Low-temperature layer transfer techniques for integration of similar and dissimilar materials

This dissertation presents two groups of key layer transfer techniques that enable integration of similar and dissimilar semiconductor materials at low temperatures. The first group of the investigated techniques consists of direct wafer bonding and mechanical ion-cut for Si layer transfer while the second group includes polymer bonding, metal bonding, and laser lift-off for integration of III-V nitride films with Si substrates.; Successful Si layer transfer was achieved after oxygen plasma-assisted direct bonding of a donor-receptor wafer pair and Si layer separation by edge-initiated crack propagation along the layer of maximum lattice damage in the hydrogen implanted (dose of 8 x 1016/cm2 and H + energy of 28 keV) donor wafer. By the chosen mechanical ion-cut method, Si layer transfer from the Si donor wafer to a Si receptor wafer (Si-Si pair) and to a SiO2 receptor wafer (Si-SiO2 pair) was observed at maximum processing temperatures as low as 105°C for the Si-Si pair and 170°C for the Si-SiO2 pair, respectively. Experimental measurements of interface strengths verified the condition for successful layer transfer to be greater mechanical strength of the bonding interface than that of the separation interface.; One of the key processes for integration of III-V nitride films with dissimilar substrates is separation of film materials from its growth substrate by laser liftoff. A thermoelastic model was developed to describe separation criteria for the GaN/sapphire system based on thermal and mechanical phenomena during laser-film interactions. The model predicts a requirement of lower threshold laser fluence for highly strained GaN films. As predicted by the model, GaN films with smaller strain energy (<3 J/m2) required a higher laser fluence of 560 mJ/cm2 while those with higher residual strain energy (>3 J/m2) were separated at a lower fluence of 400 mJ/cm2.; InxGa1-xN/GaN light emitting diodes (LEDs) were also transferred onto Si substrates by polymer bonding, In-Pd metal bonding, laser liftoff, and selective polymer removal at processing temperatures below 200°C. Electrical characterization of the transferred devices revealed improvements of serial resistance by 22% and power consumption by 10% at a drive current of 20mA. Optical output of the transferred LEDs measured in the peak emission intensity was also improved by 25%.