JP2884947B2 - Projection exposure apparatus, exposure method, and method of manufacturing semiconductor integrated circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type exposure apparatus used for forming fine patterns such as semiconductor integrated circuits and liquid crystal displays.

[0002]

2. Description of the Related Art A projection optical system used in a projection type exposure apparatus of this kind is incorporated into the apparatus through advanced optical design, careful selection of glass materials, ultra-precision processing of glass materials, and precise assembly adjustment. . At present, in a semiconductor manufacturing process, a reticle (mask) is used with i-line (wavelength 365 nm) of a mercury lamp as illumination light.
, And a stepper is mainly used in which a transmitted light of a circuit pattern on the reticle is imaged on a photosensitive substrate (a wafer or the like) via a projection optical system. An excimer stepper using an excimer laser (KrF laser having a wavelength of 248 nm) as illumination light is also used for evaluation or research. When the projection optical system for an excimer stepper is constituted by only a refraction lens, usable glass materials are limited to quartz, fluorite and the like.

Generally, in order to faithfully transfer a fine reticle pattern onto a photosensitive substrate by exposure using a projection optical system, the resolution and depth of focus (DOF) of the projection optical system are important factors. Has become.
Among projection optical systems currently in practical use, those having an aperture of about 0.6 for i-line have been obtained. When the wavelength of the illumination light to be used is the same, if the numerical aperture of the projection optical system is increased, the resolving power is correspondingly improved. However, the depth of focus (DOF) decreases with increasing numerical aperture NA. The depth of focus is defined by DOF = ± λ / NA ² where λ is the wavelength of the illumination light.

FIG. 1 schematically shows an image forming optical path of a conventional projection optical system.
A and a rear lens group GB. In general, this type of projection optical system has both the reticle R side and the wafer W side telecentric, or has only the wafer W side telecentric. In FIG. 1, three arbitrary points A, B, and C are assumed on the pattern surface of the reticle R (the object surface of the projection optical system). Light rays L ₁ , L ₂ , L ₃ , La, L traveling in various directions from point A
a ', of the La ", light L ₁ occurs at an angle that can not enter the lens system GA of the projection optical system. Moreover, of the light incident on the lens system GA of the front group, ray L _2, L ₃
Is a pupil e located on the Fourier transform plane FTP in the projection optical system.
cannot pass through p. And the other rays La, L
a ′ and La ″ pass through the pupil ep, enter the rear lens system GB, and converge on a point A ′ on the surface of the wafer W (pupil plane of the projection optical system). Of the light rays generated from A, the light rays that have passed through the pupil ep (a circular area centered on the optical axis AX) of the projection optical system contribute to forming a point image at the point A ′. The ray La passing through the center point CC (the position of the optical axis AX) of the pupil ep among the rays directed to the point A ′ is called a principal ray. Each space on the image plane side is parallel to the optical axis AX.

The same holds true for light rays generated from each of the other points B and C on the reticle R, and only light rays passing through the pupil ep contribute to the formation of point images B 'and C'. Similarly, the light beams Lb and Lc that travel from each of the points B and C in parallel with the optical axis AX and enter the lens system GA are both principal light beams that pass through the center point CC of the pupil ep. As described above, the pupil ep has a Fourier transform and an inverse Fourier transform relationship with respect to the pattern surface of the reticle R and the surface of the wafer W, respectively. All the pupils ep are superimposed and passed.

The numerical aperture of such a projection optical system is generally expressed as a value on the wafer side. In FIG. 1, among the light beams contributing to the formation of the point image A ′, the angle θw formed by the light beams La ′ and La ″ passing through the outermost part in the pupil ep and the principal light beam La on the wafer W is determined by the projection optical system. Corresponds to the numerical aperture NA _W on the wafer (image plane) side, and is expressed by NAw = sin θw. Therefore, the angle θr formed by the rays La ′ and La ″ with the principal ray La on the reticle R side is determined by the reticle (object plane) ) Side is referred to as a numerical aperture NAr, and is represented by NAr = sin θr. Further, the imaging magnification of the projection optical system is set to M (in the case of 1/5 reduction, M
= 0.2), there is a relationship of NAr = M · NAw.

In order to increase the resolution, the numerical aperture NAw (NAr) is increased. In other words, the diameter of the pupil ep must be increased, and the effective diameters of the lens systems GA and GB must be increased. There is no other way to make it bigger.
However, the depth of focus DOF decreases in inverse proportion to the square of the numerical aperture NAw, so that even if a projection optical system having a high numerical aperture can be manufactured, the required depth of focus cannot be obtained. This is a major obstacle in practical use.

When the wavelength of the illumination light is 365 nm of the i-line and the numerical aperture NAw is 0.6, the depth of focus DOF is about 1 μm (± 0.5 μm) in width, and one shot on the wafer W In a region (about 20 mm square to 30 mm square), a portion having a surface irregularity or curvature equal to or larger than DOF causes poor resolution. Also on the stepper system, focus adjustment for each shot area of the wafer W,
It becomes necessary to perform leveling and the like with extremely high accuracy, and the burden on the mechanical system, the electric system, and the software (improvement in measurement resolution, servo control accuracy, setting time, and the like) increases.

Therefore, the present applicant has solved the problems of the projection optical system, and has a high resolution and a large focus without using a phase shift reticle as disclosed in Japanese Patent Publication No. 62-50811. A new projection exposure technique that can obtain both the depth and
No. 148, Japanese Patent Application Laid-Open No. 4-225358, and the like. This exposure technique increases the apparent resolving power and depth of focus by controlling the illumination method for the reticle to a special shape while maintaining the existing projection optical system.
HRINC (S uper H igh R esoluti
on by I llumi N ation C ontro
l) It is called the law. In the SHRINC method, two illumination lights (or four illumination lights) symmetrically inclined in a pitch direction of a line-and-space pattern (L & S pattern) on a reticle R are irradiated on the reticle, and are generated from the L & S pattern. One of the 0th-order diffracted light component and one of the ± 1st-order diffracted light components passes symmetrically with respect to the center point CC in the pupil ep of the projection optical system. The projection image (interference fringe) of the L & S pattern is generated using the principle.

As described above, according to the image formation utilizing the two-beam interference, the generation of the wavefront aberration at the time of defocus is suppressed as compared with the case of the conventional method (normal vertical illumination), so that the apparent depth of focus becomes large. It is. However, according to the SHRINC method, an intended effect can be obtained when the pattern formed on the reticle R has a periodic structure like an L & S pattern (lattice). Does not have that effect.
In general, in the case of an isolated micropattern, the diffracted light from the micropattern is generated almost as a Fraunhofer diffraction, so that the 0th-order diffracted light and the higher-order diffracted light are not clearly separated in the pupil ep of the projection optical system.

Therefore, as an exposure method for increasing the apparent depth of focus for an isolated pattern such as a contact hole, exposure to one shot area of the wafer W is divided into a plurality of times, and the wafer W A method of moving the lens by a certain amount in the direction has been proposed, for example, in Japanese Patent Application Laid-Open No. 63-42122. This exposure method FLEX (F ocu
s L attitude enhancement EX
This method is called a “posture” method, and a sufficient effect of increasing the depth of focus can be obtained for isolated patterns such as contact holes. However, since the FLEX method requires multiple exposures of a slightly defocused contact hole image, the resist image obtained after development necessarily has a reduced sharpness. The problem of the decrease in sharpness (deterioration of profile) is that a resist having a high gamma value is used,
Use a multilayer resist, or use CEL (Contr
This can be compensated for by using a first enhancement layer.

As an attempt to increase the depth of focus at the time of projecting a contact hole pattern without moving the wafer W in the optical axis direction during the exposure operation as in the FLEX method, 1
Proceedings 29a-ZC-8 of the Japan Society of Applied Physics Spring, 991,
The Super-FLEX method published in No. 9 is also known. This Super FLEX method uses a pupil e of the projection optical system.
A transparent phase plate is provided on p, and a characteristic is provided such that the complex amplitude transmittance given to the imaging light by this phase plate sequentially changes from the optical axis AX toward the periphery. In this way, the image formed by the projection optical system is kept sharp at a constant width (wider than the conventional one) in the optical axis direction around the best focus plane (a plane conjugate with the reticle R). This increases the depth of focus.

[0013]

Among the various conventional techniques described above, the FLEX method and the Super FLEX method can obtain a sufficient effect of increasing the depth of focus for an isolated contact hole pattern. However, it has been found that, with a plurality of contact hole patterns which are close to each other, unnecessary film loss occurs in the photoresist between the holes in both methods, which makes it practically difficult to use.

Further, in the FLEX method, even with an isolated contact hole pattern, the sharpness of the image (composite optical image obtained by multiple exposure) is necessarily deteriorated. There is also a problem that the degree decreases. Further, it is difficult to apply the FLEX method in which the wafer is continuously moved or vibrated in the optical axis direction during the exposure operation to a scanning exposure type exposure apparatus, and the exposure is divided into a first exposure and a second exposure. In the method in which the wafer is moved in the optical axis direction between each exposure, there is a problem that the processing capacity is greatly reduced and the throughput is significantly reduced.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a projection exposure apparatus with an increased depth of focus when projecting an isolated pattern such as a contact hole. It is an object of the present invention to obtain a device capable of obtaining an effect of increasing the depth of focus.

[0016]

According to the present invention, there is provided a projection exposure apparatus which illuminates a mask on which a pattern is formed and guides light from the pattern onto a substrate. There is provided a conversion means provided between the substrate and the substrate, the conversion means being configured to convert light from the pattern into a plurality of lights with reduced interference with each other.

