JP3265503B2 - Exposure method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of illuminating a rectangular or arcuate illuminated area with exposure light, and scanning a mask and a photosensitive substrate in synchronism with the illuminated area. A so-called slit scan exposure method and an exposure apparatus for sequentially exposing a photosensitive substrate,
It is particularly suitable for use when light having high spatial coherence is used as exposure light.

[0002]

2. Description of the Related Art Conventionally, when a semiconductor device, a liquid crystal display device, a thin film magnetic head, or the like is manufactured by using photolithography technology, a photomask or a reticle (hereinafter, referred to as a "reticle") has been used.
2. Related Art A projection exposure apparatus that exposes a pattern of a “reticle” onto a substrate (a wafer or a glass plate or the like) coated with a photoresist or the like via a projection optical system is used. In such a projection exposure apparatus, an excimer laser light such as a KrF excimer laser or an ArF excimer laser, or an ultraviolet laser light such as a harmonic of an argon laser is used in order to shorten the exposure light and improve the resolution. It has come to be used as exposure light.

However, the laser light has a high spatial coherence (coherence), and causes interference fringes called a speckle pattern while passing through the illumination optical system, which causes uneven illuminance on the reticle and the substrate. is there. Therefore, when a laser beam is used as the exposure light in a projection exposure apparatus of a collective exposure method such as a conventional ordinary stepper, in order to reduce illuminance unevenness due to a speckle pattern, a fly-eye in an illumination optical system is used. A vibrating mirror was placed in front of the lens (optical integrator).
Then, during one exposure, the laser beam incident on the optical integrator is scanned by the vibrating mirror, thereby performing the exposure while changing the phase of the speckle pattern (interference fringe) generated on the reticle and the substrate. ,
The exposure amount over the entire surface of each shot area on the substrate was made uniform. In this case, by oscillating the vibrating mirror so that the phase of the interference fringes changes by 2π during one exposure, the contrast of the distribution of the exposure amount on the substrate is minimized.

[0004]

Recently, the size of one chip of a semiconductor device has been increasing, and in a projection exposure apparatus, a large area pattern for exposing a pattern having a larger area on a reticle onto a substrate is required. Is required. In order to increase the area of the transferred pattern and to limit the exposure field of the projection optical system, an illumination area such as a rectangle, an arc, or a hexagon is referred to as a “slit illumination area”.
A so-called slit scan exposure type projection exposure apparatus has been developed in which a reticle and a photosensitive substrate are synchronously scanned to sequentially expose a pattern on the reticle onto the substrate. Even in such a slit scan exposure type projection exposure apparatus, when light having high spatial coherence such as laser light is used as exposure light, it is necessary to reduce illuminance unevenness due to a speckle pattern.

However, in the slit scan exposure method, since the reticle and the substrate are scanned, the phase at which the Supplekle pattern appears changes with time. Therefore, first, the scanning direction of the reticle and the substrate becomes a problem. Next, when using the vibrating mirror used in the batch exposure method,
The problem is how to control the vibrating mirror in accordance with the scanning direction and the scanning speed of the reticle and the substrate.

For example, FIGS. 7A to 7D show a state in which the reticle R is scanned in the X direction (scanning direction SR) with respect to the slit-shaped illumination area 51, and is a view from the state of FIG. 7D, the pattern area PA of the reticle R is gradually scanned by the illumination area 51. Accordingly, in the pattern area PA of the reticle R, scanning is substantially performed in the X direction, but Y is perpendicular to the X direction.
In the scanning direction and the non-scanning direction, the effect of the speckle pattern differs between the scanning direction and the non-scanning direction.

In view of the foregoing, it is an object of the present invention to minimize illuminance unevenness due to a speckle pattern when light having high spatial coherence is used as exposure light in an exposure method and an exposure apparatus of a slit scan exposure method. And

[0008]

The first exposure apparatus according to the present invention SUMMARY OF THE INVENTION may, for example, as shown in FIGS. 1 and 2, space coherency
(1) for generating illumination light (LB ₀ ) having a reference
An illumination optical system (2 to 14) for illuminating an illumination area (15) having a predetermined shape with the illumination light; a mask (R) having a predetermined pattern formed relative to the illumination area (15); Relative scanning means (32, 32) for synchronously scanning the substrate (W)
34, 35, RST, WST) and has its substrate
In an exposure apparatus for scanning and exposing (W) , illumination light (LB)
_The direction (direction H) of high spatial coherence of ( ₀ ) is the same as the relative scanning direction (direction SR) between the illumination region (15) having a predetermined shape and the mask (R).

