JP3323815B2 - Exposure method and exposure apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposing method and an exposing apparatus, and more particularly, to exposing a photosensitive substrate with a fine circuit pattern, for example, a semiconductor chip such as an IC or LSI, a display element such as a liquid crystal panel, a magnetic head, and the like. It is suitable for use in the manufacture of various devices such as a detection device and an imaging device such as a CCD.

[0002]

2. Description of the Related Art Conventionally, when devices such as ICs, LSIs, and liquid crystal panels are manufactured using photolithography technology, circuits formed on the surface of a photomask or reticle (hereinafter, referred to as "mask"). A projection exposure method and projection in which a pattern is projected onto a photosensitive substrate such as a silicon wafer or a glass plate (hereinafter, referred to as a “wafer”) coated with a photoresist or the like by a projection optical system, and transferred (exposed) there. An exposure apparatus is used.

In recent years, in response to the higher integration of the above devices, there has been a demand for miniaturization of a pattern to be transferred to a wafer, that is, higher resolution and larger area of one chip on the wafer.

Accordingly, the above-described projection exposure method and projection exposure apparatus, which form the center of microfabrication technology for wafers,
At present, in order to form an image (circuit pattern image) having a dimension (line width) of 0.5 / μm or less over a wide range, improvement in resolution and enlargement of an exposure area are being attempted.

FIG. 37 shows a schematic view of a conventional projection exposure apparatus. In FIG. 37, 191 is an excimer laser as a light source for exposure to far ultraviolet rays, 192 is an illumination optical system, 193 is illumination light emitted from the illumination optical system 192, 194 is a mask, 1
Reference numeral 95 denotes an optical system (projection optical system) 19 which exits from the mask 194.
Reference numeral 196 denotes an object-side exposure light, reference numeral 196 denotes a reduction type projection optical system, reference numeral 197 denotes an image-side exposure light which exits from the projection optical system 196 and enters a substrate 198, reference numeral 198 denotes a wafer which is a photosensitive substrate,
Reference numeral 99 denotes a substrate stage for holding a photosensitive substrate.

[0006] The laser light emitted from the excimer laser 191 is guided to the illumination optical system 192 by the routing optical systems (190a, 190b), and the illumination optical system 192 provides a predetermined light intensity distribution, light distribution, and opening angle (Sekiguchi). The mask 19 is adjusted so as to have the illumination light 193 having several NA) or the like.
Light 4 On the mask 194, a pattern having a size obtained by reciprocally multiplying (for example, 2 times, 4 times, or 5 times) the fine pattern formed on the wafer 198 by a projection magnification of the projection optical system 196 is formed on a quartz substrate by chrome or the like. And illumination light 1
93 is transmitted and diffracted by the fine pattern of the mask 194, and becomes the object side exposure light 195. The projection optical system 196 includes:
The object-side exposure light 195 is converted into image-side exposure light 197 that forms a fine pattern of the mask 194 on the wafer 198 at the above-described projection magnification and with sufficiently small aberration.

The image-side exposure light 197 has a predetermined numerical aperture NA (= Sin
(Θ)) converges on the wafer 198 to form an image of a fine pattern on the wafer 198. The substrate stage 199 includes a plurality of different areas (shot areas: 1) on the wafer 198.
In the case where a fine pattern is sequentially formed on an area which becomes one or a plurality of chips, the projection optical system 196 of the wafer 198 is moved stepwise along the image plane of the projection optical system.
Has changed its position with respect to

Although the above-described projection exposure apparatus using an excimer laser as a light source has a high projection resolution, it is technically difficult to form a pattern image of, for example, 0.15 μm or less.

[0009] The projection optical system 196 has a resolution limit due to a trade-off between the optical resolution due to (exposure) wavelength and the depth of focus. The resolution R of the resolution pattern and the depth of focus DOF by the projection exposure apparatus are expressed by the following Rayleigh formulas (1) and (2).

R = k1 = (λ / NA) ‥‥‥ (1) DOF = k2 = (λ / NA2) ‥‥‥ (2) where λ is the exposure wavelength, and NA is the brightness of the projection optical system 196. Are image-side numerical apertures, k1 and k2, which are constants determined by the development process characteristics of the wafer 198 and the like, and are usually about 0.5 to 0.7. This equation (1) and (2)
From the formula, there is "higher NA" to increase the numerical aperture NA in order to increase the resolution to reduce the resolution R. However, in actual exposure, the DOF of the projection optical system 196 is DOF.
It is difficult to increase the NA higher than a certain value because it is necessary to set the value to a certain value or more. Therefore, in order to increase the resolution, the exposure wavelength λ is eventually reduced to “short wavelength”.
Is required.

However, as the exposure wavelength is shortened, a serious problem arises. It is the projection optical system 196
Is that the glass material of the lens that constitutes is lost. The transmittance of most glass materials is close to 0 in the deep ultraviolet region,
Using a special manufacturing method for exposure equipment (exposure wavelength about 248
nm), fused quartz exists as a glass material.
The transmittance of the fused quartz also sharply decreases for an exposure wavelength of 193 nm or less. It is very difficult to develop a practical glass material in a region having an exposure wavelength of 150 nm or less corresponding to a fine pattern having a line width of 0.15 μm or less. In addition, the glass material used in the deep ultraviolet region must satisfy various conditions such as durability, uniformity of refractive index, optical distortion, workability, etc. in addition to transmittance. Existence is at stake.

As described above, in the conventional projection exposure method and projection exposure apparatus, it is necessary to reduce the exposure wavelength to about 150 nm or less in order to form a pattern having a line width of 0.15 μm or less on a wafer. On the other hand, at present, there is no practical glass material in this wavelength region, so that a pattern having a line width of 0.15 μm or less cannot be formed on the wafer.

US Pat. No. 5,415,835 discloses a technique for forming a fine pattern by two-beam interference exposure. According to the two-beam interference exposure, a pattern having a line width of 0.15 μm or less is formed on a wafer. be able to.

The principle of two-beam interference exposure will be described with reference to FIG. In the two-beam interference exposure, a laser beam L151 having coherence from a laser 151 and being a parallel beam is converted into laser beams L151a and L151 by a half mirror 152.
b, and the two laser beams (coherent parallel light beams) are reflected by the plane mirrors 153a and 153b to make the two laser beams (coherent parallel light beams) greater than 0 and 90, respectively.
The interference fringes are formed at the intersections by intersecting the wafer 154 at a certain angle. By exposing and exposing the wafer 154 with (the light intensity distribution of) the interference fringes, a fine periodic pattern corresponding to the light intensity distribution of the interference fringes is formed on the wafer 154.

The two light beams L151a and L151b are
In the case where the wafer intersects with the perpendiculars formed on the 54 surfaces in a state inclined at the same angle in the opposite directions to each other on the wafer surface, the resolution R in the two-beam interference exposure is expressed by the following equation (3).

