US 6,686,994 B2Granted

UV compatible programmable spatial filter

AssigneeKLA-Tencor Technologies Corporation

InventorsDieter Wilk, Anlun Tang, Eric N. Vella, Rex Runyon, Jamie M. Sullivan

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Abstract

Disclosed are mechanisms for selectively filtering spatial portions of light emanating from a sample under inspection within an optical system. In one embodiment, a programmable spatial filter (PSF) is constructed from materials that are compatible with light in a portion of the UV wavelength range. In a specific implementation, the PSF is constructed from a UV compatible material, such as a polymer stabilized liquid crystal material. In a further aspect, the PSF also includes a pair of plates that are formed from a UV grade glass. The PSF may also include a relatively thin first and second ITO layer that results in a sheet resistance between about 100 and about 300 Ω per square.

Claims31

Dependent claims

An optical inspection system for detecting anomalies on a sample, comprising:

a light source for directing an incident light beam having a wavelength between about 340 nanometers and 400 nanometers onto a sample;
a programmable spatial filter (PSF) arranged in a path of light emanating from the sample in response to the incident light beam, the PSF being constructed from materials wherein when a voltage potential difference is applied to or removed from the materials, the materials have either an opaque property to thereby inhibit at least a first portion of the emanating light with a minimum extinction value of about 400:1 or have a transparency property to thereby transmit at least at least a second portion of the emanating light with a minimum transmission value of about 40 percent for the incident light beam;
a detector arranged within the path of the emanating light so that the second portion of the emanating light that is transmitted by the PSF impinges on the detector to thereby form an image of at least a portion of the sample;
and
an analyzer for receiving the image and determining whether there are any defects present on the sample portion by analyzing the received image.

2 more elements

An optical inspection system for detecting anomalies on a sample, comprising:

a light source for directing an incident light beam having a wavelength between about 340 nanometers and 400 nanometers onto a sample;
a programmable spatial filter (PSF) arranged in a path of light emanating from the sample in response to the incident light beam, the PSF comprising:
a pair of plates formed from a material that substantially transmits ultraviolet light and are sized to cover an aperture of the emanating light, the plates being ranged parallel to each other;
a first indium tin oxide (ITO) layer deposed on a first one of the plates;
a second plurality of ITO layer portions deposed on a second one of the plates, wherein the first ITO layer and the second ITO layer portions are positioned between the plates;
and
a polymer stabilized liquid crystal (PSLC) layer arranged between the first ITO layer and second ITO layer portions;
a detector arranged within the path of the emanating light so that the second portion(s) of the emanating light that are transmitted by the PSF impinges on the detector to thereby form an image of at least a portion of the sample;
and
an analyzer for receiving the image and determining whether tore are any defects present on the sample portion by analyzing the received image and for selectively applying a first voltage potential difference between at least a one of the second ITO layer portions and the first ITO layer so that an adjacent portion of the PSLC layer allow transmission of a first portion of the emanating light while another portion of the PSLC layer on which the first voltage potential difference is not applied inhibits a second portion of to emanating light through the PSF.

7 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/163,398Filed 4 Jun 2002 · us provisional application
Priority: 28 Mar 2002
Published: US 2003/0184739 A12 Oct 2003
Granted: 3 Feb 2004
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

G01N 21/95623
Inspecting patterns on the surface of objects: using a spatial filtering method
G02B 27/46
Diffraction optics , i.e. systems including a diffractive element being designed for providing a diffractive effect: systems using spatial filters
G02F 1/13775
Characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction…
G02F 2203/055
Wavelength dependent: wavelength filtering