JP3335798B2 - Electrostatic lens and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic lens used for an electron microscope and an electron / ion beam application apparatus, and a method of manufacturing the same.

[0002]

2. Description of the Related Art An electrostatic lens has conventionally been used as an electron gun lens for an electron microscope or the like and a focusing lens for an ion beam apparatus.

FIG. 4 schematically shows a typical conventional cylindrical electrostatic lens for an electron beam and its ray diagram.

In FIG. 6, reference numeral 100 denotes a position of an electron gun, and an electron beam 101 is emitted from the position 100 of the electron gun at a certain opening angle and forms an image on a sample 102. The first electrode 103 is grounded to the earth 104, and the center second electrode 105 is a negative potential power source 1 for forming a lens electric field.
06, and the third electrode 107 is grounded to the earth 104.

[0005] The electrostatic lens 108 having the structure shown in FIG.
Is generally called an Einzel lens, and includes three electrodes 103, 105, and 107. As described above, the electrostatic lens 108 is formed by combining a plurality of electrodes 103, 105, and 107 having a cylindrical shape or a disk shape. When a voltage is applied from the power supply 106 to the second electrode 105, an electron beam forms an image on the sample stage 102. FIG. 7 shows the potential distribution of the electrostatic lens 108. As shown in FIG. 7, a potential peak (−VP) occurs at the second electrode 105,
The potential approaches zero potential toward the first and third electrodes 103 and 107. In addition, generally, there is often an offset corresponding to an acceleration voltage instead of a zero potential.

FIG. 8 shows a specific configuration example of the electrostatic lens 110. The electrostatic lens 110 shown in FIG. 8 has an asymmetric electrode, that is, has an asymmetrical potential distribution on the axis to reduce aberration, and is called an asymmetrical Eizel lens. As in FIG. 6, the first electrode 111
Is maintained at a ground potential, the central second electrode 112 is maintained at a negative potential forming a lens electric field, and the third electrode 113 is maintained at a ground potential. The voltage applied to the second electrode 112 differs depending on the type of the beam. In FIG. 8, each of the electrodes 111, 112,
113 is held by a ceramic holder 114 for insulation.

The electrostatic lens 108 shown in FIGS.
At 110, the electron beam 101 emitted from the position 100 of the electron gun forms an image on the sample stage 102 through the electrostatic lenses 108 and 110.

[0008] Further, as shown in FIG.
The zero electrodes 111, 112, and 113 are held and fixed by a ceramic holder 114 that is an insulator. The electrodes 111, 112, 113 are held by the ceramic holder 114 with an accuracy of about 10 μm in both coaxiality and concentricity.

Further, the ceramic holder 11 is located on the center axis.
4 so that each electrode 111, 112, 113 can not be seen directly.
Is determined, and thereby, charging can be prevented. The electrostatic lens 10 shown in FIG.
Also in 8, each of the electrodes 103, 105, and 107 is held and fixed by a ceramic holder (not shown). FIG. 10 shows the beam diameter blur rate (beam diameter blur amount / beam diameter × 100%) that determines the coaxiality of the electrostatic lens and the lens performance.
Shows the relationship with The beam diameter corresponds to the resolution, and it can be seen from FIG. 10 that when the coaxial accuracy deteriorates, the beam diameter blur increases and the resolution decreases.

[0010]

Conventionally, in the conventional electrostatic lenses 108 and 110 shown in FIGS. 6 and 8, even if the individual components constituting the electrostatic lens are manufactured with high precision, the following will be described. As described above, the accuracy of the coaxiality had to be reduced by combining the components.

In the electrostatic lens 110 shown in FIG.
A plurality of, for example, three electrodes 111, 112, 113 are held and fixed by a ceramic holder 114 or the like.

However, a plurality of electrodes 111, 11
When the electrodes 2 and 113 are held and fixed by the ceramic holder 114, each electrode 11
The work of accurately arranging 1, 112 and 113 is complicated,
Not easy to assemble.

