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 °C) are employed for the flexible substrate. The fabrication steps utilize the low adhesion strength, high glass transition temperature (360 °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.