JPH11251233A - Projection aligner and method and device for alignment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projection aligner and method and device for alignment, wherein a first member (mask) allocated in an object surface side of a projection optical system and a second member (sensitized substrate) allocated on an image surface side of a system are aligned with each other with high accuracy and throughput. SOLUTION: A projection exposure device 30 comprises an alignment (matching) device for optical alignment between a reticle 11 allocated in an object surface side of a projection optical system 13 and a wafer 14 allocated in an image surface side of a system. The device comprises a first illuminating system 1, which projects an exposing illumination light as a first illuminating light AL1 to a reticle matching mark RM allocated in a reticle side, a second illuminating system which projects a second illuminating light AL2 wider than the first illuminating light in wavelength width to a wafer matching mark WM allocated in the wafer 14 side, and a detection device which photodetects the light produced at the reticle matching mark and the wafer matching mark, respectively, to output a signal corresponding to the relative positional relationship between the reticle matching mark RM and the wafer matching mark WM.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a projection exposure apparatus, an alignment apparatus, and an alignment method, and more particularly, to a first member (for example, a mask) disposed on the object plane side of a projection optical system, and a projection optical system. The present invention relates to a projection exposure apparatus, an alignment apparatus, and an alignment method capable of optically aligning a second member (for example, a photosensitive substrate) disposed on the image plane side with high optical precision and high throughput.

[0002]

2. Description of the Related Art In manufacturing a semiconductor device or a liquid crystal display device, for transferring a pattern drawn on an original plate such as a mask or a reticle onto a photosensitive substrate such as a semiconductor wafer or a transparent substrate coated with a resist. And a projection exposure apparatus.

In general, in the manufacture of a semiconductor device, several to dozens of circuit patterns are laminated via an insulating layer.
It is necessary to accurately overlap a circuit pattern already formed on the wafer with a circuit pattern or a contact hole pattern to be exposed next. For this purpose, the projection exposure apparatus is provided with an alignment device.

FIG. 5 shows an example of a conventional projection exposure apparatus with an alignment device. As shown in FIG. 5, the image of the reticle 11 is projected and exposed on the wafer 14 by the projection optical system 13. The wafer W is mounted on a wafer stage 28 that can move in an XY plane substantially parallel to the image plane of the projection optical system 13. The position of the wafer stage 28 is managed by the interferometers 22X and 22Y.

Above the wafer stage 28, an off-axis type wafer alignment sensor 42 is fixed to the projection optical system 13, and a wafer alignment mark formed on the wafer 14 is provided. The position of the reference mark 41 formed on the reference pattern plate 40 mounted on the WM or the wafer stage 28 can be measured. Although not shown, an index serving as a reference when measuring an alignment mark is provided inside the wafer alignment sensor 42.

On the reticle 11, a TTR (Through Th
e Reticle) type reticle alignment sensor 4
Rectilinear alignment marks RMA and RMB that can be observed by 3A and 43B are formed. These and the reticle alignment index F on the wafer stage 28
By observing MA and FMB simultaneously, reticle alignment marks RMA and RMB of reticle R and reticle alignment index F on wafer stage 28 are obtained.
Positioning with MA and FMB can be performed.

The reticle alignment index FM formed on the reference pattern plate 40 on the wafer stage 28
The distance between A, FMB and the reference mark 41 for the wafer alignment sensor is accurately measured in advance.

In the apparatus having such a conventional configuration, the overlay exposure is performed in the order of baseline measurement, wafer alignment measurement, and exposure. Next, the procedure will be described.

First, the measurement of the baseline will be described. This baseline is the reticle alignment
The distance from the position of the reticle 11 represented by the marks RMA and RMB to the index inside the wafer alignment sensor 42. This measurement is performed as follows. That is, the reticle alignment sensor 43
At A and 43B, the relative displacement L1 from the reticle alignment marks RMA and RMB to the reticle alignment indexes FMA and FMB, respectively, is measured. At the same time, the reference mark 41 on the wafer stage 28 is
The distance L2 to the index inside the sensor 42 is measured. Then, a base line is obtained by calculating using the relative displacement L1 and the distance L2.

Next, in a wafer alignment measurement process, an alignment alignment formed in advance on the wafer 14 is performed.
Select some of the marks WM, wafer stage 2
8 are driven, and their positions are aligned and measured by the off-axis type wafer alignment sensor 42. In this way, the shot arrangement formed on the wafer 14 can be obtained.

Finally, the wafer stage is set so that the pattern area of the reticle 11 and the shot area on the wafer 14 are accurately superimposed on the basis of the measurement result of the baseline and the measurement result of the wafer alignment. 2
8 is driven to expose.

