Reevaluating the worst-case radiation response of MOS transistors

Conference · Thu Jan 01 04:00:00 EST 1987

OSTI ID:5982009

Fleetwood, D M

Predicting worst-case response of a semiconductor device to ionizing radiation is a formidable challenge. As processes change and MOS gate insulators become thinner in advanced VLSI and VHSIC technologies, failure mechanisms must be constantly re-examined. This series of Vugraphs presents results of a recent study in which more than 100 MOS transistors were monitored for up to 300 days after Co-60 exposure. Based on these results, a reevaluation of ''worst-case'' n-channel transistor response (most positive threshold voltage shift) in low-dose-rate and postirradiation environments is required in many cases. In this presentation it is shown for Sandia hardened n-channel transistors with a 32 nm gate oxide, that switching from zero-volt bias, held during the entire radiation period, to positive bias during anneal clearly leads to a more positive threshold voltage shift (and thus the slowest circuit response) after Co-60 exposure than the standard case of maintaining positive bias during irradiation and anneal. We conclude that irradiating these kinds of transistors with zero-volt bias, and annealing with positive bias, leads to worst-case postirradiation response. For commercial devices (with few interface states at doses of interest), on the other hand, device response only improves postirradiation, and worst-case response (in terms of device leakage) is for devices irradiated under positive bias and annealed with zero-volts bias. 2 refs., 9 figs.

• Research Organization: Sandia National Labs., Albuquerque, NM (USA)
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 5982009
• Report Number(s): SAND-87-1001C; CONF-8708137-1-Vugraphs; ON: DE87014157
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360605 -- Materials-- Radiation Effects
42 ENGINEERING
420800* -- Engineering-- Electronic Circuits & Devices-- (-1989)
ANNEALING
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
COBALT 60
COBALT ISOTOPES
DATA
EVALUATION
EXPERIMENTAL DATA
HEAT TREATMENTS
INFORMATION
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
IRRADIATION
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
MINUTES LIVING RADIOISOTOPES
MOS TRANSISTORS
NUCLEI
NUMERICAL DATA
ODD-ODD NUCLEI
PHYSICAL RADIATION EFFECTS
RADIATION EFFECTS
RADIOISOTOPES
SEMICONDUCTOR DEVICES
TRANSISTORS
YEARS LIVING RADIOISOTOPES