[0017]

The operation of the present invention will be described based on the description of the embodiment. A plane in the projection optical system (hereinafter abbreviated as a pupil plane) that optically has a Fourier transform relationship with respect to the reticle pattern plane;
Or, a polarization state control member is provided on a surface in the vicinity thereof, and a part of the imaging light distributed in a circular or annular shape in the pupil plane and the imaging light distributed in other parts do not interfere with each other. State. As a result, the exposure luminous flux (imaging light) transmitted and diffracted in the reticle pattern, especially through the contact hole pattern, is spatially divided into two luminous fluxes that do not interfere with each other in the pupil plane, and reaches the object to be exposed such as a wafer. I do. Since the two light beams do not interfere with each other even on the wafer (they are incoherent), an intensity-combined image in terms of the light amount of the image (the image of the contact hole) created by each light beam is obtained. In the conventional exposure method, the light flux transmitted and diffracted through the minute contact hole pattern on the reticle reaches the wafer surface via the projection optical system, where it is all amplitude-combined (coherent addition), and the image of the reticle pattern (optical image) ) Was formed. Even in the conventional Super-FLEX method, the imaging light distributed on the pupil plane is only partially phase-shifted, so that it is still coherent addition.

Assuming that there is no phase shift plate or the like on the pupil plane of the projection optical system, the optical path length from any one point on the reticle to the corresponding image point on the wafer in the best focus (focused state). Are the same regardless of which optical path in the projection optical system they pass through (Felmer's principle), so that the amplitude synthesis on the wafer becomes a light synthesis without a phase difference,
All work in the direction of increasing the strength of the contact hole pattern.

However, when the wafer is defocused, the above optical path length differs depending on the optical path in the projection optical system. As a result, the above-described amplitude synthesis is performed by the optical path difference (phase difference).
Is added, and a canceling effect is generated partially, thereby weakening the center intensity of the contact hole pattern.
The optical path difference generated at this time is as follows, where θ is an incident angle of an arbitrary ray incident on one image point on the wafer, and the optical path length of a ray (principal ray) incident perpendicularly on the wafer is a reference (= 0). It is approximately expressed as （(ΔF · sin ² θ). Here, ΔF represents the defocus amount. Since the maximum value of sin θ is the numerical aperture NAw on the wafer side of the projection optical system, the maximum value when all the lights that have passed through the pupil ep among the diffracted lights from the minute hole pattern are amplitude-combined on the wafer as in the related art. Causes an optical path difference of 1/2 (ΔF · NAw ² ). At this time, assuming that an optical path difference of λ / 4 is allowed as the depth of focus, the following relationship is established.

1/2 (ΔF · NAw ² ) = λ / 4 When this expression is re-arranged, ΔF = λ / (2NAw ² ), which is equivalent to the commonly known depth of focus. For example, i-line (wavelength 0.3
65 μm) and the numerical aperture NAw = 0.50
Is assumed, the depth of focus ± ΔF / 2 is ± 0.73 μm, which is a value with little allowance for a process step difference of about 1 μm on the wafer.

On the other hand, in the present invention, as shown in FIG. 2, a polarization state control member PCM is provided on a pupil plane (FTP) of the projection optical system. At this time, the imaging light flux diffracted by the isolated pattern Pr formed on the pattern surface of the reticle R (the principal ray is LL
p) enters the front lens system GA of the projection optical system PL and then reaches the Fourier transform plane FTP. Then, on the Fourier transform plane FTP, the light beams transmitted through the circular transmission part FA and the annular transmission part FB at the center in the pupil plane ep are controlled (converted) to a polarization state in which they do not interfere with each other. Therefore, on the wafer W, the light beam LFa transmitted through the circular transmission portion FA of the polarization control member PCM and the light beam LFb transmitted through the surrounding transmission portion FB do not cause interference. As a result, the light beam LFa from the circular transmitting portion FA and the peripheral portion FB
LFb from each other independently interfere with each other only by themselves, and each image (intensity distribution) P of the hole pattern
forming r ′. That is, an image generated on the wafer W by interference of only the light beam LFa and an image generated by interference of only the light beam LFb are simply added in terms of intensity to obtain an isolated image such as a contact hole obtained by the present invention. An image Pr 'of the pattern is obtained.

The illuminating light ILB for the reticle R has a constant numerical aperture sinψ / 2 as in the prior art. However, for the numerical aperture NAr on the reticle side of the projection optical system PL, the condition of NAr> sinψ / 2 is set. Therefore, the principle of image formation according to the present invention will be further described with reference to FIG. FIG. 3 schematically shows the relationship between the structure of the polarization state controlling member PCM, the state of an imaged light beam that generates an image Pr ′ of the contact hole, and the optical path difference ΔZ of each light beam during defocusing. is there.

A light beam LFa passing through the center as shown in FIG.
Since the light beam LFa includes the angle range from the vertically incident light (principal ray LLp) to the incident angle θ ₁ in the amplitude synthesis within
The maximum value ΔZ ₁ of the optical path difference when the defocus amount is ΔF is Δ
Z ₁ = １ ／ (ΔF · sin ² θ ₁ ). FIG.
The horizontal axis of the graph at the bottom of represents the sine of the incident angle, and sin
θ ₁ = NA ₁ . On the other hand, the amplitude synthesis in light flux LFb through the peripheral portion as shown in FIG. 3 (B), the light flux LFb has an incident angle range of the incident angle theta ₁ to the numerical aperture NAw (sinθw), the defocus amount is ΔF Is the maximum optical path length difference ΔZ ₂ , ΔZ ₂ = １ ／ (ΔF) (NAw ²
−sin ² θ ₁ ).

Since the first light beam LFa and the second light beam LFb do not interfere with each other, the deterioration of the image Pr ′ ₁ due to the interference of the light beam LFa alone and the deterioration of the image Pr ′ ₂ due to the interference of the light beam LFb alone are This is due to only the optical path length differences ΔZ ₁ and ΔZ ₂ in the light beam. For example, sin θ ₁ is set so that sin ² θ ₁ = １ ／ (NAw ² ), that is,

[0025]

(Equation 1)

The first transmitting portion F is set to substantially satisfy the relationship
When the radius of A is set, the maximum optical path difference ΔZ ₁ due to the first light beam LFa and the maximum optical path difference ΔZ due to the second light beam LFb
₂ is as follows. ΔZ ₁ = １ ／ (ΔF · sin ² θ ₁ ) = １ ／ (ΔF · NAw ² ) ΔZ ₂ = １ ／ (ΔF) (NAw ² −sin ² θ ₁ ) = １ ／ (ΔF · NAw ² ) Thus, two incoherent light beams LFa, L
Each of Fb has substantially the same maximum optical path difference, 1/4 (ΔF · NAw ² ) at the time of defocusing of ΔF, and this value is half that of the conventional case. In other words, even if the defocus amount is twice as large as the conventional one (2ΔF), the same maximum optical path length difference as in the case of the defocus amount ΔF in the conventional projection method is sufficient, and as a result, the isolated pattern Pr
Will be approximately doubled during imaging. The pupil plane ep of the projection optical system PL, a method of exchanging a plurality of light beams do not interfere with imaging light beam from each other, thereafter SFINCS (S patial F ilter for
It will be referred to as INC oherent S tream) method.

[0027]

FIG. 4 shows the overall configuration of a projection exposure apparatus according to an embodiment of the present invention. In FIG. 4, high-luminance light emitted from a mercury lamp 1 is converged to a second focal point by an elliptical mirror 2, and then becomes divergent light and enters a collimator lens 4. A rotary shutter 3 is disposed at the position of the second focal point, and controls passage and cutoff of illumination light. The illumination light converted into a substantially parallel light beam by the collimator lens 4 is
The light enters the interference filter 5 where only the desired spectrum required for exposure, for example, i-line, is extracted. The illumination light (i-line) emitted from the interference filter 5 passes through a polarization control member 6 for aligning the polarization direction, and then enters a fly-eye lens 7 as an optical integrator.
This polarization control member 6 may be omitted depending on the configuration of the polarization state control member PCM in the projection optical system PL and the nature of the light source, which will be described later. The polarization control member 6
Since only the illumination light incident on the fly-eye lens 7 is aligned in a certain polarization direction, a polarizing plate may be used.

The illumination light (substantially parallel light beam) incident on the fly-eye lens 7 is divided by a plurality of lens elements of the fly-eye lens 7, and a secondary light source image (mercury) is provided on each exit side of each lens element. An image of the light emitting point of the lamp 1) is formed. Therefore, the same number of point light source images as the number of lens elements are distributed on the exit side of the fly-eye lens 7, and a surface light source image is created. On the exit side of the fly-eye lens 7, a variable stop 8 for adjusting the size of the surface light source image is provided. Illumination light (divergent light) passing through the stop 8 is reflected by a mirror 9 and enters a condenser lens system 10 to irradiate a rectangular opening of the reticle blind 11 with a uniform illuminance distribution. 4, among the plurality of secondary light source images (point light sources) formed on the exit side of the fly-eye lens 7, the optical axis A
Only the illumination light from one secondary light source image located on X is representatively shown. Also, by the condenser lens system 10,
The exit side (the surface on which the secondary light source image is formed) of the fly-eye lens 7 is a Fourier transform surface with respect to the rectangular opening surface of the reticle blind 11. Therefore, fly-eye lens 7
From each of the plurality of secondary light source images
The illumination lights incident on 0 are superimposed on the reticle blind 11 as parallel light beams having slightly different incident angles from each other.

