Monitoring of low-dose ion implantation in silicon |
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Authors: | Hara T Hagiwara H Ichikawa R Nakashima S Mizoguchi K Smith WL Welles C Hahn SK Larson L |
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Affiliation: | Dept. of Electr. Eng., Hosei Univ., Tokyo; |
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Abstract: | Monitoring of low-dose arsenic or boron ion implantation (doses: 5×1010 to 1×1013 cm-2) in silicon, which is required for threshold voltage control of MOS transistors, is studied. The thermal-wave (TW) signal intensity decreases monotonically with decreasing dose. The lowest detection limit for As+ and B+ implantations is 5×1010 and 1×1011 cm-2, respectively. Correlation of the TW signal intensity versus damage density, TW intensity versus dose, and laser Raman intensity versus dose is obtained. The TW intensity is also correlated with the sheet conductance, and the threshold voltage of the transistor. Therefore, this technique is useful as a nondestructive, highly sensitive dose monitor for low-dose implantation to achieve tight threshold voltage control in MOS transistors |
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