O, Gwang-Sik;Kim, Dong-Jin;Kim, Jin-Seop;Lee, Jeong-Hui;Lee, Yong-Hyeon;Lee, Jae-Sin;Han, Seok-Yong
Journal of the Institute of Electronics Engineers of Korea SD
/
v.37
no.2
/
pp.13-21
/
2000
Au-black for the application of the long wavelength infrared absorber has been prepared by evaporating Au under nitrogen gas-filled low vacuum condition. Characteristics of the deposited Au-black were carefully investigated through structural analysis, infrared absorbance measurement, and patterning of the layer, all of which are dependent on the deposition condition. High density of micro-cavity that trapped infrared were obtained, and infrared absorbance in the wavelength range from 3 $\mu\textrm{g}$ to 14 $\mu\textrm{g}$ was found to be about 90% when the Au-black layer was produced under the deposition condition of mass Per area of about 600 $\mu\textrm{g}$/cm$^{2}$ and chamber pressure of above 1 Torr. Photoresist lift-off process could be performed to pattern the Au-black, of which mass per area was below 900 $\mu\textrm{g}$/cm/ sup 2/. In view of absorbance, heat capacity, and pattern formation, the deposition condition of chamber pressure of about 1 Tow and mass per area of about 600$\mu\textrm{g}$/cm$^{2}$ was most adequate for preparing the Au-black as an infrared absorber.
Journal of the Microelectronics and Packaging Society
/
v.8
no.1
/
pp.33-38
/
2001
We investigate the via-size dependance of as-electroplated- and reflow-bump shapes for realizing both high-density and high-aspect ratio of solder bump. The solder bump is fabricated by subsequent processes as follows. After sputtering a TiW/Al electrode on a 5-inch Si-wafer, a thick photoresist for via formation it obtained by multiple-codling method and then vias with various diameters are defined by a conventional photolithography technique using a contact alinger with an I-line source. After via formation the under ball metallurgy (UBM) structure with Ti-adhesion and Cu-seed layers is sputtered on a sample. Cu-layer and Sn/pb-layer with a competition ratio of 6 to 4 are electroplated by a selective electroplating method. The reflow-bump diameters at bottom are unchanged, compared with as-electroplated diameters. As-electroplated- and reflow-bump shapes, however, depend significantly on the via size. The heights of as-electroplated and reflow bumps increase with the larger cia, while the aspect ratio of bump decreases. The nearest bumps may be touched by decreasing the bump pitch in order to obtain high-density bump. The touching between the nearest bumps occurs during the overplating procedure rather than the reflowing procedure because the mushroom diameter formed by overplating is larger than the reflow-bump diameter. The arrangement as zig-zag rows can be effective for realizing the flip-chip-interconnect bump with both high-density and high-aspect ratio.
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.
Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
/
2008.11a
/
pp.145-145
/
2008
High-k materials have been paid much more attention for their characteristics with high permittivity to reduce the leakage current through the scaled gate oxide. Among the high-k materials, $ZrO_2$ is one of the most attractive ones combing such favorable properties as a high dielectric constant (k= 20 ~ 25), wide band gap (5 ~ 7 eV) as well as a close thermal expansion coefficient with Si that results in good thermal stability of the $ZrO_2$/Si structure. During the etching process, plasma etching has been widely used to define fine-line patterns, selectively remove materials over topography, planarize surfaces, and trip photoresist. About the high-k materials etching, the relation between the etch characteristics of high-k dielectric materials and plasma properties is required to be studied more to match standard processing procedure with low damaged removal process. Among several etching techniques, we chose the inductively coupled plasma (ICP) for high-density plasma, easy control of ion energy and flux, low ownership and simple structure. And the $BCl_3$ was included in the gas due to the effective extraction of oxygen in the form of $BCl_xO_y$ compounds. During the etching process, the wafer surface temperature is an important parameter, until now, there is less study on temperature parameter. In this study, the etch mechanism of $ZrO_2$ thin film was investigated in function of $Cl_2$ addition to $BCl_3$/Ar gas mixture ratio, RF power and DC-bias power based on substrate temperature increased from $10^{\circ}C$ to $80^{\circ}C$. The variations of relative volume densities for the particles were measured with optical emission spectroscopy (OES). The surface imagination was measured by scanning emission spectroscope (SEM). The chemical state of film was investigated using energy dispersive X-ray (EDX).
