AN2386

Conclusions

27/30

4

Conclusions

This paper has studied the effect of the temperature on the MOSFET threshold voltage and

its thermal coefficient. In particular, a mathematical model for both parameters was

achieved and a comparison with real measurement was performed considering three low

voltage power MOSFET devices by ST; DEVICE1, DEVICE2 and DEVICE3. The simulated

and real data obtained for all the devices under test are quite close and, thus confirming the

validation of the theory.

The model has highlighted that, in order to decreases in absolute value TVTC to avoid

thermal run-away of the device, the thickness oxide, silicon and the gate doping

concentration must be decreased. However, minimizing TVTC and obtaining a standard

threshold voltage device can't be done by decreasing the three parameters together, they

must be rearranged as in the example shown in Figure 23. and Figure 24. of this article.

Another important result shown in this paper regards the example of the device DEVICE3.

In this case, the higher total charge concentration in the channel involves a band-gap

narrowing that increases in absolute value TVTC and makes the device more thermally

instable.