Picosecond photoelectron microscope for high-speed testing of integrated circuits

The performance of devices and circuits is advancing at a rapid pace with the advent of submicron design ground rules and switching times under 50 ps. The requirements for probing the internal nodes of these ultra-fast, -small, and -dense circuits give rise to great challenges for high-speed electron-beam testing. In this paper, we review the steps which have allowed electron-beam testing to achieve simultaneously 5-ps temporal resolution, 0.1-μm spot size, and 3 mV/√Hz voltage sensitivity. The resulting newly developed instrument, called the picosecond photoelectron scanning electron microscope (PPSEM), is capable of measuring the state-of-the-art bipolar and FET circuits and also VLSI passive interconnects.