The illumination light passing through the rectangular opening of the reticle blind 11 enters the condenser lens 14 via the lens system 12 and the mirror 13, and the light emitted from the condenser lens 14 reaches the reticle R as illumination light ILB. Here, the rectangular opening surface of the reticle blind 11 and the pattern surface of the reticle R are conjugated to each other by a combined system of the lens system 12 and the condenser lens 14,
The image of the rectangular opening of the reticle blind 11 is the reticle R
The image is formed so as to include a rectangular pattern formation region formed in the pattern plane of FIG. As shown in FIG. 4, the illumination light ILB from one secondary light source image located on the optical axis AX among the secondary light source images of the fly-eye lens 7 has a tilt with respect to the optical axis AX on the reticle R. There is no parallel light flux,
This is because the reticle side of the projection optical system PL is telecentric. Of course, a large number of secondary light source images (off-axis point light sources) that are offset from the optical axis AX are formed on the exit side of the fly-eye lens 7, and any illumination light from these secondary light source images is on the reticle R. In this case, a parallel light beam inclined with respect to the optical axis AX is superimposed in the pattern formation region.
It goes without saying that the pattern surface of the reticle R and the exit side surface of the fly-eye lens 7 are optically Fourier-transformed by the combined system of the condenser lens system 10, the lens system 12, and the condenser lens 14. . Also, the incident angle range of the illumination light ILB on the reticle R (see FIG. 2)
Varies depending on the aperture diameter of the stop 8, and when the aperture diameter of the stop 8 is reduced to reduce the substantial area of the surface light source, the incident angle range な る also decreases. Therefore, the aperture 8 adjusts the spatial coherency of the illumination light. As a factor representing the degree of the spatial coherency, a ratio (σ value) between the sine of the maximum incident angle ψ / 2 of the illumination light ILB and the numerical aperture NAr on the reticle side of the projection optical system PL is used. This σ value is usually defined as σ = sin (ψ / 2) / NAr, and most steppers currently in operation have σ = 0.
It is used in the range of about 5 to 0.7.

A predetermined reticle pattern is formed on the pattern surface of the reticle R by a chromium layer. Here, a chromium layer is vapor-deposited on the entire surface, and a fine rectangular opening (transparent without a chrome layer) is formed therein. It is assumed that there are a plurality of contact hole patterns formed in section (1).
The contact hole pattern may be designed to have a dimension of 0.5 μm square (or diameter) or less when projected onto the wafer W.
In consideration of the above, the size on the reticle R is determined. In addition, since the dimension between the contact hole patterns adjacent to each other is usually much larger than the dimension of the opening of one contact hole pattern, it exists as an isolated minute pattern. That is, two adjacent contact hole patterns are often separated to such an extent that light (diffraction, scattered light) generated from each does not strongly influence each other unlike a diffraction grating. However, as will be described in detail later, there is also a reticle in which a contact hole pattern is formed in a very close arrangement.

In FIG. 4, reticle R is held on reticle stage RST, and an optical image (light intensity distribution) of a contact hole pattern of reticle R is formed on a photoresist layer on the surface of wafer W via projection optical system PL. Is done.
Here, the optical path from the reticle R to the wafer W in FIG. 4 is indicated only by the principal ray of the imaging light beam. And the projection optical system P
The polarization state control member PCM described with reference to FIGS. 2 and 3 is provided on the Fourier transform plane FTP in L. The polarization state control member PCM has a diameter that covers the maximum diameter of the pupil ep, and can be moved out of the optical path or enter the optical path by the slider mechanism 20. If the stepper is used exclusively for exposing a contact hole pattern, the polarization control member PCM
May be fixed in the projection optical system PL. However, in the case where the exposure operation of the lithography process is performed by a plurality of steppers, in consideration of the most efficient operation of each stepper, it is hesitant to assign a specific one stepper to the exposure dedicated to the contact hole pattern. Therefore, the polarization state control member PCM is connected to the projection optical system P.
It is desirable that the stepper can be used so that it can be inserted into and removed from the L pupil ep, even when exposing a reticle pattern other than the contact hole pattern. still,
Depending on the projection optical system, the pupil position (Fourier transform plane F
TP) may be provided with a circular aperture stop for changing the effective pupil diameter. In this case, the aperture stop and the polarization state control member PCM are arranged so as not to mechanically interfere with each other and as close as possible.

The wafer W moves two-dimensionally (hereinafter referred to as XY movement) in a plane perpendicular to the optical axis AX.
It is held on wafer stage WST that slightly moves (hereinafter, referred to as Z movement) in a direction parallel to optical axis AX. The XY movement and the Z movement of the wafer stage WST are performed by the stage drive unit 22. The XY movement is controlled according to the coordinate measurement value by the laser interferometer 23, and the Z movement is based on the detection value of the auto-focusing focus sensor 24. It is controlled based on. Stage drive unit 2
2. The slider mechanism 20 and the like operate according to a command from the main control unit 25. The main control unit 25 further sends a command to the shutter drive unit 26,
Of the aperture 8 and the size of each aperture of the aperture 8 or the reticle blind 11 are controlled. Further, the main control unit 25 can input a reticle name read by a bar code reader 28 provided in a reticle transport path to the reticle stage RST. Therefore, the main control unit 2
5 is a slider mechanism 20 according to the input reticle name.
, The operation of the aperture driving unit 27, and the like, and automatically adjusts the aperture size of the aperture 8, the reticle blind 11, and the necessity / unnecessity of the polarization state control member PCM according to the reticle. be able to.

Here, the structure of a part of the projection optical system PL in FIG. 4 will be described with reference to FIG. Figure 5 shows a partial cross section of the projection optical system PL made in all refractive glass material, the top of the lens GB ₁ lens system GB at the bottom of the lens GA ₁ and the rear group lens system GA of the front lens group A Fourier transform plane FTP exists in the space between. Although the projection optical system PL holds a plurality of lenses in a lens barrel, the polarization state control member P
An opening is provided in a part of the lens barrel for inserting and removing the CM. In addition, a cover 20B that does not directly expose all or a part of the polarization state control member PCM and the slider mechanism 20 to the outside air is extended from the opening of the lens barrel. This cover 2
0B prevents minute dust floating in the outside air from entering the pupil space of the projection optical system PL. The slider mechanism 20 is coupled to an actuator 20A such as a rotary motor, a pen cylinder, and a solenoid. Further, a flow path Af communicating with the pupil space is provided in a part of the lens barrel, and clean air whose temperature is controlled is supplied to the pupil space via the pipe 29, so that a part of the exposure light of the polarization state control member PCM is provided. The temperature rise due to absorption and the temperature rise in the entire pupil space are suppressed. Incidentally, if the clean air forcedly supplied to the pupil space is forcibly discharged through the slider mechanism 20 and the actuator 20A, the slider mechanism 20
And the like can be prevented from entering the pupil space.

FIG. 6 shows the structure of the polarization state controlling member PCM according to the first embodiment, and FIG.
(B) is a plan view. As described above with reference to FIG. 3, the radius r _{1 of the} circular transmission portion FA that gives the first polarization state.
Is the effective maximum radius r ₂ of the pupil ep,

[0035]

(Equation 2)

In practice, it is better to be larger by about several percent. The As is apparent from the equation, the area pi] r ₁ ² of circular transmitting portion FA is made about a half of the area pi] r ₂ ² the effective pupil aperture. The light source (the mercury lamp 1) in FIG. 4 generates light in a random polarization state (light that is a combination of light in various polarization states and the polarization state changes with time). In the first embodiment of the present invention, since a linear polarizing plate is used as the polarization state control member PCM in FIG. 6, the polarization control member 6 in FIG. 4 is omitted. In this case, the polarization state of the light beam that passes through the contact hole pattern on the reticle and reaches the polarization state control member PCM is also random. The polarization state control member PCM shown in FIG. 6 is configured by a polarizing plate that transmits only linearly polarized light in a specific direction in a circular transmission portion FA having a radius r ₁ from the center point CC, and has a ring-shaped periphery coaxial with the center point CC. The transmitting portion FB is formed of a polarizing plate that transmits only linearly polarized light in a direction orthogonal to the circular transmitting portion FA. Accordingly, the polarization state of the image forming light beam after passing through the polarization state control member PCM in FIG.
As shown in (c), in the central transmission part FA, for example, it becomes a vibration plane (polarization plane) of the electric field from the upper right to the upper left in the same figure, and in the peripheral transmission part FB, it becomes a polarization plane from the upper left to the lower right, and is orthogonal to each other. And the light beams (LFa, LFb) do not interfere with each other. Both the central and peripheral light beams that do not interfere with each other are
, The amplitude of each is synthesized only with itself, and the images (intensity distribution) Pr ₁ ′ and Pr ₂ ′ are separately formed, and the principle of increasing the depth of focus of the synthesized image (composite intensity distribution) As described in the section.

FIG. 7 shows a structure of a polarization state controlling member PCM according to a second embodiment. In this embodiment, as in FIG. 6, the central circular transmission part FA and the peripheral annular transmission part FB are completely the same in that they are polarizers that pass only linearly polarized light in polarization directions orthogonal to each other. The difference is that a quarter-wave plate FC is further provided on the entire surface on the emission side. The axial direction of the quarter-wave plate FC (the direction in which the refractive index of the crystal is high with respect to the incident light beam) is the opposite of the linearly polarized light transmitted through the circular transmission portion FA and the linearly polarized light transmitted through the annular transmission portion FB. (Left ・
Right) Axial direction for exchange to circularly polarized light. Where 1 /
The wavelength of the four-wavelength plate FC is, of course, the wavelength λ of the exposure light. The material of the quarter wave plate FC is a birefringent material such as quartz. Now, the polarization state of the image forming light beam transmitted through the polarization state control member PCM shown in FIGS.
As shown in (C), for example, clockwise circularly polarized light is formed in the transmission part FA, and counterclockwise circularly polarized light is formed in the peripheral transmission part FB. Naturally, this circular polarization state determines the rotation direction of the quarter-wave plate FC and the polarizing plates FA and FB such that the transmitted light of the central transmitting portion FA is counterclockwise and the transmitted light of the peripheral transmitting portion FB is clockwise. You may.

