JP2011103465A - Lighting optical device, exposure device, and control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the condensation of light from optical elements in a narrow region on a surface of a following optical member when the light from a plurality of optical elements is used. <P>SOLUTION: A lighting device 2 for lighting a surface of a reticle by using the light from a light source 7 includes: a plurality of mirror elements 3 which are two-dimensionally arranged on the light path; a drive 4 for driving the plurality of mirror elements 3 and independently controlling each of the light deflection directions; and a relay optical system 14 which introduces the light deflected by the plurality of mirror elements 3 into an incident surface of a fly-eye lens 15. The relay optical system 14 prevents the light in the same direction from being condensed in one point at the incident surface 22I when the light deflection directions in the plurality of mirror elements 3 are aligned to be identical. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an illumination technique for illuminating an irradiated surface using a plurality of optical elements capable of controlling the light deflection direction, a control technique for the plurality of optical elements, an exposure technique using the illumination technique, and this exposure technique. The present invention relates to a device manufacturing technique to be used.

  For example, an exposure apparatus such as a batch exposure type projection exposure apparatus such as a stepper used in a lithography process for manufacturing an electronic device (microdevice) such as a semiconductor element or a scanning exposure type projection exposure apparatus such as a scanning stepper is used. And an illumination optical system for illuminating the reticle (mask) under various illumination conditions and with a uniform illuminance distribution. A conventional illumination optical system switches, for example, a plurality of diffractive optical elements according to illumination conditions and arranges them on the optical path of the illumination light, and distributes the light amount distribution on the pupil plane as a circular region, an annular region, or a plurality of poles. In such a region, the distribution is set so that the amount of light increases. In this configuration, it is necessary to provide approximately the same number of diffractive optical elements as the number of illumination conditions.

  Therefore, a movable multi-mirror spatial light modulator having a large number of minute mirror elements arranged in an array and having a variable tilt direction and tilt angle, and a fly that collects reflected light from the plurality of mirror elements. An illumination optical system including an eye lens (fly eye integrator) has been proposed (see, for example, Patent Document 1). According to this illumination optical system, the light amount distribution on the pupil plane near the exit surface of the fly-eye lens can be substantially arbitrarily distributed by controlling the tilt direction and tilt angle of the many mirror elements of the spatial light modulator. Can be set.

JP 2002-353105 A

In general, a spatial light modulator included in a conventional illumination optical system is such that the reflecting surfaces of all mirror elements are parallel when the power is off. When illumination light is irradiated in this state, the reflected light from all mirror elements is condensed on a specific lens element of the fly-eye lens, and the optical material or antireflection film of the lens element may be damaged. There is.
In view of such circumstances, an object of the present invention is to make it difficult for light from a plurality of optical elements to be collected in a narrow area on the surface of a subsequent optical member when using light from a plurality of optical elements. To do.

  According to the first aspect of the present invention, in the illumination optical device that illuminates the irradiated surface using light from the light source, the plurality of optical elements arranged two-dimensionally with respect to the optical path of the light, and the A drive mechanism that drives each of the plurality of optical elements and individually controls the deflection direction of the light; and an optical system that guides the light deflected by each of the plurality of optical elements to a region within a predetermined plane. The optical system is configured to condense the light through the plurality of optical elements at one point on the predetermined surface when the deflection directions of the light in the plurality of optical elements are aligned in the same direction. An obstructing illumination optical device is provided.

  Further, according to the second aspect of the present invention, the plurality of optical elements that are two-dimensionally arranged with respect to the optical path of the light that illuminates the illuminated surface and are individually driven to control the deflection direction of the light. A method of controlling a spatial light modulator having an element, wherein the light from the plurality of optical elements is guided to a predetermined surface through an optical system, and the plurality of optical elements of the spatial light modulator are connected to the predetermined surface. Thus, a control method for controlling the light so as not to be condensed at one point is provided.

  According to the third aspect of the present invention, there is provided an exposure apparatus that includes the illumination optical apparatus according to the present invention for illuminating a predetermined pattern and that exposes a substrate through the predetermined pattern. Further, according to the fourth aspect of the present invention, an exposure process of exposing the substrate through the predetermined pattern using the exposure apparatus according to the present invention, and developing the substrate, corresponding to the predetermined pattern There is provided a device manufacturing method including a developing step of forming a mask layer to be formed on the surface of the substrate, and a processing step of processing the surface of the substrate through the mask layer.

  According to the present invention, even if the light from the plurality of optical elements is a substantially parallel light flux, the light is not condensed on a predetermined area on the predetermined surface, for example, one point smaller than the minimum area that does not cause damage to the optical member. . Therefore, by setting the predetermined surface as the surface of the optical member subsequent to the plurality of optical elements, it becomes difficult for the light from the plurality of optical elements to be collected in a narrow area on the surface of the optical member. Damage is suppressed.

It is a figure which shows schematic structure of the exposure apparatus of an example of embodiment. FIG. 2 is an enlarged perspective view showing a part of the spatial light modulator 13 in FIG. 1. (A) is a figure which shows the inclination angle of the mirror element of the spatial light modulator 13 at the time of dipole illumination, (B) is a figure which shows the secondary light source at the time of dipole illumination, (C) is the spatial light at the time of power-off The figure which shows the optical path of the illumination light from the modulator 13, (D) is a figure which shows the condensing area | region of the entrance plane of the fly eye lens 15 of FIG.3 (C). (A) is a diagram showing another secondary light source during dipole illumination, (B) is a diagram showing a secondary light source during normal illumination, (C) is a diagram showing a secondary light source during annular illumination, D) is a diagram showing a secondary light source during quadrupole illumination. (A) is a figure which shows an example of the state which condenses the light from the spatial light modulator 13 to the minimum area | region, (B) is a figure which shows the entrance plane of the fly eye lens 15 of FIG. 5 (A), (C). FIG. 6 is a diagram showing another example of a state in which illumination light from the spatial light modulator 13 is condensed in the minimum region, and FIG. 5D is a diagram showing an incident surface of the fly-eye lens 15 in FIG. 4 is a flowchart showing an example of an exposure operation using the spatial light modulator 13. (A) And (B) is a figure which shows the principal part of the illuminating device of the other example of embodiment, respectively. It is a flowchart which shows an example of the manufacturing process of an electronic device.

