JP2020008516A - Sample analyzer, electron microscope and focusing mirror unit - Google Patents

Abstract

To irradiate decelerated charged particles to a sample so as not to lower detection efficiency of cathode luminescence.SOLUTION: A sample analyzer 100 for analyzing a sample W by detecting light emitted from the sample W which is irradiated with charged particles, includes an irradiation part 3 for irradiating the sample W with the charged particles, and a focusing mirror 41 provided between the irradiation part 3 and the sample W, for focusing light emitted from the sample W, in which a deceleration electric field for decelerating the charged particles is generated between the irradiation part 3 and the focusing mirror 41.SELECTED DRAWING: Figure 4

Description

  The present invention is applied to, for example, a sample analyzer that detects light emitted from a sample irradiated with an electron beam or an ion beam and analyzes the sample, an electron microscope using the sample analyzer, and the sample analyzer. Related to a condensing mirror unit to be used.

  As this type of sample analyzer, there is a so-called cathodoluminescence analyzer which collects and detects cathodoluminescence (CL) generated by irradiating a sample with charged particles by a condensing mirror.

  The cathodoluminescence analyzer disclosed in Patent Literature 1 is configured to apply a retarding voltage to a sample to decelerate charged particles immediately before the sample, so that the sample surface can be observed with a low acceleration voltage.

  When the retarding voltage is applied to the sample in this manner, an electric field is generated between the sample and the focusing mirror. At this time, if the potential of the light collecting mirror is, for example, zero, the electric field is attracted to the light collecting mirror and is distorted along the mirror surface. As a result, the trajectory of the charged particles toward the sample is bent, and the obtained image is distorted.

  In view of this, the cathodoluminescence analyzer disclosed in Patent Literature 1 prevents an electric field from being attracted to the converging mirror by providing an intermediate member between the sample and the converging mirror. In addition, a plurality of holes are formed in the intermediate member, and an electric field is generated between the intermediate member and the sample such that the charged particles hardly bend, thereby preventing the above-described image distortion.

  However, in the above-described configuration, a part of the cathodoluminescence generated from the sample and heading toward the condensing mirror is blocked by the intermediate member, and a new problem arises in that the cathodoluminescence detection efficiency is reduced.

International Publication WO2017 / 131132

  Therefore, the present invention is to solve the above problems at once, without reducing the efficiency of detecting the cathodoluminescence, the main problem is to reduce the speed of the charged particles and irradiate the sample. Is what you do.

  That is, the sample analyzer according to the present invention is a sample analyzer that analyzes the sample by detecting light emitted from the sample irradiated with the charged particles, and an irradiation unit that irradiates the sample with the charged particles; A converging mirror provided between the unit and the sample, and condensing light emitted from the sample, and a deceleration electric field for decelerating the charged particles is generated between the irradiation unit and the condensing mirror. It is characterized by having such a configuration.

  With such a sample analyzer, a deceleration electric field is generated between the irradiation unit and the condensing mirror, that is, on the back side of the mirror surface of the condensing mirror, so that no member is required between the condensing mirror and the sample. In addition, it is possible to prevent the deceleration electric field from being distorted along the mirror surface of the condenser mirror. Thus, for example, by applying a retarding voltage to the sample, the charged particles can be decelerated and irradiated to the sample, while preventing a decrease in the efficiency of detecting the cathodoluminescence.

It is preferable that the apparatus further includes a retarding voltage application unit that applies a retarding voltage for decelerating the charged particles to the sample or a sample stage on which the sample is mounted, and the condensing mirror.
With such a configuration, a retarding electric field is generated between the irradiation unit and the condenser mirror due to the retarding voltage, so that the charged particles can be decelerated immediately before the condenser mirror. Moreover, by applying the same amount of retarding voltage to the sample or sample stage and the focusing mirror, no electromagnetic force acts on the charged particles between them, and the charged particles do not bend their trajectories. It can be guided to the sample, and image distortion can be suppressed.

By the way, if a deceleration voltage is generated between the irradiation part and the condensing mirror only by the above-described retarding voltage, the decelerating electric field wraps around the mirror surface side of the condensing mirror, and the decelerated electric field is charged by the wrapped deceleration electric field. The trajectory of the particles may be bent.
Therefore, it is preferable to include an electrostatic lens provided between the irradiation unit and the condenser mirror, and a deceleration voltage application unit that applies a deceleration voltage for decelerating the charged particles to the electrostatic lens.
With such a configuration, the deceleration electric field is adjusted on the mirror surface side of the focusing mirror by adjusting the deceleration voltage and the arrangement of the electrostatic lens so that a deceleration electric field is generated mainly between the electrostatic lens and the irradiation unit. It is possible to prevent sneaking around.

