WO2008032971A1

WO2008032971A1 - Lens assembly for electron column

Info

Publication number: WO2008032971A1
Application number: PCT/KR2007/004379
Authority: WO
Inventors: Ho Seob Kim
Original assignee: Cebt Co. Ltd.
Priority date: 2006-09-11
Filing date: 2007-09-10
Publication date: 2008-03-20
Also published as: KR20090052350A; TW200836230A

Abstract

The present invention relates to a lens assembly for an electron column and, more particularly, to a lens assembly that can prevent voltage or current, which is applied to any one of the lens layers of the electron column, from leaking to another layer.

Description

LENS ASSEMBLY FOR ELECTRON COLUMN

Technical Field

[1] The present invention relates to a lens assembly for an electron column and, more particularly, to a lens assembly that can prevent voltage or current, which is applied to any one of the lens layers of the electron column, from leaking to another layer. Background Art

[2] In a conventional electron column including a microcolumn, a lens is provided with two or more electrode layers, and is manufactured by bonding these electrode layers with Pyrex layers or other insulating layers.

[3] FIG. 1 shows a sectional view of a conventional lens for an electron column. A source lens or a focus lens is formed in such as way that three electrode layers 10, 30 and 50 are insulated by insulating layers 20 and 40, such as Pyrex layers, which are interposed therebetween, and are layered using anodic bonding or epoxy bonding, etc. The lens electrode layers 10, 30 and 50 are provided with respective through-holes 15, 35 and 55, so that an electron beam can pass through the through-holes 15, 35 and 55. The insulating layers 20 and 40 are provided with respective holes 25 and 45. Generally, the insulating layers 20 and 40 are formed to have a size smaller than that of the lens electrode layers 10, 30 and 50, or to have the same size as that of the lens electrode layers 10, 30 and 50, and the holes are formed to be larger than the through- holes 15, 35 and 55 so as not to affect the path of electrons or an electron beam, which passes through the holes of the respective lens electrode layers. Accordingly, the outer surfaces 29 and 49 of the insulating layers 20 and 40, as shown in the drawing, form respective linear surfaces between the lens electrode layers. That is, linear connection is made from one lens electrode to another lens electrode.

[4] The lens assembly of FIG. 1 is typically made of a conductor or a highly-doped silicon material, has the function of an electrode plate, is supplied with voltage or current, and is used as an electron lens, such as a source lens or a focus lens. Furthermore, deflectors, each of which deflects an electron beam, may be implemented using the lens manufacturing method. An electrode layer of FIG. 1 may be modified as a deflector acquired by dividing the electrode layer into several electrodes based on the central hole. The bonding and layering of the electrode layers with the insulating layers interposed between the electrode layers is the same as for the deflector.

[5] However, in the conventional lens-layer structure, shown in FIG. 1, when voltage is applied to any one of the electrode layers, the case where another electrode layer is affected through the surfaces of the corresponding insulating layer occurs. Generally, in portions in which the conducting parts of the electrode layers and the insulating layers come into contact with each other, current does not flow well through the section of the insulating layers, but minute current flows along the remaining non- contact portions of the insulating layers. In this phenomenon, when a voltage is applied to a single electrode layer, charges accumulate on the surfaces of a corresponding insulating layer, as in a surface charging effect, in which charges accumulate on the surfaces of an insulating layer, and thus another electrode layer is affected. That is, voltage or current applied to a specific electrode layer leaks through the surfaces of a corresponding insulating layer. This phenomenon occurs along the shortest distance from the outer contact surface between one electrode layer and one insulating layer to another electrode layer. Accordingly, in the case where the lens electrode layers and the Pyrex layers are layered without being flush with each other, the above-described phenomenon occurs along the side lines and surfaces of each insulating layer. Furthermore, the above-described phenomenon also occurs in the holes of the insulating layers of FIGS. 1.

[6] Accordingly, in the case where a voltage or current is applied to a specific electrode layer in order to precisely control a lens or a deflector, another electrode layer may be affected by leakage through the surfaces of a corresponding insulating layer, or different electrode layers may be mutually affected. Accordingly, a problem occurs in that the lens or the deflector cannot be precisely controlled. Disclosure of Invention

Technical Problem

[7] Accordingly, in order to solve the above problems, the present invention provides an electron lens assembly, in which the structure of insulating layers and/or electrode layers is changed so that the leakage of current or voltage through the surfaces of the insulating layers interposed between the electrode layers can be prevented, or can be decreased. Technical Solution

[8] In order to solve the above problems, the present invention provides an electron lens assembly, in which electrode layers and insulating layers are adhered or bonded, wherein a surface path or a line path reaching from a contact surface or a contact line between one insulating layer and one electrode layer to another electrode layer or a support is not linear.

