We report on the fabrication and characterization of a monolithic electron field emitter device with focus lenses for multi-electron beam lithography and high density nano data storage. An array of individually addressable emitters was formed on oxidized etch pits of an SOI (Silicon on Insulator) wafer. Si active layer of the SOI (Silicon on Insulator) wafer. Si active layer of the SOI with gate hole array that self-aligned with the emitters was used as a common gate electrode. An array of cylindrical holes formed on the Si base of the SOI was used as a common lens electrode. The emitters, gate and lens array components are isolated each other by 2 μm-thick thermal SiO2 layers. For a single Pt emitter with gate hole of 2 μm diameter and anode voltage Vanod=0.7 kV, the emission current started at a gate voltage Vg=90 V and reached to 1.2 μA current and 0.84 mW beam power at Vg=300 V. The emission current was found to be stable with a fluctuation smaller than 10%/h. The emitter-gate and emitter-lens leak currents were found to be less then 1% compared with emission current. The focusing characteristic of the device was experimentally confirmed. A simulation work has shown that the beam with emission cone angle within 15° can be focused at a spot of 40 nm at a lens voltage, Vlens=-6 V.