INVESTIGATION ON THE INTERFACE OF THE POLYCRYSTALLINE SILICON CONTACTED DIODE FORMED WITH A STACKED AMORPHOUS-SILICON FILM

Abstract

The structural morphology of the poly-single crystalline silicon interface of a diode formed with a stacked-amorphous-silicon (SAS) film has been investigated. Secondary ion mass spectroscopy analyses showed the existence of multi-dopant segregation peaks at each layer boundary and at the poly-single crystalline silicon interface. The break-up at the poly-single silicon interface and the epitaxial regrowth of the polysilicon realigned to the silicon substrate were found to depend not only on the polysilicon deposition and the post annealing conditions, but also on the number and the thickness of the stacked amorphous silicon layers. For the diode formed with a six-layer stacked amorphous silicon, break-up of the interface was found to occur even at an annealing temperature as low as 900-degrees-C. After an additional annealing at 1000-degrees-C for 20 min, the interface was fully broken-up and the epitaxial regrowth layer of the polysilicon could be as thick as 760 angstrom.