JPH11204432A - Optical device and projection aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical device and a projection aligner capable of increasing the depth of focus of a projected contact hole pattern. SOLUTION: The SFINCS method is applied to convert the two imaging luminous flux (LFa, LFb) into incoherent state by setting a polarizing filter, 1/2 wavelength plate, 1/4 wavelength plate, or a rotary polarization material eliminating coherence between the imaging luminous flux LFa passing through a central circular region of the pupil of a projection optical system and the imaging luminous flux LFb passing though an annular region surrounding the central circular region on the pupil plane.

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 L1, L2, L3, La, L traveling in various directions from point A
Of the rays a ′ and La ″, the ray L1 is generated at an angle that cannot enter the lens system GA of the projection optical system.
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. NAw = sin .theta.w on the wafer (image surface) side, and is expressed by NAw = sin .theta.w. Therefore, the angle .theta.r formed by the rays La 'and La "with the principal ray La on the reticle R side is the reticle (object plane). The numerical aperture on the side is called 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 with 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 (Super High Resolution)
on by IllumiNation Contro
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 uses FLEX (Focu).
s Latitude 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]

In order to solve the above-mentioned problems, according to the present invention, an illumination means (1-1) for irradiating a mask (reticle R) on which a fine pattern is formed with illumination light for exposure.
4) and a projection optical system (PL) for projecting light generated from the pattern of the mask and projecting an image of the pattern on the sensitive substrate (wafer W). A circular area (FA) which is arranged on the Fourier transform plane (FTP) in the imaging optical path between or on the plane near the Fourier transform plane and on the Fourier transform plane or on the plane near the optical axis of the projection optical system A polarization state control means (polarization state control member PCM) for making the polarization states of the imaging light (LFa) distributed in the inside and the imaging light (LFb) distributed in the outside area (FB) different from each other is provided. I did it.

[0017]

According to the present invention, a polarization state control member is provided on a surface (hereinafter abbreviated as a pupil surface) in a projection optical system which is optically Fourier-transformed with respect to a reticle pattern surface, or on a surface in the vicinity thereof. A part of the imaging light distributed in a circular or annular shape in the pupil plane and the imaging light distributed in the other part are in a polarization state that does not interfere with each other. 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. Conventional Super-
Even in the FLEX method, since the imaging light distributed on the pupil plane is only partially phase-shifted, it is still a 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 · sin2 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 (.DELTA.F.NAw2). 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 equation 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 imaging in 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 θ1,
The maximum value of the optical path difference ΔZ1 when the defocus amount is ΔF is Δ
Z1 = 1/2 (.DELTA.F.sin2 .theta.1). FIG.
The horizontal axis of the graph at the bottom of represents the sine of the incident angle, and sin
It is assumed that θ1 = NA1. On the other hand, in the amplitude synthesis in the light beam LFb passing through the peripheral portion as shown in FIG. 3B, since the light beam LFb has an incident angle range from the incident angle θ1 to the numerical aperture NAw (sin θw), the defocus amount is ΔF. The maximum optical path length difference ΔZ2 at the time is ΔZ2 = １ ／ (ΔF) (NAw2
−sin2 θ1).

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 caused only by the optical path length differences ΔZ1 and ΔZ2 in the light beam. For example, sinθ1 is set so that sin2θ1 = １ ／ (NAw2), 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 ΔZ1 due to the first light beam LFa and the maximum optical path difference ΔZ due to the second light beam LFb are set.
2 is as follows. ΔZ1 = １ ／ (ΔF · sin2 θ1) = １ ／ (ΔF
・ NAw2) ΔZ2 = 1/2 (ΔF) (NAw2-sin2θ1) = 1/4
(ΔF · NAw2) Thus, the 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 technique of exchanging the image-forming light beam with a plurality of light beams that do not interfere with each other on the pupil plane ep of the projection optical system PL will be hereinafter referred to as SFINCS (Spatial Filter for).
The method will be referred to as “INCoherent Stream” 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, when performing the exposure operation of the lithography process using a plurality of steppers, it is hesitant to assign a specific one stepper to the exposure dedicated to the contact hole pattern in consideration of the most efficient operation of each stepper. 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. FIG. 5 shows a partial cross section of the projection optical system PL made entirely of a refractive glass material, and shows the lowermost lens GA1 of the front lens system GA and the uppermost lens GB1 of the rear lens system GB. A Fourier transform plane FTP exists in the space between them. 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 r1 of the circular transmission portion FA that gives the first polarization state
Is relative to the effective maximum radius r2 of the pupil ep,