Journal of the Institute of Electronics Engineers of Korea SC
/
v.48
no.2
/
pp.28-34
/
2011
In previous reports, we investigated a selective assembly method of fabricating single-walled carbon nanotubes (SWCNTs) on a silicon-dioxide ($SiO_2$) surface by using only a photolithographic process. In this paper, we have fabricated field effect transistors (FETs) with SWCNT channels by using the technique mentioned above. Also, we have electrically measured gating effects of these FETs under different source-drain voltages ($V_{SD}$). These FETs have been fabricated for sensor applications. Photoresist (PR) patterns have been made on a $SiO_2$-grown silicon (Si) substrate by using a photolithographic process. This PR-patterned substrate have been dipped into a SWCNT solution dispersed in dichlorobenzene (DCB). These PR patterns have been removed by using aceton. As a result, a selectively-assembled SWCNT channels in FET arrays have been obtained between source and drain electrodes. Finally, we have successfully fabricated 4 FET arrays based on SWCNT-channels by using our simple self-assembly technique.
Journal of the Korean Institute of Electrical and Electronic Material Engineers
/
v.33
no.2
/
pp.99-104
/
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.
Yoon, Su-Jin;Hwang, Jeongwoo;Lee, Myeong-Ju;Kang, Sang-Woo;Kim, Jong-Su;Ku, Zahyun;Urbas, Augustine;Lee, Sang Jun
Proceedings of the Korean Vacuum Society Conference
/
2014.02a
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pp.296-296
/
2014
We investigate experimentally and theoretically the splitting of surface plasmon (SP) resonance peaks under TE- and TM-polarized illumination. The SP structure at infrared wavelength is fabricated with a 2-dimensional square periodic array of circular holes penetrating through Au (gold) film. In brief, the processing steps to fabricate the SP structure are as follows. (i) A standard optical lithography was performed to produce to a periodic array of photoresist (PR) circular cylinders. (ii) After the PR pattern, e-beam evaporation was used to deposit a 50-nm thick layer of Au. (iii) A lift-off processing with acetone to remove the PR layer, leading to final structure (pitch, $p=2.2{\mu}m$; aperture size, $d=1.1{\mu}m$) as shown in Fig. 1(a). The transmission is measured using a Nicolet Fourier-transform infrared spectroscopy (FTIR) at the incident angle from $0^{\circ}$ to $36^{\circ}$ with a step of $4^{\circ}$ both in TE and TM polarization. Measured first and second order SP resonances at interface between Au and GaAs exhibit the splitting into two branches under TM-polarized light as shown in Fig. 1(b). However, as the incidence angle under TE polarization is increased, the $1^{st}$ order SP resonance peak blue-shifts slightly while the splitting of $2^{nd}$ order SP resonance peak tends to be larger (not shown here). For the purpose of understanding our experimental results qualitatively, SP resonance peak wavelengths can be calculated from momentum matching condition (black circle depicted in Fig. 2(b)), $k_{sp}=k_{\parallel}{\pm}iG_x{\pm}jG_y$, where $k_{sp}$ is the SP wavevector, $k_{\parallel}$ is the in-plane component of incident light wavevector, i and j are SP coupling order, and G is the grating momentum wavevector. Moreover, for better understanding we performed 3D full field electromagnetic simulations of SP structure using a finite integration technique (CST Microwave Studio). Fig. 1(b) shows an excellent agreement between the experimental, calculated and CST-simulated splitting of SP resonance peaks with various incidence angles under TM-polarized illumination (TE results are not shown here). The simulated z-component electric field (Ez) distribution at incident angle, $4^{\circ}$ and $16^{\circ}$ under TM polarization and at the corresponding SP resonance wavelength is shown in Fig. 1(c). The analysis and comparison of theoretical results with experiment indicates a good agreement of the splitting behavior of the surface plasmon resonance modes at oblique incidence both in TE and TM polarization.
