JP3494208B2 - Scanning electron microscope - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning electron microscope which scans an electron beam spot on a sample surface to obtain a scanning image of the sample surface, and is particularly suitable for observing a sample region including a contact hole and a resist residue. It relates to a scanning electron microscope.

[0002]

2. Description of the Related Art Conventionally, for observation or measurement of a submicron order (1 μm or less) contact hole or line pattern in a semiconductor device sample,
A scanning electron microscope is used.

In a scanning electron microscope, an electron beam emitted from a heating type or field emission type electron source is scanned on a sample to detect signals (secondary electrons and backscattered electrons) that are secondarily obtained. By using the secondary signal as the luminance modulation input of the cathode ray tube which is scanned in synchronization with the scanning of the electron beam, the scanning image (SEM
Image). In a general scanning electron microscope, electrons emitted from an electron source are accelerated between an electron source to which a negative potential is applied and an anode at a ground potential to irradiate a test sample at the ground potential.

In recent years, a scanning electron microscope has come to be used in a semiconductor manufacturing process or an inspection process after completion (for example, inspection of electric operation by an electron beam), so that an insulator can be observed without being charged. As possible, a high accelerating voltage of 1000 V or less and a high resolution of 10 nm or less have been required.

That is, a semiconductor device sample is generally formed by laminating an electrical insulator such as SiO2 or SiN on a conductor portion such as Al or Si. When such a semiconductor device sample is irradiated with an electron beam, the surface of the electric insulator is negatively charged (hereinafter sometimes simply referred to as charge-up), the trajectory of the emitted secondary electrons is changed, or the primary electron is changed. The orbit of the electron beam itself will change. As a result, abnormal contrast occurs in the SEM image, or severe distortion occurs.

The image failure caused by such charge-up seriously hinders the observation of contact holes and the measurement of line and space, which makes it difficult to evaluate the semiconductor manufacturing process and also the quality of the semiconductor device itself. It will be a big obstacle in securing. Therefore, conventionally, the energy of the primary electron beam with which the sample is irradiated is 1K.
A so-called low acceleration SEM having an eV or less was used.

However, the above-mentioned prior art has the following problems. That is, when the accelerating voltage is lowered, the resolution is remarkably lowered due to the chromatic aberration caused by the electron beam energy variation, and it becomes difficult to observe at high magnification. Also,
When the electron current decreases, the ratio of secondary signal to noise (S /
N) is remarkably lowered, the contrast as an SEM image is deteriorated, and it becomes difficult to observe at high magnification and high resolution. In particular, in a semiconductor device manufactured by ultra-fine processing technology, a signal generated from a concave portion such as a contact hole or a line pattern becomes weak, which is a great obstacle to fine observation and length measurement.

As a method for solving such a problem, for example, I Triple E, 9th Annual Symposium on Electron Ion and Laser Beam Technology Proceedings, pages 176 to 186 (IEEE 9th Annual Symposium on Electron, Ion)
and Laser Technology), the acceleration voltage between the electron source and the anode at the ground potential is set high, and a deceleration electric field is generated between the objective lens at the ground potential and the test sample to which a negative potential is applied to generate a deceleration electric field on the sample. A scanning electron microscope has been proposed in which the irradiation electron beam is decelerated to finally set a relatively low acceleration voltage to achieve both reduction of chromatic aberration and prevention of charge-up.

[0009]

The above-mentioned conventional scanning electron microscope decelerates the primary electron beam with which the sample is irradiated, while generating electrons from the sample due to the irradiation with the primary electron beam as an electron source. Strongly accelerate in the direction. In this case, in a detector having a detection surface facing the sample surface, secondary electrons given high acceleration energy and reflected electrons originally having high acceleration energy similarly rush into the detection surface.

In such a state, there is a problem that the information of the backscattered electrons is not reflected in the sample image due to the influence of the secondary electrons which are emitted from the sample in a larger amount than the backscattered electrons. Compared to secondary electrons, backscattered electrons are more suitable for observing the bottom of contact holes, etc., and compared to secondary electrons, the contrast between the residue of the resist adhering on the sample and other parts is clearer. Therefore, discrimination detection from secondary electrons is desired.

As described above, since the amount of emitted backscattered electrons is smaller than that of secondary electrons, the backscattered electron image shows the secondary electrons.
It lacks brightness and contrast compared to electronic images
There was a problem.