[9] In an electron lens assembly in which electrode layers are divided and insulated by insulating layers, which are interposed therebetween, the present invention functions to prevent the phenomenon in which voltage or current, which is applied to a specific electrode layer, leaks through the surfaces of the insulating layer, and thus affects another electrode layer.

[10] In the electron lens assembly, the voltage or current leakage phenomenon, occurring at the surfaces of an insulating layer interposed between electrodes, occurs chiefly along the shortest distance between the surfaces, other than the contact surfaces of the electrode layers, rather than occurring through the middle of the section of the insulating layer. In the conventional electron lens assembly, shown in FIG. 1, the insulating layer 20, interposed between the electrode layers 10 and 30, performs an insulation function between the lower electrode layer 30 and the upper electrode layer 10. However, planar or linear connection is made at the outer contact surfaces between the insulating layer 20 and the electrode layers 10 and 30, and at the surface of the hole, and thus the leakage of current or voltage through the surface of the insulating layer can easily occur. Accordingly, in the lens assembly of the present invention, the contact surface distance of an insulating layer between electrode layers is increased, and thus the phenomenon in which current leaks through the surfaces of the insulating layer is decreased. For this purpose, curves or irregularities are formed in the insulating layer and/or the electrode layers. Generally, an insulating layer having a small size is interposed between the electrode layers. In this case, if the size of the insulating layer is increased, irregularities are naturally formed between the electrode layers, and thus the surface passage distance between the electrode layers is increased. However, since the hole of the insulating layer must be larger than the holes of the lens electrode layers, the surface leakage phenomenon occurs along the internal surfaces of the holes of the insulating layers.

[11] Accordingly, in the present invention, long-hole type depressions or irregularity type depressions are formed over all of the contact surfaces of the electrode layers or the insulating layer and in a hole region, so that the distance from an outer contact surface or line between one electrode layer and one insulating layer to an outer contact surface or line between a neighboring electrode layer and the insulating layer can be maximized, or the side surfaces of the insulating layer and the internal surface of a central hole are rounded, or depressions are formed in the side surfaces of the insulating layer and the internal surface of the central hole. As a result, the shortest surface distance along the insulating layer that is into contact with the electrode layers is increased. That is, the insulating layer and/or the electrode layers are processed or deformed, so that the shortest distance from a contact line between a first electrode layer and an insulating layer (generally, the shape of a rectangular or circular insulating layer) to a contact line between a second electrode layer and the insulating layer is increased.

[12] Furthermore, in the case where a deflector is manufactured using a micromachining process, such as a semiconductor manufacturing process, as in a lens, the above- described lens assembly structure may be applied to the deflector. In the case where the deflector is formed using two or more electrode layers, the technology of the present invention may be applied to the deflector in the same manner as in a typical electron lens assembly. In the case where the deflector is used as one electrode layer, the deflector is bonded to another lens assembly with an insulating layer interposed therebetween, or is fastened to another support in the state in which it is bonded to an insulating layer. In the case where the deflector is bonded to another lens and is used, an insulating layer is interposed between the deflector and the lens, and thus the deflector may be used in the same manner as in the above-described lens assembly. [13] Furthermore, in the case where one electrode layer is bonded to one surface of an insulating layer, and the other surface of the insulating layer is fastened to another conductor, or to a support having characteristics similar to that of a conductor, through bonding, the technology of the present invention may be used to prevent the leakage of voltage or current through the surfaces of the insulating layer from occurring between the electrode layer and the support.

Advantageous Effects

[14] The electron lens assembly of the present invention decreases or eliminates the current or voltage leakage phenomenon that occurs along the surfaces of the insulating layer, thus enabling the precise control of the lens.

