# US 8,785,850 B2 · Charging of a hole-free thin film phase plate

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 8,785,850 B2
- Document ID: US8785850B2
- Status: Granted
- Kind: B2
- Application number: 12/930,749
- Filed: 2011-01-15
- Published: 2011-07-21
- Granted: 2014-07-22
- Earliest claimed: 2010-01-19
- Assignees: National Research Counsel of Canada; JEOL Ltd.
- Applicants: Marek Malac; Marco Beleggia; Masahiro Kawasaki; Ray Egerton
- Inventors: Marek Malac; Marco Beleggia; Masahiro Kawasaki; Ray Egerton
- Web page: https://patentgrep.com/patent/US8785850B2

## CPC

- H01J 37/295: Electron or ion diffraction tubes
- H01J 37/04: Arrangements of electrodes and associated parts for generating or controlling the discharge, e.g. electron-optical arrangement or ion-optical arrangement {(H01J37/32009, H01J37/32623, H01J37/3266, H01J37/32697 take precedence; electron or ion-optical systems for localised treatment of objects H01J37/3007)}
- H01J 37/26: Electron or ion microscopes; Electron or ion diffraction tubes
- B82Y 35/00: Methods or apparatus for measurement or analysis of nanostructures
- H01J 2237/2614: Holography or phase contrast, phase related imaging in general, e.g. phase plates
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES

## Abstract

New methods for phase contrast imaging in transmission electron microscopy use the imaging electron beam itself to prepare a hole-free thin film for use as an effective phase plate, in some cases eliminating the need for ex-situ fabrication of a hole and reducing requirements for the precision of the ZPP hardware. The electron optical properties of the ZPP hardware are modified primarily in two ways: by boring a hole using the electron beam; and/or by modifying the electro-optical properties by charging induced by the primary beam. Furthermore a method where the sample is focused by a lens downstream from the ZPP hardware is disclosed. A method for transferring a back focal plane of the objective lens to a selected area aperture plane and any plane conjugated with the back focal plane of the objective lens is also provided.

## Claims

### Claim 1

A method of phase contrast imaging with a transmission electron microscope TEM including a sample holder, an objective lens assembly, one or more intermediate lenses, and an object plane, wherein the method comprises:
placing a hole-free thin film at a back focal plane of the objective lens assembly, or at a plane conjugate thereto;
preparing the hole-free thin film for phase contrast imaging using an electron beam having at least a component thereof focused to a small area on the hole-free thin film at a center of the electron beam; and
subsequently imaging a sample in the sample holder by focusing unscattered waves of the electron beam onto a small area on the hole-free thin film, while scattered waves are distributed across the hole-free thin film to impart a phase offset between the scattered and unscattered waves.

### Claim 2 (depends on 1)

The method of claim 1 wherein preparing the hole-free thin film comprises using the electron beam to modify electro-optical properties of the hole-free thin film to increase the efficiency of phase transfer by the TEM by charging.

### Claim 3 (depends on 1)

The method of claim 1 wherein the electron beam has an incident electron energy between 100 eV and 1 MeV and the hole-free thin film has a thickness selected to apply a phase delay of π/2+nπ, where n is an integer.

### Claim 4 (depends on 1)

The method of claim 1 wherein preparing the hole-free thin film comprises using the electron beam to modify electro-optical properties of the hole-free thin film to increase the efficiency of phase transfer by the TEM by charging.

### Claim 5 (depends on 1)

The method of claim 1 wherein the transmission electron microscope is a transmission electron microscope, wherein the electron beam is Kohler illumination having a convergence angle of up to about 1 mrad.

### Claim 6

A method for transmission electron microscope imaging, comprising:
inserting a hole-free thin film into the transmission electron microscope at a back focal plane of the objective lens or a plane conjugate thereto, wherein said transmission electron microscope comprises at least one lens downstream from the hole-free thin film;
applying fields at objective lenses of the transmission electron microscope to focus the electron beam such that unscattered waves from a sample in the transmission electron microscope travel throughout a centre of the hole-free thin film, and scattered waves from the sample pass through the remainder of the hole-free thin film; and
adjusting condenser settings of the TEM to improve contrast within the image.

### Claim 7 (depends on 6)

The method of claim 6 wherein a lens downstream from the hole-free thin film is used to focus an image of the sample.