KR20020005975A - An illumination optical apparatus - Google Patents

Abstract

PURPOSE: To improve the resolution of a projecting optical system to a prescribed pattern shape, while satisfactorily suppressing light quantity loss and securing a prescribed focus depth. CONSTITUTION: This device is provided with angle luminous flux forming means (4 and 5), for converting luminous fluxes from a light source means (1) into the luminous fluxes provided with various angle components to a reference optical axis (AX) and making them be incident on a first prescribed surface, irradiation field formation means (6 and 7) for forming tow irradiation fields which is eccentric almost symmetrical with respect to the reference optical axis on a second prescribed surface, based on the incident luminous fluxes provided with the various angle components, an optical integrator (8) for forming a bipolar secondary light source provided with the almost same light intensity distribution, based on the luminous fluxes from the formed two irradiation fields and a light guide optical system (10), for guiding the luminous fluxes from the optical integrator to a surface (M) to be irradiated.

Description

Manufacture method of illumination optical apparatus, exposure apparatus, and microdevices {AN ILLUMINATION OPTICAL APPARATUS}

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to an illumination optical apparatus and an exposure apparatus provided with the illumination optical apparatus, in particular illumination optics suitable for an exposure apparatus for manufacturing a device such as a semiconductor element, an imaging element, a liquid crystal display element or a thin film magnetic head by a lithography process. Relates to a device.

In a typical exposure apparatus of this kind, the light beam emitted from the light source enters the fly's eye lens, and forms a secondary light source consisting of a plurality of light source images on the rear focal plane. The light beam from the secondary light source enters the condenser lens after being limited via an aperture stop disposed near the rear focal plane of the fly's eye lens. The aperture stop restricts the shape or size of the secondary light source to the desired shape or size in accordance with a desired illumination condition (exposure condition).

The luminous flux collected by the condenser lens illuminates a mask in which a predetermined pattern is formed. Light transmitted through the pattern of the mask is imaged on the wafer through the projection optical system. In this way, the mask pattern is subjected to projection exposure (transfer) on the wafer. In addition, the pattern formed on the mask is highly integrated, and in order to accurately transfer the fine pattern onto the wafer, it is essential to obtain a uniform illuminance distribution on the wafer.

In recent years, the size of the secondary light source formed by the fly's eye lens is changed by changing the size of the opening (light transmitting portion) of the aperture stop disposed on the exit side of the fly's eye lens, thereby coherence of illumination. The technique of changing (sigma) ((sigma) value = opening aperture diameter / projection diameter of a projection optical system, or (sigma) value = exit side numerical aperture of a projection optical system / incidence side numerical aperture of a projection optical system) attracts attention. Further, by setting the shape of the opening of the aperture stop on the exit side of the fly's eye lens to a ring-shaped or four-hole shape (that is, a four-pole shape), the secondary light source formed by the fly's eye lens The technique which restrict | limits a shape to ring shape and quadrupole shape, and improves the depth of focus and resolution of a projection optical system is attracting attention.

As described above, in the prior art, a relatively large two formed by a fly's eye lens is used to restrict the shape of the secondary light source to a ring-shaped or quadrupole shape so as to perform deformation illumination (ring-ring illumination or quadrupole illumination). The luminous flux from the difference light source is limited by an aperture stop having an annular or quadruple opening. In other words, in the annular illumination and the quadrupole illumination in the prior art, a substantial portion of the luminous flux from the secondary light source is shielded by the aperture stop and does not contribute to illumination (exposure). As a result, there is a problem that the illuminance on the mask and the wafer decreases due to the loss of light amount in the aperture stop, and the throughput as the exposure apparatus also decreases. Moreover, since various pattern shapes exist also about the mask pattern to be transferred, the illumination technique which improves the resolution of the projection optical system with respect to a specific pattern shape is desired, without reducing the depth of focus.

An object of the present invention is to perform modified illumination for improving the resolution of a projection optical system with respect to a specific pattern shape while satisfactorily suppressing light loss and securing a predetermined depth of focus.

1 is a view schematically showing the configuration of an exposure apparatus with an illumination optical device according to Embodiment 1 of the present invention;

FIG. 2 schematically shows the configuration of the micro fly eye 4 of FIG. 1;

3 is a view for explaining the operation of the diffractive optical element 6 for dipole illumination,

FIG. 4 is a diagram illustrating a dipole-shaped illumination region formed on the incident surface of the fly's eye lens 8 while explaining the operation of the diffractive optical element 6 for dipole illumination.

5 is a diagram schematically showing the configuration of a turret in which a plurality of aperture stops are arranged in a circumferential shape;

FIG. 6 is a diagram schematically showing the configuration from the micro fly's eye 4 to the entrance face of the fly's eye lens 8, wherein the magnification of the afocal zoom lens 5 and the focus of the zoom lens 7 are shown. A diagram illustrating the relationship between the distance and the size and shape of the dipole-shaped illumination region formed on the incident surface of the fly's eye lens 8,

7 is a diagram schematically showing the configuration of an exposure apparatus with an illumination optical device according to Embodiment 2 of the present invention;

8 is a diagram schematically showing a main part configuration of a modification of the first embodiment and the second embodiment;

9 is a flowchart of a method for obtaining a semiconductor device as a micro device.

Explanation of symbols for the main parts of the drawings

1: light source 2: beam expander

3: bending mirror 4: micro fly eye

5: apocal zoom lens 6: diffractive optical element

7: zoom lens 8: fly-eye lens

9 aperture aperture 10 condenser optical system

20: input means 21: control system

22: first drive system 23: second drive system

24: third drive system 25: fourth drive system

26: fifth drive system PL: projection optical system

In order to achieve the above object, the illumination optical device according to any aspect of the present invention is used in a projection exposure apparatus that transfers an image of a pattern on a mask onto a substrate via a projection optical system, and illuminates the mask. An illumination optical device for performing the above, comprising: a light source means for supplying a luminous flux of an exposure wavelength, and an eccentricity almost symmetrically with respect to a reference optical axis in an illumination pupil which is conjugate with the pupil of the projection optical system based on the luminous flux from the light source means. The secondary light source forming means for forming two surface light sources, the distance from the reference optical axis of the two surface light sources, the size of each of the two surface light sources, and the two surface light sources; It has a variable speed optical system for continuously changing the azimuth angle which is the angle anticipated from an optical axis.

In a typical embodiment of the present invention, an angular light beam forming means and an illumination region forming means are arranged in the optical path between the light source means and the optical integrator. Specifically, the angular luminous flux forming means includes a diverging luminous flux forming element such as a micro fly's eye for converting a substantially parallel luminous flux from the light source means into a luminous flux diverging at various angles with respect to the reference optical axis, and a divergence formed through the micro fly's eye. It consists of an optical system, such as an apocal zoom lens, which condenses a light beam and guides it to the diffraction surface of the diffraction optical element as a light beam conversion element mentioned later. Therefore, the substantially parallel luminous flux from the light source means passes through the micro fly's eye and the apocal zoom lens and becomes a luminous flux having various angular components with respect to the reference optical axis and enters into the diffractive optical element.

On the other hand, the illumination region forming means includes a plurality of light beam conversion elements such as diffractive optical elements for converting the incident light beams into plural (2) light beams eccentric with respect to the reference optical axis, and a plurality (two) formed through the diffractive optical elements. Based on the luminous flux, an optical system such as a zoom lens for forming a plurality of illumination regions eccentric with respect to a reference optical axis is formed on the incident surface of an optical integrator such as a fly's eye lens. Here, the plurality (two) illumination regions eccentric with respect to the reference optical axis are, for example, two illumination regions symmetrically symmetrically with respect to the reference optical axis, that is, a dipole-shaped illumination region.