In the first and second embodiments, since the polarization state control member PCM in the projection optical system PL is constituted by a polarizing plate, half of the original light amount to be transmitted through the projection optical system PL. Is absorbed by the polarizing plate as the polarization state controlling member PCM. This means a decrease in exposure power, but heat (energy of absorbed exposure light) is accumulated in the projection optical system, which is a problem in terms of stability of the optical system and the glass material.

An embodiment for solving the problem of heat (loss of exposure power) will be described with reference to FIGS. 8, 9, 10, 11, and 12. FIG. In the present embodiment, since the polarization characteristics of the illumination light ILB are important, the description will be given first. FIG. 8 shows some embodiments of the polarization control member 6 provided in the illumination optical system. FIG. 8A shows an example in which a polarizing plate 6A is used as the polarization control member 6, and the incident light from the mercury lamp 1, which is randomly polarized light, is emitted as specific linearly polarized light. FIG. 8B shows an example in which a polarization plate 6A and a quarter-wave plate 6B are combined as the polarization control member 6.
Also at this time, the incident light that is the randomly polarized light is polarized by the polarizing plate 6A.
The light is first converted into linearly polarized light, and then emitted by the quarter-wave plate 6B as either clockwise or counterclockwise circularly polarized light. Also at this time, the axial direction of the quarter-wave plate 6B is set to the axial direction for converting linearly polarized light from the polarizing plate 6A to circularly polarized light. Also, the light flux (incident light flux) itself from the light source is
In the case of linearly polarized light, for example, when a laser light source is used, the illumination light ILB reaching the reticle R is polarized light control member 6
Is linearly polarized light without being provided. However,
Depending on the configuration of the polarization state control member in the projection optical system described later, only the quarter-wave plate 6B may be provided as the polarization control member 6 as shown in FIG. The axial direction of the quarter-wave plate 6B in this case is also set as described above.

When the polarization characteristics of the illumination light ILB to the reticle R are made uniform by using the polarization control member 6 as shown in FIG. 8, the light passes through and diffracts through the contact hole pattern to form the projection optical system PL. The imaging light flux reaching the polarization state controlling member PCM in the middle is also in a state of being aligned with a specific linearly polarized light or circularly polarized light. Therefore, a structure of a polarization state control member PCM suitable for a case where the illumination light ILB is aligned with linearly polarized light is shown in FIG. 9 as a third embodiment. FIG. 9A shows an example in which a half-wave plate is used as the polarization state control member PCM. FIG.
(A) shows the polarization state of the light immediately before it enters the polarization state control member PCM. Here, it is assumed that the light is linearly polarized light having a vibration plane of the electric field in the vertical direction in FIG. Figure 9 (B) shows the plane structure of the polarized state control member PCM, circular transmitting portion FA ₁ of radius r ₁ is constituted by a half-wave plate, annular transmitting portion FA ₂ near the transmissive portion FA ₁ ( This is a normal transparent plate (for example, quartz) having a thickness (optical thickness) substantially equal to that of a (波長 wavelength plate). The polarization state of the light immediately after passing through the polarization state control member PCM of Figure 9 is partial polarization state of the circular transmitting portion FA ₁ as shown in FIG. 9 (C) is converted into the left-right direction of the linearly polarized light, around the ring polarization state in the portion of the strip transmitting portion FA ₂ is not changed at. For this reason, as in the first embodiment, it is possible to obtain a polarization state in which the central portion and the peripheral portion of the imaging light flux do not interfere with each other. Here, the transmission part FA
The axial direction (in-plane rotation) of the half-wave plate as ₁ is set to an axial direction that converts the direction of the incident linearly polarized light into a direction orthogonal thereto, but the axial direction of the half-wave plate is The polarization state control member PCM and the polarization control member 6 may be relatively adjustable in the plane in the rotational direction so as to optimize the polarization direction of the illumination light ILB.

On the other hand, FIG. 10B shows the polarization control member P
Radius r as CM₁Circular transmission part FA_TwoAnd surrounding zones
Shape transmission part FB_TwoBoth are composed of a quarter-wave plate (same thickness)
This is the fourth embodiment. Also in this case, the incident light beam is
Since all of the light are linearly polarized as shown in FIG.
_Two, FB_TwoThe axial direction of the 1/4 wavelength plate is
By optimizing for the state, it is shown in FIG.
Circular transmission part FA _TwoThe luminous flux passing through the
Light, annular transmission part FB_TwoIs a counterclockwise circle
Can be converted to polarized light, and have different polarization states (interference
No) light flux (LFa, LFb) can be obtained. This
Also in the case of the fourth embodiment, the polarization state is the same as in the third embodiment.
Along the axial direction of the 1/4 wavelength plate as the state control member PCM
Then, the polarization direction of the illumination light ILB is changed by the polarization control member 6.
It is good to be able to adjust. Note that, as shown in FIG.
Circular transmission part FA₁Half-wave plate as quartz, etc.
Optical rotation material may be used.
The direction of linearly polarized light can be changed.

FIG. 11 shows an example of the circularly polarized illumination light ILB.
To show a preferable configuration of the polarization state controlling member PCM.
This is an example. The fifth embodiment is basically similar to the first embodiment.
The same as the polarization state controlling member PCM of the third embodiment (FIG. 9)
Use Therefore, as shown in FIG.
₁Is composed of a half-wave plate and the circular polarization state of transmitted light
Can be reversed as shown in FIG. Week
Ring-shaped transmission part FB on the side ₁Is the transmission part FA₁1/2 wavelength plate
This is a transparent object (a quartz plate or the like) having the same thickness as that of the transparent object. The figure
In the case of 11 (B), as in the case of FIG.
Transmission part FB₁May be constituted by a half-wave plate.

FIG. 12 shows a configuration of a polarization state control member PCM according to a sixth embodiment suitable for circularly polarized illumination light ILB, which may be exactly the same as that of FIG.
That is, the circular transmitting portion FA ₂ and the annular transmission portion FB ₂ are each formed of a 波長 wavelength plate, and the axial directions of the ４ wavelength plates are adjusted and combined so as to be orthogonal to each other.
In the case of FIG. 12, the transmitted lights of the transmission parts FA ₂ and FB ₂ are linearly polarized light orthogonal to each other as shown in FIG.

As described above, if the incident light beam (illumination light ILB) is circularly polarized as shown in FIGS.
This is advantageous because there is no need to adjust the rotation of the 波長 wavelength plate in the axial direction in accordance with the polarization characteristics of the illumination light. As described above, when the polarization control member 6 shown in FIG. 8 and the polarization state control member PCM shown in each of FIGS. 9 to 12 are used, the absorption of exposure energy by the polarization state control member PCM as described above is performed. This is extremely advantageous in that the problem described above is eliminated and the heat accumulation in the projection optical system PL is suppressed. However, this time, the light amount loss (more than half) caused by aligning the illumination light ILB into one polarization state in the illumination optical system remains as a problem. Accordingly, an example of an illumination system in which the light amount loss of illumination light is reduced will be described as a seventh embodiment with reference to FIG. The system shown in FIG. 13 is provided instead of the polarization control member 6 shown in FIG. First, in FIG. 13A, an incident light beam is split by two polarizing beam splitters 6C and 6D.
Synthesized. That is, in the first polarization beam splitter 6C, the P-polarized light (vertical polarized light) component is transmitted and
The polarization beam splitter 6D is also transmitted and goes straight. On the other hand, the S-polarized light (polarized light in the direction perpendicular to the paper surface) split by the beam splitter 6C is combined by the beam splitter 6D via mirrors 6E and 6F, and travels coaxially with the P-polarized light component. At this time, an optical path difference of 2 × d ₁ is given to the P-polarized light and the S-polarized light by the optical paths of the mirrors 6E and 6F. Therefore, the temporal coherent length ΔLc of the incident light beam is 2
If it is shorter than d ₁ , the P-polarized light component and the S-polarized light component after the combination become incoherent (non-coherent) temporally in addition to the fact that the polarization directions are complementary. The illumination light having these two polarization components is used, and the polarization state control member PCM is used.
As shown in FIG. 14, when incident on the polarization state controlling member PCM, the P-polarized light component (for example, the direction of the white arrow) and the S-polarized light component (for example, the black arrow direction) are respectively shown in FIG. After passing through the polarization state controlling member PCM as shown in FIG. 14 (C), there are four light beams which do not interfere with each other. That is, the original polarization direction is rotated by 90 ° in the circular transmission portion FA ₁ (（wavelength plate). The four light beams have different polarization directions, and do not interfere with each other even if the polarization direction is the same in each of the transmission portions FA ₁ and FB ₁ because they are temporally incoherent. That, S-polarized light component that has passed through the transmitting portion FA ₁ is converted into P-polarized component, it becomes a P-polarized component transmitted through the transmitting portion FB ₁ and the same polarization direction, the two light that is temporally incoherent So do not interfere. If Figure 1
If the illumination light from the polarization control member having the configuration shown in FIG. 3 (A) is not used, the P-polarized light and the S-polarized light in FIG. 14 remain coherent in time. If the light beams have the same polarization direction, they will interfere with each other, and the effect of the present invention is diminished. FIG.
The system shown in (A) can make a large difference in the optical path length between two polarized components to be combined, so that it is suitable for a light source having a relatively long temporal coherence length, for example, a narrow band laser light source.

