Ion implantation into insulating layers results in an accumulation of surface charge. If this charge is excessive, microscopic but easily observed punch through craters can be produced. In addition, wafer charging can result in non-uniform implants. The effect is particularly insidious because monitor wafers without insulating layers will show no effect while adjacent product wafers with photoresist or oxide coatings may show gross non-uniformities. Well designed electron flooding will relieve both effects.