In the semiconductor manufacturing process, defects often occur due to a marginal process window that affects the lithography and etch processes. These defects can result in bridging patterns and overlay issues, which consequently cause electrical shorts and partially etched vias producing electrical opens. SEM tools are used to find electrical failures through voltage contrast techniques. Manufacturers who fabricate with older process technology nodes often need to use their tool set more efficiently. This paper demonstrates an application of conventional SEM review with image to golden reference image inspection capabilities in Automatic Process Inspection (API ) mode to perform electrical inspections of die features.
This paper details how to use a SEM review tool to detect systematic electrical defects. This methodology can prove beneficial while monitoring and developing patterning techniques for a specific design rule by catching electrical shorts and opens that are more visible at a lower resolution inspection used in process monitoring. Outcomes of this effort show that conventional review SEM techniques, using known areas prone to process inconsistencies derived from features pushing the design rule, have the capability to effectively and efficiently monitor fabrication process while implemented in a production setting at process nodes between 100 to 200 nm. Using e-beam review tools offers several advantages and disadvantages. This paper demonstrates that by using a SEM review tool and selecting die locations for imaging that are more likely to fail electrically, manufacturers can use SEM automatic review capabilities more effectively and efficiently. The application developed may also be applied in fabrication facilities that have limited yield monitoring capacity.
This paper is a result of collaboration between Applied Materials and Microchip Technology Inc.