An object of the present invention is to solve the problems of the above-mentioned conventional techniques and to provide a trial that includes the unique information of backscattered electrons.
An object of the present invention is to provide a scanning electron microscope capable of forming a material image with sufficient brightness .

In the present invention, in order to achieve the above object, an objective lens for converging the electron source, a primary electron beam that will be emitted from the electron source, due to the irradiation of the primary electron beam
In an electron microscope equipped with an electron detector for detecting electrons emitted from a sample and a negative voltage applying means for applying a negative voltage to the sample and / or a sample table on which the sample is arranged .
The electron detector is closer to the electron source than the objective lens.
And is outside the axis of the primary electron beam,
The portion that receives the electron in the direction intersecting with the primary electron beam
Spread and placed between the part that receives the electrons and the sample
And is emitted from the sample by the negative voltage applying means.
Secondary electrons accelerated by the electric field generated by the negative voltage
Decelerate the acceleration of backscattered electrons, and
Of the backscattered electrons, the backscattered electrons pass through and the secondary electrons pass through.
An energy filter to which a negative voltage is applied to limit the excess,
Means for adjusting the negative voltage .

Here, since the reflected electrons are excellent in straightness and less likely to be caught on the side wall of the contact hole as compared with the secondary electrons, they are suitable for observing the bottom of the contact hole. Further, the reflected electrons can clarify the contrast between the residue of the resist attached on the sample and other elements. On the other hand, secondary electrons, which have a large amount of reflected electrons, are suitable for obtaining the brightness of the sample image.

The present invention is applied to an energy filter.
It is possible to change the ratio of secondary electrons to the backscattered electrons detected by the electron detector, and to adjust the ratio of secondary electrons within the range where the contact hole can be observed. by increasing the bright observation and portions other than the contact hole of the contact hole bottom
Since it is possible to improve both the roughness and the
It is possible to obtain the resolution of .

That is, the ratio of the secondary electrons detected by the electron detector is appropriately selected in order to achieve both the observation of the bottom of the contact hole by the reflected electrons and the high resolution of the area other than the contact hole by the secondary electrons. It will be possible.

Further, by increasing the ratio of secondary electrons within the range where the resist portion and the other portion can be discriminated, high resolution observation of the entire sample image becomes possible.

[0018]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a scanning electron microscope system according to an embodiment of the present invention. The system is a scanning electron microscope body 100 and a sample exchange mechanism 20.
It consists of zero. FIG. 2 is a diagram showing in detail the configuration of the scanning electron microscope main body 100 of FIG.

In FIG. 2, a cathode 1, an extraction electrode 2, and an anode 3 constitute a field emission type electron gun, an extraction voltage 4 is applied between the cathode 1 and the extraction electrode 2, and the cathode 1 is accelerated. Voltage 5 is applied. Electron beam 20 emitted from cathode 1
a is further accelerated by the voltage applied between the extraction electrode 2 and the anode 3 at the ground potential. Therefore, the energy (acceleration voltage) of the electron beam that has passed through the anode 3 matches the acceleration voltage 5. Further, since the negative superposed voltage 6 is applied to the sample 18 via the sample holder 21 and a deceleration electric field is formed between the objective lens 17 and the sample 18, the electron beam irradiated on the sample 18 is accelerated. The voltage is a voltage obtained by subtracting the superimposed voltage 6 from the acceleration voltage 5.

Electron beam 20b accelerated through the anode 3
Are converged on the sample 18 by the condenser lens 7 and the objective lens 17. The electron beam that has passed through the objective lens 17 is decelerated by the deceleration electric field formed between the objective lens 17 and the sample 18, and the sample 18 has energy substantially equivalent to the voltage obtained by subtracting the superimposed voltage 6 from the acceleration voltage 5. To reach.

The aperture angle of the electron beam at the objective lens 17 is determined by the diaphragm 8 arranged below the condenser lens 7. The centering of the diaphragm 8 is performed by operating the adjusting knob 10.

The accelerated electron beam 20b is emitted from the upper scanning coil 1
The convergent electron beam 20c which is deflected by the first and lower scanning coils 12 and decelerated by the deceleration electric field is raster-scanned on the sample 18. In the present embodiment, the scanning coil has a two-stage configuration so that the scanned electron beam always passes through the lens center of the objective lens 17.

