Patent Application
20080259309
1. Field of the Invention
The present invention relates to a stage apparatus which holds a reticle (original) in, for example, an exposure apparatus, an exposure apparatus, and a device manufacturing method.
2. Description of the Related Art
An exposure apparatus for manufacturing a semiconductor device has a reticle stage and wafer stage for aligning a reticle (mask) as an original and a wafer as a substrate. To attain high-precision alignment in such an alignment stage apparatus, a method of providing a coarse moving stage which moves with a large stroke and a fine moving stage which moves with a small stroke to the apparatus is disclosed in each of Japanese Patent Laid-Open No. 2000-106344 and “Ultraprecision Manufacturing Technology, Vol. 3; Technology of Measurement and Control” (first edition, Jul. 15, 1995, issued by Fuji Technosystem, pp. 20-27, supervised by Akira Kobayashi).
The support frame 306 also has a pair of electromagnets 308 which sandwich the stage 301 in the Y-axis direction. Each electromagnet 308 functions as an electromagnetic coupling by generating an attraction force together with a magnetic plate 307 provided to the stage 301. As the support frame 306 accelerates/decelerates with a high acceleration/deceleration, it transmits an acceleration/deceleration force to the stage 301 using the attraction force of one of the pair of electromagnets 308.
In recent years, a demand has arisen for a stage apparatus with a higher precision. For example, as shown in
It is an object of the present invention to suppress an object held by a stage from deforming due to deformation of the stage generated upon accelerating/decelerating it.
According to the first aspect of the present invention, a stage apparatus which includes a stage and moves the stage in at least a first direction comprises a holding unit fixed on the stage to extend in the first direction, the holding unit including a first portion and a second portion inserted between the first portion and the stage, the first portion including a holding surface configured to hold an object, wherein a length of the second portion in the first direction is less than a length of the first portion in the first direction.
According to the second aspect of the present invention, a stage apparatus which includes a stage and moves the stage in at least a first direction comprises a holding unit extending along the first direction and having a first surface for holding an object and a second surface which is connected to the stage, the holding unit having a hinge portion whose ends are determined by two slits extending from both ends of the holding unit in the first direction towards a central portion of the holding unit, wherein a length of the hinge portion in the first direction is less than a length of the first surface in the first direction and a length of the second surface in the first direction.
According to the present invention, it is possible to suppress an object held by a stage from deforming due to deformation of the stage generated upon accelerating/decelerating it.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
The coarse moving stage 203 has, at its central portion, an opening 210 which propagates exposure light. The fine moving stage 202 which mounts a reticle 201 is inserted in the opening 210 and supported with low rigidity from the coarse moving stage 203 via a spring mechanism (including, for example, an air bearing; not shown). A fine movement linear motor 205 and electromagnetic couplings 207 are interposed between the fine moving stage 202 and the coarse moving stage 203. The fine movement linear motor 205 can finely move the fine moving stage 202 relative to the coarse moving stage 203. The fine movement linear motor 205 drives the fine moving stage 202 in a non-contact manner using the Lorentz force between the coil and the magnet, as exemplified in the prior art. The fine movement linear motor 205 can be arranged so as to finely drive the fine moving stage 202 in three axial directions, i.e., in the X direction, Y (scanning) direction, and Z (vertical) direction. The fine movement linear motor 205 can also be arranged so as to finely drive the fine moving stage 202 in six axial directions including three rotation directions about the X-, Y-, and Z-axes, in addition to the above-described directions. The number of axes and axial directions may be freely changed in accordance with design details such as the required precision and space. A laser interferometer 211 measures the position of the fine moving stage 202 in three axial directions or six axial directions.
Each electromagnetic coupling 207 has, for example, an I core 207a as a magnetic material attached on the fine moving stage 202, an E core 207b as a magnetic material attached on the coarse moving stage 203, and an electromagnetic coupling coil 209 wound around the E core 207b.
Reticle holding units 208 each are fixed on the fine moving stage 202 and made of a material identical to or different from that of the fine moving stage 202. This material is an elastically deformable member. The elastically deformable member here includes general elastic metal and resin materials, and general fragile glass and ceramic materials.
Each reticle holding unit 208 has a chucking mechanism for holding and aligning the reticle 201, and a measurement light transmission hole for aligning the reticle 201. More specifically, light from a light emitting unit (not shown) irradiates the reticle 201 from above, is transmitted through a mark formed on the reticle 201, propagates through a measurement light transmission hole, and enters a light-receiving unit provided under the fine moving stage 202. The light-receiving unit comprises, for example, a camera sensor, which allows for detecting the relative position between the reticle 201 and the light-receiving unit. Furthermore, the fine moving stage is moved so that a reference mark formed on it falls within the detection range of the light-receiving unit, thereby detecting the relative position between the reference mark and the light-receiving unit. This makes it possible to obtain information on the relative positional shift between the reticle 201 and the fine moving stage 202 from the movement amount of the stage measured by the interferometer and the relative position between the light-receiving unit and each mark. The resultant relative position shift information can be reflected in the driving of the fine moving stage 202.
The fine moving stage 202 deforms upon receiving an acceleration/deceleration force. However, elastic hinges 213 provided in the same direction as the deformation direction of the fine moving stage 202 suppress deformation of the fine moving stage 202 from being transmitted to the reticle 201. At the same time, the elastic hinges 213 suppress heat generated by the fine moving stage 202 from being transferred to the reticle 201.
