JP2003015314A - Illumination optical device and exposure device provided with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an illumination optical device for carrying out deformed illumination while suppressing the loss of a light quantity satisfactorily even to light of a short wavelength with a simple structure having a small number of optical members. SOLUTION: The illumination optical device is provided with a light source means (1) for supplying almost parallel luminous flux, a first luminous flux conversion device (4) for converting the almost parallel luminous flux from the light source means into divergent luminous flux having a predetermined cross-sectional shape, a second luminous flux conversion device (5) for converting the divergent luminous flux from the first luminous flux conversion device into almost parallel luminous flux, an optical integrator (9) for forming a large number of light sources on the basis of the luminous flux through the second luminous flux conversion device, and an optical guiding optical system (10) for guiding the luminous flux from the large number of light sources to a surface (M) to be irradiated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illumination optical device and an exposure apparatus equipped with the illumination optical device, and more particularly for manufacturing microdevices such as semiconductor devices, image pickup devices, liquid crystal display devices and thin film magnetic heads in a lithography process. The present invention relates to an illumination optical device suitable for the exposure apparatus.

[0002]

2. Description of the Related Art In a typical exposure apparatus of this type,
The light flux emitted from the light source enters the fly-eye lens,
A secondary light source including a large number of light sources is formed on the rear focal plane. The light flux from the secondary light source is incident on the condenser lens after being limited through an aperture stop arranged near the rear focal plane of the fly-eye lens. The aperture stop limits the shape or size of the secondary light source to the desired shape or size according to the desired illumination condition (exposure condition).

The light beam condensed by the condenser lens illuminates the mask on which a predetermined pattern is formed in a superimposed manner. The light transmitted through the mask pattern forms an image on the wafer via the projection optical system. Thus, on the wafer,
The mask pattern is projected and exposed (transferred). Since the pattern formed on the mask is highly integrated, it is essential to obtain a uniform illuminance distribution on the wafer in order to accurately transfer this fine pattern onto the wafer.

In recent years, by changing the size of the aperture (light transmitting portion) of the aperture stop arranged on the exit side of the fly-eye lens, the coherency of the illumination σ (σ
Value = aperture stop diameter / projection optical system pupil diameter, or σ value = illumination optical system exit side numerical aperture / projection optical system incident side numerical aperture)
The technique of changing the is attracting attention. Further, by setting the shape of the aperture of the aperture stop arranged on the exit side of the fly-eye lens to be a ring shape or a four-hole shape (that is, a quadrupole shape), the secondary light source formed by the fly-eye lens A technique for limiting the shape to a ring shape or a quadrupole shape to improve the depth of focus and resolution of the projection optical system has been attracting attention.

In this case, in order to perform modified illumination (annular illumination or quadrupole illumination) by limiting the shape of the secondary light source to an annular or quadrupole shape, a relatively large secondary formed by a fly-eye lens. If the light flux from the light source is simply limited by an aperture stop having an annular or quadrupole opening, a considerable part of the light flux from the secondary light source is blocked by the aperture stop and does not contribute to illumination (exposure). As a result, the illuminance on the mask and the wafer is reduced due to the loss of light amount at the aperture stop, and the throughput of the exposure apparatus is also reduced. Therefore, a configuration has been proposed in which an annular or quadrupole secondary light source is formed based on an annular or quadrupole light beam formed via a diffractive optical element or an axicon.

[0006]

However, in the conventional illumination optical device for performing the modified illumination using the diffractive optical element or the axicon, the number of optical members is increased and the configuration is complicated, which leads to the enlargement of the device. There was an inconvenience. Further, in order to improve the resolving power of the exposure apparatus, for example, when using exposure light having a wavelength of 200 nm or less, if the number of optical members is large, there is a disadvantage that light amount loss easily occurs on the lens surface and inside the optical member. there were.

The present invention has been made in view of the above-mentioned problems, and based on a simple structure in which the number of optical members is small, it is possible to suppress light quantity loss even for light of a short wavelength and perform modified illumination. It is an object of the present invention to provide an illuminating optical device that can be performed and an exposure apparatus including the illuminating optical device. Further, the present invention uses an exposure apparatus capable of performing modified illumination by appropriately suppressing the light amount loss even for light of a short wavelength,
An object of the present invention is to provide a microdevice manufacturing method capable of manufacturing a good microdevice under a good illumination condition.

