Low temperature RTP for BCB curing

Rapid thermal processing (RTP) applications are rapidly expanding from the original processes, typically performed above 1000 °C (e.g., post-implant annealing and silicon oxidation) to lower temperature applications such as cobalt and nickel silicide formation with process steps performed as low as 200 °C. The original lamp-based (i.e., “cold wall”) RTP systems, despite their pyrometry-related issues, are [1] still used, even in this low temperature regime. Another problem related to this approach occurs when processing materials exhibit significant outgassing, such as boron-phosphosilicate glass (BPSG). The outgassed vapour can condense on the cold chamber walls and change the light transmission characteristics of the quartz window. This can cause a process shift, uniformity change and will likely increase maintenance. In this paper, an alternative, hot wall approach, based on convection and conductive heat transfer is evaluated for low-temperature curing and annealing of benzocyclobutene (BCB) for high speed digital and microwave applications [2].