Fusion bonding of Si wafers investigated by x ray diffraction

The interface structure of bonded Si(001) wafers with twist angle 6.5 degrees is studied as a function of annealing temperature. An ordered structure is observed in x-ray diffraction by monitoring a satellite reflection due to the periodic modulation near the interface, which results from the formation of a regular array of screw dislocations.

This satellite reflection first appears at an annealing temperature of 800 degrees C, and increases abruptly up to temperatures of 1000 degrees C. We propose that this transition occurs when there is sufficient mobility for the reorganization of atomic steps and terraces in the interface region. (C) 2000 American Institute of Physics.