The microelectronics industry faces constant challenges in improving the quality and performance of electronic circuits, especially when addressing markets with high reliability requirements. One of the main challenges is to improve robustness of our technologies, making a rapid diagnosis of any parametric signature observed.

This paper describes the added value of using a massive e-beam inspection tool combined with CD SEM and contour analysis to accelerate the diagnostic of a process from a variability point of view. Massive CD and contour-based measurement have been used to investigate recurrent but nonsystematic signatures related to Poly Contact shorts risks.

Control plan definition for Critical Dimension (CD) and Overlay (OVL) is set up by performing CD and OVL windowing (modulated wafers in dose for CD and Translation or Scaling for OVL that are sent to yield). The variations are set so that yield failures are reached across the window. These wafers are typically densely measured on reference CD and OVL targets (dedicated metrology structures). The correlation of those measurements to yield leads to in-line specification limits and sampling definition. However, the statistical level of metrology information is not at the same level of yield EWS (Electrical Wafer Sorting) where all dies are measured. Massive e-beam Inspection changes the paradigm by enabling the measurement of every die on the wafer in a reasonable time and better anticipate probability of potential yield excursions.

Poly Contact shorts, is a situation caused by a contact edge getting too close to the gate edge. Process robustness consolidation can be particularly challenging due to the multiple sources of variability in the fabrication process, especially in the patterning process (photolithography and etching process). One of the very first actions in such situations is to perform a process variability breakdown: global (lot to lot, wafer to wafer, intra wafer, intra field) and local (LCDU and PCDU). From previous work it is also known that for critical lithography steps local components happen to be the largest contributors.

In this paper, massive ebeam technology is being used to characterize intra wafer and intra field component for CD and Overlay at die level (with the same spatial resolution as yield EWS map) while contour-based metrology from in-line CDSEM images gives complementary insight on local variability. Combining such “metrology” resources can be called metro-spection approach. This enables more exhaustive variability breakdown and time to decision and qualification is being accelerated. Finally, it will be shown that deploying a new process reducing local pattern CD variability is the most effective solution to increase robustness.