The reticle alignment marks RMA and RMB on the reticle 11 and the alignment marks WM on the wafer 14 are directly positioned by using reticle alignment sensors 43A and 43B of the TTR (Through The Reticle) method. The reason for not matching is as follows. That is, the projection optical system 13 is designed such that aberration is minimized with respect to exposure illumination light such as a coherent laser beam or monochromatic light such as a g-line or an i-line of a mercury lamp. However, if the same light as the exposure illumination light is used as the alignment illumination light, it cannot be used because the resist on the wafer is exposed. If light different from the illumination light for exposure is used as illumination light for alignment, aberrations such as chromatic aberration in the projection optical system 13 increase, and accurate alignment becomes difficult. Therefore, the method as described above is adopted.

[0013]

In the configuration of such a conventional projection exposure apparatus, measurement of a baseline and measurement of a wafer
The alignment measurement is not simultaneous in time, and the baseline, which is the relative displacement from the reticle 11 to the wafer alignment sensor 42, may drift during this time difference. In this case, there is a problem that an overlay error occurs in the exposure result. The drift may be caused by a change in ambient temperature, a mechanical factor, or the like.

Further, in the configuration of the conventional projection exposure apparatus, since it is necessary to always perform the baseline measurement using the alignment sensor, it is inevitable that the throughput is reduced by that amount.

In the above, the problem of alignment related to the projection exposure apparatus has been described. However, other than the projection exposure apparatus, a first member disposed on the object plane side of the projection optical system via the projection optical system, When it is desired to optically align the second member disposed on the image plane side of the system,
Similar issues exist.

The present invention has been made in view of such circumstances, and has a first member (for example, a mask) disposed on the object plane side of the projection optical system and a second member disposed on the image plane side of the projection optical system.
It is an object of the present invention to provide a projection exposure apparatus, an alignment apparatus, and an alignment method capable of optically aligning a member (for example, a photosensitive substrate) with high precision and high throughput.

[0017]

In the following description, the present invention will be described with reference to the member codes shown in the drawings showing the embodiments. However, the present invention is not limited to the members shown in the drawings attached with. Further, in the present invention, the mask is used in a concept including the reticle (11).

Further, in the present invention, the projection exposure apparatus is not particularly limited, and g-line (436 nm), i-line (365 nm), KrF excimer laser (248 n
m), ArF excimer laser (193nm), F ₂ laser (157 nm), or a harmonic of a YAG laser and the like can be exemplified exposure apparatus using as an exposure light source. Further, the type of the exposure apparatus according to the type of the exposure method is not particularly limited, and a so-called step-and-repeat exposure apparatus or a so-called step-and-scan exposure apparatus may be used. A so-called step-and-scan type exposure apparatus projects a mask and a photosensitive substrate in a state where a part of a pattern on a mask such as a reticle is reduced and projected on a photosensitive substrate via a projection optical system. This is an exposure apparatus of a system in which a reduced image of a pattern on a mask is sequentially transferred to each shot area of a photosensitive substrate by synchronously moving with respect to an optical system. The exposure apparatus of this type has an advantage that the area of the pattern to be transferred can be enlarged without increasing the load on the projection optical system as compared with the exposure apparatus of the so-called step-and-repeat type.

According to a first aspect of the present invention, there is provided an exposure apparatus for transferring a pattern of a mask (11) onto a photosensitive substrate (14) via a projection optical system (13). A first illumination system (1) that irradiates a first mark (RM) arranged on one of an object plane side and an image plane side of the projection optical system (13) with first illumination light (AL1); A second mark (W) arranged on the other of the object plane side and the image plane side of the projection optical system (13)
M) a second illumination system (64) for irradiating the second illumination light (AL2) having a wider wavelength width than the first illumination light (AL1);
Light generated from each of the first mark (RM) and the second mark (WM) is received, and the first mark (R) is received.
M) and a detection device (50) that outputs a signal corresponding to the relative positional relationship between the second mark (WM) and the second mark (WM).

In this projection exposure apparatus, the first mark (R
M) and the relative positional relationship between the second mark (WM) can be directly measured, so that there is no need to perform baseline measurement, and there is no influence of the drift of the baseline. Can be maintained.

Further, since there is no need to perform baseline measurement, it contributes to an improvement in the throughput of the exposure process.

[0022] In the projection exposure apparatus according to claim 2 and 3 present invention, the first illumination system (1) is to emit illumination light of substantially the same wavelength as the exposure illumination light irradiated the a mask (11) , The detection device (5
0) preferably receives light generated from the first mark (RM) and passing through the projection optical system (13) (corresponding to claim 2).

In the exposure apparatus according to the present invention, the first
The mark (RM) is arranged on the object plane side of the projection optical system (13), and the first illumination system (1) is also used as an exposure illumination system for irradiating the exposure illumination system to the mask (11). It is preferable that this is done (corresponding to claim 3).

