JP2002353105A - Illumination optical apparatus, aligner provided with the same and method of manufacturing microdevice - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing an illumination optical apparatus, having higher optical efficiency which can continuously vary the lighting conditions, without using a zoom optical system, an aligner provided with the same illumination optical apparatus and a microdevices utilizing the same aligner. SOLUTION: An optical flux emitted from a light source 1 is incident on a relay optical system 2, made incident on a movable multi-mirror 3, and then made incident to a fly-eye lens 5 via the relay optical system 4 and then uniformly lights a mask 8, after passing condenser optical systems 6, 7. The movable multi-mirror 3 is formed, by including many fine element mirrors 30 arranged as in an array. Each element mirror 30 is movable and individually driven and controlled in the sloping angle and sloping direction. Therefore, the movable multi-mirror 3 divides the light flux into fine units of each reflecting surface and makes the light flux deflect in a predetermined angle in the predetermined direction. Accordingly, the cross-section of the light from the light source can be converted to the desired shape and size.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable for use in manufacturing micro devices such as semiconductor devices, liquid crystal display devices, image pickup devices, CCD devices, and thin film magnetic heads by using photolithography technology. The present invention relates to a novel illumination optical device, an exposure apparatus having the illumination optical device, and a method for manufacturing a micro device.

[0002]

2. Description of the Related Art In recent years, circuit patterns of micro devices such as semiconductor integrated circuits have been miniaturized. Accordingly, selection of illumination conditions in a photolithography process is a very important factor, and it is required to perform exposure while changing illumination conditions for each circuit pattern to be exposed and each process condition. Therefore, in recent exposure apparatuses, generally, 1
A plurality of illumination conditions can be implemented by one device, and an optimal illumination condition can be selected at the time of exposure.

[0003]

Incidentally, in order to enable a plurality of illumination conditions to be implemented by one device, the illumination conditions can be roughly classified into the following two methods. One is a method of arranging and switching a plurality of aperture stops in a position conjugate to the position of the aperture stop of the projection optical system in the illumination optical device. The position conjugate with the position of the aperture stop of the projection optical system in the illumination optical device here is hereinafter referred to as a pseudo light source position. This is because, when the illumination optical system realizes a Koehler illumination optical system, this pseudo light source position can be considered as a light source position. According to this method, the light intensity distribution at the position of the pseudo light source can be changed, and a plurality of illumination conditions can be achieved. Hereinafter, this method is referred to as method 1.

[0004] Method 1 includes, for example, circular, annular, bipolar,
It is used when performing deformed illumination using an aperture stop having a pole shape or the like. FIG. 8 shows an example of the shape of the illumination field when such modified illumination is performed. FIG. 8A shows a circle,
FIG. 8B shows an example of an illumination field in the case of using a ring zone, and FIG. The shaded area in the figure is the territory. The dotted line in FIG. 8C is an auxiliary line for indicating that the four poles are on the same annular zone.

Another method is to switch the optical system between the light source and the pseudo light source position, or to arrange a zoom optical system between the light source and the pseudo light source position to perform zooming. With this method, the shape of the light beam at the position of the pseudo light source can be made a predetermined shape, and a plurality of illumination conditions can be achieved. Hereinafter, this method is referred to as method 2.

However, both methods 1 and 2 have the following disadvantages. In the method 1, a plurality of aperture stops having a predetermined shape are prepared and switched to be used. However, as mentioned above, the selection of illumination conditions is a very important factor in the photolithography process, and it is necessary to change the illumination conditions for each pattern and process condition in a very fine manner to select the optimal illumination conditions. Is required. For this purpose, it is preferable that the lighting conditions can be changed continuously.
If only a circular aperture is considered, it is possible to make the diameter continuously variable, and such a diaphragm is actually used in a camera or the like. However, in practice, not only a circular aperture but also an aperture stop having the above-described existing shape and an aperture stop having another shape are required, and further, it is required that their sizes can be continuously changed. On the other hand, in the apparatus of Method 1, only the aperture prepared in advance can be used, so that the lighting conditions can be changed finely,
It is extremely difficult to change continuously, and it is becoming impossible to meet the demands of the latest equipment. In addition, there is a problem that light efficiency is poor because light is blocked by the aperture.

[0007] In the method 2, switching the optical system has a drawback in that it cannot cope with a minute change in illumination conditions as in the case of switching the aperture in the method 1. In the case of using a zoom optical system, a large number of general characteristics of the zoom optical system such as a complicated optical system, an increase in the number of lenses, a decrease in the amount of light, an increase in device deterioration speed, an increase in weight, etc. There is a problem and it cannot be said that it is suitable for an exposure apparatus. In recent years, particularly with the shortening of the exposure wavelength, the acceleration of the deterioration rate of the apparatus due to the temporal change of the transmittance of the lens is becoming a serious problem.