[0008]

In order to solve the above-mentioned problems, in a first invention of the present invention, in an illumination optical device for illuminating a surface to be illuminated, a light source means for supplying a substantially parallel light beam, and the light source. A first light flux conversion element for converting the substantially parallel light flux from the means into a divergent light flux having a predetermined cross-sectional shape, and a second light flux conversion for converting the divergent light flux from the first light flux conversion element into a substantially parallel light flux. And an element, wherein the first light flux conversion element has a diffractive optical element or a microlens array.

According to a preferred aspect of the first invention, in order to change the size of the cross-sectional shape of the substantially parallel light flux formed through the second light flux conversion element, the second light flux conversion element is placed on the optical axis. It further comprises drive means for moving along. Further, it is preferable that the second light flux conversion element has a conical prism having a flat surface on one side and a conical surface on the other side. Furthermore, a variable power optical system further arranged in the optical path between the light source means and the first light flux conversion element or in the optical path between the second light flux conversion element and the illuminated surface is provided. Is preferred.

According to a preferred aspect of the first invention,
It further comprises an optical integrator for forming a large number of light sources based on the light beams that have passed through the second light beam conversion element, and a light guide optical system for guiding the light beams from the plurality of light sources to the irradiation surface. There is. In this case, the variable power optical system arranged in the optical path between the second light beam conversion element and the illuminated surface is arranged in the optical path between the second light beam conversion element and the optical integrator. Is preferred.

A second invention of the present invention comprises the illumination optical device of the first invention, and a projection optical system for projecting and exposing the mask pattern set on the irradiated surface onto a photosensitive substrate. An exposure apparatus characterized by the above.

In a third aspect of the present invention, an exposure step of exposing the pattern of the mask on the photosensitive substrate by the exposure apparatus of the second aspect of the invention, and a developing step of developing the photosensitive substrate exposed by the exposure step A method of manufacturing a microdevice, comprising:

[0013]

DETAILED DESCRIPTION OF THE INVENTION According to a typical embodiment of the present invention,
For example, the parallel light flux from the light source means is converted into an annular divergent light flux via a first light flux conversion element such as a diffractive optical element. Then, a second light beam conversion element such as a conical prism converts the annular divergent light beam from the diffractive optical element into an annular parallel light beam. Furthermore, by an optical integrator such as a fly-eye lens, based on the annular parallel light flux from the conical prism,
An annular secondary light source is formed on the illumination pupil plane. A light flux from a secondary light source in the form of an annular zone formed on the illumination pupil plane illuminates a surface to be illuminated such as a mask in a superimposed manner via a light guide optical system.

As described above, according to the present invention, the combination of the diffractive optical element as the first light beam conversion element and the conical prism as the second light beam conversion element allows the predetermined cross-sectional shape (for example, annular shape, 4 A polar light flux is formed. Therefore, in the exposure apparatus including the illumination optical device of the present invention, even if the exposure light having a short wavelength is used to improve the resolution, the light quantity loss is well suppressed based on the simple configuration with a small number of optical members. Deformed illumination can be performed. Further, based on the modified illumination in which the light amount loss is well suppressed, it is possible to manufacture a good microdevice with high throughput and high resolution.

Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a diagram schematically showing a configuration of an illumination optical device according to the first embodiment of the present invention. Referring to FIG. 1, the illumination optical device of the first embodiment uses, as a light source 1 for supplying illumination light, an ArF excimer laser light source for supplying light having a wavelength of 193 nm, or 157.
An F ₂ laser light source that supplies light with a wavelength of nm is provided. The parallel light flux emitted from the light source 1 has a rectangular cross section elongated in a direction perpendicular to the paper surface of FIG. 1, and enters a beam expander 2 including a pair of lenses 2a and 2b.

Each of the lenses 2a and 2b has a negative refracting power and a positive refracting power in the plane of FIG. Therefore, the light beam incident on the beam expander 2 is expanded in the plane of the paper of FIG. 1 and shaped into a light beam having a cross section of a predetermined shape. The parallel light flux that has passed through the beam expander 2 as a shaping optical system enters the afocal zoom lens 3. The afocal zoom lens 3 is a variable power optical system configured to be capable of continuously changing the magnification within a predetermined range while maintaining the afocal system (afocal optical system).

The change in magnification of the afocal zoom lens 3 is performed by the first drive system 21 which operates based on a command from a control system (not shown). The parallel luminous flux whose cross-sectional shape is enlarged or reduced according to its magnification through the afocal zoom lens 3 is a diffractive optical element (D
OE) 4. The diffractive optical element 4 is formed, for example, by forming a step having a pitch on the order of the wavelength of illumination light on a glass substrate, and has a function of diffracting an incident beam to a desired angle.

