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Cross section schematic of MIM based capacitor structure. Porous OSG low-k films are deposited onto TaN/Ta in areas of 50 μm × 50 μm followed by PVD TaN/Ta barrier deposition and other conventional metallization steps. No low-k patterning is required.
Illustration of two different stress conditions. (a) Cu can drift into the low-k through the TaN/Ta barrier when a positive bias is applied on the top electrode. (b) Cu is not allowed to enter into the low-k when a negative potential/bias is applied on the top electrode. The arrows indicate the direction of the electric field.
Weibull plots of TDDB TTF for a positive bias (a) and negative bias (b). The Weibull shape parameter is 2.4 ± 0.4 for the positive bias and 2.2 ± 0.3 for the negative bias.
TDDB t63.2% vs. electric field for the MIM samples under both positive and negative bias conditions. The field acceleration factor for the E model is 3.0 ± 0.2 cm/MV for the positive bias and 3.1 ± 0.2 cm/MV for the negative bias.
TDDB t63.2% vs. electric field for MIS reference samples where Cu was directly deposited onto SiO2 and no barrier was used. The field acceleration factor for the E model is 1.2 ± 0.2 cm/MV for the positive bias and 9.1 ± 1.2 cm/MV for the negative bias. A significant degradation in TDDB performance was observed for the positive bias compared to the negative bias.
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