Electrical characteristics of metal-Al/sub 2/O/sub 3/-Si structure deposited by ICBE technique for application of semiconductor device fabrication

Abstract

We have deposited Al/sub 2/O/sub 3/ films by Ionized Cluster Beam Epitaxy (ICBE) technique at low substrate temperature (100/spl sim/500/spl deg/C). In this paper, the details of the film deposition system and fundamental characteristics of the Al-Al/sub 2/O/sub 3/-Si structure were described and the dielectric breakdown of Al/sub 2/O/sub 3/ was studied. Aluminum oxide (Al/sub 2/O/sub 3/) offers some unique advantages over the conventional silicon dioxide (SiO/sub 2/) gate insulator; greater resistance to ionic motion, better radiation hardness and higher possibility of obtaining low threshold voltage in MOSFETs and use as gate insulator in nonvolatile memory devices. We have undertaken a study of the dielectric breakdown of Al/sub 2/O/sub 3/ on Si deposited by ICBE technique. In our experiments, we have altered the Al/sub 2/O/sub 3/ thickness from 300 to 1400 /spl Aring/. The resistivity of Al/sub 2/O/sub 3/ films varies from 10/sup 8/ /spl Omega/-cm for films less than 100 /spl Aring/ to 10/sup 13/ /spl Omega/-cm for films on the order of 1000 /spl Aring/. The flat band shift is positive, indicating negative charging of oxide. The magnitude of the flat band shift is less for negative bias than for positive bias. The relative dielectric constant was 8.5/spl sim/10.5 and the electric breakdown fields were 6/spl sim/7 MV/cm (+bias) and 11/spl sim/12 MV/cm (-bias). The average fields required to produce breakdown in 10/sup 3/ sec were approximately 4.5 MV/cm for positive bias on either Al or Au field plates, 5.0 MV/cm for negative bias on Al and 6.5 MV/cm for negative bias on Au.