JP2005222817A - Scanning electron microscope provided with function of x-ray microscope - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a scanning electron microscope with a function of an X-ray microscope capable of easily switching between both functions. <P>SOLUTION: On the observation through the scanning electron microscope, a holder 16 is positioned so that an opening 20 is set on the path of electron beam 4. The electron beam 4 is irradiated and scanned on a sample 12, and an SME image can be obtained by detecting secondary electron or reflected electron generated at the sample 12. On the observation through the X-ray microscope, either one of anodes 18a, 18b, or 18c is positioned on the path of electron beam 4 by shifting the holder 16. An X-ray is generated by the irradiation of electron beam 4 on either one of the anodes 18a, 18b, or 18c, and the X-ray is transmitted through the sample 12 and converted into light at a phosphor 26. The light is detected by a CCD camera 28, and an enlarged image is obtained. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a scanning electron microscope (SEM) that measures the surface state and composition distribution of a sample.

  A scanning electron microscope converges an electron beam from an electron gun and irradiates the sample surface as an electron beam, detects secondary electrons, reflected electrons, X-rays, light, etc. generated from the sample, and irradiates with the electron beam. By scanning the position on the sample surface, the three-dimensional shape of the sample surface is measured, or the composition distribution in the sample surface is measured.

  Even in the scanning electron microscope, there is a demand not only to detect the surface shape and composition distribution of the sample, but also to detect parts or foreign matters existing in the inner layer or the lower layer, to measure the shape, or to inspect the failure location. . There is an X-ray microscope for measuring such an internal structure that cannot be observed from the surface.

The internal structure and defects cannot be observed with a scanning electron microscope, while the surface shape and composition distribution cannot be measured with an X-ray microscope.
Therefore, if an X-ray microscope function is added to the scanning electron microscope, an X-ray generating anode can be arranged on the electron beam path so that the X-ray microscope can be used. However, since the space where the electron beam path exists is kept in a vacuum, in order to place the anode on the electron beam path, the space must first be opened to the atmosphere, then the anode must be mounted, and the vacuum should be evacuated again. This is annoying operation.
An object of the present invention is to add the function of an X-ray microscope to a scanning electron microscope and facilitate switching between both functions.

  The present invention relates to a scanning electron microscope, a switching mechanism capable of detachably mounting an anode for generating X-rays on an electron beam path while maintaining a vacuum state of a space where an electron optical system is present, and a sample The X-ray detector is disposed on the opposite side of the anode with respect to the position of the X-ray, and detects X-rays transmitted through the sample.

  If an anode is mounted on the electron beam path by the switching mechanism, an X-ray microscope is formed, and X-rays transmitted through the sample can be detected by an X-ray detector. Further, when the anode is removed from the electron beam path by the switching mechanism, a scanning electron microscope is formed, and secondary electrons and reflected electrons generated from the sample are detected by an electron detector, and X-rays generated from the sample are converted into energy dispersive X-rays. It can be detected by an X-ray detector such as a line detector (EDX) or a wavelength dispersive X-ray detector (WDX), and an electron beam can be scanned on the sample.

The switching mechanism may include a seal member that can maintain the vacuum state of the space in which the electron optical system exists by an anode mounted on the electron beam path.
The switching mechanism includes a plurality of types of anodes, and the anodes can be switched.
Further, the anode may include an anode formed with an orifice through which the electron beam can be transmitted when mounted on the electron beam path.

  According to the present invention, the anode can be mounted without removing the vacuum state of the space in which the electron optical system exists to the atmosphere, or the anode can be removed from the electron beam path. Switching can be performed easily. For example, what was observed internally with an X-ray microscope can be switched to SEM image observation as it is.

When a switching member is provided with a seal member that maintains the vacuum state of the space in which the electron optical system exists, the sample chamber in which the sample exists can be opened to the atmosphere. It becomes easy to exchange a sample to be observed as an X-ray microscope while maintaining a vacuum state.
If a plurality of types of anodes are provided, the X-ray source can be easily switched.

  In addition, when an anode in which an electron beam can be passed is included as one kind of anode, when the anode is disposed on the electron beam path, the electron beam passes through the orifice. The electron beam path is set so as to irradiate the sample, and the measurement mode for detecting secondary electrons and reflected electrons generated from the sample and the electron beam path so that the electron beam irradiates the anode around the orifice. It becomes possible to switch the measurement mode in which the X-ray microscope observation is performed using the X-rays generated from the anode only by moving the electron beam path, and the switching can be performed in a shorter time.

Hereinafter, the embodiment shown in FIG. 1 will be described in detail.
Reference numeral 2 denotes an electron gun, which irradiates the sample 12 on the sample stage with the electron generated from the filament 3 as an electron beam 4 converged by the condenser lens 6 and the objective lens 8. Reference numeral 10 denotes a scanning coil for scanning the electron beam 4 on the sample 12, and the irradiation position of the electron beam 4 can be freely moved in a plane by controlling the energization of the scanning coil 10. A vacuum evacuation mechanism (not shown) is connected to the case 1 provided with the electron optical system including the condenser lens 6, the scanning coil 10 and the objective lens 8, and electrons are generated from the filament 3 in the case 1. The degree of vacuum can be maintained.

  Although not shown, for observation with a scanning electron microscope, an electron detector for detecting secondary electrons and reflected electrons generated from the sample and an X-ray generated from the sample are detected in the vicinity of the sample 12. X-ray detectors such as EDX (energy dispersive X-ray detector) and WDX (wavelength dispersive X-ray detector) are arranged.

