JP2001244190A - Mask for multiple exposure, exposure method by use thereof, aligner, and method of manufacturing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mask, which is capable of making the optimal exposures of patterns coincide with each other, a line width change in the patterns uniform to exposure, and a range of exposure common to the patterns wide, an exposure method by the use of the same, an aligner, and a method of manufacturing device. SOLUTION: A first pattern comprising cyclic patterns and a second pattern comprising fine line groups which are equal to each other in line width but different from each other in line pitch are subjected to an-exposure operation using a first pattern mask in a multi-exposure process, wherein the first pattern forms a mask, having cyclic patterns that are equal to each other in the ratio of a line width to a line pitch and overlap each other with one of the above fine line groups.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mask for performing multiple exposure, an exposure method using the mask, an exposure apparatus, and a device manufacturing method, and more particularly to performing multiple exposure for exposing a fine circuit pattern onto a photosensitive substrate. The mask is, for example, a semiconductor chip such as an IC / LSI, a display element such as a liquid crystal panel, a detection element such as a magnetic head, various devices such as an imaging element such as a CCD, and a wide area used in micromechanics. Used in the manufacture of patterns.

[0002]

2. Description of the Related Art Conventionally, when devices such as ICs, LSIs, and liquid crystal panels are manufactured by photolithography, a circuit pattern of a photomask or a reticle (hereinafter, referred to as a "mask") is projected onto a projection optical system. A projection exposure method and a projection exposure apparatus are used for projecting onto a photosensitive substrate such as a silicon wafer or a glass plate or the like (hereinafter, referred to as a “wafer”) coated with a photoresist or the like and transferring (exposing) the same onto the photosensitive substrate. ing.

In response to the high integration of the above devices, there is a demand for miniaturization of a pattern to be transferred to a wafer, that is, high resolution, and an increase in the area of one chip on the wafer. In the projection exposure method and the projection exposure apparatus,
In order to form an image having the following dimensions (line width) over a wide range, resolution and exposure area are improved.

FIG. 20 shows a schematic view of a conventional projection exposure apparatus. In FIG. 20, reference numeral 191 denotes an excimer laser as a light source for exposure to far ultraviolet rays, 192 denotes an illumination optical system, 193 denotes illumination light,
Reference numeral 94 denotes a mask, and 195 denotes an optical system 1 coming out of the mask 194.
An object-side exposure light 196 is incident on a reduction projection optical system, 196 is an image-side exposure light exiting from an optical system 196 and incident on a substrate 198, 198 is a wafer as a photosensitive substrate, 199
Denotes a substrate stage for holding a photosensitive substrate.

The laser light emitted from the excimer laser 191 is guided to the illumination optical system 192 by the routing optical system, guided to the illumination optical system 192, and
2, the mask 194 is illuminated by adjusting the illumination light 193 to have a predetermined light intensity distribution, a light distribution, an opening angle (numerical aperture NA), and the like. The mask 194 has a wafer 198
A pattern having a size obtained by multiplying the fine pattern formed thereon by an inverse multiple (for example, 2 times, 4 times, or 5 times) of the projection magnification of the projection optical system 196 is formed on a quartz substrate by chrome or the like.
The illumination light 193 is transmitted and diffracted by the fine pattern of the mask 194, and becomes the object side exposure light 195. Projection optical system 1
Reference numeral 96 denotes an object-side exposure light 195 which reflects the fine pattern of the mask 194 on the wafer 1 at the above-mentioned projection magnification and with a sufficiently small aberration.
The light is converted into image-side exposure light 197 that forms an image on the image 98. As shown in the enlarged view at the bottom of FIG.
The light converges on the wafer 198 at a predetermined numerical aperture NA (= sin θ), and forms an image of a fine pattern on the wafer 198. The substrate stage 199 moves stepwise along the image plane of the projection optical system when sequentially forming a fine pattern in a plurality of different areas (shot areas: areas forming one or more chips) of the wafer 198. Wafer 1
The position of the projection optical system 98 with respect to the projection optical system 196 is changed.

