Characterization of ion implanter electron flood guns using charge pumping and threshold voltage measurements

In this paper, three successive generations of ion implant electron flood devices are compared with regard to their wafer charging characteristics. Gate oxide damage of CMOS antenna transistors is used as a relative indicator to quantify the degree of implant charging. Charge pumping and threshold voltage measurements are used as parametric damage indicators. Our results show that the largest charging occurs when the first generation device, a secondary electron flood (SEF), is used for beam neutralization. The latest generation of electron flood gun designed to inject relatively low energy electrons provides the best control of wafer charging.