KR20160056363A - Apparatus and Method for Evaluation Platform of Charged Particle Beam System - Google Patents

Abstract

The present invention relates to an evaluation platform device for measuring and evaluating the position, size, and angular current density of a virtual charged particle source to understand the characteristics of measuring and processing devices based on a charged particle beam such as an electron beam or an ion beam and to a method for evaluating a charged particle beam system. The evaluation platform device according to the present invention comprises: a chamber through which a charged particle beam discharged from a charged particle source passes; an aperture provided in the chamber and positioned in the path of the charged particle beam to limit the size of the charged particle beam; and a screen provided on one side of the chamber and positioned in the path of the charged particle beam to display an image of the charged particle beam passing through the aperture. The evaluation platform device evaluates at least one from the charged particle beam system and the charged particle source based on the image of the charged particle beam displayed on the screen. Therefore, the precise evaluation of the charged particle beam system and the charged particle source can be performed by one platform device.

Description

Technical Field [0001] The present invention relates to an evaluation platform for a charged particle beam system and a charged particle beam system evaluation method for the charged particle beam system,

The present invention relates to an evaluation platform apparatus for a charged particle beam system and a method for evaluating a charged particle beam system. More particularly, the present invention relates to a method for evaluating a charged particle beam system, The present invention relates to an evaluation platform apparatus and a charged particle beam system evaluation method for measuring and evaluating position, size, current density, and the like.

Generally, an electron beam or an ion beam used as a source of an electron microscope or an ion microscope is referred to as a charged particle beam. Such a charged particle beam is generally made by focusing charged particles in a vacuum using a magnetic lens or an electrostatic lens.

A charged particle beam system refers to a charged particle beam generating apparatus that generates a charged particle beam, a charged particle optical system that controls a charged particle beam, and a system that irradiates a charged particle beam to measure or process the charged particle beam.

SEM (Scanning Electron Microscope), which is a scanning electron microscope, and TEM (Transmission Electron Microscope), which is a transmission electron microscope, are used for measuring a sample using an electron beam. The scanning electron microscope detects secondary electrons or back scattered electrons having the highest probability of occurrence of various signals generated in the sample when the electron beam is scanned over the sample surface Observe the target sample. The transmission electron microscope observes the internal structure of the sample by causing the high-energy battery beam to pass through the sample through the electron lens system to form an image on the high-resolution image collecting device.

FIB (Focused Ion Beam), HIM (Helium Ion Microscope), SIMS (Secondary Ion Mass Spectrometer), RGA (Residual Gas Analyzer) and mass spectrometer are available for measuring / processing / analyzing samples using ion beam.

KR Patent No. 10-0345362 KR Patent Publication No. 10-2013-0113384 KR Patent No. 10-1405901 KR Patent No. 10-2014-0103879

Since such a charged particle beam system requires measurement resolution and processing accuracy of several nanometers, it is necessary to accurately evaluate the design values of the charged particle beam and the charged particle beam, which are the core components of the charged particle beam system. However, in order to evaluate a charged particle beam source or a charged particle beam optical system, it is necessary to construct a complicated structure or an evaluation system having an integrated function does not exist separately, so that critical optical factors of the charged particle beam system are compared with design values It is not easy to evaluate the results.

Accordingly, the present invention has been made to solve the above-described problems.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and an apparatus for measuring the position of a virtual source of a charged particle beam source in a charged particle beam system, measuring a current source density, measuring a virtual source size, measuring a current intensity of a probe in a charged particle beam optical system, And the evaluation of the behavior of the charged particle beam, and a method of evaluating a charged particle beam system including a charged particle beam source system or a charged particle beam source system, Beam system evaluation platform. Here, the charged particle probe can be defined as the final shape of the charged particle beam irradiated on the surface of the sample, the charged particle beam generated from the charged particle beam source being controlled by the charged particle beam optical system.

Hereinafter, specific means for achieving the object of the present invention will be described.

SUMMARY OF THE INVENTION An object of the present invention is to provide a lithographic apparatus including a chamber through which a charged particle beam emitted from a charged particle source passes; An aperture disposed in the chamber and positioned in the path of the charged particle beam to limit the size of the charged particle beam; And a screen provided at one side of the chamber and positioned in the path of the charged particle beam to form an image of the charged particle beam that has passed through the aperture and based on the image of the charged particle beam projected onto the screen Wherein the evaluation of at least one of a charged particle beam system and a charged particle source is performed.

Further comprising performing a virtual source position measurement step of measuring a virtual source position of the charged particle source and performing an evaluation of at least one of a charged particle beam system and a charged particle source based on the measured virtual source position . ≪ / RTI >

The virtual source position measuring step may be characterized by measuring a virtual source position using the following equation.

[Mathematical Expression]

Here, a _virtual is the distance from the virtual source position to the aperture, D _1apt is the aperture diameter of the aperture, D ₂ is the diameter of the charged particle beam image formed on the screen, and l ₁ is the distance from the aperture to the screen .