The sample 18 is fixed by a sample holder 21, and the sample holder 21 is placed on a sample stage 19 which can be adjusted in position such as horizontal adjustment via an insulating base 9. The superimposed voltage 6 is applied to the sample holder 21.

The secondary electrons 24 emitted from the sample 18 by being irradiated with the decelerated electron beam 20c are accelerated by the decelerating electric field created between the objective lens 17 and the sample 18 and are attracted into the objective lens 17, and , Ascends while spiraling under the influence of the magnetic field of the objective lens 17.

Secondary electrons 24 passing through the objective lens 17
Is attracted by a suction electrode 13 provided outside the electron beam passage between the objective lens 17 and the lower scanning coil 12 and applied with a positive potential, and is accelerated by a scintillator 14 applied with 10 kV (positive potential). Light the scintillator.

The emitted light is guided to the photomultiplier tube 16 by the light guide 15 and converted into an electric signal. The output of the photomultiplier tube 16 is further amplified and becomes the luminance modulation input of the cathode ray tube, but it is not shown here.

According to the scanning electron microscope having such a configuration, the energy of the electron beam (electron beam 20b) when passing through the condenser lens 7, the diaphragm 8 and the objective lens 17 is the final stage electron beam (electron beam 20c). Since the energy is higher than the energy of, the chromatic aberration was improved and high resolution was obtained.

Moreover, since the primary electron beam with which the sample is irradiated is decelerated to have low energy, charge-up of the sample is also eliminated.

Specifically, the beam diameter which was 15 nm when only the acceleration voltage (500 V) was applied was improved to 10 nm by adding the acceleration voltage (1000 V) and the superimposed voltage 6 (500 V).

Further, in FIG. 1, a field emission cathode 1, an extraction electrode 2, an anode 3, a condenser lens 7, an objective lens 1
Components such as the sample 7, the sample 18, the sample holder 21, the insulating base 9, and the sample stage 19 are housed in the vacuum housing 61.
The vacuum exhaust system is not shown.

Here, when a negative voltage is applied to the sample 18, it is necessary to avoid exchanging the sample by the sample exchanging mechanism 77 and exposing the vacuum housing 61 to the atmosphere. In other words, the superimposed voltage 6 may be applied only when the electron beam is scanning the sample 18.

Therefore, in the present invention, it is provided between the cathode 1 and the sample 18 under the first condition that the switch S1 is closed and the accelerating voltage 5 is applied, which is a preparatory operation at the time of mounting and exchanging the sample. The second condition in which both the valve G1 and the valve G2 are opened and the third condition in which the valve G3 that the sample exchange mechanism 77 passes to place the sample 18 on the sample stage 19 are closed are satisfied. Switch S only when
2 is closed and the control of applying the superimposed voltage 6 to the sample 18 is performed.

Further, the sample holder 21 and the sample stage 19
Are electrically connected via a discharge resistor R, and when the switch S2 is opened, the charge charged in the sample 18 has a constant time constant via the sample holder 21, the discharge resistor R, and the sample stage 19. The discharge is promptly caused by and the potential of the sample 18 is lowered.

The acceleration voltage 5 can be applied under the condition that the vacuum around the cathode 1 is the set value or more, or only when the vacuum of the vacuum casing 61 is the set value or more.
It goes without saying that a normal sequence is set up in which 2 is opened.

In this embodiment, the superposed voltage 6 is applied when all of the above three conditions are satisfied, but when one or two of these conditions are satisfied. Alternatively, the switch S2 may be closed.

FIG. 3 is a block diagram of a main part of a scanning electron microscope according to the second embodiment of the present invention, and the same reference numerals as those used above represent the same or equivalent parts.

In the first embodiment described above, the secondary electrons 24 were taken out of the electron passage by the suction electrode 13 and detected, but in the present embodiment, the secondary electrons are detected using the channel plate detector 26. The feature is that it is done.

In the figure, a disc-shaped channel plate body 25 having a central hole 33 is provided between the objective lens 17 and the lower scanning coil 12. The diameter of the central hole 33 is set so that the electron beam 20b deflected by the scanning coil 12 does not collide with it. A mesh 34 is provided below the channel plate body 25.

In such a structure, the accelerated electron beam 20b passes through the central hole 33 of the channel plate, is converged by the objective lens 17, and is irradiated onto the sample 18. The secondary electron 24 generated in the sample 18 is the objective lens 17
At the same time, the lens is subjected to a lens action, and while diverging, passes through the mesh 34 placed on the entire surface and enters the channel plate 25. The secondary electrons 24 incident on the channel plate 25 are amplified by the amplified voltage 2 applied to both ends of the channel plate 25.
It is accelerated and amplified at 8. The amplified electrons 27 are further accelerated by the anode voltage 29 and captured by the anode 37.