An example of an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 shows a schematic configuration of an exposure apparatus EX of the present embodiment. The exposure apparatus EX is, for example, a scanning exposure type exposure apparatus (projection exposure apparatus) composed of a scanning stepper (scanner). In FIG. 1, the exposure apparatus EX includes an illumination apparatus 2 that illuminates a reticle surface (irradiated surface) that is a pattern surface of a reticle R (mask) with exposure illumination light (exposure light) IL. The illumination device 2 includes a light source 7 that emits pulsed illumination light IL, and an illumination optical system ILS that illuminates an illumination area 36 on a reticle surface (illuminated surface) with the illumination light IL from the light source 7. The exposure apparatus EX further includes a reticle stage RST that positions and moves the reticle R, a projection optical system PL that projects an image of the pattern of the reticle R onto the surface of the wafer W (substrate), and positioning and movement of the wafer W. It includes a wafer stage WST to be performed, a main control system 30 composed of a computer that controls the overall operation of the apparatus, and various control systems. Hereinafter, the Z axis is set in parallel to the optical axis of the projection optical system PL, and the Y axis is set in a direction parallel to the plane of FIG. 1 in a plane perpendicular to the Z axis (substantially a horizontal plane in the present embodiment). In the following description, the X axis is set in the direction perpendicular to the paper surface. In the present embodiment, the scanning direction of the reticle R and the wafer W at the time of exposure is a direction parallel to the Y axis (Y direction), and the illumination area 36 is a rectangle elongated in the X direction (non-scanning direction). In addition, the rotational directions (inclination directions) around the axes parallel to the X axis, the Y axis, and the Z axis will be described as the θx direction, the θy direction, and the θz direction.

  As the light source 7, an ArF excimer laser light source that emits pulsed laser light having a wavelength of 193 nm at a frequency of about 4 to 6 kHz is used. As the light source 7, a KrF excimer laser light source that supplies a laser beam having a wavelength of 248 nm or a harmonic generator that generates harmonics of a laser beam output from a solid-state laser light source (YAG laser, semiconductor laser, etc.) is also used. it can. A power source unit 32 is connected to the light source 7. The main control system 30 supplies a light emission trigger pulse TP instructing the timing of light emission and the amount of light (pulse energy) to the power supply unit 32. The power supply unit 32 causes the light source 7 to emit pulses in synchronization with the light emission trigger pulse TP.

  Illumination light IL, which is a substantially parallel light beam emitted from the light source 7 and made of linearly polarized laser light, enters the beam expander 8, and its cross-sectional shape is enlarged to a predetermined shape. The illumination light IL emitted from the beam expander 8 is a half-wave plate 9 (polarization control member) for rotating the polarization direction of the illumination light IL by a plurality of predetermined angles in the illumination optical system ILS having the optical axis AXI. ), A drive unit 33 that rotates the half-wave plate 9 under the control of the main control system 30, and two wedge-shaped prisms 10a and 10b for converting the illumination light IL into random polarization (non-polarization). It passes through a polarizing optical system having a depolarizer 10 consisting of The detailed configuration and operation of the polarizing optical system including the half-wave plate 9 and the depolarizer 10 are disclosed in International Publication No. 2004/051717.

The illumination light IL that has passed through the depolarizer 10 is reflected by the mirror 11 in the + Y direction, and then, along the optical axis AXI, is incident on the incident surface 12d of the prism 12 having the entrance surface 12d and the exit surface 12e perpendicular to the optical axis AXI. Incident. The prism 12 is made of an optical material such as fluorite (CaF ₂ ) or quartz that transmits the illumination light IL. As an example, the prism 12 includes a first reflecting surface 12a that intersects the incident surface 12d clockwise at about 60 ° about an axis parallel to the X axis, and a surface parallel to the first reflecting surface 12a and the XZ plane. The second reflection surface 12b is substantially symmetrical with respect to the XY plane, and the transmission surface 12c is parallel to the XY plane and orthogonal to the incident surface 12d (exit surface 12e).

  Further, in the vicinity of the prism 12 (on the transmission surface 12c side), a large number of mirror elements 3 each having a variable tilt angle arranged in a two-dimensional array, and driving for driving these mirror elements 3 A spatial light modulator 13 having a unit 4 is installed. A large number of mirror elements 3 of the spatial light modulator 13 are disposed substantially parallel to and close to the transmission surface 12c as a whole. Further, the reflection surfaces of the mirror elements 3 can be controlled almost continuously within a predetermined variable range in inclination angles in the θx direction and the θy direction (around two orthogonal axes). As an example, at the center within the variable range, the reflecting surface of each mirror element 3 is substantially parallel to the transmitting surface 12c. Further, in a state where the drive unit 4 of the spatial light modulator 13 is turned off and reset when the power is turned on, the reflecting surfaces of all the mirror elements 3 are parallel to each other and substantially in the transmissive surface 12c, and hence the XY plane. Parallel.

  The illumination device 2 includes a spatial light modulator 13 and a modulation control unit 31 that controls the operation of the drive unit 4 of the spatial light modulator 13. The main control system 30 supplies the modulation control unit 31 with information on illumination conditions (light quantity distribution on an illumination pupil plane 22P described later) and the emission timing of the illumination light IL. The modulation control unit 31 normally drives the drive unit so that the inclination angles around the two axes of the many mirror elements 3 are maintained at values corresponding to the illumination conditions during the period in which the illumination light IL is emitted in pulses. 4 is controlled.