However, it is difficult for a projection exposure apparatus using the above-described excimer laser as a light source to form a pattern of 0.15 μm or less. Projection optical system 1
96 has a resolution limit due to a trade-off between optical resolution and depth of focus due to the exposure wavelength used. The resolution R of the resolution pattern and the depth of focus DOF by the projection exposure apparatus are represented by the following Rayleigh formulas (1) and (2). R = K ₁ (λ / NA) (1) DOF = K ₂ (λ / NA ² ) (2) where λ is the exposure wavelength, and NA is the brightness of the projection optical system 196. , And K ₁ and K ₂ are constants determined by the development process characteristics of the wafer 198 and the like.
The value is about 0.7. From the equations (1) and (2), it is apparent from the equations (1) and (2) that the numerical aperture N
Although there is a “high NA” that increases A, in actual exposure, the depth of focus DOF of the projection optical system 196 needs to be a certain value or more, so that it is impossible to increase the NA higher than a certain value. It can be seen that, in order to increase the resolution, it is necessary to “short-wavelength” the exposure wavelength λ to be eventually reduced.

[0007] However, as the wavelength is shortened, a serious problem occurs. This problem is that the glass material of the lens of the projection optical system 196 runs out. The transmittance of most glass materials is close to 0 in the deep ultraviolet region, and fused quartz and fluorite are present as glass materials manufactured for exposure equipment (exposure wavelength: about 248 nm) using a special manufacturing method. Also sharply decreases at an exposure wavelength of 193 nm or less, and it is very difficult to develop a practical glass material in an exposure wavelength of 150 nm or less. In addition, the glass material used in the deep ultraviolet region must satisfy a plurality of conditions such as durability, uniformity of refractive index, optical distortion, workability, etc., in addition to transmittance. Existence is at stake.

On the other hand, for the substrate to be exposed (photosensitive substrate),
By using an exposure method and an exposure apparatus that performs double exposure of periodic pattern exposure and normal exposure, it is possible to create a circuit pattern having a portion of 0.15 μm or less without shortening the exposure wavelength.

Here, the principle of the double exposure will be described first. In the double exposure, the normal exposure and the periodic pattern exposure are performed without a developing step. In this method, a periodic pattern is exposed below the exposure threshold value of a resist, and thereafter, normal exposure is performed in which the exposure amount has a multi-value distribution. The exposure amount of the normal exposure has a different exposure amount distribution for each small area of the exposure pattern area (exposure area), and each exposure amount is equal to or more than the exposure threshold value. Good. All the exposure amounts mentioned here indicate the exposure amounts on the resist.

FIG. 19 (2) or (3) shows a circuit pattern (lithography pattern) obtained by exposure.
A description will be given by taking the so-called gate pattern shown in FIG. FIG.
Has a minimum line width of 0.1 μm in the horizontal direction, while the line width in the vertical direction is 0.2 μm or more, which is within the range of the resolving power by the normal exposure of the apparatus. According to the double exposure method, for such a two-dimensional pattern having a minimum line width pattern requiring high resolution only in the one-dimensional direction only in the horizontal direction, periodic pattern exposure by, for example, two-beam interference exposure is performed. Perform only in the one-dimensional direction that requires high resolution.

FIG. 18 shows an exposure amount distribution at each exposure stage. Numerical values shown in FIG. 18 represent exposure amounts of the resist. In FIG. 18, FIG.
8 (1) is an exposure amount distribution based on a periodic exposure pattern in which a repeat pattern occurs only in one-dimensional direction. The exposure amount other than the pattern is zero, and the pattern part is 1. FIG. 18B shows an exposure amount distribution by multi-valued normal exposure. The exposure amount other than the pattern is zero, and the pattern portion has a distribution of 1 and 2, here a binary value.
When these exposures are performed by double exposure without going through the development process, a distribution of the sum of the respective exposure amounts is generated on the resist, and the exposure amount distribution is as shown in FIG. here,
When the exposure threshold of the resist is between 1 and 2, 1
A larger portion is exposed, and a pattern shown by a thick line in FIG. 18 (3) is formed by development.