Brief Description of the Drawings [15] FIG. 1 is a sectional perspective view showing a conventional lens assembly, which is cut in half; [16] FIG. 2 is a sectional view showing a lens assembly according to an embodiment of the present invention;

[17] FIG. 3 is a perspective view of the insulating layer of FIG.2;

[18] FIG. 4 is a sectional view showing a lens assembly according to another embodiment of the present invention; [19] FIG. 5 is a sectional view showing a lens assembly according to another embodiment of the present invention; [20] FIG. 6 is a sectional view showing a lens assembly according to another embodiment of the present invention; [21] FIG. 7 is a sectional view showing a lens assembly according to another embodiment of the present invention; [22] FIG. 8 is a sectional view showing a modification of the insulating layer according to the present invention; and [23] FIG. 9 is a sectional view showing a multiple lens electrode layer based on the insulating layer of FIG. 8. Mode for the Invention

[24] Various embodiments of the present invention are described with reference to the accompanying drawings below. Here, it should be noted that the various embodiments are used to provide descriptions so that those skilled in the art can easily understand the present invention, but do not limit the scope of the present invention.

[25] FIG. 2 is a sectional view showing an embodiment of a lens assembly having a structure in which a single insulating layer 220 is interposed between two electrode layers 210 and 230, in which the structure of the insulating layer 220 is altered. FIG. 3 is a perspective view of the insulating layer of FIG. 2.

[26] In the present embodiment, in order to eliminate the phenomenon in which voltage or current leaks through the surfaces of the insulating layer 220 interposed between two electrode layers, the upper and lower surfaces of the ends of the insulating layer 220 are partially removed to thus form surface depressions 221. Surface hole depressions 222 are formed in the central hole of the insulating layer. Accordingly, as shown in the sectional view of FIG. 2, the distance along the insulating layer from an outer contact surface 219 between the upper electrode layer and the insulating layer to an outer contact surface 239 between the lower electrode layer and the insulating layer is longer than the distance along the insulating layer of FIG. 1, that is, the distances of respective straight lines indicated by the arrows A and B. Accordingly, the leakage of the current through the surfaces of the insulating layer between the upper and lower electrode layers is decreased. In the embodiment of FIG. 2, the distance is increased because a crooked line is formed, as indicated by the arrow C.

[27] Although the depressions 221 and 222 may be formed in the upper and lower surfaces of the insulating layer, as shown in FIG. 3, it is possible that one surface of the insulating layer may be formed to be flat if the insulating layer is attached to a surface other than a lens layer (for example, if the insulating layer is attached to a housing). However it is desiralbe that the depressions 221 and 222 be formed in the upper and lower surfaces of the insulating layer in order to minimize the current or voltage leakage.

[28] Unlike the embodiments of FIGS. 2 and 3, FIG. 4 is configured such that depressions or grooves 411, 412, 431 and 432 are formed in lens electrode layers 410 and 430, and thus the same effect as in FIG. 2 can be achieved.

[29] The electrode layers 410 and 430 of FIG. 4 have a structure in which the ends of surfaces of electrode layers 410 and 430, which come into contact with an insulating layer 420, are partially removed, as in the insulating layer 220 of FIGS. 2 and 3. The electrode layers 410 and 430 of FIGS. 4 are provided with respective outer surface depressions 411 and 431 and respective central hole depressions 412 and 432, as in the insulating layer 220 of FIG. 2. Accordingly, in the present embodiment, the insulating layer 420 may be used without separately processing it or altering the shape thereof. In this case, an insulating layer 420 having an area wider than that of a portion remaining after the surfaces of the electrode layer are partially removed must be used. If an insulating layer 420 having a smaller area or the same area is used, it is pointless to remove the surfaces of the ends of the electrode layers 410 and 430. Furthermore, in a central hole 425 as well, an insulating layer 420 having a hole smaller than the processed portions of the electrode layers must be used.

[30] FIG. 5 is a sectional view showing a lens assembly according to another embodiment of the present invention. In the present embodiment, the ends and hole of an insulating layer 520 are formed to have a doughnut shape, and the insulating layer 520 has a rounded end 523. The distance from the outer contact surfaces 519 of an upper electrode layer 510 to the outer contact surfaces 519 of a lower electrode layer is increased due to the rounded end 523 of the insulating layer 520 and the hole 525.

[31] FIG. 6 is a sectional view showing a lens assembly according to another embodiment of the present invention. An insulating layer 620, interposed between electrode layers 610 and 630, is formed to have depressions 624 by causing the rounded end of the doughnut-shaped insulating layer of FIG. 5 to be reversely concave.

