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.

A six degree of freedom, magnetically levitated metrology platform is proposed and implemented to enable nano-scale measurements directly in a production environment by providing vibration isolation. The metrology platform maintains a constant distance between sample and nano-metrology tool, forming a nano-scale laboratory environment directly in the production line. This paper presents the design of the proposed metrology platform. Tracking of the sample is achieved by using six position sensors, a six degree of freedom actuator and feedback control. Experimental results demonstrate positioning of the platform in six degrees of freedom at a bandwidth of 35 Hz in the translational directions and at a bandwidth of more than 15 Hz in the rotational directions, respectively. This results in a tracking error that is smaller than 50 nm rms. This paper denotes the first successful attempt for six degree of freedom vibration isolation to enable in-line nano-metrology.

Measuring properties at the nanometre scale such as topography, morphology and roughness within a production line becomes increasingly important for quality control and process monitoring tasks. In a production line, ground vibrations are transmitted to the sample and the inspection tool, corrupting nanoscale measurements by affecting the distance between inspection tool and sample. To enable nanometre scale measurements a mechanism is needed that keeps this distance constant. This paper describes the concept and experimental results of a metrology platform that tracks the sample for nanoscale inspection. The nano inspection tool is carried by the metrology platform and is artificially coupled to the movement of the sample by using a feedback controller. A one degree of freedom experimental setup was built for demonstrating tracking performance. The implemented closed loop control achieves disturbance rejection with a bandwidth of 410 Hz and reduces emulated on-site vibrations from ±500 nm down to ±9 nm, showing significant reduction of external vibrations.