Precision positioning for electronics

Challenge

Producing circuits on silicon wafers relies on high-precision manufacturing processes that assemble electronic components to form multiple complete circuits on a single wafer. These are later separated into individual units for device assembly. To improve productivity and efficiency, wafer manufacturers are investigating methods to increase circuit production by fabricating more circuits on larger wafers.

During manufacture, positioning stages move wafers in 3D inside a vacuum chamber, as tiny details are etched or deposited onto them, to build-up electronic circuits. Achieving the high levels of position control required relies on accurate movement sensing techniques able to operate in challenging industrial environments. As more features are added to wafers, the distance between individual components shrinks and ever greater control over the stage’s nanometre movement are essential.

Interferometry is a laser-based technique for precisely determining distances in a single direction. It is based on splitting a laser beam into two, one beam travels to and is reflected back from a target on the item that moves, while the other acts as a reference. Recombining the two creates an interference pattern that can be used to accurately determine position changes. Currently multiple lasers are needed to generate information for movements in 3D, adding complexity and introducing significant measurement errors. To overcome these problems more powerful lasers able to generate multiple intense beams for 3D measurements, coupled with system simplification, are needed to enable industrial users to benefit from highly accurate interferometry measurements.