R = λ / (4 sin θ) = λ / 4NA = 0.25 (λ / NA) (3) where R is the width of each of L & S (line and space), ie, interference fringes. The width of each of the light and dark portions is shown. Β represents the incident angle (absolute value) of the two light beams with respect to each image plane, and NA = Sin θ.

Comparing equation (1), which is the equation for resolution in normal projection exposure, with equation (3), which is the equation for resolution in two-beam interference exposure, the resolution R of two-beam interference exposure is expressed by equation (1). Since this corresponds to the case where k1 = 0.25, the two-beam interference exposure can obtain a resolution twice or more as high as that of a normal projection exposure where k1 = 0.5 to 0.7.

Although not disclosed in the above US patent, for example, when λ = 0.248 nm (KrF excimer) and NA =
At 0.6, R = 0.10 μm is obtained.

[0019]

In the two-beam interference exposure, basically, only a simple fringe pattern corresponding to the light intensity of the interference fringes (exposure amount distribution) can be obtained. Difficult to form.

The above-mentioned US Pat. No. 5,415,835 discloses that a simple fringe pattern (periodic pattern), that is, a binary exposure distribution is given to a wafer (resist) by two-beam interference exposure, and then the resolution of the exposure apparatus is increased. Obtaining an isolated line (pattern) by performing normal lithography (exposure) using a mask in which an opening having a size within the range is formed and giving another binary exposure distribution to the wafer Has been proposed.

However, US Pat. No. 5,415,583 mentioned above.
The exposure method disclosed in Japanese Patent Application Laid-Open No. 5-205
In each of the two exposure methods, only a normal binary exposure amount distribution is formed, so that it is difficult to obtain a circuit pattern having a more complicated shape.

The above-mentioned US Pat. No. 5,415,835 discloses that two exposure methods, two-beam interference exposure and normal exposure, are combined. An exposure apparatus which achieves such a combination is specifically shown. Not.

According to the present invention, a circuit pattern having a complicated shape is formed by using two exposure methods, ie, a checkerboard pattern exposure and a normal circuit pattern exposure (normal exposure) as the pattern exposure represented by two-beam interference exposure. It is an object of the present invention to provide an exposure method and an exposure apparatus which can be formed on a wafer.

Another object of the present invention is to provide a line width of 0.15 μm.
An exposure method and an exposure apparatus capable of easily obtaining a circuit pattern including the following parts are provided.

It is another object of the present invention to provide an exposure apparatus which can perform two exposure methods, that is, a checkerboard pattern exposure and a normal exposure.

[0026]

According to a first aspect of the present invention, there is provided an exposure method, comprising illuminating a mask with light from an effective light source using an illumination system, and guiding the light from the mask onto a photosensitive substrate to form a predetermined shape. An exposure method for obtaining a pattern, wherein a first exposure step of exposing a photosensitive substrate by illuminating a first mask having a checkerboard pattern, and exposing the photosensitive substrate by illuminating a second mask A second exposure step of performing a normal pattern exposure, wherein the first exposure step and the second exposure step are performed without interposing a development step, and the first exposure step exposes a first region of the photosensitive substrate. Exposing with a light exposure smaller than a threshold value, and exposing a second area of the photosensitive substrate with an exposure light quantity larger than 0 and smaller than the exposure threshold value in the second exposure step, and exposing a third area of the photosensitive substrate with the light exposure threshold value. Big dew By exposing an amount, the first
A part of the region where the region overlaps the second region and the third region
The pattern of the predetermined shape is obtained depending on the region, and the shape of the effective light source in the first exposure step is a quadrupole.

According to a second aspect of the present invention, in the first aspect of the present invention, the second mask has a three-stage, four-stage, or five-stage transmittance. A third aspect of the present invention is characterized in that, in the first or second aspect of the present invention, the photosensitive substrate is provided with three, four, or five exposure levels by the second mask. According to a fourth aspect of the present invention, in the first aspect of the present invention, the normal pattern exposure is a multi-level exposure. According to a fifth aspect of the present invention, in the first aspect of the present invention, two light beams interfere with each other in the first exposure step. According to a sixth aspect of the present invention, in the first aspect of the present invention, in the first exposure step, two-beam interference is simultaneously performed in two directions orthogonal to each other.

According to a seventh aspect of the present invention, there is provided an exposure apparatus for transferring a pattern on a mask onto the photosensitive substrate using the exposure method according to any one of the first to sixth aspects. I have.

[0029] The method of manufacturing a device according to claim 8 is as follows.
An exposure step of transferring a mask pattern onto the photosensitive substrate using the exposure method according to any one of claims 1 to 6, and a developing step of developing the photosensitive substrate after the exposure step. It is characterized by having.

According to a ninth aspect of the present invention, there is provided a device manufacturing method comprising:
An exposure step of transferring a pattern of a mask onto the photosensitive substrate using the exposure apparatus according to claim 7, and a developing step of developing the photosensitive substrate after the exposure step. .

[0031]

[0032]

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view of a main part of a first embodiment of an exposure apparatus according to the present invention. In the present embodiment, two-beam interference is simultaneously performed in one or two sets (four-beam interference) in two directions orthogonal to each other, and a checkered pattern is formed on the photosensitive substrate by one projection exposure. Then, multiple exposure of a checkerboard pattern (fine pattern) and a circuit pattern (normal pattern) such as a gate pattern at this time is performed, and the threshold value of the photosensitive substrate is appropriately set as described later, so that an arbitrary The pattern has been obtained.

FIG. 1 shows a two-beam interference state in only one direction for simplicity. Here, the multiple exposure means that the photosensitive substrate is exposed a plurality of times with different patterns without going through the developing process.

Next, the exposure apparatus of FIG. 1 will be described. FIG. 1 shows an exposure apparatus using a projection optical system conventionally realized by, for example, a total refraction system.
Some have a NA of 0.6 or more for 8 nm. In the figure, 8
Reference numeral 0 denotes an illumination system, which is capable of performing coherent illumination and partially coherent illumination. 81 is a mask, 8
2 denotes an object side exposure light, 83 denotes a projection optical system, 84 denotes an aperture stop, 85 denotes an image side exposure light, 86 denotes a photosensitive substrate, and 87 denotes a position of a light beam on a pupil plane of the projection optical system 83. It is a schematic diagram.

FIG. 3 is a schematic diagram showing a state in which two-beam interference exposure is performed in one direction. Both the object-side exposure light 82 and the image-side exposure light 85 are composed of two parallel light beams.
Actually, similar two-beam interference is performed in a direction orthogonal to the paper surface.

In such a normal projection exposure apparatus, 2
An embodiment for performing light beam interference exposure will be described.
First, an example in which the mask 81 and the illumination method are set as shown in FIGS. 2 and 3 will be described.

FIG. 2A is a sectional view of a main part of the Levenson-type phase shift mask 90. The horizontal and vertical pitches of the chrome light-shielding portion 91 are expressed by equation (a1), and the pitch of the shifter 92 is expressed by equation (a2). ).

