US 9,176,072 B2Granted

Dark field inspection system with ring illumination

AssigneeKLA-Tencor Corporation

InventorsGuoheng Zhao, Mehdi Vaez-Iravani, Scott Young, Kris Bhaskar

Life of this patent

Estimating the term…

Loading patent…

Abstract

A dark field inspection system that minimizes the speckle noise due to sample surface roughness can include a plurality of beam shaping paths for generating a composite, focused illumination line on a wafer. Each beam shaping path can illuminate the wafer at an oblique angle. The plurality of beam shaping paths can form a ring illumination. This ring illumination can reduce the speckle effect, thereby improving SNR. An objective lens can capture scattered light from the wafer and an imaging sensor can receive an output of the objective lens. Because the wafer illumination occurs at oblique angles, the objective lens can have a high NA, thereby improving optical resolution of the imaging sensor, and the resulting signal level.

Claims30

Dependent claims

A dark field inspection system comprising:

three or more beam shaping paths for generating a composite, focused illumination line on a wafer, each beam shaping path for illuminating the wafer at an oblique angle, the beam shaping paths forming a ring illumination, wherein each of the beam shaping paths includes an independent light source positioned to result in independent, random noise at a surface of the wafer and wherein each independent light source provides incoherent light with respect to each other independent light source, wherein each of the plurality of beam shaping paths includes a cylindrical lens, each cylindrical lens being tilted and rotated with respect to a light beam from its corresponding light source, and wherein each cylindrical lens has a cylindrical axis positioned parallel to an illumination line, an optical axis, and a b-axis perpendicular to both the cylindrical axis and the optical axis, wherein the b-axis is positioned perpendicular to the light beam from its corresponding light source;
an objective lens for capturing scattered light from the wafer;
and
an imaging sensor for receiving an output of the objective lens.

1 more element

Dependencies are inferred from the claim text.

Facts

Application: 12/919,760Filed 16 Jul 2010 · us provisional application
Priority: 22 Jul 2009
Published: US 2011/0169944 A114 Jul 2011
Granted: 3 Nov 2015
Term ends: Not estimatedThe source records don’t support an estimate.

Classification4 codes

G01N 21/9501
Characterised by the material or shape of the object to be examined: semiconductor wafers
G01N 21/8806
Investigating the presence of flaws or contamination: specially adapted optical and illumination features
G01N 2021/8822
Specially adapted optical and illumination features: dark field detection
G01N
Investigating or analysing materials by determining their chemical or physical properties