That is, the exposure pattern by the periodic pattern exposure, which is outside the area surrounded by the thick line, is equal to or less than the exposure threshold value of the resist and disappears by development. With respect to the portion where the exposure amount equal to or less than the exposure threshold value of the resist is distributed in the normal exposure, the portion where the sum of the respective exposure patterns of the normal exposure and the periodic pattern exposure is equal to or greater than the exposure threshold value of the resist is formed by development. You. Accordingly, an exposure pattern having the same resolution as the exposure pattern of the periodic pattern exposure, which overlaps the respective exposure patterns of the normal exposure and the periodic pattern exposure, is formed. In the exposure pattern area where the exposure amount equal to or more than the exposure threshold value of the resist is distributed in the normal exposure, an exposure pattern having the same resolution as the exposure pattern of the normal exposure is formed, which overlaps the exposure patterns of the normal exposure and the periodic pattern exposure. Is done.

FIG. 19 shows a pattern and a mask for forming the exposure distribution shown in FIG. FIG.
Reference numeral 9 (1) denotes a pattern and a mask in which a repetitive pattern is generated only in a one-dimensional direction that requires high resolution, and can be realized by, for example, a Levenson-type phase shift mask. In the case of the Levenson-type phase shift mask, the white portion and the gray portion in the figure have phases inverted from each other, and a high-contrast periodic exposure pattern is formed by two-beam interference exposure due to the phase inversion effect. The mask is not limited to the Levenson-type phase shift mask, and may be any mask as long as it forms such an exposure distribution.

The pitch of this exposure pattern is 0.2 μm, and the exposure pattern forms the exposure dose distribution shown in FIG. 18A by a line and space pattern in which each line and space has a line width of 0.1 μm. Is done. As a pattern and a mask for forming a multi-value pattern, a mask on which a pattern similar to a circuit pattern to be finally formed is drawn. In this case, a mask on which the gate pattern shown in FIG. 19B is drawn is used.

As described above, the portion composed of the fine lines of the gate pattern is a pattern having a resolution lower than that of a normal exposure. Therefore, on the resist, the two lines of the fine lines are not resolved and a uniform distribution having a weak intensity is obtained. On the other hand, the pattern at both ends of the fine line is resolved as a pattern having a high intensity because the line width is within the range of the resolving power by the normal exposure of the apparatus.

Therefore, when the pattern and the mask shown in FIG. 19B are exposed, a multi-level exposure distribution shown in FIG. 18B is formed. In this example, the pattern to be formed has a light transmission type light exposure distribution, but a light shielding type pattern can also be formed by using a mask as shown in FIG. The light-shielding type pattern can be realized by using a mask that transmits light to portions other than the pattern and shields light from the pattern portion.

In the case of a light-shielding type pattern, a pattern having a resolution higher than the resolution blocks light, and the exposure amount distribution becomes zero. Since an exposure amount that is half of the distribution is distributed, a multivalued exposure amount distribution is formed.

The principle of the double exposure described above is summarized as follows. The periodic pattern exposure area that is not fused with the exposure pattern of the normal exposure, that is, the periodic exposure pattern equal to or less than the exposure threshold of the resist disappears by development. 2. Regarding the pattern area of the normal exposure performed with the exposure amount equal to or less than the exposure threshold value of the resist, one of the desired circuit patterns having the resolution of the periodic pattern exposure, which is determined by a combination of the exposure patterns of the normal exposure and the periodic pattern exposure. An exposure pattern as a part is formed. 3. An exposure pattern corresponding to the mask pattern is formed in the pattern area of the normal exposure performed with the exposure amount equal to or more than the exposure threshold value of the resist. Further, as an advantage of the multiple exposure method, a large depth of focus can be obtained by performing a two-beam interference exposure using a phase shift mask or the like for a periodic pattern exposure requiring the highest resolution. In the above description, the order of the periodic pattern exposure and the normal exposure is the order of the periodic pattern exposure, but may be reversed or simultaneous.

