JPH08329876A - Method and device for preparing observation specimen - Google Patents

Abstract

PURPOSE: To prepare a TEM specimen by the electron beam assist etching process by furnishing a gas supply system in the TEM. CONSTITUTION: An electron beam is led out from an electron source 1 and cast onto a specimen 40 upon converging by the first and the second condenser lens 4, 5, while a reactive gas is sent from gas containers 38, 39 onto the specimen through nozzles 30, 31. The electron beam is deflected for scanning, and chemical reactions of the reactive gas with the specimen are induced with the beam energy, and processing is made by a local etching process. After the processing, the reactive gas is exhausted, and observation of the specimen is made by the generated TEM image. An accurate and flaw-free TEM specimen having an optimum thickness can be achieved with a fine electron beam.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for preparing a sample to be observed with a transmission electron microscope, and particularly to irradiating a sample with an electron beam in a reactive gas atmosphere to induce a chemical reaction in the irradiation section. The present invention relates to an observation sample preparation method and an observation sample preparation device by electron beam assisted etching for locally etching.

[0002]

2. Description of the Related Art In recent years, semiconductor devices have become multi-layered and miniaturized, and in order to evaluate the manufacturing process of devices, observation from the cross-sectional direction is performed to measure the size and shape of each layer, the interface state, and further the crystalline state. The demand is high. As an observation method, there is a transmission electron microscope (hereinafter abbreviated as TEM). Conventionally, a sample for TEM has been prepared by cleaving an observation part of a semiconductor device, laminating the device surfaces of two sample pieces, and mechanically polishing or ion-polishing to make a thin film, but the positioning accuracy is low, and a specific portion is It was difficult to observe.

Various methods have been proposed for these. As a first method, a focused ion beam (hereinafter, FI
(Abbreviated as B) There is a method of preparing a TEM sample by a processing device. FIG. 15 is a configuration diagram of a FIB processing apparatus according to a conventional technique. In FIG. 15, 50 is a liquid metal ion source, 51 is an extraction electrode, 53 is a first lens electrode, 5
6 is a deflection electrode, 57 is a second lens electrode, 58 is a secondary electron detector, and 59 is a sample.

Extraction electrode 51 from liquid metal ion source 50
Ion beam is extracted by the first lens electrode 53,
The sample 59 is focused by the second lens electrode 57 and irradiated on the sample 59, and the sample 59 is processed by ion sputtering. The positioning during processing is performed by scanning the sample 59 with an ion beam by the deflection electrode 56 and detecting secondary electrons generated from the sample 59 with the secondary electron detector 58 (hereinafter referred to as SIM). The image is abbreviated).

Apart from this, as a second method, TEM
The ion beam optical system of the FIB processing apparatus is arranged at a right angle to the electron beam optical system of the above, and a sample for TEM is prepared by sputtering with an ion beam, and secondary electrons generated by irradiation of the TEM electron beam are used. Japanese Patent Laid-Open No. 6-23 confirms the processing position, shape, and sectional thickness of a sample with a scanning electron microscope (hereinafter abbreviated as SEM) image and TEM image.
There is a technique described in Japanese Patent No. 1719.

As a third method, the cross section of the sample is irradiated with an electron beam at right angles to the ion beam optical system, and the thickness of the sample is measured from secondary electrons, backscattered electrons, X-rays, and transmitted electrons. There is a technique described in Japanese Patent Application Laid-Open No. 6-231720 for estimating and processing.

Further, as a fourth method, a gas introduction mechanism is provided in the SEM, and the sample is adsorbed with the reaction gas and irradiated with an electron beam to accelerate the chemical reaction, whereby the atoms on the sample surface and the reaction gas are volatilized. There is a method of observing a cross section of a minute region by electron beam excitation dry etching which is removed as a sexual reaction product. Related to this, Japanese Patent Laid-Open No. 4-2
There is a technique described in Japanese Patent No. 73143.

[0008]

Of the above-mentioned conventional techniques,
The sample processing method by the FIB processing apparatus which is the first method will be described in detail with reference to FIG. FIG. 16 is an explanatory diagram of a sample processing method by a conventional FIB processing apparatus. In FIG. 16, 70 is the ion beam diameter, 7
2 is the electron beam diameter, 73 is the observation point of the TEM sample, and 74
Is the thickness of the observation point.

As shown in FIG. 16, the diameter of the ion beam is 7
0 is 30 to 50 nm, and the beam diameter of the electron beam is 72
Is larger than 1 to 3 nm. Further, the thickness 74 of the observation portion 73 of the TEM sample is 100 because the electron is transmitted.
It is necessary to set the thickness to about 200 nm. This thickness corresponds to several times the ion beam diameter 70. Therefore, when the pattern is positioned by the SIM image, the beam diameter is large, so that the positioning accuracy is poor and the resolution is not good.

Further, since the thickness 74 of the processed portion is about several times as large as the beam diameter 70 of the ion beam, skill is required for the work in order to improve the processing accuracy. Further, since the positioning is performed by SIM image, there is a problem that the surface is processed by ion irradiation. Further, the mass of the ion is as large as (1840 × A) times that of the electron, where A is the atomic weight of the ion, so that the sample may be damaged by the ion beam irradiation such as lattice defect.

The second and third methods are TE
An ion beam optical system is arranged in a direction perpendicular to M and SEM, and the sample for TEM is processed by the ion beam. Therefore, the low resolution, the low positioning accuracy, the low processing accuracy, and the sample by the ion beam are used. There is a problem such as damage. Further, the fourth method describes a method of forming a hole in a sample and observing a cross section, but does not mention a method of making and observing a sample for TEM that slices the sample.

The object of the present invention is to solve the above problems of the prior art, and enables fine TEM observation with high precision, low damage, and without processing the portion to be observed. It is an object of the present invention to provide a sample preparation method and apparatus for observing a semiconductor device for TEM which can be performed.

[0013]

In order to achieve the above object, the constitution of the method for preparing an observation sample according to the present invention is such that an electron beam is applied to the sample in a reactive gas atmosphere by positioning by the secondary electron image of the sample. It is characterized in that the sample is thinly processed by performing reactive etching locally at the irradiation part of the electron beam, and the reactive gas is exhausted after the processing, and is observed by a transmission electron microscope. . In the observation sample preparation method described in the preceding paragraph, the sample irradiation surface of the electron beam is used as an observation surface of a transmission electron microscope, the processing state is observed by a transmission electron microscope image, and the sample is processed to have a predetermined thickness. It is a thing. In the observation sample preparation method described in the preceding paragraph, the transmitted electron intensity is measured when the sample is processed. In the observation sample preparation method according to the preceding paragraph, the electron beam is formed by two optical systems whose optical axes are orthogonal to each other, the transmission electron microscope image of the sample is observed by one optical system, and the other optical system is based on the observation. The sample is processed according to.

