The effect of hydrogen on trap generation, positive charge trapping, and time-dependent dielectric breakdown of gate oxides

The effect of high-temperature ( approximately=900 degrees C) hydrogen on the gate oxides of MOS devices is studied. Hydrogen is introduced into devices by either high-temperature anneal or conventional process steps such as low-pressure chemical vapor deposition (LPCVD) of Si/sub 3/N/sub 4/. In all cases, measurements of high-field stress behavior show that high-temperature hydrogen steps reduce time to breakdown and increase bulk and interface trap generation, but do not affect the generation of positive charge. These results indicate that the wear-out mechanism of gate oxides at high fields is related to trap generation rather than to accumulation of positive charge.<
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