Asml Netherlands B.v.

Marcus E J Boonman

Theodorus Marinus Modderman

Gerrit Johannes Nijmeijer

Jacob F F Klinkhamer

Frederik T E Heuts

Richard J H Du Croo De Jongh

Erik Roelof Loopstra

Thomas J M Castenmiller

Johannes C M Jasper

Nicolaas A A J Van Asten

Jacobus Gemen

Nicholaas A A J Van Asten

In an off-axis levelling procedure a height map of the substrate is generated at a measurement station. The height map is referenced to a physical reference surface of the substrate table. The physical reference surface may be a surface in which is inset a transmission image sensor. At the exposure station the height of the physical reference surface is measured and related to the focal plane of the projection lens. The height map can then be used to determine the optimum height and/or tilt of substrate table to position the exposure area on the substrate in best focus during exposure. The same principles can be applied to (reflective) masks.

Off-axis levelling in lithographic projection apparatus

Off-axis leveling in lithographic projection apparatus

Growing community of inventors

Veldhoven, Netherlands

Marcus E J Boonman