Ik-Jae Hyeon

Circular/Linear Polarization Reconfigurable Antenna on Simplified RF-MEMS Packaging Platform in K-Band

A linear-polarization (LP)/circular-polarization (CP) switchable reconfigurable antenna using a radio frequency micro-electro-mechanical-system (RF-MEMS) switch is proposed and a novel package platform is introduced. Since the package substrate of the novel package platform is used as a radiation aperture substrate of the antenna structure, the fabrication process can be simplified, and degradation of radiation performance can be prevented. As the radiation aperture exists on the top side of the package substrate, an aperture-coupling feed structure is employed. To implement the LP-CP-switchable antenna based on the package platform, a stub, acting as the other feed, is added to a slot ring and is connected to the RF-MEMS switch with an on/off state. The proposed antenna is simulated using the Finite-Element Method, after which it is fabricated and measured. The measured 10 dB impedance bandwidths (BWs) are 22.90% (LP state) and 28.43% (CP state). The measured 3 dB axial ratio BW is 13.07% in the CP state. The measured gains at 21 GHz are 2.63 dBi (LP state) and 3.90 dBi (CP state).

Silicon/quartz bonding and quartz deep RIE for the fabrication of quartz resonator structures

In this paper, silicon/quartz bonding and quartz deep RIE (DRIE) processes have been developed to fabricate micromechanical quartz resonator structures. A low temperature (< 300degC), plasma-assisted silicon/quartz bonding condition that can provide the maximum bonding shear strength of 10 MPa has been experimentally constructed. The bonded silicon wafer was first applied to an etch mask of quartz, and thick quartz microstructures (~ 50 mum) have been fabricated by deep RIE of quartz with a gas mixture of C4F8 and He. In addition, a simple fused-quartz freestanding cantilever structure has been successfully fabricated by using the bonded silicon wafer not only for an etch mask layer but also for a substrate for quartz structures. The developed bonding and deep RIE processes, in combination with a proper metallization technique, are expected to be used for the wafer-level fabrication of freestanding quartz resonators.

Fabrication of Electrostatically-Actuated, In-Plane Fused Quartz Resonators using Silicon-on-Quartz (SOQ) Bonding and Quartz Drie

This paper reports a novel process to fabricate electrostatically-actuated, in-plane micromechanical resonators made of fused quartz for high-Q microsensor applications. Two key processes - low temperature plasma-assisted Silicon-on-Quartz (SoQ) direct bonding and quartz DRIE using C4F8/He plasma - have been used in combination with thin metallization to fabricate fused quartz resonators driven by electrostatic force. The proposed method enables wafer-level fabrication of fused quartz resonators readily mounted on the substrate, which is advantageous over the conventional fabrication method of quartz crystal resonators. By using the proposed process, 40-¿m-thick laterally-driven fused quartz cantilever resonators have been successfully fabricated. The measured Q-values of the metal-coated fused quartz cantilevers are 21,700~48,900 according to the length of the cantilever.

Millimeter-Wave Substrate Integrated Waveguide Using Micromachined Tungsten-Coated Through Glass Silicon Via Structures

A millimeter-wave substrate integrated waveguide (SIW) has been demonstrated using micromachined tungsten-coated through glass silicon via (TGSV) structures. Two-step deep reactive ion etching (DRIE) of silicon vias and selective tungsten coating onto them using a shadow mask are combined with glass reflow techniques to realize a glass substrate with metal-coated TGSVs for millimeter-wave applications. The proposed metal-coated TGSV structures effectively replace the metallic vias in conventional through glass via (TGV) substrates, in which an additional individual glass machining process to form micro holes in the glass substrate as well as a time-consuming metal-filling process are required. This metal-coated TGSV substrate is applied to fabricate a SIW operating at Ka-band as a test vehicle. The fabricated SIW shows an average insertion loss of 0.69 ± 0.18 dB and a return loss better than 10 dB in a frequency range from 20 GHz to 45 GHz.

Millimeter-wave filter using novel micromachined substrate integrated waveguide structure with embedded silicon vias in BCB dilectrics

This paper reports a millimeter-wave bandpass filter (BPF) based on a novel micromachined substrate integrated waveguide (SIW) structure with square complementary split-ring resonators (CSRRs). Four CSRRs are introduced to the SIW as an element providing passband characteristics below a cutoff frequency of the waveguide required for BPF. Unlike usual SIW-BPFs, the proposed BPF can be integrated with silicon-based circuits or RF MEMS devices by micromachining batch process due to its silicon process compatibility. In order to change the propagation mode from TEM to TE10, triangular slots are utilized as a CPW to waveguide transition. The fabricated BPF shows a high selectivity with a minimum insertion loss of 2.27 dB at 14 GHz and a 3-dB bandwidth of 9.3 %. These measured results are in good agreement with the simulation results.

Polarization switching antenna integrated with RF MEMS switches using silicon-on-quartz and BCB packaging platform

This paper reports a polarization switching antenna integrated with RF MEMS switches based on the novel packaging platform using silicon-on-quartz (SoQ) substrate and BCB(benzocyclobutene) bonding technique. By using the SoQ wafer as an antenna substrate as well as for a packaging lid, fabrication complexity and degradation of RF performances of the antenna due to the parasitic effects coming from the packaging method can be reduced. A fully-packaged K-band antenna capable of switching between two linear polarization states by actuating integrated silicon MEMS switches has been successfully fabricated. Performances of the antenna have been simulated and experimentally evaluated.