[0035]

(Equation 2)

In practice, it is better to be larger by about several percent. As is apparent from this equation, the area πr12 of the circular transmitting portion FA is about half of the area πr22 of 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 controlling member PCM shown in FIG. 6 is constituted by a polarizing plate which transmits only linearly polarized light in a specific direction in a circular transmission portion FA having a radius r1 from the center point CC, and has a ring-shaped peripheral transmission coaxial with the center point CC. The portion FB is formed of a polarizing plate that transmits only linearly polarized light in a direction orthogonal to the circular transmission 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
, Each of which synthesizes amplitude only with itself and creates separate images (intensity distribution) Pr1 'and Pr2', the principle of increasing the depth of focus of the composite image (composite intensity distribution) is the term of action As mentioned.

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. FIG. 9B shows the planar structure of the polarization control member PCM. The circular transmitting portion FA1 having a radius r1 is formed of a half-wave plate, and the peripheral annular transmission portion FA2 is formed of the transmitting portion FA1 (1/2 wavelength). This is a normal transparent plate (for example, quartz) having a thickness (optical thickness) substantially equal to that of the plate. As shown in FIG. 9 (C), the polarization state of the light immediately after passing through the polarization state control member PCM in FIG. At the transmission part FA2, the polarization state does not change at all. 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 the axial direction that converts the direction of the incident linearly polarized light into a direction orthogonal to it, 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
This is a fourth embodiment in which both a circular transmission portion FA2 having a radius r1 and a peripheral annular transmission portion FB2 having a radius r1 are formed of quarter-wave plates (having the same thickness). Also in this case, the incident light beams are all linearly polarized as shown in FIG.
2 By optimizing the axial direction of the quarter-wave plate of FB2 with respect to the polarization state of the incident light beam, the light beam passing through the circular transmission portion FA2 becomes clockwise circularly polarized light as shown in FIG. Furthermore, the light beam that has passed through the annular transmission portion FB2 can be converted into counterclockwise circularly polarized light, and light beams (LFa, LFb) having different polarization states (not interfering with each other) can be obtained. Also in the case of the fourth embodiment, similarly to the third embodiment, the polarization direction of the illumination light ILB is adjusted by the polarization control member 6 in accordance with the axial direction of the quarter-wave plate as the polarization state control member PCM. You should be able to do so. The half-wave plate as the circular transmission portion FA1 shown in FIG. 9B may be replaced with an optical rotation material such as quartz, and even in that case, the direction of linearly polarized light can be converted in the same manner. .

