KR101761227B1 - Method of blanking a particle beam in a particl beam column - Google Patents

Abstract

The present invention relates to a method for blanking a particle beam in a particle beam column, and more particularly to a method for preventing a particle beam from being scanned toward a sample in a particle beam column. The present invention is best utilized in a low energy microparticle beam column by performing blanking by applying a blanking voltage to an electrode of a positive potential electron lens in a conventional particle beam column.

Description

[0001] The present invention relates to a method of blanking a particle beam in a particle beam column,

The present invention relates to a method for blanking a particle beam in a particle beam column, and more particularly to a method for preventing a particle beam from being scanned toward a sample in a particle beam column.

The particle beam column is composed of a particle source (emission source) and electron lenses that are operated by an electrostatic field or a magnetic field to generate and scan a particle beam, typically an electron column or an ion beam column. Such an electron column can be used for an inspection apparatus using an electron microscope, a semiconductor lithography, or an electron beam, for example, inspection of via holes / contact holes of a semiconductor device, surface inspection and analysis of a sample, - It is used for the inspection of abnormalities of TFT (Thin Film Transistor) in the LCD device.

The electron column is a representative example of a particle beam column. As an example of an electron column for generating and scanning an electron beam, a microcolumn is an electron emission source which operates under the basic principle of a scanning tunneling microscope (STM), and a microelectronic column based on an electro- It was first introduced. The microelectronic column can be used in a multi-type electron column structure of parallel or series structure by arranging several small structures to form an improved electron column by finely assembling fine parts to minimize optical aberration. For this purpose, the aperture of the lens is made into a membrane by an etching process and used as an electrostatic lens to make a lens from a silicon wafer using a semiconductor process.

Fig. 1 is a diagram showing the structure of a micro-electron column, in which an electron emission source, a source lens, a deflector, and an Einzel lens are aligned and an electron beam is scanned.

Typically, a microcolumn is a microcolumn, typically comprising an electron emitter 110 for emitting electrons indicated by arrows, three electrode layers for emitting, accelerating and controlling electrons and forming the emitted electrons into an effective electron beam A source lens 120, a deflector 150 for deflecting the electron beam, and a focus lens (Einzel lens) 140 for focusing the electron beam onto the sample s. Generally, the deflector is located between the source lens and the Einzel lens. For normal operation of the microcolumn, a negative voltage (about -100 V to -2 kV) is applied to the electron emission source, and the electrode layers of the source lens are generally grounded. As an example of a focusing lens, an Einzel lens focuses an electron beam by grounding the outer electrode layers on both sides and applying a negative voltage (deceleration mode) or a positive voltage (acceleration mode) to the center electrode layer (Used to focus). At the same operating distance, the magnitude of the focusing voltage in the deceleration mode is smaller than in the acceleration mode. The synchronized deflecting voltage is applied to adjust the path of the electron beam to scan the electron beam at a predetermined period on the surface of the sample. The electron lens such as the source lens and the focusing lens includes two or more electrode layers having apertures having a circle or a predetermined shape so as to allow the electron beam to pass through the center, .

As a kind of the electron column, there is a single electron column composed of one electron emission source and electron lenses for controlling the electron beam generated in the electron emission source, and a plurality of electron beams emitted from a plurality of electron emission sources And a multi-type electron column composed of electron lenses. The multi-type electron column includes an electron lens having an electron emission source having a plurality of electron emission source tips in one layer, such as a semiconductor wafer, and an electron lens in which a plurality of apertures are formed in one layer, A combination type electron column in which an electron beam emitted from each electron emission source is controlled to a single lens layer having a plurality of apertures, such as a single electron column, an array in which single electron columns are mounted in a single housing ) Method and the like. In the case of the combination type, the electron emission sources are separately classified, and the lenses can be used in the same manner as the wafer type.

In such an electron column, an electron beam is generated in the electron emission source to scan the sample. Depending on the sample, the electron beam may not be emitted. For example, in an inspection apparatus such as a semiconductor or an LCD, if an electron beam is emitted to an area other than the inspection area, a high-energy electron beam may be charged to damage the sample. Therefore, it is necessary to scan the electron beam in the electron column as necessary, or to prevent the electron beam from coming out of the electron column or reaching the sample. In order to blank the electron beam, a beam blanker is usually used. However, such a beam blanker, when included in an electron column as an additional constituent, includes an additional configuration than a conventional electron column, and a control electrode is added to make the control of the electron column more complicated.

In the case of an ion beam column from a particle beam to a particle beam other than electrons, cations are injected instead of electrons, and the problem of beam blanking occurs in the same way as electron columns.

In order to solve the above problems, it is an object of the present invention to provide a method of performing beam blanking using an electrode of a positive potential electron lens in a conventional particle beam column.

In order to achieve the above object, a blanking method according to the present invention is a method for blanking a beam in a particle beam column,

And blanking the beam by applying a blanking voltage having the same polarity and the same absolute value as the voltage applied to the particle beam source to one or more of the electrode layers of the column or the additional electrode for blanking.

