TWI440064B - Scanning electron microscope having secondary electron detecting function - Google Patents

Description

Scanning electron microscope with reflected electron detection

The present invention relates to a scanning electron microscope having a function of detecting reflected electrons. In more detail, the present invention relates to a reflected electron using a Wien filter for separating and detecting electrons emitted from a sample into secondary electrons and reflected electrons. Scanning electron microscope for detection function.

Recently, it has not only been the minimization trend of information instruments, but also the field of cutting-edge materials is due to the industrialization of extremely fine technology, and it is necessary to provide information on the microstructure of fine structures or materials. In particular, since the second half of the 1990s, the world's research on nanometers has been active, and various studies have been carried out to identify the structure and properties of nanomaterials, and electron microscopy plays an important role.

In recent years, a scanning electron microscope has been widely used. The microscope scans the surface of a sample placed in a vacuum in a two-dimensional direction with a fine electron beam of about 1 to 100 nm, and detects a secondary occurrence on the surface of the sample. An electronic signal is displayed or recorded on a cathode conduit and a screen to analyze the fine structure of the sample shape.

Figure 1 is a diagram showing a conventional scanning electron microscope. As shown in FIG. 1, a conventional scanning electron microscope (10) includes: a light source (11) for scanning a primary electron (pe) in a vacuum gun chamber; an objective lens for secondary electrons (se) emitted from the sample; A secondary electron (se) detector (12) emitted from the surface of the sample (S).

However, due to the interaction of the original electron (pe) and the incident depth of the sample (S), a variety of forms of electrons are emitted, and by detecting various forms of electrons radiated from the sample, it is possible to detect various characteristics of the sample, but utilize In the conventional scanning electron microscope (10), only secondary electrons (se) are used as detection targets, and other electrons emitted from the sample cannot be detected.

The present invention has been made in view of the above problems, and an object thereof is to provide a scanning electron microscope having a reflection electron detecting function for separating and detecting secondary electrons and reflected electrons by using a Wien filter.

In order to achieve the above object, the present invention provides a scanning electron microscope having a reflected electron detecting function. The present invention includes a scanning electron microscope that reflects an electron detecting function, and a primary electron generated from a light source is incident on a sample, and detects a radioactive electron emitted from the sample after the incident of the original electron, and includes: a filter portion disposed between the light source and the sample, and generating a magnetic field and an electric field to separate the emitted electrons into secondary electrons (Backcontained Electron) and reflected electrons (Back Scattered Electron); and a detecting portion, Secondary electrons and reflected electrons separated by the Wien filter are separately detected.

Moreover, the detecting portion may include: a first detecting portion disposed on an upper side of the Wien filter portion for detecting the secondary electrons; and a second detecting portion configured to be in the first detecting portion Between the portion and the light source for detecting the reflected electrons. Further, one surface of the second electron incident side end portion of the first detecting portion or one surface of the second detecting portion of the reflected electron incident side end portion may form a slope.

Moreover, an angle formed by the secondary electron incident side end portion of the first detecting portion and the ground may be larger than an angle formed by the incident electron incident side end portion of the second detecting portion and the ground. Further, the detecting unit may further include the first detection from the second detection unit to guide the secondary electrons to the first detection unit side or to guide the reflected electrons to the second detection unit side. The portion of the second detecting portion is isolated from the electron guiding member disposed at a predetermined pitch.

Further, the detecting unit may further include a guiding preventing member disposed on the moving path of the reflected electrons in order to prevent the reflected electrons from being guided by the electron guiding member to the first detecting portion side. Moreover, a lens barrel may be further included for accommodating the light source, the Wien filter portion, and the detecting portion, and the end side from which the original electrons scanned by the light source are emitted is isolated in a vacuum state.

According to the present invention, there is provided a scanning electron microscope including a reflected electron detecting function, which is capable of easily separating secondary electrons and reflected electrons emitted from a sample by a Wien filter unit and detecting the respective. Moreover, secondary electrons and reflected electrons can be easily separated using a Wien filter without the need for an additional structure. Moreover, it is possible to simultaneously detect secondary electrons and reflected electrons to simultaneously understand the surface characteristics and internal characteristics of the sample. Further, by arranging the detecting portion for detecting secondary electrons and reflected electrons in the lens barrel, the overall structure can be made compact. Further, the electron incident end surface of the detecting portion is obliquely disposed so that electrons are incident perpendicularly, whereby the electron incidence rate and the measurement precision of the sample characteristics can be improved.

