2009 R&D 100 Winner
Precise positions and displacements are crucial for reliable operation of high-precision mechanical stages used for optical and electron-beam lithographies, scanning electron microscopy, and next-generation extreme ultraviolet (EUV) lithography platforms. The shrinking size of semiconductor products pushed the need for high sensitivity position sensors well into the picoscale, beyond the scope of traditional sensors. Engineers in the Production Engineering Research Laboratory at Hitachi Ltd., Yokohama, Japan, developed the Interferometric Displacement Sensor, an ultracompact and highly sensitive displacement sensor based on common-path phase-shifting optical interferometry, which uses photonic crystal polarizers (PCPs) for the reference mirror and the phase shifter. It overcomes the problems seen with conventional interferometric sensors, particularly the sensitivity to ambient fluctuations, and achieves both ultra-compactness and high sensitivity using PCPs as the reference mirror and the phase shifter. Despite its compact size and competitive price point, it is capable of displacement sensitivity is as low as 40 picometers and electrical resolution of just 2.4 picometers.
Technology
Displacement sensor
Developer
Production Engineering Research Laboratory at Hitachi Ltd.