The projection optical system (13) is designed so as to have the smallest aberration with respect to illumination light for exposure such as coherent laser beam or monochromatic light such as g-line or i-line of a mercury lamp. is there.

[0025] In an exposure apparatus according to claim 4 the invention, the second illumination system (6
4) emits broadband light having a different wavelength from the first illumination light (AL1), and the detection device (50) is generated from the second mark (WM) without passing through the projection optical system (13). It is preferable to receive the light that emits light.
Corresponding to).

The broadband light is not particularly limited,
For example, the light has a broad wavelength distribution having a bandwidth of about 200 nm. By using such broadband light,
Unlike the case where monochromatic light is used, it is preferable because deterioration of detection accuracy caused by multiple interference of light by a resist layer or the like on the photosensitive substrate (14) can be prevented. Further, when the broadband light passes through the projection optical system (13), it is preferable that the broadband light does not pass through the projection optical system (13) because the accuracy of alignment is reduced due to the influence of aberration.

It is preferable that the broadband light has a wavelength range that does not expose the photosensitive substrate (14).

[0028] In an exposure apparatus according to claim 5 present invention, the detection device (50)
Are the first mark (RM) and the second mark (WM)
It is preferable to have an objective optical system (58) for guiding the light respectively generated from the above to the same image sensor (60) (corresponding to claim 5).

By using the same image sensor (60),
This makes it easy to output a signal corresponding to the relative positional relationship between the first mark (RM) and the second mark (WM), and contributes to the common use of parts and a reduction in the number of parts.

[0030] In an exposure apparatus according to claim 6 present invention, the detection device (50)
Is disposed on the side of the second mark (WM) with respect to the projection optical system (13), and light generated from the first mark (RM) and passing through the projection optical system (13); It is preferable to have optical members (54, 56) for making the light generated from the two marks (WM) incident on the objective optical system (58), respectively (corresponding to claim 6).

As such optical members (54, 56), for example, an optical member including a half mirror and / or a beam splitter can be exemplified.

By using such optical members (54, 56), the light generated from the first mark (RM) and the light generated from the second mark (WM) can be transmitted to the same image sensor (6).
0).

[0033] In an exposure apparatus according to claim 7 present invention, the detection device (50)
May include a light conversion element (56) for converting light generated from the first mark (RM) into light that can be detected by the imaging element (60) (corresponding to claim 7).

When the light generated from the first mark (RM) is illumination light for exposure or the like, and the light generated from the second mark (WM) is different from the illumination light, the light conversion is performed. The conversion by the element (56) facilitates detection of these lights by the same imaging element (60).

[0035] 8. The exposure apparatus according to the present invention (corresponding to claim 8), the second mark (WM) is formed on the photosensitive substrate (14), the second illumination light (AL2 It is preferable that the wavelength of ()) is different from the wavelength range in which the photosensitive substrate (14) is exposed.

The second mark (WM) is the photosensitive substrate (14)
When the photosensitive substrate (14) is formed on the photosensitive substrate (14) and the wavelength of the second illumination light (AL2) for irradiating the same is the same as the wavelength range in which the photosensitive substrate (14) is exposed.
This is because 4) may be exposed.

[0037] In an exposure apparatus according to claim 9 the invention, the first mark (R
M) is formed on the mask (11), and a signal output from the detection device (50) is preferably used for alignment between the mask (11) and the photosensitive substrate (14) (claim). Corresponds to item 9).

This is because high-precision alignment can be realized, and exposure can be performed at an accurate position.

According to the tenth and eleventh aspects of the present invention, the alignment device (50) includes a first member (11) disposed on the object plane side of the projection optical system (13);
The second member (1) disposed on the image plane side of the projection optical system (13)
4) is an alignment device for optically aligning the first member with the first member and the first member disposed on the first member (11) side.
A first illumination system (1) for irradiating a mark (RM) with first illumination light (AL1), and a first illumination light on a second mark (WM) arranged on the second member (14) side. A second illumination system (64) for irradiating a second illumination light (AL2) having a wider wavelength width than (AL1), and receiving light respectively generated from the first mark (RM) and the second mark (WM). And a detection device (50) for outputting a signal corresponding to a relative positional relationship between the first mark (RM) and the second mark (WM).

In the alignment method according to the present invention, the first member (11) disposed on the object plane side of the projection optical system (13).
And a second member (14) arranged on the image plane side of the projection optical system (13), wherein the alignment method optically aligns the second member (14) with the second member (14), which is arranged on the first member (11) side. Irradiating the first mark (RM) with the first illumination light (AL1); and providing the second mark (WM) disposed on the second member (14) side with the first illumination light (AL1). Irradiating second illumination light (AL2) having a wide wavelength width; and the first mark (RM) and the second mark (WM).
Receiving the light generated from the first mark (RM) and outputting a signal corresponding to the relative positional relationship between the first mark (RM) and the second mark (WM) (corresponding to claim 11).

