Comparison between surface channel PMOS transistors processed with optical and X-ray lithography with regard to X-ray damage

In order to determine the influence of X-ray induced radiation damages, surface channel PMOS devices with partially scaled 0.5 mu m design rules were fabricated using optical and X-ray lithography. With a gate oxide thickness dox=10 nm the X-ray processed transistors show a threshold voltage shift Delta VT=-10 mV, whereas transistors with dox=20 nm show a VT shift of Delta VT=-40 mV relative to optically processed devices. The degradation under hot carrier injection in terms of deviations of Delta gm, Delta VT, Delta ID and Delta S is almost identical for both types of transistors and is of the order of 4%.