Proceedings of the Korean Institute of Surface Engineering Conference
/
1999.10a
/
pp.49-49
/
1999
In this study, $Cl_2/BCI_3$ magnetized inductively coupled plasmas (MICP) were used to etch GaN and the effects of magnetic confinements of inductively coupled plasmas on the GaN etch characteristics were investigated as a function of $Cl_2/BCI_3$. Also, the effects of Kr addition to the magnetized $Cl_2/BCI_3$ plasmas on the GaN etch rates were investigated. The characteristics of the plasmas were estimated using a Langmuir probe and quadrupole ma~s spectrometry (QMS). Etched GaN profiles were observed using scanning electron microscopy (SEM). The small addition of $Cl_2/BCI_3$ (10-20%) in $Cl_2$ increased GaN etch rates for both with and without the magnetic confinements. The application of magnetic confinements to the $Cl_2/BCI_3$ inductively coupled plasmas (ICP) increased GaN etch rates and changed the $Cl_2/BCI_3$ gas composition of the peak GaN etch rate from 10% $BCI_3$ to 20% $BCI_3$. It also increased the etch selectivity over photoresist, while slightly reducing the selectivity over $Si0_2$. The application of the magnetic field significantly increased positive $BCI_2{\;}^+$ measured by QMS and total ion saturation current measured by the Langmuir probe. Other species such as CI, BCI, and CI+ were increased while species such as $BCl_2$ and $BCI_3$ were decreased with the application of the magnetic field. Therefore, it appears that the increase of GaN etch rate in our experiment is related to the increased dissociative ionization of $BCI_3$ by the application of the magnetic field. The addition of 10% Kr in an optimized $Cl_2/BCI_3$ condition (80% $Cl_2/$ 20% $BCI_3$) with the magnets increased the GaN etch rate about 60%. More anisotropic GaN etch profile was obtained with the application of the magnetic field and a vertical GaN etch profile could be obtained with the addition of 10% Kr in an optimized $Cl_2/BCI_3$ condition with the magnets.
Kang, Dong-Hyun;Pak, Soo-Kyung;Park, George O.;Hong, Sang-Jeen
Proceedings of the Korean Vacuum Society Conference
/
2012.02a
/
pp.433-433
/
2012
As the requirement in patterning geometry continuously shrinks down, the termination of etch process at the exact time became crucial for the success in nano patterning technology. By virtue of real-time optical emission spectroscopy (OES), etch end point detection (EPD) technique continuously develops; however, it also faced with difficulty in low open ratio etching, typically in self aligned contact (SAC) and one cylinder contact (OCS), because of very small amount of optical emission from by-product gas species in the bulk plasma glow discharge. In developing etching process, one may observe that coupon test is being performed. It consumes costs and time for preparing the patterned sample wafers every test in priority, so the coupon wafer test instead of the whole patterned wafer is beneficial for testing and developing etch process condition. We also can observe that etch open area is varied with the number of coupons on a dummy wafer. However, this can be a misleading in OES study. If the coupon wafer test are monitored using OES, we can conjecture the endpoint by experienced method, but considering by data, the materials for residual area by being etched open area are needed to consider. In this research, we compare and analysis the OES data for coupon wafer test results for monitoring about the conditions that the areas except the patterns on the coupon wafers for real-time process monitoring. In this research, we compared two cases, first one is etching the coupon wafers attached on the carrier wafer that is covered by the photoresist, and other case is etching the coupon wafers on the chuck. For comparing the emission intensity, we chose the four chemical species (SiF2, N2, CO, CN), and for comparing the etched profile, measured by scanning electron microscope (SEM). In addition, we adopted the Dynamic Time Warping (DTW) algorithm for analyzing the chose OES data patterns, and analysis the covariance and coefficient for statistical method. After the result, coupon wafers are over-etched for without carrier wafer groups, while with carrier wafer groups are under-etched. And the CN emission intensity has significant difference compare with OES raw data. Based on these results, it necessary to reasonable analysis of the OES data to adopt the pre-data processing and algorithms, and the result will influence the reliability for relation of coupon wafer test and whole wafer test.
Kim, Jin-Yong;Lee, Hyo-Song;Yu, Jae-Keun;Kim, Ki-Ho;Rhee, Young Woo
Applied Chemistry for Engineering
/
v.17
no.1
/
pp.28-32
/
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.
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