High Field Phenomena in Thermal SiO[sub 2]
Journal of the Electrochemical Society
High field phenomena in thermally grown Si0 2 have been investigated by a combination of three techniques: (i) current-voltage characterization, (ii) CV measurements, and (iii) forced-current voltage-time characteristics. Comparison with theoretical Fowler-Nordheim predictions was used in the current-voltage technique. Four oxide thicknesses were studied: 160,345, 652, and 1452-\. All structures were nonrecessed AlJSiOiSi capacitors of various areas. The substrate was n-type silicon. Interface
... silicon. Interface trap formation and charging with electrons near the cathode during injection from Si was observed for all oxides. Creation of immobile holes in the oxide valence band by impact ionization was observed for the thicker oxides, but not the thinnest. Bulk trapping was significant when electrons were injected from Al into the thicker oxides. The AlJSi0 2 interface was considerably leakier in thicker oxides than predicted by the Fowler-Nordheim theory. It is important to consider these high field phenomena in reliability questions because they constitute a true wear-out mechanism for intrinsic (i.e., with no defects) thermal oxides. As oxides become thinner in devices, high field phenomena become a more practical concern.