Extreme ultraviolet light source apparatus utilizing electron beams

Abstract

The extreme ultraviolet (EUV) light source device provided by this invention includes: a discharge cavity maintained under vacuum; an electron beam emitting unit located inside the discharge cavity and used to generate an electron beam; and a metal radiator located inside the discharge cavity and ionized by the electron beam. EUV radiation is achieved in the plasma generated by the metal radiator. The electron beam emitting unit includes: a cathode electrode; multiple emitters located on the cathode electrode and comprising a carbon-based material; and a gate electrode spaced apart from the multiple emitters and located on the multiple emitters, to which a pulsed voltage is applied.

Description

TECHNICAL FIELD

[0001] The present invention relates to an extreme ultraviolet light source apparatus using an electron beam, and more particularly, to a structure of an extreme ultraviolet light source apparatus that is advantageous for large-area. BACKGROUND

[0002] Extreme ultraviolet (EUV) is an electron wave between the X-ray and deep ultraviolet (DUV) regions, i.e., approximately 10 nm to 100 nm wavelength band. Recently, a great deal of effort has been concentrated on developing a miniaturized extreme ultraviolet light source for application fields using the extreme ultraviolet region, such as lithography or nanoscale imaging.

[0003] For example, an extreme ultraviolet lithography device is being used in a nanometer-sized fine pattern process for semiconductor manufacturing. At present, the extreme ultraviolet lithography device is based on a high-energy laser and is entirely dependent on imports. Such an extreme ultraviolet lithography device is very expensive, has a complex internal structure, and is large in size. SUMMARY

[0004] TECHNICAL PROBLEM

[0005] The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide an extreme ultraviolet light source apparatus that has a simple internal structure, a miniaturized size, and reduced manufacturing costs.

[0006] TECHNICAL SOLUTION

[0007] An extreme ultraviolet light source apparatus according to an embodiment of the present invention includes a discharge chamber that maintains a vacuum inside, an electron beam emitting unit that is located inside the discharge chamber and generates an electron beam, and a metal radiator that is located inside the discharge chamber and is ionized by the electron beam. Extreme ultraviolet radiation is achieved in plasma generated in the metal radiator. The electron beam emitting unit includes a cathode electrode, a plurality of emission tips that are located on the cathode electrode and include a carbon-based substance, and a gate electrode that is located on the plurality of emission tips at a distance from the plurality of emission tips and to which a pulse voltage is applied.

[0008] The plurality of emission tips can be formed of emission tips having a pointed end and can include carbon nanotubes. A portion of the gate electrode that faces the plurality of emission tips can be formed of a metal mesh or a perforated plate, and an insulating layer having a thickness greater than a height of each of the plurality of emission tips is provided around the plurality of emission tips between the cathode electrode and the gate electrode.

[0009] The electron beam emitting unit can further include an anode electrode that is located on the gate electrode at a distance from the gate electrode and has an opening through which the electron beam passes, and the anode electrode can be applied with a voltage of 10 kV or more.

[0010] The electron beam emitting unit may further include at least one focusing electrode. The focusing electrode may be located between the gate electrode and the anode electrode.

[0011] The focusing electrode may include: a first focusing electrode; and a second focusing electrode, which is closer to the anode electrode than the first focusing electrode. The first and second focusing electrodes may each have an opening. The opening of the second focusing electrode may be smaller than the opening of the first focusing electrode, and the opening of the anode electrode may be smaller than the opening of the second focusing electrode.

[0012] An electron beam module can be composed of a cathode electrode and multiple emitters and gate electrodes. The electron beam emitting unit can further include a rotating disk, with multiple electron beam modules spaced apart from each other and arranged in a circular pattern on the rotating disk.

[0013] One of the multiple electron beam modules can be aligned with the opening of the anode electrode facing each other, and another electron beam module can be aligned with the opening of the anode electrode facing each other when the rotating disk rotates.

[0014] The metallic radiator can be composed of either molten tin droplets dripping into the plasma region based on an injection device or solid tin composed of a rotating body.

