Geometrical Deviation and Residual Strain in Novel Silicon-on-Aluminum-Nitride Bonded Wafers

Aluminum nitride (AlN), with much higher thermal conductivity, is considered to be an excellent alternative to the SiO₂ layer in traditional silicon-on-insulator (SOI) materials. The silicon-on-aluminum-nitride (SOAN) structure was fabricated by the smart-cut process to alleviate the self-heating effects for traditional SOI. The convergent beam Kikuchi line diffraction pattern results show that some rotational misalignment exists when two wafers are bonded, which is about 3°. The high-resolution x-ray diffraction result indicates that, before annealed at high temperature, the residual lattice strain in the top silicon layer is tensile. After annealed at 1100°C for an hour, the strain in the top Si decreases greatly and reverses from tensile to the slightly compressive as a result of viscous flow of AlN.