An observation of breakdown characteristics on thick silicon oxide

Abstract

We have investigated the current-voltage characteristics of silicon dioxide (SiO/sub 2/) with its destruction phenomena and the electric damage which would be introduced by a measurement of leakage current. The samples are oxidized at 820/spl deg/C/spl sim/1215/spl deg/C and their thickness is 10 nm/spl sim/1650 nm. We have confirmed that the SiO/sub 2/ film under the electric stress begins to be damaged at a specific electric field strength. This specific value, /spl ap/8 MV/cm for the 75/spl sim/100 nm SiO/sub 2/, is distinctly lower than the dielectric breakdown value and decreases with increasing SiO/sub 2/ thickness. We have found for the first time that the leakage current could suddenly increase up to 100/spl sim/10000 times near the specific electric field strength if the SiO/sub 2/ film was treated above a certain temperature and possesses some thickness. And we suspect that this steep increment of leakage current of SiO/sub 2/ is due to the multiplication phenomenon which is activated by the electron's impact ionization. We have also noticed that the whole current-voltage characteristic of SiO/sub 2/ films is very similar to that of high voltage silicon pn-diodes in the whole range from the very low leakage current to the destruction phenomenon.