FIG. 2 is a view for explaining the action of the diffractive optical element for the ring zone in the first embodiment. Referring to FIG. 2, the diffractive optical element 4 for an annular zone radially diverges a vertically incident thin luminous flux according to one predetermined divergence angle, and converts it into a divergent luminous flux having an annular cross section with a narrow width. . Therefore, since a plurality of thin light fluxes are adjacent to each other to form one parallel light flux, the parallel light fluxes vertically incident on the diffractive optical element 4 are superimposed and converted into a wide annular divergent light flux. Thus, the diffractive optical element 4 constitutes a first light flux conversion element for converting the parallel light flux from the light source 1 into a divergent light flux having a predetermined cross-sectional shape.

The diffractive optical element 4 is constructed so that it can be inserted into and removed from the illumination optical path and can be switched to the diffractive optical element 40 for four poles. Diffractive optical element 4 for 4 poles
The configuration and operation of 0 will be described later. Here, switching between the diffractive optical element 4 for the ring zone and the diffractive optical element 40 for the four poles is performed by the second drive system 22 that operates based on a command from the control system.

The annular divergent light beam formed via the diffractive optical element 4 enters the conical prism 5. The conical prism 5 has a light source side surface (a surface on the left side in FIG. 1) 5a formed in a flat shape, and a surface on the irradiated surface side (a surface on the right side in FIG. 1).
5b is formed in a conical convex shape toward the surface to be illuminated. More specifically, the refracting surface 5b on the irradiated surface side of the conical prism 5 is configured to have a shape corresponding to a conical surface (side surface excluding the bottom surface) of a cone that is symmetrical with respect to the optical axis AX.

Therefore, when a zonal divergent light beam is incident on the conical prism 5, it is deflected at an equal angle about the optical axis AX and an annular parallel light beam is formed along the optical axis AX. The ring-shaped parallel light flux formed via the conical prism 5 forms a ring-shaped illumination area on the irradiated surface 6. In this way, the conical prism 5 constitutes a second light flux conversion element for converting the divergent light flux from the diffractive optical element 4 as the first light flux conversion element into a parallel light flux. The conical prism 5 is configured to be movable along the optical axis AX, and the optical axis A
The movement along X is performed by the third drive system 23 that operates based on a command from the control system. The illuminated surface 6 is arranged so that the incident surface of the fly-eye lens 9 coincides with it. The light fluxes from a large number of light sources formed on the rear focal plane of the fly-eye lens 9 are subjected to the condensing action of the condenser optical system 10, and then illuminate the mask M having a predetermined pattern in a superimposed manner.

FIG. 3 is a diagram for explaining changes in the annular illumination area and the annular illumination area formed by the action of the afocal zoom lens and the conical prism on the illuminated surface in the first embodiment. Further, FIG. 4 is a diagram for explaining the action of the conical prism. Referring to FIG. 3A, in the standard state of the afocal zoom lens 3 and the conical prism 5, the outer diameter φo, the inner diameter φi, and the width b.
An annular illumination area having is formed.

When the magnification of the afocal zoom lens 3 is changed by the action of the first drive system 21, the cross-sectional shape of the light beam incident on the diffractive optical element 4 changes in a similar manner according to the change in the magnification. . As a result, as shown in FIG. 3 (b), the average of the outer diameter φo and the inner diameter φi does not change, in other words, the center line c of the annular illumination area does not change, and the width b (and thus Outer diameter φo and inner diameter φi
It also changes according to the change in magnification of the afocal zoom lens 3.

On the other hand, when the conical prism 5 is moved along the optical axis AX by the action of the third drive system 23, as shown in FIG. 4, it is incident on the irradiated surface 6 in accordance with its movement amount and its direction. Both the outer diameter and the inner diameter of the ring-shaped light flux that changes are changed. As a result, as shown in FIG. 3C, the outer diameter φo and the inner diameter φi change at the same ratio according to the movement amount and the direction of the conical prism 5 without changing the width b.