As a specific embodiment, the irradiation unit has an objective lens through which the charged particles pass, and the electrostatic lens is provided between the objective lens and the condenser mirror, It is preferable that the center axis of the lens and the center axis of the electrostatic lens are coaxial.
With such a configuration, the charged particles can be collected or diverged by the electrostatic lens without bending the trajectory of the charged particles.

  An electron microscope equipped with the above-described sample analyzer is also one of the present invention.

Further, the condensing mirror unit according to the present invention includes an irradiation unit for irradiating the sample with charged particles, and a sample analyzer for analyzing the sample by detecting light emitted from the sample irradiated with the charged particles. A condensing mirror unit that is used, provided between the irradiation unit and the sample, a condensing mirror that condenses light emitted from the sample, and a retarding voltage that decelerates the charged particles, It is characterized by comprising a sample or a sample stage on which the sample is placed, and a retarding voltage applying unit for applying the sample to the focusing mirror.
By using such a condensing mirror unit, the same operation and effect as those of the above-described sample analyzer can be obtained.
With such a configuration, a retarding electric field is generated between the irradiation unit and the condenser mirror due to the retarding voltage, so that the charged particles can be decelerated immediately before the condenser mirror. Moreover, by applying the same magnitude of retarding voltage to the sample or sample stage and the focusing mirror, no electromagnetic force acts on the charged particles between them, and the charged particles do not bend their trajectories. It can be guided to the sample, and image distortion can be suppressed.

  According to the present invention configured as described above, the charged particles can be irradiated onto the sample at a reduced speed without reducing the detection efficiency of the cathode luminescence.

FIG. 1 is a schematic diagram illustrating a configuration of a sample analyzer according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing a peripheral configuration of a condenser mirror of the embodiment. FIG. 4 illustrates an example of an electric field generated by a retarding voltage. The figure explaining the electric field produced by the retarding voltage and the deceleration voltage. FIG. 9 is a schematic diagram illustrating a peripheral configuration of a condenser mirror according to a modified embodiment. FIG. 9 is a schematic diagram illustrating a peripheral configuration of a condenser mirror according to a modified embodiment. The schematic diagram which shows the structure of a plate-shaped member in a modified embodiment. FIG. 9 is a schematic diagram illustrating a peripheral configuration of a condenser mirror according to a modified embodiment. FIG. 9 is a schematic diagram illustrating a configuration of a detection device according to a modified embodiment.

  Hereinafter, an embodiment of a sample analyzer according to the present invention will be described with reference to the drawings.

<Apparatus configuration>
The sample analyzer 100 according to the present embodiment is incorporated in an electron microscope, and a cathode generated from the sample W by irradiating the sample W such as a semiconductor wafer with an electron beam (energy beam) EB that is a charged particle beam. This is a so-called cathodoluminescence analyzer that uses a luminescence CL to evaluate physical properties and analyze a semiconductor element in a minute region of the sample W.

  Specifically, as shown in FIG. 1, a vacuum chamber 2 for accommodating a sample W, and an electron beam irradiator 3 as an irradiation unit for irradiating the sample W accommodated in the vacuum chamber 2 with an electron beam EB. And a detection device 4 serving as a light detection unit for separating and detecting the cathode luminescence CL generated from the sample W by the irradiation of the electron beam EB, and receiving an output signal from the detection device 4 to evaluate the sample W ( For example, an information processing device 5 that performs predetermined arithmetic processing for performing stress measurement).

  Hereinafter, each of the units 2 to 5 will be described with reference to FIG.

  The vacuum chamber 2 includes a container that stores the sample W to be irradiated with the electron beam EB, a vacuum pump that evacuates the container, and a sample table 201 on which the sample W is placed.

The electron beam irradiation device 3 includes, for example, a thermal field emission type electron gun 31, a lens mechanism for converging an electron beam EB emitted from the electron gun 31 to a predetermined portion of the sample W, and a scanning mechanism for scanning the electron beam EB. An electron beam control mechanism 32 including an electron gun 31 and a lens barrel 33 which is a housing member having the electron beam control mechanism 32 therein. The lower end of the lens barrel 33 is provided continuously to the upper wall of the vacuum chamber 2. Note that the electron beam control mechanism 32 may be partially or entirely provided outside the lens barrel 33.
As the scanning mechanism, for example, a mechanism using a scanning coil that deflects the electron beam EB in the scanning direction is used. Further, as the lens mechanism, a lens mechanism using a condenser lens or an objective lens may be used.