  In this case, the illumination light IL is incident on the incident surface 12d of the prism 12 in parallel with the optical axis AXI. The incident illumination light IL is totally reflected by the first reflection surface 12 a, then passes through the transmission surface 12 c and enters the multiple mirror elements 3 of the spatial light modulator 13. Then, the illumination light IL that is reflected by the multiple mirror elements 3 and divided into wavefronts is incident on the transmission surface 12c again, and then totally reflected by the second reflection surface 12b and emitted from the emission surface 12e. Accordingly, the angle of the first reflecting surface 12a with respect to the incident surface 12d is such that the light beam incident perpendicularly to the incident surface 12d is totally reflected by the first reflecting surface 12a and the light beam totally reflected by the first reflecting surface 12a is the transmitting surface. It may be in a range that transmits 12c. At this time, if the reflection surface of a certain mirror element 3 is substantially parallel to the transmission surface 12c, the illumination light IL reflected by the mirror element 3 is transmitted through the transmission surface 12c and completely reflected by the second reflection surface 12b. After being reflected, the light passes through the emission surface 12e and is emitted substantially parallel to the optical axis AXI. Therefore, by controlling the inclination angle of each mirror element 3 around the two axes, the two directions orthogonal to the optical axis AXI of the illumination light IL reflected from the mirror element 3 and emitted from the prism 12 (the θx direction and The angle in the θz direction) can be controlled. Controlling the angle (direction of the optical path) of the illumination light IL with respect to the optical axis AXI in this way is spatial modulation by each mirror element 3 of the present embodiment.

Although the reflection surfaces 12a and 12b of the prism 12 use total reflection, a reflection film may be formed on the reflection surfaces 12a and 12b, and the illumination light IL may be reflected by the reflection film.
The illumination light IL emitted from the prism 12 is incident on the incident surface 22I of the fly-eye lens 15 (optical integrator) via the relay optical system 14 (intensity distribution forming optical system) having a predetermined focal length.

  FIG. 3D shows the incident surface 22I of the fly-eye lens 15. In FIG. 3D, the fly-eye lens 15 has a number of biconvex lens elements having a rectangular cross-sectional shape having a width a in the Z direction (a direction corresponding to the Y direction on the reticle surface) and a length b in the X direction. 15a is disposed so as to be in close contact with each other in the Z direction and the X direction. The entrance surface 22I is optically substantially conjugate with the reticle surface. Therefore, the cross-sectional shape of the lens element 15a is substantially similar to the illumination area 36 on the reticle surface, and the ratio of the width a to the length b is, for example, about 1: 3. As an example, the width a is about 1 to 2 mm, and the number of arrangement of the lens elements 15a in the Z direction is about several tens.

  Here, a configuration example of the spatial light modulator 13 will be described. FIG. 2 is an enlarged perspective view showing a part of the spatial light modulator 13. In FIG. 2, the spatial light modulator 13 individually controls a number of mirror elements 3 arranged so as to be in close contact with each other at a constant pitch in the X direction and the Y direction, and angles of reflection surfaces of the many mirror elements 3. The drive part 4 to be included. The number of arrangement of the mirror elements 3 in the X direction and the Y direction is, for example, several hundred. As an example, the drive mechanism (drive unit 4) of the mirror element 3 includes a hinge member (not shown) that supports the mirror element 3, and a plurality of electrodes (not shown) for swinging and tilting the hinge member by electrostatic force. ). A more detailed configuration of the spatial light modulator 13 is disclosed in, for example, Japanese Patent Application Laid-Open No. 2002-353105.

  Note that any other mechanism can be used as the drive mechanism of the mirror element 3. Furthermore, although the mirror element 3 is a substantially square plane mirror, the shape thereof may be an arbitrary shape such as a rectangle. However, from the viewpoint of light utilization efficiency, a shape that can be arranged without a gap is preferable. Moreover, it is preferable that the interval between the adjacent mirror elements 3 is minimized. In addition, at present, the shape of the mirror element 3 is, for example, about 10 μm square to several tens of μm square, but it is preferable that the mirror element 3 is as small as possible in order to allow fine changes in illumination conditions. Furthermore, a concave or convex mirror element (not shown) can be used as the mirror element 3 instead of a plane mirror.

As the spatial light modulator 13, for example, Japanese Patent Publication No. 10-503300 and European Patent Publication No. 779530 corresponding thereto, Japanese Patent Application Laid-Open No. 2004-78136, and US Patent No. 1 corresponding thereto. 6,900,915 specification, special table 2006-52434
The spatial light modulator disclosed in US Pat. No. 9 and US Pat. No. 7,095,546 corresponding thereto can be used.

  3A and 3C show optical systems from the prism 12 to the fly-eye lens 15 in FIG. 3A and 3C, the multiple mirror elements 3 of the spatial light modulator 13 are typically represented by a plurality of mirror elements 3A to 3G. 3A, in the present embodiment, the reflecting surfaces of the mirror elements 3A to 3G of the spatial light modulator 13 are disposed substantially on the front focal plane of the relay optical system 14, and the relay optical system 14 having a focal length f is disposed. The incident surface 22I of the fly-eye lens 15 is disposed at a position defocused in the + Y direction by a predetermined distance from the rear focal plane FP. Therefore, the distance e between the principal point of the relay optical system 14 and the incident surface 22I is larger than the focal length f.