FIG. 5 is a diagram for explaining the operation of the diffractive optical element for four poles in the first embodiment. Second drive system 22
When the diffractive optical element 40 for the four poles is positioned in the illumination optical path in place of the diffractive optical element 4 for the annular zone by the action of FIG.
As shown in FIG. 4, the thin light flux that has entered the diffractive optical element 40 becomes four small circular divergent light fluxes. Therefore, since thin light fluxes are formed adjacent to each other to form parallel light fluxes, the parallel light fluxes vertically incident on the diffractive optical element 40 are superimposed and converted into a large quadrupolar divergent light flux composed of four circular divergent light fluxes. Then, a quadrupole illumination region is formed on the irradiated surface 6 via the conical prism 5.

FIG. 6 is a view for explaining changes in the quadrupole illumination area formed on the illuminated surface and the quadrupole illumination area by the action of the afocal zoom lens and the conical prism in the first embodiment. is there. Referring to FIG. 6A, in the standard state of the afocal zoom lens 3 and the conical prism 5, the outer diameter φo, the inner diameter φi, and the width b.
A quadrupole illumination area having is formed. Here, the outer diameter φo and the inner diameter φi are the diameters of the circle circumscribing and the circle inscribing the quadrupole illumination region, respectively. Also, the width b
Is the diameter of each circular illumination area forming the quadrupole illumination area, and is defined as 1/2 of the difference between the outer diameter φo and the inner diameter φi.

When the magnification of the afocal zoom lens 3 is changed by the action of the first drive system 21, the cross-sectional shape of the light beam incident on the diffractive optical element 40 changes in a similar manner according to the change in the magnification. . As a result, as shown in FIG. 6B, the width b (and thus the outer diameter φo and the inner diameter φi) of the afocal zoom lens 3 changes without changing the center line c of the quadrupole illumination region. Change according to. On the other hand, due to the action of the third drive system 23, the conical prism 5
Is moved along the optical axis AX, as shown in FIG. 6C, the outer diameter φo and the inner diameter φ
i changes at the same ratio according to the amount of movement of the conical prism 5 and its direction.

FIG. 7 is a view schematically showing the arrangement of an exposure apparatus having an illumination optical device according to the second embodiment of the present invention. In FIG. 7, the Z axis is along the normal direction of the wafer which is the photosensitive substrate, the Y axis is in the direction parallel to the paper surface of FIG. 7 within the wafer surface, and the direction perpendicular to the paper surface of FIG. 7 within the wafer surface. The X axis is set for each. In FIG. 7, the illumination optical device is set to perform annular illumination.

The exposure apparatus of FIG. 7 has a light source 1 for supplying exposure light (illumination light), as in the first embodiment.
It is equipped with an ArF excimer laser light source that supplies light with a wavelength of 93 nm. A parallel light flux emitted from the light source 1 along the Z direction has a rectangular cross section elongated along the X direction and is incident on a beam expander 2 including a pair of lenses 2a and 2b. Beam expander 2
The light beam incident on is expanded in the plane of the paper of FIG. 1 (YZ plane) and shaped into a light beam having a predetermined rectangular cross section.

The parallel light beam that has passed through the beam expander 2 serving as a shaping optical system is deflected in the Y direction by the bending mirror, and then, through the afocal zoom lens 3, as in the first embodiment, for annular illumination. Is incident on the diffractive optical element 4. In the second embodiment, the diffractive optical element 4 is configured to be switchable between the diffractive optical element 40 for quadrupole illumination and the microlens array 41 for ordinary circular illumination.
The configuration and operation of the microlens array 41 for circular illumination will be described later.

The ring-shaped divergent light beam from the diffractive optical element 4 becomes a ring-shaped parallel light beam along the optical axis AX via the conical prism 5, and enters the microlens array 7.
Thus, a ring-shaped illumination field centered on the optical axis AX is formed on the incident surface of the microlens array 7. The microlens array 7 is an optical element including a large number of regular hexagonal or regular quadrangular microlenses having a positive refracting power that are vertically and horizontally densely arranged. In general, a microlens array is formed, for example, by subjecting a parallel flat glass plate to an etching treatment to form a group of microlenses.

Therefore, the light beam incident on the microlens array 7 is two-dimensionally divided by a large number of microlenses, and one light source is formed on the rear focal plane of each microlens. In this way, on the back focal plane of the microlens array 7, a ring-shaped substantially planar light source having a light intensity distribution almost the same as the illumination field formed by the incident light beam on the microlens array 7 is formed. In this way, the microlens array 7 constitutes a first optical integrator for forming a large number of light sources based on the light flux from the light source 1.