Thus, by the action of the angular light beam forming means composed of the micro fly's eye and the apocal zoom lens and the illumination region forming means composed of the diffractive optical element and the zoom lens, the incident surface of the fly's eye lens has a two-pole illumination region. Is formed. As a result, similarly, a bipolar secondary light source is formed on the rear focal plane of the fly's eye lens. The luminous flux from the secondary light source formed by the fly's eye lens thus illuminates the mask to be irradiated after being limited by an aperture stop having an opening corresponding to the size and shape of the secondary light source.

As described above, according to the present invention, a bipolar secondary light source can be formed on the basis of the luminous flux from the light source means, with almost no light loss. As a result, deformed illumination can be performed to improve the resolution of the projection optical system for a specific pattern shape while satisfactorily suppressing light loss in the aperture stop restricting the luminous flux from the secondary light source and ensuring a predetermined depth of focus. Can be. That is, in dipole illumination based on a bipolar secondary light source, the resolution of the projection optical system can be improved mainly with respect to the pattern shape along one direction. It goes without saying that normal circular illumination can be performed while suppressing light loss well by evacuating the micro fly's eye from the illumination light path.

In addition, in the embodiment of the present invention, by changing the magnification of the apocal zoom lens, the outer diameter and the ring band ratio of the secondary light source can be changed together. In addition, by changing the focal length of the zoom lens, the outer diameter can be changed without changing the annular ratio of the secondary light source. As a result, by appropriately changing the magnification of the apocal zoom lens and the focal length of the zoom lens, the annular obesity can be changed without changing the outer diameter of the secondary light source.

As described above, in the illumination optical apparatus according to the embodiment of the present invention, modified illumination such as dipole illumination and ordinary circular illumination can be performed while satisfactorily suppressing light loss in the aperture stop restricting the secondary light source. have. In addition, by a simple operation of changing the magnification of the apocal zoom lens or changing the focal length of the zoom lens, the parameters of the modified illumination (the size and shape of the limited secondary light source) can be suppressed with good suppression of the amount of light at the aperture stop. ) Can be changed.

Therefore, in the exposure apparatus incorporating the illumination optical apparatus according to the embodiment of the present invention, the type and parameters of the modified illumination can be appropriately changed to obtain the resolution and depth of focus of the projection optical system suitable for the fine pattern to be subjected to exposure projection. As a result, good projection exposure with high throughput can be performed based on high exposure illuminance and good exposure conditions. Further, in the exposure method of exposing a pattern of a mask disposed on an irradiated surface on a photosensitive substrate using the illumination optical device according to the embodiment of the present invention, since the projection exposure can be performed based on favorable exposure conditions, The device can be manufactured.

The above and other objects, features, aspects, advantages, and the like of the present invention will become more apparent from the following detailed embodiments described with reference to the accompanying drawings.

(Example 1)

Embodiments of the present invention will be described with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows roughly the structure of the exposure apparatus provided with the illumination optical apparatus which concerns on Embodiment 1 of this invention. In Fig. 1, the Z axis is set along the normal direction of the wafer W as the photosensitive substrate, the Y axis is set in the direction parallel to the ground of Fig. 1 in the wafer plane, and the X axis is set in the direction perpendicular to the ground of Fig. 1 in the wafer plane. have. In addition, in FIG. 1, the illumination optical apparatus is set so that dipole illumination may be performed.

The exposure apparatus of FIG. 1 is provided with the excimer laser light source which supplies light of 248 nm or 193 nm wavelength, for example as the light source 1 for supplying exposure light (lighting). The substantially parallel luminous flux emitted from the light source 1 along the Z direction has a rectangular cross section extending elongated along the X direction and consists of a pair of cylindrical lenses 2a and 2b. It is incident on the beam expander 2. Each cylindrical lens 2a and 2b has a negative refractive power and a positive refractive power in the paper surface (in the YZ plane) of FIG. 1, respectively, and includes an optical axis AX and is orthogonal to the paper surface. It functions as a parallel plane plate in surface (in XZ plane). Therefore, the light beam incident on the beam expander 2 is enlarged in the sheet of FIG. 1 and shaped into a light beam having a predetermined rectangular cross section.

The nearly parallel luminous flux passing through the beam expander 2 as the shaping optical system is deflected in the Y direction by the bent mirror 3 and then enters the micro fly eye 4. The micro fly's eye 4 is an optical element composed of a microlens 4a having a large number of regular hexagonal positive refractive powers arranged densely and vertically and horizontally as shown in FIGS. 1 and 2. Generally, a micro fly's eye is comprised by carrying out an etching process to a parallel flat glass plate, for example, and forming a microlens group.

Here, each micro lens constituting the micro fly's eye is finer than each lens element constituting the fly's eye lens. In addition, unlike a fly's eye lens composed of lens elements that are engraved with each other, the micro fly's eyes are formed integrally without a large number of micro lenses being engraved with each other. However, the micro fly's eye is the same as the fly's eye lens in that the lens elements having the refractive power are arranged longitudinally and horizontally. In addition, in FIG. 1 and FIG. 2, the number of the microlenses 4a which comprise the micro fly's eye 4 is set very much smaller than actually for clarity of drawing.

Therefore, the light beam incident on the micro fly's eye 4 is divided two-dimensionally by a plurality of micro lenses, and one light source (condensing point) is formed on the rear focal plane of each micro lens. The light beams from the plurality of light sources formed on the rear focal plane of the micro fly's eye 4 become divergent light beams each having a regular hexagonal cross section, and enter the apocal zoom lens 5. As described above, the micro fly's eye 4 is an optical element array having a plurality of unit optical elements (microlenses) arranged in a two-dimensional shape, and the light beam 1 has a substantially parallel luminous flux at various angles with respect to the optical axis AX. A divergent light beam forming element for converting into a luminous flux emitted by? Is constructed.

Moreover, the micro fly eye 4 is comprised freely in an insertion / separation with respect to an illumination optical path. The apocal zoom lens 5 is configured to continuously change the magnification in a predetermined range while maintaining the apocal system (focal optical system). Here, the evacuation from the illumination light path of the micro fly's eye 4 is performed by the first drive system 22 operating based on the command from the control system 21. In addition, the change of the magnification of the apocal zoom lens 5 is performed by the second drive system 23 operating based on the command from the control system 21.

The light beam passing through the apocal zoom lens 5 is incident on the diffractive optical element (DOE) 6 for dipole illumination. At this time, the divergent light flux from each light source formed on the rear focal plane of the micro fly's eye 4 converges on the diffractive surface of the diffractive optical element 6 while maintaining the regular hexagonal cross section. That is, the apocal zoom lens 5 optically conjugates the rear focal plane of the micro fly's eye 4 and the diffraction plane of the diffractive optical element 6. The numerical aperture of the luminous flux condensed at a point on the diffraction surface of the diffractive optical element 6 is changed depending on the magnification of the apocal zoom lens 5.

Generally, a diffractive optical element is comprised by forming the level | step difference which has a pitch about the wavelength of exposure light (illumination light) on a glass substrate, and has the effect | action which diffracts an incident beam at a desired angle. Specifically, the dipole optical diffraction optical element 6 converts the thin light flux vertically incident in parallel with the optical axis AX into two light fluxes traveling according to a predetermined exit angle as shown in Fig. 3A. do. In other words, the thin light beams vertically incident along the optical axis AX are diffracted along two directions specified at an equiangular angle with respect to the optical axis AX, resulting in two thin light beams. More specifically, the thin light flux perpendicularly incident on the diffractive optical element 6 is converted into two light fluxes, and the passing center point of the two light fluxes passing through the rear plane parallel to the diffractive optical element 6 is determined. The center of the connecting line segment is present on the incident axis to the diffractive optical element 6. In this manner, the diffractive optical element 6 constitutes a light flux conversion element for converting the incident light flux into two light fluxes.