  In this case, the inclination angle of the light beam incident on the relay optical system 14 along the plane including the optical axis AXI and parallel to the ZY plane in the θx direction with respect to the optical axis AXI is θ, and the light beam on the main plane of the relay optical system 14 Assuming that the height from the optical axis AXI is H, the height h (position in the Z direction) from the optical axis AXI at the position where the light beam is collected on the incident surface 22I of the fly-eye lens 15 is approximately as follows. Can be calculated.

h = f · tan θ− (e−f) · H / f (1)
In Expression (1), the inclination angle θ is a value calculated according to the inclination angle (value set by the modulation control unit 31) in the θx direction of the reflection surfaces of the mirror elements 3A to 3G, and the height H Is calculated from the known position in the Y direction and the tilt angle θ of each mirror element 3A-3G. Similarly, the tilt angle in the θz direction and the position in the X direction of the light beam incident on the relay optical system 14 can be determined from the tilt angle in the θy direction and the known X direction position of the reflecting surfaces of the mirror elements 3A to 3G. Based on the tilt angle and position, the position in the X direction on the incident surface 22I of the fly-eye lens 15 of the light beam emitted from the relay optical system 14 can be calculated from the same calculation formula as Expression (1).

  In this case, when the illumination light IL is incident on a predetermined lens element 15a of the fly-eye lens 15, the pupil plane of the illumination optical system ILS (hereinafter referred to as “the vicinity of the exit surface”) having a rear focal plane (surface near the exit surface) of the lens element 15a. A light source (secondary light source) by the lens element 15a is formed on 22P (referred to as an illumination pupil plane). In other words, the light amount distribution of the illumination light IL on the entrance surface 22I of the fly-eye lens 15 is substantially the same as the light amount distribution on the illumination pupil plane 22P on the exit surface side of the fly-eye lens 15. Therefore, by individually controlling the tilt angles around the two axes of all the mirror elements 3A to 3G of the spatial light modulator 13, the light quantity distribution (the shape of the secondary light source) of the illumination light IL on the illumination pupil plane 22P is obtained. It can be controlled to an arbitrary distribution. In practice, the main control system 30 supplies the modulation control unit 31 with information on the target light amount distribution on the illumination pupil plane 22P (and thus the incident plane 22I). The modulation control unit 31 obtains the target values of the inclination angles in the θx direction and θy direction of the reflection surfaces of the mirror elements 3A to 3G from Equation (1) and the like so that the target light quantity distribution can be obtained on the incident surface 22I. These inclination angles are calculated and set in the drive unit 4 of the spatial light modulator 13.

  In the present embodiment, when the power of the spatial light modulator 13 (drive unit 4) is off, the reflecting surfaces of all the mirror elements 3A to 3G are almost in the XY plane as shown in FIG. The illumination light IL that is parallel and reflected by the mirror elements 3A to 3G enters the relay optical system 14 substantially parallel to the optical axis AXI. Then, the illumination light IL emitted from the relay optical system 14 is once condensed on the rear focal plane FP, and then a substantially circular region having a diameter d of the entrance surface 22I of the fly-eye lens 15 shown in FIG. Incident on 25F. In the present embodiment, as will be described later, the illumination light IL is not collected in a region having a smaller area than the region 25F on the incident surface 22I. Therefore, the region 25F is hereinafter referred to as a minimum region 25F. In addition, the minimum region 25F is predicted to have no possibility of damaging the lens elements 15a of the fly-eye lens 15 experimentally, for example, when the illumination light IL with normal power is irradiated for a normal irradiation time. This is the smallest area. Note that the minimum region 25F may be a substantially square region having a width d on one side.

Further, when the optically minimum region where the illumination light IL from the relay optical system 14 is collected on the incident surface 22I is defined as a region having a diameter φ, this region having a diameter φ is defined as a single region on the incident surface 22I. Can be considered. When the wavelength of the illumination light IL is λ and the numerical aperture of the relay optical system 14 is NAR, the diameter φ is approximately as follows.
φ = λ / NAR (2)
As an example, if the numerical aperture NAR is 0.1, the wavelength λ is 193 nm, so the diameter φ (the diameter of a single point region) is approximately 2 μm.

  In the present embodiment, the incident surface 22I is defocused from the rear focal plane FP of the relay optical system 14. Therefore, in the minimum area 25F where the illumination light IL is collected on the incident surface 22I, when a light beam parallel to the relay optical system 14 is incident, the light beam is condensed on the incident surface 22I by the relay optical system 14. The area is the same size as the area to be processed. In this case, the minimum area 25F is larger than the minimum area (area having a diameter φ) that can be optically condensed by the relay optical system 14.

  As an example, the diameter d of the minimum region 25F is set to a width a in the short side direction of the lens element 15a of the fly-eye lens 15 or larger than this, and the value of the diameter d is stored in the storage unit of the modulation control unit 31. . The width a is, for example, 1 to 2 mm, and the diameter φ of the formula (2) is, for example, about 2 μm. Therefore, the diameter d of the minimum region 25F is sufficiently larger than the diameter φ of one point region. Thus, even if the illumination light IL is irradiated from the light source 7 when the power of the spatial light modulator 13 (drive unit 4) is off, the illumination light IL is short on the at least one lens element 15a of the fly-eye lens 15. Irradiation is performed across the two lens elements 15a in the entire direction or in the short side direction, so that the optical material and antireflection film of the lens element 15a are not damaged.

In this case, illuminating light incident on the relay optical system 14 is D, where D is the diameter of the largest circular area 26 (illuminating area when the coherence factor (σ value) is 1) centered on the optical axis AXI within the incident surface 22I. Assuming that the cross-sectional shape of IL is substantially the same as that of the circular region 26, the following relationship is established.
f: (e−f) = D: d (3) Therefore, e = (1 + d / D) f (4)
Therefore, as an example, if d = 2a and D = 50a, the distance e is (52/50) f. In this case, the diameter d of the minimum region 25F is twice the width a of the lens element 15a. When the power of the spatial light modulator 13 is off, the illumination light IL is at least two lens elements 15a of the fly-eye lens 15. The risk of damage to the lens element 15a is further reduced.