FIG. 11 is a fifth embodiment showing a configuration of a polarization state control member PCM suitable for circularly polarized illumination light ILB. This fifth embodiment basically uses the same polarization state controlling member PCM as the third embodiment (FIG. 9). Therefore, as shown in FIG.
The circular polarization state of the transmitted light can be reversed as shown in FIG. 11 (C) simply by configuring 1 with a half-wave plate. The peripheral annular transmission portion FB1 is a transmission object (a quartz plate or the like) having a thickness similar to that of the half-wave plate of the transmission portion FA1. In the case of FIG. 11B, as in the case of FIG. 9B, the annular transmission portion FB1 may 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 FA2 and the orbicular transmitting portion FB2 are each formed of a quarter-wave plate, and the axial directions of the quarter-wave plates are adjusted so as to be orthogonal to each other and combined.
In the case of FIG. 12, the light transmitted through each of the transmission portions FA2 and FB2 becomes 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 component (polarized light in the direction perpendicular to the paper surface) split by the beam splitter 6C is synthesized 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 × d1 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 d1, the combined P-polarized light component and S-polarized light component will be incoherent (non-coherent) in terms of time as well as having complementary polarization directions. 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 FA1 (（wavelength plate). The four light beams have different polarization directions, and do not interfere with each other because the transmission portions FA1 and FB1 are temporally incoherent even if the polarization directions are the same. That is, the S-polarized light component that has passed through the transmitting portion FA1 is converted into a P-polarized light component, and has the same polarization direction as the P-polarized light component that has passed through the transmitting portion FB1, but the two lights are temporally incoherent and thus interfere with each other. do not do. 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 = λ2 / 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. In FIG. 15C, for example, a left-handed polarized light component (white arrow) passing through the transmitting portion FA1 and a left-handed polarized light component (black arrow) passing through the transmitting portion FB1 are temporally incoherent. Do not interfere with each other.

FIG. 16 shows the structure of a ninth embodiment of the polarization state controlling member PCM. The central circular transmitting portion FA1 and the immediate surrounding annular transmitting portion FB2, and the peripheral annular transmitting portion FB3. And a triple structure. Here, the circular transmission portion FA1 and the outermost annular transmission portion FB3 are polarizing plates that transmit the same polarization state, and the intermediate annular transmission portion FB2.
Are polarizing plates that pass a polarization state orthogonal to them, and the polarization direction is as shown in FIG. Here, the principle of increasing the depth of focus due to the light beam generated by the transmitted light of the intermediate annular transmission portion FB2 and the transmitted light of the circular transmission portion FB1 is as described above. Section FB3
Are in the same polarization state, and the angle of incidence on the wafer W is also a wide range from sin θ = 0 (normal incidence) to NAw. However, the circular transmission part FA1
And the annular transmission portion FB3 constitute a kind of triple focus filter, so that a large depth of focus can be obtained. The triple focus filter was published on January 23, 1961. This is described in detail in pages 41 to 55 of a paper entitled "Study on Image Forming Performance in Optical System and Improvement Method Thereof" in Report No. 40 of Mechanical Testing Laboratory.

FIG. 17 shows the polarization control member PCM of FIG.
The circular transmission portion FA1 and the outermost ring-shaped transmission portion FB3 are polarizing plates that pass the same polarization component, and the intermediate ring-shaped transmission portion FB2 is a polarizing plate that passes a polarization component in a direction orthogonal to them. It is. However, the circular transmitting portion FA1 has the configuration shown in FIG.
As shown in (A), a phase plate (phase film) FC2 for shifting the optical path length difference by 波長 wavelength with respect to the transmitted light of the outermost annular zone transmitting portion FB3 is further provided. Thus, by inverting the phase (amplitude) of each transmitted light between the circular transmitting portion FA1 and the outermost annular zone transmitting portion FB3, a bifocal filter is formed at that portion and an effect of increasing the depth of focus is obtained. Can be Of course, the light flux from the intermediate annular transmission portion FB2 also contributes to an increase in the depth of focus because the range of the incident angle on the wafer W is narrow. Each of the transmission parts FA1 and FB2 shown in FIGS.
, FB3 are most effective if their diameters are determined so that they are substantially equal in area. This is illustrated in FIG.
The optical path length difference ΔZ shown in FIG.
3 means that they are almost equally divided by each light beam.

FIG. 18 shows a tenth embodiment of the polarization state controlling member PCM.
And a circular light shielding portion FD1 is provided at the center. At this time, the range of the angle of incidence of the image-forming light beam on the wafer W is as follows, assuming that the radius of the light shielding portion FD1 is K1.
As shown in (C), it is limited to two light fluxes (each transmitted light of the transmission parts FA and FB) from sin θK1 to NAw. At this time, considering the light-shielding portion FD1, 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 length difference ΔZ due to defocusing) is also divided into three. In addition, the optical path difference which has an adverse effect upon defocusing is reduced. As a result, the depth of focus can be further increased.