Therefore, as shown in Fig. 3B, when a thick parallel light beam is incident perpendicularly to the diffractive optical element 6, the focal position of the lens 31 arranged behind the diffractive optical element 6 is also 2 Dot shapes (point shape light source images) 32 are formed. In other words, the diffractive optical element 6 forms a two-point light intensity distribution in the far field (or Fraunhofer diffraction region). In addition, the lens 31 forms a two-point light intensity distribution formed in the far field (or Fraunhofer diffraction region) on the rear focal plane.

Here, as shown in FIG. 3C, when the thick parallel light beam incident on the diffractive optical element 6 is inclined with respect to the optical axis AX, two images formed at the focal position of the lens 31 move. That is, when the coarse luminous flux incident on the diffractive optical element 6 is inclined along a predetermined plane, the two point images 33 formed at the focal position of the lens 31 do not change their size, and the center thereof is not changed. Along the predetermined plane, the light flux moves in a direction opposite to the tilting direction.

As described above, the divergent light flux from each light source formed on the rear focal plane of the micro fly's eye 4 is converged on the diffractive surface of the diffractive optical element 6 while maintaining the regular hexagonal cross section. In other words, although the light beam which has various angular components injects into the diffraction optical element 6, the incidence angle is defined by the light beam range of a regular hexagonal cone shape. Therefore, as shown in Fig. 4A, the angle of the light beam range of the regular hexagonal shape is centered around the two-point image 40 formed by the light beam incident perpendicularly to the diffractive optical element 6. The light beams incident at the maximum angle corresponding to the ridge line form two-point images 41 to 46 at the focal position of the lens 31. In fact, since an infinite number of luminous fluxes having a large number of angular components defined by the luminous flux range of the regular hexagonal shape are incident on the diffractive optical element 6, an infinite two-point shape is formed at the focal position of the lens 31. The images of are superimposed, and as a whole, a dipole-shaped illumination region as shown in Fig. 4B is formed.

The diffractive optical element 6 is configured to be freely inserted / separated from the illumination optical path, and the diffractive optical element 60 for eight-pole illumination, the diffractive optical element 61 for modified four-pole illumination, or the diffraction optical element for ordinary circular illumination. It is comprised so that switching with 62 is possible. The structures and operations of the eight-pole diffraction optical element 60, the modified four-pole illumination diffraction optical element 61, and the normal circular illumination diffraction optical element 62 will be described later. Here, the switching between the diffraction optical element 6 for dipole illumination, the diffraction optical element 60 for eight pole illumination, the diffraction optical element 61 for modified quadrupole illumination, and the diffraction optical element 62 for normal circular illumination is controlled by the control system 21. Is performed by the third drive system 24 operating based on the command from

Referring again to FIG. 1, the light beam passing through the diffractive optical element 6 enters the zoom lens 7. Here, the zoom lens 7 has the same effect as the lens 31 shown in FIG. Further, near the rear focal plane of the zoom lens 7, the incident surface of the fly's eye lens 8 as the optical integrator is positioned. Therefore, the light beam passing through the diffractive optical element 6 is directed to the rear focal plane of the zoom lens 7 and further to the optical axis AX as shown in Fig. 4B on the plane of incidence of the fly's eye lens 8. Two illumination regions symmetrically eccentric with respect to, i.e., dipole-shaped illumination regions are formed. The size of the dipole-shaped illumination region (the diameter of the circle circumscribed to the dipole-shaped illumination region) is changed depending on the focal length of the zoom lens 7. In this manner, the zoom lens 7 has a relationship of substantially Fourier transforming the incidence surfaces of the diffractive optical element 6 and the fly's eye lens 8. In addition, the change of the focal length of the zoom lens 7 is performed by the fourth drive system 25 operating based on the command from the control system 21.

The fly's eye lens 8 is constituted by arranging a plurality of lens elements having positive refractive power in a dense and longitudinal direction. Each lens element constituting the fly's eye lens 8 has a rectangular cross section similar to the shape of the illumination region to be formed on the mask (the shape of the exposure region to be formed on the wafer). The incidence surface of each lens element constituting the fly's eye lens 8 is formed in a spherical shape facing the convex surface on the incidence side, and the incidence side surface is formed in a spherical shape facing the convex surface on the injection side. have.

Accordingly, the light beams incident on the fly's eye lens 8 are divided two-dimensionally by a plurality of lens elements, and light sources are formed on the rear focal planes of the respective lens elements on which the light beams are incident. In this way, a bipolar surface light source (hereinafter referred to as a “secondary light source”) having a light intensity distribution substantially equal to the illumination region formed by the light beam incident on the fly's eye lens 8 on the rear focal plane of the fly's eye lens 8. "Is formed. The light beam from the bipolar secondary light source formed on the rear focal plane of the fly's eye lens 8 enters the aperture stop 9 arranged in the vicinity thereof. This aperture stop 9 is supported on a turret (rotating plate: not shown in Fig. 1) that can rotate around a predetermined axis parallel to the optical axis AX.

5 is a diagram schematically showing the configuration of a turret in which a plurality of aperture stops are arranged in a circumferential shape. As shown in FIG. 5, the turret substrate 400 is provided with eight aperture diaphragms having light transmissive regions indicated by diagonal lines in the drawing along the circumferential direction. The turret substrate 400 is configured to be rotatable about an axis parallel to the optical axis AX through the center point O thereof. Therefore, by rotating the turret substrate 400, one aperture stop selected from the eight aperture stops can be positioned in the illumination light path. The turret substrate 400 is rotated by a fifth drive system 26 that operates based on instructions from the control system 21.

Three turret aperture stops 401, 403, and 405 having different ring width ratios are formed in the turret substrate 400. Here, the bipolar aperture stop 401 has two circular transmissive regions arranged symmetrically with respect to the center thereof in a annular region having an annular band ratio of r11 / r21. The bipolar aperture stop 403 has two circular transmissive regions arranged symmetrically with respect to the center thereof in a annular region having an annular band ratio of r12 / r22. The bipolar aperture stop 405 has two circular transmissive regions arranged symmetrically about its center in a annular region having an annular band ratio of r13 / r21.

The turret substrate 400 is formed with three eight-pole aperture stops 402, 404, and 406 having different annular band ratios.

In addition, two circular aperture stops 407 and 408 having different sizes (diameters) are formed in the turret substrate 400. Here, the circular aperture diaphragm 407 has a circular transmissive region of size 2r22, and the circular aperture diaphragm 408 has a circular transmissive region of size 2r21.

In addition, although separately shown by the limitation of the paper surface, three modified four-pole aperture stops 409 to 411 having different annular band ratios are formed in the turret substrate 400.

Therefore, by selecting one of the two annular aperture diaphragms 401, 403, and 405 and positioning them in the illumination light path, the two-pole-shaped beam having three different annular band ratios can be accurately determined. By restricting (regulation), three kinds of dipole illuminations having different annular band ratios can be performed.

Further, by selecting one circular aperture diaphragm from the two circular aperture diaphragms 407 and 408 and positioning it in the illumination optical path, two types of normal circular illumination having different sigma values can be performed.

