Man-Lyun Ha

Q-band micro-patch antennas implemented on a high resistivity silicon substrate using the surface micromachining technology

Using the surface micromachining technology composed of thick photoresist patterning and Cu-metal plating process, Q-band micro-patch antennas were implemented on high resistivity silicon (HRS) substrate. Because the application frequency is sufficiently high, the monolithically integrated, miniaturized micro antennas find applications in many systems. 42-GHz micro-patch antennas were fed by the coupling from the micro-strip feeder under the patch part. Using the parasitic capacitance in the posts contacted with HRS substrate, the patch sizes were decreased with slight decreasing of the bandwidth of antennas. Implemented patch antennas have 3 or 4 posts and their size was decreased with the increasing post capacitance in the radiating edges. Implemented patch sizes were 2.12, 1.78, and 1.41-mm with rectangular shape and the measured bandwidth under -10 dB of S11 was about 6 GHz(/spl sim/15%) with center frequency of 41.5 GHz in the case of 2.12 mm patch length.

A frequency agile floating-patch MEMS antenna for 42 GHz applications

A novel frequency agile floating-patch MEMS (micro-electro-mechanical system) antenna is proposed for 42 GHz applications. The floating-patch MEMS antenna is fabricated on a high resistivity silicon (HRS) substrate using surface micromachining technology. Simulation and experimental results for reflection coefficients and radiation patterns are presented.

Ku-band stop filter implemented on a high resistivity silicon with inverted microstrip line photonic bandgap (PBG) structure

We have developed the inverted microstrip line photonic bandgap (IML-PBG) structure using the surface micro-machining technology on the high resistivity silicon (HRS) substrate. Because, when the IML was fabricated, the holes for removing a sacrificial layer were necessary, we have introduced these holes into the PBG structure for the Ku-band stop filter (BSF). Rectangular spiral PBG structure showed the notch characteristics and the array with suitable distance showed the stop band with under -20 dB from 15 to 19 GHz and under -3 dB pass-band loss.

High-quality solenoid inductor using dielectric film for multichip modules

For multilayer applications, we made high-quality and easily fabricated solenoid inductors using a dielectric material (UPILEX-S, UBE Industries, Tokyo, Japan). These inductors fabricated on UPILEX-S had a larger Q factor compared to that of a spiral inductor fabricated on a silicon or GaAs substrate. Furthermore, it is possible to stack these inductors to make multichip modules using solder or gold stud bumps. From the measurement, solenoid inductors fabricated on 50-/spl mu/m-thick film showed very high Q factors and stable inductances.

MCM technology for RF tunable band pass filters implemented by integration of GaAs FETs and selectively oxidized porous silicon (SOPS)

RF tunable band pass filter has been implemented using the MCM-Si technology on selectively oxidized porous silicon (SOPS) substrate. The key approach of this paper is to integrate the GaAs FETs with silicon substrate to minimize the unwanted area by passive components on GaAs. All components except the active devices are fabricated on the SOPS substrate using the conventional thin film process and integrated through the wire bonding technique. This RF tunable filter has shown the center frequency from 5.64 GHz to 5.74 GHz with 0 dB insertion loss. The implemented tunable band pass filter has the Q-factor control scheme through gate bias resistor according with the frequency change. The whole area of GaAs die where all active devices have been fabricated is as small as 0.8/spl times/0.9 mm/sup 2/, which can be reduced to 0.6/spl times/0.7 mm/sup 2/.

An oxidized porous silicon (OPS) microlens implemented on thick OPS membrane for a silicon-based optoelectronic-multichip module (OE-MCM)

Using the silicon bulk micromachining and selectively oxidized porous silicon (SOPS) technology, a silicon dioxide microlens was implemented on thick oxidized porous silicon (OPS) membrane. Because the surface of microlens was the interface of OPS-Si, the surface roughness of lens was directly affected by the anodization current density, substrate resistivity, and high-frequency percent in ethanol-contained electrolyte. In the SOPS technology, the porous silicon layer (PSL) was formed under the mask layer with its horizontal-vertical ratio of about 0.8. During the formation of lens part, Si/sub 3/N/sub 4/ mask layer was also etched with constant etch rate and the PSL formed on the masked area was used as a membrane supporter. The initial open area and the thickness of the mask layer controlled the focal length of the OPS lens and its range was from 20 to 110 /spl mu/m. By using these microlenses, a new silicon-based optoelectronic-multichip module configuration was proposed.