In order to achieve the above object, the observation sample preparation apparatus according to the present invention has an electron source for generating electrons, a sample holder for mounting a sample, a sample chamber for loading the sample holder, and the electron source. An irradiation lens system for irradiating the sample with an electron beam extracted from the sample, an imaging lens system for forming an image of transmitted electrons from the irradiated sample, and an observation room for observing the formed transmission electron microscope image. A gas supply for supplying a reactive gas to the sample, to a scanning transmission electron microscope including a secondary electron detector for detecting secondary electrons and transmitted electrons from the irradiated sample, and a transmission electron detector, respectively. Means and rotating means for rotating the sample holder are provided, and the processing range of the sample is determined from the respective image data from the detection signals of the secondary electron detector and the transmission electron detector. In which it characterized in that a setting means that.

In order to achieve the above object, another configuration of the observation sample preparation apparatus according to the present invention is an electron source for generating electrons, a sample holder for mounting a sample, a sample chamber for loading the sample holder, and A scanning electron microscope including an irradiation lens system for irradiating the sample with an electron beam extracted from an electron source, and a secondary electron detector for detecting secondary electrons from the irradiated sample is responsive to the sample. A gas supply system for supplying gas, a transmitted electron detector for detecting transmitted electrons from the sample, a rotating means for rotating the sample holder, image data by the detection signal of the secondary electron detector, and the transmitted electrons. Means for setting the processing range of the sample from the detection signal intensity of the detector is provided.

In order to achieve the above object, still another configuration of the observation sample preparation apparatus according to the present invention is an electron source for generating electrons, a sample holder for mounting a sample, a sample chamber for loading the sample, and An irradiation lens system for irradiating the sample with an electron beam from an electron source, an imaging lens system for forming an image of transmitted electrons from the irradiated sample, and an observation room for observing the formed transmission electron microscope image. An electron source arranged perpendicular to the electron optical system of the transmission electron microscope, an irradiation lens system for irradiating the sample with an electron beam from the electron source, and a reactive gas for the sample. A gas supply system for supplying the secondary electron detector, a secondary electron detector for detecting secondary electrons from the sample, and means for setting a processing range of the sample from image data obtained by a detection signal from the secondary electron detector. It is characterized in that the digits.

[0017]

The function of each of the above technical means is as follows.
In the configuration of the observation sample preparation device according to the present invention, in the scanning transmission electron microscope (hereinafter, simply referred to as STEM), as a method of irradiating the electron beam, a TEM mode of expanding the electron beam and irradiating it as parallel light, and an electron beam aperture Although there is a STEM mode in which irradiation is performed while scanning, irradiation is performed in the STEM mode until processing of the sample for TEM observation is completed, so reactive gas is not supplied when the sample is positioned at the TEM observation position. Since the electron beam is scanned on the sample and positioned by the secondary electron image, the electron beam has a beam diameter smaller by one digit than the ion beam.
The positioning accuracy can be increased. Further, with the electron beam, processing such as ion beam sputtering can be prevented.

The TEM observation section sprays and adsorbs the reactive gas onto the sample, scans the electron beam, induces a chemical reaction between the reactive gas and the sample by the energy of the electron beam, and desorbs the reaction product. Processing can be performed by electron beam assisted etching that locally etches. At this time, if the sample is Si-based, F-based gas is used, and if the sample is GaAs-based, Cl-based gas is used.

When the processing portion has a layered structure or a three-dimensional structure made of a plurality of materials, the reactive gas corresponding to each material is mixed to switch the gas species during the processing. , Can be processed. At the time of processing, the beam diameter can be finely narrowed, so that highly accurate processing is possible, and since the electron has a small mass, damage to the sample can be reduced.

TEM observation is performed in TEM mode and STEM.
It is possible depending on the mode, but since it is performed in STEM mode until the processing state is confirmed, observation in STEM mode stops the supply of reactive gas and exhausts it,
The processed sample is rotated, for example, by 90 ° so that the processed cross section is perpendicular to the optical axis of the electron beam, and the electron beam is scanned for STE.
It can be performed by M image. At this time, STE
When a part of the M image is dark, the mass of electrons is smaller than that of ions, so that the sample is less damaged, so that the electron beam can be processed while irradiating the processed cross section at right angles.

The processing is carried out by setting the electron beam to scan only the dark part, scanning the electron beam while supplying gas again while the sample is rotated by 90 °, and observing the STEM image. You can By eliminating the dark portion of the STEM image and stopping the processing, a TEM sample having an optimum desired thickness can be obtained and the STEM image can be observed. By adjusting the lens voltage of the irradiation lens system and the imaging lens system of the TEM to be in the TEM mode, the TEM image of the processed sample can be observed in-situ with the same apparatus as during processing. In another configuration of such an observation sample preparation device, in the scanning electron microscope,
Positioning and processing are performed in the same way as the STEM with the above configuration,
After setting the processing thickness, rotate the sample, for example, 90 degrees to make the processing cross section perpendicular to the optical axis of the electron beam, measure the transmitted electron intensity with the transmitted electron detector, and obtain the transmitted electron intensity that was obtained in advance. And the thickness of the sample can be optimized. In still another configuration of the observation sample preparation apparatus according to the present invention, the STEM is provided with an electron optical system at a right angle, and the processing is performed by the electron optical system provided at the right angle to confirm the optimum thickness and TEM. Observation can be done with STEM.

[0022]

Embodiments of the present invention will be described below with reference to FIGS.
This will be described below. [Embodiment 1] FIG. 1 shows a TEM according to an embodiment of the present invention.
It is a whole block diagram of the observation sample preparation apparatus for use. As shown in FIG. 1, 1 is a thermionic emission type electron source, 2 is a 6-stage acceleration type acceleration tube, 3 is an optical axis adjusting coil, 4 is a first condenser lens,
5 is a second condenser lens, 6 is a scanning coil, 7 is an objective lens, 8 is a first intermediate lens, 9 is a second intermediate lens, 1
0 is the first projection lens, 11 is the second projection lens, 12 is the secondary electron detector, 13 is the sample chamber, 14 is the observation chamber, 15 is the fluorescent plate, 16 is the transmission electron detector, 17 and 18 are monitors, 1
9 is a deflection signal generator, 20 is a microcomputer, 2
1 is an image memory, 22 is an A / D converter, 23 is a sputter ion pump, 24 is a turbo molecular pump, 25 is a rotary pump, 26 is a turbo molecular pump, 27 is a rotary pump, 30, 31 are blowing gas nozzles, 32, 33 is a gas valve, 34 and 35 are gas flow controllers, 36 and 37
Is a gas valve for opening and closing a gas cylinder, 38 and 39 are gas cylinders containing a reactive gas, 40 is a sample, 121 is an image memory, and 122 is an A / D converter.