In the case of the electrostatic lens 110 shown in FIG. 8, each of the electrodes 111, 112 and 113 is formed in a complicated shape for the purpose of preventing electrification in the ceramic holder 114 and reducing lens aberration. That is, in order to prevent electrification, it is necessary to make the wall surface of the ceramic holder 114 invisible from above the electron beam trajectory. For this reason, the electrodes 111, 112, and 113 need to be shaped so as to overlap each other. is there. In addition, it is necessary to prevent charging and reduce lens aberrations, and the shape of each electrode is further complicated. When the shape of each of the electrodes 111, 112, and 113 is complicated, the shape of the ceramic holder 114 is also complicated, and the overall shape of the electrostatic lens 110 is increased. For this reason, there was a problem that manufacturing was not easy and the cost was high.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide an electrostatic lens which can be easily processed and assembled and has improved lens accuracy, and a method of manufacturing the same.

[0015]

In order to achieve the above object, a method of manufacturing an electrostatic lens according to the present invention is directed to a method of manufacturing an electrostatic lens for diverging or converging a charged particle beam. The high-resistance material column and the low-resistance material column are alternately inserted without any gaps into the insertion through holes,
Propagation penetration through which the charged particle beam propagates to the low-resistance material column and the high-resistance material column in a state where the low-resistance material column and the high-resistance material column are integrated with the insulating cylinder. It is characterized by forming a hole.

Preferably, at least one or more of the high-resistance material column and the low-resistance material column are inserted.

Preferably, the low-resistance material column is made of a metal material, and the high-resistance material column is made of a SiC material.

Preferably, the low resistance material column is made of a SiC material having a low resistivity component ratio, and the high resistance material column is made of a SiC material having a high resistivity component ratio.

Preferably, a low-resistance columnar portion having a component ratio giving a low resistivity and a high-resistance columnar portion having a component ratio giving a high resistivity have a predetermined length in the longitudinal direction in the insertion through hole. The columnar body of the SiC material formed alternately and repeatedly is inserted, and the propagation through-hole for forming the propagation through-hole through which the charged particle beam propagates is formed in the longitudinal direction of the columnar body of the SiC material.

The electrostatic lens according to the present invention is an electrostatic lens for diverging or converging a charged particle beam, wherein a high-resistance material column and a low-resistance material column are inserted into an insertion through hole of an insulating cylinder. Are inserted alternately with no gap therebetween, and the low-resistance material column and the high-resistance material column are integrated with the low-resistance material column and the high-resistance material column integrated with the insulating cylinder. A transmission through hole through which the charged particle beam propagates.

[0021]

The high-resistance material column and the low-resistance material column are alternately inserted into the insertion through-hole of the insulating cylinder without any gap therebetween, and the low-resistance material column and the high-resistance material column are insulated from each other. By forming a propagation through-hole in the low-resistance material column and the high-resistance material column in a state of being integrated with the cylindrical body, the respective lenses constituting the electrostatic lens in which the through-hole is formed in advance are coaxially aligned. Since there is no need to assemble, it is possible to provide an electrostatic lens having high coaxiality without lowering coaxiality in the assembling process.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of the electrostatic lens of the present invention. In FIG. 1, an electrostatic lens 1 has a low resistance material column made of a metal material and a high resistance material column 4, 6 containing SiC or the like inserted into an insertion through hole 3 formed in an insulating cylindrical body 2 such as ceramics. 5 are inserted and fixedly held.
At the center of the high resistance material pillars 4 and 6 and the low resistance material pillar 5, a cylindrical propagation through hole 7 for electron beam propagation is provided.
Are formed. The propagation through-hole 7 is formed in a state where the high-resistance material pillars 4 and 6 and the low-resistance material pillar 5 are inserted into the insertion through-hole 3 and the insulating cylindrical body 2 is fixed and held. Insertion and fixing of the high-resistance material pillars 4 and 6 and the low-resistance material pillars 5 to the insulating cylindrical body 2 are performed by hard fitting such as shrink-fitting or bonding, and the shaft is misaligned when the propagation through hole 7 is processed. Should not occur. Through holes 8 extending from the outer surface of the insulating tubular body 2 to the side surfaces of the high resistance material columnar bodies 4 and 6 and the low resistance material columnar body 5;
9 and 10 are formed. An electric wire 12 for grounding the high-resistance material pillars 4 and 6 to the ground 11 is provided in the through holes 8 and 9, and a power supply for applying a negative voltage to the low-resistance material pillar 5 in the through hole 10. An electric wire 13 connected to 14 is provided.