According to the alignment apparatus (50) and the alignment method, the relative positional relationship between the first mark (RM) and the second mark (WM) can be directly measured, so that it is not necessary to perform baseline measurement. It is possible to stably maintain a high overlay accuracy without being affected by the drift of the baseline.

Further, since there is no need to perform baseline measurement, this contributes to an improvement in the throughput of the alignment step.

[0043]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments shown in the drawings.

FIG. 1 is a schematic diagram of a projection exposure apparatus according to one embodiment of the present invention, FIG. 2 is a schematic configuration diagram of the alignment sensor shown in FIG. 1, and FIGS. 3A and 3B are reticle alignment marks. FIG. 4 is a schematic diagram showing a relationship between the projection exposure apparatus and a wafer alignment mark. FIG.

As shown in FIG. 1 and FIG.
The exposure apparatus 30 according to the embodiment is a so-called step-and-scan exposure apparatus, in which a part of a pattern on a reticle 11 as a mask is coated with a resist as a photosensitive substrate via a projection optical system 13. Wafer 1
With the reduced projection exposure on the reticle 4, the reticle 11 and the wafer 14 are synchronously moved with respect to the projection optical system 13, so that reduced images of the pattern on the reticle 11 are sequentially transferred to each shot area of the wafer 14. It has become.

First, the overall configuration of the exposure apparatus 30 according to the present embodiment will be described with reference to FIG.

As shown in FIG. 4, the exposure apparatus 30 of the present embodiment has a KrF excimer laser (oscillation wavelength: 248 nm) as the exposure light source 1. The light source 1 for exposure is not particularly limited, and the g-line (436 nm) and the i-line (3
65 nm), ArF excimer laser (193 nm), F
_{A two-} laser (157 nm) or a pulsed light source such as a metal vapor laser light source or a harmonic generator of a YAG laser may be used.

The laser beam LB pulse-emitted from the exposure light source 1 enters the beam shaping / modulating optical system 2. In the present embodiment, the beam shaping / modulating optical system 2 includes a beam shaping optical system 2a and an energy modulator 2b. The beam shaping optical system 2a includes a cylinder lens, a beam expander, and the like, and the cross-sectional shape of the beam is shaped so as to efficiently enter the subsequent fly-eye lens 5.

The energy modulator 2b shown in FIG. 4 includes an energy coarse adjuster and an energy fine adjuster. The energy coarse adjuster has a transmittance (= (1−attenuation rate) on a rotatable revolver. ) × 100 (%)), and a plurality of different ND filters are arranged. By rotating the revolver, the transmittance for the incident laser beam LB can be switched from 100% in a plurality of steps. Has become. Note that a revolver similar to the revolver may be arranged in two stages so that the transmittance can be more finely adjusted by a combination of two sets of ND filters. On the other hand, the energy fine adjuster continuously fine-tunes the transmittance for the laser beam LB within a predetermined range by a double grating method, a method combining two parallel flat glass plates with variable tilt angles, or the like. . However, instead of using this energy fine adjuster, the energy of the laser beam LB may be finely adjusted by the output modulation of the excimer laser light source 1.

In FIG. 4, the beam shaping / modulating optical system 2
The laser beam LB emitted from the lens enters the fly-eye lens 5 via a mirror M for bending the optical path.

The fly-eye lens 5 is connected to the subsequent reticle 1
A number of secondary light sources are formed to illuminate 1 with a uniform illumination distribution. As shown in FIG. 4, an aperture stop (so-called σ stop) 6 of an illumination system is arranged on an emission surface of the fly-eye lens 5, and a laser beam (hereinafter, referred to as a beam) emitted from a secondary light source in the aperture stop 6 is provided. , "Pulse illumination light IL")
Is a beam splitter 7 having a small reflectance and a large transmittance.
, And the pulse illumination light IL as the illumination light for exposure transmitted through the beam splitter 7 is incident on the condenser lens 10 via the relay lens 8.