FIG. 19 shows an arrangement in which the relationship between the transmission part FA and the light-shielding part FD1 shown in FIG. 18 is reversed, and an annular light-shielding part FD2 is provided. At this time, the width of the light shielding portion FD2 is K2-K1.
As shown in FIG. 19C, the incident angle range θK2−
Part of the image forming light beam is shielded during θK1. 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 transmitting portion or the annular zone transmitting portion is a polarizing plate, but as shown in FIGS. A wave plate or an optical rotation material may be used. The light shielding portions FD1 and FD2 in FIGS. 18 and 19 may be, for example, a light shielding film obtained by depositing a metal film or the like on a polarizing plate or a wavelength plate, or a metal plate or the like provided separately from the polarization state controlling member PCM. May be.

Further, the light-shielding portions FD1, FD2 or a light-shielding plate equivalent thereto need only shield light at the exposure wavelength. Therefore, the exposure wavelength (UV light) can be reduced by using an optical sharp cut filter made of a dielectric thin film or the like. ) May absorb short wavelength regions. 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 a projection optical system PL is used, a light-shielding portion FD1 located on a pupil plane, There is no problem that the FD2 or the light-shielding plate adversely affects the light reflected from the mark (light-shielding). Alternatively, a laser beam for illuminating a wafer mark or a light-shielding plate made of the above-mentioned metal or the like through which reflected light from the mark passes or a light-shielding portion FD1 or FD2 may be used as a transmission region only if the area is small. It doesn't hurt.

FIG. 20 shows the TTL according to the eleventh embodiment.
An example of an alignment system is shown, in which a grid mark GR is formed on a wafer W, and a positional shift of the mark GR in a grid pitch direction is detected. Here, FIG. 20A is a view of the alignment system viewed from a direction in which the left-right direction on the paper is the pitch direction, and FIG. 20B is a view of FIG.
Is viewed from a direction rotated by 90 °. A coherent laser beam (He-N) is emitted from an objective lens OBJ of an alignment optical system provided above the reticle R.
e) The two light beams ALB1 and ALB2 are reflected by the mirror MR and intersect at the surface CF, and then enter the projection optical system PL via the window RM around the reticle R. First, as shown in FIG. 20A, the two beams ALB1 and ALB2 are incident on bending correction elements PG1 and PG2 formed on the polarization state controlling member PCM located at the pupil, where the projection optics are projected. Two beams AL with an amount corresponding to the axial chromatic aberration of the system PL
Change the direction of travel of B1 and ALB2. As a result, the two beams ALB1 and ALB2 irradiate the grid mark GR on the wafer W at an angle symmetrically inclined with respect to the pitch direction. At this time, the pitch Pg of the grating mark GR, the wavelength λa of the beams ALB1 and ALB2, and the beam ALB
1, the incident angle θa of ALB2 is sin θa = λa / Pg
Is satisfied, the + 1st-order diffracted light generated from the grating mark GR by the irradiation of the beam ALB1 and the beam ALB
2 means the -1st-order diffracted light generated from the mark GR as shown in FIG. 20A.
The interference beam AD is formed by making the optical path just in the middle of LB2 coaxial.
Reverse as L. The traveling direction of the interference beam ADL is changed by the flexibility correcting element PG3 formed in the polarization state controlling member PCM, and returns to the alignment optical system through the window RM of the reticle R. At this time, FIG.
As shown in FIG. 2, the two beams ALB1 and ALB2 reaching the mark GR on the wafer W are inclined with respect to a direction (non-measurement direction) orthogonal to the pitch direction, so that the interference beam ADL is also generated with an inclination. Also, as shown in FIG. 20A, the two beams ALB1 and ALB2 intersect at the surface CF, but the surface CF can actually be made to coincide with the position of the window RM. That is, the two beams ALB1, AL
The axial chromatic aberration generated for B2 can be almost completely compensated. Further, as shown in FIG. 20B, the two beams ALB1, ALB2 are shifted from the telecentric condition in the non-measurement direction and are incident on the window RM, whereby the chromatic aberration of magnification can be compensated. The optical axis AXa of the objective lens OBJ is set perpendicular to the reticle R.

