Voltage contrast defect inspection of contacts and vias for quarter micron devices

Wafer inspection techniques, which mainly detect the pattern defects and particles using the optical system, have been widely adopted in the ULSI manufacturing process for a process optimization and a process and field level monitoring. However, with the recent aggressive scaling of the ULSI design rule, a capture rate of the killer defects by the conventional optical inspection system is being degraded because of the spatial resolution limitation and the increase of invisible defect contribution. Especially, the detection of invisible killer defects such as an electric contact failures, open and short failures, which can not be detected by the optical inspection system, is being strongly required. In recent studies, these kinds of defect were tried to be detected using the voltage contrast image of the scanning electron microscope (SEM) technique. Therefore, these are called as "voltage contrast defects". In this paper, we investigated the voltage contrast defect detection focusing on the electrical failure of contacts and vias using the SEM technique.