1. Field of the Invention
The present invention relates to an optical technique, and more particularly, to an optical element and an optical apparatus.
2. Description of the Related Art
In recent years, the improvement in the finer microstructure of the semiconductor device has been further advanced, and even use of extreme ultraviolet (EUV) light having a wavelength of 5 to 15 nm in an exposure system for manufacturing a semiconductor device is now considered. However, EUV light is easily absorbed into all the substances. Further, when the EUV light is used, a refractive index of the substance becomes in the vicinity of 1.0, and hence a dioptric system that has been used in the conventional exposure system cannot be used. For this reason, in an exposure system in which EUV light is used, a catoptric system constituted of a plurality of mirrors is employed. However, the reflectance of a mirror for EUV light is normally about 70%, and 30% of energy of EUV light incident on the mirror is absorbed into the mirror, thereby causing thermal expansion. For this reason, a method in which an air bag is arranged inside the mirror, and deformation of the mirror resulting from the thermal expansion is corrected by the expansion/contraction of the air bag is proposed (see, for example, Jpn. Pat. Appln. KOKAI Publication No. 2004-56125). However, it has been difficult to control the expansion/contraction of the air bag in the order of nanometer, and by extension it has been impossible to control the surface roughness of the mirror surface in the order of nanometer.
Thus, realization of an optical element and an optical apparatus capable of controlling the surface roughness with a high degree of accuracy has been desired.
According to a first aspect of the invention, there is provided an optical element, which includes:
a substrate;
a magnetostrictive film arranged on the substrate, a film thickness of the magnetostrictive film varying in accordance with intensity of a magnetic field; and
a reflection film arranged on the magnetostrictive film and reflects light.
According to a second aspect of the invention, there is provided an optical apparatus, which includes:
a stage including a holder provided with a plurality of holes arranged in a carrying surface thereof for carrying an optical element provided with a magnetostrictive film which is arranged on a substrate, a film thickness of the magnetostrictive film varying in accordance with intensity of a magnetic field, and a reflection film arranged on the magnetostrictive film and reflecting light;
a plurality of magnetic field generation parts embedded in the plurality of holes of the holder; and
a control mechanism for controlling the magnetic field generated by each of the plurality of magnetic field generation parts, and controlling the film thickness of the magnetostrictive film of the optical element.
Embodiments of the present invention will be described below with reference to the accompanying drawings. In the description of the following drawings, the same or similar parts are denoted by the same or similar reference symbols. Incidentally, the following embodiments exemplify the devices and methods for embodying the technical idea of the present invention, and the technical idea of the present invention does not specify the arrangements or the like of the constituent components to limit them to the following.
An optical apparatus according to a first embodiment of the present invention is an exposure system for manufacturing a semiconductor device. As shown in
Further, the exposure system includes a projection optical system 131 for propagating light reflected by the mask 40, and a wafer stage 48 for holding a wafer 57 coated with a resist film to be exposed to the light propagated by the projection optical system 131.
The light source emits laser light having wavelengths from the infrared range to the visible range. For example, an yttrium-aluminum-garnet (YAG) laser, excimer laser, or the like by the semiconductor laser excitation is emitted from the light source 31.
A condensing lens 32 is arranged adjacent to the light source 31. The condensing lens 32 condenses the laser light emitted from the light source 31 at a focal point 33. The focal point 33 is supplied with xenon (Xe) gas. The Xe gas is brought to a high temperature by being irradiated with laser light. Further, the Xe is excited to a plasmatic state, and when the Xe makes the transition to a low-potential state, EUV light in the soft X-ray range having a wavelength of 12 to 14 nm is released. The released EUV light is condensed by an elliptical mirror 34, and is reflected by a parabolic mirror 35.
The illumination optical system 130 by which the EUV light reflected by the parabolic mirror 35 is propagated includes reflecting mirrors 36 and 37, a condenser mirror 38, and a light path folding mirror 39. The EUV light is reflected by the reflecting mirrors 36 and 37, further the EUV light reflected and condensed by the condenser mirror 38 is reflected by the light path folding mirror 39, and then reaches a mask 40 fixed to the mask stage 41 by the electrostatic attraction force.
