Interleaved acousto-optical device scanning for suppression of optical crosstalk

Patent metadata

Field	Value
Publication number	US-10060884-B2
Application number	US-201615184590-A
Country	US
Kind code	B2
Filing date	Jun 16, 2016
Priority date	Mar 15, 2013
Publication date	Aug 28, 2018
Grant date	Aug 28, 2018

Abstract

A method of scanning a sample includes simultaneously forming a plurality of co-linear scans. Each scan is formed by a sweep of a spot by an acousto-optical device (AOD). The co-linear scans are separated by a predetermined spacing. A first plurality of swaths are formed by repeating the simultaneous forming of the plurality of co-linear scans in a direction perpendicular to the co-linear scans. The first plurality of swaths have an inter-swath spacing that is the same as the predetermined spacing. The predetermined spacing can be a scan length or an integral number of scan lengths. A second plurality of swaths can be formed adjacent to the first plurality of swaths. Forming the second plurality of swaths can be performed in an opposite direction to that of the first plurality of swaths or in a same direction. An inspection system can implement this method by including a diffractive optical element (DOE) path after a magnification changer.

First claim

The invention claimed is:

1. An inspection system for inspecting a sample, the inspection system comprising:
a moveable platform system configured to secure said sample;
an illumination system configured to simultaneously generate a plurality of co-linear scans aligned along a co-linear scan line such that each scan is formed by a sweep of a spot by an acousto-optical device (AOD) along the co-linear scan line, and such that the plurality of co-linear scans are directed onto the secured sample and separated by a predetermined spacing; and
a controller configured to control the moveable platform system such that the secured sample is repeatedly stepped relative to the illumination system in a direction perpendicular to the co-linear scan line and in coordination with the generation of the plurality of co-linear scans such that a first plurality of swaths are formed by repeatedly generating the plurality of co-linear scans in a direction perpendicular to the co-linear scan line, the first plurality of swaths having an inter-swath spacing of the predetermined spacing.

2. The inspection system of claim 1 , wherein the illumination system is further configured to simultaneously generate the plurality of co-linear scans such that each scan has a scan length, and such that the predetermined spacing is equal to the scan length.

3. The inspection system of claim 1 , wherein the illumination system is further configured to simultaneously generate the plurality of co-linear scans such that each scan has a scan length, and such that the predetermined spacing is equal to an integral number of scan lengths.

4. The inspection system of claim 3 , wherein the AOD is programmable and configured such that said integral number of scan lengths is adjustable by adjusting a chirp of said programmable AOD.

5. The inspection system of claim 1 , wherein said controller is further configured to control the moveable platform system such that the plurality of co-linear scans form a second plurality of swaths adjacent to the first plurality of swaths.

6. The inspection system of claim 1 , wherein said controller is further configured to control the moveable platform system such that the plurality of co-linear scans form a second plurality of swaths adjacent to all of the first plurality of swaths except a bottom half of the first plurality of swaths.

7. The inspection system of claim 6 , wherein said controller is further configured to control the moveable platform system such that the second plurality of swaths are formed by moving the sample in an opposite direction to that utilizing during formation of the first plurality of swaths.

8. The inspection system of claim 6 , wherein said controller is further configured to control the moveable platform system such that the second plurality of swaths are formed by moving the sample in a same direction to that utilizing during formation of the first plurality of swaths.

9. A method comprising:
receiving a light beam from a laser and directing the light beam at various angles along an angular scan;
converting the angular scan to a linear scan;
receiving the light beam in the linear scan and generating a scan, the scan being a sweep of a spot, thereby generating a plurality of co-linear spots;
adjusting a magnification of the plurality of co-linear spots, thereby generating an adjusted plurality of co-linear spots;
duplicating the adjusted plurality of co-linear spots such that each adjacent pair of said co-linear spots are separated by a predetermined spot spacing, thereby simultaneously generating a set of co-linear scans aligned along a co-linear scan line and having a predetermined scan spacing there between; and
forming a first plurality of swaths by moving a sample in a direction perpendicular to the co-linear scan line, said moving said sample causing a plurality of sets of the co-linear scans to form adjacent sets of the co-linear scans, the first plurality of swaths having an inter-swath spacing equal to the predetermined scan spacing,
whereby performing said duplicating after said adjusting facilitates controlling a size of said plurality of co-linear spots without changing said predetermined spot spacing between each adjacent pair of said co-linear spots.