When the linearly polarized light is used as the laser light source, the effect of the present invention can be obtained without using the polarization control means having the configuration shown in FIG. However, if a polarization control means as shown in FIG. 13A is used for a linearly polarized laser light source, the illumination light can be made into two temporally incoherent light fluxes, which causes a problem when using the laser light source. Speckles and interference fringes (illuminance unevenness)
This has the effect that it can be reduced. in this case,
The polarization direction of the linearly polarized light incident on the first stage beam splitter 6C in FIG.
For C, as shown in FIG.
Polarization direction L intermediate to polarization direction (45 ° direction from both directions)
PL may be used.

When the light source is a light source having a relatively large spectral width such as a mercury lamp, its temporal coherence length is short. Therefore, a simple member as shown in FIG. It can be used as the control member 6. This member is a transparent parallel plate 6G made of quartz or the like with a polarizing reflection film 6H attached to the surface and a total reflection film 6J made of metal or the like attached to the back surface so as to reflect a collimated light beam from a mercury lamp at a predetermined angle. Placed in At this time, of the randomly polarized incident light from the mercury lamp, the S-polarized component (the direction perpendicular to the paper) is reflected by the surface film 6H,
The polarized light component passes through the film 6H on the front surface and the parallel plate 6G and is reflected by the film 6J on the back surface. The S-polarized light component and the P-polarized light component are almost twice the thickness (optical thickness) of the substantially parallel plate 6G. Is provided.

For example, in the case of an i-line from a mercury lamp, the center wavelength λ is 365 nm and the wavelength width Δλ is about 5 nm.
Commonly used coherent length equation, ΔLc = λ ² / Δ
From λ, the coherent length ΔLc is about 26 μm.
Therefore, a sufficiently thin parallel plate 6G (for example, about 1 mm thick)
However, it is possible to provide a sufficient optical path length difference to eliminate temporal coherence.

Next, FIG. 13A or FIG.
(B) Polarization control means and polarization state control member PCM in FIG.
An eighth embodiment combining the above will be described with reference to FIG. In this embodiment, a ４ wavelength plate is provided on the exit side of the system shown in FIG.
As shown in (A), the light is converted into circularly polarized light having directions opposite to each other. At this time, the light beam transmitted through the polarization state controlling member PCM is as shown in FIG. 15C, and is similarly four light beams that do not interfere with each other. Figure 15, for example, in the polarized light component of the left-handed passing through the transmitting portion FA ₁ (white arrow) and counterclockwise polarized light component having passed through the transmitting portion FB ₁ (filled arrow) is temporally incoherent (C) Therefore, they do not interfere with each other.

FIG. 16 shows the ninth polarization control member PCM.
4 shows a structure according to an embodiment, wherein a circular transmission part FA at the center is shown.₁Toso
Zone transmission part FB in the immediate vicinity of_TwoAnd the surrounding area
Ring transmission part FB_ThreeAnd a triple structure. Where the yen
Shape transmission part FA₁And the outermost annular transmission part FB_ThreeSame polarization as
It is a polarizing plate that transmits the state, and the intermediate annular transmission portion FB _Two
Is a polarizing plate that passes a polarization state orthogonal to them,
The direction is as shown in FIG. Here the middle wheel
Band transmission part FB_TwoTransmitted light and circular transmission part FB₁With the transmitted light of
The principle of increasing the depth of focus due to the luminous flux created by
Street, circular transmission part FA₁And the outermost annular transmission part FB_Three
Are in the same polarization state, and the incident angle on the wafer W is
Wide range from sinθ = 0 (normal incidence) to NAw
Range. However, the circular transmission part FA₁
And annular transmission part FB_ThreeIs a kind of triple focus filter.
Therefore, a large depth of focus can be obtained. That
About the triple focus filter, January 23, 1961
Issued with Mechanical Testing Laboratory Report No. 40 “Optical System
Study on Imaging Performance and Its Improvement Method "
Details are given on pages 41 to 55 in the dissertation.

FIG. 17 shows the polarization control member PCM of FIG.
Shows a modification of, the circular transmitting portion FA ₁ and the outermost annular transmitting portion FB ₃ of a polarizing plate through the same polarization component, the direction of the polarization component orthogonal to their annular transmitting portion FB ₂ of intermediate It is a polarizing plate that passes through. However, the circular transmission part FA ₁ has the configuration shown in FIG.
(A), the are further phase plate for shifting the optical path length difference by half wavelength (phase film) FC ₂ provided for the outermost annular transmitting portion FB ₃ of the transmitted light. Thus, by inverting the circular transmitting portion FA ₁ and the outermost annular transmitting portion FB ₃ with the respective transmitted light phase (amplitude), to form a double focus filter in that portion, the effect of increasing the depth of focus Is obtained. Of course the incident angle range of the light beam also the wafer W from the middle of the annular transmitting portion FB ₂ is narrow, contributing to an increase in depth of focus. Each of the transmission parts FA ₁ and F ₁ shown in FIGS.
The maximum effect can be obtained if the diameters of B ₂ and FB ₃ are determined so that they are substantially equal in area. This means that the optical path length difference ΔZ shown in FIG. 3 is used for each transmission part FA ₁ , FB ₂ , F
Means that approximately equally divided by the light flux of each of B _3.

FIG. 18 shows a tenth embodiment of the polarization state controlling member PCM.
Is composed of a, it is provided with a circular light-shielding portion FD ₁ further center. In this case the incident angle range of the wafer W of the imaging light beam, and the radius of the light-shielding portion FD ₁ and K _1, FIG. 18
As shown in (C), it is limited to two light fluxes (each transmitted light of the transmission parts FA and FB) from sin θ _K1 to NAw. At this time, considering the light-shielding portion FD ₁ , the imaging light flux existing within the incident angle range NAw is divided into three, so that the angle range of one light flux (optical path difference ΔZ due to defocus) is also divided into three. As a result, the optical path difference that adversely affects the defocusing is reduced. As a result, the depth of focus can be further increased.

[0052] Figure 19 is reversed the relationship between the transmitting portion FA and the light shielding portion FD ₁ shown in FIG. 18, is provided with a ring-shaped light shielding portion FD _2. The width of the light shielding portion FD ₂ at this time is K ₂ -K ₁
As shown in FIG. 19C, the incident angle range θ _K2 −
A part of the imaging light flux is blocked during θ _K1 . In the case of FIG. 19, the same effect as in the case of FIG. 18 can be obtained. In the meantime, in the polarization state controlling member PCM shown in FIGS. 16 to 19, the central circular transmission portion or the annular transmission portion is formed as a polarizing plate, but as shown in FIGS. A wave plate or an optical rotation material may be used. The light-shielding portion FD _1, FD ₂ in FIG. 18 and 19, for example, may be a light shielding film on the polarizing plate and a wavelength plate on the deposition of metal film or the like, more provided apart from the polarized state control member PCM metal It may be a plate or the like.

Since the light shielding portions FD ₁ and FD ₂ or a light shielding plate equivalent thereto need only shield light at the exposure wavelength, an exposure wavelength (eg, an optical sharp cut filter using a dielectric thin film or the like) is used. A material that absorbs a short wavelength region such as ultraviolet light) may be used. This way,
For example, when a TTL alignment system that irradiates an alignment mark on the wafer W with a He-Ne laser as a light source and detects reflected light or the like via the projection optical system PL is used, a light shielding unit FD ₁ located on a pupil plane. , FD ₂ , or the light-shielding plate does not have an adverse effect (light-shielding) on the reflected light from the mark. Alternatively, a light-shielding plate made of the above-mentioned metal or the like or a light-shielding portion FD ₁ or FD ₂ through which a laser beam for illuminating a wafer mark or reflected light from the mark passes may be used as a transmission region only. Is not particularly impaired.

FIG. 20 shows the TTL according to the eleventh embodiment.
An example of an alignment system is shown.
GR is formed, and the position of the mark GR in the lattice pitch direction is
It is assumed that misalignment is detected. Here, FIG.
From the direction where the horizontal direction on the surface is the pitch direction.
Fig. 20 (B) is a view of the system of Fig. 20 (A).
Is viewed from a direction rotated by 90 °. Retic
Objective lens of the alignment optical system provided above
OBJ provides a coherent laser beam (He-N
e) ALB₁, ALB_TwoAre reflected by the mirror MR.
After crossing at the plane CF, the window RM around the reticle R
Through the projection optical system PL. First, in FIG.
As shown, two beams ALB₁, ALB_TwoIn the eyes
A bending compensator formed on the located polarization state controlling member PCM
Positive element PG₁, PG_TwoIncident on each of the
Two beams AL with an amount corresponding to the axial chromatic aberration of the system PL
B ₁, ALB_TwoChange the direction of travel. With this two
Beam ALB₁, ALB _TwoIs the lattice mark on the wafer W
GR at an angle symmetrically inclined with respect to the pitch direction.
Irradiate. At this time, the pitch Pg of the lattice mark GR, the pitch
ALB₁, ALB_TwoWavelength λa and beam ALB
₁, ALB_TwoIs the incident angle θa of sin θa = λa / Pg
Is satisfied, the beam ALB₁Grating by irradiation
+ 1st-order diffracted light generated from mark GR and beam ALB
_Two-Order diffracted light generated from mark GR by irradiation of light
Means two beams ALB as shown in FIG.₁, A
LB_TwoAnd the interference beam AD
Reverse as L. This interference beam ADL is polarized state controlled.
Flexibility correction element PG formed on control member PCM_ThreeProgress in
The direction can be changed, and the alignment
Return to the optical system. At this time, FIG.
As shown in FIG.
Beam ALB₁, ALB_TwoIs the direction orthogonal to the pitch direction
(Interference direction)
ADL also occurs at an angle. Also, as shown in FIG.
Yeah, two beams ALB₁, ALB_TwoCrosses at plane CF
However, actually, the surface CF is made to coincide with the position of the window RM.
Can be That is, two beams ALB₁, AL
B_TwoAlmost completely compensates for the axial chromatic aberration caused by
be able to. Further, as shown in FIG.
Mu ALB₁, ALB_TwoTelecentric with respect to the non-measurement direction
To the window RM shifted from the
Thus, the chromatic aberration of magnification can be compensated. In addition, objective
The optical axis AXa of the lens OBJ is perpendicular to the reticle R.
Is set.