The projection optical system 131 is arranged below the mask 40. Further, the wafer stage 48 for holding a wafer 57 is arranged below the projection optical system 131. The projection optical system 131 includes a condenser mirror 47.
The EUV light reflected by the mask 40 is reflected and condensed by a condenser mirror 42, and is reflected by light path folding mirrors 43 and 44. Further, the EUV light is reflected and condensed by a condenser mirror 45, and is reflected by a light path folding mirror 46. The EUV light reflected by the light path folding mirror 46 is reflected and condensed by a condenser mirror 47, and then converges into a focus on a resist film applied to the surface of the wafer 57. The magnification of the projection optical system 131 is, for example, ¼. The EUV light is absorbed into air, and hence it is desirable that the environment of the illumination optical system 130, the projection optical system 131, and the like be maintained in a vacuum.
As shown in the top view of
A power source 62 (62a, 62b, 62c, 62d, . . . ) and a switch 63 (63a, 63b, 63c, 63d, . . . ) are connected to each of the plurality of magnetic field generation parts 61. For example, when the switch 63a is turned on, a current is supplied from the power source 62a to the magnetic field generation part 61a, and a magnetic field is generated by the magnetic field generation part 61a. The above applies to the magnetic field generation parts 61b, 61c, and so forth.
Each of the plurality of switches 63 and each of the plurality of power sources 62 are connected to a control mechanism 150 shown in
The mask 40 which is an optical element according to the first embodiment includes, as shown in
As a material for the substrate 10, a low thermal expansion material (LTEM) such as molten silica (Si) doped with titanium (Ti) can be used. As a material for the magnetostrictive film 11, iron group elements such as iron (Fe), cobalt (Co), nickel (Ni), and the like, or lanthanoids such as lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), thulium (Tm), ytterbium (Yb), and lutetium (Lu), or a Heusler alloy (an alloy containing, for example, Mn, Al, and Cu) can be used.
The reflection film 12 is a multilayer film formed by alternately accumulating Mo thin films made of molybdenum (Mo) and Si thin films made of silicon (Si) one on top of the other to form a multilayer structure of 40 to 50 layers. For example, the film thickness of an Mo thin film and an Si thin film forming a pair is 6.6 nm. Further, the ratio of the film thickness of the Mo thin film to the film thickness of the paired Mo thin film and the Si thin film is 0.33.
A protective film 13 for preventing oxidation and the like of the reflection film 12 is arranged on the reflection film 12. As a material for the protective film 13, Si, ruthenium (Ru) or the like can be used. An intermediate layer 14 is partly arranged on the protective film 13. The intermediate layer 14 is arranged to protect the reflection film 12 and the protective film 13 from dry etching when the absorption film 15 is formed on the reflection film 12.
As a material for the intermediate layer 14, silane oxide (SiO2) and the like can be used. As a material for the absorption film 15, aluminum (Al), tantalum nitride (TaN), tungsten (W), and the like can be used. The intermediate layer 14 and the absorption film 15 are partly arranged on the reflection film 12 to be correspondent to a circuit pattern of the semiconductor device to be manufactured.
