• Title, Summary, Keyword: Photoresist

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Dry Etching of PMMA and Polycarbonate in a Diffusion Pump-based Capacitively Coupled O2 Plasma (확산펌프 기반의 O2 축전결합 플라즈마를 이용한 PMMA와 폴리카보네이트의 건식 식각)

  • Park, Ju-Hong;Lee, Seong-Hyun;Choi, Jyoung-Hoon;Noh, Ho-Sub;Lee, Je-Won
    • Korean Journal of Materials Research
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    • v.19 no.8
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    • pp.421-426
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    • 2009
  • We report on the capacitively coupled O2 plasma etching of PMMA and polycarbonate (PC) with a diffusion pump. Plasma process variables were process pressure and CCP power at 5 sccm $O_2$ gas flow rate. Characterization was done in order to analyze etch rate, etch selectivity, surface roughness, and morphology using stylus surface profilometry and scanning electron microscopy. Self bias decreased with increase of process pressure in the range of 25$\sim$180 mTorr. We found an important result for optimum pressure for the highest etch rate of PMMA and PC, which was 60 mTorr. PMMA and PC had etch rates of 0.46 and 0.28 ${\mu}m$/min under pressure conditions, respectively. More specifically, etch rates of the materials increased when the pressure changed from 25 mTorr to 60 mTorr. However, they reduced when the pressure increased further after 60 mTorr. RMS roughnesses of the etched surfaces were in the range of 2.2$\sim$2.9 nm. Etch selectivity of PMMA to a photoresist was $\sim$1.5:1 and that of PC was $\sim$0.9:1. Etch rate constant was about 0.04 ${\mu}m$/minW and 0.02 ${\mu}m$/minW for PMMA and PC, respectively, with the CCP power change at 5 sccm $O_2$ and 40 mTorr process pressure. PC had more erosion on the etched sidewall than PMMA did. The OES data showed that the intensity of the oxygen atomic peak (777.196 nm) proportionally increased with the CCP power.

Etch Characteristics of CoTb and CoZrNb Thin Films by High Density Plasma Etching (고밀도 플라즈마 식각에 의한 CoTb과 CoZrNb 박막의 식각 특성)

  • Shin, Byul;Park, Ik Hyun;Chung, Chee Won
    • Korean Chemical Engineering Research
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    • v.43 no.4
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    • pp.531-536
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    • 2005
  • Inductively coupled plasma reactive ion etching of CoTb and CoZrNb magnetic materials with the photoresist mask was performed using $Cl_2/Ar$ and $C_2F_6/Ar$ gas mixtures and characterized in terms of etch rate and etch profile. As the concentrations of $Cl_2$ and $C_2F_6$ gases increased, the etch rates of magnetic films decreased and the etch slopes became slanted. The $Cl_2/Ar$ gas was more effective in obtaining fast etch rate and steep sidewall slope than the $C_2F_6/Ar$ gas. As the coil rf power and dc bias increased, fast etch rate and steep etch slope were obtained but the redeposition on the sidewall was observed. This is due to the increase of ion and radical densities in plasma with increasing the coil rf power and the increase of incident ion energy to the substrate with increasing the dc bias voltage. By applying high density reactive ion etching to magnetic tunnel junction stack containing various magnetic films and metal oxide, steep etch slope and clean etch profile without redeposition were obtained.

Effect of Contact Angles of PDMS and External Voltage on Flow Velocity in Microchannel (PDMS의 접촉각 및 외부전압 변화에 따른 마이크로채널에서 유체의 속도변화)

  • Lee, Hyo-Song;Kim, Jin-Yong;Kim, Jeong-Soo;Rhee, Young Woo
    • Korean Chemical Engineering Research
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    • v.43 no.1
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    • pp.92-97
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    • 2005
  • In this study, the effect of contact angles of PDMS and external voltage has been investigated. SU-8 (Microchem, USA) negative photoresist and PDMS are used to make the microchannel. The contact angle of the native PDMS is $105^{\circ}$. The native PDMS is treated with the oxygen plasma and the contact angle changes $19^{\circ}$, $46^{\circ}$ and $69^{\circ}$. As a result, the rate of increase in flow velocity is not directly proportional to the rate of increase of external voltage. This is because the electrical double layer is condensed and the zeta potential is increased with an increase of the external voltage. The flow velocity is highest for the contact angle of $19^{\circ}$ at the same external voltage. Hence we conclude that the thickness of electrical double layer and flow velocities vary with contact angle at the same external voltage.