The sample processing apparatus for TEM includes an electron source 1, an irradiation lens system for irradiating the sample 40 with an electron beam extracted from the electron source, a sample chamber 13 for loading the sample, and an image of electrons from the sample 40. For an STEM equipped with an imaging lens system, an observation chamber 14 for observing the formed TEM image, a secondary electron detector 12 for detecting secondary electrons and transmitted electrons from the sample 40, and a transmitted electron detector 16. , Gas cylinders 38, 39 for supplying a reactive gas to the sample 40, gas cylinders 38, 3
Gas flow rate controller 34, 3 for controlling the gas flow rate from 9
5. Gas nozzles 30, 31 for blowing gas onto the sample 40
A gas supply system consisting of a secondary electron detector 12, an image memory 121 for storing detection signals from the transmission electron detector 16 as a video signal, a microcomputer 20 for setting a processing range, and a deflection signal for scanning the processing range. It is provided with a scanning range instructing section which is composed of a deflection signal generator 19 for generation.

As shown in FIG. 1, the electron beam optical system includes
A thermionic emission type electron source 1 made of LaB _6, an accelerating tube 2 of a six-stage acceleration method for accelerating the electrons emitted from the electron source 1 to 200 keV and forming a beam, and the accelerated electron beam An optical axis adjusting coil 3 for adjusting the optical axis,
The accelerated electron beam is projected on the sample 40 to about 0.1 μm to 1 μm in the TEM mode, and several n in the STEM mode.
a first condenser lens 4 which converges and irradiates about m
A second condenser lens 5 that converges the converged electron beam in two stages, and an objective lens 7 that forms an image of the transmitted electron.
And a four-stage imaging lens system including a first intermediate lens 8, a second intermediate lens 9, a first projection lens 10, and a second projection lens 11 that sequentially magnify the formed image and project it on the fluorescent plate 15. And an observation chamber 14 for observing the image of the fluorescent plate 15.

In the STEM mode, the scanning coil 6 for scanning the electron beam on the sample 40, the secondary electron detector 12 for detecting secondary electrons generated from the sample 40 when scanning, and the sample 40 are provided. And a transmitted electron detector 16 for detecting transmitted transmitted electrons. In the above configuration, the accelerating tube 2, the optical axis adjusting coil 3, the first condenser lens 4, the second condenser lens 5, etc. are used as an irradiation lens system,
Objective lens 7, first intermediate lens 8, second intermediate lens 9,
The first projection lens 10, the second projection lens 11, etc. are referred to as an imaging lens system.

Since the gas supply system of the sample processing apparatus processes the sample 40 by electron beam assisted etching,
It is configured to supply the reactive gas to the surface of the sample 40. The gas supply system is composed of two systems, and gas cylinders 38 and 39 for storing a reactive gas, respectively, and a gas valve 3 for opening and closing the gas cylinders 38 and 39, respectively.
6, 37, gas flow rate controllers 34 and 35 for adjusting the reactive gas flow rates, gas valves 32 and 33 for opening and closing the reactive gas flow paths, and the reactive gas sprayed on the surface of the sample 40, respectively. Gas nozzle 30,
It consists of 31.

In order to maintain a high vacuum in the electron beam optical system, the electron source 1 and the irradiation lens system are operated by the sputter ion pump 23, the sample chamber 13 by the turbo molecular pump 24 and the rotary pump 25, and the observation chamber 14 by the turbo molecular pump. The pump 26 and the rotary pump 27 are configured to perform differential pumping independently. Further, diaphragms are respectively provided between the sample chamber 13 and the irradiation lens system and the imaging lens system to prevent the reactive gas from flowing into the electron beam optical system.

Next, the control system for setting the region of the sample 40 to be processed will be described. First, the secondary electron image system includes a secondary electron detector 12 for detecting secondary electrons, an A / D converter 122 for A / D converting the detection signal, and an image memory for storing the converted digital signal. And 121. Similarly, the transmission electron image system includes a transmission electron detector 16 for detecting transmission electrons, an A / D converter 22 for A / D converting the detection signal of the transmission electron detector 16, and the converted digital signal. It is composed of an image memory 21 for storing.

The microcomputer 20 for setting the processing range is connected to the deflection signal generator 19, reads the image signal memory from the image memory 121 and the image memory 21, and causes the deflection signal generator 19 to generate a deflection signal. In addition, the monitor 1 is connected to monitors 17 and 18, and the image signal memory is used as a secondary electron image and a transmission electron image in the monitor 1 respectively.
7 and 18 are displayed.

Next, the operation of the TEM observation sample preparation apparatus according to the embodiment of FIG. 1 will be described with reference to FIG.
2 is a sectional view of the sample by the TEM observation sample preparation device of FIG. 1, FIG. 3 is a perspective view of the sample shown in FIG. 2, and FIG. 4 is a perspective view of a sample holder of the sample shown in FIG. The sample for TEM observation shown in FIG. 2 includes GaAs layers 92a, 92b, 9 on a GaAs substrate 90 by molecular beam epitaxy.
2c and AlGaAs layers 91a, 91b, 91c, 91d
Is an element of a one-dimensional superlattice structure in which and are grown alternately,
The numbers on the left side of the drawing are examples of the thickness of each layer. It should be noted that the numbers shown in the description of the present specification are similarly examples.

The sample preparation will be described with reference to FIG. In FIG. 3, 40 is a sample, 41 is an observation part, 42 is a protrusion, and 49 is an electron beam irradiation direction. The numbers shown are for example only. As shown in FIG. 3, the sample 40 was separated from the device by a width of 500 μm and a length of 2 m.
The width is 30 μm by machining on the surface.
Protrusions 42 having a height of 70 μm are provided. Further, the broken line portion is processed by electron beam assisted etching in the center of the protrusion 42, and the thickness of the observation portion 41 is processed to 100 nm or less so that the electron beam can be transmitted, and the observation sample 40 is prepared. . At the time of TEM observation of the sample 40, the electrons are emitted from the direction of the electron beam irradiation direction 49 shown in the figure.

Next, attachment of the sample to the sample holder will be described with reference to FIG. In FIG. 4, 43 is a sample holder. x, y, z are left and right (left and right with respect to the drawing),
A front-back direction (perpendicular to the drawing), a vertical direction (up-down direction with respect to the drawing), and θ are rotation directions around the y-axis. Sample 40
To the side-entry type sample holder 43,
Attach so that 2 is on top. The longitudinal direction of the protrusion 42 is made to coincide with the longitudinal direction of the sample holder 43.

Unlike the conventional TEM observation sample holder, the sample holder 43 does not have a hole for electron transmission at the bottom and has a small width so that it can rotate by θ = ± 90 °. Further, the sample holder 43 is mounted on the sample chamber 13 in the x-axis, as in the TEM in the prior art.
The mechanism is such that the y axis can be finely moved by ± 1 mm and the z axis can be moved by about 0.3 mm. The mounting of the sample 40 on the sample holder 43 is similar to the conventional method performed by a normal SEM.