  In practice, even if the minimum area 25F is within one lens element 15a, the optical element of the lens element 15a is sufficient if the diameter d of the minimum area 25F is at least about 1/100 times the diameter D of the circular area 26. The possibility that the material, the antireflection film and the like are damaged is low. Accordingly, the diameter d may be approximately 1/100 or more of the diameter D. At this time, from the formula (4), it is preferable that the distance e between the relay optical system 14 and the entrance surface 22I of the fly-eye lens 15 satisfies the following condition. The maximum value of the distance e is preferably (52/50) f described above, for example.

e ≧ (101/100) f (5)
In the example of FIG. 3A, the reflected light from the mirror elements 3E to 3G and 3A to 3D is applied to the two illumination regions 25A and 25B separated in the Z direction of the incident surface 22I of the fly-eye lens 15, respectively. Yes. The number of mirror elements 3 that reflect light incident on the illumination areas 25A and 25B is substantially equal to each other. Then, on the illumination pupil plane 22P, as shown in FIG. 3B, a secondary light source (substantial surface light source) having substantially the same intensity distribution as the illumination areas 25A and 25B at the same position as the illumination areas 25A and 25B. 24A and 24B are formed.

  For example, on the pattern surface (reticle surface) of the reticle R in FIG. 1, a line and space pattern (hereinafter referred to as an L & S pattern) arranged at a pitch close to the resolution limit in the Y direction (or X direction) is mainly used. In the case of exposure, the secondary light source on the illumination pupil plane 22P is a secondary secondary light source 24A, 24B in the Z direction in FIG. 3B (or a secondary secondary light source in the X direction in FIG. 4A). 24C, 24D). Similarly, the spatial light modulator 13 converts the secondary light source on the illumination pupil plane 22P into a circular secondary light source 28A for normal illumination in FIG. 4B and a secondary light source for annular illumination in FIG. 4C. The secondary light source 28B and the quadrupole secondary light sources 24E to 24H for quadrupole illumination shown in FIG. Further, the spatial light modulator 13 can change the interval between the secondary light sources 24A and 24B and / or the individual sizes of the secondary light sources 24A and 24B to arbitrary values in FIG. 3B, for example. It is.

  Next, in FIG. 1, the illumination light IL from the secondary light source formed on the illumination pupil plane 22P includes a first relay lens 16, a reticle blind (field stop) 17, a second relay lens 18, and an optical path bending mirror. 19 and the condenser optical system 20 are used to illuminate the illumination area 36 on the reticle surface so as to obtain a uniform illuminance distribution. The illumination optical system ILS includes the optical members from the beam expander 8 to the condenser optical system 20. Each optical member including the spatial light modulator 13 of the illumination optical system ILS is supported by a frame (not shown).

The pattern in the illumination area 36 of the reticle R is an exposure area 37 on one shot area of the wafer W coated with a resist (photosensitive material) via a telecentric projection optical system PL on both sides (or one side on the wafer side). Are projected at a predetermined projection magnification (for example, 1/4, 1/5, etc.).
The reticle R is attracted and held on the upper surface of the reticle stage RST, and the reticle stage RST is movable on the upper surface of the reticle base (not shown) at a constant speed in the Y direction and at least in the X direction, the Y direction, and the θz direction. It is placed so that it can move. The two-dimensional position of reticle stage RST is measured by a laser interferometer (not shown), and based on this measurement information, main control system 30 determines the position of reticle stage RST via a drive system (not shown) such as a linear motor. And control the speed.

  On the other hand, wafer W is sucked and held on the upper surface of wafer stage WST via a wafer holder (not shown), and wafer stage WST moves stepwise in the X and Y directions on the upper surface of a wafer base (not shown) and in the Y direction. Can move at a constant speed. The two-dimensional position of wafer stage WST is measured by a laser interferometer (not shown). Based on this measurement information, main control system 30 moves the position of wafer stage WST via a drive system (not shown) such as a linear motor. And control the speed. In order to align the reticle R and the wafer W, the wafer stage WST is provided with an aerial image measurement system (not shown) that measures the position of the image of the alignment mark on the reticle R, and the side surface of the projection optical system PL. Is provided with a wafer alignment system (not shown) for detecting the position of the alignment mark of the wafer W.

  When the exposure apparatus EX exposes the wafer W, the main control system 30 selects an illumination condition (the shape of the secondary light source on the illumination pupil plane 22P) according to the pattern of the reticle R, and modulates the selected illumination condition. Set to 31. In response to this, the modulation control unit 31 individually controls the inclination angle of each mirror element 3 of the spatial light modulator 13 to set the shape of the secondary light source on the illumination pupil plane 22P. Subsequently, the wafer W is moved to the scanning start position by the step movement of the wafer stage WST. Thereafter, pulse light emission of the light source 7 is started, and the wafer W is exposed to the exposure region 37 via the wafer stage WST in synchronization with the movement of the reticle R in the Y direction with respect to the illumination region 36 via the reticle stage RST. The one shot area of the wafer W is scanned and exposed by moving the projection magnification as a speed ratio in the corresponding direction. In this way, the image of the pattern of the reticle R is exposed to all shot regions on the wafer W by the step-and-scan operation that repeats the step movement of the wafer W and the scanning exposure.

  At the time of exposure by the exposure apparatus EX, the illumination light IL from all the mirror elements 3 of the spatial light modulator 13 is on the incident surface 22I of the fly-eye lens 15 more than the minimum region 25F having the diameter d in FIG. If the light is condensed in a narrow area having a small area, the lens element 15a may be damaged. Hereinafter, an example of an exposure operation for preventing the illumination light IL from the spatial light modulator 13 from being condensed in a region smaller than the minimum region 25F will be described with reference to the flowchart of FIG. This operation is controlled by the main control system 30.

