2-PHOTON OPTICAL BEAM-INDUCED CURRENT IMAGING THROUGH THE BACKSIDE OFINTEGRATED-CIRCUITS

Two-photon optical beam induced current (TOBIC) images were acquired t hrough the polished backsides of integrated circuits. An excitation be am with a photon energy below the band gan can traverse even thick sub strates virtually unattenuated. At the focus-and only there-two-photon absorption generates electron-hole pairs very efficiently when using a sub-picosecond light source. An additional advantage of TOBIC is a s ignificant increase in spatial resolution. With high numerical apertur e objective lense features smaller than 1 mu m are easily discernible. (C) 1997 American Institute of Physics. [S0003-6951(97)02644-2].