JP2011187267A - Sample holder and multi-beam system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sample holder capable of carrying out a thin film processing and a STEM observation by using a pretilt holder without reloading the sample in a sample holder and a multi-beam system. <P>SOLUTION: The sample holder to be used for a multi-beam system is provided with: a transmission electron detector 25 on an extension line where electron beams of an electron optical system pass through the sample 23; and a sample holder on which the sample is so arranged that a processing state in a secondary electron image and a scanning transmission electron image can be observed in at least two kinds or more simultaneously or alternately. The sample holder is composed of: a mesh 23b for fixing the sample processed down to a prescribed thickness; a chip-on-cartridge 30 for setting the sample processed on the mesh; and a sample-holder part 40 on which the chip-on-cartridge is fixed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a sample holder and a multi-beam system, and more particularly to a sample holder and a multi-beam system that can perform thin film processing and STEM observation without changing the sample.

  In a transmission electron microscope (TEM), a sample is irradiated with an electron beam from an electron gun, and a transmission electron microscope image (TEM image) or diffraction image formed by an electron beam transmitted through the sample is an electron beam optical axis. A TEM image is observed by a fluorescent plate or the like arranged on the top.

  The sample observed with such a transmission electron microscope is made thin so that the irradiated electron beam can be transmitted. A focused ion beam (FIB) processing apparatus is used as the sample preparation apparatus, and FIG. 3 is a diagram showing a sample preparation procedure using the focused ion beam processing apparatus.

  In this case, first, as shown in (a), a sample block 1 cut out in a L shape from a sample material (for example, a semiconductor substrate) is attached to a half-cut single-hole mesh 2 formed in a C shape. . Since the sample block 1 is as small as about 2 mm, the sample creator picks the sample block 1 with tweezers and attaches it to the single-hole mesh 2. Thus, the sample 3 is formed by the sample block 1 and the single hole mesh 2.

  Next, as shown in (b), the sample 3 is set in the chip-on cartridge 4. At this time, the sample 3 is pressed by the leaf spring 5 and fixed to the chip-on cartridge 4. Since the single-hole mesh 2 is as small as about 3 mm and the sample 3 is small, the sample creator picks the sample 3 with tweezers and sets it in the chip-on cartridge 4.

  Next, as shown in (c), the chip-on cartridge 4 is set in the sample holder 6 for the FIB processing apparatus. Since the length of the chip-on cartridge 4 is about 5 cm, the sample creator is configured so that four sample-on cartridges 4 can be set in the sample holder 6 for the FIB processing apparatus.

  Next, the processing apparatus sample holder 6 is mounted on a FIB processing apparatus (not shown). Then, the focused ion beam is scanned on the sample block 1 of the sample 3, and FIB processing (thin film processing) is performed on the sample block 1. By this thin film processing, a thin film portion 1a is formed on the sample block 1 as shown in FIG.

  When the FIB processing for all the sample blocks (in this case, four sample blocks) is completed, the sample creator takes out the FIB processing apparatus sample holder 6 from the FIB processing apparatus. Then, the sample creator picks and removes one chip-on cartridge 4 from the FIB processing apparatus sample holder 6 by hand, and the chip-on cartridge 4 is removed as shown in FIG. Set to the tip of 7. The TEM sample holder introducing portion 7 is formed in a rod shape, and the chip-on cartridge 4 is detachably attached to the tip of the introducing portion 7.

  A conventional apparatus of this type is a sample holder mounted on a sample observation apparatus or an ion beam irradiation apparatus, which is a mounting section having a rod-shaped introduction section, one end and the other end, and one end of which is the above-mentioned There is known a sample holder having a leaf spring for fixing a sample, which is a mounting portion detachably attached to the leading end of the introduction portion and a sample holding portion detachably attached to the other end of the mounting portion. (For example, refer to Patent Document 1).

  In addition, the energy of the ion beam used for finishing processing is lowered, the incident angle to the sample is optimized according to the sample shape, and the change in the element of interest in the STEM image is monitored to detect the end point of processing An apparatus is known (for example, see Patent Document 2).

Japanese Patent No. 4351103 (paragraphs 0008 to 0011, FIG. 4) Japanese Unexamined Patent Publication No. 2007-193777 (paragraphs 0011 to 0016, FIGS. 1 and 2)

  In the conventional apparatus, after the thin film processing is completed, it is transferred to the STEM observation dedicated holder. For this reason, the sample that has undergone thin film processing is once taken out of the vacuum, placed on the STEM holder, and then set in the chamber again for STEM observation. In this case, the sample has a diameter of 3 mm or less, which is a complicated operation. Due to complicated operations, erroneous operations such as dropping the sample or damaging the sample frequently occur.

  The present invention has been made in view of such problems, and provides a sample holder and a multi-beam system that avoids the trouble of sample mounting and does not drop or damage the sample. It is aimed.