  First, in step 102 of FIG. 6, the light emission of the light source 7 of the exposure apparatus EX is stopped, and the power of the spatial light modulator 13 is turned off. In this state, in step 104, reticle R is loaded onto reticle stage RST. In step 106, the illumination condition of the reticle R, that is, information on the light quantity distribution on the illumination pupil plane 22 </ b> P is supplied from the main control system 30 to the modulation control unit 31. The modulation control unit 31 calculates inclination angles in the θx direction and θy direction of each mirror element 3 of the spatial light modulator 13 in order to obtain the light amount distribution. In the next step 108, the modulation control unit 31 switches the relay optical system 14 from the spatial light modulator 13 when the tilt angle of each mirror element 3 of the spatial light modulator 13 is the tilt angle calculated in step 106. It is confirmed whether the area of the illumination area of the illumination light IL incident on the incident surface 22I of the fly-eye lens 15 is smaller than the area of the minimum area 25F.

  When the area of the illumination area of the illumination light IL on the incident surface 22I is smaller than the minimum area 25F, the operation proceeds to step 110, and the modulation control unit 31 sends alarm information to the main control system 30. When the illumination area of the illumination light IL on the incident surface 22I is smaller than the minimum area 25F in this way, for example, the illumination condition is so-called small as shown in FIGS. For σ illumination, this may occur when the secondary light source on the illumination pupil plane 22P, and hence the illumination area 25H on the entrance surface 22I of the fly-eye lens 15, is a small circular area centered on the optical axis AXI.

  In response to the alarm information, the main control system 30 issues an alarm to the operator. In response to this, the operator executes a countermeasure such as slightly changing the illumination condition as an example. As a result, as shown in FIG. 5A, the illumination light IL is reliably prevented from being condensed on the illumination area 25H narrower than the minimum area 25F on the incident surface 22I of the fly-eye lens 15, and the fly-eye lens 15 damage can be prevented. Similarly, at the time of switching illumination conditions, for example, as shown in FIGS. 5C and 5D, a narrow illumination region 25H located at a position other than the optical axis AXI on the incident surface 22I of the fly-eye lens 15 is formed. It is also possible to reliably prevent the illumination light IL from being collected.

  On the other hand, when the area of the illumination area of the illumination light IL on the incident surface 22I is equal to or larger than the area of the minimum area 25F in step 108, the operation proceeds to step 112, and the modulation control unit 31 performs the spatial light modulator 13. And the tilt angle of each mirror element 3 is set to the value calculated in step 106 via the drive unit 4. In the next step 114, the main control system 30 causes the light source 7 to emit pulses, and aligns the reticle R using an aerial image measurement system (not shown).

  Thereafter, in step 116, wafer W coated with a resist is loaded onto wafer stage WST, and alignment of wafer W is performed. Subsequently, in step 118, an image of the pattern of the reticle R is exposed to each shot area of the wafer W by a step-and-scan method. Thereafter, in step 120, the exposed wafer W is unloaded. In the next step 122, if there is an unexposed wafer, the operation returns to step 116, and the next wafer is exposed.

The effects and the like of this embodiment are as follows.
(1) The illumination device 2 provided in the exposure apparatus EX of FIG. 1 of the present embodiment has an illumination optical system ILS that illuminates the reticle surface (irradiated surface) using the illumination light IL from the light source 7. The illumination device 2 (illumination optical device) drives each of the plurality of mirror elements 3 (optical elements) and the plurality of mirror elements 3 arranged two-dimensionally with respect to the optical path of the illumination light IL. And a relay optical that guides the illumination light IL deflected by each of the plurality of mirror elements 3 to the incident surface 22I (predetermined surface) of the fly-eye lens 15. The relay optical system 14 receives the illumination light IL via the plurality of mirror elements 3 when the deflection directions of the illumination light IL in the plurality of mirror elements 3 are aligned in the same direction. Condensing light is prevented from being focused on a region having a smaller area than the minimum region 25F on the incident surface 22I, and in other words, a single point region that is the smallest region that can be condensed by the relay optical system 14.

  The exposure operation of the present embodiment is arranged in the illumination optical system ILS that illuminates the reticle surface using the illumination light IL from the light source 7, and is two-dimensionally arranged on the optical path of the illumination light IL, This includes a method for controlling the spatial light modulator 13 having a plurality of mirror elements 3 (optical elements) that are driven to individually control the deflection direction of the illumination light IL. In this control method, the illumination light IL from the plurality of mirror elements 3 is guided to the incident surface 22I (predetermined surface) of the fly-eye lens 15 via the relay optical system 14 (step 112), and the plurality of mirror elements 3 are incident. Control is performed so that the illumination light IL on the surface 22I is not condensed in a region having a smaller area than the minimum region 25F, and in other words, a single region that is the smallest region that can be condensed by the relay optical system 14 (step 106). 108, 110).

  According to the present embodiment, the illumination light IL is irradiated when the reflecting surfaces of all the mirror elements 3 are substantially parallel by, for example, a reset operation of the spatial light modulator 13 having the plurality of mirror elements 3 and the drive unit 4. However, the substantially parallel light from all the mirror elements 3 is collected in a region smaller than the minimum region 25F (minimum region in which the lens element is hardly damaged) on the incident surface 22I of the fly-eye lens 15. do not do. Therefore, the optical material and antireflection film of each lens element 15a of the fly-eye lens 15 are not damaged. Therefore, even during normal use, the illumination light IL is less likely to be collected in a narrow area on the incident surface 22I, the maintenance interval of the fly-eye lens 15 can be increased, and the maintenance cost of the illumination device 2 can be reduced.

