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The developed bonding process utilizes AuSn solder and provides liquid-proof sealing and multiple reliable electrical connections between the bonded wafers. The bond can withstand 300ºC and features a thin bond line (2-3 µm), high bond strength, excellent bond gap control, and low stress due to small amount of bonding material. A Nb/Au seed layer was shown to be an optimal adhesion and barrier film.

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The fabrication of multi-layer microfluidic biochips with integrated optical waveguides is described. The optical waveguides are metallized silicon v-grooves formed by anisotropic etching and capped by metal strips formed on pyrex glass. Microchannels are fabricated on the other side of the pyrex layer by isotropic wet etching and capped by a layer of PDMS. Optical coupling between the waveguides and microchannels is achieved by reflection from the end-facets of the waveguides. Numerical simulations and measurements of the waveguide properties are described and the excitation and detection of laser-induced fluorescence from 15 µm microspheres is demonstrated.

Electron-beam writing instruments for microcircuit fabrication are currently limited by total cycle time, field coverage, automatic registration, and reliability. A fully computer-controlled electron-beam pattern generator will be described which has been developed to advance the economic feasibility of electron beam writing. The instrument incorporates a fully automated mechanical stage and pattern registration system, computer designed deflection coils and a dynamic focusing system for correction of deflection introduced aberrations. Field coverage at the short working distance is variable, up to 0.120×0.120 in. with 60 000×60 000 addressable points in the field. Resolution over the field is 3500 lines at 8 mrad. Pattern distortion is within 1.0 μ over a 0.1 in. square field. The mechanical stage employs stepping motors driving lead screws to provide 3×3 in. movement in 250 μ in.steps. Additional travel of 7 in. is available in one axis for loading the wafer. The automatic pattern registration system employs four silicon etched “L” shaped fiducial marks located in the corners of each field. The electron beam is used to measure the position of the fiducial marks before each field exposure and position the pattern correctly on the wafer. Pattern position, size, rotation, and orthogonality are all typically set up by the automatic registration system in 300 msec. A vernier test pattern has been used to test the alignment system and shows registration better than ± 0.2 μ.