Stress Time Component

7.4.1 Stress Time Component

First, the position of the curvature is characterized by $τA$ for PBTI and $τB$ for NBTI after Fig. 7.4. $τA$ and $τB$ obviously depend on the stress conditions, which is displayed in Fig. 7.6 in more detail. The longer the device is stressed for equal $Eox$ , the later the kink occurs. Interestingly the kink-time normalized to the stress time $tstr$ is roughly a constant, indicating a connection between $t str$ and the recovery behavior (cf. the universal recovery in Chapter 4.1). This is also schematically shown in Fig. 7.4, where increasing $tstr$ shifts the relaxation curve towards larger $trel$ .

Figure 7.6: As already shown by the dotted lines in Fig. 7.5, a longer stress increases the kink time $τA$ for PBTI or $τB$ for NBTI. Scaling $τA$ or $τB$ to $tstr$ reveals a proportionality of the kink time and $tstr$ . The extraction does not work properly with two kinks at $τA$ and $τB$ or without a kink, due to the glancing intersection of the fits, resulting in an ambiguous kink point. The positions for these special cases at $t = 100s str$ are indicated by dotted lines.

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