The electron beam emitted from the emission position 15 of the electron beam passes through the propagation through hole 7 and forms an image on the sample 16 on the sample stage.

The insertion through-hole 3 does not necessarily have to have a cylindrical shape, and therefore does not need to be a cylindrical column of the high resistance material columns 4 and 6 and the low resistance material column 5.
May be a polygonal column shape or an asymmetric column shape. Therefore, the high-resistance material column members 4 and 6 and the low-resistance material column member 5 are, for example, as shown in FIG. Should be fine. In addition, even if the low resistance material is an alloy,
It may be a pure metal such as 1 or Ti, or a ceramic material containing TiB ₂ .

Next, the operation and effect of the electrostatic lens 1 of this embodiment will be described. For comparison, FIG. 9 shows a conventional electrostatic lens 120. As shown in FIG. 9, a propagation through-hole 122 is formed in the high-resistance material columnar body 121, and an electric conductive film 123 is coated in an intermediate portion of the propagation through-hole 122. A voltage is applied by the power supply 124. However,
In the conventional electrostatic lens 120, the electric conductive film 123
Is coated on the deep inside of the propagation through-hole 122, so that the coating itself is not easy, and it is not easy to form the electric conductive film 123 at a predetermined position with high accuracy. .

On the other hand, in the electrostatic lens 1 according to the present embodiment, the low resistance material column 5 is inserted into the insertion through hole 3 to form the propagation through hole 7. Does not require a coating, and the electrostatic lens 1 has a configuration that can be easily manufactured.

Next, a method of manufacturing the electrostatic lens 1 shown in FIG. 1 will be described with reference to FIG. In FIG.
An insertion through-hole 3 penetrating in the longitudinal direction and a through-hole 8 penetrating from the inner surface to the outer surface in the insulating cylindrical body 2 made of ceramics;
9 and 10 are formed in advance. Next, the high resistance material columnar body 6, the low resistance material columnar body 5, and the high resistance material columnar body 4 formed in the insertion through hole 3 corresponding to the hole shape are inserted in this order.
And fixedly held on the insulating cylinder 2 by hard fitting such as shrink fitting or bonding.

The high-resistance material column 6, the low-resistance material column 5 and the high-resistance material column 4 are pressed in the longitudinal direction so as to contact each other without any gap. Flatness so that they can contact each other without gaps,
For example, it is processed with a flatness of 3 μm.

Next, while the high-resistance material pillars 4 and 6 and the low-resistance material pillar 5 are fixed and held on the insulating cylinder 2, a cylindrical propagation through-hole 7 is formed at the center of these. .

Next, the operation of the thus manufactured electrostatic lens will be described. By applying a negative voltage to the low-resistance material column 5 made of a metal cylinder by the external power supply 14, a peak of a negative potential is formed around the low-resistance material column 5 in the propagation through hole 7 as shown in FIG. Is generated, and a potential distribution approaching zero potential is formed toward the high resistance material pillars 4 and 6 on both sides. As a result, the electrostatic lens 1 composed of three lenses equivalent to that shown in FIG. 6 is formed, and the control of the electron beam passing through the propagation through hole 7 becomes possible.

According to the structure of this embodiment, the propagation through hole 7
Is formed in a state in which the high-resistance material columnar bodies 4 and 6 and the low-resistance material columnar body 5 are fixedly held on the insulating cylinder 2, so that the lenses constituting the electron lens 1 have high coaxiality and It is equivalent to the alignment.

The high coaxiality can be easily achieved only by forming the propagation through-hole 7 in a state where the high resistance material pillars 4 and 6 and the low resistance material pillar 5 are fixedly held to the insulating cylinder 2. It can be realized and does not require complicated positioning. Therefore, complicated processing is reduced, the accuracy of the shape is improved, the processing cost and the processing time are reduced by half, and the coaxiality and concentricity on the central axis are about 1 μm or less because the propagation through hole 7 is formed after assembly. It can be completed with the assembly accuracy.

A conventional electrostatic lens 110 shown in FIG.
Each of the electrodes 111, 112, 113
It is not necessary to screw it on to assemble with high precision.