Ka-band branch line coupler using high-performance air-buried microstrip lines

In this paper, a branch line coupler using airburied microstrip lines (ABMSLs) has been monolithically fabricated for millimeter-wave applications. Because the ABMSL structure employs air-dielectric medium and ground conductor walls surrounding strip signal line, it is very effective in reducing a dielectric loss, as well as parasitic coupling between close transmission lines over high frequency range. The fabricated branch line coupler shows a coupling and transmission loss of 3.6 dB and 3.9 dB, respectively at the center frequency of 29GHz. In the frequency range from 26GHz to 32GHz (20% bandwidth), it exhibits a return loss of better than 15 dB and isolation of better than 14 dB.

The fabrication of oxidized porous silicon membrane and its application to RF module

An oxidized porous silicon (OPS) membrane has been formed by anodization, thermal oxidation, and wet etching of a silicon wafer. Since the thick OPS layer is hetero silicon-dioxide, ethylene diamine pyrocatechol (EDP) does not etch it and so the self-etch-stop becomes possible. Passive RF elements, including coplanar waveguides, MIM capacitors, and spiral inductors, have been fabricated on this membrane and we have measured their performances. Using the design library of passive elements on OPS and OPS membranes, we have developed a low noise amplifier (LNA) for 2 GHz applications. The key idea of this LNA is based on the Friis equation and an input matching block was implemented on a locally formed nearly lossless OPS membrane to minimize the noise figure (NF). The inductively degenerated single-stage LNA showed 14 dB gain, 1.35 dB NF, and 5 dB IIP3 at 24 mW power dissipation.

New Through-Wafer Via Interconnections with Thick Oxidized Porous Silicon Sidewall Via

In this paper, we present the detailed fabrication process and high-frequency characterization of a new silicon through-wafer via interconnection and a low pass filter module flip-chip bonded to these via interconnections. An oxide liner of 18 µm thick for the via was fabricated on a complementary metal–oxide–semiconductor (CMOS)-grade low-resistivity 5 Ωcm silicon wafer using the oxidized porous silicon (OPS) process. The through-wafer vias were filled with copper by electroplating. For a via interconnection of 240 µm length and 70 µm diameter, the series inductance and resistance are 0.079 nH and 0.059 Ω each. A coplanar waveguide (CPW) and a RF low pass filter (LPF) module were assembled on this through-wafer via interconnection substrate.

Chip scale package for SAW filter on the oxidized porous silicon using flip-chip bonding and Cu plated metal wall

Chip scale package (CSP) for surface acoustic wave (SAW) filter has been implemented on silicon with thick oxidized porous silicon (OPS) layer using the thick plated metal wall and flip-chip bonding technique and the RF performance of SAW filter was measured. The key approach of this article was that the SAW filter and semiconductor RFICs were packaged on same substrate (OPS) with same packaging method (epoxy molding) at the same time. In packaging the SAW filter, the surface should be maintained in hermetic void for the performance reliability, and this has been solved by metal wall and epoxy molding compound. The silicon with thick OPS layer had good RF performance. The transmission line loss was below 0.1 dB/mm in L-band. flip-chip bonded SAW filter on OPS layer showed the -2.6 dB passband loss and 0.95 dB maximum ripple in 865-895 MHz range and the stopband attenuation was below -50 dB. For the demonstration of CSP SAW filter, we have developed the dual mode (CDMA and AMPS) receiver module where the SAW filter was interconnected between low noise amplifier (LNA) and down mixer which was also assembled on OPS layer using multichip module technology.