milling in step 220 is preferably performed without the use of an etch assisting gas by not using a gas in step 220 the time interval at which the ion beam can return to each pixel that is the refresh time can be decreased because it is unnecessary to wait for additional gas molecules to be adsorbed onto the substrate surface the ion beam dwell time can also be increased because it is not limited by the amount of adsorbed gas available at the dwell point the repair time can therefore be significantly reduced in one test repair time was reduced by fifteen percent in step 220 the holes in the chromium were milled to between about seventy percent and about ninety percent of the chromium thickness it is desirable to mill a large portion of the chromium depth in step 220 because milling is relatively rapid but the depth of milling should not be so great that the chromium is thinned to a point at which a significant amount of gallium is implanted in the substrate a value in the of 50 to 95 of the depth may be useful in many applications and a value outside this range may be useful in some applications the optimum pixel spacing and depth of milling in step 220 will depend on the beam size and properties of the mask such as the absorber and substrate materials and the thickness of the absorber in step 224 the ion beam is directed to pixels within the entire defect area including frame area 320 and 321 using a pixel spacing sufficiently small to produce a smooth floor on the milled area if the.