P ₀ = MP = 2MR = M (λ / (2NA)) ‥‥‥ (a1) P _0S = 2P ₀ = M (λ / NA) ‥‥‥ (a2) where R is the resolution, M indicates the magnification of the projection optical system 83, λ indicates the wavelength, and NA indicates the image-side NA of the projection optical system 83.

FIG. 4 is a plan view of a principal part of the Levenson-type phase shift mask 90 shown in FIG. FIG. 2 (B)
Is a shifter edge type phase shift mask 94 having no chrome light-shielding portion, and like the Levenson type, is a shifter 92.
The horizontal and vertical pitches _{P0S of the above} are configured by the equation (a2).

Both of the phase shift masks of FIGS. 2A and 2B have the case where the effective light source of the illumination system is illuminated with a vertically incident parallel light beam (coherence factor σ = 0) as shown in FIG. The transmitted light in the 0th-order diffraction direction, that is, in the vertical direction, cancels out because there is a phase π between the adjacent transmitted lights due to the shifter, and the light does not exist. The two luminous fluxes of the ± 1st-order diffracted light that reinforce each other are aligned with the pattern row direction and 45
° and occur symmetrically with respect to the optical axis of the projection optical system.
Further, second-order or higher-order diffracted light does not contribute to imaging due to the limitation of the NA of the projection optical system. FIG. 7 shows the light intensity distribution on the pupil 87 at this time.

In FIG. 7, the light beams 71, 72, 7 on the pupil plane 87 are shown.
Four beams of 3, 74 interfere. Thereby, the photosensitive substrate 86
A checkered light intensity distribution (fine pattern) is formed on the top.

FIG. 8 is an explanatory diagram of an effective light source when obliquely incident illumination is used as an illumination system using the Levenson mask 90. The illumination system is 0 °, 90 °, 180 ° as shown in FIG.
It is a quadrupole illumination in which four effective light sources are located in the directions of ° and 270 °.

FIG. 9 is an explanatory diagram of the light intensity distribution on the pupil plane 87. FIG. 9A shows a state in which no diffraction light is formed in the pupil 87 and no image can be formed without oblique incidence illumination.

FIG. 9B shows an illumination system in which pupils (87a to 87a) are illuminated obliquely (by oblique incident light from four directions).
87d) shows the state where the ± first-order lights are incident on each other.

FIG. 10 is an explanatory diagram showing that the light intensity distribution on the pupil 87 in FIG. 9 is composed of a combination of light intensity distributions on four pupil planes indicated by 87a to 87d. Eyes 87a-87
d denotes a light beam from each light source (indicated by a black dot), which causes two light beam interference.

That is, two-beam interference at 87a, two-beam interference at 87b, two-beam interference at 87c, and two-beam interference at 87d occur simultaneously, and a superimposed image of these is formed on the photosensitive substrate. In this case, if the four-point illumination system of the effective light source has an incoherent relationship with each other by an integrator such as a fly's eye, the intensity is superimposed.

Next, a method using the mask shown in FIG. 3 will be described. 3 is a conventional chrome mask 10
The pitch of the chrome light-shielding portion 102 in the horizontal and vertical directions is given by Expression (a3). This is the same as equation (a1).

P ₀ = MP = 2MR = M (λ / (2NA)) ‥‥‥ (a3) FIG. 5 is a plan view of a main part of the ordinary chrome mask 101 of FIG. In the case of the mask which is not the phase shift method shown in FIG.
The oblique incidence illumination forms a quadrupole where four effective light sources of °, 90 °, 180 °, and 270 ° are located. In this case, the incident light is a parallel light beam having an angle θ ₀ . Where θ
₀ is represented by equation (a4).

Sin θ ₀ = M / NA ‥‥‥ (a4) For such incident light, the light transmitted through the mask 101 is the 0th-order light, which also goes straight to the angle θ ₀ , and the light of the projection optical system. Two luminous fluxes of −1st-order light in an angle −θ ₀ direction symmetrically traveling with respect to the axis pass through a pupil of the projection optical system and contribute to image formation.

FIG. 12 is an explanatory diagram of the light intensity distribution on the pupil 87 at this time. FIG. 12A shows a state where only the zero-order light is incident on the pupil 87 and the pattern image is not formed when the illumination system is vertically incident illumination.

FIG. 12B shows a pupil plane (87) formed by oblique incidence from four directions (oblique incident light from four directions).
0-order light and + 1st-order light (or -1st-order light) at a-87d)
Are superimposed on each other.

FIG. 13 is an explanatory diagram showing that the light intensity distribution on the pupil 87 in FIG. 12B is composed of a combination of light intensity distributions on four pupil planes indicated by 87a to 87d.

The above is an explanation of an example of a mask and an illumination method for performing two-beam interference exposure using an ordinary projection exposure apparatus. By setting as described above, it is possible to use the maximum NA of the projection optical system. Can be.

The present embodiment has a configuration in which a two-beam interference exposure pattern is exposed two-dimensionally to obtain a checkerboard pattern. FIG. 14 is a schematic diagram showing an exposure pattern on the photosensitive substrate when two-dimensional two-beam interference exposure is performed in the present embodiment as an exposure amount map. In the present embodiment, for the exposure pattern finally obtained, the exposure amounts in the two directions of the two-beam interference exposure are set to the same value.

In the exposure pattern shown in FIG. 14, the exposure amount has three levels from 0 to 2 as a result of two two-beam interference exposures. On the other hand, a coarse pattern having a size twice as large as the minimum size of the interference exposure is double-exposed by the normal projection exposure with four stages of light amounts 0 to 3.

The exposure threshold value of the photosensitive substrate is larger than 2 which is the maximum value of the exposure amount of the two-beam interference exposure, and
As shown in FIG. 5, the exposure amount of the normal pattern projection exposure is set to less than the maximum value 3. For example, 2.5. FIG.
FIG. 4 is an explanatory diagram of a pattern obtained by double exposure of light beam interference exposure and normal pattern projection exposure.

FIG. 15 schematically shows a mask M of a normal pattern having four stages of transmittance.

A two-beam interference exposure shown in FIG. 14 and a mask M for providing such four-step (0, 1, 2, 3) exposure amounts
The respective exposure amounts of the exposure pattern as a result of the projection exposure performed in the above are shown in the lower part of FIG. The hatched portion indicates a location equal to or higher than the exposure threshold, and this is the final exposure pattern by multiple exposure.

FIG. 17 is an explanatory diagram showing the exposure pattern of the present embodiment. By changing the exposure amount of the projection exposure for each block shown in FIG. 15, a complicated and fine pattern was formed in a wider area.

The projection exposure with such four-step (0, 1, 2, 3) exposure amounts has the multi-level transmittance shown in FIG. 15, and the phase difference is an integral multiple of 2π. The exposure was performed in one exposure by using the halftone mask M.

When the threshold value is set between 1 and 2, a pattern as shown in FIG. 16 is obtained only by two-beam interference, and four exposure levels are produced as shown in FIG. Therefore, it has four stages of transmittance. 0 of these
% Blocks were shielded from light by chrome. Also, 100%
Is composed of only a transparent quartz substrate.

