Lateral nonuniformity of effective oxide charges in MOS capacitors with Al/sub 2/O/sub 3/ gate dielectrics |
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Authors: | Szu-Wei Huang Jenn-Gwo Hwu |
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Affiliation: | Nanya Technol. Corp., Taoyuan, Taiwan; |
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Abstract: | The high-frequency Terman's method for interface-trap-density (D/sub it/) extraction is used to examine the lateral nonuniformity (LNU) of effective oxide charges in MOS capacitors. The two-parallel-subcapacitor model is constructed to simulate LNU charges, and it was shown that the value of the found effective D/sub it/ appears negative as the LNU occurs in the gate oxide. This technique was first used to examine the effective oxide charge distribution in Al/sub 2/O/sub 3/ high-k gate dielectrics prepared by anodic oxidation and nitric-acid oxidation. It was found that the LNU effect in Al/sub 2/O/sub 3/ is sensitive to oxidation mechanisms and can be avoided by using an appropriate oxidation process. The proposed technique is useful for the preparation and reliability improvement of high-k gate dielectrics. |
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