Next, the procedure for loading the sample holder into the sample chamber 13 and observing the sample will be described with reference to FIGS. Figure 5
1 is an explanatory view of loading a sample holder on the TEM sample processing apparatus of FIG. 1, and FIG. 6 is a schematic explanatory view of a sample, an SEM image, and a STEM image of each processing step by the TEM sample processing apparatus of FIG. As shown in FIG. 5, the sample holder 43 is attached to the objective lens 7
It is loaded inside the sample chamber 13 such that the reaction gas is sprayed from above by the spray nozzles 30 and 31. This uses a so-called in-lens system in which a sample is placed in an objective lens in order to realize high resolution.

Next, with reference to FIG. 1, focusing on FIG. 6, the processing procedure and the observation procedure of the sample 40 will be described. FIG. 6 shows NO. Shows the order from Step 1 to Step 6, each figure in the left column shows a sample processing method in each step in the leftmost column, each figure in the middle column shows an SEM image in each step in the leftmost column, each in the right column The figure shows STEM images in each step in the leftmost column.
Steps 1 to 5 are in STEM mode, step 6 is T
Observation and processing are performed in the EM mode. 6, in the figure, 91a, 91b, 91c, 91d, 92a,
Reference numerals 92b and 92c denote the same parts as those in FIG.
Since 0, 41, and 43 are the same parts as those in FIG. Only new codes will be described. Four
4 is an electron beam, 45 is a reactive gas, 48 is a processing area,
100 is a dark part, 110, 111, 112, 113, 11
5 is an SEM image at each stage, and 114 and 116 are STEM images at each stage.

First, in step 1, the region to be processed is positioned. The electrons emitted from the electron source 1 are transferred to the acceleration tube 2
It is accelerated to 00 keV, and the first condenser lens 4 and the second condenser lens 5 finely squeeze the electron beam 44 so that the beam diameter becomes 2-3 nm, and the scanning coil 6 scans the sample 40. At this time, secondary electrons generated from the sample 40 are detected by the secondary electron detector 12, and the detection signal is converted into a digital signal by the A / D converter 122,
It is stored in the image memory 121.

Next, the image data in the image memory 121 is converted by the microcomputer 20 into the SEM image 11 in step 1.
It is displayed as 0 on the monitor 17. The processing area 48 is set in the microcomputer 20 on the SEM image 110. This allows the electron beam 44 to automatically scan only the processing area 48 during processing. Since the positioning is performed by the fine electron beam as described above, it is highly accurate and is not processed by sputtering unlike the ion beam.

Next, in step 2, the processing area 48 is processed. For processing, the reactive gas 45 is blown onto the sample 40, the electron beam 44 is irradiated, the reactive gas 45 adsorbed on the surface of the sample 4 is decomposed, and only the irradiation portion of the electron beam 44 is locally etched. As the reactive gas 45, Cl ₂ gas such as Cl ₂ , SiCl ₄ , CCl ₄ or the like is used because the material of the sample 4 is GaAs, but Cl ₂ gas is used in this embodiment. However, the Cl ₂ gas is Ga
Etching occurs spontaneously without irradiating the electron beam 44 on As.

Here, the description of each step in FIG. 6 will be temporarily suspended, and a method for coping with the above spontaneous etching will be described. As one method, there is a means for setting the thickness of the observation portion 41 to be thick in advance in consideration of the amount of processing by spontaneous etching so that the thickness becomes optimum at the end of processing. The processing amount by the spontaneous etching depends on the gas pressure of the reactive gas 45 and is proportional to the processing time. Therefore, the amount to be processed by spontaneous etching is predicted in advance, and the amount to be processed by electron beam assisted etching is set to be small in consideration of the amount to finally obtain the target thickness.

In addition to this, as another method, it is possible to suppress spontaneous etching by lowering the temperature of the sample 40 when processing by electron beam assisted etching. Furthermore, as another method, there is a method in which a gas that suppresses spontaneous etching is mixed with the reactive gas 45 and etching is performed. For example, SiCl ₄ and CCl ₄ are used as a mixed gas, and a reactive gas Cl ₂ is used.
Spontaneous etching can be suppressed by setting the mixing ratio of and to an appropriate value.

When the ratio of the reactive gas Cl ₂ is large,
The spontaneous etching of the observation portion 41 corresponding to the side wall of the processed portion is large, and when the proportion of SiCl ₄ gas or CCl ₄ gas is large, the spontaneous etching is small but the overall processing speed is small. Here, SiCl ₄ is used as the mixed gas.
Cl ₂ gas in the gas cylinder 38 and S in the gas cylinder 39
The iCl ₄ gas is stored, the valves 36 and 37 are opened, the gas flow rates and the mixing ratio of the two gases are adjusted by the flow rate controllers 34 and 35, the valves 32 and 33 are opened, and the nozzles 30 and 3 are opened.
Cl ₂ and SiCl ₄ gas are sprayed onto the sample 40 as a reactive gas 45 via 1 to be adsorbed. The processing area 48 is set in the deflection signal generator 19 by the microcomputer 20, and the electron beam 44 automatically scans and irradiates the processing area 48.

The reactive gas 45 is decomposed by the energy of the electron beam 44 and reacts with the sample 40 to progress the etching. At this time, the observation section 4 corresponding to the side wall of the processing section
It is considered that a Si thin film is formed by the mixed gas SiCl ₄ in 1 to prevent spontaneous etching by Cl ₂ gas. Since the thin film of the formed Si is very thin, even if it remains, it does not affect the TEM observation. Further, in the subsequent step 5, the Si thin film can be removed at the stage of processing by irradiating the observation section 41 with an electron beam at a right angle. From the SEM image 111 shown in step 2, the state of the processing region 48 being processed can be monitored.

Again, the processing of the processing area 48 in step 2 will be described with reference to FIG. When the processing region 48 is processed, the processing is performed in two steps in order to reduce the processing time and finish the observation part 41 with high accuracy. FIG. 7 is an enlarged explanatory diagram of the processing method of the processing step 2 of FIG. In FIG. 7, the left figure shows the roughing method, and the right figure shows the finishing method. In the figure, the same reference numerals as those in FIG. Only new codes will be described. Reference numeral 48a is a rough processing area in the processing area 48, and 48b is a finish processing area in the processing area 48.

In the first stage rough machining shown in the left diagram of FIG.
The diameter of the electron beam 44 is set to about 0.5 μm by the first condenser lens 4 and the second condenser lens 5,
The electron beam current is increased to scan the rough processing area 48a, and high-speed processing is performed while leaving 1 μm around the observation portion 41. Next, in the second stage finishing process shown on the right side of FIG. 7, the acceleration voltage is set to 100 keV and the electron beam diameter is set to 2 by the first condenser lens 4 and the second condenser lens 5.
The observation part 41 is obtained by finely narrowing down to about 3 nm and scanning the finishing region 48b.