In FIG. 1, since the secondary polarized light source is formed on the rear focal plane of the fly's eye lens 8, one dipole aperture stop selected from the three dipole aperture stops 401, 403, and 405 is opened. It is used as the aperture 9. However, the structure of the turret shown in FIG. 5 is illustrative, The kind and number of aperture stops arrange | positioned are not limited to this. Furthermore, the aperture stop may be fixedly mounted in the illumination optical path, without being limited to the turret type aperture stop, which can appropriately change the size and shape of the light transmission region. Instead of the two circular aperture diaphragms 407 and 408, an iris diaphragm capable of continuously changing the circular aperture diameter may be provided.

The light from the secondary light source passing through the aperture diaphragm 9 having a bipolar opening (light transmitting part) receives the light condensing action of the condenser optical system 10 as the light guide optical system, and then overlaps the mask M on which a predetermined pattern is formed. Uniform illumination. The light beam which permeate | transmitted the pattern of the mask M forms the image of a mask pattern on the wafer W which is a photosensitive board | substrate through the projection optical system PL. In this way, the collective exposure or scan exposure is performed while driving the wafer W two-dimensionally in a plane (XY plane) orthogonal to the optical axis AX of the projection optical system PL, so that the pattern of the mask M is applied to each exposure area of the wafer W. This is gradually exposed.

Moreover, in package exposure, a mask pattern is exposed collectively with respect to each exposure area | region of a wafer according to what is called a step and repeat system. In this case, the shape of the illumination region on the mask M is a rectangular shape close to the square, and the cross-sectional shape of each lens element of the fly's eye lens 8 also becomes a rectangular shape close to the square. According to the end-scan method, a mask pattern is scanned and exposed to each exposure area of the wafer while moving the mask and the wafer relative to the projection optical system. In this case, the shape of the illumination region on the mask M has a ratio of short side to long side, for example, 1: 3 rectangular shape, and the cross-sectional shape of each lens element of the fly's eye lens 8 also becomes a rectangular shape similar to this. .

FIG. 6 is a view schematically showing the configuration from the micro fly's eye 4 to the entrance face of the fly's eye lens 8, wherein the magnification of the apocal zoom lens 5 and the focal length of the zoom lens 7 are shown; It is a figure explaining the relationship between the magnitude | size and shape of the dipole-shaped illumination area | region formed in the incident surface of the fly-eye lens 8. As shown in FIG. In Fig. 6, the light ray 70 incident along the optical axis AX to the center of the microlenses disposed on the optical axis AX of the micro fly's eye 4 is emitted along the optical axis AX. The micro fly's eye 4 is composed of a microlens having a size (a dimension corresponding to the diameter of a circle circumscribed in a regular hexagon) and a focal length of f1. The light ray 70 passes through the apocal zoom lens 5 and then enters the diffractive optical element 6 along the optical axis AX.

The diffractive optical element 6 forms a light ray 70a emitted at an angle θ with respect to the optical axis AX based on the light ray 70 incident perpendicularly along the optical axis AX. The light beam 70a emitted from the diffractive optical element 6 at an angle θ reaches the incident surface of the fly's eye lens 8 via the zoom lens 7 having a focal length f2. At this time, the position of the light ray 70a on the incident surface of the fly's eye lens 8 has a height of y from the optical axis AX. On the other hand, the light ray 71 incident in parallel with the optical axis AX to the uppermost edge of the microlens disposed on the optical axis AX of the micro fly's eye 4 is emitted at an angle t with respect to the optical axis AX. This light ray 71 passes through the apocal zoom lens 5 at magnification m, and then enters the diffractive optical element 6 at an angle t 'with respect to the optical axis AX.

The light rays 71 incident on the diffractive optical element 6 at an angle t 'with respect to the optical axis AX are converted into various light rays including the light rays 71a emitted at an angle θ + t' with respect to the optical axis AX. The light beam 71a emitted from the diffractive optical element 6 at an angle θ + t 'with respect to the optical axis AX passes through the zoom lens 7 from the optical axis AX at the incident surface of the fly's eye lens 8 ( y + b). Further, the light ray 72 incident in parallel with the optical axis AX at the lowermost edge of the microlens disposed on the optical axis AX of the microfly eye 4 is emitted at an angle t with respect to the optical axis AX. The light ray 72 passes through the apocal zoom lens 5 and then enters the diffractive optical element 6 at an angle t 'with respect to the optical axis AX.

The light ray 72 incident on the diffractive optical element 6 at an angle t 'with respect to the optical axis AX is converted into various light rays including a light ray (not shown) emitted at an angle θ-t' with respect to the optical axis AX. do. The light emitted from the diffractive optical element 6 at an angle θ-t 'with respect to the optical axis AX passes through the zoom lens 7 and has a height of (yb) from the optical axis AX at the incident surface of the fly's eye lens 8. To reach.

In this way, the range in which the divergent light flux from each light source formed near the rear focal plane of the micro fly's eye 4 reaches the incidence plane of the fly's eye lens 8 is a bipolar shape shown in Fig. 4B. In the illumination region of, the range has a width 2b around the height of y from the optical axis AX. That is, as shown in FIG. 6 (b), the dipole-shaped illumination region formed on the incident surface of the fly's eye lens 8, and further, the dipole formed on the rear focal plane of the fly's eye lens 8 The shaped secondary light source has a center height y from the optical axis AX and a width 2b.

Here, the exit angle t from the micro fly's eye 4 and the incident angle t 'to the diffractive optical element 6 are represented by the following equations (1) and (2).

In addition, the center height y, the highest height (y + b), and the minimum height (y-b) of the bipolar secondary light source are represented by the following equations (3) to (5).

Therefore, the annular band ratio A defined by the ratio of the inner diameter phi i and the outer diameter phi o of the bipolar secondary light source is expressed by the following expression (6). Here, as shown in Fig. 6B, the inner diameter phi i is the diameter of the circle inscribed in a pair of circles (corresponding to the opening of the opening diaphragm 9) inscribed in a regular hexagonal surface light source. In addition, the outer diameter phi o is the diameter of the circle circumscribed to the pair of circles.

In addition, the outer diameter phi o of the bipolar secondary light source is represented by the following expression (7).

Thus, referring to Equations 2 to 6, if the magnification m of the apocal zoom lens 5 is changed, only the width 2b is changed without changing the center height y of the bipolar secondary light source. Able to know. That is, by changing the magnification m of the apocal zoom lens 5, both the magnitude | size (outer diameter (phi) o) of the bipolar secondary light source and its shape (ring-ring ratio A) can be changed.

In addition, referring to Equations 3 to 7, if the focal length f2 of the zoom lens 7 is changed, the center height y and the width 2b are determined without changing the ring-band ratio A of the bipolar secondary light source. It can be seen that all change. That is, by changing the focal length f2 of the zoom lens 7, the outer diameter? O can be changed without changing the annular band ratio A of the bipolar secondary light source. From the above, by appropriately changing the magnification m of the apocal zoom lens 5 and the focal length f2 of the zoom lens 7, the ring ratio A is not changed without changing the outer diameter phi o of the secondary light source. Only you can change it.

In addition, as shown in Fig. 6B, although two regular hexagon-shaped surface light sources symmetrically eccentric with respect to the optical axis AX are formed as secondary light sources, the distance y from the optical axis AX of each surface light source, each The size (width) 2b of the surface light source and the angle at which each surface light source is estimated from the optical axis AX, that is, the azimuth angle φ, are continuously changed according to the magnification m of the apocal zoom lens 5 and the focal length f2 of the zoom lens 7. Will change. As described above, when the diffractive optical element 6 for dipole illumination is used, a bipolar secondary light source can be formed on the basis of the luminous flux from the light source 1 with almost no light loss, and as a result, Two-pole illumination can be performed while suppressing the loss of light quantity in the aperture stop 9 which limits the luminous flux from a light source.

