FSI puts the lid on a single-wafer cleaning system

by Debra Vogler, Senior Technical Editor, Solid State Technology

Nov. 3, 2008 – FSI International has unveiled a new single-wafer cleaning system, called Orion. The system has a closed chamber design the company says addresses several cleaning-related issues on the critical path for 32nm and 22nm technologies — in particular, reduction of material loss during photoresist stripping after ultrashallow implants, and the elimination of material loss and galvanic corrosion in high-k metal gates and copper interconnects with metal-containing capping layers.

According to Scott Becker, VP of marketing and product management at FSI, the closed-chamber design excludes oxygen, which is responsible for material loss and corrosion in high-k metal gates and new copper interconnects with cobalt and other metals in the capping layers. “It also permits the use of volatile, highly-reactive chemistries [e.g., ViPR technology] for single-step, all-wet stripping of the highly implanted photoresist created during the fabrication of 32nm devices,” noted Becker. “By eliminating ashing, we not only reduce material loss by a factor of ten, but also reduce the cycle time, process complexity, and the number of tools and process steps.”

Development of a single-wafer tool that could perform the ViPR process came about thanks to customers’ request, Becker told SST. The company will not divulge the catalyst it uses, but together with a process temperature “much higher than 220°C — as opposed to a standard wet bench process temperature <150°C, or <180°C for a typical single-wafer approach -- these two factors enable a reaction rate (on the Orion platform) that is 4000× faster than the reaction rate of standard all-wet photoresist stripping processes.

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Use of a spray bar (see figure below) gives greater wafer coverage than a single point nozzle with more efficient chemical and water usage, as it delivers an energetic spray of chemicals and water as the wafer is rotated under the bar, Becker told SST. This bar extends a little bit beyond the wafer’s edge and the closed chamber enables high-energetic/high-temp chemistry processes without risk to personnel or tool safety from fumes and splashing, he said.

The tool’s design accommodates multiple chamber types and permits the addition of modules. Over the last two years, the company has validated system performance on development systems in the field; production systems are now available. — D.V.

The integrated spray bar in FSI’s Orion system. (Source: FSI)
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