A light flux from a substantially ring-shaped surface light source formed on the back focal plane of the microlens array 7 is superposed on a fly-eye lens 9 as a second optical integrator via an imaging lens system 8. Light up. In addition,
The imaging lens system 8 optically connects the rear focal plane of the microlens array 7 and the exit surface of the fly-eye lens 9 in a substantially conjugate manner.

Therefore, the luminous fluxes from a large number of light sources formed on the rear focal plane of the microlens array 7 are directed to the rear focal plane of the imaging lens system 8 and eventually to the fly-eye lens 9.
A ring-shaped illumination field centered on the optical axis AX is formed on the incident surface of. The fly-eye lens 9 is configured by arranging a large number of lens elements having a positive refractive power vertically and horizontally and densely. Each lens element forming the fly-eye lens 9 has a rectangular cross section similar to the shape of the illumination field to be formed on the mask (and the shape of the exposure area to be formed on the wafer).

Therefore, the light beam incident on the fly-eye lens 9 is two-dimensionally divided by a large number of lens elements, and a large number of light sources are respectively formed on the rear focal planes of the lens elements on which the light beam is incident. Thus, the fly-eye lens 9 is attached to the rear focal plane of the fly-eye lens 9.
A substantially ring-shaped surface light source (hereinafter, referred to as “secondary light source”) having a light intensity distribution substantially the same as the illumination field formed by the incident light flux is formed.

The light flux from the annular secondary light source formed on the rear focal plane of the fly-eye lens 9 is restricted through an aperture stop (not shown) arranged in the vicinity thereof, and the condenser optical system 10 After receiving the light condensing function, the mask M on which a predetermined pattern is formed is superimposedly illuminated. As described above, in the second embodiment, the light source 1 to the condenser optical system 10 constitute an illumination optical device for illuminating the mask M as the illuminated surface.

The light flux that has passed through the pattern of the mask M forms an image of the mask pattern on the wafer W, which is a photosensitive substrate, via the projection optical system PL. In this manner, by performing batch exposure or scan exposure while two-dimensionally drivingly controlling the wafer W in a plane (XY plane) orthogonal to the optical axis AX of the projection optical system PL, a mask is formed in each exposure region of the wafer W. The M patterns are sequentially exposed.

In the collective exposure, so-called step
The mask pattern is collectively exposed to each exposure area of the wafer according to the and repeat method. In this case, the shape of the illumination area on the mask M is a rectangular shape close to a square, and the cross-sectional shape of each lens element of the fly-eye lens 9 is also a rectangular shape close to a square. On the other hand, in scan exposure, according to a so-called step-and-scan method, a mask pattern is scan-exposed to each exposure region of the wafer while moving the mask and the wafer relative to the projection optical system. In this case, the shape of the illumination area on the mask M has a ratio of short sides to long sides of, for example, 1: 3.
And the cross-sectional shape of each lens element of the fly-eye lens 9 is also similar to this.

In the annular illumination of the second embodiment, the illumination pupil plane, that is, the rear focal plane of the fly-eye lens 9 is shown in FIG.
An annular secondary light source is formed as shown in FIG. Therefore, when the magnification of the afocal zoom lens 3 is changed by the action of the first drive system 21, the center line c of the ring-shaped secondary light source does not change, as shown in FIG.
The width b (and thus the outer diameter φo and the inner diameter φi) changes according to the magnification change of the afocal zoom lens 3. When the conical prism 5 is moved along the optical axis AX by the action of the third drive system 23, as shown in FIG.
The outer diameter φo and the inner diameter φi change at the same ratio according to the movement amount and the direction of the conical prism 5 without changing the width b.

Next, in order to perform quadrupole illumination in the second embodiment, the diffractive optical element 40 for quadrupole illumination is illuminated by the action of the second drive system 22 in place of the diffractive optical element 4 for annular illumination. Position in the optical path. In this case, a quadrupole secondary light source as shown in FIG. 6A is formed on the illumination pupil plane, that is, the back focal plane of the fly-eye lens 9. Therefore, when the magnification of the afocal zoom lens 3 is changed by the action of the first drive system 21, the center line c of the quadrupole secondary light source does not change, as shown in FIG. 6B.
The width b (and thus the outer diameter φo and the inner diameter φi) changes according to the magnification change of the afocal zoom lens 3. When the conical prism 5 is moved along the optical axis AX by the action of the third drive system 23, as shown in FIG.
Without changing the width b of the quadrupole secondary light source, the outer diameter φo
And the inner diameter φi changes at the same ratio according to the moving amount of the conical prism 5 and its direction.