A second exposure apparatus according to the present invention comprises a pulse light source (1) for generating pulse light (LB ₀ ) having spatial coherence , as shown in FIGS. 1 and 2, for example.
An illumination optical system (2 to 14) for illuminating an illumination area (15) having a predetermined shape with the pulse light; a mask (R) having a predetermined pattern formed relative to the illumination area (15);
Relative scanning means (32, 3) for synchronously scanning the substrate (W)
4, 35, RST, WST) and the substrate (W)
In an exposure apparatus for scanning exposure and a relative scanning velocity of the illumination area having a predetermined shape (15) and a mask (R), the relative scanning of the speckle pattern of the pulsed light in the illumination region (15) Phase variable means (8, 9) for changing the phase of the speckle pattern of the pulse light in the illumination area (15) for each pulse light in accordance with the pitch in the direction (direction SR). .

In this case, spatial coherence detecting means (17, 18) for detecting the spatial coherence of the pulse light.
And a control means (32) for controlling the operation of the phase variable means (8, 9) in accordance with the spatial coherence of the pulse light detected in this way. Next, the book
A third exposure apparatus according to the present invention has spatial coherence
A light source that generates an illuminating light,
The illumination optical system that illuminates the bright area and the illumination area
A mask and substrate on which a relatively predetermined pattern is formed
Relative scanning means for scanning synchronously, and scanning the substrate.
In an exposure apparatus that performs inspection and exposure,
The speckle pattern of the illumination light
Displacing means for displacing with the
The mask and the substrate are moving with respect to the area
Of the speckle pattern formed in the illumination area
Control means for controlling the displacement means so that the effects are reduced
And a step. In addition, the fourth dew according to the present invention.
The optical device generates illumination light having spatial coherence
A light source and an illumination for illuminating an illumination area of a predetermined shape with the illumination light.
Bright optics and a predetermined pattern relative to the illumination area.
Synchronously scans the mask and substrate on which the pattern has been formed.
Exposure apparatus having scanning means for scanning and exposing the substrate
Measuring instrument that measures the divergence angle of the illumination light
Based on the step and the measured divergence angle information,
Control means for controlling the exposure conditions of the plate.
You. Further, the fifth exposure apparatus according to the present invention provides a spatial
A light source for generating illumination light having a
Illumination optical system for illuminating shaped illumination area and its illumination area
Mask with a predetermined pattern formed relative to
And relative scanning means for scanning the substrate and the substrate synchronously.
In an exposure apparatus for scanning and exposing a substrate, an illumination optical system is provided.
Converts the illumination light from the light source into a first illumination of a first polarization component.
Polarizing means for separating light and second illumination light of a second polarization component
And the first illumination light and the second illumination light are
The illuminance distribution on the
Things. Next, a first exposure method according to the present invention includes:
Tokoro shaped shaped illumination area in the illumination light having a spatial coherence
And illuminate the area relative to the illumination area.
The mask and substrate on which a fixed pattern is formed
Exposure method for scanning and exposing the substrate by inspecting
The speckle pattern formed in the illumination area
The direction of high contrast of the
The relative scanning direction between the area and its mask
It is. Further, the second exposure method according to the present invention provides a
When illuminating the illumination area with illumination light having coherence
In addition, a predetermined pattern relative to the illumination area
By synchronously scanning the formed mask and substrate
Thus, in an exposure method for scanning and exposing the substrate,
Illumination light has a cross-sectional shape with a longitudinal direction and a lateral direction
In the transverse direction of the cross-sectional shape of the illumination light emitted from the light source
Is the relative scanning direction between the illumination area and the mask.
It is made to match. In addition, the present invention
Exposure method 3 employs illumination light having spatial coherence.
Along with illuminating a fixed-shaped illumination area,
A mask on which a predetermined pattern is relatively formed, and
Scanning a board by scanning it synchronously
In the exposure method for exposing, the illumination is performed during the scanning exposure.
The mask and the substrate are moving with respect to the region
Speckle pattern formed in the illumination area
Within the illuminated area so that the effects of
This is to displace the circle pattern.

[0011]

According to the first exposure apparatus of the present invention, a direction having high spatial coherence (degree of coherence) is measured in advance in a plane perpendicular to the light beam of the illumination light (LB ₀ ). In the illumination area (15) having a predetermined shape, the direction of high spatial coherence is matched with the scanning direction (SR direction) relative to the mask (R). Therefore, as shown in FIG. 4, for example, the illuminance distribution in the scanning direction (SR direction) of the speckle pattern by the illumination light formed on the illumination area (15) is relatively large at a predetermined pitch as indicated by a distribution curve 40. Varies with amplitude. Further, the illuminance distribution in the non-scanning direction (Y direction) of the speckle pattern on the illumination area (15) is relatively flat like a distribution curve 41. In this case, in the scanning direction, the illuminance distribution at each point on the mask (R) changes as indicated by a distribution curve 40, and is substantially the same as when scanning with a vibrating mirror. Also, since the illuminance unevenness is originally small in the non-scanning direction, the illuminance unevenness is reduced over the entire surface of the mask (R) and the substrate (W).