The virtual source position measuring step further includes a center axis moving step of moving the aperture by a specific distance in the lateral direction of the charged particle beam path to move the center axis of the charged particle beam, And the virtual source position is measured using the virtual source position.

[Mathematical Expression]

Where a _virtual is the distance from the virtual source location to the aperture, δD _1apt is the specific distance the aperture moved, δD ₂ is the center axis travel distance of the charged particle beam image on the screen, l ₁ is the distance from the aperture to the screen .

Further comprising a Faraday cup provided in the chamber and located in a path of the charged particle beam to convert the particle number information of the charged particle beam into current information, wherein the Faraday cup measures a virtual source position of the charged particle source A source position measuring step; And measuring each current density of the charged particle beam based on the measured virtual source position and the current information obtained in the Faraday cup.

Further comprising a Faraday cup provided in the chamber and located in a path of the charged particle beam to convert the particle number information of the charged particle beam into current information, wherein the Faraday cup measures a virtual source position of the charged particle source A source position measuring step; And measuring the current density of the charged particle beam using the following equation based on the measured virtual source position and the current information obtained in the Faraday cup: have.

[Mathematical Expression]

Here, D ₃ denotes the effective diameter of the Faraday cup, l ₂ denotes the distance from the virtual source position to the Faraday cup, I _beam denotes the current information measured by the Faraday cup, and I 'denotes the current density of the charged particle beam.

A virtual source position measuring step of measuring a virtual source position of the charged particle source; And a virtual source size measuring step of measuring a size of the charged particle beam virtual source using the diameter of the charged particle beam image formed on the screen based on the measured virtual source position.

A virtual source position measuring step of measuring a virtual source position of the charged particle source; And a virtual source size measuring step of measuring a size of the charged particle beam virtual source using the following equation based on the measured virtual source position.

[Mathematical Expression]

Where a _virtual is the distance from the virtual source location to the aperture, l ₁ is the distance from the aperture location to the screen, D _src is the size of the virtual source of charge, D _IMG is the distance from the edge of the charged particle beam image Means a distance ranging from 25% to 75% of the intensity of the beam (100%).

Further, the chamber may be formed by continuously stacking cylindrical members having a "a" -shaped cross section and being configured to be able to tilt, and the center axis of the charged particle beam is adjusted by the chamber.

A sample stage disposed in the chamber and positioned in the path of the charged particle beam and on which a sample to be observed is seated; And a detector provided in the chamber, for detecting electrons irradiated on the sample and reflected by the charged particle beam, or detecting a charged particle beam through which the charged particle beam is irradiated to the sample, .

Also, the inside of the chamber can be maintained at a high vacuum, an ultra-high vacuum, and a very high vacuum, and the material of the chamber is low-carbon steel having a carbon content of 0.5 wt% or less.

It is an object of the present invention to provide a method and apparatus for mounting a charged particle source on a charged particle beam system evaluation platform apparatus, And a virtual source position measurement step of measuring a virtual source position of the charged particle source, wherein, after the virtual source position measurement step, the virtual source position measurement step of measuring the virtual source position of the charged particle source based on the measured current source position and the current information obtained in the Faraday cup Each current density measuring step of measuring each current density of the charged particle beam; Or a virtual source size measuring step of measuring a size of a charged particle beam virtual source by using a diameter of an image of the charged particle beam which is formed on the screen based on the measured virtual source position, Beam system evaluation method.

As described above, the present invention has the following effects.

First, according to the embodiment of the present invention, accurate evaluation of the source and the charged particle optical system in the charged particle beam system can be performed in one platform device.

Secondly, according to the embodiment of the present invention, it is possible to collectively measure the optical source position, the current density measurement, and the virtual source size measurement, which are optical characteristics of the charged particle beam source, Evaluation is possible. "

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate preferred embodiments of the invention and, together with the description, And shall not be interpreted.
1 is a photograph of a charged particle beam system evaluation platform apparatus according to an embodiment of the present invention,
2 is a schematic diagram of a charged particle beam system evaluation platform apparatus according to an embodiment of the present invention,
FIG. 3 is a flowchart illustrating a method of evaluating a source of a charged particle beam according to an embodiment of the present invention;
4 is a schematic diagram showing the position of a charged particle source,
FIG. 5 is a schematic diagram showing a step of measuring a virtual source position in a charged particle beam system evaluation platform apparatus according to an embodiment of the present invention;
6 is a schematic diagram showing a step of moving a variable aperture in a charged particle beam system evaluation platform apparatus according to an embodiment of the present invention to measure a virtual source position,
7 is a schematic diagram showing a virtual source position according to an aperture size in a charged particle beam system evaluation platform apparatus according to an embodiment of the present invention;
8 is a schematic diagram showing a step of measuring each current density in a charged particle beam system evaluation platform apparatus according to an embodiment of the present invention,
9 is a schematic diagram showing a step of measuring a virtual source size in a charged particle beam system evaluation platform apparatus according to an embodiment of the present invention;
10 is a schematic diagram showing a virtual source image measured in a charged particle beam system evaluation platform apparatus according to an embodiment of the present invention;
11A, 11B, 11C, 11D, 11E, and 11F are schematic diagrams showing a measured virtual source image on a screen of a charged particle beam system evaluation platform apparatus according to an embodiment of the present invention,
12 is a schematic diagram showing an application example of a charged particle beam system evaluation platform apparatus according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following detailed description of the operation principle of the preferred embodiment of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may unnecessarily obscure the subject matter of the present invention.

