In this study we successfully bonded silicon wafer substrates with metal based thermocompression technology. This technology has the advantage of inherent possibility of hermetic sealing and electrical contact. We used three different kinds of metals: gold, copper and aluminum. We will show the hermeticity, bonding strength and reliability of the different processes and compare the results

In this paper, wafer-to-wafer AuSi eutectic bonding was investigated and evaluated with various sets of experimental parameters. Single crystalline Si and amorphous Si were bonded with different dimension Au layers and observed by optical measurements. Material composition, adhesion layer, electrical insulation, bonding parameters, and surface pre-treatments were discussed and have improved bonding performance. Bond strength determined by micro-chevron-test and shear test was evaluated as well as hermeticity. High bond yield was achieved with 4 inch and 6 inch wafer stacks

Abstract-This paper describes the concept and the development of key components of a novel multiple-beam antenna for satellite applications. The antenna is designed to be used in a transparent high-rate data relay system that links several low earth orbit (LEO) satellites to a single ground station via a satellite positioned on a geostationary orbit (GEO). The proposed antenna is based on the concept of an array-fed reflector. The antenna can track LEO satellites by switching between different subarrays of a bigger multifeed array using a reconfigurable switch matrix based on radio frequency micro-electromechanical system (RF MEMS) switches. The radiation characteristic of the antenna is further improved by combining digital beamforming with beam switching. In order to validate the proposed antenna concept and to show its suitability for space applications a demonstrator has been built. Measurements of the antenna's key components and of the demonstration system are given.

Successful commercialization of MEMS products extremely depends on cost factors. Especially the role of integration technologies like packaging at different levels, combining MEMS with integrated circuits, and to realize 3-dimensional packaged devices is more important than ever. Bonding technologies at wafer level are key factors for 3-d integration, realizing the mechanical bond and fulfilling certain requirements like strength, hermeticity, and reliability as well as the electrical interconnection of the different functional components. From a great variety of bonding techniques eutectic bonding has got a special importance today because both hermetically sealed packages and electrical interconnects could be performed within one bonding process. Furthermore, there are some advantages such as low processing temperature, low resulting stress, and high bonding strength. These properties are mainly investigated up today. Since the early 90-ies eutectic wafer bonding is known from very large scale integration (VLSI) and is used very often in industry. Even before that time eutectic bond processes were already used in the field of chip bonding.Within this paper the development and investigation of at least two eutectic bonding technologies will be described and characterized. Although the mechanical and micro structural properties of the bond will be shown, the realization and test of electrical interconnects is focused very clearly. With an integration of certain test structures the bonding strength, the electrical properties, and the hermeticity of eutectic bonds could be measured and evaluated. At least it will be concluded with an outlook for the feasibility of eutectic bonding in 3-d integrated smart micro systems.

The use of tantalum as adhesion layer for Au/Si eutectic bonding was investigated and compared to the frequently used materials chromium or titanium in the case of oxidized silicon substrates. Suitable test structures have been fabricated, bonded and evaluated. The eutectically bonded chips were characterized in respect to the maximum bearable tensile and shear loading. Interfacial reactions were observed by SEM and optical microscopy. As a significant result when tantalum was used, the external load until fracture occurred could be increased up to a factor of 3 in comparison to usually applied chromium or titanium. Analyses after bonding gave no prove for diffusion between the metallic alloy and the adhesion layer and delamination could be minimized therefore.