Note that the illumination light IL from the plurality of mirror elements 3 may be allowed to be condensed on a region of the incident surface 22I that is smaller than the minimum region 25F and has a larger area than one point. Also in this case, the possibility that the fly-eye lens 15 is damaged is reduced.
(2) In the present embodiment, the incident surface 22I of the fly-eye lens 15 disposed after the plurality of mirror elements 3 is a predetermined surface that prevents the illumination light IL from being collected in a single point region. The one point region is smaller than the minimum region 25F, and the minimum region 25F is a circular region having the same width as the width a in the short side direction of the cross-sectional shape of each lens element 15a of the fly-eye lens 15. Therefore, the one point area is a circular area having a diameter smaller than the width a. In this case, the risk of damage to the lens element 15a is further reduced.

The predetermined surface may be the surface of an optical member other than the fly-eye lens 15.
(3) Further, the spatial light modulator 13 of the present embodiment includes a plurality of mirror elements 3 (reflection elements) as optical elements. Thus, when the mirror element 3 is used, the utilization efficiency of the illumination light IL is high.
(4) In the spatial light modulator 13 (driving unit 4), the reflecting surfaces of all the mirror elements 3 are parallel to each other along substantially the same surface when the power is off. Furthermore, since the incident surface 22I of the fly-eye lens 15 is defocused from the rear focal plane FP of the relay optical system 14, even when the illumination light IL is applied to the spatial light modulator 13 whose power is off, the incident surface 22I. Then, since the illumination light IL spreads (because it is not condensed at one point), there is no possibility that the fly-eye lens 15 is damaged.

  (5) Also, during multipole illumination (for example, during dipole illumination), the relay optical system 14 is in a power-on state (first state) in which the drive unit 4 can drive the plurality of mirror elements 3. The illumination light IL is guided through the plurality of mirror elements 3 to the plurality of regions 25A and 25B of the incident surface 22I, and the power-off state in which the drive unit 4 cannot drive the plurality of mirror elements 3 (second state) ), The illumination light IL that has passed through the plurality of mirror elements 3 is prevented from being condensed at one point on the incident surface 2I. Therefore, even if the illumination light IL is irradiated to the plurality of mirror elements 3 with the power of the driving unit 4 turned off, the fly-eye lens 15 is not damaged.

  In the spatial light modulator 13, the reflecting surfaces of all the mirror elements 3 do not necessarily have to be parallel when the drive unit 4 is powered off. In this case, the entrance surface 22I of the fly-eye lens 15 is disposed at or near the rear focal plane FP of the relay optical system 14, and the drive unit 4 always makes the tilt angles of all the mirror elements 3 incident. You may control so that illumination light IL may not be irradiated to the area | region (1 area | region) narrower than the minimum area | region 25F by the surface 22I.

(6) In addition, the relay optical system 14 is based on at least one of the intensity distribution of the illumination light IL formed on the incident surface 22I and the shape of the illumination light IL when the power is on (first state). The intensity of the illumination light IL condensed on the incident surface 22I when the power is off (second state) may be attenuated (the irradiation area may be widened).
This means that depending on the arrangement of the relay optical system 14, the shape of the illumination light IL on the incident surface 22I (and thus the illumination pupil plane 22P) during modified illumination may be somewhat blurred.

  (7) The exposure apparatus EX of the present embodiment is an exposure apparatus that exposes the pattern of the reticle R onto the wafer W (substrate), and includes an illumination optical system ILS for illuminating the pattern of the reticle R. 2 and a projection optical system PL that forms an image of the pattern on the surface of the wafer W. According to this exposure apparatus EX, it is possible to reduce the maintenance cost of the illuminating device 2, and consequently the exposure apparatus EX.

Next, in the above embodiment, the following modifications are possible.
(1) In the above embodiment, in the illumination device 2 (illumination optical system ILS), the prism 12 is used to supply the illumination light IL to the spatial light modulator 13, and therefore the illumination optical system ILS is arranged. Easy. Instead of the internal reflection type prism 12, as shown in the modified example of FIG. 7A, a mirror member 42 having reflective surfaces 42a and 42b inclined with respect to each other may be used. In the above embodiment, as shown in FIG. 3C, the entrance surface 22I of the fly-eye lens 15 is defocused outward with respect to the rear focal plane FP of the relay optical system 14. .

  On the other hand, as shown in FIG. 7A, the incident surface 22I of the fly-eye lens 15 may be disposed at a position defocused inward with respect to the rear focal plane FP of the relay optical system 14. In this configuration, the distance e1 from the main plane of the relay optical system 14 to the incident surface 22I is shorter than the focal length f. Further, for example, when the power source of the driving unit 4 of the spatial light modulator 13 is off and the reflecting surfaces of all the mirror elements 3A to 3G are parallel, the illumination light IL reflected in parallel from the mirror elements 3A to 3G is incident. The distance e1 may be set so that the illumination area on the surface 22I is the minimum area 25F having the same size as the example of FIG.

  In this case, as shown in FIG. 7B, each lens element 15a in the minimum region 25F of the fly-eye lens 15 forms a secondary light source 43 on the illumination pupil plane 22P, so that the fly-eye lens 15 exits. For example, the illumination light IL is not condensed on the surface of one lens element 15a. Accordingly, the exit surface of the fly-eye lens 15 may be positioned close to the rear focal plane FP of the relay optical system 14.

  (2) In the above embodiment, the fly-eye lens 15 is used as an optical integrator, but a microlens array (micro fly-eye lens) may be used as an optical integrator. As an example, a microlens array for a scanning exposure apparatus is formed by forming a large number of biconvex microlenses having a cross-sectional shape of approximately 0.6 mm × 0.2 mm in vertical and horizontal directions, and the short side direction of the microlens. The number of microlenses arranged in is about several hundreds. In this case, the width of the minimum area of the illumination light irradiated from the spatial light modulator 13 onto the incident surface of the microlens array may be, for example, several times to 20 times the width in the short side direction of the microlens.

