Crenellated sample holder and sputter target for sample preparation in cryo electron microscopy applications

Patent metadata

Field	Value
Publication number	US-12488957-B2
Application number	US-202318193545-A
Country	US
Kind code	B2
Filing date	Mar 30, 2023
Priority date	Mar 30, 2023
Publication date	Dec 2, 2025
Grant date	Dec 2, 2025

Abstract

To reduce charging artifacts in electron microscopy, a notched ring of sputterable material can be situated about a sample surface. An ion beam can be directed through a notch at to sputter the sputterable material onto the sample surface. Sputtering can be performed after low-angle focused ion beam (FIB) milling at the same sample tilts. The sample can be rotated about an axis and sputtering performed at multiple rotation angles. Upon sputtering of the conductive coating, the sample can be reoriented and imaged. These steps can be repeated to produce a 2D image stack for 3D image reconstruction.

First claim

I claim:

1 . A sputtering target for a sample situated for charged particle beam milling in a charged-particle beam (CPB) instrument, comprising:
a conductive material defining an internal cavity adapted to receive the sample at a sample surface, the conductive material defining at least one window that provides a glancing angle CPB processing path to the sample surface as situated in the CPB instrument; and a first sputterable material situated opposite the at least one window to define a CPB sputtering path through the at least one window to the first sputterable material.

2 . The sputtering target of claim 1 , wherein the conductive material is a conductive ring that defines the internal cavity and that the at least one window is defined in the conductive ring.

3 . The sputtering target of claim 2 , wherein the at least one window is a slot in the conductive ring.

4 . The sputtering target of claim 3 , wherein the slot extends from a distal surface towards a plane associated with the sample surface.

5 . The sputtering target of claim 2 , wherein the at least one window is an aperture in the conductive ring.

6 . The sputtering target of claim 2 , wherein the conductive material is a sputterable material.

7 . The sputtering target of claim 6 wherein either one or both of the first sputterable material and the second sputterable material are one or more of chromium, molybdenum, aluminum, titanium, nickel, silver, copper, indium, gold, platinum, iridium, palladium, or combinations thereof.

8 . The sputtering target of claim 6 , wherein the one or both of the first sputterable material and the second sputterable material are one or more of stainless steel or gold.

9 . The sputtering target of claim 1 , wherein the conductive material is a conductive ring defining a plurality of windows.

10 . The sputtering target of claim 9 wherein each of the plurality of windows is a slot that extends from a distal surface of the conductive ring towards a sample plane.

11 . The sputtering target of claim 9 , wherein each of the plurality of windows is an aperture in the conductive ring.

12 . The sputtering target of claim 9 , wherein the plurality of windows is evenly situated about an axis defined by the conductive ring.

13 . The sputtering target of claim 11 , wherein the plurality of windows includes 3 or 5 windows.

14 . The sputtering target of claim 11 , further comprising a sample base configured to support the sample and insertable into the conductive ring.

15 . The sputtering target of claim 14 , wherein the conductive ring includes fastening means adapted to secure at least one of the sample base and the conductive ring along an axis of the CPB instrument.

16 . The sputtering target of claim 1 , wherein the conductive material is a crenellated conductive ring.

17 . A method comprising:
directing a CPB through a window in a sample mount to a sputtering target at a glancing angle with respect to a sample surface to sputter a conductive material on at least a portion of the sample surface; and directing a CPB through the window to the sample surface at a glancing angle to process at least a portion of the sample surface.

18 . The method of claim 17 , further comprising directing the CPB to a sputtering target through at least two windows in the sample mount to the sputtering target at the glancing angle with respect to the sample surface and then directing the CPB to process the sample surface.

19 . The method of claim 18 , further comprising:
rotating the sample surface and the sample mount; and directing the CPB through each of the at least two windows at a respective rotation angle.

20 . The method of claim 17 , further comprising directing the CPB to the sputtering target through an odd number of windows in the sample mount at the glancing angle.

21 . A sample holder for electron microscopy, comprising:
a crenellated circular conductive ring of a sputterable material defining an interior volume; and a conductive sample support adapted to retain a sample within the interior volume defined by crenellated circular conductive ring.

22 . The sputtering target of claim 6 , wherein the first sputterable material is the same as the second sputterable material.

Assignees

• Fei Co

Inventors

• Rue Chad

Classifications

• C23C14/3407

  Cathode assembly for sputtering apparatus, e.g. Target · CPC title

• H01J2237/31749

  Focused ion beam · CPC title

• H01J2237/081

  Sputtering sources · CPC title

• C23C14/14

  Metallic material, boron or silicon · CPC title

• H01J2237/20214

  Rotation · CPC title