Metrology
Auto-alignment and auto-calibration for capacitive displacement measurement
In order to perform a picometre precision position measurement over small ranges, capacitive sensing can be a good option. Positioning and alignment of the sensor relative to the measured object is however rather critical. A mechanism to reposition the sensor-electrode is therefore required. The stability of the final measurement may however not be compromised.
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- PhD student: ir. O.S. van de Ven (Oscar)
- Supervisor: ir. J.W. Spronck
- Promotor: prof.ir. R.H. Munnig Schmidt
- Duration: 2011-2015
In order to perform a picometre precision position measurement over small ranges, capacitive sensing can be a good option. Positioning and alignment of the sensor relative to the measured object is however rather critical. A mechanism to reposition the sensor-electrode is therefore required. The stability of the final measurement may however not be compromised.
A class of solutions that allow both motion and high position stability at rest uses friction clamping. The new solution found at TU Delft clamps the sensor-electrode with a ring of metallic fingers (a so-called spring-nest). The temperature of the individual fingers is controlled using electrical heaters on each finger. A net motion is, slightly simplified, generated as follows: For an upward motion all fingers are heated at the same time but they are cooled down individually. Since only one finger is cooling down at a given time, the electrode is held into place by almost all fingers and only this one finger will slide over the electrode surface. This sequence causes a net motion as is depicted in the figure below.
The current research within this project focuses on creating an optimal design by better understanding of the working of this motion mechanism but also exploring other actuation principles.
Supported by
Shape fitting: Application to the estimation of wafer chuck deformation
In wafer scanners - the machines that define the details of electronic chips - there is a need for highly accurate deformation measurements of the machine components during the chip manufacturing process. This thesis develops an estimation methodology, based on shape fitting principles, that aims at a low estimation error and addresses the specific requirements related to one of the components of a wafer scanner, the wafer chuck.
PhD Thesis: Shape fitting: Application to the estimation of wafer chuck deformation