The "normal exposure" here is an exposure method capable of exposing an arbitrary pattern although the resolution is lower than that of the periodic pattern exposure. As a typical example, the pattern of a mask is projected by a projection optical system. Projection exposure capable of projecting

The pattern exposed by the normal exposure is
It contains a fine pattern with a resolution lower than the resolution (hereinafter referred to as a normal exposure pattern). As a result, the image intensity has a multi-value distribution as described above. The periodic pattern exposure forms a periodic pattern having the same line width as the fine pattern portion of the normal exposure. For this periodic pattern exposure, a Levenson-type phase shift mask or the like is used. One example is shown in FIG. By the double exposure shown in FIG. 18, the mask pattern to be transferred to the positive resist in which the brightness of the pattern is reversed becomes as shown in FIG.
By exposing the normal exposure pattern and the periodic pattern shown in FIG. 1 to the same position, it becomes possible to obtain a fine pattern which is a composite image of the pattern.

As described above, a pattern to be finally formed is exposed as a normal exposure pattern. Since the normal exposure pattern includes fine lines of a resolution or less, a high-resolution periodic pattern is exposed at the same position. By
The resolution of the normal exposure pattern can be improved, and finally a desired pattern including fine lines having a resolution lower than the resolution can be formed.

As described above, in order to improve the resolution of the normal exposure pattern of FIG. 1, by exposing the high resolution periodic pattern of FIG. 1 to the same position, only the normal exposure pattern of FIG. A fine line that could not be created can be created by combining it with a high-resolution periodic pattern.

[0023]

Generally, a circuit pattern uses a minimum fine line called a design rule as a unit of line width, and a line width error is strictly controlled with this line width. Larger line widths are easier to resolve and have less severe line width control. When transferring an arbitrary circuit pattern onto a semiconductor substrate, the line width accuracy of fine lines is important, and the minimum fine line is generally ± 10% of the line width.
% Or less, and in some cases only ± 5% or less.

Further, since the pitch often differs depending on the pattern, it is more difficult to control the line width of fine lines. Because, even for patterns with fine lines of the same line width,
Those with a large pitch are relatively easily resolved, and those with a small pitch are difficult to resolve. Therefore, even if patterns have fine lines having the same line width, if the patterns have different pitches, the line widths of the fine lines are not uniform.

According to the double exposure method, a reticle having a pattern similar to a circuit pattern is used as a reticle for normal exposure, but periodic pattern exposure focuses only on fine lines of this circuit pattern. This periodic pattern exposure
Pattern (A) in which only fine lines are extracted from the circuit pattern
Then, a periodic pattern including the fine line extraction pattern (A) (having the same or greater number of cycles than A) including the fine line extraction pattern (A) is exposed. Although there is a method that does not use a reticle for this periodic pattern exposure, a method using a reticle is used here.

Here, a plurality of patterns arranged on the reticle for normal exposure often include patterns having different pitches as described above. Since the normal exposure pattern is similar to the circuit pattern,
When the circuit pattern is determined, it is automatically determined. for that reason,
As the periodic pattern, a pattern matching this normal exposure pattern is used.

In this case, it is desirable that the pitch of the periodic pattern is equal to the pitch of the normal exposure pattern. Further, the line width constituting the pitch of the periodic pattern is not particularly limited, and may be the same as the line width of the normal exposure pattern, or may be different. As described above, since the line width forming the pitch of the periodic pattern is not particularly determined,
There were various cases where the line width was the same or different.

In the usual double exposure, all normal exposure patterns in the same reticle are exposed at a certain exposure amount. Then, the periodic pattern exposure is performed while adjusting the exposure amount of the periodic pattern exposure so that the minimum line width for which the line width control is strict becomes a predetermined line width. In double exposure, since a periodic pattern corresponding to the normal exposure pattern is created, depending on the line width of the periodic pattern,
In some cases, the line width of the fine lines of the finally obtained composite image is not uniform in all patterns.

Therefore, when the line width constituting the pitch of the periodic pattern is not particularly determined, a phenomenon occurs in which the optimum exposure amount differs for each pattern or the line width changes with respect to the exposure amount depending on how the line width is taken. As a result, the exposure range common to all the patterns on the same mask may be narrowed.

