Charge densities at silicon interfaces prepared by wafer bonding

Abstract

It is found that Si/Si and Si/SiO/sub 2/ interfaces exhibit different interface charge properties when bonded at comparable temperatures and surface treatments. Thermally grown oxides were bonded to bare silicon surfaces and the bonded Si/SiO/sub 2/ interface was investigated on MOS-structures by the C-V technique. Interfaces prepared at temperatures in the range 900-1100 degrees c exhibited U-shaped interface state densities. Si/Si samples were prepared using a hydrophilizing surface treatment before wafer bonding. At the same annealing temperatures, the interface state densities of the bonded Si/Si interfaces were in the range 10/sup 11/-10/sup 13/ cm/sup -2/ eV/sup -1/. Si/Si interfaces are found to be very sensitive to prebond chemical treatment, while Si/SiO/sub 2/ interfaces are not. Native oxides at bonded silicon interfaces have a more pronounced influence on Si/Si interfaces than on Si/SiO/sub 2/ interfaces.<>