JPH02151749A - Analysis of very small part - Google Patents

Abstract

PURPOSE:To continue analysis while the shift of an analytical position is confirmed to be corrected and to analyze the very small part on the surface of a sample with high accuracy by setting a place to be analyzed and the projection of at least one place formed in the vicinity thereof to marks. CONSTITUTION:The microscopic image in the vicinity of a desired place 2 to be analyzed is observed before analysis and the relative positional relation between the place 2 to be analyzed and a mark 4 is recorded. Next, analysis is started and temporarily interrupted on the way to observe a microscope and it is judged whether the positional shift of the place to be analyzed is generated by comparing the relative positional relation between the projections at three points displayed on an image and an actual analytical position with that before analysis. By this method, when shift is generated in the relative positional relation between a sample and a charged particle beam during analysis, said shift can be determined. Therefore, by again performing analysis after the shift between the mark 4 and the analytical position is corrected before the shift of the analytical position becomes excessive, a very small part can be performed with good analytical position accuracy.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention is applicable to a scanning Auger electron microscope (SAM), an electron probe microanalyzer (secondary ion mass spectrometer (SIMS) with EPMA), a cathodoluminescence device ( C.L.
), etc., relates to a method of irradiating a sample surface with a charged particle beam, determining a desired analysis location based on the microscopic image observed as a result, and performing elemental analysis of a minute portion of the sample surface.

[Prior art] Conventionally, like a scanning Auger electron microscope (SAM),
In the elemental analysis method of minute parts using a charged particle beam as a probe, before starting the analysis, the charged particle beam is scanned and irradiated near the analysis point, and the secondary electron image is observed to find the desired result. The analysis points had been decided.

In the analysis of minute parts, it is necessary to always analyze the desired analysis point determined at the beginning, but sometimes the relative positional relationship between the charged particle beam and the sample changes, making it difficult to set the analysis position. There was a problem in that the value decreased.

To solve such problems, the conventional method is to temporarily stop the analysis, re-observe the microscope image to confirm the analysis position shift of the analysis point, and then move the sample or move the charged particle beam. After correcting the misalignment of the analysis point, the analysis was restarted.

When adopting this method of correcting the positional deviation of the analysis point, the analysis point is determined by observing the vicinity of the analysis point with a microscope. If the shape, printing, etc. are not near the analysis point, you will not notice if the analysis position is shifted.
Further, even if a shift in the analysis position is noticed, it is very difficult to correct it.

[Problems to be Solved by the Invention] Therefore, an object of the present invention is to scan and irradiate a charged particle beam onto a sample surface and detect the charged particles emitted from the sample surface to obtain a microscopic image of the sample surface. In the method of analyzing minute parts of the sample surface by observing and determining the analysis location, it is easy to grasp the positional shift of the analysis location during the analysis.
Another object of the present invention is to provide a method for easily correcting positional deviations.

[Means for solving the problem] The above problem is solved by scanning and irradiating the sample surface with a focused charged particle beam, detecting the charged particles emitted from the sample surface, and observing a microscopic image of the sample surface obtained. A method for elemental analysis of minute portions on the surface of a sample, in which a desired analysis location is determined using a method, in which a sample with a mark that can be confirmed by a microscope image near the desired analysis location is placed in an apparatus that performs the above method, and the analysis is performed. Observe the previous microscope image and record the relative positional relationship between the mark and the desired analysis site, then start the analysis, temporarily interrupting the analysis midway through, and check the position of the mark and the actual position in the microscope image. By checking the relative positional relationship with the analysis point and comparing it with the relative positional relationship between the mark recorded before analysis and the analysis point, the positional deviation between the desired analysis point and the actual analysis point can be grasped. It is found that the problem can be solved by a method of analyzing a minute part, which comprises analyzing a desired analysis point by restarting the analysis after correcting the relative positional relationship between the sample and the charged particle beam based on the positional deviation. Served.

The mark placed on the sample surface may be anything that can be confirmed by a microscope image (secondary electron image), and may be, for example, a protrusion or hole on the sample surface (the size of the mark may be adjusted depending on the intended analysis). Although it can be selected appropriately, for example, when analyzing the surface of a GaAs substrate, the diameter is generally in the range of 0° 1 μR to 100 μR and the height (or depth) 10 nz to 10 μ.

