The performance of submicron devices and circuits for the coming decade is advancing at a rapid pace. The emerging requirements to probe the internal nodes of these ultrafast, small and dense circuits give rise to great challenges for high‐speed electron beam testing. In this paper, we review the steps of advancing the electron beam testing to achieve simultaneously: 5‐ps temporal resolution, 0.1‐μm spot size, and 3 mV/Hz1/2voltage sensitivity. The newly developed instrument, called the picosecond photoelectron scanning electron microscope, is capable of measuring the state‐of‐the art bipolar and field‐effect transistor circuits.