JPS63224137A - Sample holder for scanning type electron microscope - Google Patents

Abstract

PURPOSE:To fecilitate inspection of an object with a sufficient contrast by insulating a sample from a holder as well as by grounding an electrode together with the holder while disposing the electrode in the vicinity of the surface of the sample, and by applying voltage to the sample so as to generate an electric field on the surface of the sample. CONSTITUTION:A sample 2 is mounted on a sample receiver 5 disposed through an insulation spacer 41, while an electrode 3 is mounted on a holder 1 on the front side of the sample through a thin insulation spacer 42. This electrode 3 has earth electric potential and voltage 7 is applied on the receiver 5 from the outside of vacuum. Because the spacer is thin, a strong electric field, however, can be generated with the application of a weak voltage. Also because electric field does exist in only the electrode surface of the sample 2, there is little electrostatic lens action, and therefore influence on incident electron beams is neglectable. In this manner enough electric field for elimination of patch field can be obtained, and thereby high contrast for enough inspection of an object which could not be obtained with conventional sample holders can be obtained.

Description

[Detailed description of the invention] [Industrial application field] The present invention is applied to a scanning electron microscope (8EM).

In particular, the present invention relates to an improvement in a part of a sample holder suitable for improving the contrast of observed images.

[Conventional technology]

The conventionally used side entry type sample holder is
The basic structure of the holder disclosed in Japanese Patent Publication No. 58-12701 is shown in FIG. 2 in a simplified manner.

This holder is used with a so-called in-lens objective lens in which a sample is placed inside the objective lens. This holder is used to attach a sample 2 to a sample holder 1 and observe it as it is. When such a holder is used to observe a sample in which there is almost no change in the unevenness and only the material has changed, there is a problem in that the image of the change in the material cannot be observed with sufficient contrast.

[Problems to be Solved by the Invention] An object of the present invention is to provide a means for image observation with sufficient contrast even for a sample in which there is almost no change in unevenness and only the material is changed.

[Means for solving the problems] First, the principle for solving the above problems will be explained. In general, 8EM contrast is formed due to irregularities on the sample surface or changes in material. However, since the contrast of the former is much stronger than that of the latter, the morphology of the sample is generally
! I am aware of it. vice versa.

When observing a sample that has almost no irregularities and only the material has changed, there is a problem in that sufficient contrast cannot be obtained and minute changes cannot be observed. This cause is due to the following phenomenon. First, contrast due to differences in materials is caused by differences in the amount of secondary electrons emitted from the sample due to differences in the work functions of the surfaces of the materials. However, an electric field (called a patch field) that cancels out this difference in work function naturally occurs on the sample surface, and the amount of secondary electron emission due to the difference in material no longer differs, and no contrast occurs. By removing this batch field, it is convenient to observe such samples with sufficient contrast. In recent years, it has been discovered that this field can be removed by forcibly applying an appropriate electric field to the sample surface.

The present invention has been developed by paying attention to such points.

[Effect]

As can be seen from FIG. 2, the conventional sample holder cannot apply an electric field to the sample surface to remove the patch field. That is, since the sample holder 1 is at ground potential, the sample 2 is also at ground potential, and members around the holder (for example).

Since the magnetic path of the objective lens is also generally at ground potential, they all have the same potential, making it impossible to generate an electric field on the surface of the sample. This electric field can be generated by applying a voltage to the sample. What we want here is not a voltage but an electric field, so it is important to be able to apply a strong electric field with a small voltage. The reason for this is that since it can be operated at a low voltage, the electrostatic lens effect formed on the sample mounting surface can be ignored, and in-lens products do not cause mixing aberrations due to the superposition of magnetic fields and static electricity, and do not affect resolution. This is because it can be used without being given.

This can be achieved by arranging a ground electrode on the opposite side of the sample and applying a voltage to the sample.

The present invention has been implemented based on this viewpoint.

〔Example〕

Hereinafter, a simple embodiment of the present invention will be explained with reference to FIG. First, since the sample holder l is made of metal, the sample stand 5 was placed via an insulating spacer 41 for insulation from this holder, and the sample 2 was attached to this stand.

Further, the electrode 3 is attached to the holder 1 via a thin insulating spacer 42 on the sample surface side.

Of course, this electrode has a small hole for observing the sample image. This electrode 3 is naturally at ground potential, and the sample stage 5
A stain pressure 7 is applied outside the vacuum, but since the spacer 42 is thin, a strong electric field can be applied with a weak voltage. Furthermore, since the electric field exists only at the extreme surface of sample 2, almost no electrostatic lens effect occurs.

The influence on the incident electron beam can also be ignored.

With this sample holder, 2
An electric field of about 0 ports/■ can be easily achieved, and an electric field sufficient for patch field removal can be obtained. This holder can be used, for example, to
When the bone plane of the 1aAs superlattice structure was examined by mst, a contrast higher than that which could not be obtained with a conventional sample holder was obtained, and it became possible to observe the bone sufficiently.

Although this example was carried out using a side-entry deaf sample holder, it goes without saying that the present invention is not limited to this and can be carried out in any type of sample holder that is commonly used. According to the present invention, patch fields on the sample surface can be easily removed.

This has the effect of emphasizing the contrast due to the material rather than the contrast due to the unevenness.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a basic sectional view of a sample holder showing a simple embodiment of the present invention, and No. 21iA is a basic sectional view of a conventional sample holder. l...sample holder, 2...sample, 3...earth electrode. 41.42... Insulating spacer, 5... Sample stand, 6...
... Insulated pipe, 7... Applied voltage.

Claims (1)

[Claims] 1. In a sample holder for a scanning electron microscope, the sample is insulated from the holder, an electrode is arranged near the surface of the sample and grounded together with the holder, and a voltage is applied to the sample to A specimen holder for a scanning electron microscope characterized by being configured to form an electric field. 2. The sample holder for a scanning electron microscope according to item 1, wherein the sample holder is of a side entry type.