  The detection device 4 includes a condenser mirror 41, an optical fiber 42, a light splitting unit 43, and a sensing unit 44.

  As shown in FIGS. 1 and 2, the condenser mirror 41 is between the electron beam irradiation device 3 and the sample W (specifically, between the objective lens L provided below the lens barrel 33 and the sample W). The cathode luminescence CL generated from the sample W is condensed and guided to the optical fiber 42. The condenser mirror 41 allows the electron beam EB converged by the lens barrel 33 to pass therethrough, and an electron beam passing hole 41a for irradiating the sample W with the electron beam EB, and an electron beam passing hole 41a. The mirror surface 41b on which the focus is set is formed. The mirror surface 41b may be a parabolic mirror or an ellipsoidal mirror, but the present embodiment uses an ellipsoidal mirror.

  The optical fiber 42 transfers the cathodoluminescence CL collected by the collecting mirror 41 to the spectroscopy unit 43. The front end surface, which is the light receiving surface of the optical fiber 42, is arranged at the focal point of the condenser mirror 41, and the rear end portion is connected to the light splitting unit 43.

  The spectroscopy unit 43 converts the cathodoluminescence CL collected by the condensing mirror 41 into a spectrum, and is configured using, for example, a monochromator.

  The sensing unit 44 is a light detection unit, which measures the intensity of each monochromatic light that has been divided into a plurality of wavelengths by the spectroscopic unit 43 for each wavelength, and obtains a current value (or a voltage value) corresponding to the intensity of each monochromatic light. ) Is output.

  The information processing device 5 is a general-purpose or dedicated computer including a CPU, a memory, an input / output interface, an AD converter, an input unit, and the like. When the CPU and its peripheral devices operate based on a program stored in a predetermined area of the memory, the information processing device 5 receives the output signal from the detection device 4, The function as the calculation unit 52 for calculating the stress and the like at each scanned measurement point is exhibited.

  However, the sample analyzer 100 of the present embodiment is configured such that a decelerating electric field for decelerating the electron beam EB toward the sample is generated between the electron beam irradiation device 3 and the condenser mirror 41.

Specifically, as shown in FIG. 1, the sample analyzer 100 includes a retarding voltage applying unit that applies a retarding voltage for decelerating the electron beam EB to the sample table 201 on which the sample W is mounted and the condenser mirror 41. 6 is further provided.
In the present embodiment, the sample W and the sample table 201 are electrically connected, and a retarding voltage is applied to the sample W via the sample table 201. A retarding voltage may be directly applied to the sample W, for example, when it is not electrically connected.

The retarding voltage applying unit 6 applies a retarding voltage of the same magnitude to the sample W and the condenser mirror 41, and specifically has a retarding power supply for applying a negative retarding voltage. I have. Here, the retarding voltage is made variable.
The retarding voltage is controlled based on the beam current of the electron beam EB or the acceleration voltage of the electron beam irradiation device 3 by, for example, the retarding voltage control unit provided in the information processing device 5 or another processing device. You.

  Here, when the retarding voltage is applied to the sample W and the light collecting mirror 41, an electric field is generated around the sample W and the light collecting mirror 41 as shown in FIG. In particular, a deceleration electric field for decelerating the electron beam EB is generated between the back surface 41c of the mirror surface 41b of the condensing mirror 41 and an opposing member facing the back surface 41c. The opposing members here are the lens barrel 33 and the objective lens L that constitute the lens mechanism of the electron beam irradiation device 3, and are grounded here. More specifically, the objective lens L includes, for example, a coil (not shown) to which a predetermined current is applied, a yoke (not shown) for accommodating the coil, and the like. A deceleration electric field is generated between the light collecting mirror 41 and the back surface 41c. The objective lens L may be an electrostatic lens type.

  In the configuration shown in FIG. 3, the electric field generated around the sample W and the condenser mirror 41 is partially distorted from the back surface 41c side of the condenser mirror 41 to the mirror surface 41b side and is distorted along the mirror surface 41b. (A part surrounded by a chain line in FIG. 3). As a result, the distorted electric field exerts a force on the electrons passing through the electron beam passage holes 41a of the condensing mirror 41, the trajectory of the electron beam EB toward the sample W is bent, and the image obtained by the electron microscope is distorted. I will.

