A1203 (EOT=22.7A) gate dielectric layer formed by Atomic Layer Deposition (ALD) process have been characterized for sub-100m CMOS devices. The gate leakage current was 3 orders of magnitude lower than that of Si02 and the histeresis of C-V curve was not obselved. 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 BF2 implantation. It is suggested that the phosphorous diffused from gate polysilicon has a role of network modifier in A1203 film and formation of the A1-0-dangling bond which may be ascribed to negative fixed charge.

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