As described above, since the exposure characteristic of each pattern changes depending on the line width constituting the pitch of the periodic pattern, all the optimum exposure amounts are made uniform and the line width change with respect to the exposure amount is made as equal as possible. In order to secure a wide exposure amount range common to all the patterns, it is very important to determine the line width forming the optimal periodic pattern.

Hereinafter, the problem in this respect will be described in detail with reference to FIGS. 2 and 3. FIG. 2 shows a case where a negative resist for forming a pattern in the light transmitting portion is used, and a case where the two uppermost design patterns (pattern 1 and pattern 2) are to be transferred onto a wafer. here,
The normal exposure pattern in FIG. 2 is a pattern similar or similar to the design pattern, and it is originally necessary to consider the magnification of the exposure apparatus, but here, it is shown as a magnification of 1 for easy understanding. The periodic pattern shown in FIG. 2 focuses on the fine line portions of the normal pattern similar or similar to the design pattern, and has the same pitch as the pattern obtained by extracting only these fine lines. Then, the number of periods is set to the same number or more than the pattern from which only the fine lines are extracted.

As described above, it has been described that the normal exposure pattern is created from the design pattern and the periodic pattern is created from the normal exposure pattern. However, in this periodic pattern, although the pitch of the periodic pattern and the number of periods can be determined from the normal exposure pattern, the line width constituting the pitch of the periodic pattern is not determined at all. At present, a positive resist that forms a pattern with a light-shielding portion is more common. Therefore, an example of a positive resist is shown in FIG. 3, and a problem caused by how to obtain a line width forming a pitch of a periodic pattern will be further described. . Similarly, FIG. 3 shows a case where it is desired to transfer the two uppermost patterns as design patterns onto a wafer.

The pattern 1 of the normal exposure pattern has a pitch P
1 and is composed of one type of fine line (line width L). On the other hand, the pattern 2 of the normal exposure pattern has a pitch P2 of 2
It is composed of different types of line widths (line width L · 2L). Since the line widths L of the fine lines in the pattern 1 and the pattern 2 of the normal exposure pattern are the same, first, a case is considered in which the line widths of the periodic patterns have the same line width even if their pitches are different. For example, when the pitch P1 is 2L and the pitch P2 is 3L, 1) when the line width of the periodic pattern is 1L for both the patterns 1 and 2, and 2) when the line width of the periodic pattern is 1.5L for both the patterns 1 and 2. Is the case. 2 and 3 show the case 1).

FIG. 4 shows the relationship between the exposure amount for section A in FIG. 3 and the line width of section A in the composite image created by double exposure. As shown in FIG. 3, the line width of the periodic pattern of pattern 1 was L1, and the line width of the periodic pattern of pattern 2 was L2. FIG. 4 shows that the pitch of pattern 1 is 2L and the pitch of pattern 2 is 3L (L = 130n).
1) When both the pattern 1 and the pattern 2 have a line width of 1L (L1 = L2 = 1L) 2) Both the pattern 1 and the pattern 2 have a line width of 1.5L Case (L1 = L2 = 1.5L) Two cases are shown.

FIG. 4 shows that the exposure amount at which the fine line L of the pattern 2 becomes the design line width (L = 130 nm) is set as a reference exposure amount, and this reference exposure amount is set at the center of the graph. The width change was plotted. A dashed line indicates a change in pattern 1 and a solid line indicates a change in pattern 2. In order to form all the patterns with the same exposure, the line widths of pattern 1 and pattern 2 having the same exposure should both be equal. That is, the two graphs should exactly match or be very close. However, FIG.
In both graphs, since the two lines are largely separated from each other, it can be seen that the line widths of the pattern 1 and the pattern 2 are different at the same exposure amount, that is, the optimum exposure amount which becomes the designed line width is shifted.