As a method of attaching a mark that can be observed as a microscopic image to the sample surface, for example, a method of irradiating the sample surface with a focused charged particle beam can be used.

It is also possible to mark by photolithography.

When irradiating a sample surface with a focused charged particle beam, the sample surface is irradiated with, for example, Ga ions, Ar ions, electrons, etc. that are accelerated in a vacuum chamber.

For example, by irradiating a GaΔS sample for 5 minutes using W(Go) at 30kV and 10n in a gas atmosphere, the sample surface is exposed to zero.
．． A cylindrical mark of 5 μm 1 (diameter) Xo and 1 μl can be made.

In addition, when using photolithography, for example, photoresist is applied to the entire surface of the sample, exposed using a photomask so that a 585 μl (hole) pattern is formed near the analysis location, and then developed. People were deposited. After that, remove the resist with acetone and
By forming an Au pattern of 1, a mark can be placed on the sample surface.

The number and position of marks to be placed on the sample surface are not particularly limited, but at least one mark near the desired analysis point is sufficient; however, for example, marks may be placed in three places surrounding the desired analysis point. It is particularly preferable to attach

The relative positional relationship between the mark on the sample surface and the desired analysis location can be ascertained by using an appropriate method, for example, microscopic observation using secondary electron images.

For example, if you want to mark one spot on the sample surface, sl! 1
1. By expressing the mark and the desired analysis point in the microscopic image using X-Y coordinates, or when marking three points on the sample surface, by measuring the distance between the mark and the desired analysis point. The relative positional relationship with the desired analysis location can be grasped.

The samples marked in this way are placed in the various devices described above and analyzed.

Before starting the analysis, the microscope image is observed and the relative positional relationship between the desired analysis location and the six marks placed in its vicinity is recorded, for example, by photography.

Next, the analysis is started, and the analysis is temporarily interrupted during the analysis to observe the microscope image and measure the relative positional relationship between the actual position of the analysis point and the mark 6.

The positional relationship during the analysis is compared with the positional relationship before the analysis, and if a positional deviation has occurred, the positional deviation is corrected and the analysis is restarted.

This positional shift is corrected by moving the sample or correcting the irradiation position of the charged particle beam.

In this way, by repeating at an appropriate frequency the operation of checking the positional deviation during the analysis, correcting the positional deviation, and then restarting the analysis, it is possible to perform analysis with high accuracy of the analysis position.

Next, the present invention will be explained in more detail with reference to the accompanying drawings.

FIG. 1 is a diagram schematically showing a method for marking a sample surface, and FIG. 2 is a diagram showing the configuration of a scanning Auger electron spectrometer, which is an example of an elemental analysis device to which the method of the present invention can be applied. The schematic diagram, FIG. 3, is a photograph of a microscopic image (secondary electron image) showing the metal structure of copper obtained by an Auger electron spectrometer.

FIG. 1 schematically shows a method of enlarging a sample 1 to be analyzed and marking it with a focused ion beam.

Before the sample 1 is analyzed using, for example, an elemental analyzer, protrusions (or holes) are formed as marks 4 at three locations using a focused ion beam 3 in the vicinity of a desired analysis location 2 of the sample. The sample thus marked is placed in an elemental analyzer.

The Auger electron spectrometer shown in FIG. 2 consists of an electron beam source (electron gun) 6, which is a probe for observation and analysis, placed in a vacuum chamber 5, an electromagnetic lens 7 that focuses the electron beam, and an electron beam that focuses the electron beam on the sample. A scanning coil 8 for scanning above, a scanning circuit 9, a secondary electron detector 10 emitted from the sample surface, an Auger electron energy analyzer 11, an Auger electron spectrum display device 12, and a secondary electron image display device. It has a CRT 13 for doing so.

Place the sample 4 marked as described above in a scanning Auger electron microscope, for example, as shown in FIG. 2, and observe the microscopic image (secondary electron image) near the desired analysis point 2 before analysis. Then, record the relative positional relationship between the desired analysis point 2 and the 6 mark 4.

