US-12620548-B2 - Transmission electron microscopy

US12620548B2US 12620548 B2US12620548 B2US 12620548B2US-12620548-B2

Abstract

A transmission electron microscope is provided for imaging a sample. The microscope has a stage to hold a sample and an electron beam column to direct an electron beam onto a field of view on the sample. The electron beam column includes an electron beam source to generate an electron beam, and electron beam optics to converge the electron beam onto a field of view on the sample. The microscope also has a beam scanner to scan the electron beam across multiple fields of view on the sample. The microscope additionally has a detector to detect radiation emanating from the sample to generate an image. A controller is provided to analyze the detected radiation to generate an image of the sample.

Inventors

Christopher Su-Yan OWN
Matthew Francis Murfitt

Assignees

Mochii, Inc.

Dates

Publication Date: 20260505
Application Date: 20161031

Claims (20)

1 . A transmission electron microscope (TEM) for imaging a sample, the microscope comprising: a stage to hold and move a sample; an electron beam column to direct a substantially parallel electron beam onto the sample, the electron beam column defining an optic axis, the electron beam column comprising: an electron beam source to generate an electron beam along an optic axis, electron beam optics to condense the electron beam to form a substantially parallel electron beam at the sample in a TEM mode, and a beam scanner to shift the substantially parallel electron beam across multiple areas on the sample such that the electron beam is substantially parallel to the optic axis at the sample; beam optics to realign an electron beam emanating from the sample with the optic axis; a detector to detect the electron beam emanating from the sample to generate image data; and a controller adapted to automatically (i) define a plurality of supertiles that divide an area of the sample to be imaged, (ii) control the stage to move the sample relative to the beam between the supertiles, (iii) control the beam scanner to shift the beam across each of the multiple areas within each supertile in between stage movements, (iv) analyze the image data to generate a sub-image for each of the multiple areas on the sample, and (v) stitch together the sub-images to generate a larger image of the sample.
2 . A transmission electron microscope according to claim 1 , wherein the controller is adapted to control the beam scanner to sequentially shift the electron beam across at least four adjacent or overlapping areas on the sample, without moving the stage between the shifts.
3 . A transmission electron microscope according to claim 1 , wherein the controller is adapted to control the beam scanner to sequentially shift the electron beam across at least nine adjacent or overlapping areas on the sample, without moving the stage between the shifts.
4 . A transmission electron microscope according to claim 1 , wherein the controller is adapted to analyze the image to generate a feedback signal to control the beam scanner.
5 . A transmission electron microscope according to claim 1 , wherein the beam scanner comprises electromagnetic coils.
6 . A transmission electron microscope according to claim 1 , wherein the beam scanner comprises electrostatic deflectors.
7 . A transmission electron microscope according to claim 1 , wherein the controller is further adapted to re-tune one or more of the electron beam optics and the beam scanner between sequential areas.
8 . A transmission electron microscope according to claim 1 , wherein the controller is further adapted to move the stage between sets of shifts to a plurality of the areas.
9 . A transmission electron microscope according to claim 1 , wherein the controller is further adapted to select an area that has not previously been illuminated.
10 . A transmission electron microscope according to claim 1 , wherein the stitched-together image of the multiple areas is larger than a pixel array size of the detector.
11 . A transmission electron microscope according to claim 1 , wherein the controller is adapted to stitch together the sub-images to generate the larger image of the sample while the detector detects the electron beam emanating from the sample.
12 . A transmission electron microscope according to claim 1 , wherein the controller is adapted to generate aberration metadata for each of a plurality of the multiple areas within at least one of the supertiles and to use the aberration metadata to compensate for aberrations.
13 . A method for imaging a sample in a transmission electron microscopy (TEM) mode, the method comprising: holding a sample in a low-pressure environment; defining a plurality of supertiles that divide an area of the sample to be imaged; generating an electron beam along an optic axis; condensing the electron beam to form a substantially parallel electron beam at the sample in a TEM mode; moving the sample relative to the beam between the supertiles; between movements of the sample, shifting the substantially parallel electron beam across multiple adjacent or overlapping areas within each supertile on the sample such that the electron beam is substantially parallel to the optic axis at the sample; realigning an electron beam emanating from the sample with the optic axis; detecting the electron beam emanating from the sample to generate image data; analyzing the image data to generate a sub-image for each of the areas on the sample; and stitching together the sub-images to generate a larger image of the sample.
14 . A method according to claim 13 , comprising sequentially shifting the electron beam across at least nine adjacent or overlapping areas on the sample, without moving the stage between the shifts.
15 . A method according to claim 13 , comprising: analyzing the image to generate a feedback signal; and controlling the beam shifting based at least in part on the feedback signal.
16 . A method according to claim 13 , further comprising feeding a flexible tape, which comprises a plurality of samples deposited thereon, into the low-pressure environment.
17 . A method according to claim 13 , further comprising performing a re-tuning of an optical system between sequential areas.
18 . A method according to claim 13 , further comprising moving the stage between sets of shifts to a plurality of the areas.
19 . A method according to claim 13 , further comprising selecting an area that has not previously been illuminated.
20 . A method according to claim 13 , wherein stitching together the sub-images to generate the larger image of the sample comprises stitching together the sub-images while detecting the electron beam emanating from the sample.