In measuring the displacement of the mark GR,
There are two ways. One of them is two beams ALB1
, ALB2, the position of the mark GR in the pitch direction is detected with reference to the interference fringe formed on the mark GR. For this purpose, a photoelectric sensor for photoelectrically detecting the returned interference beam ADL may be provided in the alignment optical system, and the output signal level may be measured. One method is to use two beams ALB1, ALB
2 a small frequency difference between (eg 20-100 KHz
This is a heterodyne method in which interference fringes generated on the mark GR run at a speed corresponding to the frequency difference. In this case, a reference AC signal having a frequency difference between the two beams ALB1 and ALB2 is generated, and an output signal from the photoelectric sensor (in the case of heterodyne, the intensity of the interference beam ADL changes at the beat frequency, so that the signal becomes an AC signal). By determining the phase difference between the mark GR and the mark GR, the position deviation of the mark GR can be measured.

As described above, when the bending correction elements PG1, PG2, PG3 for compensating for chromatic aberration are provided on the pupil plane of the projection optical system PL, the light-shielding portions FD1, FD2 (FIG. Or, it may interfere with the shape of the light-shielding plate). However, since the beam ALB1, ALB2 or the interference beam ADL of this type of alignment has an extremely small spot diameter,
Each dimension of the correction elements PG1, PG2, PG3 may be extremely small. Normally, the correction elements PG1 to PG3 are formed as phase gratings on the surface of a transparent glass material by etching or the like. Therefore, as described above, the light shielding portion FD1
, FD2 interfere with each other, only the light-shielding portion at that position needs to be made transparent.

In FIG. 20, the correction elements PG1 to PG3
Is formed directly on the polarization state control member PCM, but a normal quartz plate on which the correction elements PG1 to PG3 are formed is fixedly arranged on the pupil plane, and the polarization state control member PCM is You may make it arrange | position so that insertion and removal are possible near. 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,
If 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, it is substantially the same as the central light shielding portion FD1 of the polarization control member PCM shown in FIG. 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, a trapezoidal optical block having an MR4, a large concave mirror MR2 and a small convex mirror MR3, and a concave mirror M with respect to the radius of curvature of the convex mirror MR3.
The radius of curvature of R2 is set to about twice. This FIG.
In the case of such a system, the surface of the convex mirror MR3 is the Fourier transform surface F with respect to the reticle pattern surface (or wafer surface).
Often coincides with TP.

At this time, the image forming light beam generated from the point Pr on the reticle R is reflected along the principal ray LLP by the reflecting surfaces MR 1, MR 1,
Proceed in the order of the upper side of the concave mirror MR2, the entire surface of the convex mirror MR3, the lower side of the concave mirror MR2, and the reflection surface MR4.
It converges to a point Pr ′ on the wafer W. As described above, even when the surface of the convex mirror MR3 is the pupil plane of the system, the polarization state control member PC used in each of the embodiments described above.
M can be used as it is or with some modification.