The same reference numerals are used for portions having similar functions and functions throughout the drawings. Throughout the specification, when a part is connected to another part, it includes not only a case where it is directly connected but also a case where the other part is indirectly connected with another part in between. In addition, the inclusion of an element does not exclude other elements, but may include other elements, unless specifically stated otherwise.

A charged particle beam  System evaluation platform device

FIG. 1 is a photograph of a charged particle beam system evaluation platform apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic view of a charged particle beam system evaluation apparatus according to an embodiment of the present invention. Fig. 1 and 2, a charged particle beam system evaluation platform apparatus 1 according to an embodiment of the present invention includes a charged particle source 2, variable apertures 3, a vacuum A vacuum gauge controller (9, Vacuum gauge), a Faraday cup, a TMP (6, Turbo molecular pump), a screen (7, Phosphor screen), a cooling fan a gauge controller, a rotary pump 10, a power system 11, a digital imaging system 12, a chamber 14, and a data acquisition (DAQ).

The charged particle source (2) means a source which emits a charged particle beam, such as electrons or ions. A charged particle source 2 according to an embodiment of the present invention may be provided on one side, preferably the top side, of the charged particle beam system evaluation platform device 1 and configured to irradiate a charged particle beam onto the screen 7 have.

The variable aperture 3 means a structure in which a plurality of openings are formed so that the user can select the diameter of the aperture of the aperture through which the charged particle beam passes. With this variable aperture (3), the user can select the aperture diameter of the aperture depending on the situation. The apertures with diameters selected in the variable aperture (3) are located in the path of the charged particle beam. These apertures limit and control the size of the charged particle beam. The variable aperture 3 may be located in the path of the charged particle beam or may be located outside the path of the charged particle beam and its position controlled outside the chamber 14.

The Faraday cup 5 is provided inside the chamber 14 to measure the current density of the charged particle beam. The Faraday cup 5 is a part of the Faraday cup 5, ) Or the current of the ion (+). The Faraday cup 5 can be positioned outside the chamber 14 so as to be located in the path of the charged particle beam or outside the path of the charged particle beam.

The screen 7 may be configured at the end of the chamber 14 as an image-forming configuration of the charged particle beam emitted from the source. The image of the charged particle beam that forms on the screen 7 is converted into digital data by the imaging system 12. [

The imaging system 12 is configured on one side of the screen 7 to convert the image of the charged particle beam formed on the screen 7 into digital data.

The vacuum gauge 4 is a gauge for measuring the degree of vacuum inside the chamber 14. The inside of the chamber 14 may be constituted by a vacuum to prevent collision or interference of atmospheric molecules with the charged particle beam in the path of the charged particle beam. In order to measure the degree of vacuum, a vacuum gauge 4 is constituted, and a cold cathode ionization vacuum system or a hot cathode ionization vacuum system which can measure from a high vacuum to an ultra-high vacuum can be used.

Generally, vacuum means a state in which air and gas existing in a certain space are removed. It is impossible to have a perfect vacuum that does not exist in space, and when the pressure of gas in a certain space is lower than atmospheric pressure, it is called vacuum. Vacuum is usually vacuumed at a pressure of 1 torr at atmospheric pressure, medium vacuum at 1 torr to 10 ^-3 torr, high vacuum at 10 ^-3 torr to 10 ^-7 torr, ultrahigh vacuum at 10 ^-7 torr to 10 ^-11 torr, Below these are classified as very high vacuum. [Non-Patent Document 1]

The TMP 6 is connected to the vacuum gauge 4 to suck the gas molecules in the chamber to the vacuum gauge 4.

The vacuum gauge controller 9 is connected to the vacuum gauge 4 to control the vacuum gauge system.

The cooling fan 8 is installed on one side of the charged particle beam system evaluation platform 1 to prevent overheating of the entire charged particle beam system evaluation platform 1 such as the vacuum TMP 6.

The rotary pump 10 is a vacuum pump provided at the lower end of the chamber 14 and connected to one side of the chamber 14 to suck gas molecules inside the chamber 14 in order to constitute the chamber 14 in a vacuum. The vacuum degree of the inside of the chamber 14 can be adjusted by the rotary pump 10.

