Maskless lithography systems
State-of-the-art interferometric displacement measurements are performed in high quality climatic chambers. Usually their range is around 300 mm, and their precision approximately 5 nm with a stationary target and 10 nm with a moving target.
The determination of the refractive index of air is a major source of uncertainty in state-of-the-art devices. Traditional weather stations can determine the average refractive index over a length of time accurately, but they can not react to the rapid changes of environmental conditions. Thus the real-time precision of interferometric measurements in air is limited by the temporal and spatial stability of the atmosphere. The AcWaCo method solves this problem, improving the real-time precision of interferometric measurements in air to the 1 nm level.
For this application AcWaCo uses the acoustic frequency of 200 kHz. The piezoceramic transducers have their own casing and are mounted directly on the interferometer, between the laser beams. The number of transducers depends on application, but typically three transducers are used. The sound waves reflect from the plane mirrors of the XY-stage.
The range of measurement, the speed of the stage and the measurement accuracy are interdependent. Improvement of one factor may lead to degradation of other(s). Your system's parameters are probably different from the ones described above, so please contact us and let us know your range, speed and accuracy requirements and their desired priority. Then we can evaluate the performance achievable with the given requirements.