It is to be noted that in the following embodiments, structural elements having the same structure are collectively described in the first embodiment with the same reference numerals, and only the differences are explained in the remaining embodiments. The structure of the first embodiment. Hereinafter, a scanning electron microscope having a reflected electron detecting function according to a first embodiment of the present invention will be described in detail with reference to the accompanying drawings.

2 is a schematic cross-sectional view showing a scanning electron microscope having a reflected electron detecting function according to the first embodiment of the present invention. As shown in FIG. 2, the scanning electron microscope (100) having the reflected electron detecting function of the present invention includes a lens barrel (110), a light source (120), a converging lens (130), an aperture (140), a detecting portion (150), Wien filter section (160), objective lens (170) and sample holder (180).

The lens barrel (110) is for accommodating a light source (120), a condenser lens (130), a diaphragm (140), a detecting portion (150), a Wien filter portion (160), and an objective lens (170), which will be described later, in a housing. The inner exterior material, in which the end of the primary electron (Primary Electron: pe) injection side, that is, the end of the sample holder (180) side for arranging the sample (S), maintains a vacuum state.

The light source (120) is a member for scanning the original electron (pe) generated by heating the cathode in the lens barrel (110) downward on the side of the sample holder (180) on which the sample (S) is attached. The converging lens (130) is a member for converging original electrons (pe) emitted from the light source (120) into one point. The aperture (140) is a member for forming a primary electron (pe) condensed by the condensing lens (130) to have a certain wavelength.

The detecting unit (150) is for detecting a secondary electron (Secondary Electron: se) and a reflected electron (Back Scattered Electron: bse) emitted from the sample (S) after the incident of the original electron (pe) (ee) (ee) A component comprising a first detecting portion (151) and a second detecting portion (152).

The first detecting portion (151) is for detecting only secondary electrons (se) in the emitted electrons (ee) emitted from the sample (S), which are disposed in the light source (120) and a Wien filter (described later) ( 160) between. Since the secondary electrons (se) are laterally biased and incident on the first detecting portion (151) while moving upward from the sample (S), the first detecting portion (151) is provided in order to enable the secondary electrons to be incident perpendicularly. The end face is made into a slope.

The second detecting portion (152) is configured to detect only reflected electrons (be) in the emitted electrons (ee) emitted from the sample (S), which are disposed between the light source (120) and the first detecting portion (151), That is, it is disposed on the upper side of the first detecting unit (151). Further, the end surface of the second detecting portion (152) is also formed as a slope as in the first detecting portion (151), and since the degree of offset of the reflected electrons (be) is smaller than that of the secondary electrons (se), the second The inclination angle of the end surface of the detecting portion is preferably smaller than the inclination angle of the end surface of the first detecting portion (151).

That is, the angle (θ1) formed by the incident surface of the secondary electron (se) in the first detecting portion (151) and the ground is preferably larger than the incident surface and the ground of the reflected electron (be) in the second detecting portion (152). The angle formed (θ2) is large.

The Wien filter portion (160) is disposed between the first detecting portion (151) and the sample holder (180), that is, disposed on the lower side of the first detecting portion (151), and is emitted from the sample (S). The moving path of the emitted electrons (ee) is biased toward the detecting unit (150) side. At the same time, the Wien filter portion (160) functions to utilize the difference in the moving speeds of the secondary electrons (se) and the reflected electrons (be) included in the emitted electrons (ee) emitted from the sample (S). Physically separate the effects of secondary electrons (se) and reflected electrons (be). That is, the Wien filter unit (160) generates mutually perpendicular electric and magnetic fields on a plane perpendicular to the moving direction of the emitted electrons (ee) emitted from the sample (S) to make secondary electrons (se) and reflected electrons. (be) The movement track is offset.

