JP3293882B2 - Projection exposure equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a projection exposure apparatus for forming a fine resist pattern required for manufacturing a semiconductor integrated circuit.

[0002]

2. Description of the Related Art In recent years, the progress of optical lithography has been remarkable, and there is a possibility that a 0.5 μm rule can be realized in a g-line (436 nm) or i-line (365 nm) projection exposure apparatus. This is because higher performance of the projection exposure apparatus, especially higher NA of the lens has been advanced. However, the next generation of.
It is doubtful that the 3 μm rule can be achieved with the conventional extension. Although the resolution is improved by increasing the NA of the lens and shortening the wavelength of the exposure light, the practical resolution is not significantly improved because the depth of focus is reduced. Therefore, development of a technology for improving the depth of focus is desired.

FIG. 23 shows a schematic configuration of a conventional projection exposure apparatus generally used. In this figure, 1 is a lamp composed of a mercury lamp, 2 is an elliptical reflecting mirror, 3 is a second focal point of the elliptical reflecting mirror 2, 4 is an input lens, 5 is an optical integrator (fly-eye lens), 6 is an output lens, 7 is a collimation lens, 8 is a reticle (mask), 9 is an aperture stop as a uniform stop, 10 is a filter for passing only light of a wavelength whose optical system is aberration-corrected, and 11 and 12 are optical path bending devices. Cold mirror for lowering the height of the lens, 13 is a lamp house, 14 is a projection optical system for projecting an image of a pattern on the reticle 8 onto a wafer by a lens, a mirror or a combination thereof, 15 is a wafer, and 16 is a numerical aperture. It is an aperture to do.

The basic configuration of a conventional projection exposure apparatus is shown in FIG.
Although there are many other than those shown in FIG.
1, a light source 1, a first condensing optical system 18, a uniforming optical system 19, a second condensing optical system 20, a reticle 8, a projection optical system 14, and a wafer 15 are arranged in this order. The first condensing optical system 18 is a part corresponding to the elliptical reflecting mirror 2 and the input lens 4 in the example of FIG.
A plane mirror, a lens, and the like are appropriately arranged, and have a role of allowing the light beam emitted from the light source to enter the uniforming optical system 19 as efficiently as possible. The homogenizing optical system 19 is a portion corresponding to the optical integrator 5 in FIG. 23, and an optical fiber, a polyhedral prism, or the like may be used as the other components.

The second condensing optical system 20 is a portion corresponding to the output lens 6 and the collimating lens 7 in FIG. 23, and superimposes the light emitted from the uniformizing optical system 19, and further secures the image plane telecentricity. In addition, a filter corresponding to the filter 10 of FIG. 23 is inserted at a position where the light beam is close to the optical axis parallel, and reflection mirrors corresponding to the cold mirrors 11 and 12 are also inserted, although the location is not unique.

When the light coming from the reticle 8 is viewed from the apparatus having the above-described configuration, the nature of the light becomes the nature of the light coming out of the homogenizing optical system 19 through the second condensing optical system 20. The exit side of the homogenizing optical system 19 appears as an apparent light source. For this reason, in the case of the above configuration, the exit side 24 of the homogenizing optical system 19 is generally called a secondary light source. When the reticle 8 is projected on the wafer 15, the formation characteristics of the projection exposure pattern, that is, the resolution and the depth of focus,
It is determined by the numerical aperture of the projection optical system 14 and the properties of the light irradiating the reticle 8, that is, the properties of the secondary light source 24.

FIG. 24B is an explanatory diagram relating to a reticle illumination light beam and an image forming light beam in the projection exposure apparatus shown in FIG. In FIG. 24B, the projection optical system 14 usually has an aperture stop 16 inside, and regulates the angle θa at which light passing through the reticle 8 can pass, and the angle of light rays falling on the wafer 15. θ is determined.

Generally, the numerical aperture NA of a projection optical system is an angle defined by NA = sin θ, and when the projection magnification is 1 / m, the relationship is sin θa = sin θ / m. In this type of apparatus, it is common that the image plane is telecentric, that is, the principal ray falling on the image plane is perpendicular to the image plane. In order to satisfy the condition of this “image plane telecentric”, FIG. A real image of the exit surface of the homogenizing optical system 19, that is, the light source surface of the secondary light source 24 is formed at the position of the aperture stop 16 in FIG.

Under these conditions, a solid angle when the secondary light source surface is viewed from the reticle 8 through the second condensing optical system 20 is taken as a range of light incident on the reticle 8, and a half angle thereof is φ.
And the coherency σ of the illumination light is σ = sinφ / sin
When defined by θa, it was considered that the pattern formation characteristics were determined by NA and σ.

Next, the relationship between NA and σ and the pattern forming characteristics will be described in detail. The larger the NA, the higher the resolution, but the shallower the depth of focus, and it becomes difficult to secure a wide exposure area due to the aberration of the projection optical system 14. Without a certain exposure area and a certain depth of focus (for example, 10 mm square, ± 1 μm), it cannot be used for actual LSI manufacturing and the like, so that the conventional apparatus has a limit of about NA = 0.35. On the other hand, the σ value is mainly related to the pattern cross-sectional shape and the depth of focus, and is related to the resolution in correlation with the cross-sectional shape. When the σ value is small, the edge of the pattern is emphasized, so the cross-sectional shape becomes a good pattern shape with the side wall approaching perpendicular,
The resolution of a fine pattern deteriorates, and the focus range that can be resolved is narrowed. Conversely, when the σ value is large, the resolution in a fine pattern and the focus range that can be resolved are slightly improved. However, in the case of a thick resist, the cross section of the pattern is trapezoidal or triangular in the case where the pattern cross section is inclined slowly.

For this reason, in a conventional projection exposure apparatus, a relatively balanced σ value is fixedly set to σ = 0.5 to 0.7, and is experimentally set to σ = 0.3. Is only being attempted. Since the size of the light source surface of the secondary light source 24 may be determined to set the σ value, generally, the circular aperture stop 9 for setting the σ value is provided immediately after the light source surface of the secondary light source 24.
Is placed.

As one method for improving the depth of focus of such a general projection exposure apparatus, there has been proposed an example in which a special aperture having a special aperture pattern is used instead of the circular aperture stop 9 (Ukita and Tsujiuchi). Research on Microscope Objectives (10th Report), Report of the Mechanical Testing Laboratory, 1957, 11th
Vol. 2, No. 9, p9-). Among them, what is characteristic is that when the filter shown in FIG. 25A is used, an extremely high resolution performance is obtained for the L / S patterns arranged in the direction perpendicular to the direction connecting the two light transmission regions. Is described.

