Wilton, Connecticut

Optical fabrication

Our Wilton colleagues make the science of polishing low-aberration optics an art, using advanced equipment only available at a few companies worldwide. Optics worth a quarter of a million euros are polished within two orders of magnitude more precisely than eyeglasses.

Wilton also specializes in optical contacting of very large surfaces. By achieving an extremely flat surface, two pieces of glass are fused together to form an indestructible bond, without any glue. This is done on a grander scale than any other industry.

ASML’s sensors must also withstand extreme wear and tear conditions. Wilton has more than 15 chambers that make up its robust coating capabilities. Its diamond-like carbon coating is like those used on military aircraft cockpit glass.

Mechatronic systems

In Wilton, we design, test and assemble two crucial modules of our lithography systems: the reticle handler and the reticle stage. These two modules move and hold the blueprint of the chip pattern that will be printed (known as a ‘mask’ or ‘reticle’).

The reticle handler operates with surgical precision to carefully move its priceless payload between locations in the machine, without dropping or distorting it. This sophisticated robot is in constant motion and must account for vibrations that are greater than its position accuracy requirements. It transfers the reticle within 20-25 micrometers of the same location, every time, yet the floor vibrates more than half a meter per second squared.

It’s a complex engineering challenge, which becomes increasingly difficult with ASML’s next-generation EUV lithography tools. Here a symphony of robots operates in parallel to move the reticle into and out of the vacuum chamber. For every one million movements, the reticle handler can’t generate more than one particle that lands on the reticle.

Once the reticle is received, the reticle stage securely holds it in place, without distorting or allowing it to move by more than a few picometers. The completely magnetically levitated stage accelerates at more than 15 g, more than three times the g-force experienced by a fighter jet pilot at takeoff, up to a constant velocity of more than three meters per second. It positions the reticle within fractions of nanometers in all six degrees of freedom at full speed.

The motors that propel the reticle stage generate more than 10,000 newton (N) of thrust force, which would be like dropping a car onto the reticle stage every time it accelerates. It does this billions of times over its lifetime without damaging itself or the reticle, or generating any particles that might contaminate the air.