An effect of suppressing the reticle holding unit 208 from deforming due to deformation of the fine moving stage 202 as described above can be controlled by changing the size of the elastic hinge portion of the reticle holding unit 208. More specifically, assume that the reticle holding unit 208 deforms by 100 nm due to deformation of the fine moving stage 202 upon accelerating/decelerating it with a certain acceleration. If the allowable deformation amount of the reticle 201 is 10 nm, the elastic hinges 213 in the reticle holding unit 208 reduce its deformation to 1/10. Considering the nature of general elastic deformation, it is possible to reduce the deformation of the reticle 201 to 1/10 by adjusting the ratio between the sizes of the elastic hinge 213 and reticle holding unit 208 to a deformation reduction ratio (in this example, 1/10). For example, if the reticle holding unit 208 has a size of 130 mm, the size of the elastic hinge 213 is 130 mm× 1/10=13 mm. When the conventional reticle holding unit deforms by 100 nm, this deformation is directly transmitted to the reticle. That is, it is possible to suppress the deformation of the reticle 201 by adjusting the length of the second portion in the first direction, in which the fine moving stage 202 moves, to be less than that of the third portion. Although the length of the second portion is 10% of the lengths of the first portion and third portion in the above-described arrangement, the length ratio of the second portion can be changed by taking account of a reticle deformation suppression action and stable reticle holding action. For example, even when the length of the second portion is adjusted to 70% or less of the lengths of the first portion and third portion by attaching importance to stable reticle holding, the reticle deformation can be suppressed sufficiently. However, when importance is attached to reticle deformation suppression, the length ratio of the second portion is desirably 50% or less and, more desirably, 30% or less.
As shown in
When the reticle holding unit 208 is made of a low-thermal expansion material such as Invar, ceramic, or glass, it is possible to prevent the fine moving stage 202 from thermally deforming due to heat generated by an actuator as it drives the reticle stage 2 with high acceleration. To reduce the thermal deformation, the linear expansion coefficient of the low-thermal expansion material is preferably 0.7 ppm/° C. or less around 23° C. and, more preferably, 0.1 ppm/° C. or less for more effective deformation suppression.
The stage apparatus according to this embodiment is applicable not only to a reticle stage but also to a high-precision stage apparatus. Although an arrangement in which a coarse moving stage coarsely moves in the scanning direction as one axial direction has been exemplified above, an arrangement in which it coarsely moves in two axial directions may be adopted. As a concrete example, the stage apparatus according to this embodiment is applicable to a wafer stage similarly built in an exposure apparatus.
The exposure apparatus according to this embodiment projects and transfers by exposure a circuit pattern formed on a reticle onto a wafer, and may adopt a step & repeat projection exposure scheme or step & scan projection exposure scheme. The illumination optical system 1 illuminates a reticle on which a circuit pattern is formed, and has a light source unit and illumination system. The light source unit uses, for example, a laser as a light source. The laser can be, for example, an ArF excimer laser with a wavelength of about 193 nm, a KrF excimer laser with a wavelength of about 248 nm, or an F2 excimer laser with a wavelength of about 153 nm. The type of laser is not particularly limited to an excimer laser, and may be, for example, a YAG laser. The number of lasers used is not particularly limited as well. When a laser is used as the light source, a light beam shaping optical system which shapes a collimated light beam from the laser light source into a desired beam shape, and an incoherent optical system which converts a coherent laser light beam into an incoherent light beam are preferably used. In addition, the light source which can be used for the light source unit is not particularly limited to a laser. It is also possible to use one or a plurality of lamps such as a mercury lamp or xenon lamp.
The illumination optical system 1 illuminates a mask and includes, for example, a lens, mirror, light integrator, and stop. The projection optical system 3 can be, for example, an optical system including a plurality of lens elements alone, an optical system (catadioptric system) including a plurality of lens elements and a concave mirror, an optical system including a plurality of lens elements and a diffractive optical element such as kinoform, or an optical system including a total reflection mirror.
The reticle stage 2 and wafer stage 4 can be moved by, for example, a linear motor. When the exposure apparatus adopts a step & scan projection exposure scheme, the stages 2 and 4 move in synchronism with each other. An actuator is separately provided to at least one of the wafer stage 4 and reticle stage 2 to align the pattern of the reticle 6 onto the wafer. Such an exposure apparatus can be used to manufacture a device, on which a micropattern is formed, for example, a semiconductor device such as a semiconductor integrated circuit, a micromachine, or a thin film magnetic head.
Applying the alignment apparatus according to this embodiment to an exposure apparatus makes it possible to provide an exposure apparatus which attains high precision and high throughput by suppressing deterioration in precision due to the influence of deformation of a fine moving stage.
An embodiment of a device manufacturing method using the above-described exposure apparatus will be explained next with reference to
In step S1 (circuit design), the circuit of a semiconductor device is designed. In step S2 (mask fabrication), a mask is fabricated on the basis of the designed circuit pattern. In step S3 (wafer manufacture), a wafer is manufactured using a material such as silicon. In step S4 (wafer process) called a preprocess, the above-described exposure apparatus forms an actual circuit on the wafer by lithography using the mask and wafer. In step S5 (assembly) called a post-process, a semiconductor chip is formed using the wafer manufactured in step S4. This step includes an assembly step (dicing and bonding) and packaging step (chip encapsulation). In step S6 (inspection), the semiconductor device manufactured in step S5 undergoes inspections such as an operation confirmation test and durability test. After these steps, the semiconductor device is completed and shipped in step S7.
When the exposure apparatus according to this embodiment is used for exposure in such a device manufacturing process, it is possible to produce a device with high precision or high throughput and, consequently, to manufacture a microdevice and/or inexpensive device.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2007-110833, filed Apr. 19, 2007, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2007-110833 | Apr 2007 | JP | national |