Analysis of Coating Uniformity through Unsteady and Steady State Computer Simulation in Slot Coating (슬롯코팅에서 정상 및 비정상상태 컴퓨터해석을 통한 코팅의 균일성 분석)

  • Woo, Jeong-Woo;Sung, Dal-Je;Lyu, Min-Young
    • Polymer(Korea)
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    • v.38 no.5
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    • pp.640-644
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    • 2014
  • As a process of plat panel display production, slot coating is widely used for the coating of photoresist on a wide glass substrate. A uniform coating thickness is important, and the coating uniformity is divided into nozzle and machine directions. The machine and nozzle directions coating uniformities are influenced by the operation condition of coater and flow uniformity inside the die, respectively. Non-uniform coating during steady coating process occurs according to those factors, however, non-uniform coating along the machine and nozzle directions has been observed at the beginning of coating by unsteady flow. In this study, steady and unsteady state flow simulations have been performed and compared with experiment to examine the causes of non-uniform coating. Computational results exhibited that it took a time to get a uniform pressure distribution at whole inside the die, and during this period of time edge regions showed lower exit velocity compared with center region. Subsequently edge regions had thinner coated layers than center region. However edge regions showed higher exit velocity than center region after steady state, and this made edge regions had thicker coated layer than center region.

Synthesis and Characterization of Photosensitive Polyimides Containing Alicyclic Structure (지방족고리 구조를 함유하는 감광성 폴리이미드 수지의 합성 및 특성 평가)

  • 심종천;최성묵;심현보;권수한;이미혜
    • Polymer(Korea)
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    • v.28 no.6
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    • pp.494-501
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    • 2004
  • A new alkali developable photosensitive poly(amic acid) (PAA-0) with transmittance at 400 nm was synthesized from cyclobutane-1,2,3,4-tetracarboxylic dianhydride, 2-(methacryloyloxy)ethyl-3,5-diamino-benzoate and 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyl disiloxane in N-methyl-2-pyrrolidinone. Photosensitivity of the PAA-0 was investigated at 365-400 nm in the presence of a photoinitiator using a high pressure mercury lamp. The photo-cured poly(amic acid) was insoluble toward aqueous 2.38 wt% tetramethylammonium hydroxide solution. Negative pattern of the PAA-0 with 25 ${\mu}{\textrm}{m}$ resolution was obtained by developing with 2.38 wt% tetramethylammonium hydroxide solution after exposure of 600 mJ/$\textrm{cm}^2$ in the presence of 2,2-dimethoxy-2-phenyl-acetophenone as a photoinitiator. The patterned poly(amic acid) was converted to polyimide by thermal curing at 25$0^{\circ}C$ for 50 min, which showed chemical resistance against photoresist stripper as well as good transmittance at 400 nm.

Improvement of Optical Characteristics in Viewing Directions in a Reflective Cholesteric Liquid Crystal Color Filter (반사형 콜레스테릭 칼라필터의 시야각에 따른 광특성 향상에 관한 연구)

  • Kim, Tae-Hyun;Lim, Young-Jin;Hwang, Seong-Jin;Lee, Myong-Hoon;Jang, Won-Gun;Lee, Seung-Hee
    • Polymer(Korea)
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    • v.31 no.2
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    • pp.148-152
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    • 2007
  • The prototype of color fitters for the liquid crystal displays (LCD) using cholesteric liquid crystal monomers was produced. Cholesteric liquid crystal is characterized by the unique optical features of selective reflection, which is due to the helical twisting structures of LCs comparable to the wavelength of the incident light under certain conditions of substrate treatment. In the results of the experiment, cholesteric films for red, green, and blue light reflections respectively were produced and the viewing angle dependence of these films were investigated. Reflective light of red and green films shifted to shorter wavelength regions as viewing angle becomes greater, but blue one shifted very little. Periodic micrometer-sized half-spherical photoresist formed by thermal reflow method after photo-lithography was patterned on glass substrates. The viewing angle dependence of reflective light colors of red, green, and blue films on the patterned substrates compared with those on no patterned substrates was investigated. We could confirm the dependences were much smaller on the patterned substrates by bare eyes and Lab-color coordination methods qualitatively.