  Therefore, as shown in FIGS. 1, 2 and 4, the sample analyzer 100 of the present embodiment includes an electrostatic lens 7 provided between the irradiation unit 3 and the condenser mirror 41, and the electrostatic lens 7 It further includes a deceleration voltage application unit 8 for applying a deceleration voltage different from the retarding voltage. Here, the deceleration voltage is made variable.

  With such a configuration, the energy of the electron beam EB, that is, the magnitude of the beam current is determined according to the acceleration voltage, the retarding voltage, and the deceleration voltage in the electron beam irradiation device 3, and by changing the retarding voltage and the deceleration voltage, The beam current of the electron beam EB applied to the sample W can be changed.

  The electrostatic lens 7 functions as an electrostatic lens with respect to the passing electron beam EB, and is formed from one or a plurality of electrodes (not shown) having an electron beam passage hole 7h through which the electron beam EB passes. It is configured. Here, each lens is arranged so that the central axis of the electrostatic lens 7 and the central axis of the objective lens L are coaxially located. More specifically, the electronic lens formed on the electrostatic lens 7 is The central axis of the line passage hole 7h and the central axis of the coil forming the objective lens L are coaxially arranged.

  The deceleration voltage application unit 8 applies a predetermined deceleration voltage to one or a plurality of electrodes forming the electrostatic lens 7. The deceleration voltage here is set so that the deceleration electric field generated between the objective lens L and the condenser mirror 41 is generated mainly between the objective lens L and the electrostatic lens 7. That is, the gradient of the deceleration electric field between the objective lens L and the electrostatic lens 7 is set to be larger than the gradient of the deceleration electric field between the electrostatic lens 7 and the condenser mirror 41, in other words, the gradient of the The deceleration voltage is set so that the potential difference between the electrostatic lens 7 and the condenser mirror 41 is larger than the potential difference between the electrostatic lens 7 and the condenser mirror 41. Thus, the electron beam EB can be focused while being decelerated.

  Here, FIG. 4 shows a result of simulating an electric field generated when a retarding voltage is applied to the electrostatic lens 7 while a retarding voltage is applied to the sample W and the condenser mirror 41. It is assumed that the objective lens is grounded, and the calculation conditions are that the energy of the electron beam EB is -2.0 V, the retarding voltage is -1.0 V, and the deceleration voltage is -1.5 V.

  As can be seen from the simulation results, by applying the deceleration voltage to the electrostatic lens 7, it is understood that the electric field that goes from the back surface 41 c of the condenser mirror 41 to the mirror surface 41 b is suppressed. As a result, the electron beam EB advances toward the sample W without bending as much as possible.

As described above, the electrostatic lens 7 of the present embodiment has the wraparound suppressing function of preventing the electric field from wrapping around from the back surface 41c of the condenser mirror 41 to the mirror surface 41b.
It is not necessary for the electrostatic lens 7 to completely suppress the electric field from flowing from the back surface 41c side to the mirror surface 41b side, and an image obtained by an electron microscope in which the sample analyzer 100 is incorporated is substantially eliminated. What is necessary is just to be able to suppress to the extent that there is no distortion.

<Effect of this embodiment>
According to the sample analyzer 100 according to the present embodiment configured as described above, the deceleration electric field is generated between the objective lens L and the condenser mirror 41, that is, on the back surface 41c side of the condenser mirror 41. Distortion of the deceleration electric field along the mirror surface 41b of the focusing mirror 41 can be suppressed without providing a member between the focusing mirror 41 and the sample W.
As a result, by applying a retarding voltage to the sample W, it is possible to decelerate the electron beam and irradiate the sample with the electron beam, and it is possible to prevent the detection efficiency of the cathode luminescence from lowering.

  Further, an electrostatic lens 7 is provided between the objective lens L and the condenser mirror 41, and a deceleration voltage is applied to the electrostatic lens 7, so that a deceleration electric field is mainly generated between the electrostatic lens 7 and the objective lens L. Since the decelerating electric field is generated in between, it is possible to more reliably suppress the deceleration electric field from wrapping around the mirror surface 41b of the focusing mirror 41.