On the other hand, as a modified example, a filter having four openings (hereinafter referred to as a fourth filter) as shown in FIG. 25B has been proposed (Japanese Patent Publication No. 56-9010).
Publication), the projection exposure using the fourth filter of this form was described by Kamon and Miyamoto et al. In “The reduced projection exposure method using a deformed light source” at the 52nd Annual Meeting of the Japan Society of Applied Physics in October 1991. (I), (II) "(lecture numbers 12a-ZF-3 and 12a-ZF-4). According to this, it is shown that high resolution performance for L / S can be obtained not only in one direction but also in a direction perpendicular thereto.

FIG. 26 shows the results of simulating the transfer characteristics in the case of illumination by the fourth filter and in the case of normal illumination. The horizontal axis is the L / S pattern size where the ratio of line to space is 1: 1, and the vertical axis is the depth of focus (D
OF). The exposure wavelength is 365 nm (i-line),
The NA of the projection optical system is 0.55. Also, a resist that can be resolved with an image contrast of 70% or more is assumed.
In such an L / S pattern, L / S <0.6
At 5 μm, especially around L / S = 0.4 μm, the effect of improving the resolution and the depth of focus by the fourth illumination is remarkable as compared with the normal illumination. However, when L / S ≧ 0.65 μm, on the contrary, the depth of focus in the case of the normal illumination is larger than that of the fourth illumination.

In particular, the depth of focus around L / S = 0.7 μm is the worst. This characteristic depends on the eye position and size of the fourth filter. As the distance between the eyes increases, the focal depth of the small L / S improves, while the focal depth at the large L / S significantly decreases. Also, there is a tendency that as the eyes are smaller, only the focal depth of the L / S pattern of a specific size is improved. As described above, although there are some differences depending on the eye position and size of the fourth filter, the overall tendency is as shown in FIG.

Although the above description has been made with respect to the L / S pattern, it can be understood that the fourth filter has a rather opposite effect when the isolated pattern is formed (when a positive resist is used), and the DOF is reduced. Was. Depth of focus 1.5
The minimum line width that can secure μm is 0.4 mm for normal exposure.
.mu.m, while exposure with the fourth illumination is 0.1 .mu.m.
It becomes 45 μm. That is, when performing exposure by the fourth illumination, the 1: 1 L / S pattern is 0.29.
μm, while the isolated pattern is 0.4
This means that it is necessary to design with a thickness of 5 μm or more.
In an actual LSI pattern, although there are few typical isolated cutout patterns in which the cutout line width is close to the design rule and both sides are resist over several μm, a pattern with a small ratio of space to line is very small. Many In the case of such a so-called isolated pattern, the line width at which the depth of focus of 1.5 μm or more can be ensured becomes large, which greatly affects the shrinkage of the chip.

In the fourth exposure using the fourth filter, good resolution performance cannot be obtained for patterns arranged in directions other than two directions orthogonal to each other. It was found that the resolution of the obtained pattern was remarkably reduced. The characteristic shown in FIG. 26 is a case where the fourth filter and the direction of L / S have a relationship as shown in FIG. When the fourth filter and the direction of L / S have a relationship as shown in FIG. 28, that is, when the direction of L / S is 45 degrees, the result as shown in FIG. 29 is obtained. In this case, the transfer with the fourth illumination has a lower depth of focus than the normal illumination.

[0018]

As described above, in the conventional exposure using the fourth filter as compared with the exposure using the ordinary circular secondary light source, the effect of improving the resolution and the depth of focus is obtained when L / S <0.65 μm. Remarkable. However, L / S ≧ 0.6
Conversely, at 5 μm, the depth of focus in the case of normal illumination is larger than that of the fourth illumination. In particular, L / S = 0.
In the vicinity of 7 μm, the depth of focus is about 1.5 μm. Therefore, when a layer requiring a large depth of focus is transferred, a pattern near L / S = 0.7 μm is not transferred well. That is, 2.5 μm near L / S = 0.4 μm
Despite having a depth of focus of about m, there is a problem that the transfer characteristics are limited by a pattern of a larger size.

Further, when a filter that transmits light only at specific four points, such as a fourth filter, is used as an illumination filter, there is a problem that a large difference occurs in resolution performance depending on the direction of a pattern.

In the above conventional example, the depth of focus and the resolution of the L / S are improved, while the depth of focus and the resolution are reduced in the isolated pattern. This means
This indicates that the larger the line width with respect to the space width of the pattern, the more the line width needs to be designed. Actual L
In the SI pattern, since there are many patterns having a large line width with respect to a space, the effect of a large depth of focus by the fourth illumination cannot be linked to the chip size shrink.

The present invention has been made in consideration of the above circumstances, and has as its object the purpose of making it possible to sufficiently increase the depth of focus even when the size of the L / S pattern is large. An object of the present invention is to provide a projection exposure apparatus capable of improving the image quality. Another object of the present invention is to provide a projection exposure apparatus capable of sufficiently increasing the depth of focus regardless of the direction of a pattern.

Another object of the present invention is to make it possible to design the isolated line width of an isolated pattern or an isolated pattern having a large line width with respect to the space width more finely. As a result, the chip size can be reduced. An object of the present invention is to provide a projection exposure apparatus which achieves a large shrink.

[0023]

In order to achieve the above object, the present invention employs the following configuration.

[0024]

[0025]

[0026]

That is , according to the present invention (claim 1 ), in a projection exposure apparatus for projecting and exposing a pattern of a mask onto a wafer via a projection optical system, an intensity distribution in an emission plane of the light source is used as a light source for illuminating the mask. A special stop is provided that is four times symmetrical with respect to the optical axis and increases the intensity in four regions deviated from the optical axis, and a substrate having a light-transmitting property with respect to exposure light is arranged at the pupil position of the projection optical system. The thickness or the refractive index of the substrate has a distribution.

Here, in the substrate disposed at the pupil position of the projection optical system, it is desirable that the thickness or the refractive index of the substrate corresponding to the peripheral portion of the pupil be made different from other portions. In addition to the above configuration, it is more preferable to use the halftone mask, the self-alignment type phase shift mask or the shifter-edge type phase shift mask.