The power source 11 is a configuration for supplying power to the charged particle beam system evaluation platform device 1. [

The chamber 14 is a hollow sealing structure forming a path for moving from the charged particle source 2 to the screen 7 of the charged particle beam. A charged particle source 2, a slit 13, a variable aperture 3, a Faraday cup 5, a screen 7, various lenses, and the like can be configured in the chamber 14.

The material of the chamber 14 may comprise a soft magnetic material of permalloy, muMetal or mild steel. The external magnetic field disturbs the trajectory of the charged particle beam and degrades the performance of the charged particle beam system evaluation platform device 1. In order to prevent orbital disturbance due to an external magnetic field, a charged particle beam system evaluation platform apparatus according to an embodiment of the present invention is a plate made of a soft magnetic material for shielding an external electromagnetic field, As shown in FIG. Further, in order to allow the charged particles to travel without colliding with the gas particles, the inside of the chamber 14 is formed into a vacuum state by using the rotary pump 10. At this time, the charged particle beam system evaluation platform apparatus according to an embodiment of the present invention can make such a chamber 14 made of a soft magnetic material to simultaneously shield gas particles and external electromagnetic fields by outside air.

When manufacturing a vacuum system requiring an ultra-high vacuum environment, a great deal of effort is required in selecting and processing materials in order to reduce the gas emission rate from the material itself. Vacuum chambers of ultrahigh vacuum systems are generally made of stainless steel and in special cases made of titanium or aluminum. When the charged particle beam equipment is operated in ultra-high vacuum, a plate made of Permalloly or Mu-Metal is generally formed in a vacuum chamber made of stainless steel and the electromagnetic field is shielded do. In some cases, the ultra-high vacuum chamber may be made of permalloy or mu-metal. However, the permalloy and mu-metal are expensive materials and difficult to obtain in a desired form, so that the cost of manufacturing the chamber is several times larger than that of stainless steel.

Low-carbon steel having a carbon content of 0.5 wt% or less in carbon steels is widely used as a pipe material because of its low cost and good workability. Low carbon steel is a soft magnetic material with relative permeability of several hundreds or more, and its magnetic shielding efficiency is lower than that of permalloy or mumetal having relative permeability of several thousands or more. However, low carbon is widely used for magnetic shielding of measurement equipment sensitive to external electromagnetic fields. In the electron microscope, it is used for magnetic shielding of the barrel and a sample vacuum chamber for observing the sample with an electron beam. Low carbon steel is known to have a higher gas release rate than stainless steel. [Non-Patent Document 0001] It is not used at all for ultrahigh vacuum, and is used in low-cost vacuum equipment for thin film production.

However, as a carbon steel which can be used as a material of the chamber 14 which can be used for high vacuum, ultra-high vacuum and extremely high vacuum according to an embodiment of the present invention, a carbon steel having a carbon content of 0.5 wt% Mild steel can be used, and most low-carbon steels (mild steel or low carbon steel) are available on the market. Carbon steels having a carbon content of more than 0.5 wt% may cause gas in the carbon steel to be exhausted in ultra-high vacuum, and self-disturbance may occur.

In connection with the method of manufacturing the chamber 14 according to an embodiment of the present invention, it may include a container manufacturing step and a chemical cleaning process. In relation to the container manufacturing process, first, materials such as low-carbon steel pipe, tube, plate, etc. are bended, cut and machined, grinding, ) And the like to form a container. At this time, when machining such as cutting, it is preferable to use a water-soluble cutting oil made of a mineral and an organic material.

The completed container may undergo a chemical cleaning process suitable for the high vacuum, ultra-high vacuum, and ultra-high vacuum chambers 14.

The chemical cleaning process includes a first step of removing the organic oil, a second step of removing the mineral oil, a third step of removing the thick and contaminated surface oxide film, and a fourth step of simultaneously removing the organic matter and the inorganic contamination can do. By this step, the polishing (oxide film reforming) is performed, the surface area is reduced, and the gas emission on the surface of the low carbon steel can be minimized.

However, the third step may be omitted if the surface contamination is not severe due to proper cutting process. In order to prevent oxidation or corrosion of the carbon steel when the chemical washing process of the container is completed through the first to fourth steps, nickel or chromium plating or the like is applied to the inner and outer surfaces of the prepared container And then applying an antioxidant coating to the substrate. With such a coating, the effect of minimizing the gas emission on the low carbon steel surface is generated.

The chamber 14 according to an embodiment of the present invention is manufactured through the above container manufacturing step and the chemical washing step.

