ASML
Graduation assignment: Analyze the projection grating module used in the ASML level sensor
Introduction
This is a graduation assignment for a master's student in a master student in Mechanical Engineering, (Applied) Physics, Material science or a related discipline who is interested in redesigning the projection grating adjustment module which is part of ASML machines.
Job Mission
Chips are produced in a series of etching and deposition steps. The pattern that is etched is typically created using an ASML machine. In order to create nanometer structures, the position and local height of the wafer has to be known accurately. Therefore, each wafer is first measured before it is exposed (patterned). Recent ASML machines are able to process two wafers simultaneously, whereby one wafer is measured while the other wafer is exposed (patterned).
During measurement, the local height map of the wafer is measured using a so called level sensor. The measured height map is used to assure correct focus at the expose side.
For correct operation of the level sensor, several optical elements (lenses, mirrors) have to be aligned after assembly of the sensor into the scanner.
You will be working with the Mechanical Measurement Functions group to find the root-cause for hysteresis in the current projection grating, a critical part of the level sensor. This hysteresis limits the performance of the level sensor module. In order to improve this, you will:
- Investigate and analyze (potential) sources of hysteresis in the module
- Design and manufacture an improved proto design setup
- Use your setup to prove your proposed solution(s)
Your main deliverable is a redesign of the projection grating adjustment module, whereby the hysteresis is decreased by a factor of 2 or more.