Investigation and elimination of sphere defects

Successful development and implementation of new device technologies requires optimization of all parameters which can impact final device yield. Key areas of focus are transistor performance characteristics, device module integration, process integration, and process-induced defects. The performance of the manufacturing process in each of these areas determines the overall manufacturability of the process. As device geometries are reduced, understanding and minimizing the sources of process-induced defects is critical to achieving and maintaining high device yields. This paper describes some of the defect reduction activities performed during the evaluation of two new device technologies (T1, T2). In-line inspections were implemented in key process modules to monitor for process and integration-related defect issues. During this monitoring, intermittent defect issues were found in the isolation module. The defects appeared as point defects in optical microscope review. SEM characterization indicated the defects are circular pattern defects, typically ~0.3 to 0.5 microns in size. Experiments were performed to identify the defect source and determine the mechanism of defect formation. The solutions implemented to eliminate this issue are presented