US 4,999,510 AGranted

Apparatus for detecting foreign particles on a surface of a reticle or pellicle

AssigneeNikon Corporation

InventorsFuminori Hayano, Kazunori Imamura, Sunao Murata, Kinya Kato

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Abstract

An apparatus for detecting foreign particles on a surface of a reticle or pellicle comprises an optical system through which a light beam forms a light spot on the surface. The surface and the light spot are shifted relatively so that the light spot scans the surface. Light detectors receive light scattered by a foreign particle and directed in different directions, respectively, and generated photoelectric outputs by which the presence of the foreign particle is discriminated. Beam diameter and scanning speed are varied to provide the most effective operation for particles of different sizes.

Claims7

Dependent claims

An apparatus for detecting foreign particles on a surface of a reticle or pellicle, comprising:

a supplying means for supplying a light beam which forms a light spot on said surface;
a scanning means for shifting said surface and said light spot relatively so that said light spot scans the surface;
a plurality of light detectors for receiving light scattered by a foreign particle on said surface and directed in different directions, respectively, and for generating photoelectric outputs, respectively;
changing means for changing the diameter of said light beam;
and
a discriminating means for discriminating the presence a foreign particle on said surface on the basis of each of said photoelectric outputs.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application: 07/427,365Filed 27 Oct 1989 · continuation in part
Priority: JP 62-1715529 Jan 1987
Granted: 12 Mar 1991
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

G03F 1/62
Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles…
G01N 21/94
Investigating the presence of flaws or contamination: investigating contamination, e.g. dust
G03F 1/84
Auxiliary processes, e.g. cleaning or inspecting: inspecting
G01N 2021/4721
Multiangle measurement: using a PSD

Family

Serial148,691Parent of this continuation-in-part · filed 26 Jan 1988
US 4,999,510 AThis patent

From the US filing history. Foreign family members aren’t listed.

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