The secondary electrons thus captured are amplified by the amplifier 30 and then converted into light 32 by the optical conversion circuit 31. Light 32
The reason why the conversion is converted into is because the amplifier 30 is in a floating state by the amplified voltage 28 of the channel plate 25 and the like.

The light 32 is converted into an electric signal again by the electric conversion circuit 35 of ground potential, and is used as a brightness modulation signal of the scanning image. With this method, not only secondary electrons but also reflected electrons can be detected.

As is apparent, this embodiment also achieves the same effect as described above.

FIG. 4 is a block diagram of a main part of a scanning electron microscope according to a third embodiment of the present invention, and the same reference numerals as those used above represent the same or equivalent portions. In this embodiment,
The feature is that a desired secondary signal can be selectively detected.

In the figure, a filter voltage 36 whose potential can be arbitrarily controlled is applied to the channel plate 25. For example, if the filter voltage 36 is set to a negative voltage of about 10 V more than the superposed voltage 6, of the secondary electrons and reflected electrons emitted from the sample, the secondary electrons are generated between the channel plate 25 and the mesh 34. Only the backscattered electrons with high energy can be selectively detected by being driven back by the reverse electric field.

Further, it is possible to know the potential of the sample by measuring the limit filter voltage 36 for repelling secondary electrons. By adding such a function, the function inspection of the completed semiconductor element can be performed. Will be able to.

FIG. 5 is a block diagram of a scanning electron microscope according to a fourth embodiment of the present invention, in which the same symbols as those used above represent the same or equivalent portions. This embodiment is characterized in that an energy filter (potential barrier) is provided above the objective lens 17. Further, in the present embodiment, an example in which the sample 18 is applied to the in-lens method in which the sample 18 is arranged inside the objective lens 17 is shown.

The energy filter comprises a cylinder 46 for passing primary electrons, a set of shield grids 41, and an energy filter 42. As in the case of the third embodiment described with reference to FIG. 3 above, also in this embodiment, the potential of the sample 18 can be measured by controlling the filter voltage 36 and appropriately adjusting the potential of the energy filter 42. Become.

Further, in this embodiment, by properly selecting the voltage of the suction electrode 13, it becomes possible to selectively detect only the secondary electrons without detecting the reflected electrons.

In this in-lens system, the sample stage 1
9 is placed inside the objective lens 17, and the sample 18 is fixed via the insulating base 9 and the sample holder 21. The superimposed voltage 6 is applied to the sample holder 21, and a deceleration electric field is created between the sample 18 and the objective lens 17. Objective lens 1
The excitation coil 45 of No. 7 is fixed to the upper part of the objective lens 17. The objective lens 17 is large enough to accommodate an 8-inch wafer.

FIG. 6 is a block diagram of a scanning electron microscope according to a fifth embodiment of the present invention, in which the same symbols as those used in the previous description represent the same or corresponding portions. This embodiment is characterized in that an inconvenient sample can be observed when a strong electric field is applied.

In a semiconductor integrated circuit, an element may be damaged by a strong electric field. In order to solve such problems,
In this embodiment, a control electrode 39 is provided between the objective lens 17 and the sample 18, and a control voltage 40 to several tens of volts is applied to the control electrode 39.

According to the present embodiment, the electric field generated between the objective lens 17 and the sample 18 is relaxed by the control electrode 39, and the element can be prevented from being damaged.

FIG. 7 is a block diagram of a scanning electron microscope according to a sixth embodiment of the present invention, in which the same symbols as those used above represent the same or equivalent portions.

In the above-described first and fourth embodiments, the secondary signal is deflected by utilizing the electric field, and this is detected by the detector. In this embodiment, the secondary signal is utilized by using the magnetic field and the electric field. The feature is that the next signal is deflected.

When the acceleration voltage increases and the reduction ratio of the electron beam in the final stage due to the deceleration electric field decreases, the energy difference between the primary electron beam 20b with which the sample is irradiated and the secondary electron 24 emitted from the sample decreases. So the secondary electron 24
When a relatively large electric field E is generated by the attraction electrode 13 in order to attract the
Will also be bent.

