IFC HDP Via Etch Process Development (Jun. 1998 +)
Solutions to 1997 issues :
- High 1-iodoheptafluoropropane etch rates have allowed for large window for optimization with respect to other key parameters
- Addition of hydrogen-containing gas and other process changes have improved resist selectivity
- Changing process window to conditions where less polymerization occurs inside the feature was found to improve via profile
New process issues found in 1998:
- Excessive reliance on hydrogen addition can lead to significant buildup of polymer in the chamber, which can be difficult to clean with standard preprocess
- Addition of hydrogen to process appears to result in formation of larger quantities of CHF3, partially offsetting gains made in emissions reduction vs. baseline process
- It is still a challenge to achieve significant improvement in bulk resist selectivity (ɯ:1) without etch stopping