A conventional electrostatic lens 110 shown in FIG.
In order to prevent electrification, the electrodes 111, 112,
It is necessary to make the shape of the electrodes 113 so that they overlap each other so that the wall of the ceramic holder 114 is not directly visible from the electron beam, and it is necessary to reduce the lens aberration at the same time. I was As a result, the shape of the ceramic holder 114 has been complicated, and the overall shape of the electrostatic lens 110 has been increased.

On the other hand, in the present embodiment, the propagation through holes 7
Is formed through each of the high-resistance material pillars 4 and 6 and the low-resistance material pillar 5 and the wall surface of the insulating cylindrical body 2 cannot be seen from the electron beam passing through the propagation through hole 7. The electron beam does not induce charging on the wall surface of the insulating cylinder 2 and charging is prevented. Also, despite the simple shape of the high-resistance material pillars 4 and 6 and the low-resistance material pillar 5 as pillars,
Since the charge can be prevented, the lens aberration can be reduced by appropriately selecting the length in the longitudinal direction of each of the high-resistance material pillars 4 and 6 and the low-resistance material pillar 5. As a result, the shape of the insulating cylindrical body 2 does not need to be complicated, and the entire shape of the electrostatic lens 1 can be reduced in size. For example, while the outer diameter of the electrostatic lens 110 shown in FIG. 8 is about 20 mm, in this embodiment, the outer diameter can be reduced to 10 mm or less.

In this embodiment, an example is shown in which the electrostatic lens is constituted by three pillars of the high resistance material pillars 4 and 6 and the low resistance material pillar 5, but the number is not limited to three. Instead, four or more high resistance material pillars and low resistance material pillars may be used as long as they are alternately arranged. Thus, a plurality of lenses such as a gun lens unit such as an electron gun and an objective lens unit can be integrated.

Although the low-resistance material column 5 is made of a metal material, it is made of a SiC material having a low-resistivity component ratio, and the high-resistance material pillars 4 and 6 are made of a SiC material having a high-resistivity component ratio. It may be made of a material. As the SiC material having a low resistivity component ratio, a SiC material containing about 50% of SiC in a ceramic material and having a resistance of about 10 ⁻⁶ Ωcm can be used. As the SiC material having a high resistivity component ratio, a SiC material containing about 10% of SiC in a ceramic material and having a resistance of about 10 ³ to 10 ⁵ Ωcm can be used.

In the above-described embodiment, the case where the high-resistance material pillars and the low-resistance material pillars formed separately from each other are alternately inserted into the insertion through-holes 3 has been described. However, the present invention is not limited to this, and a high resistance material column and a low resistance material column may be integrally formed as follows. That is, a SiC material formed by alternately repeating a low-resistance columnar portion having a component ratio giving a low resistivity and a high-resistance columnar portion having a component ratio giving a high resistivity at a predetermined length in the longitudinal direction. A columnar body may be manufactured, and the columnar body may be inserted into the insertion through hole 3 and fixed and held, and the propagation through hole 7 may be formed in the longitudinal direction of the SiC material columnar body.

Next, as another embodiment of the present invention, a multi-pole electrode used for a beam scanner, an astigmatism corrector, a polarizer or the like will be described with reference to FIGS.
FIG. 4 shows a beam scanner 20, which has a high resistance material column 21 containing SiC or the like. The high resistance material column 21 has eight branch holes 22 penetrating in the longitudinal direction and branching in eight directions in the radial direction. Eight electrode terminal holes 23 extending in eight directions in the radial direction are formed between the branch holes 22 at a longitudinally intermediate portion of the high resistance material columnar body 21.

As shown in FIG. 5, each electrode terminal hole 23
, An arbitrary voltage can be applied at an arbitrary timing by a corresponding power supply 24. By combining the timing of applying a voltage to each of the electrode terminal holes 23, for example, by applying a voltage for beam scanning, FIG.
As shown by the arrow, the electron beam can be scanned on the sample stage 25.

According to this embodiment, since the plurality of branch holes 22 and the plurality of electrode terminal holes 23 are formed in the high resistance material column 21, the plurality of branch holes and the plurality of electrode terminal holes are separately manufactured. It is not necessary to perform complicated alignment with each other unlike incorporation into a cylindrical body, and a plurality of branch holes 2 are positioned at a predetermined position of the high-resistance material columnar body 21 by using an NC processing machine or the like.
2 and the electrode terminal hole 23 can be integrally formed.

