Tomography-assisted TEM prep with requested intervention automation workflow

Patent metadata

Field	Value
Publication number	US-11004651-B2
Application number	US-201916576565-A
Country	US
Kind code	B2
Filing date	Sep 19, 2019
Priority date	Sep 6, 2017
Publication date	May 11, 2021
Grant date	May 11, 2021

Abstract

Provided is a process for lamella thinning and endpointing that substitutes a series of automated small angle tilts for the motions in the conventional endpointing sequence. STEM images or through-surface BSE scans are acquired at each tilt. The results are analyzed automatically to determine feature depths, and an intervention request is made requesting a user decision based on marked-up images and summary information displayed.

First claim

We claim as follows:

1. A method comprising:
milling a layer of material from one major lateral side of a workpiece, the workpiece including two major lateral sides;
acquiring an image at each tilt orientation of a small-angle tilt series, the small-angle tilt series including a plurality of tilt orientations;
identifying one or more features in each of the images;
applying metrology to determine respective depths of the one or more features from at least one of the major lateral sides;
requesting an operator intervention in the process by (I) displaying prepared images with measured depths displayed and identified, (II) displaying measured thickness of the workpiece lamella, and (III) presenting a limited choice intervention menu with a first option to mill away a layer on the same major lateral side of the workpiece previously milled and a second option to flip the workpiece and then mill away a layer on the opposing major lateral side of the workpiece;
receiving an operator choice through the limited choice intervention menu; and
based on the operator choice, either flipping the lamella or presenting the previously milled major lateral side of the workpiece lamella toward the ion beam, milling a layer of material from the presented side of the workpiece.

2. The method of claim 1 , wherein the small-angle tilt series includes no more than two projections.

3. The method of claim 1 , wherein the images are STEM projections.

4. The method of claim 3 , wherein identifying one or more features in each of the images includes:
aligning the STEM projections; and
determining tomographic reconstruction of the STEM projections based on the aligned STEM projections.

5. The method of claim 4 , further including preparing a set of tomographic image projections based on the tomographic reconstruction, wherein the prepared images are based on the tomographic image projections.

6. The method of claim 3 , wherein the STEM projections are High Angle Annular Dark Field (HAADF) STEM images.

7. The method of claim 3 , wherein the STEM projections are bright-field (BF) STEM images.

8. The method of claim 1 , wherein identifying one or more features in each of the images includes determining depths of the one or more features from both lateral sides of the workpiece.

9. The method of claim 1 , wherein requesting an operator intervention includes transmitting a notification over a network.

10. The method of claim 1 , further comprising ion beam milling the workpiece from a larger workpiece.

11. The method of claim 1 , further comprising mounting the workpiece to a moveable sample mount.

12. The method of claim 1 , in which preparing the images in (e) further includes identifying pre-determined features by extracting features in the tomographic reconstruction with image processing, and identifying the extracted features based on expected feature dimension data and automated metrology on the extracted features.

13. The method of claim 1 , wherein the images and milling are performed inside a dual-beam charged particle microscope.

Assignees

• Fei Co

Inventors

• Alvis Roger Louis
• Landin Trevan R
• Clark Greg

Classifications

• H01J37/304 Primary

  Controlling tubes by information coming from the objects {or from the beam}, e.g. correction signals · CPC title

• H01J2237/2802

  Transmission microscopes · CPC title

• H01J2237/31749

  Focused ion beam · CPC title

• H01J2237/2815

  Depth profile · CPC title

• H01J2237/31745

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