Thermally stimulated current measurements of SiO sub 2 defect density and energy in irradiated metal-oxide-semiconductor capacitors
- Sandia National Laboratories, Department 1332, Albuquerque, New Mexico 87185-5800 (United States)
A modular system is described to measure thermally stimulated current (TSC) in irradiated metal-oxide-semiconductor (MOS) capacitors. Custom capacitor mounting allows accurate and convenient measurement of TSC with less than {similar to}0.1 pA error at temperatures up to {similar to}300 {degree}C. These measurements are used to estimate the densities and energy levels of defects in the SiO{sub 2} layer of irradiated MOS capacitors with 45, 98, and 350 nm oxides. For capacitors irradiated under positive bias, TSC measurements provide accurate estimates of radiation-induced trapped-positive-charge density only if performed under negative bias. It is shown that space-charge effects and capacitance changes during TSC measurement can lead to incorrect estimates of the radiation-induced trapped-charge density. We demonstrate that, for {ital n}-substrate capacitors, these effects can be minimized if the bias applied during TSC measurement is more negative than the inversion-point voltage on a post-irradiation capacitance-voltage ({ital C}-{ital V}) curve. This improves prior practice in the literature. Improved estimates are provided for trapped hole energies in SiO{sub 2}. Further, TSC measurements under proper bias conditions can be combined with conventional high-frequency {ital C}-{ital V} measurements to estimate hole- and electron-trap densities near the Si/SiO{sub 2} interface of irradiated MOS capacitors. To our knowledge, no other method can be used to quantitatively separate the effects of positive and negative oxide-trap charge on the radiation response of MOS devices. Finally, we show that irradiation with {similar to}10 keV x rays or {similar to}1.25 MeV Co-60 gamma rays leads to similar trapped-hole densities and energies in MOS capacitors with 350 nm nonradiation-hardened oxides.
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 7038185
- Journal Information:
- Review of Scientific Instruments; (United States), Journal Name: Review of Scientific Instruments; (United States) Vol. 63:12; ISSN RSINA; ISSN 0034-6748
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360605 -- Materials-- Radiation Effects
360606* -- Other Materials-- Physical Properties-- (1992-)
CAPACITORS
CHALCOGENIDES
ELECTRICAL EQUIPMENT
ELECTRICAL PROPERTIES
ELECTROMAGNETIC RADIATION
ENERGY-LEVEL DENSITY
EQUIPMENT
IONIZING RADIATIONS
NATIONAL ORGANIZATIONS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
PHYSICAL RADIATION EFFECTS
RADIATION EFFECTS
RADIATIONS
SANDIA LABORATORIES
SILICON COMPOUNDS
SILICON OXIDES
THERMOELECTRIC PROPERTIES
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US DOE
US ERDA
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