Direct Detection of Low-Energy Electrons With a Novel CMOS APS Sensor

Direct detection of low-energy electrons (500-2000 eV) with a novel back-thinned CMOS active pixel sensor (APS) is reported in this paper. The sensor was installed in a JEOL 6400F scanning electron microscope to quantitatively test its linearity and spatial resolution by a focused electron beam. The obtained results show good linearity at electron beam energy values from 500 to 2000 eV. The full-width at half-maximum spatial resolution was around 2 pixels, a limit set by charge diffusion in the epilayer. These results show that this CMOS APS sensor is appropriate for low-energy electron detection providing the benefits of direct detection for many applications.