Characterization of delamination in laser micro transfer printing

Micro transfer printing is rapidly emerging as an effective method for heterogeneous materials integration. It transfers prefabricated micro- and nanoscale structures referred to as 'inks', from growth or fabrication donor substrates to functional receiver substrates. Laser Micro Transfer Printing (LMTP) is a laser-driven version of the micro transfer printing process, developed at the University of Illinois to enable non-contact release of the microstructure, thus making the transfer printing process independent of the properties or preparation of the receiving substrate. In this paper, an extensive study is conducted to investigate the capability of the LMTP process. Using square shaped silicon inks and polydimethylsiloxane (PDMS) stamps, and varying the lateral dimensions and thickness of the ink, the power absorption by the ink is measured to estimate the total energy stored in the ink-stamp system to initiate and propagate delamination at the interface. The delamination time for each size and thickness is experimentally observed at different laser beam powers using a high speed camera. Further, an axisymmetric thermomechanical FEM is developed to estimate the delamination temperatures at the interface utilizing the delamination time and power absorption for different ink sizes and thickness.