Further, the present invention (claim 2 ) provides a first condensing optical system for condensing light from a light source, and a homogenizing optical system for homogenizing the light condensed by the first condensing optical system. System, and a special stop provided at the light source surface position on the emission side of the homogenizing optical system,
A second condensing optical system for condensing light obtained through the special aperture and irradiating the mask with the light; and a projection optical system for projecting light transmitted through the mask onto a wafer, and formed on the mask. In a projection exposure apparatus that transfers a pattern onto a wafer, as a special stop, there is a center of a substantially figure on a concentric circle centered on the optical axis, and the intensity distribution in the light source plane is symmetrical four times with respect to the optical axis. In addition, it is configured to have four relatively wide radial directions that increase the strength in four regions deviated from the optical axis, and a relatively narrow radial direction that connects these four regions. It is characterized by the following.

According to the present invention (claims 3 to 5 ), in a projection exposure apparatus for projecting and exposing a pattern of a mask onto a wafer via a projection optical system, a light source for illuminating the mask is provided.
The intensity distribution in the emission plane of the light source is increased four times in four regions symmetrical with respect to the optical axis, and the intensity is increased in four regions deviated from the optical axis, and the intensity of the central portion of the light source is increased. , A halftone mask, a self-alignment type phase shift mask or a shifter-edge type phase shift mask.

According to the present invention (claim 6 ), in a projection exposure apparatus for projecting and exposing a pattern of a mask onto a wafer via a projection optical system, the intensity distribution of a light source for illuminating the mask may be deviated from one optical axis. The intensity is increased in the region or two regions symmetrical with respect to the optical axis, and the transmittance distribution of the pupil of the projection optical system is transmitted along the pupil diameter direction including the region where the intensity of the light source is large on the pupil. In this method, the intensity distribution of the light source and the transmittance distribution of the pupil are synchronously rotated around the optical axis during exposure.

According to the present invention (claim 7 ), in a projection exposure apparatus for projecting and exposing a pattern of a mask onto a wafer via a projection optical system, the intensity distribution of a light source for illuminating the mask is set at 4 degrees with respect to the optical axis. The intensity is increased in four regions that are symmetrical and deviated from the optical axis, and the transmittance distribution of the pupil of the projection optical system is
On the pupil, the transmittance is increased in the side direction or diagonal direction of a rectangle composed of four regions where the intensity of the light source is large, and the intensity distribution of the light source and the transmittance distribution of the pupil are synchronously rotated about the optical axis during exposure. It is characterized by the following.

[0033]

[0034]

According to the present invention (claim 1) , a fourth filter is used as a light source, and a substrate having transparency to exposure light is arranged at a pupil position of the projection optical system. By making the thickness or the refractive index of the substrate corresponding to the portion different from that of the other portions, it is possible to obtain a large depth of focus and an effect of improving the limit resolution independently of the pattern size. In addition, by using a halftone mask or a phase shift mask as the mask, the above effect can be further enhanced.

According to the present invention (claim 2 ), the special stop as a light source has two types of filters, an annular illumination filter and a fourth illumination filter.
As a result, the disadvantages of the two cancel each other out, and the dependence of the pattern size and direction can be reduced to a level at which there is no practical problem, and a high resolution performance and an effect of improving the depth of focus can be obtained.

According to the present invention (claims 3 to 5 ),
As described in claims 1 to 3, the L / S pattern in the case of transferring by an illumination method in which the light source intensity distribution is point-symmetric with respect to the optical axis and the intensity in four regions off the optical axis is large. By increasing the light source intensity near the center of the light source, in addition to the depth of focus and the effect of improving the limit resolution, the depth of focus and the resolution of the isolated pattern can also be improved. As a result, it is possible to achieve a large shrink of the chip size.

According to the present invention (claims 6 and 7 ),
By disposing a filter having an aperture at a position decentered from the optical axis at the light source position of the exposure apparatus and using an illumination optical system for illuminating the mask obliquely, a long L / S pattern in a direction perpendicular to the eccentric direction is obtained. Higher order diffracted light enters the projection optical system, and the resolving power is improved. Here, since an actual LSI has various directions, high-order diffracted light generated from a pattern other than the above-mentioned direction does not enter the pupil, and the resolution is not improved. Therefore, by arranging a slit having the eccentric direction of the filter in the longitudinal direction at the pupil position, diffracted light generated from a pattern other than the above direction is positively cut. Further, by exposing the slit and the filter while rotating the slit and the filter in 360 degrees around the optical axis,
It is possible to eliminate the pattern direction dependence of the resolution.

Further, by using filters having a total of two apertures, one each at a position decentered from the optical axis and symmetric with respect to the optical axis, as a filter disposed at the light source position, It is possible to have the same resolution and halve the exposure time. Further, as a filter disposed at the light source position, a filter which is four-fold symmetrical with respect to the optical axis and increases the intensity in four regions off the optical axis is used. By using a slit filter for increasing the transmittance, it is possible to have substantially the same resolution as that of the above-described exposure method, and to further shorten the exposure time.

[0039]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the illustrated embodiments.

FIG. 1 is a schematic diagram showing a projection exposure apparatus according to a first embodiment of the present invention. In FIG. 1, 1 is a lamp (light source), 2 is an elliptical reflecting mirror, 3 is a second focal point of the elliptical reflecting mirror 2, 4 is an input lens, 5 is an optical integrator, 6 is an output lens, 7 is a collimation lens, and 8 is A reticle, 9 'is a special aperture having a distribution in transmittance, 10 is a filter, 11 and 12 are cold mirrors, 13 is a lamp house, 14 is a lens, a mirror, or a combination thereof, and an image of a pattern on the reticle 8 is formed on a wafer. A projection optical system for projecting, 15 is a wafer, 16 is a stop for determining a numerical aperture, and is called a pupil. This is a filter having a distribution in the optical path length.

Using a mercury lamp as the light source lamp 1, g
Bright lines such as a line 436 nm, an h line 405 nm, and an i line 365 nm, or a continuous spectrum near these wavelengths are extracted and used. For this reason, the lamp 1 as the light source needs to have high luminance, and it is better to be close to a point light source in consideration of the light collection efficiency and irradiation uniformity. However, since such an ideal light source does not exist in practice, a lamp 1 having a finite size and a distribution of intensity must be used, and the light emitted from such a lamp 1 cannot be reduced. An issue is how to convert the light into light with good efficiency and uniform irradiation.