Next, the normal circular illumination obtained by evacuating the micro fly's eye 4 from the illumination optical path and setting the diffractive optical element 62 for circular illumination in the illumination optical path instead of the diffractive optical element 6, 60 or 61 will be described. do. In this case, a light beam having a rectangular cross section enters the apocal zoom lens 5 along the optical axis AX. The light beam incident on the apocal zoom lens 5 is enlarged or reduced in accordance with its magnification, and is emitted from the apocal zoom lens 5 along the optical axis AX as it has a rectangular cross section, and is diffracted optical element 62. ).

The diffractive optical element 62 for circular illumination has a function of converting the incident light beam of rectangular shape into the light beam of circular shape. Therefore, the circular light beam formed by the diffractive optical element 62 forms the circular illumination area centering on the optical axis AX in the incident surface of the fly's eye lens 8 via the zoom lens 7. As a result, a circular secondary light source centering on the optical axis AX is also formed on the rear focal plane of the fly's eye lens 8. In this case, the outer diameter of the circular secondary light source can be appropriately changed by changing the focal length f2 of the zoom lens 7.

In addition, the 2-pole aperture stop 9, the 8-pole aperture stop 9a, or the like correspond to the retraction from the illumination light path of the micro fly's eye 4 and the setting of the illumination light path of the diffractive optical element 62 for circular illumination. The switch from the modified four-pole aperture diaphragm 9b to the circular aperture diaphragm 9c is performed. The circular aperture diaphragm 9c is one circular aperture diaphragm selected from two circular aperture diaphragms 407 and 408 and has an opening of a size corresponding to the secondary light source of circular shape. In this way, the micro fly's eye 4 is retracted from the illumination light path and the circularly-shaped diffractive optical element 62 is used, thereby reducing the amount of light based on the luminous flux from the light source 1 so that the circular shape 2 can be reduced. A circular illumination can be normally performed, forming a secondary light source and suppressing the loss of light quantity in the aperture stop which limits the luminous flux from a secondary light source.

Hereinafter, operation | movement of lighting switching etc. in Example 1 is demonstrated concretely. First, information about various masks to be sequentially exposed in accordance with the step and repeat method or the step and scan method is input to the control system 21 via an input means 20 such as a keyboard. The control system 21 stores information, such as the optimum line width (resolution) and depth of focus, of various masks in a part of the internal memory, and responds to the input from the input means 20 to the first drive system 22 to the first. 5 An appropriate control signal is supplied to the drive system 26.

That is, in the case of dipole illumination based on the optimal resolution and the depth of focus, the third drive system 24, based on the instruction from the control system 21, causes the diffraction optical element 6 for dipole illumination to be illuminated in the illumination optical path. Determine your location. Then, in order to obtain a bipolar secondary light source having a desired size (outer diameter) and shape (ring band ratio) on the rear focal plane of the fly's eye lens 8, the second drive system 23 controls the control system 21. The magnification of the apocal zoom lens 5 is set on the basis of the instruction from), and the fourth drive system 25 sets the focal length of the zoom lens 7 on the basis of the instruction from the control system 21. In addition, in order to restrict the secondary light source having a bipolar shape in a state in which light loss is satisfactorily suppressed, the fifth drive system 26 rotates the turret based on the command from the control system 21, and the desired two-pole opening. Position the iris in the illumination light path.

In this way, the secondary light source of the bipolar shape can be formed on the basis of the light beam from the light source 1, and almost no light amount is lost. As a result, the light aperture is almost at the aperture stop limiting the light flux from the secondary light source. The dipole illumination can be performed without losing the weight. In dipole illumination based on a bipolar secondary light source, the resolution of the projection optical system PL can be improved mainly with respect to the pattern shape along one direction, while securing a predetermined depth of focus.

If necessary, by changing the magnification of the apocal zoom lens 5 by the second drive system 23 or by changing the focal length of the zoom lens 7 by the fourth drive system 25, The size and annular ratio of the bipolar secondary light source formed on the rear focal plane of the fly's eye lens 8 can be appropriately changed. In this case, the turret rotates in accordance with the change in the size of the bipolar secondary light source and the annular band ratio, so that the dipole aperture diaphragm having the desired size and the annular band ratio is selected and positioned in the illumination optical path. In this way, various dipole illuminations can be performed by appropriately changing the size and annular ratio of the dipole-shaped secondary light source without almost losing the amount of light in forming and limiting the dipole-shaped secondary light source. .

In addition, when performing normal circular illumination based on the optimal resolution and depth of focus, the 1st drive system 22 evacuates the micro fly eye 4 from the illumination optical path based on the instruction | command from the control system 21. Moreover, the 3rd drive system 24 positions the diffraction optical element 62 for circular illumination normally in an illumination optical path based on the command from the control system 21. As shown in FIG. Then, in order to obtain a circular secondary light source having a desired size (outer diameter) in the rear focal plane of the fly's eye lens 8, the second drive system 23 is based on the command from the control system 21. The magnification of the focal zoom lens 5 is set, and the fourth drive system 25 sets the focal length of the zoom lens 7 based on the command from the control system 21.

In addition, in order to restrict the circular secondary light source in a state in which light loss is satisfactorily suppressed, the fifth drive system 26 rotates the turret based on the command from the control system 21, and the desired circular aperture stop is provided. Position in the illumination path. In addition, when using the iris stop which can change a circular aperture diameter continuously, the 5th drive system 26 sets the aperture diameter of an iris stop based on the command from the control system 21. As shown in FIG. In this way, the secondary light source of a circular shape can be formed on the basis of the light beam from the light source 1, and almost no light amount is lost. As a result, the amount of light loss is reduced in the aperture stop which limits the light flux from the secondary light source. Usually, circular illumination can be performed, suppressing favorably.

In addition, if necessary, by changing the focal length of the zoom lens 7 by the fourth drive system 25, the size of the circular secondary light source formed on the rear focal plane of the fly's eye lens 8 can be adjusted. You can change it accordingly. In this case, the turret rotates in accordance with the change in the size of the circular secondary light source so that a circular aperture stop having an opening of a desired size is selected and positioned in the illumination light path. In this manner, various normal circular illuminations can be performed by appropriately changing the sigma value while suppressing light loss in formation and limitation of the circular secondary light source.

As described above, in the first embodiment described above, modified illumination such as dipole illumination and ordinary circular illumination can be performed while satisfactorily suppressing light loss in the aperture stop for limiting the secondary light source. In addition, by a simple operation of changing the magnification of the apocal zoom lens or changing the focal length of the zoom lens, it is possible to change the parameters of the deformed illumination and the normal circular illumination while suppressing the loss of the light amount in the aperture stop. . Therefore, by changing the type and parameter of the modified illumination as appropriate, it is possible to obtain the resolution and depth of focus of the projection optical system suitable for the fine pattern to be subjected to exposure projection. As a result, good projection exposure with high throughput can be performed based on high exposure illuminance and good exposure conditions.

(Example 2)

7 is a diagram schematically showing a configuration of an exposure apparatus including an illumination optical device according to Embodiment 2 of the present invention. Example 2 has a structure similar to Example 1. However, in Embodiment 1, the micro fly's eye 4 is disposed between the bending mirror 3 and the apocal zoom lens 5 and the diffractive optical element (B) between the apocal zoom lens 5 and the zoom lens 7. 6 (60 to 62) are arranged, but in the second embodiment, the diffractive optical elements 6 (60 and 61) are arranged between the bending mirror 3 and the apocal zoom lens 5 and the apocal zoom lens. The micro fly eye 4 is disposed between the 5 and the zoom lens 7. That is, in Example 1 and Example 2, only the point to which the arrangement position of a micro fly's eye and a diffractive optical element is reversed basically differs. In Example 2, unlike Example 1, there is no diffractive optical element for circular illumination.