After the roughing shown in the left diagram of FIG. 7 is finished, the SEM image is used to observe the result of the machining and the second stage finishing process shown in the right diagram of FIG. The processed part may be observed. The observation and processing method of the SEM image of the sample unprocessed portion will be described with reference to FIG.
FIG. 8 is a schematic explanatory view of a sample unprocessed portion observed by a SEM image, a processing method, and a sample cross-sectional view. In FIG. 8, the left figure shows the observed image, the middle figure shows the processing method 1, the right figure shows the processing method 2, and the upper row shows S in observation, processing method 1, and processing method 2.
The EM image and the lower part show cross sections in observation, processing method 1 and processing method 2. In the figure, the same reference numerals as those in FIG. Only new codes will be described. Reference numeral 46 is an unprocessed region, 47 is a hatched portion for irradiating an electron beam, 117, 118, and 119 are SEM images.

As shown in the SEM image and cross section in the left diagram of FIG. 8, an unprocessed region 46 may be observed in the SEM image 117. The cause of the unprocessed area 46 is as follows.
This may be due to the inclination of the sample during processing or the spread of the tail of the electron beam. On the other hand, as shown in the middle diagram of FIG. 8, the processing method 1 in which the beam diameter of the electron beam 44 is narrowed down similarly to the finishing process, and the processing time is shortened as shown in the right diagram of FIG. Processing method 2 in which the sample 40 is inclined and processed with a thick electron beam diameter during rough processing
There is.

In the processing method 1 shown in the middle diagram of FIG. 8, the SEM image 118 is obtained by narrowing the electron beam 44 to about 2 to 3 nm.
Therefore, the unprocessed region 46 can be processed by scanning only the shaded portion 47. In the processing method 2 shown in the right diagram of FIG. 8, since the tilt angle of the unprocessed material region 46 can be known from the size of the unprocessed region 46 of the SEM image 117, the sample 40 is tilted to the same extent as that and the thick electron beam is used. Diameter unprocessed area 4
6 can be processed at high speed.

Although not shown in the drawing, the structure of the sample holder 43 is set to a mechanism capable of rotating the sample mounting position only in the θ direction and biaxially with 90 ° in the same manner as the conventional TEM holder. It is also possible to obtain a SEM image in the direction perpendicular to the surface of the observation section 40 and perform more accurate processing.

Again, each step will be described with reference to FIG.
After the finishing process is completed, the SEM image 112 is observed in order to confirm the processing state in step 3 of FIG. For the observation, the electron beam 44 was once stopped, the supply of the reactive gas 45 was stopped, and when the exhaust of the reactive gas 45 was completed, the electron beam 44 was generated and the accelerating voltage 100 ke
V, electron beam diameter 2-3 nm. When the processing state is observed and the processing is incomplete, the process returns to step 2 and the reactive gas can be supplied again to perform the processing.

Next, in step 4, TEM observation is performed in the STEM mode. The fluorescent plate 15 is raised, the sample holder 43 in FIG. 4 is rotated by θ = 90 °, and further finely moved along the x axis and the y axis to align the observation section 41 with the optical axis of the electron beam optical system. Accelerating voltage of 200 keV, beam diameter 2-3 nm
The reactive gas 45 is not supplied by the fine electron beam of, and the sample 40 is scanned. Secondary electrons generated from the sample 40 are detected by the secondary electron detector 12, and electrons transmitted through the sample 40 are detected by the transmission electron detector 16.

The detection signal of the secondary electron detector 12 and the detection signal of the transmission electron detector 16 are respectively the A / D converter 1
It is converted into a digital signal by 22 and 22 and stored in the image memories 121 and 21 in synchronization with the electron beam scanning. The microcomputer 20 displays the image data on the monitors 17 and 18 as SEM images and STEM images.

The SEM image 113 thus obtained,
The STEM image 114 displays the same portion of the observation unit 41. In the SEM image 113 and the STEM image 114, the AlGaAs layers 91d, 91c,
It is observed that 91b, 91a and GaAs layers 92c, 92b, 92a are alternately layered. The SEM image 113 is observed with a uniform contrast over the entire visual field, but the STEM image 114 has a bright portion and a dark portion partially in the image due to the uneven thickness of the observation portion. For example, S in the figure
In the TEM image 114, the dark portion 100 is the sample 4
It is considered that this occurred because the thickness of 0 was large and it was difficult for electrons to pass through. At this time, the area surrounding the dark portion 100 is set as a rework area by the microcomputer 20.

Next, in step 5, the reprocessed region is processed. Since ions are used in conventional FIB processing,
Its mass is larger than that of electrons, and there is a risk that the sample will be damaged if the observation surface is irradiated with an ion beam at a right angle. In the case of electrons, since the mass is small, the possibility of damage is low, and the observation surface is processed by irradiating it with an electron beam at a right angle.

The scanning range of the rework area is set in the deflection signal generator 19 by the microcomputer 20, and the valve 3
2 and 33 are opened and a reactive gas 45 is supplied, and the electron beam 44 is processed with the same accelerating voltage and beam diameter as in the STEM observation of the above step 4. SEM image, S at the same time as processing
The TEM image is observed, and the processing is performed until the STEM image 116 is clearly detected.

In step 4, the STEM image observation section 41 is used.
If the whole is dark and the entire observation portion 41 is not yet electron-transmissive in thickness, it is possible to return to step 2 for reprocessing without proceeding to the next step 5. Since the lattice image cannot be observed in the STEM image, the TEM image is observed in step 6. For observing the TEM image, the fluorescent plate 15 is lowered, the electron beam is spread over the entire observation area by the condenser lens 1 and the condenser lens 2, and the observation section 41 is irradiated with a parallel beam, and the electron transmitted through the sample 40 is irradiated by the objective lens 7. The first intermediate lens 8, the second intermediate lens 9, the first projection lens 10, the second projection lens 1
The image is sequentially enlarged at 1 and projected on the fluorescent screen 15 and observed in the observation room 14. As a result, the sample 40 can be observed on the spot without moving and attaching it to another device.

[Embodiment 2] Next, another embodiment of the present invention will be described with reference to FIG. FIG. 9 is a schematic explanatory view of a sample, an SEM image, and a STEM image in each processing step of the sample manufacturing method according to another embodiment of the present invention. In FIG. 9, No. in the leftmost column. Shows each step, each figure in the left column shows the sample in each step, the figure in the middle column shows the SEM image, and the figure in the right column shows the STEM image. In the figure, the same reference numerals as those in FIG. 6 are the same parts, and therefore the repetitive description will be omitted and only new reference numerals will be described. 12
3 is an SEM image, 124 is a STEM image, and 125 is a dark part.