  Also, since the same magnitude of the retarding voltage is applied to the sample W and the condensing mirror 41, no potential gradient is generated between them, and no electromagnetic force acts on the electrons. Can be guided to the sample W without bending, and image distortion can be prevented.

  In addition, since the central axis of the electrostatic lens 7 and the central axis of the objective lens L are provided coaxially, the electron beam EB can be guided to the sample W while being focused, for example, without bending its trajectory. .

<Other modified embodiments>
Note that the present invention is not limited to the above embodiment.

  For example, a retarding voltage is not necessarily required for the sample and the condensing mirror. For example, the sample and the condensing mirror may be grounded.

  Further, in the configuration shown in FIG. 3, it is not necessary to provide the electrostatic lens 7 between the objective lens L and the condenser mirror 41 if the image distortion is within the allowable range.

  Further, in the above-described embodiment, the case where the deceleration voltage (-1.5 V) applied to the electrostatic lens is smaller than the retarding voltage (-1.0 V) applied to the sample W and the condenser mirror 41 has been described. The deceleration voltage may be greater than or equal to the retarding voltage.

  In addition, the sample analyzer 100 may include a position adjustment mechanism for moving the electrostatic lens 7 along the central axis. Thereby, for example, the separation distance between the electrostatic lens 7 and the objective lens L is set, for example, to such an extent that no discharge occurs between them, or the electric-side electric field generated between the objective lens L and the condenser mirror 41 is reduced. Can be set to occur mainly between the objective lens L and the electrostatic lens 7.

In addition, it is not always necessary to use the electrostatic lens 7 as the sample analyzer 100. In order to suppress an electric field that goes from the back surface 41c side of the condenser mirror 41 to the mirror surface 41b side, as shown in FIG. A plate-like member 91 may be provided on the back surface 41c side of the mirror 41. The plate-shaped member 91 is preferably parallel to the back surface 41c of the light collecting mirror 41, and is provided here continuously and integrally with the back surface 41c of the light collecting mirror 41. However, the plate member 91 may be discontinuous with the back surface 41c of the light collecting mirror 41c, or may be separate from the light collecting mirror 41.
With such a configuration, as shown in the simulation result of FIG. 5, the electric field generated between the condenser mirror 41 and the objective lens L can be prevented from wrapping around the mirror surface 41b.
In the configuration shown in FIG. 5, there is a possibility that an electric field generated by applying a retarding voltage to the light collecting mirror 41c is drawn to the plate-like member 91. Therefore, as shown in FIG. 5, a second plate-like member 92 may be provided which is disposed closer to the sample W than the plate-like member 91 and faces the plate-like member 91. In this case, it is possible to prevent the electric field generated by the retarding voltage from being attracted to the plate member 91.

Further, the sample analyzer according to the present invention, which detects the light emitted from the sample irradiated with the charged particles and analyzes the sample, an irradiation unit that irradiates the sample with charged particles, A part is provided between the sample and the sample, and a collecting mirror for collecting light emitted from the sample, and a retarding voltage for decelerating the charged particles, the sample or the sample table on which the sample is mounted. A retarding voltage applying section to be applied, and a plate-shaped member disposed on the sample side of the converging mirror on the sample side with respect to the mirror surface without disturbing the irradiation of the charged particles. Is also good.
Even with such a configuration, the plate-shaped member can suppress the distortion of the electric field between the sample and the light-collecting mirror caused by the retarding voltage without lowering the efficiency of detecting the cathodoluminescence.

  Specifically, as shown in FIG. 6, a mode in which a flat plate-shaped member 93 is provided between the sample W and the light collecting mirror 41 is exemplified. Specifically, the plate member 93 is arranged in parallel with the sample W, and is provided below the mirror surface 41b of the condenser mirror 41 and on the reflection direction side of the mirror surface 41b. The plate-like member 93 is provided at a position that does not block the cathode luminescence generated from the sample W toward the mirror surface 41b of the focusing mirror 41, and generates an electric field due to a retarding voltage with the sample W. is there. Note that the arrangement of the plate-like member 93 may block part of the cathode luminescence toward the mirror surface 41b as long as the detection efficiency of the cathode luminescence can be ensured.

  As shown in FIG. 7, for example, a notch in a semicircular shape or a partial arc shape is provided in an end portion 93a of the plate member 93 on the side of the light collecting mirror 41. Further, a taper 93b diverging toward the sample W side is provided on the surface of the end portion 93a on the sample W side.