The present invention has been made in view of such a problem, and an object of the present invention is to provide an illumination optical device with high light efficiency capable of continuously changing illumination conditions without using a zoom optical system. An exposure apparatus provided with the illumination optical apparatus, and a method for manufacturing a micro device using the exposure apparatus.

[0009]

According to a first aspect of the present invention, there is provided an optical integrator for uniformly illuminating a surface to be irradiated based on light from a light source.
Light conversion means disposed in an optical path between the light source and the optical integrator, for converting a cross-sectional shape of light from the light source into a desired shape or a desired size, the light conversion means comprising: There is provided an illumination optical device including an optical element having a number of minute reflecting surfaces arranged in an array. Here, if each minute reflecting surface is arranged at a predetermined angle in a predetermined direction, the light beam can be divided into minute units for each reflecting surface and deflected in a predetermined direction by a predetermined angle. Thereby, the cross-sectional shape of the light beam incident on the optical integrator can be converted into a desired shape or a desired size, and a desired light intensity distribution can be formed on the optical integrator. In addition, since all light from the light source can be used without being blocked, high light efficiency can be achieved.

According to a preferred aspect of the first invention, one or all of the plurality of minute reflecting surfaces are configured to be movable, and the sectional shape of light from the light source is changed to a desired shape or a desired size. And a control means for controlling the movement of a part or all of the plurality of minute reflecting surfaces in order to convert the light into the light. According to this configuration, by controlling the minute reflecting surface, the cross-sectional shape or the size of the light beam incident on the optical integrator can be variously converted, and various illumination conditions can be achieved with one exposure apparatus. Can be. If the movement of the reflecting surface is configured to be continuously changeable, it is possible to continuously change the illumination conditions without using the zoom optical system.

According to a preferred aspect of the first invention,
At least one of the inclination angle and the inclination direction of one or all of the plurality of minute reflection surfaces is configured to be changeable. By considering both the tilt angle and the tilt direction as the change parameters, it is possible to change the illumination conditions in various ways.

According to a preferred aspect of the first invention,
At least one of the plurality of minute reflecting surfaces is non-planar. As the non-planar surface shape, various surface shapes such as a concave surface, a convex surface, a spherical surface, an elliptical surface, a paraboloid, and the like can be considered.
According to this configuration, each of the light beams divided into minute units can have convergence or divergence.
Thus, light can be more freely converted, and more diverse lighting conditions can be achieved.

As the light conversion means as described above, for example, a DMD (Dig) developed by Texas Instruments
ital Micromirror Device)
(Trademark) can be used. The DMD is an element in which a number of micro-reflection mirrors are arranged in a grid pattern on a substrate, and the inclination of each mirror is individually controlled.

According to a second aspect of the present invention, there is provided the illumination optical device described above, a mask holding means for setting a mask having a predetermined pattern on the surface to be illuminated, and a pattern image of the mask on a photosensitive substrate. And a substrate holding means for holding the photosensitive substrate. According to such a configuration, it is possible to provide an exposure apparatus capable of finely changing illumination conditions for each pattern or process condition, and performing exposure under optimum illumination conditions.

According to a third aspect of the present invention, there is provided an exposure step of exposing a pattern formed on the mask onto the substrate using the exposure apparatus described above, and a step of exposing the substrate exposed in the exposure step. And a developing step of developing the microdevice. According to such a configuration, the pattern can be exposed under the optimum illumination condition, so that the pattern can be formed well and the yield of the product can be improved.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the following description and the accompanying drawings, components having substantially the same functions and configurations are denoted by the same reference numerals, and redundant description will be omitted. FIG. 1 is a schematic configuration diagram of an exposure apparatus according to a first embodiment of the present invention. A schematic configuration of the present exposure apparatus will be described with reference to FIG.

The light beam emitted from the light source 1 enters the relay optical system 2. The relay optical system 2 may constitute a collimating optical system. In this case, the light beam is converted into parallel light and emitted. Thereafter, the light beam enters the movable multi-mirror 3. The movable multi-mirror 3 is composed of elements having a large number of minute reflecting surfaces arranged in an array. The movable multi-mirror 3 may be constituted by, for example, a DMD, and has a function as a light beam conversion element here, as described later in detail.