The beam scanner 20 of the present embodiment can be combined with a plurality of lenses to form a beam inspection apparatus as an integrated system. Since the beam inspection apparatus can be formed as an integrated system, each lens and beam scanner 2 can be integrated.
The alignment accuracy between the zero electrodes can also be improved.

In the above description, an electron beam has been described as an example of a charged particle beam. However, the present invention can be applied to another charged particle beam such as an ion beam instead of an electron beam.

[0044]

As described above, according to the structure of the present invention, the propagation through-hole is formed in a state where the high resistance material pillars and the low resistance material pillars are alternately inserted and fixedly held. The electrostatic lens can be easily manufactured without the need for complicated positioning. As a result, complicated machining is reduced, shape accuracy is improved, machining cost and machining time can be shortened, and a transmission through hole is drilled after assembly. Assembly accuracy can be realized.

After the high resistance material column and the low resistance material column are integrated, the propagation through hole is formed, so that the coaxiality between the lens made of the high resistance material column and the lens made of the low resistance material column is formed. , The concentricity can be made highly accurate, for example, about 1 μm or less, and as a result, an electrostatic lens with low aberration can be obtained.

Further, since it is not necessary to mechanically assemble a plurality of metal electrodes using a ceramic holder as in a conventional electrostatic lens, the lens diameter and the overall shape can be reduced and the structure can be simplified.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of an electrostatic lens according to the present invention.

FIG. 2 is a process chart showing the order of assembling the electrostatic lens according to the present invention.

FIG. 3 is a perspective view showing an example in which the electrostatic lens according to the present invention is configured using a rectangular cylinder.

FIG. 4 is a perspective view showing a beam scanner according to the present invention.

FIG. 5 is a sectional view taken along line AA in FIG. 4;

FIG. 6 is a schematic sectional view showing a conventional electrostatic lens.

FIG. 7 is a view showing a potential distribution on a central axis of the electrostatic lens shown in FIG. 6;

FIG. 8 is a schematic sectional view showing a conventional electrostatic lens.

FIG. 9 is a schematic sectional view showing another conventional electrostatic lens.

FIG. 10 is a diagram showing the relationship between the coaxiality of the electrostatic lens and the beam diameter blur rate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electrostatic lens 2 Insulating cylinder 3 Insertion through hole 4, 6 High resistance material column 5 Low resistance material column 7 Propagation through hole 8, 9 10 Through hole 12 Power supply 15 Electron beam 16 Sample stand 20 Beam scanner

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-64-81151 (JP, A) JP-A-6-187901 (JP, A) JP-A-2-152140 (JP, A) JP-A-6-187140 124650 (JP, A) JP-A-59-31546 (JP, A) JP-A-8-31336 (JP, A) JP-A-8-321273 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01J 37/12 H01J 9/14 H01J 9/18 H01J 23/08-23/087 H01J 37/04

Claims (4)

(57) [Claims] 1. A method of manufacturing an electrostatic lens for diverging or converging a charged particle beam, wherein a high-resistance material column and a low-resistance material column are alternately inserted into an insertion through hole of an insulating cylinder without gaps therebetween. The charged particle beam propagates to the low-resistance material column and the high-resistance material column in a state where the low-resistance material column and the high-resistance material column are integrated with the insulating cylinder. A method for manufacturing an electrostatic lens, characterized by forming a propagation through-hole which is formed. 2. The method according to claim 1, wherein the low resistance material column is made of a metal material, and the high resistance material column is made of a SiC material. 3. The low resistance material columnar body is made of a SiC material having a low resistivity component ratio, and the high resistance material columnar body is made of a SiC material having a high resistivity component ratio. Item 2. The method for manufacturing an electrostatic lens according to Item 1. 4. An electrostatic lens for diverging or converging a charged particle beam, wherein a high-resistance material column and a low-resistance material column are alternately inserted into an insertion through hole of an insulating cylinder without gaps therebetween. Then, the charged particle beam propagates to the low-resistance material column and the high-resistance material column in a state where the low-resistance material column and the high-resistance material column are integrated with the insulating cylinder. An electrostatic lens having a propagation through hole formed therein.