The blanking method according to the present invention is characterized in that the particle beam column comprises an electron lens of a microcolumn, and the blanking voltage is applied to the uppermost layer of the focus lens or the last electrode layer of the source lens of the electron lens .

In addition, the method according to the present invention is characterized in that the particle beam column comprises a microcolumn electron lens, and when the column is used as a single lens, the limiting aperture, which is the last lens layer of the source lens, And the blanking voltage is applied to an electrode serving as a cathode.

The method according to the invention is also characterized in that the column acts as a multi-column.

The beam blanking method according to the present invention can be easily blanked by utilizing the conventional particle beam column as it is, thereby simplifying the structure of the electron column.

Further, when the beam blanking method according to the present invention is used, the beam can be easily blanked, thereby facilitating control of the particle beam column.

The beam blanking method according to the present invention is advantageous in that it can be easily used by applying low energy to a conventional electrode layer (lens layer) in a particle beam column using low energy.

Also, the beam blanking method according to the present invention can utilize the existing structure as it is in the case of a very small particle beam column having a very small size, and it is economical and easy to use because it requires no additional structure.

The advantages of the present invention as described above can best be exhibited in a low energy microparticle beam column.

1 is a cross-sectional view showing a structure of a conventional micro-electron column.
2 is a cross-sectional view showing an example in which beam blanking is performed according to the present invention.
3 is a cross-sectional view showing another example in which beam blanking is performed according to the present invention.
4 is a cross-sectional view showing another example in which beam blanking is performed according to the present invention.
5 is a plan view showing an example of a multi-type electrode layer to which a beam blanking voltage can be applied according to the present invention.

The present invention applies a voltage of the same polarity, which is larger in absolute value than the input voltage of the particle beam source (particle emitting source), to one of the electrode layers constituting the conventional lens.

In the present invention, a particle to be blanked is to blank the particle beam in a particle beam column which generates and controls a beam of particles such as a cation with an electron or an ion. Particularly in the present invention, blanking of the low energy particle beam is advantageous. The larger the energy of the particles, the larger the blanking voltage, but the application of high energy to the intermediate lens layer is not desirable for the control. Thus, it is highly desirable to utilize the blanking method of the present invention in an ultra-small column of low energy and small size. Here, the low energy means particles (electrons or cations) having a beam energy of 2 kV or less, preferably an absolute value, and can be preferably used in a column using a particle beam of 5 kV or less. Particularly in an ultra-small particle beam column including a very small electron column having a very small size by using an electro-static lens as well as a low energy by applying a voltage within several hundred V to the source of the particle emission source, The blanking method can be applied. Of course, the blanking method of the present invention can be utilized in a general particle beam column in addition to the ultra-small particle beam column.

The microparticle beam column refers to a column that can be reduced in size to about 10 mm from the end of the particle emission source to the last electrode of the lens by using an electron lens of a microcolumn, Refers to a particle beam column manufactured using an electrostatic lens of an electron column. Therefore, a new blanking structure is not used in a small and precise microparticle beam column having a small overall size, and a voltage for blanking a beam is sufficient as a low voltage, thereby maximizing utilization value.

Hereinafter, the blanking method of the present invention will be described focusing on a microelectronic column. The reason for this is that in the case of an ion beam, which is another particle beam column, the polarity is opposite, and the method of blanking is the same or similar.

In the beam blanking method of the present invention, if the voltage applied to the electron emission source is -300 V, a voltage of 300 V or more with the same negative voltage is applied to the electrode layer (lens layer) so that electrons emitted from the electron emission source pass through the aperture of the electron lens So that the electrons generated in the electron column can not go into the sample.

The electron beam can be blanked even if a voltage is applied to any one electrode layer (lens layer) of the electron lens, but it is preferable to use an electrode layer configured to be able to apply a predetermined voltage. It is also desirable to blank the electron beam with a voltage as small as possible.

Blanking the electron beam in the electron column according to the present invention allows the electron beam to easily pass through the aperture of the electron lens and proceeding toward the sample. FIG. 2 is a cross-sectional view illustrating an example in which beam blanking is performed according to the present invention, in which a blanking voltage is applied to a limiting aperture 121, which is the lowest lens layer of the source lens 120. As shown, when a blanking voltage is applied to the limiting amplifier 121, which is the last lens layer of the source lens 120, the electrons emitted from the electron emission source 110 are reflected as indicated by arrows and then rise up again. Therefore, it can not pass through the limiting aperture holder 121 and can not reach the sample S. However, if a blanking voltage is not applied to the limiting aperture 121, electrons normally reach the sample as shown in FIG.

FIG. 3 is a cross-sectional view showing another example in which beam blanking is performed according to the present invention, in which a blanking voltage is applied to the uppermost lens layer 141 of the focus lens 140. FIG. As shown in the figure, when a blanking voltage is applied to the upper lens layer 141 of the focus lens 140, electrons emitted from the electron emission source 110 are reflected as indicated by arrows, and then rise up again. Therefore, it can not pass through the upper lens layer 141 and can not reach the sample S. However, if a blanking voltage is not applied to the upper lens layer 141, electrons normally reach the sample again as shown in FIG.

