Yield Engineering Systems (YES) stainless steel cassettes are ideal for polyimide bake, BCB cure, copper anneal, as well as other cure processes.YES cassettes can be used throughout the clean room in semiconductor fabrication processes where plastic or quartz cassettes are inappropriate or do not perform as well.
YES cassettes are designed to SEMI specifications and mate to most plastic cassettes, so they can be used on all automated vertical or horizontal transfer systems. (Note: our low profile cassettes, designed for easier manual loading of cassettes inside YES systems, are not compatible with automated vertical transfer systems). All cassette designs, including low profile, are compatible with manual push or slide transfer.
YES cassettes are designed to achieve accurate wafer support with minimal mass. Temperatures remain uniform throughout heat up and cool down applications minimizing hot/cold spots due to heat sinking. Cassettes are placed with the wafers vertically in YES-450PB Series ovens to facilitate the laminar flow process. The result is a better, more uniform process.
The outer surface of a quartz cassette vitrifies (changes over time due to heat). This causes two problems: particle introduction increases and cassettes become more brittle with each process run, until eventually the boat (cassette) breaks.When a quartz cassette breaks inside a process oven, it creates particle issues that are time consuming and costly to fix.
Also, the quartz boat is an insulator.When the wafer becomes statically charged there is nowhere for the charge to go and the charged wafers begin to attract particles.Stainless steel cassettes are a conductor which allows the static charge on the wafer to dissipate when placed on a grounded surface.