In this paper we present a silicon wafer bonding technique for 3D microstructures using MEMS process technology. Photo-definable material with patternable characteristics served as the bonding layer between the silicon wafers. A bonding process was developed and several types of photo-definable material were tested for bonding strength and pattern spatial resolution. The results indicated that SU-8 is the best material with a bonding strength of up to 213 kg cm−2 (20.6 MPa), and a spatial resolution of 10 μm, at a layer thickness of up to 100 μm. The low-temperature bonding technique that is presented is particularly suitable for microstructure and microelectronics integration involved in MEMS packaging.

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Machining tools based on the excimer laser and x-ray lithography to make ultra-fine machining tool/molds are described in this paper. The lower high-aspect ratio resist molds are fabricated using the KrF excimer laser. The higher aspect-ratio resist molds are made using x-ray lithography. Both low and high aspect-ratio resist molds are then converted into metallic structures using electroforming. The NiCo/SiC microcomposite electroforming with low internal stress (∼0 kg mm −2 ) and high hardness (>Hv500) shows its feasibility as mold materials. An example of 2 mm thick integrated circuit (IC) packaging leadframe patterns using x-ray micromachining is illustrated to prove its feasible application. On the technical side, micro-structures with a high aspect ratio of 30 were developed using a graphite membrane based x-ray mask.