Variation of Flow Rates in Heterogeneous Microchannel Systems (비균일계 마이크로채널에서의 유량 변화 특성)

  • Kim, Jin-Yong;Lee, Hyo-Song;Yu, Jae-Keun;Kim, Ki-Ho;Rhee, Young Woo
    • Applied Chemistry for Engineering
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    • v.17 no.1
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    • pp.28-32
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    • 2006
  • This study investigated the variation of flow rates in microchannels that consisted of polydimethyl siloxane (PDMS) and glass using various external voltages. Three different microchannel widths and two different depths. PDMS and negative photoresist (SU-8) were used to make the microchannels by the soft lithographic method. For each depth of microchannel ($50{\mu}m$ and $100{\mu}m$), three different widths ($100{\mu}m$, $200{\mu}m$ and $300{\mu}m$) were made. In each case, several different external voltages were applied (0.3 kV, 0.35 kV, 0.4 kV and 0.45 kV) to examine the flow rates. Our results indicated that flow rate increased with an increase of the external voltage at the same microchannel width. This was because the electrical field was increased as the external voltage increased. For the same external voltage, the flow rate increased as the microchannel's width increased. These results showed that the resistance in the microchannel decreased as the microchannel's width increased. Also, to investigate the effect of microchannel's depth and width, the cross-sectional area of the microchannel was increased to the double in area. As a result, the effect of the microchannel's depth was higher at a low external voltage, and the effect of the microchannel's width was higher at a high external voltage.

Characteristics of MHEMT Devices Having T-Shaped Gate Structure for W-Band MMIC (W-Band MMIC를 위한 T-형태 게이트 구조를 갖는 MHMET 소자 특성)

  • Lee, Jong-Min;Min, Byoung-Gue;Chang, Sung-Jae;Chang, Woo-Jin;Yoon, Hyung Sup;Jung, Hyun-Wook;Kim, Seong-Il;Kang, Dong Min;Kim, Wansik;Jung, Jooyong;Kim, Jongpil;Seo, Mihui;Kim, Sosu
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.33 no.2
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    • pp.99-104
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    • 2020
  • In this study, we fabricated a metamorphic high-electron-mobility transistor (mHEMT) device with a T-type gate structure for the implementation of W-band monolithic microwave integrated circuits (MMICs) and investigated its characteristics. To fabricate the mHEMT device, a recess process for etching of its Schottky layer was applied before gate metal deposition, and an e-beam lithography using a triple photoresist film for the T-gate structure was employed. We measured DC and RF characteristics of the fabricated device to verify the characteristics that can be used in W-band MMIC design. The mHEMT device exhibited DC characteristics such as a drain current density of 747 mA/mm, maximum transconductance of 1.354 S/mm, and pinch-off voltage of -0.42 V. Concerning the frequency characteristics, the device showed a cutoff frequency of 215 GHz and maximum oscillation frequency of 260 GHz, which provide sufficient performance for W-band MMIC design and fabrication. In addition, active and passive modeling was performed and its accuracy was evaluated by comparing the measured results. The developed mHEMT and device models could be used for the fabrication of W-band MMICs.

Dry Etching of Flexible Polycarbonate and PMMA in O2/SF6/CH4 Discharges (O2/SF6/CH4 플라즈마를 이용한 플렉시블 Polycarbonate와 PMMA의 건식 식각)

  • Joo, Y.W.;Park, Y.H.;Noh, H.S.;Kim, J.K.;Lee, J.W.
    • Journal of the Korean Vacuum Society
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    • v.18 no.2
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    • pp.85-91
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    • 2009
  • There has been a rapid progress for flexible polymer-based MEMS(Microelectromechanical Systems) technology. Polycarbonate (PC) and Poly Methyl Methacrylate (PMMA), so-called acrylic, have many advantages for optical, non-toxic and micro-device application. We studied dry etching of PC and PMMA as a function of % gas ratio in the $O_2/SF_6/CH_4$ temary plasma. A photoresist pattern was defined on the polymer samples with a mask using a conventional lithography. Plasma etching was done at 100 W RIE chuck power and 10 sccm total gas flow rate. The etch rates of PMMA were typically 2 times higher than those of PC in the whole experimental range. The result would be related to higher melting point of PC compared to that of PMMA. The highest etch rates of PMMA and PC were found in the $O_2/SF_6$ discharges among $O_2/SF_6$, $O_2/CH_4$ and $SF_6/CH_4$ and $O_2/SF_6/CH_4$ plasma composition (PC: ${\sim}350\;nm/min$ at 5 sccm $O_2/5$ sccm $SF_6$, PMMA: ${\sim}570\;nm/min$ at 2.5 sccm $O_2/7.5$ sccm $SF_6$). PC has smoother surface morphology than PMMA after etching in the $O_2/SF_6/CH_4$ discharges. The surface roughness of PC was in the range of 1.9$\sim$3.88 nm. However, that of PMMA was 17.3$\sim$26.1 nm.