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

Ik-Jae Hyeon,Chang-Wook Baek

doi:10.3390/mi9040172

Abstract

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.

Highlights

With the increased input/output (I/O) numbers of the integrated circuits (ICs), interposers with through substrate vias are essential for the small footprint, high density and low power 3-D stacking integration in advanced electronic systems
Glass interposers based on the through glass via (TGV) technology have been extensively studied as an alternative for the silicon interposers [3,4,5,6,7,8,9,10,11,12,13,14]
We previously demonstrated micromachined versions of substrate integrated waveguide (SIW) to improve integration capability of the SIW with semiconductor or microelectromechanical systems (MEMS) devices for tunable SIW-based circuits at millimeter-wave frequencies

Summary

Introduction

With the increased input/output (I/O) numbers of the integrated circuits (ICs), interposers with through substrate vias are essential for the small footprint, high density and low power 3-D stacking integration in advanced electronic systems. Silicon interposers using through silicon vias (TSV) have been reported numerously for the last couple of years as an alternative for conventional organic substrates because of their advantages such as ultrahigh wiring capacity, shorter signal paths with smaller parasitic effects, ease of wafer processing and die matched coefficient of thermal expansion (CTE) to the ICs [1,2]. The TSV technologies, have their own challenges including high fabrication cost, process complexity and large electrical substrate losses. As a substrate material, has several merits; closely matched CTE to silicon dies, high dimensional stability and availability in thin and large panels. The high signal isolation, low substrate loss and low material and manufacturing cost of the glass compared to conventional silicon wafers make the glass interposers attractive platforms for high frequency radio frequency (RF)/microwave passive components and packaging. Different types of RF components based on the glass interposers with TGVs such as filters [4], 3D inductors [8,9] and antennas [13,14] have been reported

Methods

Results

Conclusion