Wafer scale exfoliation of monocrystalline micro-scale silicon films




Ward, Martin John

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This document presents a new method and tool for controlling the thicknesses and quality of exfoliated monocrystalline silicon thin-films. The method described here is compatible with traditional wafer-based, metal-oxide-semiconductor (CMOS) fabrication techniques. It enables high-performance devices fabricated using CMOS processes to be easily integrated into flexible electronic products such as wearable or Internet of Things (IoT) devices. A finite-element linear-elastic fracture mechanics study was performed to understand the parameters that control the exfoliation process. A metamodel was created from the simulation results to inform the design and operation of a new exfoliation tool. This new exfoliation tool improves on previous iterations by creating a controlled peeling force that propagates the crack in a precise manner while utilizing the metamodel to produce higher quality films and actively compensate for errors in the tensile layer. Inline metrology was added to the tool to enable the error compensation. A careful precision design of the tool stage stage was performed to ensure the accuracy of the inline metrology. The results confirm the new tool's ability to correct the crack trajectory and show improvement in the uniformity and quality of the exfoliation compared to previous methods.


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