Next, in order to perform circular illumination in the second embodiment, circular illumination is performed by the action of the second drive system 22 instead of the diffractive optical element 4 for annular illumination or the diffractive optical element 40 for quadrupole illumination. The microlens array 41 for use is positioned in the illumination optical path. In this case, the microlens array 4
Reference numeral 1 denotes an optical element composed of a large number of square-shaped minute lenses having a positive refracting power which are densely arranged in the vertical and horizontal directions. Therefore, a substantially square surface light source is formed on the rear focal plane of the microlens array 7, and a square secondary light source is also formed on the rear focal plane (illumination pupil plane) of the fly-eye lens 9. It

The light flux from the square-shaped secondary light source is restricted through a circular aperture stop having a circular opening (light transmitting portion), and then is passed through a condenser optical system 10 to a mask M.
Are illuminated in a superimposed manner. Then, when the magnification of the afocal zoom lens 3 is changed by the action of the first drive system 21 or the conical prism 5 is moved along the optical axis AX by the action of the third drive system 23, a square-shaped secondary The size of the light source changes according to the magnification change of the afocal zoom lens 3 or the movement amount and direction of the conical prism 5.

As described above, in the second embodiment, the diffractive optical element 4 (40) and the conical prism 5 are combined to form a parallel light flux having a predetermined cross-sectional shape required for modified illumination. The shape and size of the secondary light source formed on the illumination pupil plane can be changed by the action of the afocal zoom lens 3 and the action of the conical prism 5. Here, it is clear that the afocal zoom lens 3 has a relatively simple structure. Therefore, even if exposure light with a short wavelength (light with a wavelength of 193 nm in the second embodiment) is used to improve the resolution, it is possible to satisfactorily suppress the loss of light quantity and vary it based on the simple configuration with a small number of optical members. Various modified illumination can be performed.

In the second embodiment described above, two optical integrators (microlens array 7 and fly-eye lens 9) are used, but as shown in FIG. 1, the arrangement of the microlens array 7 and the imaging lens system 8 is arranged. Alternatively, the light flux from the conical prism 5 may be directly guided to the fly-eye lens 9. As described above, the reason why the light flux from the conical prism 5 can be directly guided to the fly-eye lens 9 in the first and second embodiments is that the diffractive optical element 4 or the micro-lens array 41 for circular illumination is used.
However, since the light fluxes are overlapped to form a ring-shaped, quadrupole-shaped, or circular illumination cross-sectional shape, uneven light amount (unevenness unevenness) is small. On the other hand, using a prism, an annular shape, 4
Forming a polar or circular illumination cross-sectional shape is not preferable because light from a light source having uneven light quantity appears as uneven light quantity. A method using two optical integrators is advantageous in order to secure more uniform illuminance.

Further, in the above-described second embodiment, the microlens array 41 is positioned in the illumination optical path at the time of circular illumination, but the invention is not limited to this, and the diffractive optical element 42 for circular illumination may be used. It can also be used. FIG. 8 is a diagram illustrating the operation of the diffractive optical element for circular illumination that can be used in the second embodiment. Referring to FIG. 8, a circular divergent light beam is formed via the diffractive optical element 42 for circular illumination. In this case, the circular divergent light flux from the diffractive optical element 42 is converted into a circular parallel light flux via the conical prism 5, and a circular divergent light flux is applied to the illumination pupil plane (the rear focal plane of the fly-eye lens 9). A secondary light source is formed.

As another method of performing circular illumination, the diffractive optical element 4 for a ring zone shown in FIG. 2 is used, and the conical prism 5 is brought close to or brought into contact with the diffractive optical element 4 by the third drive system 23. Circular illumination can also be performed by. As shown in FIG. 1, the light emitted from the diffractive optical element 4 has a completely annular cross section at a predetermined distance, but if it enters the conical prism 5 before the light flux becomes annular, it does not look like an import belt. Instead, it can be circular illumination. Therefore, by bringing the conical prism 5 close to or in contact with the diffractive optical element 4, circular illumination can be performed without using the microlens array 41 for circular illumination or the diffractive optical element 42. Furthermore, although the fly-eye lens 9 is used in the first and second embodiments, a condenser lens and a rod integrator may be used instead of the fly-eye lens 9.

