Feature: Sensors
Figures 1 and 2: During sawing, the single crystal rod is cut into thin wafer slices using an internal hole saw. Wire saws allow several slices to be cut from the bar at the same time. Here, non-contact sensors monitor the sawing processes
Even the smallest colour deviations of the concentration are reliably detected.
Lithography measurements Photolithography is central to the wafer manufacturing process. In the exposure step, the image of a photomask is transferred to the wafer surface. A photosensitive photoresist layer was previously applied to the wafer. Aſt er stabilising this resist layer, the actual exposure begins. Wafer lithography – especially
EUV lithography – is one of the most complex industrial manufacturing processes. In order to deposit structures in the single-digit nanometer range on the wafer, the machine and optical elements must be positioned and aligned with correspondingly high precision. Sensors are key here, since they handle nanometer-precise distance measurement in the positioning of the mask, the lens system and the wafer stages. High-resolution and long-term
stable measurements of the machine movements must be made when feeding and positioning the lithography mask. Capacitive displacement sensors are used in this process to monitor mask alignment, meeting precision requirements in the nanometer range. T eir modular design with multiple sensor channels and vacuum-compatible components enable use in numerous measurement tasks.
Figure 3: The ingot passes a measuring station with several laser scanners
Figure 4: Eddy current sensors monitor the axial movement of the saw blades
www.electronicsworld.co.uk February 2023 35
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