Characterization of metal profile notching as a result of electron shading in a high-density plasma etcher

Abstract

In today's high volume manufacturing of semiconductor devices large amounts of capital are required to establish and operate production facilities. Therefore, IC manufacturers are now "cloning" processes to enable products and technologies to be transferred to other sites to provide optimum production flexibility. Unfortunately, these processes cannot always simply be lifted and "dropped" into a new facility, even if identical tools are used. During a process and product transfer from one Motorola fab to another the metal etch process exhibited some unexpected complications as severely undercut metal profiles were seen on certain products. Although initially not very well understood the reason for this defect turned out to be ion deflection due to electron shading. This paper will show that by applying the relevant statistical tools this mechanism can be controlled or even completely eliminated. Adjustment ofplasma parameters will result in a process which yields excellent profile control.