According to the second exposure apparatus of the present invention,
Pulse light is used as illumination light. The pulsed light is, for example, an excimer laser beam in the far ultraviolet region (wavelength is,
nm), it is not easy to eliminate chromatic aberration in the optical system. Therefore, the pulse light source (1) generates pulsed light having a narrowed spectral line width by using a diffraction grating and a slit. Therefore, in FIG. 1, the pulse light (LB ₀ ) emitted from the light source (1) has a high spatial coherence and a narrow beam width in the horizontal direction (H direction), but has a narrow beam width in the vertical direction (V direction). The spatial coherence is low and the beam width is wide. Therefore, in the present invention, the horizontal direction of the pulse light (LB ₀ ) emitted from the light source (1) is set to the scanning direction of the slit-shaped illumination area (15) on the mask (R).

In this case, the ratio of the width in the horizontal direction to the width in the vertical direction of the pulse light (LB ₀ ) is generally determined by the width in the scanning direction and the width in the non-scanning direction of the ordinary slit-shaped illumination area (15). Is smaller than the ratio of
It is necessary to increase the horizontal width of the pulse light (LB ₀ ) using the cylindrical lenses 38 and 39.
At this time, the spread angle of the incident pulse light (LB ₀ ) is θ ₁ , and the focal length of the preceding cylindrical lens 38 is f
₁ , the focal length of the subsequent cylindrical lens 39 is set to f ₂
Then, the divergence angle θ ₂ of the pulse light (LB) emitted from the cylindrical lens 39 is as follows.

Θ ₂ = (f ₁ / f ₂ ) θ ₁ (1) Therefore, in order to increase the horizontal beam width, f ₁ <f
_Assuming that ₂ , pulse light (L
The spread angle θ ₂ of B) becomes small. θ ₁ > θ ₂ (2) Accordingly, when the beam width is expanded in the horizontal direction, the spatial coherence of the illumination area (15) in the scanning direction (SR direction) is further increased as shown in FIG. Therefore, a speckle pattern with high contrast is formed in the scanning direction.
On the other hand, since the contrast of the speckle pattern in the non-scanning direction is low, the illuminance unevenness is small in the non-scanning direction.

The illumination distribution in the scanning direction of the illumination area (15) is, for example, as shown by a distribution curve 40 in FIG. If the scanning direction of the mask and the substrate is selected in this direction, waves of various phases are superimposed as shown in FIG. 5B due to the phase shift due to the scanning, so that speckle can be reduced by the integration effect. However, when some control is not performed, the timing of pulse emission and the phase of the speckle pattern substantially coincide with each other depending on the scanning speed, and at a certain irradiation point on the mask (R), for example, as shown in FIG. a) Position 4
The exposure is performed in the order of 0C, 40F,..., And the exposure is performed in the order of the positions 40B, 40E,... At another irradiation point, so that the integration effect cannot be expected and the illuminance unevenness may not be reduced.
In order to avoid this, the positions 40C and 40C in FIG.
At F and 40I, when the scanning speed is such that pulsed light emission is performed, the scanning control is performed such that the oscillating mirror is scanned, and when the light is emitted at the position 40F, the lateral shift is δA, and when the light is emitted at the position 40I, the lateral shift is δB. I do.

Thus, each irradiation point on the mask (R) is
That the distribution curve 40, 42, 43 of FIG. 5 (b), are equally divided in accordance with the number of pulses to be exposed by illumination with scan pet cycle pattern of different phases, the integrated exposure amount is averaged, the mask Illumination unevenness in the scanning direction on (R) is reduced. That is, at an arbitrary irradiation point on the mask (R),
When n and m are integers, the phase in the scanning direction on the distribution curve 40 for each pulse emission is 0, 2mπ + (2π / n), 4mπ +
(4π / n), 6mπ + (6π / n), ..., 2 (n
By controlling the operation of the phase varying means (8, 9) so that -1) mπ + 2 (n-1) π / n,..., Illuminance unevenness in the scanning direction is reduced.

A spatial coherence detecting means (17, 18) for detecting the spatial coherence of the pulse light;
When the control means (32) for controlling the operation of the phase varying means (8, 9) in accordance with the spatial coherence of the pulse light detected in this way is provided, The operation of the phase varying means (8, 9) is controlled so that the illuminance unevenness caused by the speckle pattern on the mask (R) and the substrate (W) is minimized.

[0018]

An embodiment of the present invention will be described below with reference to the drawings. In this embodiment, the present invention is applied to a slit scan exposure type projection exposure apparatus using a pulse oscillation type laser light source as a light source of exposure light. FIG. 1 shows an optical system of the projection exposure apparatus of the present embodiment. In FIG. 1, a laser beam LB ₀ in the far ultraviolet region (wavelength is, for example, 248 nm) emitted from an excimer laser light source 1 is reflected by an ultraviolet reflecting mirror M1, The light enters the beam shaping optical system 2 including a cylindrical lens via M2, M3, and M4.
Laser beam LB emitted from excimer laser light source 1
₀ cross-sectional shape is substantially narrower elongated rectangular than the width of the width in the vertical direction in the horizontal direction (H direction) (V direction), the beam shaping optical system 2, the horizontal width of the laser beam LB ₀ spread, A laser beam LB having a cross-sectional shape having substantially the same aspect ratio as that of a slit-shaped illumination area 15 described later is emitted.