10. The method of claim 9 , wherein said moving the sample comprises stepping the sample in a direction parallel to the set of co-linear scans and then moving the sample in a direction perpendicular to the co-linear scan line such that the sets of co-linear scans form a second plurality of swaths adjacent to the first plurality of swaths.

11. The method of claim 10 , wherein said simultaneously generating said set of co-linear scans comprises sweeping said co-linear spots such that said first and second pluralities of swaths have a scan length, and such that the predetermined scan spacing is an integral number of said scan lengths.

12. The method of claim 11 , wherein said stepping the sample comprises moving the sample an adjustment distance in the direction parallel to the set of co-linear scans such that the second plurality of swaths are formed adjacent to the first plurality of swaths except for a bottom half of the first plurality of swaths.

13. The method of claim 10 , wherein said simultaneously generating said set of co-linear scans comprises sweeping said co-linear spots such that said first plurality of swaths have a first scan length and the second plurality of swaths have a second scan length that is different from the first scan length.

14. The method of claim 10 , wherein said forming the second plurality of swaths comprises moving the sample in an opposite direction to that utilized during forming the first plurality of swaths.

15. The method of claim 10 , wherein said forming the second plurality of swaths comprises moving the sample in a same direction to that utilized during forming the first plurality of swaths.

16. The method of claim 9 , wherein said duplicating the adjusted plurality of co-linear spots comprises diverting said adjusted plurality of co-linear spots either to normal incidence illumination path or an oblique incidence illumination path.

17. The method of claim 9 , wherein said duplicating the adjusted plurality of co-linear spots comprises diverting said adjusted plurality of co-linear spots to an oblique incidence illumination path.

18. The method of claim 9 , wherein said duplicating the adjusted plurality of co-linear spots comprises controlling a switching component 7 to direct the adjusted plurality of co-linear spots to one of a normal incidence illumination path and an oblique incidence illumination path.

19. The method of claim 9 , further comprising making adjustments to two independent axes of the light beam received from the laser before directing the light beam at said various angles.

20. The method of claim 9 , further comprising generating the light beam using a barium borate laser doubling crystal, and passing the light beam through a beam shaper having a slit.

21. The method of claim 9 , further including utilizing a pupil and one or more apodization plates placed in operative relation to the pupil to provide a predetermined transmission profile to the plurality of co-linear spots.

22. The method of claim 21 , wherein said utilizing the one or more apodization plates includes configuring the one or more apodization plates to provide a same transmission profile in an x axis and a y axis.

23. The method of claim 21 , wherein said ut

Assignees

• Kla Tencor Corp

Inventors

• Sullivan Jamie
• Cai Wenjian
• Churin Yevgeniy
• Johnson Ralph
• Brender Meier Yitzhak
• Wang Mark Shi
• Runyon Rex
• Cao Kai

Classifications

• G01N21/956

  Inspecting patterns on the surface of objects {(contactless testing of electronic circuits G01R31/308; testing currency G07D; manufacturing processes per se of semiconductor devices implementing a measuring step H10P74/20)} · CPC title

• G01N29/2418 Primary

  using optoacoustic interaction with the material, e.g. laser radiation, photoacoustics (photoacoustic cells G01N21/1702; measuring characteristics of vibrations by using radiation-sensitive means G01H9/00; acousto-optical conversion techniques for short-range imaging G01S15/8965; sound-producing devices using laser bundle G10K15/046) · CPC title

• G01N21/9501

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

• G01N2291/2697

  Wafer or (micro)electronic parts · CPC title

• G01N21/8806

  Specially adapted optical and illumination features · CPC title