Low-stress wafer-level transfer bonding of polymer layers using floatation

We introduce and demonstrate a method for low-stress demolding and transfer of polymer microstructures from their mold to a destination wafer. This method has the advantage of not involving stress-inducing handling steps present in traditional demolding and transfer bonding procedures. The mold is coated with a sacrificial layer which is dissolved in an ultrasonication water bath, leading to that the polymer sheet floats to the water surface. This generic method facilitates transfer of large area, thin layers and is here demonstrated for demolding and transfer bonding of wafer-sized layers of microstructured PDMS.