Flexible substrate and release layer for flexible MEMS devices

In this letter, the authors report a process for flexible substrate fabrication on silicon carrier wafers and the subsequent release of the flexible substrate from the carrier wafer. Polyimides with relatively high glass transition temperatures (> 400 degrees C) are employed for the flexible substrate. The fabrication steps utilize the low adhesion strength, high glass transition temperature (360 degrees C) HD Microsystems PI2611 as the release layer. The PI2611 release layer is protected from exposure to common solvents and "remover" used during lift-off or wafer cleaning processes by creating a seal with the HD Microsystems PI5878G substrate around the perimeter of the wafer. This flexible MEMS fabrication technique allows conventional fabrication equipment to be used. (C) 2013 American Vacuum Society.