The shape of the chamber 14 may also be in the form of a bellows or a prefabricated shape continuously connected with a plurality of "a" shaped cross-section cylindrical members. When the chamber 14 is formed in a bellows shape, there is an advantage that the optical axis does not change even in an external impact. However, there is a problem that the alignment of the optical axis is difficult in the chamber itself and the price is expensive. In the case where the chamber 14 is configured as a prefabricated type in which 10 to 30 cylindrical members having a "?" -Shaped cross section are assembled and coupled, there is a problem that the optical axis may be changed by an external impact. However, There is an advantage that it can be freely configured so that the optical axis can be automatically aligned using a driving means such as an electric motor. Therefore, in the charged particle beam system evaluation platform apparatus 1 according to the embodiment of the present invention, the shape of the chamber 14 can be changed from the shape of the cylinder member having the "a" It is preferable to configure it as a prefabricated form in which 30 pieces are assembled and assembled. Further, a sealing means such as an O-ring may be further provided to seal the gap between the cylindrical members.

A charged particle beam  System evaluation method

3 is a flow chart illustrating a method for evaluating a source of a charged particle beam according to an embodiment of the present invention. 3, the method for evaluating a charged particle beam source according to an exemplary embodiment of the present invention includes a virtual source position measurement step S10, a current density measurement step S20, and a virtual source size measurement step S30 can do.

Virtual source location measurement step ( S10 )

For precise evaluation of the source and system in a charged particle beam system for the purpose of achieving the present invention, one embodiment of the present invention proposes to perform a preliminary measurement of the virtual source location.

With respect to the source position, Fig. 4 is a schematic diagram showing the position of the charged particle source. 4, the charged particle source 2 is composed of a tungsten filament or the like, and the charged particle beam is emitted from the tip of the filament (the actual source position) (The virtual source position) as the charged particle beam is emitted at a low or high position. This virtual source position varies with the accelerating voltage, and a charged particle optical system that operates correctly can not be designed without considering the virtual source position according to the accelerating voltage. Conventionally, there is no platform device for evaluating a source and a system in a charged particle beam system in consideration of a virtual source position.

5 is a schematic diagram illustrating a step of measuring a virtual source location in a charged particle beam system evaluation platform apparatus according to an embodiment of the present invention. 5, a _TF is the distance from the actual source position to the variable aperture 3, a _virtual is the distance from the virtual source position to the variable aperture 3, D _1apt is the selected diameter of the variable aperture 3, D ₂ is the diameter of the charged particle beam formed on the screen 7, l ₁ is the distance from the variable aperture 3 to the screen 7 and b is the distance from the virtual source position to the screen 7. Among the above values, a _virtual is a value to be derived, D ₂ is a value that can be measured by a screen, and the remaining variables are already known values in the process of manufacturing the charged particle beam system evaluation platform 1.

According to an embodiment of the present invention, a _virtual can be derived from the following equation.

The above equation (1) can be summarized as follows.

The above equation (2) can be summarized as follows.

According to an embodiment of the present invention, since all the remaining variables are known, a _virtual can be derived by Equation (3). This derived a _virtual makes it possible to evaluate more precise sources or systems.

However, measurement of the charged particle beam Rimed diameter (D ₂₎ on the screen (7) on the virtual source position determining step (S10) has a problem that can not be accurate, since the measurement by the imaging system 12. This is because the image of the charged particle beam is not generated discontinuously around the specific boundary on the screen 7 but the boundary of the charged particle beam that forms on the screen 7 is unclear.

In order to solve such a problem, in the charged particle beam system evaluation platform apparatus 1 according to the embodiment of the present invention, as shown in FIG. 6, the position of the opening of the variable aperture 3 is shifted by a specific length in the lateral direction We propose a method to measure the virtual source position based on the difference between the center axis of the charged particle beam trajectory and the existing center axis.

6 is a schematic diagram showing a step of moving a variable aperture in a charged particle beam system evaluation platform apparatus according to an embodiment of the present invention to measure a virtual source position. In Figure 6, by the movement of the variable aperture (3) and to be moved central axis of the charged particle beam, the aperture located in the position of δD _1apt enough, the screen (7) is presented δD _second central axes are shifted. Thus can be obtained an effect which can derive a more accurate virtual source location by applying the δD _1apt, δD ₂ in place of D _1apt, D ₂ in the equation (3). When D _1apt, D ₂ Instead δD _{1a pt,} δD ₂ is substituted in equation (3) the following equation 4 is derived.

Where δD _1apt is the center axis travel distance of the charged particle beam at the aperture and δD ₂ is the center axis travel distance of the charged particle beam image at the screen. At this time, δD _1apt is equal to the specific distance traveled by the aperture, and δD ₂ can be measured without difficulty on the screen.

At this time, the virtual source position obtained in the virtual source position measurement step S10 can be changed depending on the type of the charged particle source 2 and the acceleration voltage, but is not affected by the change in the diameter of the variable aperture 3 Do not. 7 is a schematic diagram showing a virtual source position according to aperture size in a charged particle beam system evaluation platform apparatus according to an embodiment of the present invention. As shown in FIG. 7, even if the aperture size is changed to 50 .mu.m, 100 .mu.m, or 200 .mu.m, a _virtual value is maintained substantially the same. In Fig. 7, α _i is the trajectory angle of the charged particle beam, and the table below shows how a _virtual value and α _i value vary depending on the aperture size.