More specifically, as shown in FIG. 22, the polarization state controlling member PCM is disposed immediately adjacent to the convex mirror MR3, and when the polarization state controlling member PCM enters the convex mirror MR3 from the concave mirror MR2, and when the convex mirror MR3 enters the concave mirror MR2. It is sufficient to control the polarization state of the image forming light beam in two (reciprocating) light paths when the light is emitted to the light source. 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 of FIGS. 7, 9 to 12, and 17 using a wave plate or a quarter wave plate, the half wavelength is considered in consideration of the fact that the light is reciprocated twice 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 r1 between the radius r1 of the central circular transmitting portion FA and the maximum radius r2 of the pupil.
/ R2 is NA1 //, as described in the principle explanation.
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 θ1
Then, it is determined that sin2 θ1 = １ ／ (NAw2) 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.
23 (C), (D) and (E) show the image intensity distribution of the pattern PA on the wafer, and the intensity distribution I1 at the best focus position, the intensity distribution I2 at the 1 μm defocus position, and 2 μm, respectively. Is the intensity distribution I3 at the defocus position. 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), and (C) show the intensity distribution I7 at the best focus position, the intensity distribution I8 at the 1 μm defocus position, and the 2 μm The intensity distribution I9 at the focus position is shown. 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 I10 when the FLEX method is combined with a normal projection exposure apparatus,
This shows changes in I11 and I12. 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 K1 of the circular light shielding portion FD1 at the center of the polarization state controlling member PCM is 0.31r2 (that is, sin θ).
K1 = 0.31 NAw), and the radius K2 of the outer intermediate annular transmission portion FA is set to 0.74 r2 (that is, sin θK2 = 0.74 NAw). Of course, as the exposure condition, NAw =
0.57, σ = 0.6 and λ = 0.365 μm remain as they are. In the control member PCM as shown in FIG. 26B, as shown in FIGS. 26C, 26D and 26E, the intensity distribution I4 at the best focus position, the intensity distribution I5 at the 1 μm defocus position, As in the intensity distribution I6 at the defocus position of 2 .mu.m, a sufficient depth of focus effect can be obtained.

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 I13 at the best focus position and the intensity distribution I1 at the 1 μm defocus position obtained when
4 shows an intensity distribution I15 at a defocus position of 2 μm. 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. 28A to 28C show the intensity distribution I16 at the best focus position and the intensity distribution I17 at the 1 μm defocus position, respectively, and the intensity distribution I18 at the 2 μm defocus position. Ringing is weaker than in the case of, but at the same time, the effect of increasing the depth of focus is reduced.

FIGS. 29A to 29D show two adjacent contact hole patterns PA1 and PA2, 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, the center of the two hole patterns PA1 and PA2 is set under such a condition that the peak of the ringing due to one hole pattern overlaps the center intensity portion of the other hole pattern. Since the distance is determined, 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 PA1 and PA2 is different from the above 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 I23 by 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 the upper FLEX method (1), as shown in the intensity distribution I24 of FIG. 30B, ringing due to each of the two hole patterns is combined (added), and a bright sub-peak (film vertex) is provided between the two hole images. (Strength Ec or more) occurs, and the resist in this portion is subjected to film erosion. 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 I25 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 r2 of the pupil is set at 0.7 to the pupil plane of the projection optical system.
It shows an image intensity distribution I26 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 PA1, PA2, PA3, 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 FIG. 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 diagram showing a modified example 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, PA1, PA2: Hole pattern PCM: Polarization state control member FA: Circular transmission part FB ... Ring-shaped transmission part ILB ... Illumination light

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[Procedure amendment]

[Submission date] November 18, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Name of invention

[Correction method] Change

[Correction contents]

Patent application title: Optical apparatus and projection exposure apparatus

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction contents]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical device for preventing foreign matter such as dust from entering an optical path or a lens barrel and a projection exposure apparatus having the same. It is another object of the present invention to provide a projection exposure apparatus that can accurately measure an alignment mark via a projection optical system.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction contents]

[0016]