Incidentally, the mask 40 is fixed to the mask stage 41 shown in
As shown in
Conversely, for example, in the case where there is a concave part on the undersurface of the reflection film 12 as shown in
The mechanism which changes the film thickness of the magnetostrictive film 11 will be described below in more detail. When the magnetic field is applied to the magnetostrictive film 11, the magnetization directions 113 of the plurality of magnetic domains 111a to 111d are made uniform so as to be coincident with the direction 115 of the magnetic field as shown in
When light is absorbed into the absorption film 15 and the reflection film 12 of the mask shown in
Further, when the substrate 10 of the mask 40 is not flat because of a defect or the like, or when the support body 141 of the mask stage 41 is curved, or when there are particles such as dust or the like between the mask 40 and the mask stage 41, too, the image on the mask 40 on the wafer 57 shown in
Conversely, the film thickness of the magnetostrictive film 11 of the mask 40 shown in
Further, the film thickness of the magnetostrictive film 11 of the mask 40 shown in
Furthermore, the plurality of magnetic field generation parts 61 are provided in the mask stage, and hence it is not necessary to provide the mask 40 with a complicated mechanism for controlling the film thickness other than the magnetostrictive film 11. It is also unnecessary to provide electric wiring or mechanical connection between the mask 40 and the mask stage 41. Accordingly, it becomes possible to hold down the manufacturing cost of the semiconductor device. Although in the manufacturing job site of the semiconductor device, replacement of the mask is frequently performed, the manufacturing cost of the semiconductor device can be held down by using the mask 40 according to this embodiment.
Next, with reference to
(a) First, a substrate 10 shown in
(b) As shown in
(c) As shown in
(d) As shown in
Next, the method of manufacturing the semiconductor device according to this embodiment will be described below with reference to the flowchart of
(a) In step S101, in accordance with the procedures described previously with reference to
(b) In step S103, the intensity of the magnetic field to be applied to the magnetostrictive film 11 in order to correct the protrusion or the recess of the absorption film 15 and the protective film 13 is determined by using the relationship between the magnetic field and the amount of variation in the film thickness of the magnetostrictive film 11 which is shown in
(c) In step S105, the control mechanism 150 shown in
(d) In step S106, a wafer 57 coated with a resist film by spin coating is arranged on the wafer stage 48 shown in
Incidentally, the thermal expansion of the reflection film 12 of the mask 40 may be predicted by a simulation or the like in step S102 of
According to the method of manufacturing the semiconductor device shown above, even when a protrusion or a recess is present in the absorption film 13, the protective film 13, or the reflection film 12, it becomes possible to correct the protrusion or the recess of the absorption film 15 and the protective film 13 by controlling the film thickness of the magnetostrictive film 11. Accordingly, it becomes possible to make the allowable range of the surface roughness of the absorption film 15 and the protective film 13 wide at the time of manufacturing the mask 40. Therefore, it becomes possible to reduce the manufacturing cost of the mask 40, and improve the manufacturing yield of the mask 40.
Further, the substrate 10 of the mask 40 shown in
In the first embodiment, although the mask 40 shown in
As shown in
The reflecting mirror stage 341 includes, as in the case of the first embodiment, a support body 241 provided with a plurality of openings, a plurality of magnetic field generation parts 161 (161a, 161b, 161c, 161d, . . . ) inserted in the plurality of openings of the support body 241, a plurality of power sources 162 (162a, 162b, 162c, 162d, . . . ) connected to the plurality of magnetic field generation parts 161, and a plurality of switches 163 (163a, 163b, 163c, 163d, . . . ) each of which is arranged between each of the plurality of magnetic field generation parts 161 and each of the plurality of power sources 162 to be connected to the corresponding magnetic field generation part 161 and the corresponding power source 162.
For example, when an aberration or flare is caused in the projection optical system 131 shown in
As described above, according to the second embodiment, it is possible to provide a reflecting mirror capable of controlling the surface roughness with a high degree of accuracy.
In the embodiments described above, although the exposure system and the reflecting mirror have been described as the optical apparatus, besides the present invention can be applied to an optical microscope, a hologram formation apparatus, and the like.
Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.
Number | Date | Country | Kind |
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2006-162072 | Jun 2006 | JP | national |
This is a Continuation Application of PCT Application No. PCT/JP2007/058650, filed Apr. 20, 2007, which was published under PCT Article 21(2) in Japanese. This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2006-162072, filed Jun. 12, 2006, the entire contents of which are incorporated herein by reference.
Number | Date | Country | |
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Parent | PCT/JP2007/058650 | Apr 2007 | US |
Child | 12332628 | US |