Aperture size [μm] 50 100 200 a _virtual [μm] 129,175 126,797 132,036 α _i [deg.] 0.011 0.023 0.043

As shown in the above table 1, a _virtual value does not substantially change according to the aperture size, but it can be confirmed that the value of α _i is directly proportional to the aperture size. The experimental conditions in Table 1 are shown in Table 2 below.

Control input V _acc = 20,000 kV V _bias = 0.563 kV V _fil = 1.2 V Monitoring I _em = 31.621 μA Camera Lens Mag .: × 1.0 f: 8

Therefore, it can be seen that the position of the virtual source does not change under the condition that the acceleration voltage is fixed. Therefore, even if the aperture size is different, it must have the same virtual source position under the same acceleration conditions. In one embodiment of the present invention, measurements with different aperture sizes under the same accelerating voltage conditions show that the same virtual source position is obtained, which is accurate. If the measurement deviation of the position of the virtual source obtained by the above method becomes large, the source to be evaluated may be evaluated as unstable. Therefore, according to the embodiment of the present invention, the stability of the source can be evaluated by using the virtual source position information under the condition that the acceleration voltage is fixed.

Therefore, the virtual source position obtained in the virtual source position measurement step S10 according to the embodiment of the present invention can be applied regardless of the aperture size.

When the virtual source position is determined as described above, each current density can be measured more accurately, or the size of the source can be measured.

Each current density  Measuring step ( S20 )

For precise evaluation of the source and system in a charged particle beam system, which is an object to achieve in the present invention, one embodiment of the present invention proposes to measure each current density after measurement of the virtual source location. 8 is a schematic diagram showing a step of measuring each current density in a charged particle beam system evaluation platform apparatus according to an embodiment of the present invention. As shown in FIG. 8, the Faraday cup 5 provided in the charged particle beam system evaluation platform 1 according to an embodiment of the present invention can be inserted into the trajectory of the charged particle beam to measure each current density .

The Faraday cup 5 according to an embodiment of the present invention is provided inside the chamber 14 to measure each current density of the charged particle beam. After the charged particle beam enters the inside of the Faraday cup, (-) or ions (+) generated while colliding with the electron beam. The faraday cup 5 can be controlled outside the chamber 14 to be located in the path of the charged particle beam or outside the path of the charged particle beam.

The Faraday cup (5) converts the charged particle into an electrical signal, which is measured directly by the measuring circuit or measuring device.

8, D ₃ is the effective diameter of the Faraday cup 5, l ₂ is the distance from the virtual source position to the Faraday cup 5, l ₃ is the distance from the variable aperture 3 to the Faraday cup 5, α _i is the trajectory angle of the charged particle beam, and I _beam is the electrical signal converted by the Faraday cup 5.

According to an embodiment of the present invention, each current density I 'can be derived by the following equation.

? _I is derived from the above equation (5) and the known values D ₃ and I ₂ .

I ', which is an angular current density, is derived from Equation (6).

When the precise current density of the source and the probe current by the optical system are measured by the virtual source position measuring step S10 and each current density measuring step S20, the loss rate of the optical system is evaluated, It is possible to precisely evaluate whether or not a sufficient amount of current to be lost is present, evaluation of a charged particle source 2, and column loss evaluation.

According to an embodiment of the present invention, the stability of the source can be evaluated by continuously measuring each current density under the condition that the acceleration voltage is fixed for a predetermined period of time.

Virtual source size measurement step ( S30 )

For precise evaluation of the source and system in a charged particle beam system, which is an object to achieve in the present invention, an embodiment of the present invention proposes to measure the virtual source size after measurement of the virtual source location. It is also possible to measure the virtual source size, or measure the virtual source size after measuring each current density.

FIG. 9 is a schematic diagram showing a step of measuring a virtual source size in a charged particle beam system evaluation platform apparatus according to an embodiment of the present invention, and FIG. 10 is a flowchart illustrating a method of estimating a virtual source size in a charged particle beam system evaluation platform apparatus according to an embodiment of the present invention FIG. 7 is a schematic diagram showing a measured virtual source image. FIG. As shown in FIG. 9, when the image of the charged particle beam is formed on the screen 7, the imaging system 12 obtains information as shown in FIG.

Conventionally, an inaccurate method such as deriving the size of a source through a knife edge method has been used. In the present invention, the effect of the knife edge is used instead of the effect of the edge edge, and the Faraday cup, which measures the current value according to the position of the knife edge, Instead, by observing the shape of the charged particle beam projected on the fluorescent plate by the effect of the aperture edge with the imaging system, the size of the charged particle source or the size of the probe by the charged particle beam optical system can be easily measured .

