Degradation of the characteristics of p⁺ poly MOS capacitors with NO nitrided gate oxide due to post nitrogen annealing

Nitridation of oxide causes to accumulate nitrogen at SiO₂/Si interface and prevents the diffusion of boron to the Si substrate surface. This paper shows that in NO annealed oxide, N₂ post annealing causes degradation such as increasing leakage current and charge trapping. Also, it is found that for a constant current stress the time-to-breakdown in N₂ post annealed samples is one order of magnitude smaller than that of samples without N₂ post annealing. These increases of leakage current and charge trapping are found to be due to the penetration of boron into the oxide during subsequent high temperature post N₂ annealing.