The present embodiment was made in order to solve such a problem, and paying attention to the fact that the deflection direction of the electron beam due to the magnetic field differs depending on the traveling direction of the electron beam, and the electric field E
The deflection of the primary electron beam 20b due to is canceled and a magnetic field B is generated so as to supplement the deflection amount of the secondary electron 24.

That is, in this embodiment, the primary electron beam 20b
However, the magnetic field B is generated so as to be deflected in the direction opposite to the deflection direction by the electric field E generated by the suction electrode 13. Therefore, by appropriately controlling the strength of the magnetic field B, the deflection of the electron beam 20b by the electric field E is canceled.

On the other hand, with respect to the secondary electrons 24, the deflection direction by the magnetic field B and the deflection direction by the electric field E are the same, so that the deflection amount of the secondary electrons is large and the detection of the secondary electrons is easy. become.

FIG. 8 is a block diagram of a scanning electron microscope according to a seventh embodiment of the present invention, in which the same symbols as those used in the previous description represent the same or corresponding portions. The present embodiment is characterized in that a single crystal scintillator is used to detect a secondary signal.

In the figure, the single crystal scintillator 55
Is an opening 5 for obliquely cutting a cylindrical YAG single crystal and passing the primary electron 20b through the cut surface.
7, a conductive thin film 56 of metal, carbon, or the like is coated on the tip end portion thereof, and the ground potential is applied.

In this embodiment, the crossover 58 of the primary electron beam 20b formed by the condenser lens 12 is formed in the opening 5.
7, so that the crossover 59 of the secondary electron 24 by the objective lens 17 is located at a position away from the opening 57. In this way, the primary electron beam 20
The secondary electron 24 can be efficiently detected without being blocked by the opening 57.

In the eighth embodiment described above, the light emitting portion and the light guide of the scintillator are both made of YAG single crystal, but only the light emitting portion for detecting secondary electrons is made of YAG single crystal. The other portions may be made of a transparent member such as glass or resin.

FIG. 9 is a block diagram of a main part of a scanning electron microscope according to an eighth embodiment of the present invention, and the same reference numerals as those used above represent the same or equivalent parts.

In this embodiment, the anode constituting the electron gun is omitted, and the electron beam is accelerated by the extraction voltage 4 applied between the grounded extraction electrode 2 and the cathode 1. The electrons accelerated by the extraction voltage 4 are converged by the objective lens 17 and travel toward the sample 18. The positive electrode side of the acceleration voltage 5 is connected to the sample 18. At this time, since the extraction voltage 4 is higher than the acceleration voltage 5 in the low acceleration voltage region, the electron beam is decelerated to the acceleration voltage 5 between the objective lens 17 and the sample 18 and reaches the sample.
In a typical example using a field emission cathode, the extraction voltage is 3k.
V, accelerating voltage is 1 kV. With such a configuration, the anode and the superimposed voltage source are omitted, so that the configuration is simplified.

[0065]

According to the present invention, it is possible to satisfactorily observe the bottom of a contact hole and the residue of a resist.
In addition, the brightness of other parts can be improved.
Therefore, it is possible to obtain the resolution that the device has.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a scanning electron microscope which is an embodiment of the present invention.

FIG. 2 is a configuration diagram of a scanning electron microscope unit in FIG.

FIG. 3 is a configuration diagram of a scanning electron microscope section that is a second embodiment of the present invention.

FIG. 4 is a configuration diagram of a scanning electron microscope section that is a third embodiment of the present invention.

FIG. 5 is a configuration diagram of a scanning electron microscope section that is a fourth embodiment of the present invention.

FIG. 6 is a configuration diagram of a scanning electron microscope section that is a fifth embodiment of the present invention.

FIG. 7 is a configuration diagram of a scanning electron microscope section that is a sixth embodiment of the present invention.

FIG. 8 is a configuration diagram of a scanning electron microscope section that is a seventh embodiment of the present invention.

FIG. 9 is a configuration diagram of a scanning electron microscope section that is a ninth embodiment of the present invention.