Therefore, in the virtual source size measuring step S30 according to the embodiment of the present invention, a method of accurately and simply deriving the virtual source size through the following proportional expression (7) is proposed.

Where D _src is the size of the charged particle virtual source and D _IMG is the distance between 25% and 75% of the maximum beam intensity (100%) in the beam intensity curve along the distance from the center in the image of the charged particle beam projected onto the screen . l ₁ is the distance from the aperture position to the screen, and a _virtual is the distance from the virtual source position to the aperture. D _IMG is clearly described in the upper graph of FIG. 10, and according to Equation (7), an effect of easily deriving the size of the charged particle virtual source can be obtained. The bottom particle beam in the charged particle gun has a certain divergence angle because it passes through the aperture with a certain diameter. As this charged particle beam passes through the aperture, a Knife-edge effect appears at the aperture edge. Therefore, by calculating the length from 25% to 75% of the maximum intensity of the charged particle beam on the fluorescent plate by multiplying the reciprocal of the magnification ratio, the size of the virtual source can be obtained. According to the virtual source size measuring step S30 according to the embodiment of the present invention, it is possible to measure the virtual source size even if the image of the charged particle beam is not concentric, and it is possible to measure the virtual source size even if it is not perfectly aligned Effect is generated.

If the size of the virtual source of the charged particle is determined by the virtual source size measuring step S30 according to the embodiment of the present invention, it is possible to accurately obtain the enlargement / reduction ratio of the optical system, so that the optical system can be designed easily, Effect can be generated.

In addition, easy access to the image through the imaging system 12 and how varying the characteristics of the beam by the variable V _bias, according to a charged particle beam systems evaluate the platform unit 1 according to an embodiment of the present invention, charged particle source (2) An effect that can be confirmed is generated. In the past, there has been no case where images of the characteristics and alignment of the charged particle beam are confirmed by an image. 11A, 11B, 11C, 11D, 11E, and 11F are schematic diagrams showing source images measured on a screen of a charged particle beam system evaluation platform apparatus according to an embodiment of the present invention. As shown in FIGS. 11A, 11B, 11C, 11D, 11E, and 11F, it can be seen that the larger the V _bias , the larger the diameter of the charged particle beam, and the degree of alignment of the charged particle beam can be confirmed visually.

The experimental conditions of the embodiment shown in Figs. 11A, 11B, 11C, 11D, 11E and 11F are as follows.

Control input V _acc = 20,000 kV V _bias  = 0.0 to 1.0 kV V _fil = 1.2 V Monitoring I _em = 31.621 μA Pressure ^{4.2 x 10 -7 → 5.4 x 10} -7 [torr] RT = 22.57 DEG C
RH = 59.57%

If there is a problem in the alignment of the charged particle beam in the imaging system 12, the image of the charged particle beam appears as an oval. In such a case, the chamber 14 of the charged particle beam system evaluation platform 1 according to the embodiment of the present invention may be constituted by a "?" Shaped cylindrical member so that the optical axis can be adjusted.

(1) derive an optical axis correction coefficient (correction information for aligning the optical axis) from the viewpoint of the charged particle optical system through the shape and characteristics of the image formed on the screen of the imaging system 12 according to the embodiment of the present invention, (Observation of the intensity of the charged particle beam indirectly) according to the condition (applied voltage) of the beam optical system, (3) the respective components (the aligner, the boiling point compensator (stigmator), the beam blanker, Lens) can be checked.

A charged particle beam  Application example of system evaluation platform device

12 is a schematic diagram showing an application example of a charged particle beam system evaluation platform apparatus according to an embodiment of the present invention, in relation to an application example of a charged particle beam system evaluation platform apparatus. As shown in FIG. 12, the charged particle beam system evaluation platform apparatus 1 according to an embodiment of the present invention is used for evaluating stability of sources of various microscopes, electrostatic column evaluation of ion microscopes, mass spectrometer ), Evaluation of electron / ion gun, electromagnetic lens of an electron microscope, and mass transfer evaluation of a quadrupole type mass filter.

The charged particle beam system evaluation platform apparatus 1 according to an embodiment of the present invention may also be constructed using a detector 16 and a sample stage 15 in a chamber 14 so that the sample stage 15 can be immediately used by a microscope . In such a case, since the resolution test can be performed in advance, the microscope becomes compact.

As described above, those skilled in the art will appreciate that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention.