[0015] Invention Effects

[0016] The extreme ultraviolet (EUV) light source device according to the embodiment simplifies its internal structure, achieves miniaturization, and reduces manufacturing costs by configuring an electron beam emitting unit based on a carbon-based emitter instead of a laser device. The EUV light source device according to the embodiment can be used as a photolithography device in the micro-patterning process of semiconductor manufacturing. Attached Figure Description

[0017] Figure 1 This is a structural diagram of an extreme ultraviolet light source device according to the first embodiment of the present invention.

[0018] Figure 2 yes Figure 1 An enlarged view of the electron beam emitting unit in the extreme ultraviolet light source device shown.

[0019] Figure 3 This is a structural diagram of an extreme ultraviolet light source device according to a second embodiment of the present invention.

[0020] Figure 4 yes Figure 3 A three-dimensional view of the electron beam emitting unit in the extreme ultraviolet light source device shown.

[0021] Figure 5 This is a structural diagram of an extreme ultraviolet light source device according to a third embodiment of the present invention.

[0022] Figure 6 and Figure 7 are a perspective view and a sectional view of an electron beam emission unit in an extreme ultraviolet light source apparatus according to a fourth embodiment of the present application, respectively.

[0023] Explanation of symbols

[0024] 100, 101, 102: extreme ultraviolet light source apparatus, 10: discharge chamber, 11: output opening, 12, 13: mirror, 20: electron beam emission unit, 21: cathode electrode, 22: emission pole, 23: gate electrode, 24: anode electrode, 26: first focusing electrode, 27: second focusing electrode, 30: metal radiator, 40: injection device, 50: electron beam module, 51: rotating disk, 52: rotating shaft, 53: drive unit. DETAILED DESCRIPTION

[0025] Hereinafter, embodiments of the present application will be described in detail with reference to the accompanying drawings such that those skilled in the art to which the present application pertains can implement the present application. The present application can be implemented in various different forms, and is not limited to the embodiments described herein.

[0026] Figure 1 is a structural view of an extreme ultraviolet light source apparatus according to a first embodiment of the present application, Figure 2 is Figure 1 is a close-up view of an electron beam emission unit in the extreme ultraviolet light source apparatus shown in FIG. 1.

[0027] Referring to Figure 1 , the extreme ultraviolet light source apparatus 100 of the first embodiment includes a discharge chamber 10, and an electron beam emission unit 20 and a metal radiator 30 positioned inside the discharge chamber 10. The electron beam emission unit 20 is based on a carbon-based emission pole that emits electrons based on an electric field, rather than a laser.

[0028] The discharge chamber 10 is maintained in a vacuum state, and plasma is generated by ionization of the metal radiator 30 and is maintained. For convenience, a plasma maintaining region of a space inside the discharge chamber 10 is referred to as a plasma region.

[0029] The metal radiator 30 is heated by an electron beam and is ionized, and extreme ultraviolet radiation is achieved in the plasma region surrounding the metal radiator 30. That is, the plasma generated by the metal radiator 30 serves as a light source to generate extreme ultraviolet rays. The metal radiator 30 can include one of lithium (Li), indium (In), tin (Sn), antimony (Sb), tellurium (Te), and aluminum (Al), or a mixture of the metals.

[0030] The metal radiator 30 can be a tin droplet, and the discharge chamber 10 can be provided with an injection device 40 to drop the tin droplet. The injection device 40 can be configured to drop a preset volume of the tin droplet at a preset time interval.

[0031] The electron beam emitting unit 20 can be located inside the discharge chamber 10 and irradiate the metal radiator 30 with an electron beam at a side of the metal radiator 30. The electron beam emitting unit 20 includes a cathode electrode 21, a plurality of emitter electrodes 22 located on the cathode electrode 21, a gate electrode 23 located on the plurality of emitter electrodes 22 at a distance from the plurality of emitter electrodes 22, and an anode electrode 24 located on the gate electrode 23 at a distance from the gate electrode 23.

[0032] The plurality of emitter electrodes 22 can be configured with emitter tips having a pointed end, or with a flat emitter layer. Figure 1 and Figure 2 An example of the first case is shown. The plurality of emitter electrodes 22 can include a carbon-based substance such as a carbon nanotube.