FIG. 4 is a cross-sectional view showing another example in which beam blanking is performed according to the present invention, in which a blanking voltage is applied to the lowest lens layer of the single lens 170. FIG. As shown in the figure, the column includes an electron emission source 110, a single electron lens 170 including three lens layers (electrodes), and a deflector 150 for scanning electrons. It is not a general form of structure, but works with an electron column. The single lens 170 functions as both a source lens and a focus lens. Therefore, the last lens layer of the single electron lens 170 can jointly perform the role of the limiting aperture 121 of the other general electron column and the final lower lens 143 of the focus lens 140, 17, the blanking voltage may be applied to the last lens layer. In this case as well, the electrons emitted from the electron emitting source 110 are reflected as indicated by the arrows and rise up again. Therefore, it can not pass through the lens layer and can not reach the sample S. However, if the blanking voltage is not applied to the lens layer, electrons normally reach the sample as shown in FIG. In the single lens 170, unlike the source lens 120 of FIG. 2, a blanking voltage may be applied to the intermediate lens layer in addition to the last lens layer. That is, when the last lens layer is used by being grounded, the electrode layer can be used if any voltage is applied to any other electrode layer of the lens.

In a typical structure of a micro-electron column, electrons emitted from an electron emission source form a beam, and an electron beam is focused by a focus lens and a deflector and scanned on a sample. Here, as in the examples of FIGS. 2 and 3, It is preferable to apply the blanking voltage to the uppermost electrode layer of the lens or the lowermost electrode layer of the source lens.

That is, it includes a phosphor layer 121 which induces electron emission, an extrator 122 which is an intermediate electron accelerator electrode (lens layer), and a limiting aperture which is a lens layer 123 which forms an effective electron beam A focus lens 140 used mainly by applying a focusing voltage to the intermediate layer 142 based on the limiting aperture lens layer 123 which is the lowermost layer of the source lens 120 and the lens layers 141 and 143 on both outer sides, A negative voltage higher than the voltage of the electron emission source is applied to the upper lens layer 141 of the lower electrode layer 141, so that electrons to which the negative voltage is applied can not pass electrons below the corresponding electrode layer. That is, the negative voltage of the electrode layer pushes the progress of electrons with a force larger than the energy of the electrons, so that the progress of the electron beam is blanked.

In the present invention, blanking of the electron beam does not only mean completely blocking the passage of electrons through the aperture of the electron lens, but may also allow the electron beam to be shot so as not to damage the sample, if necessary.

Although the embodiments described above mainly focus on a micro-electron column for generating electron beams, it is also possible to apply the same or larger voltage to the same polarity as the ion beam in other ion beams having the same lens layer structure to the electrode layer, Can be selected using the same principle as the above electron column.

Also, in the multi-type particle beam column, the beam blanking voltage may be applied to the lens layer in the same position in the same manner as described above. In the case of the multi-beam type, if the beam energy is different for each unit particle beam, the beam blanking voltage can be selected by selecting the voltage magnitude individually, but the largest voltage may be selected and uniformly applied. In particular, in a multi-type column in which a plurality of upper actuators 21 and 91 are formed and used in a large wafer electrode layer 20 and 90 as shown in FIGS. 5A and 5B, And the specific electrode layers are all grounded and used. When the same voltage is applied, the lens layer of FIG. 5A is used. When voltage is to be applied to each unit lens aperture individually As shown in FIG. 5B, a lens layer which is isolated by each aperture and to which an individual voltage can be applied is used.

In the case of the lens layer of FIG. 5A, it is only necessary to apply the determined blanking voltage to all the electrodes equally. 5B, when a voltage is to be applied to each unit lens layer separately, a voltage may be additionally applied so as to be a blanking voltage to an individually applied electrode voltage. In this case, If the blanking is released after applying the entire blanking voltage as shown in FIG. In other multi-type columns, a blanking voltage may be applied to each of the electrode layers similar to that applied to the lens layer of FIG. If necessary, a multi-type lens may be used by individually applying a blanking voltage to another lens layer.

Claims (5)

A method of blanking the beam in a particle beam column,
Wherein the particle beam column comprises an electron lens of a microcolumn,
Blanking the beam by applying a blanking voltage having the same polarity and the same absolute value as the voltage applied to the particle beam source to one or more of the electrode layers of the column,
Applying the blanking voltage to the last electrode layer of the source lens or the uppermost layer of the focus lens in the electron lens,
/ RTI > delete The apparatus of claim 1, wherein the particle beam column comprises a microcolumn electron lens, and wherein the blanking voltage is applied to an electrode serving as a limiting aperture when the column is used as a single lens. Way. The method of claim 1 or 3, wherein the particle beam column is an electron column or an ion beam column. 5. The method of claim 4, wherein the column operates as a multi-column.

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