Next, start the analysis, temporarily stop the analysis midway through, observe the microscope image, and check whether the position of the analysis point has shifted or not. The relative positional relationship with the analysis position is compared with the relative positional relationship before analysis. By comparing in this way, if a shift occurs in the relative positional relationship between the sample and the charged particle beam during analysis, it is possible to understand the shift.

Therefore, by correcting the deviation between the mark and the analysis position before it becomes too large during the analysis process, and then performing the analysis again, it is possible to analyze a minute portion with good accuracy in the analysis position.

[Example] Projections were formed at three locations as marks on the surface of a sample (etched high-purity copper) using a focused ion beam as shown in FIG. 1.

When forming this protrusion, W(Co) and gas were introduced into the vacuum chamber at lXIO-'' Torr, and a Ga+ ion beam of 30 kV and 10 nA was irradiated for about 5 minutes.

This sample was introduced into the scanning Auger electron microscope shown in Fig. 2, and the electron beam acceleration voltage was 10 kV and the beam current was 10 nA.
Observed at. A photograph of the microscopic image (secondary electron image) obtained at this time is shown in FIG. The triangular white part is the protrusion.

Point A in the approximate center surrounded by the protrusion in this image is set as the desired analysis point, and during the analysis, the analysis is temporarily interrupted to observe the microscope image and the distance between the mark and the analysis point is determined. The positional relationship was understood and the positional deviation was corrected. By appropriately repeating this correction, it was possible to analyze the desired analysis point A on the sample surface with high accuracy.

[Effects of the Invention] As explained above, according to the present invention, by using at least one protrusion or hole formed in the vicinity of the analysis point as a mark, it is possible to easily check and correct the deviation of the analysis position. Since the analysis can proceed while the analysis is being carried out, it becomes possible to perform elemental analysis of minute portions of the sample surface using a charged particle beam with high precision in the analysis position.

The method of the present invention is useful as a method for inspecting materials such as semiconductor devices, in which the characteristics of minute regions, especially surface regions, largely depend on product characteristics.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing a method of marking a sample surface in order to implement the method of the present invention, and FIG. 2 is a scanning Auger electron spectrometer that is an example of analyzing a minute part. FIG. 3 is a photograph of a secondary electron image taken by an Auger electron spectrometer showing the metal structure of the surface of high-purity copper. DESCRIPTION OF SYMBOLS 1... Sample, 2... Desired analysis location, 3... Ion beam, 4... Mark, 5... Vacuum chamber, 6... Ion beam source, 7... Electromagnetic lens, 8...Scanning coil, 9...
Scanning circuit, 10... Secondary electron detector, 11... Energy analyzer, 12... Auger electronic display device, 13... CRT. 14...Amplifier. Figure 1 Patent Applicant Sumitomo Electric Industries Co., Ltd. Agent Patent Attorney Aoyama Ao Haka I Name Figure 2 O

Claims (1)

[Claims] 1. A focused charged particle beam is irradiated onto the sample surface while scanning, charged particles emitted from the sample surface are detected, and a microscopic image of the sample surface obtained is observed to identify the desired analysis location. A method for elemental analysis of minute parts of a sample surface to determine the Observe and record the relative positional relationship between the mark and the desired analysis point, then start the analysis, temporarily stop the analysis midway through, and check the relative position of the mark and the actual analysis point using the microscope image. By checking the positional relationship and comparing the relative positional relationship between the mark recorded before analysis and the analysis point, the positional deviation between the desired analysis point and the actual analysis point can be grasped, and the sample can be adjusted based on the positional deviation. and a charged particle beam, and then restarting the analysis to analyze a desired analysis location. 2. The analysis method according to claim 1, which is scanning Auger electron spectroscopy, electron probe microanalysis, secondary ion mass spectrometry, or cathodoluminescence. 3. The analysis method according to claim 1 or 2, wherein the mark is a hole or a protrusion on the sample surface formed by a focused charged particle beam. 4. The analysis method according to claim 1 or 2, wherein the marks are holes or protrusions formed on the surface by photolithography.