This month we feature part 2 of the “Optical lithography for Thin Film Head (TFH) manufacturing” series.

 

Part 2: "Stitching stepper/scanner fields to create TFH row bars”

In TFH processing, each read/write head or “slider” forms part of a “row bar”. The row bar is generally larger than a stepper or scanner field, so fields need to be stitched together. Once the processing is completed, the row bar is turned on its side and lapped to achieve the correct “stripe height”. To maximize yield, the stitch boundaries must have very low registration errors, specifically in the Y orientation (location B in diagram). This requirement also applies to the intrafield distortion (location A in the diagram).

In order to extend the TFH roadmap, both the stitching and lens distortion components had to improve, and this further accelerated the move from steppers to scanners for critical layers. The concepts and methodology, for optimizing stitching on ASML steppers, is thoroughly described in the SPIE paper: “Collinearity and stitching performance on an ASML stepper” by Michel van de Moosdijk et al.

For more information on TFH processing and stitching, please This e-mail address is being protected from spambots. You need JavaScript enabled to view it. at simaxlithography.com