The emission uniformity of Si field emitter arrays (FEAs) with 1024 tips were evaluated by using electrostatic lens projector. Some surface modifications were applied to the Si FEA for improving the emission uniformity. A combination of CHF3 plasma and preheat treatments is very effective for cleaning the tip surface and for improving the uniformity of the work function distribution in the array. The number of working tips increased by a factor of 5 after the preheat treatment at the temperature of 450degreesC. For further improvement, high current pulses were applied to the FEA. The pulse drive is effective for improving the uniformity of the tip radius. By applying all of the treatment and driving methods, more than half of the array emitters could be activated even for small operating current of 5 muA. (C) 2003 American Vacuum Society.