  A switching mechanism 14 is provided between the objective lens 8 and the sample stage so that an anode can be detachably mounted on the path of the electron beam 4. The switching mechanism 14 includes a plurality of anodes in the holder 16 and also includes an opening. On the lower surface of the housing 1 which is provided with an electron optical system including the condenser lens 6, the scanning coil 10 and the objective lens 8 and is kept in a vacuum, the switching mechanism 14 uses the O-ring 22 as a seal member and the inside of the housing 1 together with the anode. It is attached so that it can be sealed.

  In order to detect X-rays 13 transmitted through the sample 12 on the opposite side of the anode with respect to the sample 12 (below the sample 12 in FIG. 1) when the anode is disposed on the path of the electron beam 4, A phosphor 26 for converting 13 into light is disposed, and a CCD element 28 is disposed as a two-dimensional sensor for detecting light from the phosphor 26.

  FIG. 2 is an enlarged view of the switching mechanism 14. Anodes 18a, 18b, and 18c are attached to the openings of the holder 16, respectively. The other opening 20 of the holder 16 is opened without being provided with an anode in order to allow an electron beam to pass therethrough and function as a scanning electron microscope. It is preferable to provide a plurality of anodes of different materials and thickness depending on the type of X-ray used.

  The anodes 18a and 18b are different kinds of metal plates such as aluminum and copper. If these anodes are arranged on the path of the electron beam 4, X-rays 13 can be generated and the function of the X-ray microscope can be achieved. Further, the inside of the housing 1 is sealed in an airtight state by the seal member 22, and the vacuum state in the housing 1 is maintained. FIG. 1 shows this state.

The anode 18c has an orifice in the center, and when the anode 18c is disposed on the path of the electron beam 4, the electron beam 4 can pass through the orifice, and the path of the electron beam 4 is moved to move the anode 18c. X-rays 13 can also be generated, and can function as a scanning electron microscope (low vacuum SEM) and an X-ray microscope.
When the opening 20 is arranged on the electron beam path, it can function as a scanning electron microscope.

In this embodiment, when performing observation with a scanning electron microscope, the holder 16 is positioned so that the opening 20 is on the path of the electron beam 4. The electron beam 4 irradiates the sample 12, scans on the sample 12, and detects secondary electrons and reflected electrons generated from the sample 12, thereby obtaining an SEM image.
Next, when X-ray microscope observation is performed, the holder 16 is moved to position any one of the anodes 18a, 18b, or 18c on the path of the electron beam 4. When the electron beam 4 irradiates the anode 18a, 18b or 18c, X-rays 13 are generated, and the X-rays 13 pass through the sample 12 and are converted into light by the phosphor 26, and the light is detected by the CCD camera 28. As a result, an enlarged image is obtained.

  When the anode 18a or 18b is positioned on the path of the electron beam 4, the inside of the housing 1 is hermetically sealed by the O-ring 22, so that the sample chamber in which the sample 12 exists is opened to the atmosphere and the sample 12 is opened. Can also be replaced.

  When the anode 18c is positioned on the path of the electron beam 4, since the orifice is opened in the anode 18c, the inside of the housing 1 cannot be hermetically sealed. However, if the orifice is sufficiently small, the sample chamber Even if it is opened to the atmosphere, the degree of vacuum in the housing 1 can be maintained at a degree of vacuum (low vacuum) necessary for generating electrons.

  FIG. 3 shows a switching mechanism in another embodiment. A plurality of anodes 18a to 18c are attached to a rod-shaped holder 16a, and the holder 16a is slidably attached to the edge 23 of the opening provided in the lower part of the housing 1 by O-rings 22a and 22b. It has been. By sliding any one of the anodes on the path of the electron beam 4 by sliding the holder 16a, the measurement mode by the X-ray microscope can be set. Further, the measurement mode by the scanning electron microscope can be set by sliding the holder 16a and positioning the part without the anode on the path of the electron beam 4.

  In the present invention, since the functions of both SEM image observation and X-ray microscope observation can be easily switched and executed by a single scanning electron microscope, bio-related measuring devices, semiconductor-related manufacturing monitoring devices, failure locations Suitable for use as an inspection device.

It is sectional drawing which shows one Example schematically. It is a schematic sectional drawing which shows the switching mechanism in the Example. It is a schematic sectional drawing which shows the switching mechanism in another Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Case 2 Electron gun 3 Filament 4 Electron beam 6 Condenser lens 8 Objective lens 12 Sample 13 X-ray 16, 16a Holder 18a, 18b, 18c Anode 20 Opening 22, 22a, 22b O-ring 26 Phosphor 28 CCD element

Claims (4)

Electrons are accelerated and converged to irradiate the sample on the sample stage as an electron beam, and an electron optical system capable of scanning the electron beam on the sample, and secondary electrons or reflected electrons generated from the sample by the electron beam irradiation. In a scanning electron microscope having at least a detector for detecting,
A switching mechanism capable of detachably mounting an anode for generating X-rays on the electron beam path in a state where the space in which the electron optical system exists is maintained, and a position of the anode with respect to the position of the anode A scanning electron microscope comprising an X-ray detector disposed on the opposite side and detecting X-rays transmitted through a sample. The scanning electron microscope according to claim 1, wherein the switching mechanism includes a seal member that can maintain a vacuum state of a space in which the electron optical system exists by an anode mounted on a path of the electron beam. The scanning electron microscope according to claim 1, wherein the switching mechanism includes a plurality of types of anodes, and the anodes can be switched. 4. The scanning electron microscope according to claim 3, wherein the anode includes an orifice formed with an orifice through which an electron beam can be transmitted when mounted on the electron beam path.

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