The relay lens 8 includes a first relay lens 8A
, A second relay lens 8B, and these lenses 8A, 8B
It has a fixed illumination field stop (fixed reticle blind) 9A and a movable illumination field stop 9B interposed therebetween. The fixed illumination field stop 9A has a rectangular opening, and the pulsed illumination light IL transmitted through the beam splitter 7 passes through the rectangular opening of the fixed illumination field stop 9A via the first relay lens 8A. ing. The fixed illumination field stop 9A is arranged near a conjugate plane with respect to the pattern surface of the reticle. The movable illumination field stop 9B has an opening whose position and width in the scanning direction are variable, and is arranged near the fixed illumination field stop 9A. The movable illumination field stop 9B is moved at the start and end of scanning exposure. By further restricting the illuminated field of view through the exposure, unnecessary portions (other than the shot area on the wafer to which the reticle pattern is transferred) are prevented from being exposed. In addition,
In FIG. 1, illustration of the fixed illumination field stop 9A and the movable illumination field stop 9B is omitted.

As shown in FIG. 4, the fixed illumination field stop 9A
And the pulse illumination light I passing through the movable illumination field stop 9B
L is the second relay lens 8B and the condenser lens 1
After 0, the rectangular illumination area 12R on the reticle 11 held on the reticle stage 15 is illuminated with a uniform illuminance distribution. The pattern in the illumination area 12R on the reticle 11 is projected through the projection optical system 13 through a projection magnification α (α is, for example, 1 /
The image reduced by (4, 1/5, etc.) is projected and exposed on an illumination field 12W on a wafer (photosensitive substrate) 14 coated with a photoresist. Hereinafter, the Z axis is taken in parallel with the optical axis AX of the projection optical system 13, and the scanning direction of the reticle 11 with respect to the illumination area 12R (that is, the direction parallel to the plane of FIG. 4) in a plane perpendicular to the optical axis AX. The Y direction and a non-scanning direction perpendicular to the scanning direction will be described as an X direction.

At this time, the reticle stage 15 is scanned by the reticle stage drive section 18 in the Y direction. The Y coordinate of the reticle stage 15 measured by the external laser interferometer 16 is supplied to the stage controller 17,
The stage controller 17 controls the position and speed of the reticle stage 15 via the reticle stage driving unit 18 based on the supplied coordinates.

On the other hand, the wafer 14 is mounted on a wafer stage 28 via a wafer holder (not shown). The wafer stage 28 has a Z tilt stage 19 and an XY stage 20 on which the Z tilt stage 19 is mounted.
The XY stage 20 moves the wafer 14 in the X and Y directions.
And the wafer 14 is scanned in the Y direction. The Z tilt stage 19 has a function of adjusting the position (focus position) of the wafer 14 in the Z direction and a function of adjusting the inclination angle of the wafer 14 with respect to the XY plane. The moving mirror fixed on the Z tilt stage 19 and the X and Y coordinates of the XY stage 20 (wafer 14) measured by the external laser interferometer 22 are supplied to the stage controller 17, and the stage controller 17 The position and speed of the XY stage 20 are controlled via the wafer stage drive unit 23 based on the supplied coordinates.

The operation of the stage controller 17 is controlled by a main control system (not shown) which controls the entire apparatus. At the time of scanning exposure, the reticle 1
1 through the reticle stage 15 in the + Y direction (or-
Synchronization to be scanned at a speed V _R in the Y direction), the wafer 14 via the XY stage 20 is illuminated field field 1
Speed α · V in −Y direction (or + Y direction) for 2W
_The scanning is performed at _R (α is a projection magnification from the reticle 11 to the wafer 14).

The wafer 1 on the Z tilt stage 19
An uneven illuminance sensor 21 made of a photoelectric conversion element is permanently provided in the vicinity of 4, and the light receiving surface of the uneven illuminance sensor 21 is set at the same height as the surface of the wafer 14. Illumination unevenness sensor 21
For example, a PIN-type photodiode having sensitivity in the deep ultraviolet and having a high response frequency for detecting pulsed illumination light can be used. A detection signal of the uneven illuminance sensor 21 is a peak hold circuit (not shown),
Exposure controller 2 via digital (A / D) converter
6.

The pulse illumination light IL reflected by the beam splitter 7 shown in FIG. 4 is received by an integrator sensor 25 composed of a photoelectric conversion element via a condenser lens 24, and the photoelectric conversion signal of the integrator sensor 25 is It is supplied to the exposure controller 26 as an output DS via a peak hold circuit (not shown) and an A / D converter. The correlation coefficient between the output DS of the integrator sensor 25 and the illuminance (exposure amount) of the pulse illumination light IL on the surface of the wafer 14 is obtained in advance and stored in the exposure controller 26. The exposure controller 26 controls the light emission timing and the light emission power of the light source 1 for exposure by supplying the control information TS to the light source 1 for exposure. The exposure controller 26 further controls the dimming rate in the energy modulator 3, and the stage controller 17 controls the opening and closing operation of the movable illumination field stop 9B in synchronization with the operation information of the stage system.