For example, blocks having a transmittance of 25% and 50%, respectively, are formed by vacuum evaporation of a substance having a refractive index n and an absorption coefficient c satisfying n / c = (mλ) / (-1 nT). It is. Where T is 0.25
0.50, and m is an integer of 1 or 2, respectively. Λ is a wavelength.

By adopting such a configuration, the phase change amount is 2π even at the boundary where the transmittance changes.
In this case, the desired pattern shown in FIG. 17 could be formed by overlapping the exposure pattern with the two-beam interference exposure without being affected by the phase shift effect.

In each of the embodiments described above, the transmission type halftone mask has been described. However, the basic configuration is exactly the same for a reflection type halftone mask.

FIG. 39 uses quadrupole illumination as the illumination system.
The four effective light sources S1 and S3 have the same intensity, and the light source S2
In this case, the intensity of the light source S4 is equal to that of the light source S4, but is weaker than the light sources S1 and S3.

The Levenson mask 90 is used as a mask. FIG. 40A is an explanatory diagram of an effective light source when oblique incidence illumination is used as an illumination system. As shown in FIG. 39, the effective light source is quadrupole illumination in which four effective light sources of 0 °, 90 °, 180 °, and 270 ° are located.

FIG. 40 is an explanatory diagram of the light intensity distribution on the pupil 87. FIG. 40A shows a state where no diffracted light is formed in the pupil 87 and an image cannot be formed.

FIG. 40 (B) shows an illumination system in which a pupil (87a) is obtained by obliquely illuminating (by obliquely incident light from four directions).
To 87d), the states in which ± first order light is incident are shown in an overlapping manner.

FIG. 41 is an explanatory diagram showing that the light intensity distribution on the pupil 87 in FIG. 40 is composed of a combination of light intensity distributions on four pupil planes indicated by 87a to 87d. FIG. 42 is a schematic diagram showing an exposure pattern on a photosensitive substrate as a map of an exposure amount when two-dimensional two-beam interference exposure is performed in the present embodiment. In the present embodiment, the exposure amounts in the two directions of the two-beam interference exposure are set to different values for the finally obtained exposure pattern.

In the exposure pattern shown in FIG. 42, as a result of two two-beam interference exposure, the exposure amount has four stages from 0 to 3. On the other hand, a coarse pattern is usually double-exposed by projection exposure at five exposure levels of 0 to 4.

The exposure threshold value of the photosensitive substrate is larger than 3 which is the maximum value of the exposure amount of the two-beam interference exposure, and FIG.
As shown in FIG. 3, the exposure amount of the normal pattern projection exposure is set to less than the maximum value 4.

FIG. 43 is an explanatory diagram of a pattern obtained by double exposure of two-beam interference exposure and normal pattern projection exposure.

In FIG. 43, a mask M schematically shows a normal pattern mask having five stages of transmittance.

Each exposure amount of the exposure pattern as a result of performing the two-beam interference exposure shown in FIG. 42 and the projection exposure with the mask M that provides such five-stage (0, 1, 2, 3, 4) exposure amounts Is shown below FIG. The hatched portion indicates a location equal to or higher than the exposure threshold, and this is the final exposure pattern by multiple exposure.

FIGS. 44 and 45 show exposure patterns according to the present embodiment.
FIG. The pattern was formed over a wider area by changing the exposure amount of the projection exposure for each block shown in FIG. 43 described above.

The five steps (0, 1, 2, 3, 4)
The projection exposure was performed in one exposure by using the multi-valued halftone mask M shown in FIG.

As shown in FIG. 43, five levels of transmittance are provided to generate five levels of exposure. 0 of these
% Blocks were shielded from light by chrome. Also, 100%
Is composed of only a transparent quartz substrate.

As the transmittance, for example, 25%, 50%, 7
Each of the 5% blocks is formed by vacuum vapor deposition of a substance having a refractive index n and an absorption coefficient c satisfying n / c = (mλ) / (− 1 nT). Where T is 0.25
0.50 and 0.75, and m is an integer of 1, 2, and 3, respectively. Λ is a wavelength. By adopting such a configuration, the phase change amount becomes an integral multiple of 2π even at the boundary portion where the transmittance changes, and the exposure pattern is not changed by the phase shift effect, so that the two-beam interference exposure can be performed. By overlapping, a desired pattern shown in FIG. 43 could be formed. In each of the embodiments described above, the transmission halftone mask has been described. However, the basic configuration is exactly the same for a reflection halftone mask.

Next, a second embodiment of the exposure apparatus using the chromium mask shown in FIG. 3 will be described below with reference to FIG.

FIG. 18 is a schematic view showing an embodiment of the exposure apparatus of the present invention. In the figure, 11 is an exposure light source, 12 is an illumination optical system, 13 is a schematic diagram of an illumination mode, 14 is a chrome mask used in the present invention (FIG. 19), 15 is a replacement mask, 16 is a mask changer, and 17 is a mask. A stage, 18 is a projection optical system, 19 is a pupil filter, 20 is a pupil filter changer, 21 is a wafer, and 22 is a wafer stage.

In this exposure apparatus, when performing two-beam interference, the effective light source of the illumination optical system 12 is set as shown in FIG. 22, and as shown at 13a in FIG. 18, the illumination is coherent illumination (perpendicular to the mask). Is switched to a two-beam interference mask 14 described later using a pupil filter 19a with so-called σ (sigma) illumination using a parallel or substantially parallel light beam incident on the mask. In addition, when performing normal projection exposure, 13 in FIG.
As shown by b, the illumination is appropriately switched to partially coherent illumination or the like, and the pupil filter is also appropriately switched or retracted and not used, and the mask is appropriately switched.

Next, the principle of performing the two-beam interference exposure in the exposure apparatus of FIG. 18 will be described with reference to the schematic diagrams of FIGS. 20 and 21, including the description of the configuration of the pupil filter and the two-beam interference mask.

FIG. 20 shows an exposure apparatus using a projection optical system conventionally realized by, for example, a total refraction system. Currently, there is an exposure apparatus having a NA of 0.6 or more for a wavelength of 248 nm. In the figure, reference numeral 161 denotes a two-beam interference mask, which has, for example, a pattern shown in FIG. 162 is an object side exposure light, 163 is a projection optical system, 164 is an aperture stop, 16
5 is an image side exposure light, 166 is a photosensitive substrate (wafer), 167
FIG. 9 is a schematic diagram showing a position of a light beam on a pupil plane 164.

FIG. 9 is a schematic diagram showing a state in which the two-beam interference exposure is performed. Both the object-side exposure light 162 and the image-side exposure light 165 are composed of two parallel light beams.

In such a normal projection exposure apparatus, 2
In order to perform light beam interference exposure, in the present invention, the two light beam interference mask 161 and the illumination method are set as shown in FIG. This will be described below.

FIG. 21 is a cross-sectional view of a two-beam interference mask having a two-dimensional periodic pattern in which the horizontal and vertical pitches of the chrome light-shielding portion 171 are formed by the formula (b1).

