Signal analysis of a GaAs 1K-SRAM by high-speed e-beam testing

Abstract

This paper reports on the internal signal analysis of a GaAs 1K-SRAM by means of a high-speed e-beam test system developed in our laboratories. It allows noninvasive measurements on signal lines within the circuit with a very high spatial resolution (spot diameter: 0.5 μm) and a delay time resolution better than 3.5 ps. With this technique, it is possible for the first time, to our knowledge, to directly measure internal high-frequency signals of a GaAs LSI circuit, thus obtaining information which is inaccessible by other measurement techniques and allowing an extensive circuit analysis. For example, a measured time budget for the memory could be obtained. Furthermore, the comparison between measured and simulated waveforms enables the designer to directly evaluate the accuracy of the transistor and signal-transmission line models. The waveform measurements on the bit lines during the read process and inside an address buffer of the memory were analysed.