ASTM F996 2011 Edition, January 1, 2011
Standard Test Method for Separating an Ionizing Radiation-Induced MOSFET Threshold Voltage Shift Into Components Due to Oxide Trapped Holes and Interface States Using the Subthreshold Current–Voltage Characteristics
Published By:ASTM International (ASTM)
This test method covers the use of the subthreshold charge separation technique for analysis of ionizing radiation degradation of a gate dielectric in a metal-oxide-semiconducter-field-effect transistor (MOSFET) and an isolation dielectic in a parasitic MOSFET.2,3,4The subthreshold technique is used to separate the ionizing radiation-induced inversion voltage shift, ΔV INV into voltage shifts due to oxide trapped charge,Δ V ot and interface traps,Δ V it. This technique uses the pre- and post-irradiation drain to source current versus gate voltage characteristics in the MOSFET subthreshold region.
Procedures are given for measuring the MOSFET subthreshold current-voltage characteristics and for the calculation of results.
The application of this test method requires the MOSFET to have a substrate (body) contact.
Both pre- and post-irradiation MOSFET subthreshold source or drain curves must follow an exponential dependence on gate voltage for a minimum of two decades of current.
The values given in SI units are to be regarded as standard. No other units of measurement are included in this test method.
This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
2 McWhorter, P. J. and P. S. Winokur, "Simple Technique for Separating the Effects of Interface Traps and Trapped Oxide Charge in MOS Transistors," Applied Physics Letters, Vol 48, 1986, pp. 133–135.
3 DNA-TR-89-157, Subthreshold Technique for Fixed and Interface Trapped Charge Separation in Irradiated MOSFETs, available from National Technical Information Service, 5285 Port Royal Rd., Springfield, VA 22161.
4 Saks, N. S., and Anacona, M. G., "Generation of Interface States by Ionizing Radiation at 80K Measured by Charge Pumping and Subthreshold Slope Techniques," IEEE Transactions on Nuclear Science, Vol NS–34 , No. 6, 1987, pp. 1348–1354.