ABSTRACT
We report a novel non-planar flexible silicon chip technology by means of patterning thin films of high residual stress on top of shaped thin silicon substrate. High residual stresses of thin films make thin chip deform into designed three-dimensional shapes. In this study, a series of patterned stress films and "petal-like" chips were fabricated and analyzed. Large curvatures can also be formed and maintained by the packaging process bonding the chips to constraining elements such as thin-film polymer ring structures. As a demonstration, a CMOS image-sensing retina chip is made into a contact-lens shape conforming to a human eyeball 12.5 m in radius. This non-planar and flexible chip technology provides a desirable device surface interface to soft or non-planar bio surfaces and opens up possibilities for many biomedical applications.