Furthermore, in the above-described second embodiment, the annular light source or the quadrupole light source is formed as an example in the modified illumination, but it is composed of two surface light sources eccentric with respect to the optical axis. It is also possible to form a so-called multi-pole or multi-pole secondary light source such as a pole-shaped secondary light source or an 8-pole-shaped secondary light source composed of eight surface light sources eccentric to the optical axis. .

In the second embodiment described above, the condenser optical system 10 collects the light from the secondary light source to illuminate the mask M in a superimposed manner, but the condenser optical system 10 and the mask M are combined. In between, the illumination field stop (mask blind) and the image of this illumination field stop are masked by M
You may arrange | position the relay optical system formed above. In this case, the condenser optical system 10 condenses the light from the secondary light source and illuminates the illumination field stop in a superimposed manner, and the relay optical system controls the aperture (light transmitting part) of the illumination field stop. An image will be formed on the mask M.

Further, in the above-described second embodiment, the present invention has been described by taking the exposure apparatus provided with the illumination optical apparatus as an example, but it is a general illumination optical apparatus for uniformly illuminating the illuminated surface other than the mask. It is obvious that the present invention can be applied.

By exposing the photosensitive substrate with the pattern of the mask by using the exposure apparatus of the second embodiment configured as described above (exposure step), microdevices (semiconductor element, image pickup element, liquid crystal display element, Thin film magnetic heads, etc.) can be manufactured. Hereinafter, an example of a method for obtaining a semiconductor device as a micro device by forming a predetermined circuit pattern on a wafer or the like as a photosensitive substrate using the exposure apparatus of the second embodiment shown in FIG. 7 will be described with reference to FIG. This will be described with reference to the flowchart in FIG.

First, in step 301 of FIG. 9, 1
A metal film is deposited on a lot of wafers. In the next step 302, photoresist is applied on the metal film on the wafer of the 1 lot. Then step 303
In, using the exposure apparatus of the second embodiment, the image of the pattern on the mask (reticle) is sequentially transferred to each shot area on the wafer of the one lot through the projection optical system. Then, in step 304, the photoresist on the one lot of wafers is developed, and in step 305, the resist pattern is used as a mask on the one lot of wafers to form a pattern on the mask. Corresponding circuit patterns are formed in each shot area on each wafer. After that, a device such as a semiconductor element is manufactured by forming a circuit pattern on an upper layer. According to the above-described semiconductor device manufacturing method, it is possible to obtain a semiconductor device having an extremely fine circuit pattern with high throughput.

Further, in the exposure apparatus of the second embodiment, a liquid crystal display element as a microdevice can be obtained by forming a predetermined pattern (circuit pattern, electrode pattern, etc.) on a plate (glass substrate). .
Hereinafter, an example of the method at this time will be described with reference to the flowchart in FIG. 10. In FIG. 10, in a pattern forming step 401, a so-called photolithography step is performed in which the reticle pattern is transferred and exposed onto a photosensitive substrate (such as a glass substrate coated with a resist) using the exposure apparatus of the second embodiment. . By this photolithography process, a predetermined pattern including a large number of electrodes and the like is formed on the photosensitive substrate. Then, the exposed substrate is subjected to a development process,
A predetermined pattern is formed on the substrate through each step such as the etching step and the reticle peeling step, and the process proceeds to the next color filter forming step 402.

Next, in the color filter forming step 402, 3 corresponding to R (Red), G (Green) and B (Blue)
Many sets of one dot are arranged in a matrix,
Alternatively, a color filter in which a plurality of R, G, and B stripe filter sets are arranged in the horizontal scanning line direction is formed. Then, after the color filter forming step 402, the cell assembling step 403 is executed. In the cell assembly step 403, a liquid crystal panel (liquid crystal cell) is assembled using the substrate having the predetermined pattern obtained in the pattern formation step 401, the color filter obtained in the color filter formation step 402, and the like. In the cell assembling step 403, for example, a liquid crystal is injected between the substrate having the predetermined pattern obtained in the pattern forming step 401 and the color filter obtained in the color filter forming step 402 to form a liquid crystal panel (liquid crystal cell). ) Is manufactured.

After that, in a module assembling step 404, each component such as an electric circuit and a backlight for performing display operation of the assembled liquid crystal panel (liquid crystal cell) is attached to complete a liquid crystal display element. According to the method of manufacturing a liquid crystal display element described above, a liquid crystal display element having an extremely fine circuit pattern can be obtained with high throughput.

Although the ArF excimer laser light source is used as the light source in each of the above-described embodiments, the light source is not limited to this, and may be, for example, an F ₂ laser light source (wavelength: 157 nm) or a KrF excimer laser light source (wavelength). :
248 nm) or the like can also be used.