In this embodiment, in such a step-and-scan type projection exposure apparatus 30, FIG.
As shown in FIG. 1, an alignment shielding plate 52 is provided on the light source side of the reticle 11. By providing the shielding plate 52,
At the time of alignment, the first illumination light for alignment emits a reticle alignment mark RM (mainly the first reticle alignment mark RM) formed on the reticle 11 on the object plane side of the projection optical system 13.
The mark area is illuminated only, and the shot area is not illuminated. The alignment shielding plate 52
Can be shared by the illumination field stops 9A and 9B shown in FIG.

As shown in FIG. 1, in this embodiment, there is no hindrance in exposing the shot area of the wafer 14 through the projection optical system 13 between the projection optical system 13 and the wafer stage 28. A wafer alignment sensor 50 as a detection device is arranged at the position. This sensor 50 is preferably fixed to the projection optical system 13.

As shown in FIG. 2, the sensor 50 has a half mirror 54 and a reticle alignment mark R
The first illumination light AL1 for alignment that has been irradiated with M and passed through the projection optical system 13 is reflected by the half mirror 54, and a reticle alignment mark RM is formed on the light receiving surface 56.
Image is formed. The light receiving surface 56 is a surface optically conjugate to both the surface of the reticle 11 and the surface of the wafer 14.

In this embodiment, since the exposure illumination light emitted from the light source 1 shown in FIG. 4 is used as the alignment first illumination light AL1, the aberration is minimized with respect to the exposure illumination light. Projection optical system 13 designed in
Can form an image of the reticle alignment mark RM on the light receiving surface 56 without any problem.

In this embodiment, a layer of a fluorescent substance is formed on the light receiving surface 56, and fluorescence is generated in accordance with the pattern of the reticle alignment mark RM formed on the light receiving surface 56. This fluorescent light is used for the first alignment.
The wavelength of the illumination light AL1 is different from that of the illumination light AL1, and is light that can be detected by an image sensor 60 described later. That is, the light receiving surface 56 on which the fluorescent material layer is formed functions as a light conversion element.

The fluorescent light generated on the light receiving surface 56 passes through the half mirror 54 and enters the objective optical system 58. The objective optical system 58 includes a single or a plurality of objective lenses, and emits fluorescence generated on the light receiving surface 56 to the optical system 58.
Half mirror 62 opposite half mirror 54 across
Through to the light receiving surface of the image sensor 60, where the image of the reticle alignment mark RM is re-formed. Although there is no particular limitation on the imaging element 60, a one-dimensional or two-dimensional CCD camera or the like is used.

The second alignment mirror is located at a position optically conjugate with the image sensor 60 with respect to the half mirror 62.
The emission surface of the second light source 64 that emits the illumination light AL2 is arranged. In the present embodiment, the second light source 64 is 200 nm
It is an optical system that emits broadband light with a broad wavelength distribution of a degree, and includes, for example, a halogen lamp, a condenser lens, an optical fiber, and a filter (cuts a photosensitive wavelength region and an infrared wavelength region of a resist layer). In addition,
The sensor 50 only needs to be provided with an emission surface from the second light source 64, and does not need to include all the members constituting the second light source 64.

The alignment second illumination light AL2 emitted from the emission surface of the second light source 64 is reflected by the half mirror 62, passes through the objective optical system 58, and passes through the half mirror 5 on the opposite side.
4 illuminates the wafer alignment mark WM on the wafer 14. The reflected light from the wafer alignment mark WM is reflected again by the half mirror 54, passes through the objective optical system 58 to the half mirror 62, and then passes through the half mirror 62, and On the surface, the wafer alignment mark WM
The image of is formed.

That is, in the present embodiment, the image pickup device 60
, The image of the reticle alignment mark RM and the image of the wafer alignment mark WM are formed simultaneously. Although the specific shapes of the marks RM and WM are not particularly limited, it is preferable that the marks RM and WM be a combination of marks that can detect the amount of displacement in the two-dimensional direction. Such an example is shown in FIGS. 3A and 3B, for example. FIG. 3A shows an example in which rectangular reticle alignment marks RM are arranged inside stripe-shaped wafer alignment marks WM arranged in four directions. Further, in FIG. 3B, a wafer alignment mark WM in which mutually perpendicular stripes are formed in a cross shape is arranged inside, and a stripe-shaped reticle alignment mark RM is arranged outside the wafer alignment mark RM. It is located in.

In this embodiment, the image sensor 60 shown in FIG.
In FIG. 3, the image of the reticle alignment mark RM and the image of the wafer alignment mark WM can be simultaneously detected, and the photoelectric conversion signal is converted in a two-dimensional direction as shown in FIGS. 3 (A) and 3 (B). By detecting, it is possible to measure and output the positional deviation amount of these marks RM and WM.

