A NEW PORTRAYAL OF OXIDATION OF UNDOPED POLYCRYSTALLINE SILICON FILMSIN A SHORT-DURATION

Both polysilicon films low-pressure chemical-vapor-deposited (LPCVD) a t 625 degrees C and amorphous films deposited at 550 degrees C with su bsequent annealing at 600 degrees C for 24 h to form polysilicon films were used to grow polyoxides at 850 degrees C in wet or dry oxygen. D etailed high-resolution transmission electron microscopy (HRTEM) and X -ray diffraction (XRD) studies have been performed to determine the mi crostructures of the polyoxide/polysilicon interface and the crystalli nity of the polysilicon films. It is found that the oxidation phenomen a of these two films are very different. For the recrystallized amorph ous silicon specimens, the polyoxide/polysilicon interface is very fla t because of the poor crystallinity and low-angle grain boundaries bet ween the grains. On the other hand, the polyoxide/polysilicon interfac e is rough for the as-deposited polysilicon samples due to the distinc t grain characteristics and the high-angle grain boundaries between th ese grains.