[32] FIG. 7 shows a typical lens, in which two insulating layers 720 and 740 are used between three electrode layers 710, 730 and 750.

[33] FIG. 8 shows a sectional view of an insulating layer 820, in each of outer surfaces of which a plurality of concave depressions 824 is formed. In FIG. 8, respective escaping hole depressions 822 are merely formed in the upper and lower portions of a hole 825, as in FIG. 6, but the plurality of concave depressions are formed in each of the outer surfaces of the insulating layer 820. The forming of the depressions 824 according to the present embodiment may be applied to the embodiments of FIGS. 2, 5 and 6 in the same manner. The depressions 824 may be formed in various shapes, such as a round shape and a V-type shape.

[34] In FIG. 9, in order to implement a multiple lens electrode layer, the insulating layer

820 of FIG. 8 is provided with a plurality of holes 925. A number of escaping depressions 922 corresponding to the number of holes 925 is formed in the upper and lower portions of the holes 925. Depressions 924 are formed in each of the outer surfaces of the entire layer. The multiple lens electrode layer, which is configured such that a plurality of holes is provided in a single electrode layer, is used as individual electron lens electrodes based on respective holes. The individual lens electrodes are insulated based on the respective holes, and thus operation can be individually performed on the holes.

[35] Although the insulating layer 920 of the multiple electrode layer is illustrated using the embodiment FIG. 8, all of the above-described embodiments may be used to implement the multiple electrode layer. That is, escaping depressions may be formed not only in the insulating layer, but also in the electrode layer, as in the embodiment of FIG. 4. In this case, escaping depressions are formed based on respective holes, as in FIG. 4, and escaping depressions are also formed in the outer surfaces of the entire electrode layer.

[36] As described in the above embodiments, in the present invention, it is important that the distance along the insulating layer from the outer contact surface of the upper electrode layer to the outer contact surface of the lower electrode layer should be increased, and various methods may be used to increase the distance. Therefore a depression can have a shape like "

C

" or a plurity of depression can be formend in the ourter surface of an insulating layer or an electrode layer. In the case where the insulating layer is formed to have a size greater than the electrode layer, and the central hole is formed using any one of the methods used in the above-described embodiments, the construction can be simply implemented. However, this embodiment is not preferred because it is an attempt to further reduce the size of an electron column, but is preferred because it can be easily used in the case where the margin is sufficient in a single electron column.

[37] Although, in the drawings, the size of the escaping depressions is arbitrarily illustrated, the leakage of current or voltage through the surfaces of an insulating layer depends on the shortest distance between electrode layers, and thus the size of the escaping depressions is determined according to the characteristics of an electron lens assembly (including a deflector assembly) that is used. That is, in order to precisely control the electron lens, it is necessary to increase the size of the escaping depressions and to increase the distance between the electrode layers, as in FIG. 8. In contrast, in the case where it is not necessary to precisely control the electron lens, it is necessary merely to form escaping depressions only in the surfaces. Industrial Applicability

[38] The lens assembly of the present invention could be used for an electron column in a SEM, a semiconductor lithography, or an inspection equipment for a semiconductor or LCD.

Claims

[1] An electron lens assembly, in which electrode layers and insulating layers are adhered or bonded, wherein: a surface or a line reaching from a contact surface or a contact line between one insulating layer and one electrode layer to another electrode layer or a support is not linear.

[2] The electron lens assembly according to claim 1, wherein escaping depressions are formed in respective surfaces of the electrode layers, which come into contact with the insulating layers, so that a side surface of the contact surfaces between the electrode layers and the insulating layer is not linear.

[3] The electron lens assembly according to claim 1, wherein escaping depressions are formed in respective surfaces of the insulating layers that are in contact with the electrode layers, so that a side surface of the contact surfaces between the electrode layers and the insulating layer is not linear.

[4] The electron lens assembly according to claim 3, wherein the escaping depressions are irregularities, long holes, rounded depressions, or V-shaped depressions.

[5] The electron lens assembly according to claim 4, wherein the escaping depressions are formed in outer surfaces of the insulating layers, or are formed in the outer surfaces of the insulating layers and in inner surfaces of central depressions, and are formed to have identical shapes, or are formed in two or more shapes.

[6] The electron lens assembly according to any one of claims 1 to 5, wherein the electrode layers or the insulating layers are a multiple lens electrode layer.