As described above, in Example 1, the micro fly's eye 4 and the apocal zoom lens 5 convert the luminous flux from the light source 1 into a luminous flux having various angular components with respect to the optical axis AX. An angular luminous flux forming means for incident on the diffraction surface of 6 (60, 61) is constituted. Here, the micro fly's eye 4 constitutes a divergent light beam forming element for converting a substantially parallel luminous flux from the light source 1 into a luminous flux diverging at various angles with respect to the optical axis AX. In addition, the diffractive optical elements 6 (60, 61) and the zoom lens 7 fly a plurality of (two) illumination regions symmetrically eccentric with respect to the optical axis AX based on the incident light beam having various angle components. An illumination region forming means for forming on the incident surface of the eye lens 8 is configured. Here, the diffractive optical elements 6 (60, 61) constitute a luminous flux converting element for converting the incident luminous flux into plural (two) luminous fluxes.

In contrast, in Example 2, the diffractive optical elements 6 (60, 61) and the apocal zoom lens 5 have a plurality of (2) beams in which the beams from the light source 1 are eccentric with respect to the optical axis AX. The light beam shape conversion means for converting the light into the incident surface of the micro fly's eye 4 from the inclined direction with respect to the optical axis AX is configured. Here, the diffractive optical elements 6 (60, 61) constitute a luminous flux converting element for converting substantially parallel luminous flux from the light source 1 into plural (two) luminous fluxes. In addition, the micro fly's eye 4 and the zoom lens 7 enter a plurality of (two) illumination regions symmetrically eccentrically with respect to the optical axis AX based on the incident light beam in the oblique direction. Illumination area formation means for forming on a surface is formed. Here, the micro fly's eye 4 constitutes a wavefront dividing element for wavefront dividing the incident light beam to form a plurality of light sources.

Thus, in Example 1 and Example 2, the arrangement position of the micro fly eye 4 and the diffraction optical element 6 (60, 61) is reversed. However, the partial optical system from the micro fly's eye 4 to the zoom lens 7 in the first embodiment, and the diffractive optical elements 6 (60, 61) to the zoom lens 7 in the second embodiment. The partial optical system of is optically equivalent. Therefore, the partial optical system from the micro fly's eye 4 to the fly's eye lens 8 in Example 1 and the diffraction optical elements 6 (60, 61) to the fly's eye lens 8 in Example 2 The partial optical system up to) is a secondary light source forming means for forming a plurality of surface light sources symmetrically eccentric with respect to the optical axis AX in the illumination pupil that is conjugated with the pupil of the projection optical system PL based on the light beam from the light source 1. It is common in that it constitutes.

The second embodiment will be briefly described below by paying attention to differences from the first embodiment. In Embodiment 2, the apocal zoom lens 5 is configured to optically connect the entrance surface of the diffractive optical element 6 and the micro fly's eye 4 almost optically. In addition, the zoom lens 7 has a relationship between the rear focal plane of the micro fly's eye 4 and the incident surface of the fly's eye lens 8 substantially in a Fourier transform relationship. Therefore, the light which has passed through the diffractive optical element 6 for dipole illumination forms two point images as shown in Fig. 3B on the pupil plane of the apocal zoom lens 5.

The light from these two points becomes parallel light via the apocal zoom lens 5 and enters the incident surface of the micro fly's eye 4 from the inclination direction with respect to the optical axis AX. As a result, in the second embodiment, similarly to the first embodiment, the rear focal plane of the zoom lens 7 extends to the incidence plane of the fly's eye lens 8 on the optical axis AX as shown in Fig. 4B. Two illumination regions symmetrically eccentric with respect to, i.e., a dipole-shaped illumination region are formed. Then, on the rear focal plane of the fly's eye lens 8, a secondary light source having a bipolar shape is formed on the basis of the light beam from the light source 1 with almost no light loss. In addition, even in the aperture diaphragm 9 disposed in the vicinity of the rear focal plane of the fly's eye lens 8, almost no light loss occurs. Further, by appropriately changing the magnification of the apocal zoom lens 5 and the focal length of the zoom lens 7, the size and shape (ring ratio) of the bipolar secondary light source can be changed. Same as Example 1.

(Modifications of Example 1 and Example 2)

8 is a diagram schematically showing the configuration of main parts of a modification of the first embodiment and the second embodiment. The modification of FIG. 8 has a structure similar to Example 1 and Example 2. FIG. However, in Example 1 and Example 2, the wavefront split type fly's eye lens is used as the optical integrator. However, in the modification of FIG. 8, only the internal reflective rod type optical integrator is used as the optical integrator. Doing. In addition, in FIG. 8, illustration of the element of a light source side, the element of a drive control relationship, etc. are abbreviate | omitted rather than the zoom lens 7 of Example 1 and Example 2. In FIG. Hereinafter, a modification is demonstrated, paying attention to the difference of Example 1 and Example 2.

In the modification, in response to the use of the rod integrator 8a instead of the fly's eye lens 8, a condenser lens 7a is placed in the optical path between the zoom lens 7 and the rod integrator 8a, and the condenser The imaging optical system 10a is provided instead of the optical system 10, and the aperture stop for limiting the secondary light source is removed. Here, the composite optical system composed of the zoom lens 7 and the condenser lens 7a is a variation of the diffractive surface of the diffractive optical elements 6 (60 to 62) and the rod integrator 8a in the modification corresponding to the first embodiment. In the modified example corresponding to Example 2, the rear focal plane of the micro fly's eye 4 and the incident surface of the rod integrator 8a are optically almost conjugated. In addition, the imaging optical system 10a optically connects the exit surface of the rod integrator 8a and the mask M optically in conjugate space.

The rod integrator 8a is an inner surface reflective glass rod made of a glass material such as quartz glass or fluorite, and passes through a condensing point using a total internal reflection on the inner and outer surfaces, that is, the inner surface of the rod. Form a number of light source images according to the number of inner surface reflections along a plane parallel to the surface. Here, most of the light source image formed is a virtual image, but only the light source image of a center (condensing point) becomes a real image. That is, the luminous flux incident on the rod integrator 8a is divided in the angular direction by the inner surface reflection, and a secondary light source is formed on the light source along the plane parallel to the incident surface after passing through the focusing point. .

The light beam from the secondary light source formed on the incidence side by the rod integrator 8a is superimposed on the exit surface, and then uniformly illuminates the mask M in which a predetermined pattern is formed via the imaging optical system 10a. As described above, the imaging optical system 10a optically connects the exit surface of the rod integrator 8a and the mask M (the wafer W to be advanced) almost optically. Therefore, on the mask M, a rectangular illumination region similar to the cross-sectional shape of the rod integrator 8a is formed. Thus, also in the modification, similarly to Example 1 and Example 2, modified illumination, such as dipole illumination, and normal circular illumination can be performed, suppressing light loss favorably.

In the exposure apparatus according to each of the embodiments described above, the mask is illuminated by an illumination optical device (lighting step), and the exposure pattern formed on the mask is scanned and exposed to the photosensitive substrate by using a projection optical system (exposure step), Micro devices (semiconductor elements, imaging elements, liquid crystal display elements, thin film magnetic heads, etc.) can be manufactured. Hereinafter, the semiconductor device as a micro device is obtained by forming a predetermined circuit pattern on a wafer or the like as a photosensitive substrate using the exposure apparatus of Example 1 shown in FIG. 1 or the exposure apparatus of Example 2 shown in FIG. 7. An example of the method at the time will be described with reference to the flowchart of FIG. 9.

