Design and implementation of an optical testing technique for VLSI chips using a potential-sensitive fluorescing dye

In this work, the viability of an optical testing technique for VLSI chips is demonstrated. A broad range of Testing Structures (TSs) were designed to accommodate a potential-sensitive, fluorescing dye. The use of this dye can provide massive observability of the tested chips. Emission spectra of two types of dye were obtained for different amplitudes of the applied electric field (E-field). Styryl-7 dye has exhibited a higher degree of fluorescence quench than D-4-ANEPPS dye. The sensitivity of fluorescence intensities for various TSs on the strength of the E-field was studied and used to determine the most effective TSs. Fluorescence measurements of the Pyramid and the Fork structures have exhibited the highest degree of fluorescence quench, 18.75%. Fluorescence measurements of effective TSs have shown a sufficiently high signal-to-noise ratio (SNR) to be of practical utility. Fluorescence measurements on the Pyramid structure have shown a SNR of 17 dB at the highest E-field excitation level. In addition, various TSs have characteristics that are suitable for testing either analog or digital circuits.