Fast Settling Servo Drives Speed Wafer Testing

Gain scheduling by profile enables the system to rapidly and automatically adjust parameters to support high-speed positioning with minimum settling time

Semiconductor fabrication requires a complex sequence of time-consuming steps using highly sophisticated and expensive equipment. The reason the microelectronics industry can deliver massive computing power at reasonable pricing is because of batch processingæthe ability to fabricate hundreds of identical chips simultaneously on wafers the size of dinner plates. The economics of batch processing only hold if those hundreds of chips are operational,
however. As a result, component testing is essential to support process control, quality assurance, and even standards compliance.

Testing begins with the patterned wafer, to identify any bad chips before they undergo expensive packaging steps. With individual devices measuring just millimeters across, test equipment needs to be precise, repeatable, and above all, accurate. Test systems also need to have the smallest possible footprint, because space in a semiconductor fab is always at a premium. Finally, the testing process needs to be fast enough to keep up with the output of the
microlithography machines. When semiconductor test-equipment manufacturer Proaut Technology GmbH began to upgrade its PMA wafer-testing series, the goal was to reach 40,000 components per hour. The company met its goal using high-performance, high-efficiency servo drives from Elmo Motion Control.