In order to solve the above-described problems, the present invention has the following configuration.
(1) According to the first aspect of the present invention, in a multi-beam system including an electron optical system and an ion optical system in the same chamber, when a thin film is processed as a sample for TEM or STEM observation, the transmission electron detector is used as an electron optical. A multi-unit having a sample holder portion on which an electron beam of the system is provided on an extended line that transmits the sample, and the sample is arranged so that at least two kinds of secondary electron images and scanning transmission electron images can be observed simultaneously or alternately. A sample holder for use in a beam system,
A mesh for fixing a sample processed to a predetermined thickness;
A chip-on cartridge for setting a sample fixed to the mesh;
A sample holder portion to which the chip-on cartridge is attached,
The chip-on cartridge is inclined at a predetermined angle with respect to the sample holder portion.

  (2) The invention according to claim 2 is a multi-beam system comprising an electron optical system and an ion optical system in the same chamber, wherein the electron beam optical system and the ion optical system are placed in the chamber at a constant angle α. The optical axes intersect with each other at a coincidence point, and the sample holder according to claim 1 is arranged at the coincident point, and ion beam processing and STEM image observation are performed on the arranged sample. It is characterized by that.

  (3) The invention according to claim 3 is characterized in that the transmission electron detector is arranged on an extension line of an electron beam optical axis through a stage.

The present invention has the following effects.
(1) According to the invention described in claim 1, a mesh for fixing a sample processed to a predetermined thickness, a chip-on cartridge for setting the sample processed into the mesh, and a sample holder to which the chip-on cartridge is attached And a stage for setting a sample holder to which the chip-on cartridge is mounted, and the chip-on cartridge is mounted at a predetermined angle with respect to the sample holder, so that the processing of the sample and the processed sample Observation can be performed at the same time, avoiding the complexity of sample mounting, and providing a sample holder that does not drop or break the sample.

  (2) According to the invention described in claim 2, by using the sample holder described in claim 1, it is possible to avoid complicated mounting of the sample and to prevent the sample from dropping or being damaged. A system can be provided.

  (3) According to the invention described in claim 3, a sample processed by FIB can be directly observed using STEM.

It is a figure which shows the structural example of the principal part of this invention. It is a figure which shows the attachment procedure of a sample. It is a figure which shows the conventional sample preparation procedure using a focused ion beam apparatus. It is a figure which shows the procedure which sets the sample shown in FIG. 3 to a transmission electron microscope.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a configuration example of a main part of the present invention. In the figure, 20 is EOS (electron optical system) and 21 is IOS (ion optical system). As the EOS, for example, a scanning transmission electron microscope (STEM) is used, and as the IOS, for example, a focused ion beam apparatus (FIB) is used. These EOS 20 and IOS 21 are provided in the same chamber (not shown) and constitute a multi-beam system.

  Reference numeral 23 denotes a sample arranged on the optical axis of the EOS 20. The configuration of the sample 23 is the same as that shown in FIG. The sample 23 is processed in advance to have a width of 10 μm or less. The sample 23 is irradiated with incident electrons from the EOS 20 and is irradiated with an ion beam from the IOS 21. Reference numeral 23a denotes a thin film portion formed of the IOS 21.

  Reference numeral 22 denotes a secondary electron detector that detects secondary electrons emitted from the sample 23. Reference numeral 24 denotes a stage for holding the sample 23. In the middle of the stage 24, a transmission electron beam passage 24a for passing a transmission electron beam is formed. Reference numeral 25 denotes a STEM detector that detects transmitted electrons that have passed through the sample 23. As the STEM detector 25, for example, a converter that converts an electron beam into an electric signal, for example, a photoelectron image multiplier (PMT) is used. The operation of the apparatus configured as described above will be described as follows.

  In a multi-beam system having EOS and IOS in the same chamber, as a sample for TEM or STEM observation, a transmission electron detector 25 is provided on an extension line through which the electron beam of EOS 20 passes through the sample 23 when processing a thin film. A sample holder is provided for arranging samples so that at least two kinds of secondary electron images (reflected electron images) and scanning transmission images can be observed simultaneously or alternately.

  In the multi-beam system, the EOS 20 and the IOS 21 are fixed to the chamber so as to have a constant angle α, and their optical axes intersect at a coincident point. Here, the co-incident point is a point where the same point can be seen at different angles. The sample 23 is arranged at the coincident point to perform ion beam processing and SEM observation.

Since the transmission electron detector 25 is disposed on the extended line of the electron beam optical axis via the stage 24, for example, a sample 23 pre-processed to a thickness of about 50 μm or less is previously inclined at an angle α formed by the EOS 20 and the IOS 21. If there is a holder, it becomes possible to observe a transmission electron image at the same time when processing a thin film. FIG. The present invention includes a multi-beam stage 42 (described later) and a sample fixing portion 41 (described later). The stage 42 meshes with the sample holder unit 40 (details will be described later). In this case, the sample fixing portion 41 is inclined by an angle α from the optical axis normal.