Steps 4 ', 5', and 6'shown in [Example 2] of FIG. 9 are steps 4 described in [Example 1] of FIG. 6, and the entire observation portion 41 of the STEM image is dark. If the observation portion 41 is not thick enough to transmit electrons, the reprocessing is performed in the TEM mode.

In step 4 ', when the entire STEM image 124 is the dark portion 125, the sample 40 is irradiated with the electron beam 44 while being rotated by 90 ° as shown in step 5'in the middle diagram of FIG. The condenser lenses 4 and 5 are spread over the entire observation region and are collectively irradiated as a parallel beam. At the same time, the reactive gas 45 is supplied to etch the entire observation part 41.

When the observation portion 41 has a thickness that allows electron transmission through such processing, the objective lens 7, the intermediate lens 8,
9. TE on the fluorescent plate 15 by the projection lenses 10 and 11
It can be seen that the M image is formed and the observing section 41 is in a state where TEM observation is possible. Therefore, the supply of the reactive gas 45 is stopped and the residual gas is exhausted.

Next, in step 6'shown in FIG. 9, the TEM is used while the irradiation state of the electron beam at the time of processing in step 5'is maintained.
Observations can be made. Further, when the positioning of the TEM observation position of the sample 40 does not require so much accuracy, the processing in the TEM mode can be performed from the step 2 shown in FIG. In that case, 90 from the sample 2 in step 2 of FIG.
In the rotated state, processing and observation can be performed in the TEM mode just described.

[Third Embodiment] Next, still another embodiment of the present invention will be described with reference to FIGS. FIG. 10 is a sectional view of a sample in a sample preparing method according to another embodiment of the present invention, and FIG. 11 is a reaction gas supply system configuration diagram in a sample preparing method according to still another embodiment of the present invention. In [Example 3], the material of the sample 40 in [Example 1] of FIG. 1 was a GaAs-based compound semiconductor.
The difference is that it is intended for MOS semiconductor devices made of i-based materials. In FIG. 10, 93 is a Si substrate and 94 is a Si substrate.
n + layer, 95 is SiO ₂ , 96 is Al wiring, 97 is phosphor glass (hereinafter referred to as PSG), 98 is SiO ₂ , and 99 is poly-Si gate.

As shown in FIG. 10, the sample 40 is a MOS
Sin + layer 9 on Si substrate 93 at the semiconductor gate
4, SiO ₂ 95, Al wiring 96, poly-Si gate 9
9, SiO ₂ 98, and PSG 97 are sequentially laminated. When this sample 40 is subjected to electron beam assisted etching for TEM observation, the SiO ₂ , Si, and PSG portions can be etched by the F-based reactive gases XeF ₂ , CF ₄ , and SF ₆ , but with respect to Al, Etching does not proceed because the F and F gases have low reactivity. In general,
Al reacts with Cl-based gases Cl ₂ , SiCl ₄ , and BCl ₃ and is etched.

As described above, when Si and Al coexist as materials, for example, there is a method in which the Si-based material is first etched using XeF ₂ gas and the reactive gas is switched when Al is exposed. , It takes time to switch the gas. Further, when each material is layered, it can be dealt with by switching the gas, but it is difficult when each material is three-dimensionally arranged in a complicated manner. Therefore, in such a case, an F-based gas and a Cl-based gas are mixed and used as the reactive gas. The processing speed of each material can be adjusted by the gas mixture ratio. In this example, XeF
₂ and Cl ₂ are used. Therefore, the gas cylinder 38 has Xe.
F ₂ and Cl ₂ are stored in the gas cylinder 39. Then, the flow rate controllers 34 and 35 are adjusted to adjust the gas flow rate, and the mixing ratio of both gases is adjusted to set the processing speeds of different materials to the same level. Then, the etching gas is supplied to the sample 40 through the nozzles 30 and 31.

Next, the gas supply system in this embodiment will be described with reference to FIG. In the figure, the same reference numerals as those in FIG. Only new codes will be described. Reference numeral 101 is a supply pipe, and 102 is a gas nozzle. In [Embodiment 1] of FIG. 1, two kinds of gas were separately supplied onto the sample 40 by the nozzles 30 and 31, respectively, but in the present embodiment, gas valves 32 and 33 are provided as shown in FIG. It is connected to one supply pipe 101, mixed by the supply pipe 101, and supplied to the sample by the gas nozzle 102.

[Embodiment 4] Next, still another embodiment of the present invention will be described with reference to FIG. FIG. 12 is a configuration diagram of an observation sample preparation device according to still another embodiment of the present invention. In this embodiment, an SEM is used instead of the TEM of [Embodiment 1] in FIG. In FIG.
130 is an electron source, 131 is a condenser lens, 132 is a scanning coil, 133 is an objective lens, 134 and 135 are gas nozzles, 136 is a sample holder, 137 is a secondary electron detector, 138 is a transmission electron detector, and 139 is an ion pump. , 140 is a turbo molecular pump, 141 is a rotary pump, 142 is a turbo molecular pump, 143 is a rotary pump, 144, 145 are valves, 146 is an anode, and 147 is a sample chamber.

The electron beam optical system of the observation sample preparation device is
Thermionic emission type electron source 130 made of W, the anode 146 that accelerates the electrons emitted from the electron source 130 to 25 keV, the condenser lens 131 that converges the accelerated electrons, and the converged electron beam The scanning coil 132 for scanning and the converged electron beam are used for the sample 40.
An objective lens 133 that converges and irradiates the sample on top, a secondary electron detector 137 that detects secondary electrons generated from the sample 40 by the irradiated electron beam, and a transmitted electron detector that detects electrons that penetrate the sample 40. And 138.

The gas supply system of the apparatus is as shown in FIG.
In the same manner as in [1], two types of piping systems are used to spray different types of reactive gases onto the surface of the sample 40 via the gas nozzles 134 and 135 by opening and closing the valves 144 and 145. In order to maintain a high vacuum in the electron beam optical system, the electron source 130 is an ion pump 139, the condenser lens 131, the objective lens 133 is a turbo molecular pump 140 and a rotary pump 141, and the sample chamber 147 is a turbo molecular pump 142 and a rotary pump 141. Pump 14
Differentially exhausts independently by 3.

Further, a portion for obtaining a secondary electron image and a transmission electron image from the detection signals of the secondary electron detector 137 and the transmission electron detector 138 respectively, setting a processing range, and outputting a deflection signal to the scanning coil 132, The structure is similar to that of [Example 1] in FIG. Further, the sample holder 136 is an ordinary S
Same as EM, but with a structure that can rotate ± 90 °.

Next, the operation of the observation sample preparation device will be described. Sample holder 136 with the surface of sample 40 facing up
And the sample holder 136 is loaded into the sample chamber 147.
In the present embodiment, the processing is different in the positioning of the step 1, the processing of the step 2, the observation of the processing state of the step 3 and the step 4 and subsequent steps in [Example 1] shown in FIG. However, the electron beam diameter is 7
Since it is as large as -10 nm, the processing accuracy becomes a little worse.

