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US 10,705,026 B2Granted
Scanning differential interference contrast in an imaging system design
AssigneeKLA Corporation
InventorsAndrew Zeng, Xuan Wang, Steve Xu
Life of this patent
Estimating the term…
Abstract
The inspection system includes an illumination source, a TDI-CCD sensor, and a dark field/bright field sensor. A polarizer receives the light from the light source. The light from the polarizer is directed at a Wollaston prism, such as through a half wave plate. Use of the TDI-CCD sensor and the dark field/bright field sensor provide high spatial resolution, high defect detection sensitivity and signal-to-noise ratio, and fast inspection speed.
Claims20
An apparatus comprising:
- at least one illumination source;
- a stage configured to secure a wafer;
- a TDI-CCD sensor;
- a dark field/bright field sensor;
- a field stop in a light path from the illumination source;
- a polarizer in the light path, wherein the polarizer is configured to pass P polarized light and reflect S polarized light;
- a Wollaston prism in the light path, wherein the Wollaston prism forms the P polarized light and the S polarized light;
- a correction lens optic in the light path;
- a mirror in the light path that receives the P polarized light and the S polarized light from the Wollaston prism;
- and
- an objective lens assembly in the light path, wherein the correction lens optic, the mirror, and the objective lens assembly are configured to focus the P polarized light and the S polarized light onto the stage, wherein the P polarized light and the S polarized light are separated in a shear direction of the Wollaston prism, and wherein the P polarized light and the S polarized combine at the Wollaston prism.
8 more elements
A method comprising:
- generating a light beam using an illumination source;
- directing the light beam from the illumination source through a field stop;
- directing the light beam from the field stop through a polarizer;
- directing the light beam from the polarizer to a Wollaston prism;
- directing the light beam from the Wollaston prism to a correction lens optic;
- directing the light beam from the correction lens optic to a mirror;
- directing the light beam toward a wafer on a stage through an objective lens assembly, wherein the correction lens optic, the mirror, and the objective lens assembly are configured to focus P polarized light and S polarized light from the Wollaston prism onto the stage, wherein the P polarized light and the S polarized light are separated in a shear direction of the Wollaston prism;
- splitting the light beam reflected from the wafer on the stage with a dichroic mirror into a first light beam and a second light beam;
- receiving the first light beam with a dark field/bright field sensor;
- combining the P polarized light and the S polarized light of the second light beam at the Wollaston prism;
- and
- receiving the second light beam from the Wollaston prism with a TDI-CCD sensor.
9 more elements
Dependencies are inferred from the claim text.