Description

CLAIM FOR PRIORITY This application claims priority under 35 U.S.C. § 119(e) to Provisional Application 62/248,423, filed Oct. 30, 2015, which is incorporated herein by reference in its entirety. TECHNICAL FIELD This application relates to improvements in transmission electron microscopy. BACKGROUND Charged-particle beam microscopy can be used to image samples at very small dimensions. For example, charged-particle beam microscopy, which includes electron microscopy and focused ion beam microscopy, can be used to investigate samples at dimensions smaller than what is possible using solely light microscopy. Charged-particle beam microscopy may also reveal information that is not readily available through light microscopy, such as in relation to composition, crystallography, and topography of the sample. However, conventional charged-particle beam microscopes typically have a number of practical disadvantages in terms of speed and cost. Imaging numerous samples by conventional means may be slow and expensive. For example, sequential imaging of multiple samples may require frequent pumping cycles and recurring human manual intervention to insert samples. As another example, transmission electron microscopy (TEM) may require frequent and slow stage movements in order to image a large area of a sample or an entire sample, making it slow and therefore expensive to image large areas. Moreover, when imaging numerous samples, it may be difficult and labor-intensive to track the identity of each sample in relation to its digital image. Thus, it is desirable to provide charged-particle beam microscopy that can image numerous samples at relatively high speed and low cost. It is also desirable to be able to reliably and efficiently track the identities of each of multiple samples that are being imaged through charged-particle beam microscopy. SUMMARY In one embodiment, a transmission electron microscope is provided for imaging a sample. The microscope comprises a stage to hold a sample and an electron beam column to direct an electron beam onto a field of view on the sample. The electron beam column comprises an electron beam source to generate an electron beam, and electron beam optics to converge the electron beam onto a field of view on the sample. A beam scanner scans the electron beam across multiple fields of view on the sample, and a detector detects radiation emanating from the sample to generate an image. A controller is provided to analyze the detected radiation to generate an image of the sample. In another embodiment, a method is provided for imaging a sample. The method comprises holding a sample in a low-pressure environment, generating an electron beam, and converging the electron beam onto a field of view on the sample. The electron beam is scanned across multiple adjacent or overlapping fields of view on the sample, without moving the stage between a plurality of these scans. Radiation emanating from the field of view on the sample is detected to generate an image. The detected radiation is analyzed to generate an image of the sample. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments and aspects of the transmission electron microscopes described herein and, together with the description, serve to explain the principles of the invention. FIG. 1 is a schematic diagram of an example of an embodiment of a scanning electron microscope (SEM). FIG. 2 is a schematic diagram of an exemplary embodiment of a scanning transmission electron microscope (STEM). FIG. 3 is a schematic side view of an example of an embodiment of an optical column for a charged-particle beam microscope. FIGS. 4A and 4B are schematic side views of examples of embodiments of modular TEM columns. FIGS. 5A and 5B are examples of embodiments of acquisition systems combining an analyzer with a charged-particle beam microscope. FIG. 6 is a schematic diagram of communications between microscope hardware, a controller, and multiple clients. FIGS. 7A and 7B are top and side views of an example of an embodiment of a tape that is supporting samples and that contains identification codes for the samples, for transmission electron microscopy (TEM). FIGS. 8A and 8B are top and side views of an example of an embodiment of a tape that is supporting sample carriers with samples thereon and that contains identification codes for the samples, for TEM. FIG. 9 is a grayscale image of an example of an embodiment of a sample carrier that is a chip with a plurality of apertures, including apertures of different sizes. FIG. 10 is a top view of an example of an embodiment of a tape that is supporting multiple samples on each of a plurality of apertures, for TEM, w