Mechanical vibrations and precision of conventional positioning systems are limiting factors for using nano-metrology tools directly in production environments. Vibrations cause relative motion between workpiece and inspection tool, which distorts measurements at the nanometer level. To enable robot based in-line nano-metrology, this paper proposes a metrology platform that is mounted on a robot arm and maintains a constant and precise relative distance to the workpiece by means of a control loop. This paper presents the mechatronic system design of a 1 degree of freedom (DoF) metrology platform for tracking a vibrating sample in the sub-nanometer range. By incorporating control relevant requirements in the mechanical and electrical design, which is supported by a dynamic error budgeting analysis, the implementation of a high bandwidth feedback loop is enabled. The metrology platform consists of a 1 DoF Lorentz actuator with gravity compensator, a low stiffness flexure-based guiding mechanism and a moving mass of 4 kg with high structural resonance frequencies. A high-bandwidth PD based controller that utilizes the signal of an interferometer is implemented for feedback control. Experiments show a tracking error of 4 nm RMS when exposing the sample under test to on-site measured vibrations, which complies with the dynamic error budgeting analysis. This demonstrates viability of the implemented mechatronic design for in-line metrology applications requiring sub-nanometer precision.
|Number of pages||9|
|Publication status||Published - 2017|
Bibliographical noteFunding Information:
We would like to acknowledge R. Deng, J.W. Spronck and R.H. Munnig Schmidt for providing the actuator design and for fruitful discussions. The project aim4np is financed by the European 7th Framework Programme , no. 309558 .
© 2017 Elsevier Ltd
Copyright 2017 Elsevier B.V., All rights reserved.
- In-process measurement
- Precision measurement
- Precision positioning