Clearing the critical software path

Interview in Bits & Chips on ESI Concerto project with:

• Jeroen Voeten, TU/e

• Jos Vaassen, ASML

• Joost Gevers, ASML

• Bram van der Sanden, ESI

Clearing the critical software path

For a highly complex machine like the Twinscan to be able to operate smoothly, its system control should run without any unnecessary interruptions. Within the Concerto project, ASML, ESI (TNO) and TUE have developed a model-based methodology to analyze the software execution and keep computational tasks out of the critical path as much as possible. The partners see great potential for the approach to be widely adopted in the high-tech industry.

In ASML’s lithographic systems, the Twinscan stage simultaneously moves two tables, each holding a silicon wafer. While one wafer is being exposed to – deep or extreme – ultraviolet light containing the chip pattern to be printed, the other is measured by the machine’s metrology sensors to optimize alignment. The tables are propelled electromagnetically, allowing frictionless acceleration as high as 7G.

Every move the Twinscan stage makes has been precisely calculated by the system’s software. To ensure a smooth journey from A to B and prevent a wafer table from missing a turn, the computations need to be completed in time. “Imagine you’re on the highway, following the instructions of your navigation system,” ASML’s Jos Vaassen makes a comparison. “If the system takes too much time to calculate the route, you’re going to drive right past your exit. Likewise, we don’t want our scanners to miss a turn because our software is missing a deadline.”