Yong-Seung Bang

Switchable Composite Right/Left-Handed (S-CRLH) Transmission Line Using MEMS Switches

This letter presents a novel switchable composite right/left-handed (S-CRLH) metamaterial transmission line (TL) using MEMS switches. The proposed TL is based on a general CRLH TL with switchable capacitors and switchable shunt inductive stubs. The LH mode of the S-CRLH TL ranges from 7.5 GHz to 10.4 GHz. In these frequencies, the S-CRLH TL is able to switch from a negative phase response (phase lag) to a positive phase response (phase lead), or vice versa. This phase modulation can be obtained through a voltage, due to the use of MEMS switches. The size of the fabricated S-CRLH TL, including bias networks, is 4941 mum times 2076 mum and is compact thanks to the LH mode.

Fabrication and Characterization of RF MEMS Package Based on LTCC Lid Substrate and Gold-Tin Eutectic Bonding

This paper reports on an RF MEMS package based on LTCC technology and gold-tin eutectic bonding, and also evaluates physical and RF characteristics of the proposed structure. The package consists of an LTCC lid substrate and a bottom substrate, and assembled by gold-tin layer (80 wt. % gold 20 wt. % tin) for hermetic sealing and low temperature bonding. The helium leak rate of 17 packages were 1.38 X 10-8 atm-cc/sec, and the shear strength of the bonded surface showed in the range of 36 - 50 MPa. The RF characteristics were measured up to 10 GHz, and the packaging loss was calculated to be 0.1349 dB at 2 GHz.

Fabrication of a vertical sidewall using double-sided anisotropic etching of ?1?0?0? oriented silicon

A double-sided wet etch process has been proposed to fabricate vertical structures in ?1?0?0? oriented silicon substrate. Both sides of a {1?0?0} silicon wafer have been patterned identically along the ?1?1?0? direction, and etched using potassium hydroxide (KOH) solution. By precisly controlling the etch time, using etch-timer structure and additive control, structures with smooth and vertical {1?1?0} sidewalls have been fabricated at the edges of a rectangular opening without undercut. Rectangular through-holes, bridges and cantilevers have been constructed using the proposed process. The measured average surface roughness of the vertical sidewall was 481?nm, which has been further reduced to 217?nm and 218?nm by postetching using a KOH?IPA and TMAH?Triton mixture, respectively. Slanted {4?1?1} planes exposed at the concave corners during the vertical etch process have been successfully removed or diminished by the postetching process. A bridge structure with a high aspect ratio of 39:1 has been fabricated, and cantilevers without undercutting were successfully constructed by applying the compensation technique. The proposed process can potentially be utilized in place of the deep reactive ion etching process for the fabrication of structures having vertical through-holes, such as through-silicon vias, high aspect ratio springs and filters for microfluidic applications.

A substrate integrated waveguide probe applicable to broadband complex permittivity measurements

A planar-type open-ended coaxial probe with substrate integrated waveguide structure has been developed for broadband permittivity measurement. The proposed probe consists of a microstrip line, a shielded stripline, and a coaxial aperture. The shielded stripline was formed by placing via-hole arrays along the stripline to form a substrate integrated waveguide. To access the bandwidth of the proposed probe, back-to-back transmission lines with various via spacings are characterized. Based on this data, substrate integrated waveguide probes are designed and fabricated to measure the complex permittivity of 0.9 % saline up to 30 GHz. A 5 mm-wide substrate integrated waveguide probe with 2 mm via spacing shows distortion-free permittivity measurement up to 30 GHz, which is more than twice the bandwidth available from the conventional planar coaxial probe with the same probe width. The concept can be applied to silicon substrate, allowing a fully integrated active probe for broadband measurements.

Micromachined planar probe using half-SIW and half-shielded stripline structure for permittivity measurement

This paper reports on a micromachined planar type probe based on a novel hybrid shielded stripline. The proposed structure is for a broadband transverse electromagnetic (TEM) single-mode propagation using substrate integrated waveguide (SIW) and conventional shielded stripline. We suggested a novel probe structure that composed of half-SIW and half-shielded stripline, which combined through a benzocyclobutene (BCB) bonding layer. The structural concept and simple fabrication method has been introduced, and the S11 in air was measured from 0.5 GHz to 30 GHz. The permittivity measurement of 0.9 % saline has been performed to validate the proposed structure at frequencies from 0.5 GHz to 20 GHz.

Tunable composite right/left-handed transmission line with positive/negative phase tunability using integrated MEMS switches

This paper reports a novel compact tunable composite right/left-handed transmission line (CRLH-TL) with multi-state phase tunability using integrated MEMS switches. It is possible to select multiple states with different positive/negative phase responses. The phase states can be determined by controlling the admittance of capacitors and impedance of inductors through MEMS switch operations. At 9.5 GHz, each states phase is varied to be 26.7°, 14.6°, −6.7°, and −11.5°, where the first two states are in LH and the others in RH regions. At 9–15 GHz, insertion losses are measured to be less than 2.6 dB, and return losses were higher than 10 dB.

Fabrication of a Bottom Electrode for a Nano-scale Beam Resonator Using Backside Exposure with a Self-aligned Metal Mask

In this paper, we describe a self-aligned fabrication method for a nano-patterned bottom electrode using flood exposure from the backside. Misalignments between layers could cause the final devices to fail after the fabrication of the nano-scale bottom electrodes. A self-alignment was exploited to embed the bottom electrode inside the glass substrate. Aluminum patterns act as a dry etching mask to fabricate glass trenches as well as a self-aligned photomask during the flood exposure from the backside. The patterned photoresist (PR) has a negative sidewall slope using the flood exposure. The sidewall slopes of the glass trench and the patterned PR were 54.00° and 63.47°, respectively. The negative sidewall enables an embedment of a gold layer inside 0.7㎛ wide glass trenches. Gold residues on the trench edges were removed by the additional flood exposure with wet etching. The sidewall slopes of the patterned PR are related to the slopes of the glass trenches. Nano-scale bottom electrodes inside the glass trenches will be used in beam resonators operating at high resonant frequencies.

Fully integrated reconfigurable antenna steered by magnetic field

This paper presents a single antenna platform mechanically steered by magnetic force in which MMIC (Monolithic Microwave Integrated Circuit) and capacitors are fully integrated. The RF source, MMIC is vertically connected to the antenna plate, not on the BCB spring, so the antenna responses are not distorted with various tilting angles. A single MMIC is flip-chip bonded to increase productivity and reduce process time. The maximum deflection angles are 18.3 ° (H-plane) and 17.7 ° (E-plane) respectively and the tilting angles are proportional to the applied magnetic fields. RF beam patterns are obtained with various scanning angles. The scanning angle are − 14 °, 0 °, + 18 ° (H-plane), − 18 °, − 12 °, 0 °, + 12 °, + 16 ° (E-plane).