Next, processing corresponding to step 4 in FIG. 6 is performed. Observation is performed by rotating the sample holder 136 by 90 °. In this case, with SEM, the acceleration voltage is 25 ke
Since it is as small as V, even if the thickness of the observation section 41 is thinned to about 100 nm, the electrons are largely scattered in the sample 40, and the scattered electrons escaped from the observation section 41 are detected by the transmission electron detector 138. Even if a transmission electron image is formed from a detection signal, the resolution is poor and it is difficult to detect it as a transmission electron image.

However, the brightness of the image corresponds to the intensity of the transmitted electrons, and the brightness of the image changes according to the thickness of the observation section 41. If you ask for the relationship, TEM from the brightness of the image
Processing of the optimum thickness for observation is possible. If the brightness of the image is dark, return to step 2 in FIG. 6, or process the sample 40 while rotating it by 90 ° as in step 5, and stop the processing when the transmitted electron image becomes bright. Is also possible. In this embodiment, it is necessary to transfer the sample 40 to another TEM at the time of TEM observation, but as compared with the ion beam processing, the processing accuracy is high, there is no damage, and the thickness of the observation portion 41 is monitored by transmission electrons. Since it can be done, it has advantages such as being the optimum thickness.

[Fifth Embodiment] Next, still another embodiment of the present invention will be described with reference to FIGS. In this embodiment, the sample is processed by electron beam assisted etching by SEM, and the TEM observation of the sample is performed in the same chamber.
The two optical systems are arranged at right angles so that they can be performed by EM. FIG. 13 is a block diagram of an observation sample preparation device according to still another embodiment of the present invention, and FIG.
It is a schematic explanatory drawing of the sample processing method in the observation sample preparation apparatus of the Example of FIG.

The observation sample preparation device according to the present embodiment has a TEM optical system as shown in FIG. 1 [Example 1], an SEM optical system as shown in FIG. 12 [Example 4], and a gas supply system as shown in FIG. 11
[Embodiment 3] of the above. Therefore,
In the figure, the same reference numerals as those in FIGS. 1, 11, and 12 denote the same parts. However, when performing TEM observation with the TEM optical system,
The STEM mode in which the electron beam is scanned to detect the transmitted electrons is not used, but the TEM mode in which the electron beam is irradiated in parallel to the entire observation region to obtain a transmitted electron image is used. The gas supply system may be either a method of supplying different kinds of gas from separate nozzles or a method of supplying mixed gas from one nozzle, but the latter configuration is used in this embodiment.

Next, the preparation of the observation sample will be described. The sample 40 is loaded with the sample holder 43 so that the sample surface is perpendicular to the optical axis direction of the SEM optical system. Processing is SE
By the M optical system, it is possible to perform the positioning in the step 1, the processing in the step 2 and the observation in the processed state in the step 3 shown in FIG. 6 in the same manner as in [Example 4].

Next, in the portion corresponding to the STEM observation in step 4 shown in FIG. 6, the sample holder 43 is not rotated, and the TEM optical system is used to observe the position at that position. At this time, TEM observation is possible if the processing is performed accurately. However, when a part of the TEM image is dark and cannot be observed, the area is set in the microcomputer 20 as a rework area.

Next, FIG. 14A shows a processing method when a part of the TEM image is dark. In this case, reworking corresponding to step 5 in FIG. 6 is performed. The rework is S
It is performed from the surface direction of the sample 40 by the electron beam of the EM optical system. Therefore, the electron beam of the TEM optical system stops. This reprocessing is performed by scanning the region set in the microcomputer 20 with the electron beam 44 of the SEM while supplying the reactive gas 45. When the processing is completed, the supply of the reactive gas 45 is stopped and the electron beam 44
Is switched to the TEM optical system for TEM observation.

Next, in step 4 of FIG. 6, when the entire TEM image is dark and the image cannot be observed, it is possible to process it by the electron beam of the TEM optical system. 14
The processing method in this case is shown in (b). The electron beam 44 of the TEM optical system is irradiated under the same conditions as during observation,
Reactive gas 45 is supplied for processing. During processing, the TEM image is observed, and the gas supply is stopped when the TEM image becomes detectable. Even after the gas supply is stopped, the TEM image can be continuously observed. In this embodiment, two electron optical systems must be provided, which complicates the device configuration.
Since it is not necessary to rotate the sample 40, operability is excellent.

[0078]

As described above in detail, according to the configuration of the present invention, it is possible to perform fine TEM observation with high accuracy, low damage, and without processing a portion to be observed, for example, a semiconductor. A sample preparation method and apparatus for TEM observation of a device can be provided. More specifically, in order to prepare a sample for TEM observation, positioning is performed by a secondary electron image. Therefore, it is possible to perform highly accurate positioning by using a fine electron beam, and to perform sputtering like ions. Has the effect of preventing processing due to Observation sample processing is performed by irradiating a sample with a finely focused electron beam in a reactive gas atmosphere and locally performing reactive etching at the irradiation portion of the electron beam, because electrons have a smaller mass than ions, It has a high-precision and little damage processing effect. In addition, after processing the observation sample,
By exhausting the reactive gas, there is an effect that a transmission electron microscope image can be observed in the same device. Also, when irradiating a sample with an electron beam in a reaction gas atmosphere, the irradiation surface of the electron beam is used as the observation surface of a transmission electron microscope image to observe the processing state at the same time as processing the sample and to detect the transmitted electron intensity. Reworking the unprocessed part has the effect of processing the sample to an optimum thickness.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an observation sample preparation device for TEM according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a sample by the observation sample preparation device for TEM of FIG.

FIG. 3 is a perspective view of the sample shown in FIG.

FIG. 4 is a perspective view of a sample holder for the sample shown in FIG.

5 is an explanatory view of loading a sample holder on the observation sample preparation device for TEM of FIG. 1. FIG.

FIG. 6 is a schematic explanatory view of a sample, an SEM image, and a STEM image of each processing step by the observation sample preparation device for TEM of FIG.

FIG. 7 is an enlarged explanatory view of a processing method of processing step 2 of FIG.

FIG. 8 is a schematic explanatory view of a sample unprocessed portion observed by an SEM image, a processing method, and a sample cross-sectional view.

FIG. 9 is a schematic explanatory view of a sample, an SEM image, and a STEM image in each processing step of the sample manufacturing method according to another embodiment of the present invention.

FIG. 10 is a sectional view of a sample in a sample manufacturing method according to another embodiment of the present invention.

FIG. 11 is a configuration diagram of a reaction gas supply system in a sample preparation method according to still another embodiment of the present invention.