The objective lens (170) is a member for focusing the focus of the original electron (pe) which is generated from the light source (120) and moved downward, on the surface of the sample (S). The sample holder (80) is disposed below the lens barrel and is a member for supporting the sample (S). In addition, the sample holder (180) is movable in the three-axis direction, and can be controlled to easily observe the sample (S) by rotation, tilting, or the like. Next, the operation of an embodiment of the above-described scanning electron microscope (100) having a reflected electron detecting function will be described in detail.

Fig. 3 is a view showing the operation of the primary electrons passing through the Wien filter unit in the scanning electron microscope having the reflected electron detecting function shown in Fig. 2; Fig. 4 is a view showing the movement trajectory of the emitted electrons emitted from the sample in the scanning electron microscope having the reflected electron detecting function shown in Fig. 2. Fig. 5 is a view showing an operation of emitting electrons passing through a Wien filter unit in a scanning electron microscope having a reflected electron detecting function shown in Fig. 2;

First, as shown in FIG. 2, the original electron (pe) generated from the light source (120) in the lens barrel (110) is accelerated by applying a high voltage, thereby being swept downward to the sample holder (S) mounted sample holder (180) )side. However, at this time, the scanning direction of the original electron (pe) is controlled by a predetermined reflector (not shown) in the lens barrel (110).

The original electron (pe) scanned from the light source (120) passes through the converging lens (130) and the aperture (140), and then reaches the Wien filter portion (160). At this time, a magnetic field and an electric field are generated in a direction perpendicular to each other on a predetermined surface of the Wien filter portion (160) parallel to the ground.

The force applied to the original electrons through the electric field generated by the Wien filter portion (160) is explained. As shown in Fig. 3(a), when the original electron (pe) moving downward passes through the Wien filter unit (160), the +x axis is transmitted through the electric field (20) generated by the Wien filter unit (160). The power of direction.

At the same time, as shown in (b) of FIG. 3, which is applied to the original electron by the magnetic field (30) generated by the Wien filter unit (160), the original electron (pe) and the filter are filtered by Wien. The magnetic field (30) generated by the device (160) acts and receives the force in the -x-axis direction according to Fleming's left-hand law.

At this time, the Wien filter portion (160) is controlled such that the original electron (pe) receives the same force from the electric field (20) and the absolute value of the force received by the magnetic field (30). Therefore, the force applied to the original electron (pe) by the magnetic field (30) of the Wien filter portion (160) is applied to the electric field of the original electron (pe) by the electric field of the Wien filter portion (160) (20) The force cancels and moves vertically downward (-z direction) without biasing one side in the xy plane.

The original electron (pe) passing through the Wien filter unit (160) is moved vertically downward (in the -z-axis direction) through the above process, and finally the sample (S) is injected. At this time, the primary electrons (pe) injected into the sample (S) respectively exhibit different mechanisms according to the depth on the surface of the sample (S), and emit electrons of different forms according to the depth of the sample (S).

For example, when the original electron (pe) is incident on the surface of the sample (S) and reacts with the surface to emit secondary electrons (se), and the original electron (pe) is incident deeper from the surface of the sample (S), the radiation is emitted. Reflective electrons (be). Further, after the original electron (pe) is incident, x-ray or the like is emitted from the sample (S).

However, it is assumed in the present embodiment that the emitted electrons (ee) emitted from the sample (S) after the incident of the original electron (pe) include only the secondary electrons (se) and the sample emitted from the surface of the sample (S). The reflected electrons (be) which are incident on the surface of (S) and are emitted deeper are described.

As shown in FIG. 4, if the emitted electrons (ee) divided into secondary electrons (se) and reflected electrons (be) are vertically emitted from the sample (S) to the upper side (+Z-axis direction), these radioactive electrons (ee) Before moving through the Wien filter portion (160), it moves along the same path as the scanning path of the original electron (pe).

When the emitted electrons (ee) emitted from the sample (S) reach the Wien filter portion (160), the electric field in the same direction as that generated from the Wien filter portion (160) when the original electron (pe) is swept downward (20) and the magnetic field (30) are applied to the radioactive electrons (ee).