In the apparatus shown in FIG. 1, the lamp 1 is placed at the first focal point of the elliptical reflecting mirror 2, and the light beam is once collected near the second focal point 3 of the elliptical reflecting mirror 2. Then, the light beam is converted into a substantially parallel light beam by the input lens 4 which shares a substantially focal position with the second focal point 3, and is input into the optical integrator 5.
The optical integrator 5 is a bundle of a number of rod-shaped lenses, and is also called a fly-eye lens. Passing through the optical integrator 5 is a main factor for improving the irradiation uniformity, and the input lens 4 plays a role in reducing vignetting of the light beam passing through the optical integrator 5 and improving the light collection efficiency.

The light exiting the optical integrator 5 is
By the output lens 6 and the collimation lens 7, the light beams emitted from the respective small lenses of the optical integrator 5 are collected so as to be superimposed on the reticle 8. Although the light beam incident on the optical integrator 5 has an intensity distribution depending on the location, the light emitted from each small lens of the optical integrator 5 is superimposed almost equally, so that the irradiation intensity on the reticle 8 becomes almost uniform. As a matter of course, if the intensity distribution of the light incident on the optical integrator 5 is close to uniform, the illuminance distribution of the reticle 8 on which the emitted light is superimposed becomes more uniform. On the emission side of the optical integrator 5, a special stop 9 ′ described later is arranged, and determines the size of the optical integrator 5 on the emission side.

When a mercury lamp is used as the lamp 1 and the light is condensed by the elliptical reflecting mirror 2, the structure of the mercury lamp is vertically elongated as shown in FIG. I can't take it out. Therefore, as shown in FIG. 1, the intensity distribution of light entering the central portion of the optical integrator 5 may be reduced only by using a convex lens as the input lens 4. Therefore, a biconvex or one-sided convex / concave conical lens may be inserted between the input lens 4 and the optical integrator 5 to make the intensity distribution of light entering the optical integrator 5 more uniform.

The filter 10 is for passing only light having a wavelength whose optical system has been aberration-corrected. The cold mirrors 11 and 12 bend the optical path to reduce the height of the apparatus and to reduce long-wavelength photothermal rays. It plays the role of transmitting the light and absorbing it into the coolable portion of the lamp house 13. The light irradiated on the reticle 8 passes through the projection optical system 14, and the image of the fine pattern on the reticle 8 is projected and transferred to the resist on the wafer 15.

FIG. 2 is a plan view showing the aperture pattern of the fourth filter 20 as the special stop 9 'used in the apparatus of this embodiment. In this figure, hatched portions indicate light-shielding portions 23, and four circular openings (light transmitting portions) 22 are symmetrical four times with respect to the optical axis 21 and are arranged at positions shifted from the optical axis. As the mask 8, a halftone mask described later was used.

FIG. 3 shows the result of calculating the focus margin for the pattern size in the exposure with the fourth filter in this embodiment. A dotted line indicates exposure when a normal Cr mask is transferred by normal illumination (σ value 0.6), a solid line indicates exposure when a normal Cr mask is used at the fourth illumination, and a dashed line indicates fourth illumination. Further, the exposure is performed when a halftone mask is used (this embodiment). The NA of the exposure apparatus is 0.55, and the exposure wave λ is 365 nm.

By performing the fourth illumination and further using a halftone mask, it can be seen that the depth of focus at all line widths is uniformly improved. L / S = having maximum depth of focus around 0.4 μm, L / S = 0.7 μm
The fact that the depth of focus becomes minimal near m is the same as when a normal Cr mask is used, but since the depth of focus as an absolute value is improved, even in a pattern having a large L / S size, A practically sufficient depth of focus is obtained.

FIGS. 4 to 6 are views for explaining the mask 8 used in the apparatus of this embodiment. FIG. 4A shows a typical cross-sectional structure of a halftone mask, FIG. 4B shows a light amplitude distribution, and FIG. 4C shows a light intensity distribution. The halftone mask is made of a light-transmitting substrate 30 (usually Si
On O ₂ ), an LSI pattern is formed by a film 31 that is translucent (1% ≦ amplitude transmittance ≦ 30%) with respect to exposure light. The thickness of the translucent film 31 is 180 × (2n + 1) degrees ± 30 ( degrees ), where n is an integer, with respect to the phase of the transmitted light 32 of the substrate.

The relationship is controlled so as to satisfy the following relationship. The substrate transmitted light 33 is diffracted and spread on the wafer.
Although the profile as shown in, the light 32 transmitted through the translucent film 31 is on the wafer to become opposite in phase (profile A), to improve the mutual image contrast weakened by interference (profile C).

Further, in the above embodiment, it was shown that the effect of exposing the halftone mask by the fourth illumination filter was great. However, other phase shift masks such as a shifter-edge type phase shift mask and a self-aligned type Even if a shift mask is used, a great effect similarly occurs. FIG. 5 shows a typical sectional structure of a shifter-edge type phase shift mask. In the shifter-edge type phase shift mask, an LSI pattern is formed on a translucent substrate 30 (usually SiO ₂ ) by using a substance 34 (SiO ₂ ) transparent to exposure light. The thickness of the transparent film 34 is
Is 180 × (2n + 1) degrees ± 30 ( degrees ) with respect to the phase of the substrate transmitted light 33: n is an integer,

The relationship is controlled so as to satisfy the following relationship. Since the light transmitted through the substrate 33 and the light 35 transmitted through the transparent film 34 have opposite phases on the wafer, the portions corresponding to the edges of the transparent film 34 interfere with each other to form a dark portion. Transparent film 3
Since the line width of No. 4 is small, the dark portions at the two edge portions overlap to form one dark portion.

FIG. 6 shows a typical sectional structure of a self-alignment type phase shift mask. The self-aligned phase shift mask is formed on a light-transmitting substrate 30 (usually SiO ₂ ) by using an LSI (Cr or the like) which is opaque to exposure light.
A pattern is formed. A phase shifter 37 is provided around the opaque film 36 using a material (SiO ₂ or the like) transparent to exposure light. The thickness of the phase shifter 37 is such that the phase of the transmitted light 38 is 180 × (2n + 1) degrees ± 30 ( degrees ) with respect to the phase of the substrate transmitted light 33: n is an integer,

Is controlled so as to satisfy the following relationship. In this embodiment, the above-described optical principle is achieved by the above-described structure. However, this structure does not limit the present invention, and another mask structure that achieves the above-described optical principle may be used.

As described above, according to this embodiment, the fourth filter 20 as shown in FIG. 2 is used to determine the shape of the light source, and various phase shift masks as shown in FIGS. By using, L / S of all sizes
The effect of improving the DOF of the pattern can be increased.
For this reason, even when the size of the L / S pattern is large, the depth of focus can be made sufficiently large, and the pattern exposure accuracy can be improved.