  S0 is a diagram showing a sample pre-processed into a mesh and a mesh holding the sample. In the figure, reference numeral 23 denotes a pre-processed sample, and this sample portion is fixed to the mesh 23b with epoxy or the like. In this case, the sample 23 is processed in advance to a thickness of several tens of μm or less by mechanical polishing or the like. A sample 23 pre-processed into a mesh such as brass or molybdenum is attached to the mesh 23b. Reference numeral 23 a denotes a thin film portion previously formed on the sample 23.

  The sample and mesh formed in this way are attached to the chip-on cartridge 30 shown in S1. A sample 23 is attached to the chip-on cartridge 30, and the sample 23 is attached to the chip-on cartridge 30 as shown in S2. The sample 23 and the mesh 23 b are placed at a predetermined position of the chip-on cartridge 30.

  Here, a plate spring 31 for holding the sample 23 is attached to the chip-on cartridge 30. If the plate spring 31 is fixed with a fixing screw 33 shown in S3, the sample 23 is fixed to the chip-on cartridge 30. Will be. S4 indicates a sample holder. Reference numeral 40 denotes a sample holder portion for holding the sample 23, and reference numeral 41 denotes an attachment portion for attaching the chip-on cartridge 30 attached to the sample holder 40. The mounting portion 41 constitutes the sample fixing portion 41 described above.

  42 is a stage to which the sample holder 40 is fitted. By driving the stage 42, the sample holder 40 can move in two dimensions or three dimensions. Reference numeral 30 denotes a chip-on cartridge in which a sample is set. Reference numeral 43 denotes an electron beam path through which the transmitted electron beam that has passed through the sample 23 passes.

  S5 shows a state in which the chip-on cartridge 30 is attached to the attachment portion 41. As shown in the figure, the sample 23 is irradiated with the ion beam from the FIB at an angle α with respect to the electron beam optical axis Z in a state where the chip-on cartridge 30 is attached to the attachment portion 41 of the sample holder 40. ing. The operation of the apparatus configured as described above will be described as follows.

  First, the sample 23 is affixed to the mesh 23b to obtain the state shown in S0. The sample 23 is mounted on the mounting portion of the chip-on cartridge 30, and the leaf spring 31 holding the sample 23 is fixed with a fixing screw 33. Thus, the sample 23 is securely fixed to the chip-on cartridge 30.

  Next, the chip-on cartridge 30 is attached to the attachment portion 41 of the sample holder portion 40. Specifically, the chip-on cartridge 30 is fixed to the mounting portion 41 by inserting the chip-on cartridge 30 into the mounting portion 41. In this state, the sample 23 is irradiated with an ion beam from the FIB inclined by the angle α from the optical axis Z, the sample 23 is etched, and the thin film is processed to form a thin film as shown in FIG. The thin film is a film obtained by further etching the thin film portion 23a.

  The thin film is irradiated with an electron beam from the STEM to transmit the thin film. The transmitted electrons are detected by a transmission electron detector (not shown), and image processing is performed. The transmission image of the sample subjected to image processing is displayed on a display device (not shown), and an STEM image can be obtained. An image when the sample surface is etched with the FIB can also be detected by the secondary electron detector 22 (see FIG. 1) disposed in the vicinity of the sample and displayed on the display device.

  As described above, according to the present invention, since the sample attached to the sample holder 40 with the FIB etched can be seen as it is as a transmission image, it is possible to avoid the trouble of attaching the sample and drop the sample. It is possible to provide a sample holder and a multi-beam system that are not damaged.

  As described above in detail, according to the present invention, in a multi-beam system, thin film processing and STEM observation can be performed using a pretilt holder without changing the sample, and the practical effect is extremely large.

20 Electron optical system 21 Ion optical system 22 Secondary electron detector 23 Sample 23a Thin film portion 24 Stage 25 STEM detector

Claims (3)

In a multi-beam system equipped with an electron optical system and an ion optical system in the same chamber, when performing thin film processing as a sample for TEM or STEM observation, the transmission electron detector is placed on an extension line through which the electron beam of the electron optical system passes through the sample. A sample holder for use in a multi-beam system having a sample holder portion for arranging a sample so that at least two kinds of secondary electron images and scanning transmission electron images can be observed simultaneously or alternately.
A mesh for fixing a sample processed to a predetermined thickness;
A chip-on cartridge for setting a sample fixed to the mesh;
A sample holder portion to which the chip-on cartridge is attached,
The sample holder, wherein the chip-on cartridge is inclined at a predetermined angle with respect to the sample holder portion.   In a multi-beam system having an electron optical system and an ion optical system in the same chamber, the electron optical system and the ion optical system are fixed to the chamber at a fixed angle α, and the optical axes of the multi-beam system are coincident points. A multi-beam system configured such that the sample holder according to claim 1 is arranged at a coincident point, and ion beam processing and STEM image observation are performed on the arranged sample.   The multi-beam system according to claim 2, wherein the transmission electron detector is disposed on an extension line of an electron beam optical axis through a stage.

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