Improving reliability through nitrogen purge of carriers

Decreasing insulator thickness at many levels of recent technology nodes raises concern for reliability. We apply a stress test inline, using a specially designed structure. It was found that reliability was strongly affected by queue time between a dry and wet etch step of a spacer, likely due to remaining RIE induced damage. By applying nitrogen purge of the wafer carrier the susceptibility to failure can be completely eliminated. This points to a fail mechanism related to residual etch products.