The light beam emitted from the movable multi-mirror 3 is
The light enters a fly-eye lens 5 as an optical integrator via a relay optical system 4. Here, the movable multi-mirror 3 is arranged at the front focal position of the relay optical system 4, but this arrangement is not necessarily limited. The relay optical system 4 has a function of transmitting the light beam converted by the movable multi-mirror 3 to the fly-eye lens 5. Although the fly's eye lens 5 is arranged here at the above-described pseudo light source position, this arrangement is not necessarily limited, and may be arranged at a position defocused from the pseudo light source position. Fly-eye lens 5
It is constituted by arranging a large number of lens elements two-dimensionally. The light beam incident on the fly-eye lens 5 is two-dimensionally split by the multiple lens elements, and forms a large number of light source images on the rear focal plane of the fly-eye lens 5.

After passing through the condenser optical system 6, the light beams from the multiple light source images are limited by the field stop FS. The field stop FS defines the field of view at the time of exposure. Thereafter, the light beam passes through the condenser optical system 7 and the turning mirror M1, and uniformly illuminates the mask 8 on which a predetermined circuit pattern is formed. The luminous flux transmitted through the mask 8 is
Through the projection optical system 9, the wafer reaches a wafer 10, which is a substrate on which a resist is applied, and a circuit pattern of a mask 8 is formed on the wafer 10. AS in the figure is an aperture stop position of the projection optical system. Here, the mask 8 is held on a mask stage (not shown), and the wafer 10 is held on a wafer stage (not shown). Both the mask stage and the wafer stage can be moved two-dimensionally, and by moving the mask 8 and the wafer 10 in a predetermined direction via the mask stage and the wafer stage, the pattern on the entire surface of the mask 8 changes the projection optical system 9. The wafer is transferred and exposed on the wafer 10.

Next, the movable multi-mirror 3 will be described in detail. FIG. 2 shows a partial perspective view of the movable multi-mirror 3. As shown in FIG. 2, the movable multi-mirror 3 includes a large number of minute element mirrors 30 laid with the flat reflecting surface as the upper surface. The hatched lines in the figure represent the side surfaces of the element mirror 30. Each element mirror 30 is movable, and its tilt angle and tilt direction are individually driven and controlled by a control system (not shown). Here, the outer shape of the element mirror 30 is a square, but it is not limited to this. However, from the viewpoint of light use efficiency, a shape that can be arranged without gaps is preferable.
Further, it is preferable that the interval between the adjacent element mirrors 30 is set to a necessary minimum. Furthermore, it is preferred that the element mirror 30 be as small as possible, in order to allow fine changes in the lighting conditions.

Next, an example of a driving mechanism of the movable multi-mirror 3 will be described with reference to FIG. FIG. 3 is a perspective view showing a schematic configuration of the driving mechanism. As shown in FIG. 3, the element mirror 30 has the reflecting surface facing upward and the hinge member 3
2 supported. The major axis direction of the hinge member 32 coincides with the diagonal direction of the element mirror 30, and four electrodes 34 project from the hinge member 32 along a direction orthogonal to the major axis direction and parallel to the reflection surface. I have. Both ends of the hinge member 32 are swingably supported at the upper end of the support member 36 with the direction coinciding with the long axis direction as the swing axis direction. The support member 36 is provided on a substrate 38. Four electrodes 40 are formed on the substrate 38 at positions respectively corresponding to the four electrodes 34.

By applying a potential difference between the corresponding electrodes 34 and 40, the hinge member 32 can be swung by an electrostatic force acting on the basis of the potential difference between the electrodes. As the hinge member 32 swings, the element mirror 30 supported by the hinge member 32 also swings. By using such means, the inclination angle and the inclination direction of the element mirror 30 can be electrically easily controlled. Here, one element mirror 30 has been described as an example.
Has the same configuration. FIG. 4 is a cross-sectional view showing a state in which a plurality of element mirrors 30 and the aforementioned driving mechanism are arranged on a substrate.

The light incident on the movable multi-mirror 3 is split in units of the element mirrors 30, and is deflected at a predetermined angle in a predetermined direction according to the tilt direction and the tilt angle of each element mirror 30. By controlling the movement of each of the element mirrors 30 and setting them so as to have a predetermined inclination direction and inclination angle, the light beam emitted from the movable multi-mirror 3 can be freely controlled. That is, the movable multi-mirror 3 functions as a light beam conversion element that can convert the cross-sectional shape of the light beam into a desired shape and size. Therefore, a light beam having a desired light intensity distribution can be formed on the fly-eye lens 5 by the movable multi-mirror 3. Here, each element mirror 3
If it is configured so that the movement of 0 can be changed continuously,
The lighting conditions can be changed continuously. For example, circular illumination used in conventional exposure equipment,
It is possible to achieve modified illumination such as two poles or four poles, and it is also possible to continuously change the size of the illumination field in each illumination.