[0033] A portion of the gate electrode 23 facing the plurality of emitter electrodes 22 can be configured in a mesh or a perforated plate form. The mesh is a net-like structure woven with thin metal wires spaced apart from each other, and the perforated plate is a structure in which a plurality of openings are formed in a metal plate. The gate electrode 23 allows the electron beam to pass through the spaces between the metal wires or the plurality of openings.

[0034] An unillustrated insulating layer (or insulating spacer layer) can be provided around the plurality of emitter electrodes 22 and between the cathode electrode 21 and the gate electrode 23. At this time, the insulating layer can be formed to have a thickness greater than the height of each of the plurality of emitter electrodes 22 so as to prevent the gate electrode 23 from coming into contact with the plurality of emitter electrodes 22. The gate electrode 23 can be maintained in an insulating state from the cathode electrode 21 and the plurality of emitter electrodes 22 by the insulating layer.

[0035] The anode electrode 24 can be configured with a metal plate having an opening 241 formed therein to allow the electron beam to pass therethrough. The center of the opening 241 can be aligned with the center of the plurality of emitter electrodes 22 and the center of the gate electrode 23. The pitch between the emitter electrodes 22 and the gate electrode 23 can be smaller than the pitch between the gate electrode 23 and the anode electrode 24.

[0036] The cathode electrode 21 can be grounded, the gate electrode 23 can be applied with a pulse voltage, and the anode electrode 24 can be applied with a high voltage of 10 kV or more. Thereby, an electric field can be formed around the plurality of emitter electrodes 22 by the voltage difference between the cathode electrode 21 and the gate electrode 23, the plurality of emitter electrodes 22 emit an electron beam by the electric field, and the emitted electron beam is accelerated by the high voltage of the anode electrode 24.

[0037] At this time, the pulse voltage of the gate electrode 23 is a voltage having a high frequency or a low pulse width, and can have a high frequency characteristic of, for example, greater than or equal to 100 kHz. Such a pulse voltage can cause the electron beam to be switched at high speed, thereby producing an effect of reducing the driving power.

[0038] The electron beam accelerated toward the anode electrode 24 irradiates the metal radiator 30 through the opening 241 of the anode electrode 24 and heats the metal radiator 30. Extreme ultraviolet rays are generated in a plasma generated from the heated ionized metal radiator 30, and the extreme ultraviolet rays are output to the outside of the discharge chamber 10 through the output opening 11 of the discharge chamber 10.

[0039] At this time, a mirror 12 can be provided between the anode electrode 24 and the metal radiator 30, which focuses the extreme ultraviolet rays to the output opening 11. The mirror 12 has an opening through which the electron beam passes, and includes a reflection surface that is recessed toward the metal radiator 30. The mirror 12 can be a multilayer in which molybdenum (Mo) and silicon (Si) are alternately stacked.

[0040] The extreme ultraviolet light source apparatus 100 of the first embodiment can simplify the internal structure, have a size that is miniaturized, and reduce the manufacturing cost by configuring the electron beam emission unit 20 instead of a laser device. The extreme ultraviolet light source apparatus 100 of the first embodiment can be used as a photolithography apparatus in a fine pattern process of semiconductor manufacturing.

[0041] Figure 3 is a configuration view of an extreme ultraviolet light source apparatus according to a second embodiment of the present application, Figure 4 is Figure 3 is a perspective view of an electron beam emission unit in the extreme ultraviolet light source apparatus shown in FIG. 1.

[0042] Referring to Figure 3 and Figure 4 , a part of the electron beam emission unit 20 in the extreme ultraviolet light source apparatus 101 of the second embodiment is configured by a rotary type. For example, the electron beam module 50 is configured by the cathode electrode 21 and the plurality of emission electrodes 22 and the gate electrode 23, and a plurality of the electron beam modules 50 are arranged at a distance from each other and in a circular arrangement on a rotary disk 51.

[0043] The electron beam emission unit 20 can include the rotary disk 51, a rotary shaft 52 fixed to the rotary disk 51, and a driving unit 53 combined with the rotary shaft 52 and configured to rotate the rotary shaft 52. The rotary disk 51 can be a circular disk, and the driving unit 53 can be configured by a step motor, but is not limited to these examples. A part of the rotary shaft 52 and the driving unit 53 can be located outside the discharge chamber 10.