According to the first aspect of the present invention, there is provided an optical apparatus used in a projection exposure apparatus for transferring a mask pattern illuminated by illumination light onto a substrate. In the optical path of the illumination light, a space within the optical path that is shielded from the outside air is formed, and arranged in the space within the optical path, and a changing unit that changes the optical characteristics of the exposure light, and changes the optical characteristics of the exposure light. In order to achieve this, a control mechanism for controlling the change means and a storage member for storing the control mechanism and forming a storage space shielded from the outside air are provided. According to a twelfth aspect of the present invention, in a projection exposure apparatus for transferring light from a pattern on a mask illuminated with exposure light to a substrate via a projection optical system, the light is generated from an alignment mark formed on the substrate. Detecting means for detecting measurement light having a wavelength different from the exposure light via the projection optical system, and a detection means disposed near the pupil plane of the projection optical system and at a distance from the optical axis of the projection optical system. A deflecting optical member that deflects the measurement light toward a measurement area on a predetermined surface, and a filter that is disposed between the mask and the substrate and has a plurality of regions that make optical characteristics of light from the pattern different from each other. And a configuration including: Claim 1
In the invention described in Item 6, in a projection exposure apparatus that irradiates a mask with exposure light and exposes a substrate with the exposure light via a projection optical system, the exposure light has a different wavelength from the exposure light and a pupil of the projection optical system. A deflecting optical member that deflects the pair of measurement lights so that the pair of measurement lights passing through different positions on the surface is irradiated on the alignment mark, and a detection unit that detects light generated from the alignment mark. And a filter disposed between the mask and the substrate and having a plurality of regions that make optical characteristics of light from the pattern different from each other.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction contents]

[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.

[Procedure amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction contents]

According to the first aspect of the invention, it is possible to prevent dust from entering from outside air. Claims 13 and 16
According to the invention described in (1), even if the alignment mark is measured using measurement light having a wavelength different from the exposure light, the measurement light is hardly affected by the aberration of the projection optical system. Measurement of the alignment mark.

Claims (14)

