Yield management by threshold voltage adjustment in back-end process

Shinya Ito; Ko Noguchi; Tadahiko Horiuchi

doi:10.1117/12.323965

4 September 1998 Yield management by threshold voltage adjustment in back-end process

Shinya Ito, Ko Noguchi, Tadahiko Horiuchi

Proceedings Volume 3506, Microelectronic Device Technology II; (1998) https://doi.org/10.1117/12.323965
Event: Microelectronic Manufacturing, 1998, Santa Clara, CA, United States

Abstract

For high-end or low-power CMOS devices, accurate control of the threshold voltage (V_th) is crucial because V_th deviation from the target value decreases the performance and yield of devices. In the conventional process, V_th is determined by channel doping performed early in the fabrication process, and cannot be corrected afterwards even if the variation in the gate length and gate oxide thickness resulting from the fabrication process is large. With the scaling down of devices, accurate control of V_th becomes even more difficult because the effect of the process variation becomes more pronounced. We propose a new feed- forward adjustment scheme for V_th by using post- metallization hydrogen ion implantation. The implanted hydrogen deactivates channel impurities and decreases V_th for both NMOS and PMOSFETs, and this effect remains stable after standard back-end process including post-metallization annealing (400 degrees Celsius). Th V_th change obtained was about 0.1 V at a hydrogen dosage of 1 x 10¹³ cm^-2 for NMOS and PMOS FETs. The impact of this technique on oxide reliability is small and acceptable for practical usage. Using this technique, we can adjust V_th after we measure its actual value and compensate for the V_th variation caused by processing. Hydrogen ion implantation is thus a useful technique for feed-forward yield management.

Citation Download Citation

Shinya Ito, Ko Noguchi, and Tadahiko Horiuchi "Yield management by threshold voltage adjustment in back-end process", Proc. SPIE 3506, Microelectronic Device Technology II, (4 September 1998); https://doi.org/10.1117/12.323965

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