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Defects Detection in a Metal Oxide Silicon Structure

IP.com Disclosure Number: IPCOM000077138D
Original Publication Date: 1972-Jun-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Stelmak, J: AUTHOR

Abstract

This is a method of detecting defects in field-effect transistor (FET) gate oxides which is nondestructive. The method involves measuring the low-current current-voltage characteristics of the gate oxide. Oxides with defects give an anomalous I-V characteristic. These anomalous characteristics are distinguished by a current level significantly higher than the current for an ideal SiO(2) dielectric for any given voltage.

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Defects Detection in a Metal Oxide Silicon Structure

This is a method of detecting defects in field-effect transistor (FET) gate oxides which is nondestructive. The method involves measuring the low-current current-voltage characteristics of the gate oxide. Oxides with defects give an anomalous I-V characteristic. These anomalous characteristics are distinguished by a current level significantly higher than the current for an ideal SiO(2) dielectric for any given voltage.

The method of detection involves applying a bias voltage across the metal- oxide-silicon (MOS) structure, as shown in Fig. 1, at an appropriate level so that the current of an ideal oxide layer is negligible relative to the detection limits of the current measurement, but the anomalous characteristics are several orders of magnitude higher in current value.

For example, with several hundred angstrom oxides, thirty-five volts applied across the oxide will produce approximately 10-14 amps or less on an ideal oxide, but the anomalous currents are 10-13 up to 10-10 and even higher. Selecting those devices which show leakage currents below 10-13 is an effective screen for removing oxides with defects. An additional advantage is that the oxide layers with defects can now be analyzed before they are actually broken down, to see what the cause of the defects may be.

The normal characteristic electron tunneling currents are first determined for the MOS structure as per curves A and B in Fig. 2. These rel...