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Researchers Resurrect, Improve Technique for Detecting Transistor Defects

improvement on traditional charge pumping technique

The difference between the current output generated by f1 and f2 voltages indicates the number of defects.

Credit: NIST

Researchers at the National Institute of Standards and Technology have revived and improved a once-reliable technique to identify and count defects in transistors. The new, modified charge pumping technique can detect single defects in devices with 1.7-nanometer gate dielectrics and can indicate where the defects are located in a transistor.

Charge pumping is a two-step process in which the examiner alternately pulses the gate with a positive test voltage, then a negative one. The insulating oxide layer in modern transistors is now so thin that an effect from the realm of quantum mechanics comes into play, confounding measurements using the traditional charge-pumping method.

NIST researchers James Ashton, Mark Anders, and Jason Ryan have found a way to salvage the technique so that it not only works for ultrathin transistor components but is also more sensitive, enabling scientists to record signals from a single defect.

They describe their frequency-modulated charge pumping technique in research published in Applied Physics Letters.

"We've given charge pumping a new lease on life," Ashton says.

From National Institute of Standards and Technology
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