RF MEMS Switch with Wafer Level Package Utilizing Frit Glass Bonding

Abstract

This paper reports experimental results of RF characteristics up to 20 GHz of a RF MEMS switch applied with wafer level packaging. A glass wafer is used as a package substrate on which frit glass is printed as material to seal the MEMS devices. The package wafer is bonded to a device wafer, which consists of actuators and base substrates .The actuators are made of single crystal silicon that has less residual stress. The base substrate has through holes formed by sand blast. The switch achieves a low insertion loss of 1.3 dB and a high isolation of 19 dB up to 20 GHz, and can be mounted on to a circuit board with bumps, like flip chip. The wafer level packaging with low cost and high reliability will transfer RF MEMS devices, which has superior high frequency characteristics even in quasi-millimeter wave band, to the practical use.

Zero-level packaging for (RF-)MEMS implementing TSVs and metal bonding

“…This paper presents a 0-level package based on chip capping. Two features in particular make the package very attractive and distinct from previous implementations [7][8][9][10]:…”

“…The length of the feedthroughs varies with the width of the sealing ring and the design is such that the microstrip line keeps a characteristic impedance identical to the CPW (typically 50 ) [6]. (3) Vertical via's, implemented either in the MEMS substrate [7,8,9] or in the Cap [10] as shown in Fig. 1, present a more compact solution (smaller footprint) than the horizontal feedthrough designs, but, the process is more complex as through-wafer hole etching is required.…”

Hybrid RF-MEMS Switches Realized in SOI Wafers by Bulk Micromachining

“…When a switch is designed as an independent component, the package could be implemented in many forms: It could be a metallic or ceramic cover applied to each device diced die as in the TeraVicta design [31]; it could be a ceramic cover, usually a second wafer, performed as a wafer level packaging concept as in the Omron design [25]; or it could be part of a surface wafer processing as in the MEMtronics design [32]. While this concept helps minimize contamination, these package solutions have some design disadvantages: They must be RF connected to the circuit through ball grid array or wire bonding, which increases cross coupling and limits the high-frequency performance of the switch.…”

Mechanical characterizations of topology‐insensitive rivet bonding using the sidewall bond principle

“…Surface bond schemes such as anodic, fusion, and eutectic bonding cannot avoid leakage, even with roughness down to the submicron scale [3–5]. Interlayer bond schemes such as soldering, and the use of glass‐frit or adhesive bonding have certain advantages over the use of a non‐flat surface [6–8]. However, the interlayer can eventually spread due to the compressive force when an external force is applied to create the tight contact between the two wafers.…”