Next, a second embodiment of the present invention will be described. This embodiment uses a fourth + pupil filter. The fourth filter for determining the shape of the light source is the same as that shown in FIG. 2. In addition, in the present embodiment, the pupil position 16 of the projection optical system 14 shown in FIG.
The phase filter 40 as shown in FIG.

The phase filter of FIG. 7A has a disk shape that is rotationally symmetric with respect to the optical axis 41, and its diameter corresponds to the pupil diameter. The material is transparent to the exposure light, and for example, SiO ₂ is used. In the annular zone area 42 having the inner diameter r and the width d, the plate thickness is larger by t than the other areas 43. That is, it means that the optical path length of the light passing through the area 42 is longer than that of the area 43. This difference in optical path length causes a light phase difference. r, d and t are determined depending on the line width for which the depth of focus is desired to be improved, the position of the fourth filter, and the like. In this embodiment, FIG.
Although the phase filter having the thickness distribution shown in the above is used, the present invention is not limited to this, and the shape of the phase filter can be changed depending on the line width and line type for which it is desired to improve the depth of focus.

Also, the phase filter shown in FIG. 7B produces the same effect as the above-mentioned phase filter. FIG.
The difference from (a) is that the plate thickness in the annular zone 42 having the inner diameter r and the width d is smaller by t than the other zones 43. That is, it means that the optical path length of the light passing through the area 42 is shorter than that of the area 43.
Since the phase difference of the light caused by the difference in the optical path length is 2π as one cycle, a desired phase difference can be obtained in any of the structures shown in FIGS. 7A and 7B.

FIG. 8 shows a result of calculating a focus margin for a pattern size in exposure using the fourth filter 20 having four openings and the phase filter 40. The dotted line indicates the normal exposure (exposure using only the fourth filter), the solid line indicates the exposure (the fourth filter + pupil filter) according to the present embodiment when a normal Cr mask is used, and the one-dot chain line uses the halftone mask. Exposure (fourth filter + pupil filter + halftone mask) according to the present embodiment. The NA of the exposure apparatus was 0.55, the coherence factor σ was 0.6, and the exposure wavelength λ was 365 n.
m.

When the phase filter 40 is inserted at the pupil position, the effect of improving the depth of focus is increased when L / S ≧ 0.65 μm, and the problem in the case of exposing only with the fourth illumination is solved. . Further, it can be seen that the effect is even greater when the halftone mask shown in FIG. 4 is used.
Also, the self-aligned mask and the shifter edge shown in FIGS. Also, since the amplitude transmittance of the pupil function is 100%, one of the problems of the superflex method is that the filter absorbs the exposure light and turns into heat, causing the optical system to thermally expand and deteriorating the transfer accuracy. The problem does not arise. Next, a third embodiment of the present invention will be described. This embodiment uses a fourth + annular filter.

In this embodiment, the shape of the special stop 9 'on the secondary light source surface shown in FIG. 1 is as shown in FIG.
51 is an optical axis, 52 is a light transmitting part, and 53 is a light shielding part. This is because the circular light transmitting portions A, B, C, and D each having a wide area in the radial direction around the optical axis are ring-shaped light transmitting portions E having a narrow area in the radial direction. Are tied together.

Further, in FIG. 9, although all are constituted by the boundaries constituted by the curves, they do not necessarily have to be the curves, and
The second shape shown at 0 may be the special stop 9 '. Further, the third shape of the special aperture 9 'may be the shape shown in FIG. 11 without departing from the scope of the present invention. A feature of the shape shown in FIG. 11 is that a wide area in the radial direction does not have a uniform width, and that the connection is intermittent. In FIG. 11, the portions from A to A are light transmitting portions.

Further, in the shape of the embodiment shown in FIGS. 9 to 11, the light transmittance of the light transmitting portion 52 is not necessarily required to be 100%. It doesn't even have to be a rate. Also, there is no necessity of being point-symmetric. In this embodiment, the light transmitting section 52
Can be appropriately changed depending on the resolution performance and dimensional accuracy of a desired pattern.

FIGS. 12 and 13 show exposure characteristics when exposure is performed using the special filter shown in FIG. FIG.
2 shows the characteristics for the vertical and horizontal L / S patterns, and FIG. 13 shows the characteristics for the oblique L / S patterns. The vertical axis indicates the depth of focus when the resist contrast is 70%, and the horizontal axis indicates the L / S pattern size.

Assuming that the depth of focus necessary for transferring the actual device pattern is 1.5 μm, the L / S pattern size that can secure the required depth of focus is 4 from the conventional example shown in FIG.
There is almost no deterioration as compared with the case where a special filter having two openings is used. That is, in the case of the conventional example, L / S ≧ 0.3μ
m, whereas L / S = 0.32 μm in this embodiment.
m.

On the other hand, in the oblique L / S pattern shown in FIG. 13, according to the exposure in the conventional example, the pattern size capable of securing the required depth of focus is L / S ≧ 0.7 μm, and the oblique L / S is very large. It turns out that it is necessary to design thick.
In contrast, in the exposure according to the present embodiment, L / S ≧ 0.
The required depth of focus can be secured at 55 μm, which is comparable to the case of normal exposure (L / S ≧ 0.5 μm). That is, according to the present embodiment, the exposure characteristics in the vertical and horizontal directions are oblique L / L while maintaining the excellent resolution characteristics when a special filter having four conventional aperture masks is used.
Even in S, the resolution characteristics are not significantly deteriorated, and the oblique L /
The design rule of the S pattern can be greatly reduced.

The circular opening ABCD of the special filter of FIG.
The characteristics shown in FIGS. 12 and 13 vary depending on the radius, center position, width, inner diameter, and outer diameter of the ring-shaped region E. Need to optimize as needed.

As described above, according to the present embodiment, the use of the special filter having the fourth and annular zones has a high resolution performance and an effect of improving the depth of focus, and also has an effect on the pattern size and direction which could not be obtained conventionally. Has the effect of reducing the dependence on the practically acceptable level. When the halftone mask, the self-alignment type mask, and the shifter edge type mask shown in FIGS. 4 to 6 are used as the mask, the effect of increasing the depth of focus is further increased.

Next, a fourth embodiment of the present invention will be described. In this embodiment, a fifth filter and a halftone mask are used in combination with the fifth filter. Basically, it is similar to the first embodiment.
The third filter 60 is as shown in FIG.
61 is an optical axis, 62 is a light transmitting part, and 63 is a light shielding part. In addition to the four openings A, B, C, and D that are four-fold symmetrical with respect to the optical axis 61 and deviated from the optical axis, an aperture E near the optical axis 51 is provided.
Having.

