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Effects of Post-Metal Annealing on Electrical Characteristics and Thermal Stability of W[sub 2]N/Ta[sub 2]O[sub 5]/Si MOS Capacitors

2004; Institute of Physics; Volume: 151; Issue: 11 Linguagem: Inglês

10.1149/1.1800672

1945-7111

Pei-Chuen Jiang, Jen‐Sue Chen,

Advancements in Semiconductor Devices and Circuit Design

The thermal stability and electrical properties of metal oxide semiconductor (MOS) capacitors upon post-metal annealing in or ambient at 400-600°C for 30 min are investigated. After annealing at 400-500°C, the gate remains intact but, due to loss of nitrogen, partly transforms to after annealing at 600°C. The partial oxidation of is more noticeable when annealing in ambient than in and also induces greatly increased resistivity. However, the capacitance-voltage (C-V) curves of the MOS capacitors are similar before and after post-metal annealing. C-V hysteresis measurements showed that charges within the layer of the as-fabricated MOS structure are positive, and the density is cm−2. After annealing in the charge density decreased with increasing annealing temperature, and the charge polarity became negative after annealing at 600°C. In the charge polarity became negative right after annealing at 400°C, and the density was below cm−2. For the I-V curves, the leakage current decreases with increasing annealing temperature at positive bias, and annealing results in lower leakage currents than annealing. In contrast, the leakage currents are all similar when the samples are stressed at negative bias, regardless of the annealing temperature and ambient. © 2004 The Electrochemical Society. All rights reserved.