In measuring the displacement of the mark GR,
There are two ways. One of them is two beams AL
B₁, ALB_TwoFormed on the mark GR by the intersection of
Of the mark GR in the pitch direction with respect to the interference fringes
This is to detect this. For that, alignment
The returned interference beam ADL is photoelectrically detected in the optical system.
A photoelectric sensor and measure its output signal level.
No. One method is to use two beams ALB₁, ALB
_TwoSlight frequency difference between (eg 20-100 KHz
Degree), and the interference fringes generated on the mark GR are
Heterodyne method that runs at a speed corresponding to the frequency difference
You. In this case, two beams ALB₁, ALB _TwoFrequency
Create a reference AC signal with a number difference and output from the photoelectric sensor.
Force signal (in the case of heterodyne, the interference beam ADL is
Signal because the intensity changes at the same frequency)
By calculating the phase difference between
Can be measured.

As described above, when the bending correction elements PG ₁ , PG ₂ , PG ₃ for chromatic aberration compensation are provided on the pupil plane of the projection optical system PL, the light-shielding portion FD shown in FIGS. ₁ , the position may interfere with the shape of the FD ₂ (or light shielding plate). However, this type of alignment beam ALB ₁ , ALB ₂ or interference beam ADL has a very small spot diameter,
Each dimension of the correction elements PG ₁ , PG ₂ and PG ₃ may be extremely small. Usually built as a phase grating correction element PG ₁ ~PG ₃ by etching or the like on the surface of a transparent glass material. Therefore, as described above, the light shielding portion F
When D ₁ and FD ₂ interfere with each other in position, only the light shielding portion at that position may be made a transparent portion.

In FIG. 20, the correction elements PG _{1 to} PG ₃
Is formed directly on the polarization state control member PCM, but a normal quartz plate on which the correction elements PG _{1 to} PG ₃ are formed is fixedly arranged on the pupil plane, and the polarization state control member PCM is May be removably disposed in the very vicinity of. Note that a method of providing a small-diameter correction lens (convex lens) at the center of the pupil plane of the projection optical system PL and compensating for the chromatic aberration of the alignment beam by using, for example, US Pat.
P. 5,100,237. in this case,
When a dichroic film having a small transmittance for the exposure wavelength and a very high transmittance for the wavelength of the alignment beam is deposited on the correction lens portion, the central light-shielding portion FD _{1 of} the polarization control member PCM shown in FIG. Substantially equivalent ones can be easily configured. However, the above USP.
5, 100, and 237 have transmission portions FA as shown in FIG.
There is no suggestion of providing FB at the same time.

In the drive unit 22 of the wafer stage WST shown in FIG. 4, the function of the conventional FLEX method may be provided in the control for finely moving the wafer W in the optical axis direction. By using the FLEX method together, the effect of increasing the depth of focus according to the present invention can be dramatically increased. The present invention can be applied to any type of projection exposure apparatus. For example, it may be a stepper type using a projection lens, a step-and-scan type using a catadioptric system, or a 1: 1 mirror projection type. In particular, in a scan type (step-and-scan) or mirror projection system, exposure is performed while scanning and moving a reticle or a wafer in a plane perpendicular to the optical axis of a projection optical system, and it has been considered difficult to apply the conventional FLEX method. However, the present invention has an advantage that it can be applied to such a scanning type exposure apparatus very easily.

A case in which the present invention is applied to an equal-size mirror projection type aligner will be described as a twelfth embodiment with reference to FIGS. In FIG. 21, illumination light from a mercury lamp (Xe-Hg) lamp 1 is projected onto a reticle (mask) R via an illumination optical system ILS into an arc slit illumination area. The reticle R is held on a reticle stage RST capable of one-dimensional scanning,
It moves at the same speed in synchronization with wafer stage WST.
The projection optical system has a reflective surface MR on each of the reticle side and the wafer side.
_1, the optical block trapezoidal with MR _4, is composed of a large concave mirror MR ₂ with a small convex mirror MR _3, the concave mirror with respect to the radius of curvature of the convex mirror MR ₃ M
The radius of curvature of R ₂ is set to about twice. This FIG.
In the case of such a system, the surface of the convex mirror MR _{3 is} the Fourier transform surface F with respect to the reticle pattern surface (or wafer surface).
Often coincides with TP.

At this time, the imaging light flux generated from the point Pr on the reticle R is reflected along the principal ray LLP by the reflecting surfaces MR ₁ ,
Upper concave mirror MR _2, the entire surface of the convex mirror MR _3, the lower side of the concave mirror MR _2, and proceeds in the order of the reflection surface MR _4,
It converges to a point Pr ′ on the wafer W. Even when this way the surface of the convex mirror MR ₃ has a pupil plane of the system, the polarization state control member PC used in the examples which have been described until now
M can be used as it is or with some modification.

[0061] Specifically, it is located very close to the polarization state control member PCM convex mirror MR ₃ as shown in FIG. 22, and when the concave mirror MR ₂ comes incident on the convex mirror MR _3, convex mirror MR ₃ from the optical path of the two and when going injected into the concave mirror MR ₂ (round trip), it is sufficient to control the polarization state of the imaging light beam. However, as shown in FIG. 6, FIG. 16, FIG. 18, and FIG. 19, each of the central circular (or annular) transmitting portion FA and the peripheral annular transmitting portion FB is simply constituted by only a polarizing plate. Can be used as it is, but a half of the transmission parts FA and FB can be used.
When using the configurations shown in FIGS. 7, 9 to 12 and 17 using a wave plate or a quarter wave plate, a half wavelength is considered in consideration of a double polarization action in the reciprocating optical path. The plate needs to be changed to a 波長 wavelength plate, and the ４ wavelength plate needs to be changed to a ８ wavelength plate.

In a projection exposure apparatus using an excimer laser as a light source, a secondary light source surface (a large number of point light sources) formed on the exit side of a fly-eye lens or the like is re-imaged on the pupil surface of the projection optical system. Therefore, optical elements (lens, reflective surface,
When an aperture stop, PCM, etc. are arranged, the optical element may be deteriorated due to the converged light source image due to long-term use. Therefore, it is preferable that the polarization state control members PCM and the like are not strictly arranged on the pupil plane, but rather are slightly shifted.

In each of the above embodiments, the polarization control member 6 shown in FIG. 4 is provided in the illumination optical system. May be located anywhere within the optical path of
For example, a linearly polarized laser is used as a light source, and a 波長 wavelength plate is used as a polarization control member 6 with a reticle R and a projection optical system PL.
To convert the entire imaging light flux generated from the reticle R into circularly polarized light.

Incidentally, since the lens and the reflecting surface of the projection optical system used in this type of exposure apparatus are made of a very uniform glass material, the polarization direction of the light beam entering the projection optical system and the polarization direction of the light beam exiting the projection optical system. Should be in good agreement with each other, but a slight deviation can occur. in this case,
Even if the polarization state control member PCM is ideally arranged, the polarization directions of the two light beams LFa and LFb will not be completely complementary. However, since the deviation from the complementary relationship is only a small amount, the effect of the present invention is not greatly impaired.

Next, the operation and effect obtained by each embodiment of the present invention will be described based on simulation results. FIG. 23A shows a square contact hole pattern PA having one side corresponding to 0.3 μm on the wafer used in the following simulation. In the following simulation, the cross section taken along the line AA ′ in FIG. Of the image intensity distribution on the wafer. FIG. 23 (B) shows FIG.
And the ratio r between the radius r ₁ of the center circular transmitting portion FA and the maximum radius r _{2 of the} pupil.
₁ / r _2, as mentioned at the principles described NA ₁ /
It is set so that NAw = 0.707. That is, the maximum incident angle of the imaging light flux passing through the transmission part FA is θ ₁
Then, it is determined that sin ² θ ₁ = 1/2 (NAw ² ) is satisfied. In the following simulations, NAw = 0.57 and the exposure wavelength was i-line (wavelength 0.
365 μm). The σ value, which is the coherence factor of the illumination light beam, was set to 0.6.
Now FIG. 23 (C), (D) , (E) shows the image intensity distribution on the wafer of the pattern PA, the intensity distribution I ₁ at the best focus position, respectively, the intensity distribution I ₂ at the defocus position of 1μm 2 is an intensity distribution I ₃ at a defocus position of 2 μm. Eth in FIGS. 23C, 23D and 23E indicates the strength required to completely remove (expose) the positive photoresist on the wafer, and Ec indicates the dissolution of the positive resist (film burrs). Indicates the strength at which to start. The magnification (exposure amount) in the vertical direction of each intensity distribution is such that the contact hole diameter (width of the slice portion crossing Eth) at the best focus is 0.
It was set to be 3 μm. FIG. 24 for comparison
(A), (B), the intensity distribution I ₇ at the best focus position by conventional exposure apparatus, respectively (minus the control member PCM) (C), the intensity distribution I ₈ at defocus position of 1 [mu] m, 2 [mu] m shows the intensity distribution I ₉ at defocus position of. The simulation conditions at this time are also NAw = 0.57, wavelength λ = 0.365 μm, σ =
0.6.