FIG. 3 shows the configuration of the beam shaping optical system 2. As shown in FIG.
_{In the case of 0} , the horizontal width of the cross-sectional shape is enlarged to f ₂ / f ₁ times through a cylindrical lens 38 having a focal length f ₁ and a cylindrical lens 39 having a focal length f ₂ (f ₂ > f ₁ ). Assuming that the divergence angle of the incident laser beam LB ₀ is θ ₁ , the divergence angle θ ₂ of the emitted laser beam LB is
The spread angle θ ₁ is reduced to f ₁ / f ₂ . In general, for the spatial coherence of the light beam is high enough divergence angle is small, the spatial coherence of the horizontal direction of the laser beam LB emitted (H direction) has been higher than the laser beam LB ₀ incident.

Returning to FIG. 1, the laser beam LB emitted from the beam shaping optical system 2 is bent by the ultraviolet reflecting mirror M5 and enters the beam expander (or zoom lens) 3 to reach a predetermined sectional dimension. The cross-sectional shape is enlarged. The parallel laser beam LB emitted from the beam expander 3 is applied to a quartz prism 4 as a polarizing means.
And split into two orthogonal polarization components. The two polarized components separated in this way enter the quartz glass prism 5 for optical path correction, and the traveling direction of the beam is corrected. Thereafter, the laser beams of the two polarization components pass through the first-stage fly-eye lens 6 and relay lens 7 and are bent by the vibrating mirror 8. The oscillating mirror 8 is driven by the driving device 9 to scan the laser beam within a predetermined angle range on a horizontal plane by an appropriate control method.

A laser beam scanned by the vibrating mirror 8 is incident on the second-stage fly-eye lens 11 via the relay lens 10, and a large number of tertiary light sources (spot lights) are formed on a focal plane on the emission side. Then, the laser beams from the many tertiary light sources are further condensed by the condensing lens 12, bent by the mirror 13, and incident on the main condenser lens 14. Laser beams from a number of tertiary light sources are irradiated by the main condenser lens 14 on the illuminated area 15 having a rectangular shape whose width in the short side direction on the reticle R is D. The pattern image in the illumination area 15 is projected onto the rectangular exposure area 1 on the wafer W via the projection optical system PL.
6 is imaged and projected.

In this case, the Z axis is set in parallel with the optical axis of the projection optical system PL, and the X axis in the XY plane perpendicular to the optical axis is set in the short side direction of the rectangular illumination area 15. In this example, the projection magnification of the projection optical system PL is β, and the illumination area 1
5 with respect to the reticle R in the X direction (the
R ”), the wafer W is scanned at a speed β · V in the −X direction (this is referred to as a“ scanning direction SW ”) in synchronization with scanning at a speed V, thereby forming a pattern area of the reticle R. The circuit pattern image in the PA is sequentially projected and exposed on the shot area of the wafer W.

In FIG. 1, in order to check the spatial coherence of the excimer laser light, a condenser lens L1 is installed behind the ultraviolet reflecting mirror M5, and the light leaking from the ultraviolet reflecting mirror M5 is reflected after the condenser lens L1. Focus on the side focus position,
A two-dimensionally distributed leakage light is received by a two-dimensional image pickup device 17 composed of a CCD installed at the focal position. And
The image signal from the two-dimensional image sensor 17 is processed by the image processing system 18 to measure the divergence angle of the laser beam. Since the divergence angle of the laser beam is inversely proportional to the spatial coherence, the spatial coherence in the scanning direction SR and the non-scanning direction on the illumination area 15 can be calculated from the measured divergence angle.

FIG. 2 shows a control system of the projection exposure apparatus of FIG. 1. In FIG. 2, the excimer laser light source 1 includes:
A laser tube 21 enclosing a gas serving as a medium for laser oscillation and an electrode for oscillation trigger; a front mirror 22 having a predetermined reflectance (less than 100%) constituting a resonator; a rear mirror 23 of the resonator; Opening plate 29 for
A prism 24 for wavelength selection and wavelength narrowing, a reflection type diffraction grating 25, and the like are provided as optical elements. Further, the excimer laser light source 1 has an oscillation control unit 26 for applying a high voltage to the electrodes in the laser tube 21 to oscillate, and a diffraction device for constantly keeping the absolute wavelength of the oscillated laser beam constant. A wavelength adjustment drive unit 27 for adjusting the tilt angle of the grating 25, a drive unit 28 for adjusting the tilt of the rear mirror 23, and the like are provided.