First, in step 301 of FIG. 9, a metal film is deposited on one lot of wafers. In a next step 302, photoresist is applied onto the one lot of metal film on the wafer. Thereafter, in step 303, the image of the pattern on the mask is sequentially passed through the projection optical system (projection optical module) to each shot region of the one lot of wafers using the exposure apparatus shown in FIG. 1 or 7. Exposure is transferred. Thereafter, in step 304, the development of the photoresist on the one lot of wafers is performed, and then, in step 305, etching is performed on the one lot of wafers with the resist pattern as a mask to correspond to the pattern on the mask. Circuit patterns are formed in each shot region on each wafer. Thereafter, a device such as a semiconductor element is manufactured by forming the circuit pattern of the upper layer or the like. According to the semiconductor device manufacturing method described above, a semiconductor device having a very fine circuit pattern can be obtained with good throughput.

In each of the above-described embodiments, the diffractive optical elements 6 (61 to 62) as the light beam conversion elements can be configured to be positioned in the illumination optical path by, for example, a turret method. For example, the above-mentioned diffraction optical element 6 (61-62) can also be inserted / separated and switched using the well-known slider mechanism.

In addition, in each Example mentioned above, the shape of the micro lens which comprises the micro fly eye 4 is set to the regular hexagon. This is because a regular hexagon is selected as a polygon close to a circle because a circular micro lens cannot be densely arranged and loss of light occurs. However, the shape of each microlens constituting the micro fly's eye 4 is not limited to this, and other suitable shapes including, for example, rectangular shapes can be used. In each of the above-described embodiments, the refractive power of the microlenses constituting the micro fly's eye 4 is called the refractive power, but the refractive power of the microlenses may be negative.

In addition, although the apocal zoom lens 5 is used in Example 1 mentioned above, a circular light beam is made into the rectangular beam in front of the micro fly eye 4 using a focal zoom lens instead of an apocal zoom lens. The arrangement which arrange | positions the diffraction optical element for converting into the structure is also possible. In addition, although the one fly eye lens 8 is used in each embodiment mentioned above, this invention is applicable also to the double fly eye system using two fly-eye lenses. In addition, in Example 1 mentioned above, although the diffraction optical element 62 is positioned in the illumination optical path at the time of performing ordinary circular illumination, use of this diffraction optical element 62 can also be omitted.

In the above-described embodiments, the micro fly's eye 4 is used as the divergent light beam forming element. However, for example, a fly's eye lens, a diffractive optical element, or the like may be used as necessary. In addition, although the diffraction optical element is used as the light beam conversion elements 6 (61-62) in each above-mentioned embodiment, it is not limited to this, For example, refractive optical elements, such as a micro fly's eye and a microlens prism, can also be used. . However, a detailed description of the diffractive optical element that can be used in the present invention is disclosed in US Patent No. 5,850,300.

In addition, although each embodiment mentioned above demonstrated this invention taking the projection exposure apparatus provided with the illumination optical apparatus as an example, what can apply this invention to the general illumination optical apparatus for uniformly illuminating the to-be-exposed surface other than a mask is Obvious.

In each of the above-described embodiments, the condenser optical system 10 as the light guide optical system condenses the light from the secondary light source formed at the position of the aperture stop 9 to illuminate the mask M in a superimposed manner. However, the illumination visual field stop (mask blind) and the relay optical system which form the image of this illumination visual field stop on the mask M may be arrange | positioned between the condenser optical system 10 and the mask M. FIG. In this case, the light guiding optical system is composed of a condenser optical system 10 and a relay optical system, and the condenser optical system 10 condenses the light from the secondary light source formed at the position of the aperture diaphragm 9 to overlap the illumination field stop. The illumination of the relay system forms an image of the opening of the illumination field stop on the mask M. FIG. The above is the same also in the modified example of each Example.

In the above-described embodiments, the fly's eye lens 8 is formed by integrating a plurality of element lenses. However, the fly's eye lens 8 may be a micro fly's eye. The micro fly's eye is provided with a plurality of micro lens surfaces in a matrix form by a method such as etching on a light transmissive substrate. In terms of forming a plurality of light source images, there is practically no functional difference between the fly's eye lens and the micro fly's eye, but the size of the aperture of one element lens (microlens) can be made very small. The micro fly's eye is advantageous in that it is possible to significantly reduce the thickness, and to make the thickness in the optical axis direction extremely thin.

In each of the above-described embodiments, the aperture stop 9 for restricting the luminous flux of the secondary light source is arranged near the rear focal plane of the fly's eye lens 8. However, it is also possible to omit the arrangement of the aperture stops so as not to limit the luminous flux of the secondary light source.

For example, when the cross-sectional area of each lens element constituting the fly's eye lens is set sufficiently small, as in the case where the fly's eye lens 8 is a micro fly's eye as described above, the secondary aperture is omitted and the secondary aperture is omitted. The configuration which does not restrict the luminous flux of a light source at all is also possible.

By the way, in each embodiment mentioned above, since the wavelength of 180 nm or more exposure light, such as KrF excimer laser (wavelength: 248 nm) and ArF excimer laser (wavelength: 193 nm), is used, a diffraction optical element For example, it can form with quartz glass. In the case where a wavelength of 200 nm or less is used as the exposure light, for example, when a F ₂ laser (wavelength: 157 nm) that supplies exposure light having a wavelength in a vacuum ultraviolet region is used, the diffractive optical element is doped with fluorite and fluorine. Quartz glass, quartz glass doped with fluorine and hydrogen, quartz glass having a structure crystal temperature of 1200 K or less and an OH group concentration of 1000 ppm or more, quartz having a structure crystal temperature of 1200 K or less and a hydrogen molecule concentration of 1 × 10 ¹⁷ molecules / cm 3 or more Groups of glass, quartz glass having a structure crystal temperature of 1200 K or less and a chlorine concentration of 50 ppm or less, and a quartz glass having a structure crystal temperature of 1200 K or less and a hydrogen molecule concentration of 1 × 10 ¹⁷ molecules / cm 3 or more and a chlorine concentration of 50 ppm or less It is preferable to form with the material chosen from.

Moreover, regarding the quartz glass whose structure crystal temperature is 1200K or less and OH group concentration is 1000 ppm or more, it is disclosed by Unexamined-Japanese-Patent No. 2770224 by this applicant, The structure crystal temperature is 1200K or less and hydrogen molecule concentration is 1 Quartz glass having a size of at least 10 × 10 ¹⁷ molecules / cm 3, quartz glass having a structure crystal temperature of 1200 K or less and a chlorine concentration of 50 ppm or less, and a structure crystal temperature of 1200 K or less, and a hydrogen molecule concentration of 1 × 10 ¹⁷ molecules / cm 3 or more, and chlorine About quartz glass whose density | concentration is 50 ppm or less, it is disclosed by Unexamined-Japanese-Patent No. 2936138 by this applicant.

As described above, in the illumination optical apparatus according to each embodiment of the present invention, modified illumination such as dipole illumination and ordinary circular illumination, while satisfactorily suppressing the amount of light loss in the aperture stop for limiting the secondary light source, are preferably used. I can do it. As a result, the resolution of the projection optical system can be improved for a specific pattern shape while securing a predetermined depth of focus. In addition, by a simple operation of changing the magnification of the apocal zoom lens or changing the focal length of the zoom lens, it is possible to change the parameter of the modified illumination while satisfactorily suppressing the light amount loss in the aperture stop.