Next, the force applied to the radioactive electrons (ee) by the electric field (20) and the magnetic field (30) generated by the Wien filter unit (160) will be described in detail. First, as shown in (a) of FIG. 5, the force applied to the emitted electrons (ee) by the electric field generated by the Wien filter unit (160), the sample (S) is upward (+z-axis direction). The vertically moving electrons (ee) are subjected to the +x-axis force by the electric field (20).

Further, as shown in (b) of FIG. 5, which is applied to the force of the radioactive electrons (ee) by the magnetic field (30) generated by the Wien filter unit (160), the force generated by the action of the magnetic field (30) is shown. And formed in the opposite direction to the above-described force applied to the original electron (pe), that is, in the +x-axis direction. That is, since the emitted electrons are applied with the same force as the force applied to the emitted electrons (ee) by the electric field (20), the moving trajectory of the emitted electrons (ee) is biased toward the position where the detecting portion (150) is provided. That is to say, the emitted electrons (ee) move in the opposite direction to the original electron (pe), and are simultaneously biased to one side by the force generated by the action of the magnetic field (30) and the force applied by the electric field (20).

At this time, the velocity of the reflected electron (be) contained in the emitted electrons (ee) is greater than the velocity of the secondary electron (se), but the moving trajectory of the secondary electron (se) which is relatively slow in speed due to the same force is compared The moving trajectory of the reflected electron (be) is bent at a larger angle, and the moving trajectory of the relatively faster reflected electron (be) is bent at a smaller angle. Due to the speed difference between the electrons, the electrons (ee) passing through the Wien filter portion (160) are separated into secondary electrons (se) biased at a relatively sharp angle and reflected electrons biased at a slow angle ( Be).

The secondary electrons (se) separated from the emitted electrons (ee) emitted from the sample (S) and relatively sharply biased are incident on the first detecting portion (151) disposed on the upper side of the Wien filter portion (160), On the other hand, the reflected electrons (be) which are separated by the relatively slow angular offset and are incident on the second detecting portion (152) disposed on the upper side of the first detecting portion (151).

On the other hand, in the front end portion of the first detecting portion (151) and the second detecting portion (152), a surface on which electrons are incident forms a slope, so that secondary electrons (se) and reflected electrons (be) are vertically incident first. The end faces of the detecting portion (151) and the second detecting portion (152) are used to increase the incident rate. Further, the surface of the first detecting portion (151) where the secondary electron (se) is incident and the surface of the second detecting portion (152) where the reflected electron (bse) is incident are formed at different angles, thereby enabling each electron to be made Normal incidence to increase the electron incidence. Next, a scanning electron microscope having a detection function according to a second embodiment of the present invention will be described in detail.

Fig. 6 is a schematic cross-sectional view showing a scanning electron microscope having a detection function according to a second embodiment of the present invention. As shown in FIG. 6, a scanning electron microscope (200) having a detection function according to a second embodiment of the present invention includes a lens barrel (110), a light source (120), a converging lens (130), an aperture (140), and detection. Part (250), Wien filter unit (160), objective lens (170) and sample holder (180). The lens barrel (110), the light source (120), the converging lens (130), the aperture (140), the detecting portion (250), the Wien filter portion (160), the objective lens (170), and the sample holder (180) of the present embodiment. The structure is the same as that of the first embodiment described above, and the repetitive description is omitted.

The detecting portion (250) includes a first detecting portion (251), a second detecting portion (252), an electron guiding member (251a, 252a), and a guiding preventing member (253). The first detecting portion (251) is a member that selectively detects only secondary electrons (se). On the other hand, an electron inducing member (251a) for forming a field is disposed on an end portion of the first detecting portion (251) to induce secondary electrons passing through the Wien filter portion (160) to the first detecting portion. (251) Side movement.

The second detecting portion (252) is a member that selectively detects only reflected electrons (bse). An electron inducing member (252a) for forming a field is disposed on an end of the second detecting portion (252) to induce reflected electrons (bse) passing through the Wien filter portion (160) to the second detecting portion (252). ) Side movement.