According to the present embodiment, the following many effects can be obtained by disposing the movable multi-mirror 3 in the optical path between the light source 1 and the fly-eye lens 5 as described above. It is possible to form a light beam having a desired light intensity distribution on the fly-eye lens 5, and it is possible to cope with various types of deformed illumination. Moreover, since the light flux can be changed continuously, the illumination conditions can be changed continuously. In addition, since a single movable multi-mirror can form various light flux shapes, there is no need to prepare a plurality of apertures required in an exposure apparatus that switches a plurality of apertures in the related art.
Further, since the shape of the light beam can be changed without blocking light by the stop, high light efficiency can be obtained. Furthermore, since a zoom optical system is not required, various problems caused by the zoom optical system can be avoided, the number of parts is small, and the apparatus can be made compact and cost can be reduced. Further, since the shape of the light beam can be converted by electrical means, the control is easy, and it is possible to immediately respond to changes in patterns and process conditions.

Next, a modified example of the movable multi-mirror 3 will be described. In this modification, only the configuration of the element mirror is different.
Other drive mechanisms are the same as those described above. FIG. 5 shows a sectional view of this modification. Here, the reflection surface of the element mirror 31 is a concave spherical surface. By adopting such a configuration, it is possible to impart convergence or divergence to the luminous flux split in units of the element mirror 31. This works independently of the relay optical system 4, so that the degree of freedom of light beam conversion is increased and more various illumination conditions can be achieved. For example, the light split by the unit mirror 31 can be made to have a predetermined spread on the incident surface of the fly-eye lens 5, which is obtained by disposing the fly-eye lens 5 from a normal position to a defocus position. Substantially the same effect as described above can be obtained.

The shape of the reflecting surface of the element mirror is not limited to the above example. It may be a convex shape, and it is preferable to select an optimum shape such as an elliptical surface, a parabolic surface, or an arbitrary curved surface according to a use or an apparatus.

FIG. 6 is a schematic configuration diagram of an exposure apparatus according to a second embodiment of the present invention. A major difference from the first embodiment is that an internal reflection type rod integrator is used as an optical integrator. Hereinafter, the second embodiment will be described while paying attention to this point.

The optical system from the light source 1 to the movable multi-mirror 3 is the same as in the first embodiment, and the description is omitted. The light beam emitted from the movable multi-mirror 3 enters a rod integrator 15 as an optical integrator via a relay optical system 14. Here, the relay optical system 14 is arranged such that the movable multi-mirror 3 and the incident surface of the rod integrator 15 have a conjugate relationship. Note that this arrangement is not limited, and it is sufficient that the arrangement is such that the diameter of the light beam incident on the rod integrator 15 does not exceed the effective diameter of the rod integrator 15. Alternatively, when the light quantity loss is not a problem, it is not necessary to consider the incident light beam diameter and the effective diameter, and they may be arranged at almost positions.

The rod integrator 15 is a hollow reflective integrator having a reflective film formed on the inner surface, or an inner reflective glass rod. Rod integrator 15
Is incident on the exit end face without being reflected or reflected on the inner face, and the inside of the exit end face is uniformly illuminated. After that, the light beam passes through the condenser optical system 17 and the return mirror M1, and uniformly illuminates the mask 8 on which a predetermined circuit pattern is formed. Here, the condenser optical system 17 is arranged so that the exit end face of the rod integrator 15 and the mask 8 have a conjugate relationship. This arrangement requires a certain degree of rigor to ensure uniformity of illuminance for illuminating the mask 8. The light beam transmitted through the mask 8 reaches a wafer 10 as a substrate coated with a resist via a projection optical system 9, and a circuit pattern of the mask 8 is formed on the wafer 10.

Here, the configuration of the movable multi-mirror 3 is the first
This is the same as the embodiment. Also in this embodiment,
The movable multi-mirror 3 can convert the cross-sectional shape of the light beam from the light source into a desired shape and size so that the light beam incident on the rod integrator 15 has a desired light intensity distribution. Therefore, it is possible to cope with various types of modified illumination, and it is possible to continuously change the illumination conditions, and the same effect as in the first embodiment can be obtained. In each of the above embodiments, an example is described in which a fly-eye lens or a facing reflection type optical member is used as an optical integrator. However, the present invention is not limited to these, and for example, a diffractive optical element, a micro lens eye, or the like may be used. It can be used as an integrator.

