Thermally stimulated current measurements of SiO sub 2 defect density and energy in irradiated metal-oxide-semiconductor capacitors

Journal Article · Tue Dec 01 00:00:00 EST 1992 · Review of Scientific Instruments; (United States)

DOI:https://doi.org/10.1063/1.1143354· OSTI ID:7038185

Reber, Jr, R A; Fleetwood, D M ^[1]

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1. 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), Vol. 63:12; ISSN 0034-6748
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CAPACITORS
PHYSICAL RADIATION EFFECTS
THERMOELECTRIC PROPERTIES
SILICON OXIDES
ENERGY-LEVEL DENSITY
SANDIA LABORATORIES
X RADIATION
CHALCOGENIDES
ELECTRICAL EQUIPMENT
ELECTRICAL PROPERTIES
ELECTROMAGNETIC RADIATION
EQUIPMENT
IONIZING RADIATIONS
NATIONAL ORGANIZATIONS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
RADIATION EFFECTS
RADIATIONS
SILICON COMPOUNDS
US AEC
US DOE
US ERDA
US ORGANIZATIONS
360606* - Other Materials- Physical Properties- (1992-)
360605 - Materials- Radiation Effects