[0044] The rotation axis 52 is offset in the vertical direction from the opening 241 of the anode electrode 24, and one of the plurality of electron beam modules 50 is aligned with the opening 241 of the anode electrode 24 so as to face each other. If the electron beam module 50 aligned with the anode electrode 24 so as to face each other reaches the lifetime after a certain period of use, the drive unit 53 rotates the rotary disk 51 to align another electron beam module 50 with the anode electrode 24 so as to face each other.

[0045] As described above, the plurality of electron beam modules 50 are arranged on the rotary disk 51, and the electron beam modules 50 can be used in turn by rotating the rotary disk 51. In this case, not only the replacement period of the electron beam emission unit 20 is increased, but also the lifetime of the discharge chamber 10 is extended.

[0046] The structure of the extreme ultraviolet light source apparatus 101 of the second embodiment is the same as or similar to that of the first embodiment described above, except that the electron beam emission unit 20 is configured in a rotary manner.

[0047] Figure 5 is a configuration view of an extreme ultraviolet light source apparatus according to a third embodiment of the present application.

[0048] Referring to Figure 5 In the extreme ultraviolet light source apparatus 102 of the third embodiment, the discharge chamber 10 can be cylindrical. The metal radiator 30 can include solid tin and be configured in a rotary manner. The metal radiator 30 configured in a rotary manner is effective in extending the replacement period because of the long lifetime, and the structure is very simple compared to an injection apparatus for dropping tin droplets.

[0049] The electron beam emission unit 20 can ionize the metal radiator 30 by irradiating the metal radiator 30 with an electron beam, and achieve extreme ultraviolet radiation in a plasma region around the metal radiator 30. The output opening 11 can be located on one side of the metal radiator 30, and the mirror 13 can be located on the opposite side, with the metal radiator 30 as the center. The mirror 13 reflects the extreme ultraviolet light toward the output opening 11, thereby increasing the intensity of the extreme ultraviolet light passing through the output opening 11.

[0050] The structure of the extreme ultraviolet light source apparatus 102 of the third embodiment is the same as or similar to that of the first embodiment described above, except for the shape of the discharge chamber 10 and the structure of the metal radiator 30.

[0051] Figure 6 and Figure 7 are a perspective view and a sectional view of an electron beam emission unit according to a fourth embodiment of the present application, respectively.

[0052] Referring to Figure 6 and Figure 7The electron beam emitting unit 20 of the fourth embodiment further includes at least one focusing electrode between the gate electrode 23 and the anode electrode 24. The focusing electrode can include a first focusing electrode 26 on the gate electrode 23 and a second focusing electrode 27 on the first focusing electrode 26.

[0053] The gate electrode 23 can include a metal mesh 231 corresponding to the plurality of emitters 22 and a support 232 fixed to the edge of the metal mesh 231 and used to support the metal mesh 231. In addition, a first insulating layer 251 can be provided around the plurality of emitters 22 and between the cathode electrode 21 and the support 232.

[0054] A second insulating layer 252 is between the gate electrode 23 and the first focusing electrode 26, which can insulate the gate electrode 23 and the first focusing electrode 26, and a third insulating layer 253 is between the first focusing electrode 26 and the second focusing electrode 27, which can insulate the first focusing electrode 26 and the second focusing electrode 27. In addition, a fourth insulating layer 254 is between the second focusing electrode 27 and the anode electrode 24, which can insulate the second focusing electrode 27 and the anode electrode 24.

[0055] The second insulating layer 252, the first focusing electrode 26, the third insulating layer 253, the second focusing electrode 27 and the fourth insulating layer 254 each have an opening for the electron beam to pass through. The second insulating layer 252 and the third insulating layer 253 and the fourth insulating layer 254 have openings of the same size.

[0056] The opening 261 of the first focusing electrode 26 can have a diameter smaller than the size of the metal mesh 231 of the gate electrode 23, and the opening 271 of the second focusing electrode 27 can have a diameter smaller than the diameter of the opening 261 of the first focusing electrode 26. The opening 241 of the anode electrode 24 can have a diameter smaller than the diameter of the opening 271 of the second focusing electrode 27. That is, the first focusing electrode 26, the second focusing electrode 27 and the anode electrode 24 have openings with sizes decreasing in turn.