FIG. 7 is a flowchart showing an example of an operation when manufacturing a micro device using the above-described exposure apparatus. Here, a reticle is used instead of the mask 8 described above. First, in step 101, a metal film is deposited on one lot of wafers 10. In the next step 102, a photoresist is applied on the metal film on the wafer 10 of the lot. Thereafter, in step 103, the image of the pattern on the reticle is sequentially exposed and transferred to each shot area on the wafer 10 of the lot through the projection optical system 9 using the exposure apparatus.
Thereafter, in step 104, the photoresist on the one lot of wafers 10 is developed, and then in step 105, etching is performed on the one lot of wafers 10 using the resist pattern as a mask, so that the reticle is etched. A circuit pattern corresponding to the pattern is formed in each shot area on each wafer. After that, a circuit pattern of a further upper layer is formed.
As described above, a device such as a semiconductor element having an extremely fine circuit is favorably manufactured.

Although the preferred embodiments of the present invention have been described with reference to the accompanying drawings, it is needless to say that the present invention is not limited to such examples. It is clear that a person skilled in the art can conceive various changes or modifications within the scope of the technical idea described in the claims, and it is obvious that the technical scope of the present invention is not limited thereto. It is understood that it belongs to.

In the above example, the movable multi-mirrors 3 are individually movable. However, the present invention is not limited to this, and a part of the movable multi-mirrors 3 may be movable. Further, the whole or a part of the movable multi-mirror 3 may be configured such that only one of the tilt angle and the tilt direction is movable.

[0034]

As described above, according to the present invention, it is possible to provide an illumination optical device which can continuously change illumination conditions without using a zoom optical system and has high light efficiency. Further, it is possible to finely change the illumination conditions for each pattern or process condition, and to provide an exposure apparatus capable of performing exposure under suitable illumination conditions. Further, it is possible to provide a method for manufacturing a micro device capable of favorably manufacturing a device under suitable lighting conditions.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an exposure apparatus according to a first embodiment of the present invention.

FIG. 2 is a partial perspective view of a movable multi-mirror.

FIG. 3 is a perspective view illustrating a configuration of a driving mechanism of an element mirror.

FIG. 4 is a cross-sectional view showing a state where a plurality of element mirrors and a driving mechanism are arranged.

FIG. 5 is a sectional view showing a modification of the movable multi-mirror.

FIG. 6 is a schematic configuration diagram of an exposure apparatus according to a second embodiment of the present invention.

FIG. 7 is a flowchart illustrating an example of a method for manufacturing a micro device according to an embodiment of the present invention.

FIG. 8 is a diagram illustrating an illumination field formed when aperture stops having different shapes are used.

[Explanation of symbols]

 Reference Signs List 1 light source 2, 4 relay optical system 3 movable multi-mirror 4 vibrating mirror 5 fly-eye lens 6, 7 condenser optical system 8 mask 9 projection optical system 10 wafer 30, 31 element mirror 32 hinge member 34, 40 electrode 36 support member 38 substrate FS Field stop M1 folding mirror

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03F 7/20 521 H01L 21/30 515D G02B 27/00 E

Claims (6)

[Claims] An optical integrator for uniformly illuminating a surface to be illuminated based on light from a light source, and an optical integrator disposed in an optical path between the light source and the optical integrator, wherein a cross-sectional shape of the light from the light source is desired. A light converting means for converting the light into a desired shape or a desired size, wherein the light converting means includes an optical element having a large number of minute reflecting surfaces arranged in an array. . 2. A method according to claim 1, wherein a part or all of said plurality of minute reflecting surfaces are movable, and convert a sectional shape of light from said light source into a desired shape or a desired size.
The illumination optical device according to claim 1, further comprising a control unit configured to control a movement of a part or all of the plurality of minute reflecting surfaces. 3. A part or all of the plurality of minute reflecting surfaces are configured such that at least one of an inclination angle and an inclination direction is changeable. 3. The illumination optical device according to 2. 4. The illumination optical device according to claim 1, wherein at least one of the plurality of minute reflecting surfaces is non-planar. 5. The illumination optical device according to claim 1, a mask holding means for setting a mask having a predetermined pattern on the surface to be irradiated, and a pattern image of the mask. An exposure apparatus comprising: a projection optical system that projects onto a photosensitive substrate; and substrate holding means that holds the photosensitive substrate. 6. An exposure step of exposing a pattern formed on the mask onto the substrate using the exposure apparatus according to claim 5, and a development step of developing the substrate exposed in the exposure step. A method for manufacturing a micro device, comprising: