Senior process engineer. Novellus (San Jose ,CA)
    • 2002.3~2006.2 : 아주대학교 조교수
    • 2006.3~2011.2 : 아주대학교 부교수    
    • 2011.3~현재   : 아주대학교 교수
연구분야
  • Atomic Scale Plasma Etching for the Fabrication of Nano-structures
  • Mechanism and Chemistry of Deep Si Etching
  • Electro and Electroless Deposition of capping/barrier Layers for Cu Interconnection
연구성과

논문실적 (SCI, 2002년 이후

  • 1.S. M. S. I. Dulal, Hyeong Jin Yun, Chee Burm Shin, and Chang-Koo Kim, "Electrodeposition of CoWP film V. Structural and morphological characteristics", Applied Surface Science, in press.
  • 2. Chijung Kim, Donghun Jeong, Jinha Hwang, Heeyeop Chae, and Chang-Koo Kim, "Argon and nitrogen plasma surface treatments of polyimide films for electroless copper plating", Journal of Korean Physical Society, in press.
  • 3. Sang Ho Woo, Yil Wook Kim, Pyung Yong Um, Hae-Min Lee, and Chang-Koo Kim, "Film Properties of Nitrogen-Doped Polycrystalline Silicon for Advanced Gate Material", Korean Journal of Chemical Engineering, in press.
  • 4. Hyongmoo Rhee, Hae Min Lee, Yun Mi Namkoung, Chang-Koo Kim, Heeyeop Chae, and Yil Wook Kim, "Dependence of Etch Rates of Silicon Substrates on the Use of C4F8 and C4F6 Plasmas in the Deposition Step of the Bosch Process", Journal of Vacuum Science and Technology B, 27 (1), pp.33-40 (2009, Jan.).
  • 5. S. M. S. I. Dulal, Tae Ho Kim, Hyongmoo Rhee, Joon Yong Sung, and Chang-Koo Kim, "Development of an alkali-metal-free bath for electroless deposition of Co-W-P capping layers for copper interconnections", Journal of Alloys and Compounds, 467 (1-2), pp.370-375 (2009, Jan.).
  • 6. Hyeong Jin Yun, S. M. S. I. Dulal, Chee Burm Shin, and Chang-Koo Kim, "Characterisation of electrodeposited Co-W-P amorphous coatings on carbon steel", Electrochimica Acta, 54 (2), pp.370-375 (2008, Dec.).
  • 7. S. M. S. I. Dulal, Tae Ho Kim, Chee Burm Shin, and Chang-Koo Kim, "Electrodeposition of CoWP film IV. Effect of applied potential and current density", Journal of Alloys and Compounds, 461 (1-2), pp.382-388 (2008, Aug.).
  • 8. John Kiran Anthony, Hee Cheoul Kim, Hwang Woon Lee, S. Kumar Mahapatra, Hae Min Lee, Chang-Koo Kim, Kihong Kim, Hanjo Lim, and Fabian Rotermund, "Particle size-dependent giant nonlinear absorption in nanostructured Ni-Ti alloys", Optics Express, 16 (15), pp.11193-11202 (2008, Jul.).
  • 9. Tae Ho Kim, S. M. S. I. Dulal, Chang Han Park, Heeyeop Chae, and Chang-Koo Kim, "Optimisation of process parameters for electroless plating of Co-W-P capping layers from an alkali-metal-free bath", Surface & Coatings Technology, 202 (19), pp.4861-4867 (2008, Jun.).
  • 10. Hyongmoo Rhee, Hyeokkyu Kwon, Chang-Koo Kim, HyunJung Kim, Jaisuk Yoo, and Yil Wook Kim, "Comparison of deep silicon etching using SF6/C4F8 and SF6/C4F6 plasmas in the Bosch process", Journal of Vacuum Science and Technology B, 26 (2), pp.576-581 (2008, Mar.).
  • 11. S. M. S. I. Dulal, Chee Burm Shin, Joon Yong Sung, and Chang-Koo Kim, "Electrodeposition of CoWP film II. Effect of electrolyte concentration", Journal of Applied Electrochemistry, 38 (1), pp.83-91 (2008, Jan.).
  • 12. S. M. S. I. Dulal, Hyeong Jin Yun, Chee Burm Shin, and Chang-Koo Kim, "Electrodeposition of CoWP film III. Effect of pH and temperature", Electrochimica Acta, 53 (2), pp.934-943 (2007, Dec.).
  • 13. S. M. S. I. Dulal, Hyeong Jin Yun, Chee Burm Shin, and Chang-Koo Kim, "Electrodeposition of CoWP Film I. Electrochemical and Compositional Analyses", Journal of Electrochemical Society, 154 (10), pp.D494-D501 (2007, Oct.).
  • 14. Sungi Jang, Heeyeop Chae, Donggeun Jung, Hyoungsub Kim, and Chang-Koo Kim, "Simultaneous Oxygen Plasma and Thermal Treatments of an ITO Surface to Improve the Electrical Characteristics of Organic Light-Emitting Diodes", Journal of Korean Physical Society, 51 (3), pp.956-962 (2007, Sep.).
  • 15. Hyeong Jin Yun, Tae Ho Kim, Chee Burm Shin, Chang-Koo Kim, Jae-Ho Min, and Sang-Heup Moon, "A Comparative Study on Atomic Scale Etching of Poly-Si in Inductively Coupled Ar and He Plasmas", Korean Journal of Chemical Engineering, 24 (4), pp.670-673 (2007, Aug.).
  • 16. Hyun-Kyu Ryu, Yil-Wook Kim, Kangtaek Lee, Chee Burm Shin, and Chang-Koo Kim, "A Comparative Study on a High Aspect Ratio Contact Hole Etching in UFC-containing and PFC-containing Plasmas", Microelectronics Journal, 38 (1), pp.125-129 (2007, Jan.)
  • 17. Jae-Ho Min, Jin-kwan Lee, Sang Heup Moon, and Chang-Koo Kim, "Interactive Relationships between Sidewall and Bottom Etch Rates, As-affected by Sidewall angle, during SiO2 Etching in a CHF3 Plasma", Journal of Vacuum Science and Technology B, 24 (4), pp.1746-1754 (2006).
  • 18. Hyun-Kyu Ryu, Yil-Wook Kim, Kangtaek Lee, Chee Burm Shin, and Chang-Koo Kim, "Effect of Wafer Cleaning on the Interconnect Structure and Its Electrical Properties during the Al Dual Damascene Process for the Fabrication of Sub-100 nm Memory Devices", Journal of Chemical Engineering of Japan, 38 (11), pp.922-928 (2005).
  • 19. Jae-Ho Min, Jin-kwan Lee, Sang Heup Moon, and Chang-Koo Kim, "Deep Etching of Silicon with Smooth Sidewalls by an Improved Gas-Chopping Process Using a Faraday Cage and a High Bias Voltage", Journal of Vacuum Science and Technology B, 23 (4), pp.1405-1411 (2005).
  • 20. Jae-Ho Min, Gyeo-Re Lee, Jin-kwan Lee, Sang Heup Moon, and Chang-Koo Kim, "Effect of Sidewall Properties on the Bottom Microtrench during SiO2 Etching in a CF4 Plasma", Journal of Vacuum Science and Technology B, 23 (2), pp.425-432 (2005).
  • 21. Chang-Koo Kim and Chee Burm Shin, "Plasma Molding over Surface Topography: Measurement of Energy and Angular Distributions of Ions Extracted through a Large Hole", Thin Solid Films, 475 (1-2), pp.24-31 (2005).
  • 22. Jae-Ho Min, Gyeo-Re Lee, Jin-kwan Lee, Chang-Koo Kim, and Sang Heup Moon "Improvement of SiO2 Pattern Profiles Etched in CF4 and SF6 Plasmas by Using a Faraday Cage and Neutral Beams", Surface and Coatings Technology, 193 (1-3), pp.75-80 (2005).
  • 23. Chang-Koo Kim, "Ion Dynamics in Plasma Processing for the Fabrication of Ultrafine Structures", Korean Journal of Chemical Engineering, 22 (5), pp.762-769 (2005).
  • 24. . Zhijian Wu, Hyeonwoo Joo, Ik-Sung Ahn, Jung-Hyun Kim, Chang-Koo Kim, and Kangtaek Lee, "Design of Doped Hybrid Xerogels for a Controlled Release of Brillant Blue FCF", Journal of Non-Crystalline Solids, 342, pp.46-53 (2004).
  • 25. Jae-Ho Min, Gyeo-Re Lee, Jin-kwan Lee, Sang Heup Moon, and Chang-Koo Kim, "Angular Dependence of Etch Raes in the Etching of Poly-Si and Fluorocarbon Polymer Using SF6, C4F8, and O2 Plasmas", Journal of Vacuum Science and Technology A, 22 (3), pp.661-669 (2004).
  • 26. Jae-Ho Min, Gyeo-Re Lee, Jin-kwan Lee, Sang Heup Moon, and Chang-Koo Kim, "Dependences of Bottom and Sidewall Etch Rates on Bias Voltage and Source Power during the Etching of Poly-Si and Fluorocarbon Polymer Using SF6, C4F8, and O2 Plasmas", Journal of Vacuum Science and Technology B, 22 (3), pp.893-901 (2004).
  • 27. Chang-Koo Kim, "Analysis of Langmuir Probe Data in High Density Plasmas", Korean Journal of Chemical Engineering, 21 (3), pp.746-751 (2004).
  • 28. Hyun-Kyu Ryu, Byung-Seok Lee, Sung-Ki Park, Il-Wook Kim, and Chang-Koo Kim, "Effect of CH2F2 Addition on a High Aspect Ratio Contact Hole Etching in a C4F6/O2/Ar Plasma", Electrochemical and Solid-State Letters, 6 (9), pp.C126-C129 (2003).
  • 29. Jung-Hyun Ryu, Byeong-Ok Cho, Sung-Wook Hwang, Sang Heup Moon, and Chang-Koo Kim, "Trajectories of Ions inside Faraday Cage Located in a High Density Plasma Etcher", Korean Journal of Chemical Engineering, 20 (2), pp.407-413 (2003).
  • 30. Chang-Koo Kim and Demetre J. Economou, "Plasma Molding over Surface Topography : Energy and Angular Distribution of Ions Extracted out of Large Holes", Journal of Applied Physics, 91 (5), pp.2594-2603 (2002).
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