Harris uses SMIF without Class 1 conditions
Harris Semiconductor has achieved rapid rampup of its Mountaintop, PA, power MOS wafer fab, and is using SMIF technology without Class 1 cleanrooms to hold down costs.
Unlike many fabs equipped with SMIF minienvironments, Fab 8 does not keep its cleanrooms at Class 1. This approach results in substantial savings, both in facilities and operations. "If the fab were a Class 1 ballroom, it would require three to four times the amount of air-handling equipment we`re using," noted David Hollock, 200-mm Wafer Fab Project Leader, Manufacturing.
Mike Wieder of Air Filtration Management Inc., Bethlehem, PA, a pre-building consultant, added, "This fab subscribes to total isolation technology. They maximized the benefit of that. They realized that the environment around needs to be clean - to be controlled - but we do not need to overdesign and compensate for the Class 1 environment. And they took those attributes and were, in turn, able to capitalize on the downsizing of the other parts of the environment and look to the efficiencies."
Fab 8`s 24,500-ft2 cleanroom was designed at Class 1000 with its minienvironments certified at Class 1 or sub-Class 1. The fab was certified at better than Class 100. Seventy percent of the tools are SMIF-integrated, while the remaining 30 percent are enclosed in adaptive SMIFs and minienvironments. An attached maintenance area of about 5500 ft2 also operates at Class 1000. Fab technicians can go back and forth between the maintenance area and the fab environment without de-gowning.
The fab boasts windows and generous expanses of glass throughout the facility. The site itself includes an additional 40 acres of woods for the next expansion. A building automation system monitors 3000 points throughout the fab, automatically paging the appropriate maintenance mechanic. The ballroom-type diffusion area uses BTI furnaces, and Harris is currently working with Asyst software on a tool integration project, which will probably take another 9-12 months, and is about 30 percent complete. The company expects to "just about eliminate throughput/yield problems," says Burrell, with lot validation and automatic recipe downloading.
- Susan English-Seaton, Cleanrooms magazine