Automated TEM sample preparation

Patent metadata

Field	Value
Publication number	US-10825651-B2
Application number	US-201916410774-A
Country	US
Kind code	B2
Filing date	May 13, 2019
Priority date	Nov 7, 2014
Publication date	Nov 3, 2020
Grant date	Nov 3, 2020

Abstract

Techniques are described that facilitate automated extraction of lamellae and attaching the lamellae to sample grids for viewing on transmission electron microscopes. Some embodiments of the invention involve the use of machine vision to determine the positions of the lamella, the probe, and/or the TEM grid to guide the attachment of the probe to the lamella and the attachment of the lamella to the TEM grid. Techniques that facilitate the use of machine vision include shaping a probe tip so that its position can be readily recognized by image recognition software. Image subtraction techniques can be used to determine the position of the lamellae attached to the probe for moving the lamella to the TEM grid for attachment. In some embodiments, reference structures are milled on the probe or on the lamella to facilitate image recognition.

First claim

We claim as follows:

1. A method for automated sample preparation in a charged particle beam environment, comprising:
acquiring a first image of a tip of a sample manipulation probe within the charged particle beam environment, wherein the charged particle beam environment includes one or more charged particle beam systems;
moving the sample manipulation probe;
acquiring a second image of the tip of the sample manipulation probe;
based on a difference between the first image and the second image, determining a position of the tip of the sample manipulation probe;
based on the position of the tip relative to a work piece within the charged particle beam environment, automatically moving the sample manipulation probe close to a thin section of the work piece, wherein the thin section of the work piece is attached to a bulk of the work piece by one or more small attachment structures;
severing the one or more small attachment structures so that the thin section is not supported by the bulk of the work piece;
automatically moving the thin section close to a sample grid for holding thin samples using the sample manipulation probe; and
attaching the thin section to the sample grid.

2. The method of claim 1 , wherein determining the position of the tip of the sample manipulation probe based on the difference between the first image and the second image comprises determining a position of the tip of the sample manipulation probe within an X-Y plane.

3. The method of claim 1 , further comprising:
acquiring a third image of the tip of the sample manipulation probe;
acquiring a fourth image of the tip of the sample manipulation probe, wherein at a time the fourth image is acquired the sample manipulation probe is in a different position than when the third image is acquired; and
based on a difference between the third image and the fourth image, determining a position of the tip of the sample manipulation probe in a Z direction.

4. The method of claim 3 , wherein the first image and the second image are acquired via a first charged particle beam system of the one or more charged particle beam systems, and the third image and the fourth image are acquired via a second charged particle beam system of the one or more charged particle beam systems.

5. The method of claim 1 , wherein determining the position of the tip of the sample manipulation probe based on the difference between the first image and the second image comprises:
identifying one or more fiducials on the tip of the sample manipulation probe based on the difference between the first image and the second image; and
determining the position of the tip of the sample manipulation probe is based at least in part on the one or more fiducials.

6. The method of claim 1 , determining the position of the tip of the sample manipulation probe based on the difference between the first image and the second image comprises:
applying an edge finder based on the difference between the first image and the second image; and
determining the position of the tip of the sample manipulation probe is based at least in part on one or more edges of the tip of the sample manipulation probe identified by the edge finder.

7. An apparatus for automated sample production in a charged particle system comprising:
a vacuum chamber for containing a work piece;
at least two charged particle beam columns for producing charged particle beams for imaging and operating on the work piece within the vacuum chamber;
a moveable sample stage for holding and moving the work piece within the vacuum chamber;
a charged particle detector for forming images from charged particles emitted from the sample upon impact of the charged particle beams;
a sample manipulation probe capable of submicron positioning;
one or more processors; and
a memory storing non-transitory computer readable instructions that, when executed by the one or more processors, cause the charged particle system to:
acquire a first image of a tip of the sample manipulation probe;
move the sample manipulation probe;
acquire a second image of the tip of the sample manipulation probe; and
based on a difference between the first image and the second image, determine a position of the tip of the sample manipulation probe.

8. The apparatus of claim 7 , wherein the instructions further cause the apparatus to use the position of the tip of the sample manipulation probe to initiate preparation of a TEM lamella from the work piece.

9. The apparatus of claim 7 , wherein determining the position of the tip of the sample manipulation probe based on the difference between the first image and the second image comprises determining a position of the tip of the sample manipulation probe within an X-Y plane.

10. The apparatus of claim 9 , wherein the first image and the second image are acquired via a first charged particle beam column of the at least two charged particle beam columns, and the instructions further cause the apparatus to:
acquiring a third image of the tip of the sample manipulation probe with a second charged particle beam column of the at least two charged particle beam columns;
acquiring a fourth image of the tip of the sample manipulation probe with the second charged particle beam column, wherein at a time the fourth image is acquired the sample manipulation probe is in a different position than when the third image is acquired; and
based on a difference between the third image and the fourth image, determining a position of the tip of the sample manipulation probe in a Z direction.

11. A method for automated sample preparation in a charged particle beam environment, comprising:
forming one or more fiducials on a tip of a sample manipulation probe within the charged particle beam environment, wherein the charged particle beam environment includes one or more charged particle beam systems;
based on the one or more fiducials on the tip, determining a position of the tip of the sample manipulation probe within the charged particle beam environment;
based on the position of the tip of the sample manipulation probe within the charged particle beam environment, automatically moving the sample manipulation probe close to a thin section of a work piece, wherein the thin section of the work piece is attached to a bulk of the work piece by one or more small attachment structures;
severing the one or more small attachment structures so that the thin section is not supported by the bulk of the work piece;
automatically moving the thin section close to a sample grid for holding thin samples using the sample manipulation probe; and
attaching the thin section to the sample grid.

12. The method of claim 11 , wherein determining the position of the tip relative to the thin section based on the one or more fiducials on the tip comprises:
acquiring a first image of the tip of the sample manipulation probe;
moving the sample manipulation probe;
acquiring a second image of the tip of the sample manipulation probe;
based on a difference between the first image and the second image, determining a position of the one or more fiducials on the tip of the sample manipulation probe.

13. The method of claim 11 , wherein determining the position of the tip relative to the thin section based on the one or more fiducials on the tip comprises:
acquiring an image of the tip of the sample manipulation probe;
determining a region of the image that includes the one or more fiducials; and
applying an edge finder to the region the image to determine the position of the tip relative to the thin section.

14. The method of claim 11 , wherein determin

Assignees

• Fei Co

Inventors

• Brogden Valerie
• Blackwood Jeffrey
• Schmidt Michael
• Trivedi Dhruti
• Young Richard J
• Miller Thomas G
• Routh Jr Brian Roberts
• Stone Stacey
• Templeton Todd

Classifications

• H01J37/3045 Primary

  Object or beam position registration · CPC title

• H01J37/28

  with scanning beams {(H01J37/268, H01J37/292, H01J37/2955 take precedence)} · CPC title

• H01J2237/31745

  for preparing specimen to be viewed in microscopes or analyzed in microanalysers · CPC title

• G01N2001/2873

  Cutting or cleaving · CPC title

• H01J2237/208

  Elements or methods for movement independent of sample stage for influencing or moving or contacting or transferring the sample or parts thereof, e.g. prober needles or transfer needles in FIB/SEM systems · CPC title