Projection lens arrangement

A charged particle multi-beamlet system for exposing a target using a plurality of beamlets, the system comprising:

• a system for generating a plurality of electron beamlets;
• first, second and third projection lens plates, each plate having a plurality of holes formed in it in an array and each plate having an electrode adapted to receive a control voltage, the first plate being furthest from the target and the third plate being closest to the target, and wherein three common control voltages are used, one common control voltage being applied to each plate;
• wherein the projection lens plates are adapted for forming an array of electrostatic projection lens systems at the location of the holes in the projection lens plates when control voltages are applied, one control voltage for each electrode, for generating a voltage difference between the electrodes, each projection lens system comprising projection lenses formed at corresponding holes of the projection lens plates so that each electron beamlet passes through a corresponding projection lens system;
• wherein the holes in the projection lens plates have sufficiently uniform placement and dimensions to enable focusing all of the beamlets onto the surface of the target using the control voltages, the control voltages of each of the projection lens plates being common to all of the projection lens systems;
• and
• wherein the common control voltage applied to the second plate is closer to the voltage of the electron source than is the common control voltage applied to the first plate, and the difference between the common control voltage applied to the third plate and the voltage of the target is about 0V.