| Popis: |
With the growing complexity of I-line and DUV photolithography processes, defect monitoring and yield improvement is becoming more critical and challenging. In addition to product wafer scans, reliable unpatterned wafer scans, with their advantage of much quicker feedback time for tool qualification and/or process monitoring must be developed and implemented. Especially with the more wide spread use of the newer chemically amplified resist, a high sensitivity, easy to review and trouble-shoot monitor is essential. A laser scanning unpatterned wafer defect detection tool was used to scan developed unpatterned photoresist coated wafers. Defect recipe creation for detecting these defects involved using the size of a calibration media was not used since it is not at all representative of the way real process defects scatter light. A novel, non-destructive media was not used since it is not at all representative of the way real process defects scatter light. A novel, nondestructive unpatterned wafer review method was used to actually review the defects using darkfield microscopy, and to determine real defects from false calls. From this work we were able to detect defect process signatures and defects that were related to the develop dispense configuration. Darkfield microscopy revealed the defects were indeed developer related since they appeared as liquid spot type defects and/or residue. Subsequent use of this method has been established as an excellent troubleshooting method to finding and fixing photo defect issues. The methods and results of this work will be discussed. |