A part of the laser beam emitted from the front mirror 22 is guided to a wavelength detector (spectroscope, etc.) 31 via a beam splitter 30, and the wavelength detector 31
Detects the wavelength of the laser beam, and transmits the detected wavelength to the wavelength adjustment drive unit 27. The wavelength adjustment drive unit 27 changes the inclination angle of the diffraction grating 25 according to the wavelength detected by the wavelength detector 31 so that the difference from a predetermined absolute wavelength falls within a standard. In addition, a signal corresponding to the beam divergence angle detected by processing the image signal from the two-dimensional image sensor 17 by the image processing system 18 (specifically, the size of the beam spot formed on the two-dimensional image sensor 17) Signal)
The signal is fed back to the drive unit 28 of the rear mirror 23 of the excimer laser light source 1, and is also sent to the main controller 32 that controls the operation of the entire apparatus. The drive unit 28 changes the tilt angle of the rear mirror 23 when the value of the divergence angle of the beam actually measured with respect to a predetermined value is out of the allowable range.

The positioning and scanning of the reticle R of FIG. 1 are performed by the reticle stage RST of FIG. 2, and the positioning and scanning of the wafer W are performed by the wafer stage WS of FIG.
Performed by T. The reticle stage RST scans the reticle R in order to sequentially change the irradiation range of the reticle R on which the pattern of one chip is drawn. Wafer stage WST is controlled so that a pattern image of reticle R is exposed to each of a plurality of shot areas on wafer W.
It has a function of moving the wafer W in the step and repeat method in the direction and the Y direction, and a function of scanning the wafer W in synchronization with the scanning of the reticle R according to the irradiation range of the reticle R.

Main controller 32 controls the oscillation of excimer laser light source 1 via oscillation controller 26, and controls wafer stage WST and reticle stage R via wafer stage control system 34 and reticle stage control system 35, respectively.
Control the operation of ST. Then, the main control device 32 controls the amplitude and cycle of the vibration of the vibrating mirror 8 via the driving device 9. The main controller 32 includes a keyboard 36 as an input device and a coordinate input device (a so-called mouse) 37.
And a display unit (CRT display, meter, etc.) 33 as an output device, and the like. The keyboard 36 and the coordinate input device 37 are used for exposure processing of a certain wafer.
In addition to specifying in advance how many pulses should be exposed per shot area, it is used for various sequence settings and parameter settings.

The main controller 32 receives information on the beam divergence angle of the laser beam from the excimer laser light source 1 during the preliminary oscillation from the image processing system 18 and minimizes the speckle pattern without lowering the throughput. The oscillation frequency optimized as described above and the number of pulses of the laser beam applied to one shot area on the wafer W are determined, and a command is issued to the oscillation control unit 26. At the same time, the main controller 32 determines the oscillation period, amplitude, and phase of the oscillation mirror 8 and issues a command to the driving device 9, and also provides the reticle stage control system 35 and the wafer stage control system 34 with optimal scanning. Decide the speed and issue a command.

Next, a configuration for reducing uneven illuminance on the reticle R and the wafer W in this embodiment will be described. First, in this embodiment, the spatial coherence of the laser beam LB ₀ emitted from the excimer laser light source 1 in FIG. 1 is high in the horizontal direction (H direction). Therefore, the illumination optical system is configured so that the direction in which the spatial coherence of the laser beam LB ₀ is high is the short side direction of the illumination area 15, that is, the scanning direction SR. Thus, the speckle pattern of the laser beam formed on the illumination region 15 on the reticle R has a high contrast in the scanning direction SR and a low contrast in the non-scanning direction (Y direction).

The speckle pattern generated on the reticle R and the wafer W in FIG. 1 includes a periodic component corresponding to the arrangement of the lens elements of the fly-eye lenses 6 and 11, and the interference pattern Becomes higher in the X direction on the reticle R. In this example, in order to reduce the contrast of the speckle pattern, the laser beam LB is separated into two polarized component laser beams having a predetermined angle by a quartz prism 4 as a polarizing means, and the reticle R is illuminated. I have. The illuminance distribution I (X) (relative value) in the scanning direction (X direction) of the illumination region 15 by the laser beam of the first polarization component of the two polarization components is represented by a distribution curve 40 in FIG. And periodically changes at a predetermined pitch. On the other hand, the illuminance distribution I (X) by the laser beam of the second polarization component is shifted by a half pitch in the X direction with respect to the distribution curve 40 as shown by the distribution curve 44. Thus, the entire illuminance distribution I
(X) becomes the distribution curve 45 in FIG. 6B, and the amplitude of the fluctuation of the illuminance distribution is reduced.

FIG. 4 shows an illumination area 15 on the reticle R of this embodiment.
In FIG. 4A, an illumination area 15 having a width D in the scanning direction SR (X direction) is formed on the reticle R. Then, the illuminance distribution I (X) in the X direction of the illumination area 15 changes with a relatively large amplitude at a predetermined pitch as shown by a distribution curve 40 in FIG. (Y) is the distribution curve 4 in FIG.
It is almost flat like 1. Therefore, the illuminance unevenness in the Y direction, which is the non-scanning direction, is reduced. In this example, uneven illuminance in the X direction is eliminated by scanning the illumination area 15 with the reticle R and scanning the laser beam with the vibrating mirror 8 in FIG.