[0056]

As described above, according to the present invention, for example, by combining the diffractive optical element as the first light beam converting element and the conical prism as the second light beam converting element,
A parallel light flux having a predetermined cross-sectional shape required for modified illumination is formed. Therefore, in the exposure apparatus provided with the illumination optical device of the present invention, even if the exposure light of the short wavelength is used to improve the resolution, the light quantity loss is well suppressed based on the simple configuration with a small number of optical members. Deformed illumination can be performed. Further, based on the modified illumination in which the light amount loss is well suppressed, it is possible to manufacture a good microdevice with high throughput and high resolution.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a configuration of an illumination optical device according to a first embodiment of the invention.

FIG. 2 is a diagram illustrating an operation of the diffractive optical element for a ring zone in the first embodiment.

FIG. 3 is a diagram illustrating a ring-shaped illumination region formed on the illuminated surface and changes in the ring-shaped illumination region due to the actions of the afocal zoom lens and the conical prism in the first embodiment.

FIG. 4 is a diagram for explaining the action of a conical prism.

FIG. 5 is a diagram for explaining the operation of the diffractive optical element for four poles in the first embodiment.

FIG. 6 is a diagram illustrating a quadrupole illumination region formed on the illuminated surface and changes in the quadrupole illumination region due to the actions of the afocal zoom lens and the conical prism in the first embodiment.

FIG. 7 is a diagram schematically showing a configuration of an exposure apparatus including an illumination optical device according to a second embodiment of the present invention.

FIG. 8 is a diagram illustrating the operation of a diffractive optical element for circular illumination that can be used in the second embodiment.

FIG. 9 is a flowchart of a method for obtaining a semiconductor device as a microdevice using the exposure apparatus of the second embodiment.

FIG. 10 is a flowchart of a method for obtaining a liquid crystal display element as a microdevice by using the exposure apparatus of the second embodiment.

[Explanation of symbols]

1 light source 3 Afocal zoom lens 4,40 Diffractive optical element 5 conical prism 7,41 Micro lens array 8 Imaging lens system 9 fly eye lens 10 Condenser optical system 21-23 Drive system M mask PL projection optical system W wafer

─────────────────────────────────────────────────── ─── Continued Front Page (51) Int.Cl. ⁷ Identification Code FI Theme Coat (Reference) H01L 21/027 H01L 21/30 515D

Claims (8)

[Claims] 1. An illumination optical device for illuminating a surface to be illuminated, comprising: a light source means for supplying a substantially parallel light flux; and a substantially parallel light flux from the light source means for converting into a divergent light flux having a predetermined cross-sectional shape. A first light flux conversion element and a second light flux conversion element for converting the divergent light flux from the first light flux conversion element into a substantially parallel light flux, wherein the first light flux conversion element is a diffractive optical element or a microlens array. An illuminating optical device comprising: 2. A driving means for moving the second light flux conversion element along the optical axis in order to change the size of the cross-sectional shape of the substantially parallel light flux formed through the second light flux conversion element. The illumination optical apparatus according to claim 1, further comprising: 3. The illumination optical device according to claim 1, wherein the second light flux conversion element has a conical prism having a flat surface on one side and a conical surface on the other side. . 4. A variable power optical system further arranged in the optical path between the light source means and the first light flux conversion element or in the optical path between the second light flux conversion element and the illuminated surface. The illumination optical device according to any one of claims 1 to 3, wherein: 5. An optical integrator for forming a large number of light sources on the basis of the light beams passed through the second light beam conversion element, and a light guiding optical system for guiding the light beams from the plurality of light sources to the irradiation surface. The illumination optical device according to any one of claims 1 to 4, further comprising: 6. A variable power optical system arranged in an optical path between the second light flux conversion element and the illuminated surface is arranged in an optical path between the second light flux conversion element and the optical integrator. The illumination optical device according to claim 5, wherein the illumination optical device is provided. 7. An illumination optical device according to claim 1, and a projection optical system for projecting and exposing a pattern of a mask set on the surface to be illuminated onto a photosensitive substrate. An exposure apparatus characterized by being provided. 8. An exposure step of exposing the pattern of the mask onto the photosensitive substrate by the exposure apparatus according to claim 7, and a development step of developing the photosensitive substrate exposed by the exposure step. A method for manufacturing a microdevice, which is characterized by the above.