Multi-spot scanning collection optics

Patent metadata

Field	Value
Publication number	US-9546962-B2
Application number	US-201514619004-A
Country	US
Kind code	B2
Filing date	Feb 10, 2015
Priority date	Feb 12, 2014
Publication date	Jan 17, 2017
Grant date	Jan 17, 2017

Abstract

Disclosed are apparatus and methods for inspecting or measuring a specimen. A system comprises an illumination channel for generating and deflecting a plurality of incident beams to form a plurality of spots that scan across a segmented line comprised of a plurality of scan portions of the specimen. The system also includes one or more detection channels for sensing light emanating from a specimen in response to the incident beams directed towards such specimen and collecting a detected image for each scan portion as each incident beam's spot is scanned over its scan portion. The one or more detection channels include at least one longitudinal side channel for longitudinally collecting a detected image for each scan portion as each incident beam's spot is scanned over its scan portion.

First claim

What is claimed is:

1. system for inspecting or measuring a specimen, comprising:
an illumination channel for generating and scanning a plurality of incident beams to form a plurality of spots that scan across a segmented line comprised of a plurality of scan portions of the specimen; and
one or more detection channels for sensing light emanating from a specimen in response to the incident beams directed towards such specimen and collecting a detected image for each scan portion as each incident beam's spot is scanned over its scan portion, wherein the one or more detection channels include at least one longitudinal side channel for longitudinally collecting a detected image for each scan portion as each incident beam's spot is scanned over its scan portion, wherein the at least one longitudinal side channel is arranged to have an optical axis along which the detected image is collected and which is also parallel and coincident with a plane of the specimen or an image plane of the specimen.

2. The system of claim 1 , wherein the one or more detection channels include a first longitudinal side channel for longitudinally collecting a first plurality of detected images for the scan portions, a second longitudinal side channel for longitudinally collecting a second plurality of detected images for the scan portions, and a normal channel for collecting a third plurality of detected images for the scan portions, wherein the first longitudinal side channel is positioned opposite of the second longitudinal side channel.

3. The system of claim 2 , wherein the illumination channel includes a normal illumination sub-channel for generating and scanning a first set of the plurality of incident beams to contribute to the plurality of spots that scan across the plurality of scan portions of the specimen and an oblique illumination sub-channel for generating and scanning a second set of the plurality of incident beams to contribute to the plurality of spots that scan across the plurality of scan portions of the specimen.

4. A system for inspecting or measuring a specimen, comprising:
an illumination channel for generating and scanning a plurality of incident beams to form a plurality of spots that scan across a segmented line comprised of a plurality of scan portions of the specimen; and
one or more detection channels for sensing light emanating from a specimen in response to the incident beams directed towards such specimen and collecting a detected image for each scan portion as each incident beam's spot is scanned over its scan portion, wherein the one or more detection channels include at least one longitudinal side channel for longitudinally collecting a detected image for each scan portion as each incident beam's spot is scanned over its scan portion, wherein:
the one or more detection channels include a first longitudinal side channel for longitudinally collecting a first plurality of detected images for the scan portions. a second longitudinal side channel for longitudinally collecting a second plurality detected images for the scan portions, and a normal channel for collecting a third plurality of detected images for the scan portions, wherein the first longitudinal side channel is positioned opposite of the second longitudinal side channel,
the illumination channel includes a normal illumination sub-channel for generating and scanning a first set of the plurality of incident beams to contribute to the plurality of spots that scan across the plurality of scan portions of the specimen and an oblique illumination sub-channel for generating and scanning a second set of the plurality of incident beams to contribute to the plurality of spots that scan across the plurality of scan portions of the specimen, and
the first longitudinal side channel comprises:
a first front lens arranged for receiving first output beams that are scattered from the scan portions and directing such first output beams through a Fourier plane towards a first back lens,
the first back lens arranged for receiving and directing the first output beams towards a first sensor module, and
the first sensor module arranged for separately sensing the first output beams from the first back lens,

the second longitudinal side channel comprises:
a second front lens arranged for receiving second output beams that are scattered from the scan portions and directing such second output beams through a Fourier plane towards a second back lens,
the second back lens arranged for receiving and directing the second output beams towards a second sensor module, and
the second sensor module arranged for separately sensing the second output beams from the second back lens; and

the normal channel comprises:
output optics for collecting and directing the third set of output beams towards a third sensor module; and
the third sensor module arranged for separately sensing the third output beams.

5. The system of claim 4 , wherein:
the first longitudinal side channel further comprises:
a first optics element arranged for receiving the first output beams from the first front lens, spatially filtering portions of the first output beams at the Fourier plane, and directing the first output beams to the first back lens,

the second longitudinal side channel further comprises:
a second optics element arranged for receiving the second output beams from the second front lens, spatially filtering portions of the second output beams at the Fourier plane, and directing the second output beams to second back lens, and the normal channel further comprises:
a third optics element arranged for receiving and spatially filtering portions of the third output beams at the Fourier plane, and directing the third output beams to third sensor module.

6. The system of claim 5 , wherein the first and second optics elements each include an aperture having serrated teeth pointed perpendicular to an optical axis for controlling diffraction.

7. The system of claim 6 , wherein the serrated teeth are formed from two overlaid masks with serrated teeth so as to cover rounded portions of the teeth in each mask and to form non-rounded serrated teeth.

8. The system of claim 6 , wherein the first and second optics elements each include a plurality of pins that are independently movable to drop down into each aperture and selectively block noise, isolate signals, or block one or more diffraction spots.

9. The system of claim 4 , wherein the normal and oblique illumination sub-channels each comprise a magnifier changer.

10. The system of claim 9 , wherein:
the normal, first and second longitudinal side channels exclude a magnifier changer so as to have a fixed magnification for the first, second, and third output beams,
the normal and oblique illumination sub-channels each include a diffractive optical element (DOE) positioned after such sub-channel's magnifier changer, wherein the DOE's of the normal and oblique illumination sub-channels are arranged to generate the first and second set of incident beams, respectively, so that the first and second set of incident beams have a same center scan position at different magnifications; and
the first, second, and third sensor modules include a first, second, and third spot separator mechanism, respectively, that are sized and positioned to separately receive the first, second, third output beams, respectively, at a highest and lowest magnification without movement of such spot separator mechanism.

11. The system of claim 10 , wherein the normal and oblique illumination sub-channels each include a scan mechanism that is configured to sweep the first and second set of output beams across equally sized scan portions on the sample.

Assignees

• Kla Tencor Corp

Inventors

• Sullivan Jamie M
• Johnson Ralph
• Churin Evegeny
• Cai Wenjian
• Moon Yong Mo

Classifications

• G01N2201/1056

  Prism scan, diasporameter · CPC title

• G02B27/46

  Systems using spatial filters · CPC title

• G02B21/002

  Scanning microscopes (scanning near field optical microscopes G01Q60/18) · CPC title

• G02B21/0092

  Polarisation microscopes · CPC title

• G01N21/9501

  Semiconductor wafers (manufacturing processes per se of semiconductor devices implementing a measuring step H10P74/20) · CPC title