FIG. 5A shows a distribution curve 40 corresponding to the illuminance distribution I (X) in the scanning direction (X direction) per pulse light in the illumination area 15, from the origin to the X coordinate D. Is the interior of the illumination area 15 in FIG. When the reticle R is scanned in the X direction with respect to the illumination area 15, each irradiation point on the reticle R is set as shown in FIG.
(The same applies to (b)).

In this embodiment, pulse light emission is performed, and when the pitch of the distribution curve 40 is PX, and the required number of pulses obtained from the energy density of one pulse and the resist sensitivity is n, 0, 0 pulse light emission is performed in n times of pulse light emission. PX / n, 2PX / n,
.., (N-1) The scanning speed (0, PX / n, 2P) at which a distribution curve having a peak at each position of PX / n is obtained.
It is not necessary that a distribution curve having peaks in the order of X / n,..., (N-1) PX / n appears. It is sufficient that all the distribution curves having peaks at each position can be obtained by n times of pulse emission. Also, if n is sufficiently large, the pitch PX is set to n /
There may be a case where a distribution curve having a peak at an equally divided position may be obtained. ) Coincides with a predetermined speed (a value V = (D / n) f obtained by dividing the irradiation area D by the required number n of pulses and multiplying the oscillation frequency f of the laser) by the vibrating mirror 8 in FIG. Irradiance unevenness on the reticle R and the wafer W is reduced most efficiently.

For example, when the required number of pulses is 3, 1
The reticle R moves in the X direction by D / 3 for each pulse.
Therefore, as shown in FIG. 5A, at a certain irradiation point (X = 0) on the reticle R, the positions 40A and 40 with the interval D / 3 are set.
Exposure is performed in the order of E, 40I,..., And when the exposure amount distribution in the X direction is viewed, the pulses of the distribution curves 40, 42, and 43 in FIG. Becomes extremely small. The distance that the reticle R moves for each pulse is set in advance to an integral fraction of the width D of the illumination area 15 in the scanning direction.

However, since the scanning speed of the reticle R and the wafer W is determined by an appropriate exposure amount on the wafer W as described later, the above conditions may not always be satisfied. In such a case, the oscillating mirror 8 in FIG. 1 is scanned, and 0, PX / n, 2PX / n,.
It is necessary to obtain a distribution curve having a peak at the position of PX / n.

Specifically, when the required number of pulses is 4, 1
The reticle R moves by D / 4 in the X direction for each pulse. Therefore, at a certain irradiation point (X = 0) on the reticle R as shown in FIG.
Exposure is performed in the order of 40D, 40G, 40K,..., And at another point, a point separated by D / 6 from the position of X = 0,
Since exposure is performed in the order of the positions 40C, 40F, 40I, and 40L, the distribution of the integrated exposure amount in the X direction is represented by a distribution curve 40.
Are superimposed, and the light amount unevenness is not reduced at all.
Then, the vibration mirror 8 is scanned. For example, position 40F
At the time of exposure at PX / 4 and PX / at the position 40I.
If the phase is changed by scanning the vibrating mirror 8 by 3 PX / 4 at the position 2 at the position 40L, waves of four different phases are superimposed as shown in FIG. 5C, and the illuminance unevenness becomes extremely small. In FIG. 5 (c), distribution curves 46, 47, 48
Are obtained by changing the phases of the distribution curve 40 by PX / 4, PX / 2, and 3PX / 4 by the vibrating mirror 8, respectively.

Next, the scanning speed of the reticle R and the wafer W will be described. First, the scanning speed of the wafer W
(Determined by the sensitivity of the resist applied on the wafer W) and the amount of energy for each pulse. In the case of a light source such as the excimer laser light source 1, since the amount of energy emitted for each pulse is different, the light is reduced in the illumination optical system and the number of pulses is increased to expose the wafer W. The amount of energy for each pulse is determined so that the variation in the amount of exposure given to the laser beam is reduced.

Assuming that the appropriate exposure amount given to the wafer is E and the energy amount per pulse (average energy amount) is E _P ,
The number of exposure pulses is represented by E / E _P , and the length in the scanning direction of the area illuminated on the reticle R at one time (that is, the illumination area 15).
Of the reticle R per pulse is (E _P / E) D, and the scanning of the reticle R is performed when the oscillation frequency of the excimer laser light source 1 is f [Hz]. The speed V is set to the value of the following equation.

V = (E _P / E) f · D (3) In the above embodiment, the non-scanning direction of the illumination area 15 (FIG. 4)
Although the scanning of the speckle pattern in the (Y direction) was not performed, in order to further reduce the illuminance unevenness in the non-scanning direction, for example, the vibration mirror 8 in FIG. It is also desirable to scan the speckle pattern.

In FIG. 4, in order to vibrate the speckle pattern in both the scanning direction SR (X direction) and the non-scanning direction (Y direction), the spec The pattern may be vibrated.

