The Effects of Ionizing Radiation on the Breakdown Voltage
of P-Channel Power-MOSFETs
Abstract
The effects of ionizing radiation on the breakdown voltage of p-channel power
MOSFETs were examined through two-dimensional simulation. Breakdown-voltage
performance of p-channel power MOSFETs was found to be very different from
corresponding n-channel power MOSFETs. In p-channel devices, simulation showed
breakdown-voltage enhancement for low values of positive oxide-trapped charge,
Not, whereas for high values of Not, the breakdown voltage may
or may not continue to increase, and may actually decrease in some topologies.
For comparison, in n-channel devices, increases in Not always cause
breakdown-voltage degradation. The uncertainties stem from the interaction
of the depletion region of the device (which is a function of its termination
method) with its isolation technology, making it difficult to predict breakdown
voltage for large Not. However, insights gained through analysis of
depletion-region spreading in p-channel devices suggest a termination/isolation
scheme, the VLD-FRR, that will enhance p-channel device reliability in radiation
environments.
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Last modified: June 14, 2005 -- © François Cellier