IFC HDP Via Etch Process Development (Jun. 1998 +)
Present status:
- Preprocess recipe was improved to be more effective at keeping chamber free of polymer residue between wafers; presently, the capability exists to restore a coated chamber through plasma cleans only (if necessary) - when problem first developed, an acid bath wet clean was used
- The best process points achieved with use of H-addition have been matched without reliance on a hydrogen-containing gas; the best emissions reduction achieved earlier this summer was ~65%, but not with good process characteristics; now 70-80% is attainable with good profile and etch rate
- Etch rate and profile characteristics match or exceed those of the reference process
- However, while photoresist selectivity is presently acceptable for via etch application (~3:1), it still falls short of target set by C3F8 reference process (ᡂ:1)
- An iodine-sputtering mechanism is believed to be responsible for the resist erosion despite a high degree of polymerization, as evidenced by significant polymer deposits inside feature accompanied by poor bulk resist selectivity under certain process conditions