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Capacitor/Thin Film Stress Test Circuit

IP.com Disclosure Number: IPCOM000083930D
Original Publication Date: 1975-Aug-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Franco, JV: AUTHOR [+3]

Abstract

A circuit is described for stress testing a thin-film dielectric in an integrated circuit capacitor.

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Capacitor/Thin Film Stress Test Circuit

A circuit is described for stress testing a thin-film dielectric in an integrated circuit capacitor.

The figure shows the test voltage V(Test) which is DC or a slow ramp of less than 10v/sec ramp rate, which is applied at 1 to the capacitor dielectric 2 under test (CUT). Less than one microampere flows through a good CUT 2.

If breakdown occurs either by the self-heal phenomenon or by a short in catastrophic failure mode, the current increases substantially, turning the transistor Tx on and firing the silicon-controlled rectifier (SCR) 4. Resistor 12 is chosen for maximum sensitivity and to protect the device metallurgy from burnout. Transistor Tx can be any fast switching device. The choice of R1 is dependent on the supply voltage +V at 6 and the characteristics of transistor Tx. The SCR 4 also has to be a fast switching device. Resistor 7 is chosen to set the threshold or turn on of the SCR 4 and is adjusted to a minimum value, such that noise does not turn the SCR 4 on. The indicator lamp 8 may be either incandescent or a light-emitting diode (LED), depending on the voltage supply +V at 6.

Switches 9 and 10 are optional and can provide a lamp test by closing 9 or a circuit reset by opening 10. A recorder at output 11 can record the time and voltage of the test circuit. If the test circuit voltage is zero, the device is good. A voltage nearly equal to +V denotes a device failure. If the test circuit has responded to a self...