The following method can be used to match the direction in which the spatial coherence is high with the scan direction. If the reticle and wafer can be scanned in both the X and Y directions on the side of the exposure apparatus main body, even after the main body and the laser light source are connected, the direction in which the coherence is high only needs to be the scanning direction. . At this time, it is necessary to set the shape of the illumination area by, for example, a reticle blind so that the determined scanning direction is the short direction of the illumination area on the reticle. The direction of high coherence of the laser beam incident on the illumination optical system of the exposure apparatus may be adjusted by, for example, a plurality of mirrors so that the direction of high spatial coherence of the laser light from the laser light source coincides with the scan direction.
However, it may be necessary to adjust the fly-eye lens or the like. In general, it is desirable to set up the device in consideration of the direction of high coherence.

The present invention is not limited to the above embodiment,
For example, various configurations may be used without departing from the gist of the present invention, such as when using laser light composed of harmonics of a YAG laser as exposure light, or when using continuous light such as i-line of a mercury lamp as exposure light. Of course, it can be taken.

[0043]

According to the present invention, the direction having high contrast of the interference fringes of the scan pet cycle pattern matches the scanning direction,
Irradiance unevenness in the scanning direction is reduced by relative scanning between the illumination area and the mask (substrate), and thus there is an advantage that unevenness in illuminance due to a speckle pattern is reduced.

Further, according to the present invention , the illumination area is masked.
When scanning the disk and substrate relative to each other,
Since the speckle pattern is displaced,
Reduction by relative scanning of bright area and mask (substrate)
Together with the effect of uneven illuminance due to speckle pattern
It can be extremely small.

In particular, the relative position between the illumination area and the mask (substrate)
Scanning speed and pulse light specifications in the illumination area
According to the relative scanning direction pitch of the pattern.
The phase of the speckle pattern of the pulsed light in the bright region
By changing for each light, the illuminance unevenness due to the speckle pattern can be further reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a projection exposure apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a control system of the projection exposure apparatus according to the embodiment.

FIG. 3 is a configuration diagram showing an example of a beam shaping optical system 2 of FIG.

FIG. 4 is a perspective view showing an illuminance distribution of an illumination area 15 on the reticle R.

5A is a diagram showing an illuminance distribution in a scanning direction of an illumination area 15 on a reticle R, and FIGS. 5B and 5C are illuminances in a scanning direction of the illumination area 15 when a speckle pattern is vibrated, respectively. It is a figure showing distribution.

6A is a diagram showing two illuminance distributions of the illumination region 15 when illuminating the illumination region 15 with laser beams from two directions, and FIG. 6B is a diagram showing two illuminance distributions of FIG. 6A. It is a figure which shows the illumination distribution of a sum.

FIG. 7 is a diagram showing how a reticle scans a slit-shaped illumination area.

[Explanation of symbols]

 Reference Signs List 1 excimer laser light source 6, 7 fly-eye lens 8 vibrating mirror 15 illumination area 17 two-dimensional image sensor 18 image processing system R reticle PL projection optical system W wafer RST reticle stage WST wafer stage

Continuation of front page (56) References JP-A-1-235289 (JP, A) JP-A-1-259533 (JP, A) JP-A-1-257327 (JP, A) JP-A-4-250455 (JP) JP-A-4-252012 (JP, A) JP-A-6-267826 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/027 G03B 27/32 G03F 7/20 521

Claims (21)

