Effect of synchrotron radiation on electrical characteristics of SiO _xN_y thin films formed by rapid thermal processing in a N₂O ambient

The synchrotron radiation durability of SiO_xN_y films (about 10 nm) formed by rapid thermal processing in a N₂O ambient was studied. No significant difference between the flat-band voltage of SiO _xN_y-metal-oxide semiconductors (MOS) capacitors patterned by synchrotron radiation lithography (SR-MOS) and that of capacitors patterned by conventional optical lithography (OP-MOS) was observed. The midgap interface state density of the SR-MOS was approximately one order of magnitude larger than that of the OP-MOS. The differences between the SR-MOS and the OP-MOS were nearly independent of the SR dose in the range of 540-2700 mJ/cm², and were eliminated by annealing in a hydrogen ambient at 400°C for 30 min.