FIGS. 24A to 24C and FIG.
Comparing (D) to (F), it can be seen that the change in image intensity (decrease in contrast) at the time of defocus decreases and the depth of focus increases. On the other hand, FIG. 25 shows an image intensity distribution I ₁₀ when the FLEX method is combined with a normal projection exposure apparatus,
It shows changes in I ₁₁ and I ₁₂ . The exposure condition of the FLEX method was a total of three divided exposures, one for each of the best focus position and the position defocused by ± 1.25 μm. The simulation result of FIG. 25 and FIG.
Comparing the simulation results of FIGS. 3 (C) to 3 (E), it is understood that the effect of increasing the depth of focus in the present invention can be obtained to the same degree as in the FLEX method. FIG. 26 shows a simulation result when the polarization state controlling member PCM shown in FIG. 18 in the embodiment of the present invention is used. At this time, FIG.
As shown in the figure, the radius K ₁ of the circular light shielding portion FD ₁ at the center of the polarization state controlling member PCM is 0.31r ₂ (that is, sin θ).
_K1 = 0.31NAw) is the determined relationship, the radius K ₂ of the outer intermediate annular transmitting portion FA is assumed to be set in relation 0.74r ₂ (i.e. sinθ _K2 = 0.74NAw) . Of course, as the exposure condition, NAw =
0.57, σ = 0.6 and λ = 0.365 μm remain as they are. Even in the control member PCM as shown in FIG. 26 (B), the intensity distribution I ₄ at the best focus position and the intensity distribution I at the 1 μm defocus position as shown in FIGS. 26 (C), (D) and (E). ₅ , a sufficient effect of increasing the depth of focus can be obtained as in the intensity distribution I ₆ at the defocus position of 2 μm.

FIG. 27 shows a conventional Super for comparison.
9 shows a simulation result by the FLEX method. FIGS. 27A, 27B, and 27C show a filter having a numerical aperture NAw of 0.57 and a complex amplitude transmittance of -0.3 within a radius of 0.548 NAw from the pupil center point. The intensity distribution I ₁₃ at the best focus position, the intensity distribution I ₁₄ at the defocus position of 1 μm, and the intensity distribution I ₁₅ at the defocus position of 2 μm are obtained. In the Super FLEX method, as shown in FIG. 27, the central intensity at the best focus position is high and the profile is sharp, but the central intensity decreases sharply from a certain amount due to the defocus amount. However, the effect of increasing the depth of focus is almost the same as the effect of the present invention shown in FIGS. However, Super F
In the LEX method, the image shown in FIG.
A sub-peak (ringing) as shown in FIG. This is not a problem with the isolated contact hole pattern PA serving as a simulation model in FIG. 27, but it is a significant problem when applied to a plurality of close contact hole patterns described later.

FIGS. 28 (A), (B) and (C) show a case where a filter whose action is weaker than that of the pupil filter of the Super FLEX method used as a simulation model in FIG. 27 is used to prevent such ringing. The simulation result in the case is shown. In this case, the numerical aperture NAw of the projection optical system is 0.57, and the radius of the pupil center is 0.447NA.
A filter having a complex amplitude transmittance of −0.3 in a portion corresponding to w is used. Figure 28 (A) ~ (C) the intensity distribution at the best focus position, respectively I _16, the intensity distribution I ₁₇ at the defocus position of 1 [mu] m, show an intensity distribution I ₁₈ at the defocus position of 2 [mu] m, indeed FIG Although ringing is weaker than in the case of 27, the effect of increasing the depth of focus is also reduced.

FIGS. 29A to 29D show two contact hole patterns PA ₁ and PA ₂ adjacent to each other, for example, as shown in FIG.
The simulation results of the image intensity distribution obtained by various exposure methods when the lines are spaced apart by the center-to-center distance of 0.66 μm (on the wafer) as in FIG. 9 (E) are shown. FIG.
(A) shows S under the same simulation conditions as in FIG.
FIG. 29 (B) shows an image intensity distribution obtained by the conventional FLEX method, and FIG. 29 (C) shows an image intensity distribution obtained by the FINCS method (the present invention). 29 shows the image intensity distribution obtained by the FLEX method (1), and FIG. 29D shows the image intensity distribution obtained by the Super FLEX method (2) under the same conditions as in FIG. It is at the best focus position. As can be seen from the simulation results, the images obtained in FIGS. 29 (A), (C) and (D) are 2
Since the intensity between the two hole images is lower than the film bulging intensity Ec, the resist (positive type) between the two holes completely remains,
The resist images of both holes are separated and well formed. However, in the FLEX method shown in FIG. 29B, the intensity between the two hole images is not sufficiently low, and the resist between the two holes is filmed, so that a good pattern cannot be formed. That is, the images of the two contact holes may be connected due to a slight difference in the exposure amount. As described above, although the SFINCS method of the present invention and the conventional FLEX method can obtain the same depth of focus when projecting an isolated contact hole pattern, the resolution (fidelity) of the close hole pattern can be improved. In terms of the SFINC of the present invention
It can be seen that the S method is superior to the FLEX method.

In the simulations of FIGS. 29C and 29D, two hole patterns PA ₁ and PA ₂ are set under the condition that the peak of the ringing due to one hole pattern overlaps with the center intensity portion of the other hole pattern. , The effect of ringing does not appear between the two hole pattern images. This means that if the distance between the centers of the _two hole patterns PA ₁ and PA ₂ is different from the previous condition (0.66 μm on the wafer), the influence of ringing appears.

FIG. 30 is a simulation result of an intensity distribution at the best focus position of two contact hole images arranged at a center-to-center distance of 0.96 μm (converted on a wafer). The image intensity distribution I ₂₃ according to the SFINCS method (the present invention) under the conditions shown in FIG. 26 is 2 as shown in FIG.
The space between the two hole images is sufficiently dark, and a good resist pattern can be formed. However, under the conditions shown in FIG.
In uper FLEX method (1), as the intensity distribution I ₂₄ in FIG. 30 (B), ringing due each of two hole pattern will be synthesized (added), two intermediate bright sub peak (film hole images (Veri strength Ec or more) is generated, and the resist in this portion is film-verified. Therefore, a good resist image cannot be obtained. On the other hand, when two hole patterns having a center-to-center distance of 0.96 μm are projected by the Super FLEX method (2) under the conditions shown in FIG. 28, the image intensity distribution I ₂₅ becomes as shown in FIG. . As described above, the comparatively weak Supe
In the case of the r FLEX method (2), a good resist image can be obtained since there is little ringing and no film burrs. However, under this condition, as described with reference to FIG. 28, a sufficient depth of focus effect cannot be obtained as compared with the SFINCS method of the present invention.

FIG. 31 shows another projection exposure method in which the effective radius r ₂ of the pupil is 0.7 mm on the pupil plane of the projection optical system.
It shows an image intensity distribution I ₂₆ of an isolated hole pattern obtained when only a circular light-shielding plate having a radius of 07 times (NAw × 0.707) is arranged. In this case, ringing also occurs around the original image,
It is difficult to apply a close contact hole pattern to projection exposure.

FIG. 32 shows contact hole patterns PA ₁ , PA ₂ , PA ₃ , PA used in a memory cell portion in a DRAM as an example of a plurality of contact holes close to each other.
₄ shows an example of a two-dimensional array of ₄ . When the Super FLEX method is used for such a hole pattern group, ringing (sub-peak) occurs around each hole.
Ra, Rb, Rc, Rd are generated, and the region R in which they overlap
At o, the respective peak intensities of the four ringings overlap. In such a case, when only two hole patterns (two ringings overlap), Super FLE, which is relatively ineffective and has no film burrs, is generated.
Even in the case of the X method (2), the size of the
This is about twice as large as the state shown in FIG.
c or more, good pattern transfer cannot be performed. That is, an image (ghost image) of a hole that does not originally exist on the reticle is formed at the position of the region Ro on the wafer.

On the other hand, in the case of the SFINCS method according to the present invention, as shown in FIG. 30 (A), the light intensity distribution between the two hole patterns is less than 1/2 of the film vertex intensity Ec. In the region Ro shown, even if the added intensity is further doubled from the state shown in FIG. Although the embodiments of the present invention and the operation thereof have been described above, when the illumination light ILB to the reticle R has a specific polarization direction, it is determined whether or not the polarization direction is appropriate, or the polarization state control member is used. In order to determine the quality of the polarization state of the imaging light beam after passing through the PCM, means for photoelectrically detecting a part of the light beam that has passed through the projection optical system may be provided on the wafer stage WST. When a reticle having a line and space is used, the polarization state control member PCM may be moved out of the projection optical system PL, and a part of the illumination system may be replaced so as to be suitable for the SHRINC method. Note that the polarization state control member PCM may be used at the time of projection exposure of the contact hole pattern, and a modified illumination system such as the SHRINC method or an annular illumination light source may be used together. In this case, when exchanging the reticle to be exposed from the contact hole to the line and space, only the polarization state control member PCM needs to be withdrawn.