FIG. 12 is a configuration diagram of an observation sample preparation device according to still another embodiment of the present invention.

FIG. 13 is a configuration diagram of an observation sample preparation device according to still another embodiment of the present invention.

FIG. 14 is a schematic explanatory view of a sample processing method in the observation sample preparation device of FIG.

FIG. 15 is a configuration diagram of a FIB device according to a conventional technique.

FIG. 16 is an explanatory diagram of a sample processing method by a FIB device in the related art.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electron source, 2 ... Acceleration tube, 3 ... Optical axis adjustment coil, 4 ... First condenser lens, 5 ... Second condenser lens, 6 ...
Scanning coil, 7 ... Objective lens, 8 ... First intermediate lens, 9
... second intermediate lens, 10 ... first projection lens, 11 ... second projection lens, 12 ... secondary electron detector, 13 ... sample chamber, 1
4 ... Observation room, 15 ... Fluorescent plate, 16 ... Transmission electron detector, 1
7, 18 ... Monitor, 19 ... Deflection signal generator, 20 ... Microcomputer, 21 ... Image memory, 22 ... A / D converter, 23 ... Sputter ion pump, 24 ... Turbo molecular pump, 25 ... Rotary pump, 26 ... Turbo molecular pump, 27 ... rotary pump, 30, 31 ... gas nozzle,
32, 33 ... Gas valve, 34, 35 ... Gas flow controller, 36, 37 ... Gas valve, 38, 39 ... Gas cylinder, 40 ... Sample, 41 ... Observation part, 42 ... Projection part, 43 ...
Sample holder, 44 ... Electron beam, 45 ... Reactive gas, 4
6 ... Unprocessed area, 47 ... Shaded area for electron beam irradiation, 4
8 ... Processing area, 48a ... Rough processing area, 48b ... Finishing processing area, 49 ... Electron beam irradiation direction, 50 ... Liquid metal ion source, 51 ... Extraction electrode, 53 ... First lens electrode, 5
6 ... Deflection electrode, 57 ... Second lens electrode, 58 ... Secondary electron detector, 59 ... Sample, 70 ... Ion beam diameter, 72 ... Electron beam diameter, 73 ... Observation portion of TEM sample, 74 ... Thickness of observation portion 90 ... GaAs substrate, 91a, 91b, 9
1c, 91d ... AlGaAs layer, 92a, 92b, 92
c ... GaAs layer, 93 ... Si substrate, 94 ... Sin + layer,
95 ... SiO ₂ , 96 ... Al wiring, 97 ... PSG, 98
... SiO ₂ , 99 ... poly-Si gate, 100 ... dark area, 1
01 ... Supply pipe, 102 ... Gas nozzle, 110, 111,
112, 113, 115 ... SEM images, 114, 116 ...
STEM images 117, 118, 119 ... SEM images, 12
1 ... Image memory, 122 ... A / D converter, 123 ... SE
M image, 124 ... STEM image, 125 ... Dark part, 130 ... Electron source, 131 ... Condenser lens, 132 ... Scan coil, 133 ... Objective lens, 134, 135 ... Gas nozzle, 136 ... Sample holder, 137 ... Secondary electron detector 1
38 ... Transmission electron detector, 139 ... Ion pump, 140
… Turbo molecular pump, 141… Rotary pump, 142
… Turbo molecular pump, 143… Rotary pump, 14
4, 145 ... Valve, 146 ... Anode, 147 ... Sample chamber

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location H01J 37/20 H01J 37/244 37/244 G01N 1/28 F (72) Inventor Junzo Higashi Kanagawa 292 Yoshida-cho, Totsuka-ku, Yokohama-shi Incorporated company Hitachi, Ltd.

Claims (7)

[Claims] 1. A sample is positioned by a secondary electron image of the sample, the sample is irradiated with an electron beam in a reactive gas atmosphere, and reactive etching is locally performed at a portion irradiated with the electron beam so that the sample has a predetermined thickness. A process for preparing an observation sample, which comprises subjecting the reaction gas to processing, evacuating the reactive gas after the processing, and observing with a transmission electron microscope. 2. The observation sample preparation method according to claim 1, wherein when the sample is irradiated with an electron beam, a sample irradiation surface of the electron beam is used as an observation surface of a transmission electron microscope, and a processed state is obtained by observing the transmission electron microscope image. A method for preparing an observation sample, characterized in that the sample is processed into a predetermined thickness based on the above. 3. The observation sample preparation method according to claim 2, wherein the transmitted electron intensity is measured when the sample is processed. 4. The method for preparing an observation sample according to claim 1, wherein the electron beam is formed by two electron optical systems whose optical axes are orthogonal to each other, and a transmission electron microscope image of the sample is observed by one electron optical system. An observation sample preparation method characterized by processing the sample with an electron beam of another electron optical system based on the observation. 5. An electron source for generating electrons, a sample holder for mounting a sample, a sample chamber for loading the sample holder, an irradiation lens system for irradiating the sample with an electron beam from the electron source, and the irradiation. An imaging lens system for forming an image of transmitted electrons from the received sample, an observation chamber for observing the formed transmitted electron microscope image, and detecting secondary electrons and transmitted electrons from the irradiated sample, respectively. A scanning transmission electron microscope comprising a secondary electron detector and a transmission electron detector, a gas supply means for supplying a reactive gas to the sample, a rotating means for rotating the sample holder, and the secondary electron An observation sample preparation device comprising a detector and setting means for determining a processing range of the sample from respective image data based on detection signals of the transmission electron detector. 6. An electron source for generating electrons, a sample holder for mounting a sample, a sample chamber for loading the sample holder, an irradiation lens system for irradiating the sample with an electron beam from the electron source, and the irradiation. A scanning electron microscope comprising a secondary electron detector for detecting secondary electrons from the sample that has received the gas, a gas supply system for supplying a reactive gas to the sample, and a transmission for detecting transmitted electrons from the sample. An electron detector, rotation means for rotating the sample holder, and means for setting the processing range of the sample from the image data by the detection signal of the secondary electron detector and the detection signal intensity of the transmission electron detector are provided. An observation sample preparation device characterized in that 7. An electron source for generating electrons, a sample holder for mounting a sample, a sample chamber for loading the sample, an irradiation lens system for irradiating the sample with an electron beam from the electron source, and the irradiation. An image forming lens system for forming an image of transmitted electrons from the received sample, and a transmission electron microscope including an observation chamber for observing the formed transmission electron microscope image are provided, and the transmission electron microscope is arranged at right angles to the electron optical system of the transmission electron microscope. An arranged electron source, an irradiation lens system that irradiates the sample with an electron beam from the electron source, a gas supply system that supplies a reactive gas to the sample, and a secondary device that detects secondary electrons from the sample. An observation sample preparation device comprising an electron detector and means for setting a processing range of the sample from image data obtained by detection signals from the secondary electron detector.