Atomic diffusion bonding with oxide underlayers using Al and amorphous Si films for high optical density applications

Atomic diffusion bonding with oxide underlayers using Al and a-Si films was examined to create a bonded interface with Al2O3 and Si-oxides having large band gaps for high optical density applications. Surface free energy of the bonded interface greater than 2 J m(-2) and 100% light transmittance were achieved after annealing at 300 degrees C in the range of film thicknesses delta on both sides from 0.3 to 0.5 nm using Al films and with delta of around 0.5 nm using a-Si films. Structural analyses revealed that the bonded interface consists of Al2O3 and Si-oxides with oxygen dissociated from oxide underlayers.