[Explanation of symbols]

1 ... Cathode, 2 ... Extraction electrode, 3 ... Anode, 4 ... Extraction voltage, 5
… Accelerating voltage, 6… Superposed voltage, 7… Condenser lens, 8
... diaphragm, 9 ... insulation stand, 10 ... adjustment knob, 11 ... upper scanning coil, 12 ... lower scanning coil, 13 ... suction electrode, 14 ...
Scintillator, 15 ... Light guide, 16 ... Photomultiplier tube,
17 ... Objective lens, 18 ... Sample, 19 ... Sample stage,
20 ... Primary electron beam, 21 ... Sample holder, 24 ... Secondary electron, 25 ... Channel plate, 28 ... Amplification voltage, 29
... Anode voltage, 30 ... Amplifier, 31 ... Optical conversion circuit, 3
3 ... central hole, 34 ... mesh, 35 ... electrical conversion circuit, 3
6 ... Filter voltage, 37 ... Anode, 39 ... Control electrode,
40 ... Control voltage, 41 ... Shield grid, 42 ... Energy filter, 55 ... Single crystal scintillator, 56 ... Conductive thin film, 61 ... Housing, 77 ... Sample exchange mechanism

─────────────────────────────────────────────────── --Continued from the front page (56) References JP-A-1-298633 (JP, A) JP-A-3-49142 (JP, A) JP-A 63-146336 (JP, A) JP-A 63- 108655 (JP, A) JP 62-50672 (JP, A) JP 3-295142 (JP, A) JP 47-8874 (JP, B2) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01J 37/244 H01J 37/28

Claims (7)

(57) [Claims] 1. A electron source and, electrostatic released an objective lens for converging an <br/> following electron beam that will be emitted from the sample due to the irradiation of the primary electron beam from the electron source <br / > An electron microscope provided with an electron detector for detecting a child, and a negative voltage applying means for applying a negative voltage to the sample and / or a sample table on which the sample is arranged
Where the electron detector is located closer to the electron source than the objective lens is.
And the primary electron beam is off-axis
The part that receives the electrons spreads in the direction that intersects the electron beam.
Is placed between the part that receives the electrons and the sample, and
The negative voltage emitted from the sample by the negative voltage applying means.
Secondary electrons and backscattered electrons accelerated by the electric field generated by
Of the secondary electrons and reflections
Restricts secondary electrons from passing through backscattered electrons
And a means for adjusting the negative voltage, and a scanning electron microscope. 2. The scanning electron microscope according to claim 1, wherein the portion that receives the electrons is a part of a channel plate. 3. The scanning electron microscope according to claim 1, wherein the portion that receives the electrons is a part of a scintillator. 4. The scanning electron microscope according to claim 1, wherein the energy filter includes a mesh electrode. 5. The energy filter according to claim 1,
The negative voltage applied to the filter causes the sample and / or
Negative voltage applied to the sample table on which the sample is placed and 10V
A scanning electron microscope, which is a superposed voltage with a negative voltage of a certain degree . 6. An electron source, an objective lens for converging a primary electron beam emitted from the electron source, and an electron emitted from the sample due to irradiation of the primary electron beam.
An electron detector for detecting a child, retarding field type for forming a decelerating field for the primary electron beam
In the electron microscope provided with the above-mentioned means, the electron detector is arranged closer to the electron source than the objective lens.
At the same time as the primary electron beam outside the axis of the primary electron beam.
The part that receives the electrons spreads in a direction intersecting the sagittal line, and an energy gap is provided between the part that receives the electrons and the sample.
A filter is arranged and the energy filter is
It is larger than the negative voltage that forms the fast electric field and is discharged from the sample.
Of the emitted secondary electrons and reflected electrons, it passes through the reflected electrons.
Adjust the negative voltage to limit the passage of secondary electrons
A scanning electron microscope characterized in that a variable power supply included in the range is connected . 7. A electron source, electrostatic released an objective lens for converging the primary electron beam that will be emitted from the sample due to the irradiation of the primary electron beam from the electron source
The electron detector that detects the child and the sample and / or the sample table on which the sample is placed.
In an electron microscope equipped with a negative voltage applying means for applying a voltage
The electron detector is closer to the electron source than the magnetic pole end of the objective lens.
And is outside the axis of the primary electron beam,
A portion for receiving the electron in a direction intersecting with the primary electron beam
Enerugifu Between spread, between the portion for receiving said electrons and said sample
Filter, and the energy filter is
Negative and / or negative applied to the sample stage on which the sample is placed
Secondary electrons emitted from the sample that are larger than the voltage
Of the secondary and secondary electrons
A variable power supply whose regulation range includes a negative voltage that limits the passage
A scanning electron microscope characterized by being connected .