(57) [Claims] 1. A light source for generating illumination light having spatial coherence , an illumination optical system for illuminating an illumination area of a predetermined shape with the illumination light, and a predetermined pattern formed relative to the illumination area. An exposure apparatus for scanning and exposing the substrate , the relative scanning unit scanning the mask and the substrate in synchronization with each other, wherein a direction in which the spatial coherence of the illumination light is high is relative to the illumination area of the predetermined shape and the mask An exposure apparatus characterized by having the same scanning direction. 2. The exposure apparatus according to claim 1, wherein the direction in which the spatial coherence of the illumination light is high is a direction in which the contrast of a speckle pattern formed in the illumination area is high. 3. The exposure apparatus according to claim 1, further comprising a displacement unit for displacing a speckle pattern of the illumination light formed in the illumination area in the illumination area. Wherein said displacing means, an exposure apparatus according to claim 3, characterized in that to displace the speckle pattern in the direction of the relative scanning. Wherein said displacing means, an exposure apparatus according to claim 3 or 4 further characterized in that to displace the speckle pattern in a direction intersecting the direction of the relative scanning. Wherein a direction intersecting the direction of the relative scanning,
The exposure apparatus according to claim 5, wherein the contrast of the speckle pattern is in a low direction. 7. The light source according to claim 3, wherein the light source is a pulse light source that emits the illumination light in a pulsed manner, and wherein the displacement means displaces the speckle pattern in synchronization with the pulse oscillation.
7. The exposure apparatus according to claim 6. 8. A pulse light source for generating pulse light having spatial coherence , an illumination optical system for illuminating an illumination area having a predetermined shape with the pulse light, and a predetermined pattern formed relative to the illumination area. Relative exposure means for scanning the mask and the substrate in synchronization with each other, and scanning and exposing the substrate , wherein the relative scanning speed of the illumination area of the predetermined shape and the mask A phase in which the phase of the speckle pattern of the pulse light in the illumination area is changed for each pulse light in accordance with a pitch of the speckle pattern of the pulse light in the illumination area in the relative scanning direction. An exposure apparatus comprising a variable unit. 9. A spatial coherence detecting means for detecting a spatial coherence of the pulse light, and a control means for controlling an operation of the phase varying means in accordance with the detected spatial coherence of the pulse light. The exposure apparatus according to claim 8, wherein: 10. A light source for generating illumination light having spatial coherence, an illumination optical system for illuminating an illumination area having a predetermined shape with the illumination light, and a predetermined pattern formed relative to the illumination area. An exposure apparatus for scanning and exposing the substrate, the relative scanning unit scanning the mask and the substrate in synchronization, wherein a speckle pattern of the illumination light formed in the illumination area is displaced in the illumination area. A displacement unit, wherein the displacement is performed such that the influence of a speckle pattern formed in the illumination area is reduced when the mask and the substrate are moving with respect to the illumination area during the scanning exposure. An exposure apparatus, comprising: control means for controlling means. 11. An exposure apparatus according to claim 10, wherein said control means controls said displacement means so that said speckle pattern is displaced in said relative scanning direction. 12. The method of claim 11, wherein the control means, in accordance with the relative scanning velocity between the said illumination region mask, the exposure apparatus according to claim 11, wherein the controller controls the displacement means. 13. An exposure apparatus according to claim 11, wherein said control means controls said displacement means in accordance with the illuminance distribution of said speckle pattern. 14. The apparatus according to claim 1 , wherein said control means controls said displacement means so that said speckle pattern is displaced in a direction intersecting with said relative scanning direction.
An exposure apparatus according to any one of 0 to 13. 15. The light source according to claim 10, wherein the light source is a pulse light source that emits the illumination light in a pulsed manner, and wherein the displacement means displaces the speckle pattern in synchronization with the pulse oscillation.
15. The exposure apparatus according to any one of claims 14 to 14. 16. The apparatus according to claim 16 , further comprising detecting means for detecting spatial coherence of said illumination light, wherein said control means controls said displacement means in accordance with the spatial coherence detected by said detecting means. The exposure apparatus according to any one of claims 10 to 15. 17. A light source for generating illumination light having spatial coherence, an illumination optical system for illuminating an illumination area having a predetermined shape with the illumination light, and a predetermined pattern formed relative to the illumination area. An exposure apparatus that has a relative scanning unit that scans a mask and a substrate in synchronization with each other, and that scans and exposes the substrate. A measuring unit that measures information on a divergence angle of the illumination light, and information on the measured divergence angle. Control means for controlling an exposure condition of the substrate based on the control information. 18. A light source for generating illumination light having spatial coherence, an illumination optical system for illuminating an illumination area having a predetermined shape with the illumination light, and a mask on which a predetermined pattern is formed relative to the illumination area. And an exposure apparatus for scanning and exposing the substrate, wherein the illumination optical system is configured to illuminate the illumination light from the light source with first illumination light of a first polarization component. A polarizing unit that separates the second illumination component into a second illumination light, wherein the first illumination light and the second illumination light have an illuminance distribution on the mask shifted from each other in the relative scanning direction. An exposure apparatus. 19. An illumination area having a predetermined shape is illuminated with illumination light having spatial coherence, and a mask and a substrate on which a predetermined pattern is formed relative to the illumination area are synchronously scanned. In the exposure method of scanning and exposing the substrate, the high-contrast direction of a speckle pattern formed in the illumination area may be the same as the relative scanning direction of the illumination area of the predetermined shape and the mask. Characteristic exposure method. 20. Illuminating an illumination area with illumination light having spatial coherence, and synchronously scanning a mask and a substrate on which a predetermined pattern is formed with respect to the illumination area, thereby scanning the substrate. In the exposure method of performing scanning exposure, the illumination light is emitted from a light source having a cross-sectional shape having a longitudinal direction and a lateral direction, and the lateral direction of the cross-sectional shape of the illumination light is a distance between the illumination region and the mask. An exposure method, wherein the exposure method coincides with a relative scanning direction. 21. An illumination area having a predetermined shape is illuminated with illumination light having spatial coherence, and a mask and a substrate on which a predetermined pattern is formed relative to the illumination area are synchronously scanned, whereby: In the exposure method of scanning and exposing the substrate, during the scanning exposure, when the mask and the substrate are moving with respect to the illumination area, the influence of a speckle pattern formed in the illumination area is small. An exposing method, wherein the speckle pattern is displaced within the illumination area so as to be as follows.