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Method for an inline reticle particle detector

IP.com Disclosure Number: IPCOM000010172D
Publication Date: 2002-Oct-30
Document File: 3 page(s) / 93K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for an inline reticle particle detector. Benefits include improved functionality and improved reliability.

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Method for an inline reticle particle detector

Disclosed is a method for an inline reticle particle detector. Benefits include improved functionality and improved reliability.

Background

              Laser-based particle detection is used in cleanroom environments to quantify the count and size of particles in the ambient air. Particle detection equipment is available for the detection of particles from 65 nm to 1000 nm with a resolution of 5 nm.

              Any particles that reach an extreme ultraviolet (EUV) photomask undetected adversely affect device yield. The risk of undetected particles directly impacts throughput and cost by requiring increased mask inspection.

      Conventional lithography tools use a thin transmissive membrane (pellicle) located in a plane parallel with the photomask surface. The pellicle prevents particles from reaching the surface. The pellicle is installed post inspection and protects the reticle during handling and exposure. Particles landing on the pellicle are out of the focus range of the optics system and do not impact imaging.

      No pellicle solution exists for EUV lithography. It is a reflective technology and no pellicle material is available. Current development work has focused on eliminating particle generation, rather than detection.

General description

              The disclosed method uses a device to detect particles in vacuum transiting a plane parallel to a photomask.

              The key elements of the method include:

•             Laser-based system with cylindrical lens that propagates along a plane parallel to a reticle

              solid state

•             Vacuum-compatible detectors to detect scatter light from particles transiting the plane

•             Wavelength selection to avoid conflict with other...