The positional deviation amount data between the marks detected by the image pickup device 60 is stored in, for example, the exposure device 30 shown in FIG.
Of the reticle 11
Reticle 11 and / or wafer 1 so that exposure is performed with wafer and wafer 14 accurately aligned.
4 is controlled.

After such an alignment operation, the step-and-scan exposure is performed for each shot area on the wafer 14 as described above.

In the projection exposure apparatus 30 according to this embodiment,
The relative positional relationship between the reticle alignment mark RM and the wafer alignment mark WM is determined by the image sensor 60.
Can be measured directly and simultaneously, so that it is not necessary to perform baseline measurement, and it is possible to stably maintain high overlay accuracy without being affected by the drift of the baseline.

Further, since it is not necessary to perform the baseline measurement, it contributes to the improvement of the throughput of the alignment step and the exposure step.

In the present embodiment, since the illumination light for exposure is used as the first illumination light for alignment AL1, a light source for generating the first illumination light for alignment is not required, and the number of parts is reduced. Contribute to reduction. Further, since the illumination light for exposure is used as the first illumination light for alignment AL1, the influence of aberration can be minimized even through the projection optical system 13. Further, the degree of freedom in designing the projection optical system is higher than when the light dedicated to alignment is passed through the projection optical system 13.

Further, since the broadband light is used as the second illumination light for alignment, unlike the case where monochromatic light is used, multiple interference of light due to a resist layer formed on the wafer 14 and the like occur. Since the deterioration of the detection accuracy caused by the cause can be prevented, the detection accuracy is also improved in this respect.
Further, since broadband light is used as light for irradiating the wafer alignment mark WM, there is also an advantage that robust measurement can be performed even on an asymmetric mark WM or a rough mark WM.

When the broadband light passes through the projection optical system 13, the accuracy of positioning may be reduced due to the influence of aberration. However, in the present embodiment, the second broadband light which is the broadband light is used. Regarding the illumination light AL2, the projection optical system 13
There is no problem because it does not go through.

The present invention is not limited to the above-described embodiment, but can be variously modified within the scope of the present invention.

For example, instead of forming a fluorescent substance layer on the light receiving surface 56 of the wafer alignment sensor 50 shown in FIG. 2, this surface 56 may be used as a light receiving surface of an image sensor other than the image sensor 60. Alternatively, the image of the reticle alignment mark RM formed on the light receiving surface 56 may be guided to a light receiving surface of an image sensor different from the image sensor 60 via an optical member. In these cases, the image of reticle alignment mark RM is
The image of M is detected on the light receiving surface of an image sensor different from the image sensor 60 on which the image is formed. Therefore, it is necessary to determine the amount of displacement of these marks by comparing the electrical signals separately detected by these image sensors with another circuit.

Further, in the alignment sensor 50 in the above-described embodiment, the second light source 64 is provided at a position different from the image sensor 60, but the second light source may be mounted inside the image sensor 60. .

In the above embodiment, the reticle
Although the images of the alignment mark RM and the wafer alignment mark WM are formed on the image sensor to detect the mark position, the present invention is not limited to this, and other position detection methods may be employed. For example, a configuration may be adopted in which a mark position is detected using interference of laser light. As a method of detecting the mark position using the interference of laser light, a diffraction grating mark is irradiated with two coherent light beams, and the phase of the interference light composed of diffracted light generated in the same direction from the mark is detected. There is known a laser interference alignment method (LIA) for performing position detection on the basis of a laser beam.

In the above-described embodiment, the step
The reduction projection scanning exposure apparatus (scanning stepper) of the AND scan method has been described. For example, the illumination light for exposure is irradiated on the entire surface of the reticle pattern while the reticle 11 and the wafer 14 are stationary. A step-up / repeat type reduction projection type exposure apparatus (stepper) for batch exposure of one defined area (shot area) on the wafer 14 to which a reticle pattern is to be transferred, and a mirror projection type or proximity type. The present invention can be similarly applied to an exposure apparatus. In the projection optical system 13, all the optical elements are refraction elements (lenses). However, the projection optical system 13 may be an optical system including only reflection elements (mirrors and the like), or a refraction element and a reflection element ( Catadioptric optical system comprising a concave mirror, a mirror, etc.). Further, the projection optical system 13 is not limited to the reduction optical system, but may be an equal-magnification optical system or an enlargement optical system.

Further, as a light source, EUV (Extreme Ultra) having an oscillation spectrum in a soft X-ray region is used.
The present invention can also be applied to a reduced projection type scanning exposure apparatus using a SOR or a laser plasma light source that generates Violet (Violet), or a proximity type X-ray scanning exposure apparatus.