Further, the polarization state controlling member PCM shown in each embodiment of the present invention is constituted by a circular or annular transmission part, but this is not limited to a literal shape. For example, the circular transmission portion may be deformed into a polygon including a rectangle, and the annular transmission portion may be deformed into a shape surrounding the polygon in a ring shape. Further, the polarization state control member PCM
Has been configured with a maximum of two or more annular transmission parts surrounding the central circular transmission part, but the annular transmission part may be divided into more parts. In this case, the area of each of the circular transmission portion and each of the n-fold annular transmission portions is set to be substantially equal, that is, the area is set such that the effective aperture area of the pupil is divided into n + 1 equal parts.

[0076]

As described above, according to the present invention, the depth of focus at the time of projection exposure of an isolated pattern such as a contact hole is set to F.
It can be enlarged to the same extent as the LEX method or the Super FLEX method, and without moving or vibrating the photosensitive substrate in the optical axis direction unlike the FLEX method,
Another advantage is that it is not necessary to create a spatial filter having a complex function of complex amplitude transmittance unlike the Super FLEX method. In particular, in the present invention, the ringing itself, which is likely to occur due to spatial filtering on the pupil plane (Fourier transform plane) of the projection optical system, is kept sufficiently small, so that a plurality of contact hole patterns are arranged relatively close. Even if it is done, Super
As in the case of the FLEX method, there is obtained a great effect that there is no adverse effect (such as generation of a ghost image) caused by superimposition of the ringing subpeak portion.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a conventional projection exposure method.

FIG. 2 is a diagram showing a basic configuration for carrying out a projection exposure method of the present invention.

FIG. 3 is a diagram illustrating the principle of increasing the depth of focus by the exposure method of the present invention.

FIG. 4 is a diagram showing an overall configuration of a projection exposure apparatus suitable for implementing the present invention.

FIG. 5 is a partial sectional view showing a partial structure of a projection optical system.

FIG. 6 is a diagram showing a configuration of a polarization state control member PCM according to the first embodiment of the present invention.

FIG. 7 is a diagram showing a configuration of a polarization state controlling member PCM according to a second embodiment of the present invention.

FIG. 8 is a diagram showing a configuration of a polarization control unit for uniformly aligning polarization characteristics of illumination light.

FIG. 9 is a diagram showing a configuration of a polarization state controlling member PCM according to a third embodiment of the present invention.

FIG. 10 is a diagram showing a configuration of a polarization state controlling member PCM according to a fourth embodiment of the present invention.

FIG. 11 is a diagram showing a configuration of a polarization state control member PCM according to a fifth embodiment of the present invention.

FIG. 12 is a diagram showing a configuration of a polarization state control member PCM according to a sixth embodiment of the present invention.

FIG. 13 is a diagram showing a configuration of a polarization control unit according to a seventh embodiment for making polarization characteristics of illumination light different from each other and simultaneously making them incoherent with time.

FIG. 14 is a diagram showing a configuration of a polarization control member PCM according to a seventh embodiment of the present invention.

FIG. 15 is a diagram showing a configuration of a polarization state controlling member PCM according to an eighth embodiment of the present invention.

FIG. 16 is a diagram showing a configuration of a polarization state controlling member PCM according to a ninth embodiment of the present invention.

FIG. 17 is a view showing a modification of the configuration of FIG. 16;

FIG. 18 is a diagram showing a configuration of a polarization state controlling member PCM according to a tenth embodiment of the present invention.

FIG. 19 is a view showing a modification of the configuration of FIG. 18;

FIG. 20 shows a configuration according to an eleventh embodiment of the present invention,
1 shows a configuration of a projection optical system when an alignment system is used.

FIG. 21 shows a configuration of a mirror projection type aligner according to a twelfth embodiment of the present invention.

FIG. 22 shows a state in which the polarization state control member PCM according to each embodiment of the present invention is applied to the aligner of FIG.

FIG. 23: SF of the present invention for a single hole pattern
4 shows a graph simulating the effect of the INCS method as an image intensity distribution.

FIG. 24 is a graph simulating the effect of a conventional normal exposure method on a single hole pattern as an image intensity distribution.

FIG. 25 shows a conventional FLE for a single hole pattern.
4 shows a graph simulating the effect of the X method as an image intensity distribution.

FIG. 26: SF of the present invention for a single hole pattern
4 shows a graph simulating the effect of the INCS method as an image intensity distribution.

FIG. 27 shows a conventional Sup for a single hole pattern.
3 shows a graph simulating the effect of the er FLEX method (1) as an image intensity distribution.

FIG. 28 shows a conventional Sup for a single hole pattern.
3 is a graph illustrating the effect of the er FLEX method (2) as an image intensity distribution.

FIG. 29 is a graph simulating the effect of various exposure methods on two close hole patterns as an image intensity distribution.

FIG. 30 shows the distance between two close hole patterns in FIG.
9 is a graph simulating the effects of various exposure methods as an image intensity distribution when considering the case of No. 9.

FIG. 31 shows a case where only a circular light-shielding portion is provided at the center of the pupil.
9 is a graph showing that ringing occurs in the image intensity distribution of a single hole pattern.

FIG. 32 shows a relationship between contact hole patterns distributed two-dimensionally and ringing occurrence positions.

[Explanation of symbols]

R · · · reticle W · · · wafer PL · · · projection optical system AX · · · optical axis PA, PA _1, PA ₂ ··· hole pattern PCM · · · polarization-state control member FA · · · circular transparent Part FB: annular transmission part ILB: illumination light

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-226225 (JP, A) JP-A-1-220825 (JP, A) JP-A-2-142111 (JP, A) JP-A-63- 64037 (JP, A) JP-A-4-179958 (JP, A) JP-A-4-336416 (JP, A) JP-A-5-21312 (JP, A) JP-A-6-224106 (JP, A) JP-A-6-244082 (JP, A) JP-A-6-124870 (JP, A) JP-A-6-163362 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 21/027

Claims (20)

(57) [Claims] 1. A projection exposure apparatus which illuminates a mask on which a pattern is formed and guides light from the pattern onto a substrate, the projection exposure apparatus being provided between the mask and the substrate, and A projection exposure apparatus, comprising: conversion means for converting light into a plurality of lights with reduced interference. 2. The method according to claim 1, wherein the conversion unit has a first area and a second area through which light from the pattern passes, and converts light passing through the first area with light passing through the second area. The projection exposure apparatus according to claim 1, wherein interference between the projection exposure apparatuses is reduced. 3. A projection optical system for forming an image of light from the pattern on the substrate, wherein the conversion means includes an optical Fourier transform surface with respect to a pattern surface of the mask in the projection optical system or in the vicinity thereof. The projection exposure apparatus according to claim 1, wherein the projection exposure apparatus is arranged in a position. 4. The projection exposure apparatus according to claim 1, wherein said conversion means has a polarizing member for making the polarization characteristics of the plurality of lights different from each other. 5. The apparatus according to claim 2, wherein said conversion means has a polarizing member for making polarization characteristics of light passing through said first region and light passing through said second region different from each other. 4. The projection exposure apparatus according to 3. 6. The projection exposure apparatus according to claim 5, wherein said conversion means has a quarter-wave plate on the exit surface side of said polarizing member. 7. The projection exposure apparatus according to claim 6, wherein said polarizing member comprises a 波長 wavelength plate and a transparent optical element or a 波長 wavelength plate and a transparent optical element. 8. The apparatus according to claim 2, wherein the first area is an area centered on an optical axis of the projection optical system, and the second area is an area outside the first area. 8. The projection exposure apparatus according to any one of 3, 5, 6, and 7. 9. The apparatus according to claim 8, wherein the first area is a circular area centered on the optical axis of the projection optical system, and the second area is an area outside the circular area. 3. The projection exposure apparatus according to claim 1. 10. The projection exposure apparatus according to claim 9, wherein the area of the circular region is substantially half the effective opening area of the Fourier transform surface in the projection optical system. 11. The apparatus according to claim 11, wherein the first area is an annular area centered on an optical axis of the projection optical system, and the second area is inside or outside the annular area. Item 8. The projection exposure apparatus according to any one of Items 2, 3, 5, 6, and 7. 12. The first area is a circular area centered on the optical axis of the projection optical system, and the second area is an annular area surrounding the circular area at least twice. The projection exposure apparatus according to claim 2, wherein each of the annular zones has a different polarization characteristic. 13. A circular or annular light-shielding member centered on the optical axis of said projection optical system is provided on or near said Fourier transform plane.
The projection exposure apparatus according to any one of 7, 8, 9, 10, 11, and 12. 14. A projection exposure apparatus according to claim 13, further comprising a drive mechanism for enabling at least one of said conversion means or said light shielding member to be inserted and removed between said mask and said substrate. . 15. The projection according to claim 1, further comprising a moving mechanism for relatively moving the substrate and the projection optical system in an optical axis direction of the projection optical system. Exposure equipment. 16. Illuminating a mask on which a pattern is formed,
In the projection exposure method for guiding light from the pattern onto a substrate, between the mask and the substrate, the light from the pattern is converted into a plurality of lights in which mutual interference is reduced, A projection exposure method, wherein the light is guided to the substrate. 17. The projection exposure method according to claim 16, wherein at least two of the plurality of lights have different polarization characteristics from each other. 18. The projection according to claim 17, wherein when the plurality of lights are guided to the substrate, the substrate and the projection optical system are relatively moved in an optical axis direction of the projection optical system. Exposure method. 19. A method for manufacturing a semiconductor integrated circuit by using the device according to claim 1. Description: 20. A method for manufacturing a semiconductor integrated circuit by the method according to claim 16.