FIGS. 15 and 16 show the results of exposing a normal Cr mask and a halftone mask using such a filter 60. FIG. FIG. 15 shows the effect of improving the resolution and the depth of focus for an L / S pattern having a line-to-space ratio of 1: 1. The horizontal axis is the pattern size,
The vertical axis indicates the depth of focus (DOF). The exposure wavelength is 365 nm (i-line), and the NA of the projection optical system is 0.55.

As described above, in the L / S pattern, 5
The effect of improving the depth of focus by the fourth illumination exposure is lower than that by the fourth illumination exposure. However, the minimum line width at which the focal depth of 1.5 μm can be ensured is almost the same as in the case of the fourth illumination exposure, and has no adverse effect on the chip size shrink. Further, by using a halftone mask, the effect of increasing the depth of focus can be further increased.

FIG. 16 shows the result of calculating the depth of focus with respect to the pattern size of the isolated pattern. 4
It can be seen that the depth of focus is improved by performing the fifth illumination exposure as compared with the case where the exposure is performed by the fifth illumination. Further, it can be seen that the depth of focus is further improved by using the halftone mask. The line width at which the focal depth of 1.5 μm can be ensured is 0.45 μm in the case of the normal Cr mask exposure using the fourth illumination, and is reduced to 0.41 μm in the halftone mask exposure using the fifth illumination. It turns out that it is possible. Further, it is possible to further improve the depth of focus by optimizing the size of the aperture.

In other words, the fifth illumination exposure makes it possible to design the minimum line width of 1: 1 L / S to be small (about 0.3 μm) while maintaining the advantage of the fourth illumination exposure. It has become possible to design a narrower line width of the punch pattern. As a result, it is possible to design a so-called isolated pattern having a large line width with respect to a large space width in an LSI pattern so as to have a narrower line width, and to achieve a large chip size shrink. It became.

The present invention is not limited to the above-described embodiments, but can be implemented in various modifications without departing from the scope of the invention. In the example, 4
As means for achieving the fifth and fifth illuminations, FIG.
Although the special stop shown in FIG. 4 was used, the present invention is not limited to this.
It is possible to achieve double-eye lighting.

Next, a fifth embodiment of the present invention will be described. FIG. 17 is a schematic configuration diagram showing a projection exposure apparatus according to the fifth embodiment of the present invention. Light generated from the light source 71 is condensed by the first condensing optical system 72 and guided to the uniforming optical system 73. As the homogenizing optical system 73, an optical fiber, a polyhedral prism, or the like may be used. The light exiting the homogenizing optical system 73 forms an image to form a secondary light source. A filter 4 having an aperture 81 at a position decentered from the optical axis at the position of the secondary light source (hereinafter, referred to as a first decentered filter)
Is installed. The exposure light passes only through the aperture 81 and illuminates the reticle 76 through the second condensing optical system 75.

The exposure light having passed through the reticle 76 reaches the wafer 79 by the projection optical system 77. Projection optical system 7
The pupil 78 existing in the pupil 7 is usually a circular aperture, but in the present embodiment, a slit-shaped filter (hereinafter referred to as a pupil slit filter) is provided at the pupil position as shown in the figure. The longitudinal direction of this slit is the same as the eccentric direction of the first eccentric first filter 74. The first eccentric first filter 74 and the pupil slit filter 78 can be synchronously rotated by the synchronous rotation control circuit 80 and a motor (not shown) while maintaining the above-described positional relationship. One exposure is completed by rotating the first eccentric first filter 74 and the pupil slit filter 78 by 360 degrees by the synchronous rotation control circuit 80.

FIG. 18 shows the result of calculating the focus margin for the pattern size in the exposure by the projection exposure apparatus of this embodiment. The dotted line indicates normal exposure (σ = 0.
6), the solid line indicates exposure according to the embodiment when a normal Cr mask is used. The NA of the exposure apparatus, the coherence factor σ, and the exposure wavelength λ are 0.55, 0.6,
365 nm. The result of FIG. 18 does not depend on the direction of L / S. Therefore, this embodiment solves the above-mentioned problem,
It can be seen that the direction dependency of L / S is eliminated, and that the depth of focus is dramatically increased as compared with the normal exposure. Further, as the eccentric distance of the center of the aperture 81 from the optical axis increases, the focal depth of fine L / S improves.

As described above, according to this embodiment, the aperture 81 is located at a position decentered from the optical axis at the secondary light source position of the exposure apparatus.
Is disposed, and the illumination optical system illuminates the mask 76 obliquely, so that the high-order diffracted light of the L / S pattern long in the direction perpendicular to the eccentric direction is projected onto the projection optical system 77
And the resolution is improved. Moreover, by disposing a slit in which the eccentric direction of the filter is aligned with the longitudinal direction at the pupil position, the diffracted light generated from a pattern other than the above direction is positively cut, and the slit and the filter are rotated about the optical axis. Exposure while rotating synchronously by 360 degrees makes it possible to eliminate the pattern direction dependency of the resolving power.

According to the present embodiment, the pupil slit filter 78 is provided with a translucent portion for attenuating the zero-order diffracted light as shown in FIG. 19, so that the resolution can be further improved. Light emitted from the first eccentric first filter 74 illuminates the mask 76 obliquely as shown in FIG.
In the case of a 1: 1 L / S pattern, the transmitted light of the mask 76 is diffracted and mainly split into ± 1st order diffracted light and 0th order diffracted light. 0
The next light goes straight and reaches the point a of the pupil slit filter 78. The + 1st-order diffracted light reaches point b. The -1st-order diffracted light does not enter the pupil and does not participate in imaging. Since the 0th-order light is larger than the + 1st-order diffracted light, the resolution can be further increased by attenuating the light by the translucent film 85. In this embodiment, the translucent film 85 is used, but any means for attenuating only the zero-order light may be used.

FIG. 20 is a schematic configuration diagram showing a sixth embodiment of the present invention. The same parts as those in FIG. 17 are denoted by the same reference numerals, and detailed description thereof will be omitted. This embodiment differs from the fifth embodiment in the shape of the light source filter mounted on the secondary light source.

