Magneto-optical observation of surface currents in microelectronic circuits

A magneto-optical method is applied to observe surface electrical currents in microelectronic devices. We describe here the opportunity of direct experimental localization of latchup effect in complementary metal-oxide-semiconductor integrated circuits (ICs) by visualization of latchup current path in surface layer of ICs substrate. To observe currents greater than 10 mA the garnet films with both uniaxial and in-plane anisotropy are utilized. Optimal polarization geometry providing maximal visual contrast is calculated. Topologies of both solitary and two neighboring electrical currents are experimentally investigated. The sensitivity limit (minimal current surface density) of this method of magneto-optic visualization is estimated to be 0.1 mA/mu m. (C) 2000 American Institute of Physics. [S0021-8979(00)92308-9].