  (3) Instead of the fly-eye lens 15 which is the wavefront division type integrator of FIG. 1, a rod type integrator as an internal reflection type optical integrator may be used. In this case, for example, the arrangement of the optical system and the control of the tilt angle of each mirror element 3 of the spatial light modulator 13 so that the illumination light IL is not collected in a predetermined narrow area on the entrance surface of the rod integrator. Can be done.

  Further, when an electronic device (microdevice) such as a semiconductor device is manufactured using the exposure apparatus according to the above-described embodiment, the electronic device has a function / performance design step 221 as shown in FIG. Step 222 for producing a mask (reticle) based on this design step, Step 223 for producing a substrate (wafer) as a base material of the device, and a step of exposing the mask pattern onto the substrate by the exposure apparatus EX of the above-described embodiment. Developing the exposed substrate, substrate processing step 224 including heating (curing) and etching step of the developed substrate, device assembly step (including processing processes such as dicing process, bonding process, and packaging process) 225, and It is manufactured through an inspection step 226 and the like.

In other words, the above-described device manufacturing method uses an exposure apparatus EX to expose a substrate (wafer W) through a mask pattern, develop the substrate, and mask corresponding to the mask pattern. A development step for forming a layer on the surface of the substrate, and a processing step for processing (heating, etching, etc.) the surface of the substrate through the mask layer.
According to this device manufacturing method, the maintenance cost of the exposure apparatus can be reduced, so that the electronic device can be manufactured at low cost with high accuracy.

The present invention can also be applied to an immersion type exposure apparatus disclosed in, for example, US Patent Application Publication No. 2007/242247 or European Patent Application Publication No. 1420298. Furthermore, the present invention can also be applied to a proximity type exposure apparatus that does not use a projection optical system, and an illumination apparatus (illumination optical apparatus) of the exposure apparatus.
Further, the present invention is not limited to the application to the manufacturing process of a semiconductor device. For example, a manufacturing process such as a liquid crystal display element and a plasma display, an imaging element (CMOS type, CCD, etc.), a micromachine, a MEMS ( (Microelectromechanical systems), thin film magnetic heads, and various devices (electronic devices) such as DNA chips can be widely applied. As described above, the present invention is not limited to the above-described embodiment, and various configurations can be taken without departing from the gist of the present invention.

  EX ... exposure device, ILS ... illumination optical system, R ... reticle, PL ... projection optical system, W ... wafer, 2 ... illumination device, 3 ... mirror element, 4 ... drive unit, 12 ... prism, 13 ... spatial light modulator , 14 ... Relay optical system, 15 ... Fly eye lens, 30 ... Main control system, 31 ... Modulation control unit

Claims (13)

In an illumination optical device that illuminates an illuminated surface using light from a light source,
A plurality of optical elements arranged two-dimensionally with respect to the optical path of the light;
A driving mechanism for driving each of the plurality of optical elements and individually controlling the deflection direction of the light;
An optical system for guiding the light deflected by each of the plurality of optical elements to a region within a predetermined plane,
The optical system prevents the light from passing through the plurality of optical elements from being condensed at one point on the predetermined surface when the light deflection directions of the plurality of optical elements are aligned in the same direction. An illumination optical device.   2. The drive mechanism drives the plurality of optical elements so that the light deflected by each of the plurality of optical elements is not condensed at one point on the predetermined surface. Illumination optical device. A fly-eye lens having a plurality of lens elements disposed between the optical system and the irradiated surface;
The predetermined surface is an incident surface of the fly-eye lens,
3. The illumination optical apparatus according to claim 1, wherein the one-point region on the predetermined surface is a region having a width equal to or smaller than a cross-sectional shape of each lens element.   The illumination optical apparatus according to claim 1, further comprising a condenser optical system that guides light from the fly-eye lens to the irradiated surface.   5. The illumination optical apparatus according to claim 1, wherein the plurality of optical elements include a mirror element capable of controlling an inclination angle at which light from the light source is reflected.   6. The illumination optical device according to claim 5, wherein the drive mechanism is powered off, and the tilt angles of the plurality of mirror elements are the same.   The optical system guides the light through the plurality of optical elements to a plurality of regions in the predetermined plane when in a first state in which the plurality of optical elements can be driven by the driving mechanism, and In the second state in which the plurality of optical elements cannot be driven by the driving mechanism, the light passing through the plurality of optical elements is prevented from being collected at one point on the predetermined surface. The illumination optical apparatus according to any one of claims 1 to 5.   The optical system focuses on the predetermined surface in the second state based on at least one of the light intensity distribution and the light shape formed on the predetermined surface in the first state. The illumination optical apparatus according to claim 7, wherein the intensity of the light is attenuated. A method of controlling a spatial light modulator having a plurality of optical elements that are two-dimensionally arranged with respect to an optical path of light that illuminates a surface to be illuminated and that are individually driven to control the deflection direction of the light. ,
Directing the light from the plurality of optical elements to a predetermined surface via an optical system;
A control method comprising: controlling the plurality of optical elements of the spatial light modulator so that the light is not condensed at one point on the predetermined surface. The predetermined surface is an entrance surface of a fly-eye lens having a plurality of lens elements;
10. The control method according to claim 9, wherein the one-point region on the predetermined surface is a region having a width equal to or smaller than a cross-sectional shape of each lens element. 11.   An exposure apparatus comprising the illumination optical apparatus according to claim 1, wherein the substrate is exposed with light from the illumination optical apparatus through a predetermined pattern.   The exposure apparatus according to claim 11, further comprising a projection optical system that forms an image of the predetermined pattern on the substrate. An exposure step of exposing the substrate through the predetermined pattern using the exposure apparatus according to claim 11 or 12,
A development step of developing the substrate and forming a mask layer corresponding to the predetermined pattern on the surface of the substrate;
A processing step of processing the surface of the substrate through the mask layer;
A device manufacturing method including:

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