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Product Briefing Outline: Aerotech’s WaferMax T rotary stage was originally designed for the demands of precision wafer inspection; however, due to its low height design it can be used in a wider range of tool applications where high-throughput production performance with high levels of precision are required especially when space and access are limited. The WaferMax-T rotary stage has full 360-degree rotation and a certified accuracy of +/-5arc/sec.

Problem: WaferMax stages are well matched to applications requiring very tightly synchronized axis-to-axis and axis-to-sensor motion and where very accurate incremental steps must be combined with precise speed such as optical line scanning. The direct drive rotary is only 50mm tall, handling limited space environments with easy chuck integration.

Solution: A standard 25mm aperture allows for easy pass-through of vacuum lines where limited rotation is required. If continuous rotation is necessary, an optional single or dual port rotary union can be incorporated. The tabletop includes a standard mounting pattern that allows for easy wafer-chuck mounting. To maximize positioning performance, the WaferMax T utilizes Aerotech’s S-series brushless, slotless motor. This motor has all the advantages of a brushless direct-drive motor — no brushes to wear, no gear trains to maintain, and high acceleration and high speeds. Since it is a slotless, ironless design, there is zero cogging, meaning that there is no torque ripple. A 10,000-lines-per-revolution encoder results in 0.065 arc sec resolution. A 2048 line option is also available. The motor and high-performance rotary encoder are directly coupled to a common shaft.

Applications: WaferMax T is designed to handle contoured motion, smooth scan velocity, or precise incremental steppping. The low inertia and zero backlash make the WaferMax T suitable for applications requiring frequent directional changes. Combined load rating for WaferMax Z-Theta solutions is around 3kg, and, for applications beyond the recommended load, there are a number of vertical and rotary stage options that can be used.

Platform: The WaferMax-T rotary stage has a thick-walled, precision ground shaft and high-stiffness angular contact bearings for improved wobble performance, high moment rigidity and reduced friction. With its directly coupled, high-accuracy rotary encoder, the stage will provide a working resolution of up to 0.065arc-sec with the 10,000-lines-per-revolution encoder option. WaferMax stages may be used on their own or in combination with other Aerotech submicron, linear x and y stages along with associated drives and motion controls.

Availability: Summer 2007 onwards.