Integration of electrodes in Si channels using low temperature polymethylmethacrylate bonding

Low temperature Si to glass bonding using polymethylmethacrylate (PMMA) as an adhesive layer is developed to integrate electrodes with Si channels. The integrated microsystem contains channels dry etched in Si with widths ranging from 3 to 100 μm and depths ranging from 100 nm to 30 μm The channels are bonded to a 100 μm thick glass consisting of 600 nm thick patterned PMMA and 20/50 nm thick Cr/Au electrodes, with PMMA as an adhesive layer. The typical bond strength is 3 MPa, obtained by bonding at 110°C with 600 nm thick PMMA. Fluidic flow studies are carried out in channels that are 50 and 100 μm wide with a depth of 100 nm. De-ionized water flows through the sealed Si channels due to capillary pressure with an initial velocity of 0.65 mm/s for 50 μm wide and 100 nm deep channels. Electric fields are used to induce DNA motion with velocities from 2.4 to 14.5 μm/s in 100 μm wide and 20 μm deep channels. The forces generated by the fields and the fluid flow are also used to stretch the tethered DNA molecules up to 15 μm long in the microchannels. © 2007 American Vacuum Society.