P ₀ = 2MP = 4 MR = M (λ / NA) ‥‥‥ (b1) where R is the resolution, P _O is the pitch of the periodic pattern on the two-beam interference mask 161, and P is the photosensitive substrate 166
The pitch of the upper periodic pattern, M indicates the magnification of the projection optical system 163, λ indicates the wavelength, and NA indicates the image-side NA of the projection optical system.

As shown in FIG. 20, in the present invention, the incident light is substantially coherent illumination using a substantially vertical light beam. Under this illumination, normally, the light transmitted through the two-beam interference mask 161 is a straight-forward zero-order light and a projection optical system 163 around the zero-order light.
Optical axis 163a proceeds symmetrically with respect to the angle - [theta] ₀ direction of -
Three luminous fluxes of primary light and + 1-order light in the direction of the angle + θ ₀ pass through the projection optical system 163 and contribute to image formation. In the present invention, a pupil filter ( An aperture stop 164 removes the zero-order light so as not to contribute to imaging. As the pupil filter 164,
In addition, transmission amplitude or transmission light phase may be controlled.

As the pupil filter 164, a filter A having a light-shielding portion in the central area of the optical axis and a filter B having a cross-shaped region as a light-shielding portion shown in FIG. 46 can be applied.

As shown in FIG. 47, any filter may be used as long as only four effective light sources LS1 to LS4 pass.

FIG. 23A is an explanatory diagram of the light intensity distribution (object spectrum) on the pupil 167. FIG.
This shows a state where five lights are distributed in total including the primary light.

FIG. 23B shows a state in which the zero-order light is cut by a filter (for example, FIG. 46) that cuts the zero-order light.

FIG. 48 shows the fourth embodiment of FIG.
FIG. 7 is a schematic diagram showing an exposure pattern on a photosensitive substrate as a map of an exposure amount when four-beam interference exposure is performed using two effective light sources LS1 to LS4. In the case of four-beam interference, an interference state resulting from the addition of the light amplitudes is handled.

In the present embodiment, the amount of exposure from each light source in the four-beam interference exposure is set to the same value for the finally obtained exposure pattern.

In the exposure pattern shown in FIG. 48, as a result of the four-beam interference exposure, the exposure amount has two levels of 0 and 1. On the other hand, by the normal exposure, a coarse pattern
Double exposure is performed at a step exposure amount.

The exposure threshold value of the photosensitive substrate is larger than 1, which is the maximum value of the exposure amount of the four-beam interference exposure, and
As shown in FIG. 9, the exposure amount of the normal pattern projection exposure is set to less than the maximum value 2. For example, 1.5 is set.

FIG. 49 is an explanatory diagram of a pattern obtained by double exposure of four-beam interference exposure and normal pattern projection exposure.

In FIG. 49, a mask M schematically shows a normal pattern mask having three stages of transmittance.

The respective exposure amounts of the exposure pattern as a result of performing the four-beam interference exposure shown in FIG. 48 and the projection exposure with the mask M giving such three-stage (0, 1, 2) exposure amounts are shown in FIG. Shown below. The hatched portion indicates a location equal to or higher than the exposure threshold, and this is the final exposure pattern by multiple exposure.

FIG. 50 is an explanatory diagram showing an exposure pattern of this embodiment. The pattern was formed in a wider area by changing the exposure amount of the projection exposure for each block shown in FIG. 49 described above.

The projection exposure with such three-step (0, 1, 2) exposure amounts was performed in one exposure using the multi-valued halftone mask M shown in FIG.

As shown in FIG. 49, three levels of transmittance are provided to generate three levels of exposure. Among them, the value of the transmittance is arbitrary, for example, 0.50 and 100%. Of these, 0% of the blocks were shielded from light by chrome. Further, 100% of the blocks are constituted only by a transparent quartz substrate.

For example, a block having a transmittance of 50% is formed by vacuum-depositing a substance having a refractive index n and an absorption coefficient c satisfying n / c = (mλ) / (-1 nT). Here, T is 0.50, and m is an integer of 1 each. Λ is a wavelength.

By adopting such a configuration, the phase change amount is 2π even at the boundary where the transmittance changes.
.Times..times..times..times..times..times..times..times..times..times.

In each of the above embodiments, the transmission type halftone mask has been described. However, the basic configuration is exactly the same even for a reflection type halftone mask.

In this manner, the two-beam interference exposure is performed by using the same projection exposure apparatus as that for the normal projection exposure. Further, according to this method, since the ± 1st-order light is used, the pitch of the two-beam interference mask can be configured to be twice the normal pitch in terms of exposure magnification. Since there is no need to attach a fine phase film, it is advantageous in mask making and the like.

The above is an explanation of an example of a two-beam interference mask 161 for performing two-beam interference exposure using a normal projection exposure apparatus and an illumination method. If each element is set as described above, the projection optical system Can be used.

FIG. 24A is a schematic view of a mask 161, and FIG. 24B is a diagram showing a pupil filter 19a according to the present embodiment, in which zero-order light is cut to cause two-beam interference in two directions, a horizontal direction and a vertical direction. And a checkerboard pattern image obtained on the surface of the photosensitive substrate 21.

FIG. 17 shows a state in which a circular pattern image is formed two-dimensionally and periodically. However, below the limit resolution, there is no spatial high-frequency component, and the threshold level of the resist is similar. This indicates that a checkerboard-shaped rectangular portion can be rounded to form a distribution in a fine matrix shape having a circular shape.

In the present invention, only the exposure of a checkerboard pattern with high resolution by two-beam interference exposure is performed by setting the threshold value of the photosensitive substrate to project a seemingly disappearing pattern by projection exposure of a normal circuit pattern and multiple exposure. It is an object of the present invention to obtain a circuit pattern of an arbitrary shape by selectively restoring by a fusion effect of both pattern exposures.

Next, the principle of pattern formation by multiple exposure will be described. In the present invention, an arbitrary-shaped pattern is obtained by double exposure of a checkerboard pattern exposure and a circuit pattern, but in the following double exposure, a periodic pattern is used instead of a checkerboard pattern for simplicity. A case in which a pattern of an arbitrary shape is obtained by double exposure of this and a circuit pattern will be described.

FIGS. 25 to 33 are explanatory views of the exposure method according to the present invention. FIG. 25 is a flowchart showing the exposure method according to the present invention. FIG. 25 shows each block of the periodic pattern exposure step, the projection exposure step (normal pattern exposure step), and the development step, which constitute the exposure method of the present invention, and the flow thereof. In the figure, the order of the periodic pattern exposure step and the projection exposure step may be reversed, and when one of the steps includes a plurality of exposure steps, each step may be performed alternately.

In addition, between each exposure step. Although there is a step of performing precise alignment, the illustration is omitted here.

An exposure method and an exposure apparatus according to the present invention are characterized in that double exposure of periodic pattern exposure and normal pattern exposure is performed on a substrate to be exposed (photosensitive substrate).