[Claims] An illumination means for irradiating a mask on which a fine pattern is formed with illumination light for exposure, and an image of the pattern formed on a sensitive substrate by projecting light generated from the pattern of the mask. A projection optical system comprising: a projection optical system, comprising: a Fourier transform surface in an imaging optical path between the mask and the sensitive substrate, or a surface near the Fourier transform surface; And a polarization state control means for making the polarization states of the imaging light distributed in a circular region centered on the optical axis of the projection optical system and the imaging light distributed in a region outside the circular region different from each other. A projection exposure apparatus characterized by the above-mentioned. 2. An illuminating means for irradiating a mask on which a fine pattern is formed with illumination light for exposure, and projecting an image of the pattern on a sensitive substrate by irradiating light generated from the pattern of the mask. A projection optical system comprising: a projection optical system, comprising: a Fourier transform surface in an imaging optical path between the mask and the sensitive substrate, or a surface near the Fourier transform surface; Polarization that causes the polarization states of the imaging light distributed in the annular region centered on the optical axis of the projection optical system and the imaging light distributed inside or outside the annular region to be different from each other. A projection exposure apparatus comprising state control means. A second polarization control means provided in the illumination means or in an image forming optical path from the mask to the polarization state control means for adjusting the polarization of the image forming light to a specific state. 3. The projection exposure apparatus according to claim 1, wherein: 4. An illuminating means for irradiating a mask on which a fine pattern is formed with illumination light for exposure, and irradiating light generated from the pattern of the mask to form an image of the pattern on a sensitive substrate. A projection optical system comprising: a projection optical system, comprising: a Fourier transform surface in an imaging optical path between the mask and the sensitive substrate, or a surface in the vicinity thereof, on the Fourier transform surface, or a surface in the vicinity thereof First polarization state control means for making the polarization states of light distributed in a circular region centered on the optical axis of the projection optical system above and light distributed in a region outside the circular region different from each other; Means for generating a first illumination light having a uniform polarization characteristic and a second illumination light having a polarization characteristic different from the first illumination light and being temporally incoherent. And control means. Projection exposure equipment. 5. An illuminating means for irradiating a mask on which a fine pattern is formed with illumination light for exposure, and irradiating light generated from the pattern of the mask to form an image of the pattern on a sensitive substrate. A projection optical system comprising: a projection optical system, comprising: a Fourier transform surface in an imaging optical path between the mask and the sensitive substrate, or a surface in the vicinity thereof, on the Fourier transform surface, or a surface in the vicinity thereof First, the polarization states of illumination light distributed in an annular area centered on the optical axis of the projection optical system and illumination light distributed inside or outside the annular area are different from each other. Polarization state control means; first illumination light provided in the illumination means and having uniform polarization characteristics, and second illumination temporally incoherent with polarization characteristics different from the first illumination light. Second polarization control means for generating light And a projection exposure apparatus. 6. The polarization state control means comprises a pair of polarizing plates for making the polarization directions of transmitted light orthogonal to each other in the circular area or in the annular area and in the other area. The projection exposure apparatus according to any one of claims 1 to 5, wherein 7. The polarization state control means includes:
Alternatively, a pair of polarizers is used to set the circularly polarized light transmitted through the ring-shaped region and the other region to opposite states.
The projection exposure apparatus according to any one of claims 1 to 5, wherein the projection exposure apparatus comprises a composite member with a four-wavelength plate. 8. A projection exposure apparatus according to claim 1, wherein said polarization state control means comprises a quarter-wave plate or a half-wave plate. . 9. The projection exposure apparatus according to claim 1, wherein said polarization state control means is made of an optically rotatory substance. 10. A circular shape centered on the optical axis of the projection optical system, at or near a Fourier transform plane in the image forming optical path,
10. The projection exposure apparatus according to claim 1, further comprising a ring-shaped light shielding member. 11. The apparatus according to claim 1, further comprising a driving member for replacing at least one of said polarization state control means, said second polarization control means, and said light shielding member.
Item 11. The projection exposure apparatus according to any one of Items 10 to 10. 12. A moving mechanism for moving or oscillating the sensitive substrate in the optical axis direction of the projection optical system during exposure of the sensitive substrate or during a plurality of exposures. Item 12. The projection exposure apparatus according to any one of items 1 to 11. 13. A mask in which a plurality of isolated fine hole patterns are formed is uniformly irradiated with exposure illumination light having a predetermined incident angle range, and light from said mask is projected onto a projection optical system. By projecting each projected image of the plurality of hole patterns on the photosensitive substrate by projecting as an imaged light beam onto the photosensitive substrate via the, the Fourier transform surface in the projection optical system, or the When the imaging light flux distributed on the near surface is divided into a circular area centered on the optical axis of the projection optical system and an annular area surrounding the outside, each of the circular area and the annular area is divided into Provided in the projection optical system a polarization state conversion member that changes the polarization state between the imaging light fluxes that pass through and reach the photosensitive substrate, and the effective aperture area of the Fourier transform surface in the projection optical system. An exposure method for exposing a projected image of the hole pattern in a state where the area of the circular region is reduced to approximately half. 14. A mask in which a plurality of isolated fine hole patterns are formed is uniformly irradiated with exposure illumination light having a predetermined incident angle range, and light from said mask is projected onto a projection optical system. By projecting each projected image of the plurality of hole patterns on the photosensitive substrate by projecting as an imaged light beam onto the photosensitive substrate via the, the Fourier transform surface in the projection optical system, or the When the imaging light flux distributed on the nearby surface is divided into a circular region centered on the optical axis of the projection optical system and n orb-shaped regions surrounding the outside at least doubly, the circular region A polarization state conversion member that transmits each of at least two of the n ring-shaped areas and makes the polarization state of the imaging light flux reaching the photosensitive substrate different from each other is provided in the projection optical system, In a state in which the effective aperture area of the Fourier transform surface in the projection optical system is approximately n + 1 equally divided by the respective areas of the circular area and the n ring-shaped areas,
An exposure method, comprising exposing a projected image of the hole pattern.