The guide preventing member (253) is for preventing the reflected electrons (bse) passing through the Wien filter portion (160) from being passed to the first detecting portion by the electron guiding member (251a) of the first detecting portion (251) (251) A side moving member having a through portion formed in a path of reflected electrons (bse) and maintained in a grounded state to prevent reflected electrons (bse) from being directed to the first detecting portion (251) side.

The present invention is not limited to the above-described embodiments and modifications, and can be embodied in various forms within the scope of the claims. It is within the scope of the present invention to have a range in which the ordinary knowledge can be deformed in the field of the present invention without departing from the scope of the present invention as claimed in the scope of the present invention. .

100‧‧‧ scanning electron microscope

110‧‧‧Mirror tube

120‧‧‧Light source

130‧‧‧ Converging lens

140‧‧‧ aperture

150‧‧‧Detection Department

151‧‧‧First Inspection Department

152‧‧‧Second Detection Department

160‧‧‧Wien Filter Department

170‧‧‧ objective lens

180‧‧‧sample holder

Fig. 1 is a view showing a conventional scanning electron microscope.

Fig. 2 is a schematic cross-sectional view showing a scanning electron microscope having a reflected electron detecting function according to a first embodiment of the present invention.

Fig. 3 is a view showing the operation of the primary electrons passing through the Wien filter unit in the scanning electron microscope having the reflected electron detecting function shown in Fig. 2 .

Fig. 4 is a view showing the movement trajectory of the emitted electrons emitted from the sample in the scanning electron microscope having the reflected electron detecting function shown in Fig. 2.

Fig. 5 is a view showing an operation of emitting electrons passing through a Wien filter unit in a scanning electron microscope having a reflected electron detecting function shown in Fig. 2 .

Fig. 6 is a schematic cross-sectional view showing a scanning electron microscope having a reflected electron detecting function according to a second embodiment of the present invention.

100. . . scanning electron microscope

110. . . Lens barrel

120. . . light source

130. . . Converging lens

140. . . aperture

150. . . Detection department

151. . . First detection unit

152. . . Second detection unit

160. . . Wien Filter Division

170. . . Objective lens

180. . . Sample holder

S. . . sample

Pe. . . Original electron

Claims (5)

A scanning electron microscope having a reflected electron detecting function, injects a primary electron generated from a light source into a sample, and detects a radioactive electron emitted from the sample after the incident of the original electron, wherein: Wien filtering a portion between the light source and the sample, generating a magnetic field and an electric field to separate the emitted electrons into secondary electrons (Second Electro Electron) and a reflection electron (Back Scattered Electron); and a detecting portion for respectively detecting The secondary electrons and the reflected electrons separated from the Wien filter include: a first detecting portion disposed on an upper side of the Wien filter portion for detecting the secondary electron; and a second detecting portion, Arranging between the first detecting portion and the light source for detecting the reflected electrons; wherein the detecting portion is for guiding the secondary electrons to the first detecting portion side, or The reflected electrons are guided to the second detecting portion side, and further include an electron guiding member that is disposed at a constant pitch from an end portion of the first detecting portion or the second detecting portion. A scanning electron microscope having a reflected electron detecting function according to the first aspect of the invention, wherein the first detecting portion is in the end surface of the secondary electron incident side or the second detecting portion The end face of the incident side of the reflected electron forms a slope. A scanning electron microscope having a reflected electron detecting function according to claim 2, wherein the first detecting portion is two The angle formed by the secondary electron incident side end portion and the ground surface is larger than the angle formed by the reflected electron incident side end portion and the ground in the second detecting portion. A scanning electron microscope having a reflected electron detecting function according to the first aspect of the invention, wherein the detecting unit further includes a detecting unit for preventing the reflected electrons from being guided by the electron guiding member to the first detecting unit side. A guiding preventing member disposed on a moving path of the reflected electrons. A scanning electron microscope having a reflected electron detecting function according to any one of claims 1 to 4, further comprising: a lens barrel for accommodating the light source, the Wien filter portion, and the The detecting portion is provided with the end portion side from which the primary electrons scanned from the light source are emitted is isolated in a vacuum state.