Method for wafer level packaging and fabricating cap structures

A method for wafer level packaging comprising steps of:

• providing a cap wafer;
• forming a plurality of cavities on a surface of the cap wafer;
• forming a patterned photoresist on the cap wafer and etching the cap wafer through the patterned photoresist to form a plurality of openings, then removing the patterned photoresist;
• bonding the cap wafer to a transparent wafer at the surface having the cavities, wherein the cavities are not bonded to the transparent wafer;
• segmenting the cap wafer around the cavities and removing a portion of the cap wafer not bonded to the transparent wafer to form a plurality of cap structures;
• providing a device wafer with a plurality of devices and a plurality of contact pads electrically connected to the devices;
• and
• hermetically bonding the cap structures to the device wafer at positions corresponding to the devices to form a plurality of hermetic windows.