  FIG. 6 shows a result of simulating an electric field generated when a retarding voltage is applied to the sample W or the sample stage in the above configuration. The calculation conditions are as follows: the energy of the electron beam EB is -2.0 V, the retarding voltage is -1.0 V, the voltage of the condenser mirror 41 is 0 V, and the voltage of the plate member 91 is 0 V. From this simulation result, it is understood that the distortion of the electric field affecting the trajectory of the electron beam EB is suppressed by the plate member 93.

Further, as shown in FIG. 8, the plate-like member 93 may be provided with a through-hole 93h for passing the cathode luminescence toward the mirror surface 41b of the condenser mirror 41.
With such a configuration, as can be seen from the simulation results shown in FIG. 8, the distortion of the electric field can be further suppressed, and the bending of the electron beam can be suppressed more reliably.

  6 to 8, the plate-like member 93 may be integrated with the condenser mirror 41 or may be separate.

  In addition, when detecting light in a wavelength range that is absorbed by air, such as deep ultraviolet light, for example, as shown in FIG. 9, the detection device 4 is configured to fill the light passage region with nitrogen gas. Is also good. Specifically, the detection device 4 includes an outer tube 46 provided with a transmission window 45 such as a lens for transmitting the cathode luminescence collected by the collecting mirror 41, and an inner tube 47 provided inside the outer tube 46. Having a double tube structure. Further, the transmission window 45 and the opening 47h of the inner cylinder 47 are arranged apart from each other. With this configuration, the nitrogen gas that has flowed between the outer cylinder 46 and the inner cylinder 47 passes through the gap between the transmission window 45 and the opening 47h of the inner cylinder 47 into the inside of the inner cylinder 47 that serves as a light passage area. It can flow into the space. Note that the internal space of the inner cylinder 47 does not necessarily need to be filled with nitrogen gas, and may be reduced in pressure to a vacuum state.

  In addition, in the above-described embodiment, an electron beam is irradiated as an energy beam, but other devices such as an X-ray or an ion beam may be irradiated.

  In addition, in the above embodiment, the cathode luminescence is measured. However, for example, a photoluminescence, a Raman light, or the like may be measured.

  In addition, it goes without saying that the present invention is not limited to the above-described embodiment, but can be variously modified without departing from the gist thereof.

100 sample analyzer 2 vacuum chamber 3 electron beam irradiation device (irradiation unit)
W: sample 41: condenser mirror 6: retarding voltage application unit 7: electrostatic lens 8: deceleration voltage application unit

Claims (7)

A sample analyzer for analyzing the sample by detecting light emitted from the sample irradiated with the charged particles,
An irradiation unit that irradiates the sample with charged particles,
A light-collecting mirror that is provided between the irradiation unit and the sample and collects light emitted from the sample,
A sample analyzer configured to generate a decelerating electric field for decelerating the charged particles between the irradiation unit and the condenser mirror.   2. The sample analyzer according to claim 1, further comprising a retarding voltage applying unit that applies a retarding voltage for decelerating the charged particles to the sample or a sample stage on which the sample is mounted, and the focusing mirror. 3. . An electrostatic lens provided between the irradiation unit and the condenser mirror,
The sample analyzer according to claim 1, further comprising: a deceleration voltage application unit configured to apply a deceleration voltage for decelerating the charged particles to the electrostatic lens. The irradiation unit has an objective lens through which the charged particles pass,
The sample according to claim 3, wherein the electrostatic lens is provided between the objective lens and the condenser mirror, and a central axis of the objective lens and a central axis of the electrostatic lens are coaxial. Analysis equipment.   An electron microscope comprising the sample analyzer according to any one of claims 1 to 4. A light collecting mirror unit used in a sample analyzer for analyzing the sample by detecting light emitted from the sample irradiated with the charged particles, comprising an irradiation unit for irradiating the sample with charged particles,
A light-collecting mirror that is provided between the irradiation unit and the sample, and collects light emitted from the sample.
A converging mirror unit comprising: a retarding voltage for decelerating the charged particles; and a sample stage on which the sample or the sample is placed; and a retarding voltage applying unit for applying the retarding voltage to the converging mirror. An electrostatic lens provided between the irradiation unit and the condenser mirror, through which the charged particles pass,
The focusing mirror unit according to claim 6, further comprising: a deceleration voltage application unit that applies a deceleration voltage for decelerating the charged particles to the electrostatic lens.