1: Charger beam system evaluation platform device
2: charged particle source
3: Variable Aperture
4: Vacuum gauge
5: Faraday Cup
6: TMP
7: Screen
8: Cooling fan
9: Vacuum Gauging Controller
10: Rotary pump
11: Power supply
12: Imaging system
13: slit
14: chamber
15: sample stage
16: Detector

Claims (12)

A chamber through which the charged particle beam emitted from the charged particle source passes;
An aperture disposed in the chamber and positioned in the path of the charged particle beam to limit the size of the charged particle beam; And
A screen provided at one side of the chamber and positioned in the path of the charged particle beam to form an image of the charged particle beam that has passed through the aperture;
/ RTI >
Wherein the evaluation of at least one of a charged particle beam system and a charged particle source is performed based on the image of the charged particle beam that is incident on the screen.
The method according to claim 1,
A virtual source position measurement step of measuring a virtual source position of the charged particle source,
And evaluates at least one of a charged particle beam system and a charged particle source based on the measured virtual source position.
3. The method of claim 2,
Wherein the virtual source position measuring step measures a virtual source position using the following equation: < EMI ID =
[Mathematical Expression]

Here, a _virtual is the distance from the virtual source position to the aperture, D _1apt is the aperture diameter of the aperture, D ₂ is the diameter of the charged particle beam image formed on the screen, and l ₁ is the distance from the aperture to the screen .
3. The method of claim 2,
Wherein the virtual source location measurement step comprises:
And a center axis moving step of moving the aperture by a specific distance in the transverse direction of the charged particle beam path to move the center axis of the charged particle beam,
Wherein the virtual source position is measured using the following equation: < EMI ID =
[Mathematical Expression]

Where a _virtual is the distance from the virtual source location to the aperture, δD _1apt is the specific distance the aperture moved, δD ₂ is the center axis travel distance of the charged particle beam image on the screen, l ₁ is the distance from the aperture to the screen .
The method according to claim 1,
A Faraday cup provided in the chamber and positioned in the path of the charged particle beam to convert the particle number information of the charged particle beam into current information;
Further comprising:
A virtual source position measuring step of measuring a virtual source position of the charged particle source; And
Measuring each current density of the charged particle beam on the basis of the measured virtual source position and the current information obtained in the Faraday cup;
Is performed on the basis of the position information of the charged particle beam.
The method according to claim 1,
A Faraday cup provided in the chamber and positioned in the path of the charged particle beam to convert the particle number information of the charged particle beam into current information;
Further comprising:
A virtual source position measuring step of measuring a virtual source position of the charged particle source; And
Measuring each current density of the charged particle beam using the following equation based on the measured virtual source position and the current information obtained in the Faraday cup;
Wherein the load balancing system comprises:
[Mathematical Expression]

Here, D ₃ denotes the effective diameter of the Faraday cup, l ₂ denotes the distance from the virtual source position to the Faraday cup, I _beam denotes the current information measured by the Faraday cup, and I 'denotes the current density of the charged particle beam.
The method according to claim 1,
A virtual source position measuring step of measuring a virtual source position of the charged particle source; And
A virtual source size measuring step of measuring a size of a charged particle beam virtual source using a diameter of an image of the charged particle beam formed on the screen based on the measured virtual source position;
Is performed on the basis of the position information of the charged particle beam.
The method according to claim 1,
A virtual source position measuring step of measuring a virtual source position of the charged particle source; And
Measuring a size of a charged particle beam virtual source using the following equation based on the measured virtual source position;
Wherein the load balancing system comprises:
[Mathematical Expression]

Where a _virtual is the distance from the virtual source location to the aperture, l ₁ is the distance from the aperture location to the screen, D _src is the size of the virtual source of charge, D _IMG is the distance from the edge of the charged particle beam image Means a distance ranging from 25% to 75% of the intensity of the beam (100%).
The method according to claim 1,
Wherein the chamber is formed by continuously stacking cylindrical members having a "a" -shaped cross section, and is configured to be capable of tilting,
And a center axis of the charged particle beam is adjusted by the chamber.
The method according to claim 1,
A sample stage which is provided in the chamber and is positioned in a path of the charged particle beam and on which a sample to be observed is seated; And
A detector which is provided in the chamber and detects electrons irradiated to the sample by the charged particle beam to be reflected and detects a charged particle beam through which the charged particle beam is irradiated to the sample;
Further comprising a beam splitter for splitting the charged particle beam into two or more beams.
The method according to claim 1,
The interior of the chamber can be maintained at high vacuum, ultra-high vacuum, very high vacuum,
Wherein the material of the chamber is a low-carbon steel having a carbon content of 0.5 wt% or less.
A source mounting step of mounting a charged particle source on a charged particle beam system evaluation platform apparatus according to claim 5; And
A virtual source position measuring step of measuring a virtual source position of the charged particle source;
Lt; / RTI >
After the step of measuring the virtual source position,
Measuring each current density of the charged particle beam on the basis of the measured virtual source position and the current information obtained in the Faraday cup; or
A virtual source size measuring step of measuring a size of a charged particle beam virtual source using a diameter of an image of the charged particle beam formed on the screen based on the measured virtual source position;
Further comprising the steps of:

Images