Further, the alignment apparatus and method according to the present invention are not only applied to a projection exposure apparatus, but also in other apparatuses, a first member disposed on the object plane side of a projection optical system, and a projection optical system. The present invention can be applied to all cases where it is desired to align the second member disposed on the image plane side of the system with high optical precision and high throughput.

[0083]

As described above, according to the present invention, the first member (for example, a mask) disposed on the object plane side of the projection optical system and the first member disposed on the image plane side of the projection optical system. 2
It is possible to provide a projection exposure apparatus, an alignment apparatus, and an alignment method capable of optically aligning a member (for example, a photosensitive substrate) with high precision and high throughput.

[Brief description of the drawings]

FIG. 1 is a schematic view of a projection exposure apparatus according to one embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of the alignment sensor shown in FIG.

FIGS. 3A and 3B are schematic diagrams showing a relationship between a reticle alignment mark and a wafer alignment mark.

FIG. 4 is an overall configuration diagram of a projection exposure apparatus.

FIG. 5 is a schematic perspective view of a projection exposure apparatus having an alignment apparatus according to a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Exposure light source 11 ... Reticle (mask) 13 ... Projection optical system 14 ... Wafer (photosensitive substrate) 17 ... Stage controller 30 ... Projection exposure apparatus 50 ... Wafer alignment sensor 52 ... Shielding plate 54, 62 ... Half mirror Reference numeral 56: Light receiving surface 58: Objective optical system 60: Image sensor 64: Second light source RM (RMA, RMB): Reticle alignment
Mark WM ... Wafer alignment mark

Claims (11)

[Claims] 1. A projection exposure apparatus for transferring a mask pattern onto a photosensitive substrate via a projection optical system, comprising: a first mark disposed on one of an object plane and an image plane of the projection optical system; A first illumination system that irradiates the first illumination light; and a second illumination light having a wider wavelength width than the first illumination light, on a second mark disposed on the other of the object plane side and the image plane side of the projection optical system. And a detection device that receives light generated from the first mark and the second mark, respectively, and outputs a signal corresponding to a relative positional relationship between the first mark and the second mark. A projection exposure apparatus comprising: 2. The first illumination system emits illumination light having substantially the same wavelength as the exposure illumination light applied to the mask, and the detection device generates the illumination light from the first mark and emits the projection optical system. 2. A light receiving element which receives light passing therethrough.
3. The projection exposure apparatus according to 1. 3. The method according to claim 1, wherein the first mark is arranged on an object plane side of the projection optical system, and the first illumination system is also used as an exposure illumination system for irradiating the exposure illumination system to the mask. 3. The projection exposure apparatus according to claim 2, wherein: 4. The second illumination system emits broadband light having a wavelength different from that of the first illumination light, and the detection device receives light generated from the second mark without passing through the projection optical system. The projection exposure apparatus according to claim 1, wherein: 5. The detection device according to claim 1, wherein the detection device has an objective optical system for guiding light generated from the first mark and the second mark to the same image pickup device.
The projection exposure apparatus according to any one of the above. 6. The detection device is disposed on the second mark side with respect to the projection optical system, and generates light from the first mark, passes through the projection optical system, and generates light from the second mark. The projection exposure apparatus according to claim 5, further comprising an optical member that causes light to enter the objective optical system. 7. The projection device according to claim 5, wherein the detection device includes a light conversion element that converts light generated from the first mark into light that can be detected by the image pickup device. Exposure equipment. 8. The method according to claim 1, wherein the second mark is formed on the photosensitive substrate, and a wavelength of the second illumination light is different from a wavelength range in which the photosensitive substrate is exposed.
The projection exposure apparatus according to any one of the above. 9. The method according to claim 1, wherein the first mark is formed on the mask, and a signal output from the detection device is used for alignment between the mask and the photosensitive substrate. The projection exposure apparatus according to any one of the above. 10. An alignment apparatus for optically positioning a first member disposed on an object plane side of a projection optical system and a second member disposed on an image plane side of a projection optical system. A first illumination system which irradiates a first mark arranged on the first member side with first illumination light; and a second mark arranged on the second member side has a wavelength width wider than the first illumination light. A second illumination system for irradiating a second illumination light having a large width, and receiving light generated from the first mark and the second mark, respectively, and generating a signal corresponding to a relative positional relationship between the first mark and the second mark. An alignment device, comprising: a detection device for outputting. 11. An alignment method for optically aligning a first member arranged on an object plane side of a projection optical system and a second member arranged on an image plane side of a projection optical system. Irradiating a first mark disposed on the first member side with first illumination light; and applying a second mark disposed on the second member side to a second mark having a wider wavelength width than the first illumination light. (2) irradiating illumination light; and receiving light generated from each of the first mark and the second mark, and outputting a signal corresponding to a relative positional relationship between the first mark and the second mark. Alignment method.