Effect of polysilicon gate on the flatband voltage shift and mobility degradation for ALD-Al/sub 2/O/sub 3/ gate dielectric
- 11 November 2002
- conference paper
- Published by Institute of Electrical and Electronics Engineers (IEEE)
- p. 645-648
- https://doi.org/10.1109/iedm.2000.904402
Abstract
Al/sub 2/O/sub 3/ (EOT=22.7 /spl Aring/) gate dielectric layer formed by Atomic Layer Deposition (ALD) process have been characterized for sub-100 nm CMOS devices. The gate leakage current was 3 orders of magnitude lower than that of SiO/sub 2/ and the hysteresis of C-V curve was not observed. However, the negative fixed charge induced the flat band voltage (Vfb) shift and degraded the channel mobility of MOS transistor. The Vfb shift was reduced and channel mobility was improved by applying P+ gate by BF/sub 2/ implantation. It is suggested that the phosphorous diffused from gate polysilicon has a role of network modifier in Al/sub 2/O/sub 3/ film and formation of the Al-O- dangling bond which may be ascribed to negative fixed charge.Keywords
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