[0057] The first focusing electrode 26 and the second focusing electrode 27 can be applied with a negative (-) voltage. Thus, the electron beam passing through the metal mesh 231 of the gate electrode 23 is focused by the repulsive force applied by the first focusing electrode 26 and the second focusing electrode 27 while passing through the opening 261 of the first focusing electrode 26 and the opening 271 of the second focusing electrode 27 in turn.

[0058] The electron beam emitting unit 20 with the first focusing electrode 26 and the second focusing electrode 27 can reduce the size of the electron beam reaching the metal radiator 30 by focusing the electron beam, which results in reducing the generation of metal debris and prolonging the service life of the metal radiator 30.

[0059] The structure of the extreme ultraviolet light source apparatus of the fourth embodiment is the same as or similar to that of any one of the above-described first and third embodiments except for the structure of the electron beam emitting unit 20.

[0060] The above describes the preferred embodiments of the present application, but the present application is not limited thereto, and various modifications can be made within the scope of the claims and the detailed description of the application and the drawings, which of course also belong to the protection scope of the present application.

[0061] Industrial applicability

[0062] The extreme ultraviolet light source apparatus according to the embodiment of the present application can simplify the internal structure, have a size of miniaturization, and reduce the manufacturing cost by configuring an electron beam emitting unit based on a carbon-based emitter instead of a laser device. The extreme ultraviolet light source apparatus according to the embodiment of the present application can be used as a photolithography device in a fine pattern process of semiconductor manufacturing.

Claims

1. An extreme ultraviolet light source apparatus, characterized by comprising: including: a discharge chamber, an inside of which is kept in vacuum; an electron beam emitting unit, which is located inside the discharge chamber and is used to generate an electron beam; and a metal radiator, which is located inside the discharge chamber and is ionized by the electron beam, extreme ultraviolet radiation is realized in plasma generated by the metal radiator, the electron beam emitting unit includes: a cathode electrode; a plurality of emitters, which are located on the cathode electrode and include carbon-based substances; and a gate electrode, which is located on the plurality of emitters at a distance from the plurality of emitters and is applied with a pulsed voltage, the electron beam emitting unit further includes an anode electrode, which is located on the gate electrode at a distance from the gate electrode and has an opening for the electron beam to pass through, the anode electrode is applied with a voltage greater than or equal to 10 kV, an electron beam module is composed of the cathode electrode, the plurality of emitters and the gate electrode, the electron beam emitting unit further includes a rotating disc, a plurality of electron beam modules are arranged on the rotating disc at a distance from each other in a circular shape.

2. The extreme ultraviolet light source device according to claim 1, wherein the plurality of emitters are composed of emitter tips with pointed ends and include carbon nanotubes.

3. The extreme ultraviolet light source device according to claim 2, wherein a portion of the gate electrode, which faces the plurality of emitters, is composed of a metal mesh or a perforated plate, an insulating layer is provided between the plurality of emitters and between the cathode electrode and the gate electrode, and the thickness of the insulating layer is greater than the height of each of the plurality of emitters.

4. The extreme ultraviolet light source device according to claim 1, wherein the electron beam emitting unit further includes at least one focusing electrode, which is located between the gate electrode and the anode electrode and is applied with a negative voltage.

5. The extreme ultraviolet light source device according to claim 4, wherein the focusing electrode includes: a first focusing electrode; and a second focusing electrode, which is closer to the anode electrode than the first focusing electrode.

6. The extreme ultraviolet light source device according to claim 5, wherein the first focusing electrode and the second focusing electrode each have an opening, the opening of the second focusing electrode is smaller than the opening of the first focusing electrode, and the opening of the anode electrode is smaller than the opening of the second focusing electrode.

7. The extreme ultraviolet light source device according to claim 1, wherein one of the plurality of electron beam modules is aligned with the opening of the anode electrode to face each other, and another of the plurality of electron beam modules is aligned with the opening of the anode electrode to face each other when the rotating disc rotates.

8. The extreme ultraviolet light source device according to any one of claims 1 to 7, wherein the metal radiator is composed of one of a tin liquid drop based on a dropping device that drops into a plasma region and a solid tin composed of a rotating body.

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