That is, the light source filter in this embodiment is provided with two apertures 81 and 82 at target positions with the optical axis interposed therebetween (hereinafter, referred to as a second filter). According to this embodiment, the resolution characteristic is the same as that of the fifth embodiment, but one exposure is performed by the synchronous rotation control circuit 80 by the second filter 74.
And the end by rotating the pupil slit filter 78 by 180 degrees. If the light amount from the aperture 81 in the fifth embodiment is equal to the light amount from one aperture in the present embodiment, the number of apertures becomes two and the rotation angle becomes half, so that the exposure time can be reduced by half. it can.

FIG. 21 is a schematic diagram showing a seventh embodiment of the present invention. The same parts as those in FIG. 17 are denoted by the same reference numerals, and detailed description thereof will be omitted. This embodiment differs from the sixth embodiment in the shape of the light source filter mounted on the secondary light source and the shape of the filter mounted on the pupil position.

That is, the light source filter in this embodiment has four apertures 81, 82,
83 and 84 (hereinafter, referred to as a fourth filter). Also, the filter at the pupil position has a grid-like aperture (hereinafter, referred to as a pupil grid filter). The shape of the filter at the pupil position may be any opening that connects the fourth at the pupil position, and the opening provided along the direction of the side of the fourth rectangle, such as the above-mentioned girder, Or 4
An opening provided in the second diagonal direction (in this case, a cross-shaped opening) may be used.

According to this embodiment, the resolution characteristic is almost the same as that of the fifth embodiment, but one exposure is performed by the synchronous rotation control circuit 8.
The end is different by rotating the fourth filter and the pupil digit filter by 90 degrees at 0. If the amount of light from the aperture of the fifth embodiment is equal to the amount of light from one aperture in the present embodiment, the number of apertures becomes four and the rotation angle image becomes 1/4, so that the exposure time is reduced to 1/4. can do.

In the fifth to seventh embodiments, a slit-shaped or cross-shaped filter is provided at the pupil position of the projection optical system. At the light-shielding portion of this filter, the exposure light is absorbed and converted into heat. There is a problem that the optical system is deteriorated and the transfer accuracy is greatly affected. FIG. 22 shows a specific configuration of a pupil filter for solving the above-described problem particularly in the fifth and sixth embodiments. The figure shows the configuration of the pupil slit filter. Reference numeral 91 denotes a slit, and 92 denotes a mirror having an inclination. When the exposure light enters the pupil slit filter from above, the exposure light incident on the inclined mirror 92 is reflected without being absorbed. The reflected exposure light is guided to the outside of the optical system and is absorbed by an absorber provided outside the optical system. Therefore, since the exposure light does not change into heat in the optical system, the transfer accuracy does not deteriorate.

In the fifth to seventh embodiments, by applying a halftone phase shift mask as a mask, the depth of focus and the resolving power can be further improved. The dashed line in FIG. 18 indicates the transfer characteristics when the transfer is performed using a halftone mask in addition to the three embodiments. It can be seen that the depth of focus is improved as compared with the case where a normal Cr mask is used.

In the above example, the effect of exposing the halftone mask by the fourth illumination filter and the phase filter is large. However, other phase shift masks such as a shifter edge type phase shift mask and a self-alignment type The use of a phase shift mask also provides a great effect. Further, another mask structure that achieves the above optical principle may be used.

In the fifth to seventh embodiments, at least one eccentric lens from the optical axis is used to determine the shape of the secondary light source.
Although a filter having one aperture is used, the present invention is not limited to this, and another method such as a fiber may be used.

[0089]

[0090]

As described above, the present invention (claim 1)
According to the method, by using a fourth filter as a secondary light source and arranging a phase filter at the pupil position of the projection optical system, a large depth of focus can be achieved regardless of the pattern size.
The effect of improving the limit resolution can be obtained. In addition to this
By using a halftone mask or a phase shift mask as the mask, the above-mentioned effect can be further enhanced.

Further, according to the present invention (claim 2 ), a special diaphragm having both types of filters, ie, an annular illumination filter and a fourth illumination filter, is used as a secondary light source, so that a pattern is formed. The dependence on size and direction can be reduced to a level that does not cause any practical problems, and high resolution performance and an effect of improving the depth of focus can be obtained.

According to the present invention (claims 3 to 5 ),
In addition to the effect of improving the depth of focus of the L / S pattern and the limit resolution when exposing using the fourth filter as the secondary light source as described in claims 1 to 3, the light source intensity near the center of the secondary light source is also improved. By increasing the depth, the depth of focus and the resolving power of the isolated pattern can also be improved. As a result, it is possible to achieve a large shrink of the chip size. The present invention (claims 6 and 7 )
According to the method, by synchronously rotating the secondary light source having the eccentric aperture and the pupil filter, it is possible to sufficiently increase the depth of focus regardless of the direction of the pattern.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a projection exposure apparatus according to a first embodiment of the present invention;

FIG. 2 is a plan view showing a configuration of a fourth filter according to the first embodiment;

FIG. 3 is a characteristic diagram showing a relationship between L / S size and DOF in the first embodiment.

FIG. 4 is a view showing a typical cross-sectional structure of a halftone mask;

FIG. 5 is a view showing a typical cross-sectional structure of a shifter-edge type phase shift mask;

FIG. 6 is a view showing a typical sectional structure of a self-alignment type phase shift mask;

FIG. 7 is a perspective view showing a schematic configuration of a phase filter used in a second embodiment;

FIG. 8 is a characteristic diagram showing a relationship between L / S size and DOF in the second embodiment;

FIG. 9 is a diagram showing a configuration of a fourth filter having an annular zone used in the third embodiment;

FIG. 10 is a diagram showing another example of a fourth filter having an annular zone.

FIG. 11 is a diagram showing a configuration of a fourth filter having a virtual ring zone;

FIG. 12 is a view showing the relationship between L / S size and L / S size in the third embodiment.
A characteristic diagram showing a relationship with OF;

FIG. 13 shows oblique L / S size and D in the third embodiment.
A characteristic diagram showing a relationship with OF;

FIG. 14 is a diagram showing a configuration of a fifth filter used in the fourth embodiment;

FIG. 15 shows L / S size and DOF in the fourth embodiment.
Characteristic diagram showing the relationship with

FIG. 16 is a characteristic diagram showing a relationship between a punch pattern size and DOF in the fourth embodiment.

FIG. 17 is a schematic configuration diagram showing a projection exposure apparatus according to a fifth embodiment;

FIG. 18 shows L / S size and DO in the fifth embodiment.
A characteristic diagram showing a relationship with F;

FIG. 19 is a schematic diagram for explaining the operation of the fifth embodiment;

FIG. 20 is a schematic configuration diagram showing a projection exposure apparatus according to a sixth embodiment;

FIG. 21 is a schematic configuration diagram showing a projection exposure apparatus according to a seventh embodiment;

FIG. 22 is a perspective view showing a specific configuration example of a pupil filter that suppresses heat generation.