Here, the normal pattern exposure is exposure in which the resolution is lower than that of the periodic pattern exposure, but the exposure can be performed with an arbitrary pattern, such as projection exposure in which a mask pattern is projected by a projection optical system.

The pattern (normal pattern) exposed by the normal pattern exposure includes a fine pattern having a resolution equal to or less than the resolution, and the periodic pattern exposure forms a periodic pattern having substantially the same line width as the fine pattern. A large pattern having a resolution equal to or larger than the resolution of the normal pattern exposure is not limited to the line width of the periodic pattern exposure, but an integer multiple is effective.

Normally, the pattern exposure has an arbitrary shape and may be oriented in various directions. Generally, an IC pattern has two directions, one direction and the direction perpendicular to the other.
In many cases, it is oriented in a direction, and the finest pattern is often limited to only one specific direction.

When performing periodic pattern exposure by double exposure, it is important to make the direction of the periodic pattern coincide with the direction of the finest pattern of the normal pattern.

The exposure is performed so that the center of the peak of the periodic pattern coincides with the center of a fine pattern having a resolution lower than that of the normal pattern.

The double exposure in the present invention means a double exposure of a periodic pattern exposure and a normal pattern exposure. The periodic pattern exposure is repeated several times in parallel with the direction of the finest pattern of the normal pattern exposure. Exposure.

Each of the periodic pattern exposure and the normal pattern exposure of the exposure method and the exposure apparatus according to the present invention comprises one or a plurality of exposure steps. Different exposure dose distributions are given to the photosensitive substrate.

When performing exposure according to the flow of FIG. 25, first, a wafer (photosensitive substrate) is
Exposure is performed in a periodic pattern as shown in FIG. The numbers in FIG. 26 represent the exposure amount, and the hatched portions in FIG. 26A indicate the exposure amount 1 (actually arbitrary) and the white portions indicate the exposure amount 0.

When developing only such a periodic pattern after exposure, usually, the exposure threshold value E of the resist on the photosensitive substrate is used.
th is the exposure amount 0 as shown in the lower graph of FIG.
Set between 1 and 1. The upper part of FIG. 26B shows a lithography pattern (concavo-convex pattern) finally obtained.

FIG. 27 shows the dependence of the film thickness after development on the amount of exposure and the exposure threshold value of the resist on the photosensitive substrate in this case, with the positive resist (hereinafter referred to as "positive") and the negative resist. Each of the resists (hereinafter referred to as “negative type”) is shown. In the case of the positive type, when the exposure threshold value Eth or more, and in the case of the negative type, the exposure threshold value Eth or less,
The film thickness after development becomes zero.

FIG. 28 is a schematic diagram showing a state in which a lithography pattern is formed through the development and etching processes when such exposure is performed, for a negative type and a positive type.

In this embodiment, unlike the normal exposure sensitivity setting, as shown in FIG. 29 (same as FIG. 26A) and FIG. 30, when the central exposure amount in the periodic pattern exposure is set to one. , Exposure threshold Et of the resist on the exposed substrate
h is set to be larger than 1.

When the exposure pattern (exposure amount distribution) shown in FIG. 26 where only the base pattern exposure is performed is developed, the exposure amount is insufficient. Does not occur, and no lithography pattern is formed by etching.
This can be regarded as the disappearance of the periodic pattern (note that the present invention will be described using an example using a negative type, but the present invention can also be applied to a positive type). .

In FIG. 30, the upper part shows the lithography pattern (nothing can be done), and the lower part shows the relationship between the exposure distribution and the exposure threshold. In addition, E1 described below shows an exposure amount in periodic pattern exposure, and E2 shows an exposure amount in normal projection exposure.

The feature of the present embodiment is that a high-resolution exposure pattern, which is apparently lost only by periodic pattern exposure, is fused with an exposure pattern of any shape including a pattern having a size equal to or smaller than the resolution of an exposure apparatus by ordinary projection exposure. And selectively exposing only the desired area to the exposure threshold or more of the resist,
Finally, a desired lithography pattern can be formed.

FIG. 7A shows an exposure pattern obtained by normal projection exposure (normal pattern exposure). Since the pattern is a fine pattern, it cannot be resolved and the intensity distribution on the object to be exposed is blurred and wide. . In the present embodiment, a fine pattern having a paper width of about half the resolution of normal projection exposure is used.

Assuming that the projection exposure for forming the exposure pattern of FIG. 31A is performed on the same region of the same resist without the development step after the periodic pattern exposure of FIG. 29,
FIG. 31B shows the total exposure distribution on the resist surface.
It looks like the graph below. Here, the ratio of the exposure amount E1 of the periodic pattern exposure to the exposure amount E2 of the projection exposure is 1: 1, and the exposure threshold value Eth of the resist is equal to the exposure amount E1.
(= 1) and the sum (= 2) of the exposure amount E1 and the exposure amount E2 of the projection exposure, the lithography pattern shown in the upper part of FIG. 31B is formed.

At this time, the center of the normal pattern is matched with the peak of the periodic pattern. Also, the direction of the normal pattern and the direction of the periodic pattern are matched.

The isolated line pattern shown in the upper part of FIG. 31 (B) has a resolution of periodic pattern exposure and has no simple periodic pattern. Therefore, a high-resolution pattern higher than the resolution that can be realized by ordinary projection exposure is obtained.

Here, suppose that the projection exposure for forming the exposure pattern shown in FIG. 32 (the line width twice as large as that of the exposure pattern shown in FIG. 29 and the exposure threshold or more (here, the exposure amount twice as large as the threshold)). ) Is superimposed on the same region of the same resist without the development step after the periodic pattern exposure of FIG. At this time, the symmetry of the superposed pattern is good by making the center of the normal pattern coincide with the peak position of the periodic pattern exposure,
A good pattern image is obtained.

The total exposure distribution of this resist is shown in FIG.
As shown in (B), the exposure pattern of the two-beam interference exposure (periodic pattern exposure) disappears, and finally only the lithography pattern by the projection exposure is formed.

As shown in FIG. 33, the principle is the same when the exposure is performed with a line width three times the exposure pattern of FIG.
With an exposure pattern having a line width of four times or more, the line width of a finally obtained lithography pattern is obvious from a combination of an exposure pattern having a double line width and an exposure pattern having a triple line width. All the lithography patterns that can be realized by projection exposure can also be formed in the present embodiment.

By adjusting the exposure amount distribution (absolute value and distribution) and the resist threshold value of the photosensitive substrate by each of the periodic pattern exposure and the projection exposure briefly described above,
FIGS. 30, 31 (B), 32 (B), and 33
The minimum line width is composed of a combination of various types of patterns as shown in FIG.
A circuit pattern serving as the pattern (B) can be formed.

The principles of the above-described exposure methods can be summarized as follows: (a-1) A pattern area that is not subjected to projection exposure (normal pattern exposure), that is, a periodic exposure pattern equal to or less than the exposure threshold of a resist, disappears by development.

(A-2) Regarding the pattern area of the projection exposure performed with the exposure amount equal to or less than the exposure threshold value of the resist, the exposure pattern having the resolution of the periodic pattern exposure determined by the combination of the projection exposure and the periodic pattern exposure is used. It is formed.