Therefore, in the exposure apparatus equipped with the illumination optical apparatus according to each embodiment of the present invention, the type and parameters of the modified illumination can be appropriately changed to obtain the resolution and the depth of focus of the projection optical system suitable for the fine pattern to be subjected to exposure projection. . As a result, good projection exposure with high throughput can be performed based on high exposure illuminance and good exposure conditions. Moreover, in the exposure method which exposes the pattern of the mask arrange | positioned on the to-be-exposed surface using the illumination optical apparatus of this invention on a photosensitive board | substrate, since a projection exposure can be performed based on favorable exposure conditions, a favorable microdevice is manufactured. can do.

As mentioned above, although the invention made by this inventor was demonstrated concretely according to the said Example, this invention is not limited to the said Example and can be variously changed in the range which does not deviate from the summary.

Claims (22)

In the illumination optical apparatus for illuminating the said mask, it is used for the projection exposure apparatus which transfers the image of the pattern on a mask on a board | substrate via a projection optical system, Light source means for supplying a light beam having an exposure wavelength; A secondary light source forming means for forming two surface light sources substantially symmetrically symmetrical with respect to a reference optical axis in the illumination pupil that is conjugate with the pupil of the projection optical system based on the light beam from the light source means; Having a displacement optical system for continuously changing the distance between the two surface light sources from the reference optical axis, the size of each of the two surface light sources, and the azimuth angle which is the angle at which the two surface light sources are expected from the reference optical axis Illumination optical device, characterized in that. The method of claim 1, The variable displacement optical system comprises two variable displacement optical systems. The method of claim 2, And said secondary light source forming means comprises a luminous flux converting element for converting the incident luminous flux into two luminous fluxes. The method of claim 3, wherein And said luminous flux converting element is interchangeable with another luminous flux converting element. The method of claim 1, The secondary light source forming means, An angular luminous flux forming means for converting the luminous flux from the light source means into a luminous flux having various angular components with respect to a reference optical axis and making it enter the first predetermined surface; Illumination region forming means for forming on the second predetermined surface two illumination regions symmetrically symmetrical with respect to the reference optical axis based on the light beam having the various angular components incident on the first predetermined surface; An optical integrator for forming a bipolar secondary light source having a light intensity distribution substantially the same as the two illumination regions based on the light beams from the two illumination regions formed on the second predetermined surface. Provided with Further comprising a light guiding optical system for introducing the light beam from the optical integrator into the irradiated surface Illumination optical device, characterized in that. The method of claim 5, The angular beam forming means, A divergent luminous flux forming element for converting a substantially parallel luminous flux from said light source means into luminous flux diverging at various angles with respect to said reference optical axis; Having a first optical system for collecting and guiding the divergent luminous flux formed through the divergent luminous flux forming element to the first predetermined surface Illumination optical device, characterized in that. The method of claim 6, The first optical system has a first variable optical system for changing its width without changing the center height of the plurality of surface light sources formed as the secondary light source, The first shifting optical system constitutes at least a part of the shifting optical system Illumination optical device, characterized in that. The method of claim 7, wherein The divergent light beam forming element has an optical element array having a plurality of unit optical elements arranged in a two-dimensional shape, Said first variable optical system having an afocal zoom lens that optically connects a plurality of condensing points of the light beam from said light source means by said optical element array and said first predetermined surface in optical proximity; Illumination optical device, characterized in that. The method of claim 5, The illumination region forming means, A light beam conversion element disposed in the vicinity of the first predetermined surface to convert the incident light beam into a plurality of light beams; Having a second optical system for guiding the luminous flux from said luminous flux converting element to said second predetermined surface Illumination optical device, characterized in that. The method of claim 9, The luminous flux conversion element forms a plurality of illumination regions eccentric with respect to the reference optical axis in the far field, Wherein said second optical system forms said plurality of illumination regions formed in said farfield on said second predetermined surface; Illumination optical device, characterized in that. The method of claim 9, The second optical system has a second variable optical system for changing the outer diameters of the plurality of surface light sources formed as the secondary light source while maintaining similar shapes to each other, The second variable optical system constitutes at least a part of the variable optical system Illumination optical device, characterized in that. The method of claim 11, The luminous flux converting element freely inserted / separated with respect to the illumination light path and having a diffractive optical element having a diffraction surface positioned on the first predetermined surface, The second variable optical system forms a diffractive surface of the diffractive optical element and the second predetermined surface substantially in a Fourier transform relationship Illumination optical device, characterized in that. The method of claim 1, The secondary light source forming means, Luminous flux shape converting means for converting the luminous flux from said light source means into two luminous fluxes eccentric with respect to a reference optical axis, and causing light from said two luminous fluxes to enter said first predetermined plane from an oblique direction with respect to said reference optical axis; Illumination region forming means for forming, on the second predetermined surface, two illumination regions symmetrically symmetrical with respect to the reference optical axis based on the light beam in the inclined direction incident on the first predetermined surface; An optical integrator for forming a bipolar secondary light source having a light intensity distribution substantially the same as the two illumination regions, based on the light beams from the two illumination regions formed on the second predetermined surface, And further provided with a light guide optical system for guiding the luminous flux from the optical integrator to the mask. Illumination optical device, characterized in that. The method of claim 13, The light beam shape conversion means, A light beam conversion element for converting a substantially parallel light beam from the light source means into a plurality of light beams, Having a third optical system for guiding the luminous flux from said luminous flux converting element to said first predetermined surface Illumination optical device, characterized in that. The method of claim 14, The luminous flux converting element forms a plurality of luminous fluxes eccentric with respect to the reference optical axis in farfield, Wherein the third optical system forms the plurality of luminous fluxes formed in the far field on its pupil plane Illumination optical device, characterized in that. The method of claim 14, The third optical system has a third variable optical system for changing its width without changing the center height of the plurality of surface light sources formed as the secondary light source, The third variable optical system constitutes at least a part of the variable optical system Illumination optical device, characterized in that. The method of claim 16, The luminous flux conversion element has a diffractive optical element freely inserted / separated with respect to the illumination light path, Wherein said third variable optical system has an apocal zoom lens that optically couples a diffractive surface of said diffractive optical element and said first predetermined surface in an optically conjugate manner; Illumination optical device, characterized in that. The method of claim 13, The illumination region forming means, A wavefront dividing element for wavefront dividing the incident light beam onto the first predetermined surface to form a plurality of light sources; Having a fourth optical system for collecting divergent light fluxes from a plurality of light sources formed through the wavefront dividing element and guiding them to the second predetermined surface Illumination optical device, characterized in that. The method of claim 18, The fourth optical system has a fourth variable optical system for changing the outer diameters of the plurality of surface light sources formed as the secondary light source while maintaining similar shapes to each other, The fourth shifting optical system constitutes at least a part of the shifting optical system Illumination optical device, characterized in that. The method of claim 19, The wavefront dividing element has an optical element array having a plurality of unit optical elements arranged in a two-dimensional shape with an incident surface disposed near the first predetermined surface, Wherein the fourth variable optical system connects the incidence surface of the optical element array and the second predetermined surface in an optically substantially conjugate relationship. Illumination optical device, characterized in that. The illumination optical device according to any one of claims 1 to 20, Provided with a projection optical system for projecting and exposing the pattern of the mask set on said irradiated surface onto a photosensitive substrate An exposure apparatus characterized by the above-mentioned. An exposure step of exposing the pattern of the mask on the photosensitive substrate by the exposure apparatus according to claim 21; And a developing step of developing the photosensitive substrate exposed by the exposure step. Method for producing a micro device, characterized in that.