FIG. 23 is a schematic configuration diagram showing a conventional projection exposure apparatus.

FIG. 24 is a diagram for explaining a problem of the conventional device;

FIG. 25 is a diagram showing an example of a filter used in place of an aperture stop,

FIG. 26 is a characteristic diagram showing a relationship between a pattern size and a depth of focus in a conventional device;

FIG. 27 is a diagram showing a relationship between a fourth filter and the direction of L / S.

FIG. 28 is a diagram showing a relationship between a fourth filter and the direction of L / S.

FIG. 29 is a characteristic diagram illustrating a relationship between a pattern size and a depth of focus when the L / S has a directionality of 45 degrees.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Lamp, 2 ... Elliptical reflecting mirror, 3 ... Second focus of elliptical reflecting mirror 2, 4 ... Input lens, 5 ... Optical integrator, 6
... output lens, 7 ... collimation lens,
8: reticle (mask), 9 ': special aperture,
10: Filter, 11, 12: Cold mirror, 13: Lamp house, 14: Projection optical system, 15: Wafer, 16 ': Filter. 20 ... Fourth filter, 2
1, 51, 61 ... optical axis, 22, 52, 62
… Light transmitting part, 23, 53, 63… light shielding part, 3
0: translucent substrate, 31: translucent film,
34: transparent film, 36: opaque film,
37: phase shifter, 40: phase filter (pupil filter), 50: fourth filter having an annular zone, 60: 5
First filter.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shuichi Tamamushi 1 Kosaka Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture (72) Inventor Keiji Horioka 1 Kokomu-Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Address Toshiba Research Institute, Inc. (56) References JP-A-61-91662 (JP, A) JP-A-3-11345 (JP, A) JP-A-4-76551 (JP, A) JP-A-2- 140743 (JP, A) JP-A-5-67558 (JP, A) JP-A-4-267515 (JP, A) JP-A-3-27516 (JP, A) JP-A-5-181256 (JP, A) JP-A-5-166700 (JP, A) JP-A-5-47628 (JP, A) U.S. Pat. No. 4,890,309 (US, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/027 G03F 7/20

Claims (7)

(57) [Claims] 1. A projection exposure apparatus for projecting and exposing a pattern of a mask onto a wafer via a projection optical system, wherein a light source for illuminating the mask is provided with an intensity distribution in an emission plane of the light source four times with respect to an optical axis. Symmetric and off-axis 4
The intensity is increased in one region, a substrate having a light-transmitting property with respect to exposure light is arranged at a pupil position of the projection optical system, and the thickness or the refractive index of the substrate has a distribution. Projection exposure equipment. 2. A first condensing optical system for condensing light from a light source, a homogenizing optical system for homogenizing light condensed by the first condensing optical system, and a A special stop provided at the light source surface position on the emission side, a second condensing optical system for condensing light obtained through the special stop and irradiating the light to the mask, and projecting light transmitted through the mask onto the wafer A projection optical system for transferring a pattern formed on a mask onto a wafer, wherein the special stop has a center of a substantially figure on a concentric circle centered on an optical axis, and is located within a light source plane. Are relatively four times symmetrical with respect to the optical axis, and the intensity is increased in four regions off the optical axis. A projection exposure apparatus comprising a region whose radial direction is narrow. 3. A projection exposure apparatus for projecting and exposing a pattern of a mask onto a wafer via a projection optical system, wherein a light source for illuminating the mask is provided with an intensity distribution in an emission plane of the light source four times with respect to an optical axis. The intensity is increased in four regions symmetrically off the optical axis, and the intensity of the central portion of the light source is increased. As the mask, a pattern of a translucent film is formed on a translucent substrate. A projection exposure apparatus characterized in that a phase difference of light passing through the light-transmitting substrate with respect to light passing through the light-transmitting substrate satisfies the following range : 180 × (2n + 1) ± 30 (degrees): n is an integer. 4. A projection exposure apparatus for projecting and exposing a pattern of a mask onto a wafer via a projection optical system, wherein a light source for illuminating the mask is provided with an intensity distribution in an emission plane of the light source four times with respect to an optical axis. The intensity is increased in four regions symmetrically off the optical axis, and the intensity of the central part of the light source is increased. As the mask, a pattern is formed by a light-shielding film on a light-transmitting substrate. A light-transmitting film is provided around the pattern or at a portion other than the periphery, and a phase difference between light passing through the light-transmitting film and light passing through the light-transmitting substrate is 180 × (2n + 1) ± 30 (degrees). ): A projection exposure apparatus wherein n satisfies the following range : 5. A projection exposure apparatus for projecting and exposing a pattern of a mask onto a wafer via a projection optical system, wherein a light source for illuminating the mask is provided with an intensity distribution in an emission plane of the light source four times with respect to an optical axis. Symmetric and off-axis 4
And the intensity of the central portion of the secondary light source is increased in at least one region, and a pattern is formed at least in part by a light-transmitting film on the light-transmitting substrate as the mask. A projection exposure apparatus, wherein a phase difference between light passing through a pattern and light passing through a light-transmitting substrate satisfies the following range : 180 × (2n + 1) ± 30 (degrees): n is an integer. . 6. A projection exposure apparatus for projecting and exposing a pattern of a mask onto a wafer through a projection optical system, wherein an intensity distribution of a light source illuminating the mask is interposed between one area or an optical axis deviated from an optical axis. In the two regions symmetrical in intensity, the transmittance distribution of the pupil of the projection optical system, the transmittance along the diameter direction of the pupil including the region where the intensity of the light source is high on the pupil, A projection exposure apparatus, wherein the intensity distribution of the light source and the transmittance distribution of the pupil are synchronously rotated about an optical axis during exposure. 7. A projection exposure apparatus for projecting and exposing a pattern of a mask onto a wafer via a projection optical system, wherein an intensity distribution of a light source for illuminating the mask is four-fold symmetrical with respect to an optical axis and from an optical axis. The intensity is increased in the four deviated areas, and the transmittance distribution of the pupil of the projection optical system is increased in the side direction or the diagonal direction of the rectangle including the four areas in which the intensity of the light source is increased on the pupil. Wherein the intensity distribution of the light source and the transmittance distribution of the pupil are synchronously rotated about an optical axis during exposure.