(A-3) In the pattern area of the projection exposure performed with the exposure amount equal to or more than the exposure threshold value, a fine pattern (corresponding to a mask) which is not resolved by the projection exposure alone is similarly formed.

That is to say. Further, as an advantage of the exposure method, if the periodic pattern exposure having the highest resolution is performed by two-beam interference exposure, a much larger depth of focus can be obtained as compared with normal exposure.

In the above description, the order of the periodic pattern exposure and the projection exposure is the order of the periodic pattern exposure, but is not limited to this order.

FIG. 34 is an explanatory diagram of one embodiment of a specific optical system in the exposure apparatus of the present invention.

This embodiment shows a case where the present invention is applied to a step-and-repeat or step-and-scan exposure apparatus for lithography of submicron or quarter micron or less.

In the figure, a laser beam from a laser light source 201 is enlarged in beam diameter by a beam shaping unit 205 and is incident on an incident surface 206 a of an optical integrator 206. The optical integrator 206 is configured by two-dimensionally arranging a plurality of minute lenses (fly-eye lenses) 6-i (i = 1 to N) having a quadrangular or cylindrical cross section at a predetermined pitch. A secondary light source image is formed near the exit surface 206b.

A stop 207 determines the shape of the secondary light source. The diaphragm 207 is operated by a diaphragm exchange mechanism (actuator) 216 in accordance with the illumination conditions.
a and 207b can be switched so as to be located in the optical path. As the stop 207, for example, an ordinary circular aperture stop, an annular illumination stop for changing the light intensity distribution on the pupil plane 214 of the projection lens 213, a quadrupole illumination stop, a small σ value illumination stop, etc. And one of them is selected and arranged in the optical path.

In the present embodiment, by using various apertures 207, the light flux incident on the condenser lens 208 is changed variously, and the light intensity distribution on the pupil plane 214 of the projection optical system 213 is appropriately controlled. The condensing lens 208 includes a plurality of lenses 2 near the exit surface 206 b of the optical integrator 206.
A plurality of light beams emitted from the next light source and transmitted through the stop 207 are condensed, reflected by the mirror 209 and superposed on the surface of the masking blade 210 as a surface to be irradiated, and the surface is uniformly irradiated. The masking blade 210 is composed of a plurality of movable light shielding plates so that an arbitrary opening shape is formed.

Reference numeral 211 denotes an image forming lens which transfers the shape of the opening of the masking blade 210 onto a reticle (mask) 212 as a surface to be irradiated, and uniformly illuminates a required area on the reticle 212.

Reference numeral 213 denotes a projection optical system (projection lens) for reducing and projecting a circuit pattern on the reticle 212 onto a wafer (substrate) 215 placed on a wafer chuck. Reference numeral 214 denotes a pupil plane of the projection optical system 213. On the pupil plane 214, various aperture stops shown in FIG.

In the optical system according to the present embodiment, the masking blade 210, the reticle 212, and the wafer 215 have a conjugate relationship with each other. Also, the stop 207a and the pupil plane 214 of the projection optical system 213 have a substantially conjugate relationship.

In this embodiment, with the above configuration,
The pattern on the reticle 212 surface is subjected to reduced projection exposure on the wafer 215 surface. The device (semiconductor element) is manufactured through a predetermined development process.

In the present embodiment, as described above, apertures having different aperture shapes are selected and used on the pupil plane 214 of the projection optical system 213 according to the pattern shape on the target reticle 212 surface. The light intensity distribution is varied.

In the present invention, (a) as the illumination method of the illumination optical system, it is applicable to illuminate the mask pattern with light from a KrF excimer laser, an ArF excimer laser or an F2 excimer laser.

(B) In an exposure apparatus, a refracting system and a reflecting system
It is applicable to project the mask pattern by a projection optical system composed of either a refraction system or a reflection system.

(C) As the exposure apparatus, a step-and-repeat method or a step-and-scan method can be applied.

Next, an embodiment of a method for manufacturing a semiconductor device using the above-described projection exposure apparatus will be described.

FIG. 35 shows a flow of manufacturing a semiconductor device (a semiconductor chip such as an IC or an LSI, or a liquid crystal panel or a CCD).

In step 1 (circuit design), a circuit of a semiconductor device is designed. Step 2 is a process for making a mask on the basis of the circuit pattern design.

On the other hand, in step 3 (wafer manufacturing), a wafer is manufactured using a material such as silicon. Step 4
The (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by lithography using the prepared mask and wafer.

The next step 5 (assembly) is called a post-process, and is a process of forming a semiconductor chip using the wafer prepared in step 4, and includes an assembly process (dicing and bonding) and a packaging process (chip encapsulation). And the like.

In step 6 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device manufactured in step 5 are performed. Through these steps, a semiconductor device is completed and shipped (step 7).

FIG. 36 shows a detailed flow of the wafer process. Step 11 (oxidation) oxidizes the wafer's surface. Step 12 (CVD) forms an insulating film on the wafer surface.

In step 13 (electrode formation), electrodes are formed on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted into the wafer. Step 15
In (resist processing), a photosensitive agent is applied to the wafer. Step 16 (exposure) uses the above-described exposure apparatus to print and expose the circuit pattern of the mask onto the wafer.

In step 17 (development), the exposed wafer is developed. In step 18 (etching), portions other than the developed resist are removed. In step 19 (resist stripping), the resist that has become unnecessary after the etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer.

By using the manufacturing method of the present embodiment, it is possible to easily manufacture a highly integrated semiconductor device which has conventionally been difficult to manufacture.

[0167]

As described above, according to the present invention, (a-1) the use of two exposure methods, pattern exposure represented by two-beam interference exposure and normal pattern exposure (normal exposure), An exposure method and an exposure apparatus capable of forming a circuit pattern on a wafer.

(A-2) An exposure method and an exposure apparatus capable of easily obtaining a circuit pattern having a portion having a line width of 0.15 μm or less.

(A-3) An exposure apparatus capable of performing two exposure methods, pattern exposure and normal exposure. Can be achieved.

In particular, according to the present invention, (a-4) a complex pattern having a fine line width of, for example, 0.15 μm or less can be obtained by fusing two-beam interference exposure with ordinary exposure.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of an exposure apparatus for two-beam interference of the present invention.

FIG. 2 shows a mask and an illumination method used in the apparatus of FIG.
Explanatory diagram showing an example

FIG. 3 shows a mask and an illumination method used in the apparatus shown in FIG.
Explanatory diagram showing an example

FIG. 4 is an explanatory view of a mask according to the present invention.

FIG. 5 is an explanatory view of a mask according to the present invention.

