Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of individual circuit component or element
Reexamination Certificate
1999-05-10
2001-01-30
Metjahic, Safet (Department: 2858)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of individual circuit component or element
76, C257S048000
Reexamination Certificate
active
06181143
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to testing integrated circuits in general, and in particular to a method for performing reliability tests on integrated circuits. Still more particularly, the present invention relates to a method for performing a high-temperature burn-in test on integrated circuits.
2. Description of the Prior Art
A metal oxide semiconductor field effect transistor (MOSFET) or MOS transistor has two regions in a silicon substrate, namely, a source and a drain, which are disposed at a certain distance from each other. The MOS transistor also has an insulated gate disposed between the source and the drain. The gate is characterized by a threshold voltage (V
TH
) that determines the boundary between an ON state and an OFF state in the drain current.
It is well-known in the art that the threshold voltage of a MOS transistor changes as a function of temperature due to the availability of mobile electrons and other factors. Specifically, the threshold voltage decreases as temperature increases. This creates a problem for most integrated circuit (IC) designs because some qualification tests, such as a burn-in test, are required to be performed at high temperatures. Because the threshold voltages of the transistors are generally lower at high temperatures, the leakage currents and on-state drain currents of the transistors become significantly higher under burn-in conditions. In the prior art, this problem is solved by biasing the body of the transistors with additional contacts to the body of the transistors. This solution results in a much larger circuit and a reduction in the overall performance of the IC. Consequently, it is desirable to provide a method to maintain the threshold voltage of transistors within an integrated circuit during a high-temperature burn-in test without compromising the integrity of the test.
SUMMARY OF THE INVENTION
In accordance with a preferred embodiment of the present invention, a thin-film is placed on top of an integrated circuit having multiple transistors. An infra-red filter is then placed on top of the thin-film. All the transistors of the integrated circuit are radiated by an infra-red source through the thin-film and the infra-red filter when a high-temperature burn-in test is being performed.
All objects, features, and advantages of the present invention will become apparent in the following detailed written description.
REFERENCES:
patent: 5422498 (1995-06-01), Nikawa et al.
patent: 5767489 (1998-06-01), Ferrier
patent: 5892539 (1999-04-01), Colvin
patent: 5959462 (1999-09-01), Lum
patent: 5966019 (1999-10-01), Borden
patent: 5966022 (1999-10-01), Budnaitis et al.
patent: 6078183 (2000-06-01), Cole, Jr.
patent: 6091249 (2000-07-01), Talbot et al.
Felsman Bradley Vaden Gunter & Dillon, LLP
International Business Machines - Corporation
Metjahic Safet
Salys Casimer K.
Sundaram T. R.
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