THz emission characteristics from LSI-TEG chips under zero bias voltage

THz emission characteristics from a large scale integration circuit test element group (LSI-TEG) chip under zero bias condition were investigated to develop the inspection and localization technique of electrical failures in LSI chips without electrical contact, using a laser THz emission microscope (LTEM). The LSI-TEG chip measured in this work contains test circuits composed of p-n junctions and simple metallic line structures such as straight lines with different lengths, bent lines, and interrupted lines. It was found that THz emission waveforms and spectra were strongly influenced by metal line patterns under zero bias condition and its polarizations are parallel to the direction of the line where photocurrent flows. These characteristics are useful for the inspection of LSI chips with electrical failures such as open circuits and short-circuits by comparing the THz emission waveforms and the THz emission images between a normal chip and the tested one, without any electrical contact.