FIG. 6 is an explanatory diagram of an effective light source of the illumination optical system in FIG. 1;

FIG. 7 is an explanatory diagram of a light intensity distribution on a pupil plane in FIG. 1;

FIG. 8 is an explanatory diagram of an effective light source of the illumination optical system of FIG. 1;

FIG. 9 is an explanatory diagram of a light intensity distribution on a pupil plane in FIG. 1;

FIG. 10 is an explanatory diagram of a light intensity distribution on a pupil plane in FIG. 1;

11 is an explanatory diagram of an effective light source of the illumination optical system in FIG.

FIG. 12 is an explanatory diagram of a light intensity distribution on a pupil plane in FIG. 1;

FIG. 13 is an explanatory diagram of a light intensity distribution on a pupil plane in FIG. 1;

FIG. 14 is an explanatory diagram of a two-beam interference pattern according to the present invention.

FIG. 15 is an explanatory diagram of a two-beam interference pattern and a normal pattern according to the present invention.

FIG. 16 is an explanatory diagram of a checkered pattern according to the present invention.

FIG. 17 is an explanatory diagram of an arbitrary pattern according to the present invention.

FIG. 18 is a schematic view of a main part of the exposure apparatus of the present invention.

FIG. 19 is an explanatory diagram of a mask used in FIG. 18;

FIG. 20 is a diagram illustrating the principle of two-beam interference according to the present invention.

FIG. 21 is an explanatory diagram of a two-beam interference mask and an illumination method according to the present invention.

FIG. 22 is an explanatory diagram of the effective light source in FIG. 20;

FIG. 23 is an explanatory diagram of a light intensity distribution on a pupil plane in FIG. 20;

FIG. 24 is an explanatory diagram of the mask and the checkerboard pattern image of FIG. 20;

FIG. 25 is a flowchart of the exposure method of the present invention.

FIG. 26 is an explanatory view showing an exposure pattern by two-beam interference exposure.

FIG. 27 is an explanatory diagram showing exposure sensitivity characteristics of a resist.

FIG. 28 is an explanatory view showing pattern formation by development.

FIG. 29 is an explanatory view showing an exposure pattern by ordinary two-beam interference exposure

FIG. 30 is an explanatory view showing an exposure pattern by two-beam interference exposure in the present invention.

FIG. 31 is an explanatory view showing an example of an exposure pattern (lithography pattern) that can be formed in the embodiment of the present invention.

FIG. 32 is an explanatory view showing another example of the exposure pattern (lithography pattern) that can be formed in the embodiment of the present invention.

FIG. 33 is an explanatory view showing an example of an exposure pattern (lithography pattern) that can be formed in the first embodiment of the present invention.

FIG. 34 is a schematic view of a main part of an exposure apparatus according to the present invention.

FIG. 35 is a flowchart of a device manufacturing method according to the present invention.

FIG. 36 is a flowchart of a device manufacturing method of the present invention.

FIG. 37 is an explanatory view showing a conventional projection exposure apparatus.

FIG. 38 is a schematic view showing an example of a conventional two-beam interference exposure apparatus.

FIG. 39 is an explanatory diagram of an effective light source of the illumination system according to the present invention.

FIG. 40 is an explanatory diagram of a light intensity distribution at a pupil of the exposure apparatus according to the present invention.

FIG. 41 is an explanatory diagram of a light intensity distribution at a pupil of the exposure apparatus according to the present invention.

FIG. 42 is an explanatory diagram of a light pattern on a photosensitive substrate according to the present invention.

FIG. 43 is an explanatory diagram of multiple exposure of two-beam interference and normal exposure according to the present invention.

FIG. 44 is an explanatory diagram of a circuit pattern obtained in the present invention.

FIG. 45 is an explanatory diagram of a circuit pattern obtained in the present invention.

FIG. 46 is an explanatory diagram of a pupil filter according to the present invention.

FIG. 47 is an explanatory diagram of a light intensity distribution on a pupil plane according to the present invention.

FIG. 48 is an explanatory diagram of a light pattern on a photosensitive substrate in four-beam interference according to the present invention.

FIG. 49 is an explanatory diagram of multiple exposure of four-beam interference and normal exposure according to the present invention.

FIG. 50 is an explanatory diagram of a pattern obtained by four-beam interference and normal exposure according to the present invention.

[Explanation of symbols]

 221 Excimer laser 222 Illumination optical system 223 Mask (reticle) 224 Mask (reticle) stage 225 2 Light flux interference mask and mask for normal projection exposure 226 Mask (reticle) changer 227 Projection optical system 228 Wafer 229 XYZ stage 80 Illumination optical system Reference Signs List 81 mask 83 projection optical system 84 aperture stop 86 photosensitive substrate 87 pupil plane 90 Levenson-type mask 94, 101 mask

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akiyoshi Suzuki 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (56) References JP-A-7-226362 (JP, A) (58) Survey Field (Int.Cl. ⁷ , DB name) H01L 21/027 G03F 7/20 521

Claims (9)

(57) [Claims] 1. A mask using light from an effective light source using an illumination system.
To illuminate the light, guide the light from the mask onto the photosensitive substrate, and
An exposure method for obtaining a shape pattern, comprising illuminating a first mask having a checkerboard pattern.
A first exposure step of exposing the photosensitive substrate by means of: exposing the photosensitive substrate by illuminating a second mask
A second exposure step of performing a normal pattern exposure, wherein the first exposure step and the second exposure step sandwich a development step.
It is performed without, the first region of the photosensitive substrate in the first exposure step exposing threshold
And exposing the second region of the photosensitive substrate to 0 in the second exposure step.
Exposure with an exposure amount that is significantly smaller than the exposure threshold
Exposing a third area of the photosensitive substrate to a value greater than the exposure threshold
By exposing the first region and the second region, a portion of the region where the first region and the second region
Obtaining the pattern of the predetermined shape by the third region
And the shape of the effective light source in the first exposure step is quadrupole.
An exposure method, characterized in that: 2. The method according to claim 1, wherein the second mask has three or four steps,
2. The light transmission device according to claim 1, wherein the light transmission device has five transmittances.
Exposure method. 3. The photosensitive substrate according to claim 2, wherein
It is particularly important to provide three, four or five exposure levels.
The exposure method according to claim 1 or 2, wherein 4. The exposure method according to claim 1, wherein said normal pattern exposure is a multi-value exposure. 5. The method according to claim 1, wherein in the first exposure step, two-beam interference
The method according to any one of claims 1 to 4, wherein
Exposure method according to the above. 6. In the first exposure step, two-beam interference is prevented.
The contract is performed simultaneously in two directions orthogonal to each other.
An exposure method according to any one of claims 1 to 5. 7. The dew drop according to any one of claims 1 to 6,
Using a light method, the pattern on the mask on the photosensitive substrate
An exposure apparatus for transferring an image. 8. The dew according to any one of claims 1 to 6,
Using a light method, a mask pattern is formed on the photosensitive substrate.
An exposing step of transferring, and a developing step of developing the photosensitive substrate after the exposing step
And a method for manufacturing a device. 9. An exposure apparatus according to claim 7, wherein
An exposure step of transferring a pattern of the pattern onto the photosensitive substrate, and a developing step of developing the photosensitive substrate after the exposure step
And a method for manufacturing a device.