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Technology Revolutionizes Semiconductor Industry ChamberLink rewrites industry rules on how to create motion within a vacuum chamber Creating motion in a vacuum typically requires either a rotary feedthrough, with ferrofluid or O-rings to seal the shaft, or a magnetic feedthrough, which does not provide a posit ive connection. While functionally acceptable, each of these mechanisms has drawbacks. Any kind of seal, whether magnetic fluid or rubber type, presents the chance of seal failure (i.e. leakage), which can compromise the vacuum's integrity or become a source of particulate contamination. Magnetic couplings have no seals but their driving and driven ends are physically separated and rely on the force of magnetic flux through the chamber wall. This lack of a direct connection is a weak torque transmitter that allows for slippage. The ChamberLink is a combination feedthrough and servo actuator created by Harmonic Drive Technologies, Peabody, MA. It has no shaft seals, yet the driven side in the chamber is positively, precisely, and powerfully connected to the driving side outside of the chamber. The device operates using the principles of harmonic drive gearing, combining a precise harmonic drive servo actuator with a rotary feedthrough in one stainless steel device. One part does double-duty as a working gear and as part of the chamber wall. While designed to provide precise rotary motion inside a vacuum chamber, it is driven from outside the chamber, allowing the motor to avoid the chamber heat. Plus, the motor does not need to be vacuum compatible. The unique design keeps the motor and input elements on the chamber's ambient side, while the speed-reduced and torque-multiplied output shaft moves on the vacuum side. This design provides a number of convenient benefits, including the ability to remove the motor during bakeout, or any other time, without risking the loss of vacuum. A precursor to this device was originally designed for use in a space launch vehicle and later to power wheels on a lunar rover, says Mark Silverman, manager of Harmonic Drive Technologies' semiconductor sales division. "We realized that if this could work in outer space--the ultimate and harshest vacuum environment--then it certainly could be applied to vacuum environments in the semiconductor industry." Wafer handling is one such area. "Current wafer handling applications involve a device turning a container that holds the wafer--rotating it or moving it. Once you're into vacuum handling, the only thing moving is the wafer," he explains. The ChamberLink can be customized, which is critical since the current and potential applications for the drive have varied greatly. "We believe there are a multitude of applications the device could be used for, and will work closely with the engineering staff to customize a design that suits their needs," says Silverman. -- KC For more information: Circle 536 - Harmonic Drive Technologiesor connect directly to their
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