A vacuum microdiode with a moving anode was fabricated by means of a new process requiring only two mask levels and only one critical etching step. The cathode, with a pyramidal shape, was made by anisotropically etching p silicon through a mask formed by the anode itself, which, at the end of the process, consists of a SiO2 suspended membrane supporting an Al layer. The process is compatible with standard complementary metal-oxide-semiconductor technology. I-V characteristics were measured under vacuum verifying also that the diode current is sensitive to visible light irradiation and to changes of the anode-to-cathode distance. A minimum anode-cathode distance of about 5000 Angstrom was obtained.