This is because, when patterns having different pitches on the same mask are formed, if the line widths of the periodic patterns are equal in all the patterns, it is impossible to equalize the optimum exposure amount for each pattern. Is shown. Further, in both graphs 1) and 2), when comparing the slopes of the solid line and the broken line graph, the slope of the solid line (pattern 2) is steeper.
It can be seen that the line width change is larger with respect to the exposure amount change. In other words, the line width change with respect to the exposure amount changes for each pattern. In other words, if the allowable range of the line width variation is within 10% of the design line width, the optimum exposure amount and the allowable region are different for each pattern, so that the exposure amount range common to the two patterns becomes very narrow. It is a problem.

As described above, when a periodic pattern having the same line width is used, the optimum exposure amount and the line width change with respect to the change in the exposure amount are different for each pattern. It becomes very narrow. As described above, since the exposure characteristic for each pattern changes depending on the line width of the periodic pattern, it is necessary to optimize the optimal exposure for all patterns and the relationship between the exposure variation and the line width variation. It is important to determine the line width of a proper periodic pattern.

Accordingly, the present invention solves the above-mentioned problems, makes it possible to match the optimum exposure amount between patterns, and to equalize the line width change with respect to the exposure amount between patterns, thereby widening the exposure amount range common to patterns. An object of the present invention is to provide a mask for performing multiple exposure that can be taken, an exposure method using the mask, an exposure apparatus, and a device manufacturing method.

[0039]

In order to achieve the above object, the present invention provides a mask for performing multiple exposures as described in the following (1) to (16), an exposure method using the mask, and an exposure method. An apparatus and a device manufacturing method are provided. (1) Multiple exposure including exposure of a first pattern having a periodic pattern and exposure of a second pattern having a plurality of fine line groups having the same line width and different intervals between line widths are performed on the substrate to be exposed. Wherein the first pattern has a plurality of periodic patterns having the same ratio between a line width overlapping with one of the fine line groups and an interval between the line widths. Mask. (2) The mask according to (1), wherein the line widths of the plurality of periodic patterns of the first pattern are equal to each other. (3) The mask according to the above (1) or (2), wherein the first pattern having the periodic pattern has a plurality of pattern blocks. (4) The mask according to any one of (1) to (3), wherein the second pattern having the fine line is a pattern similar or similar to a design pattern. (5) The above (1) to (4), wherein the second pattern having the fine lines has a plurality of line widths.
The mask according to any one of the above. (6) The mask according to any one of the above (1) to (4), wherein the second pattern having the fine line is configured by a pattern in which patterns having different line widths are separated from each other. (7) The mask according to any one of the above (1) to (4), wherein the second pattern having the fine lines is constituted by a pattern in which the directions of the fine lines are mixed. (8) The mask according to any one of (1) to (4), wherein the second pattern having the fine lines has an L-shaped pattern in which the directions of the fine lines are orthogonal. (9) The mask according to any one of the above (1) to (4), wherein the second pattern having the fine line has a pattern in which the direction of the fine line is oblique. (10) An exposure method using the mask according to any one of (1) to (9) and exposing and transferring the mask pattern onto a photosensitive substrate. (11) The exposure using the first pattern is a pattern exposure with a certain image contrast, and the exposure using the second pattern is a pattern exposure with a lower image contrast than the first pattern. The exposure method according to 10). (12) The pitch P of the periodic pattern of the mask,
When the wavelength of the exposure light is λ, the numerical aperture of the projection optical system used for exposing and transferring the mask pattern onto the photosensitive substrate is NA, and k1 = P / (λ / NA), 0.5 ≦ k1 ≦ The exposure method according to the above (10) or (11), wherein the relationship of 1.0 is satisfied. (13) An exposure apparatus using the mask according to any one of claims 1 to 9 and having a multiple exposure mode for projecting a pattern of the mask onto a photosensitive substrate by a projection optical system. (14) The exposure by the first pattern is a pattern exposure composed of fine lines, and the exposure by the second pattern is a pattern exposure having a lower image contrast than that of the first pattern, and the projection exposure is performed. The exposure apparatus according to the above (13), wherein: (15) The pitch P of the periodic pattern of the mask, the wavelength of the exposure light is λ, and the numerical aperture of the projection optical system used when exposing and transferring the mask pattern onto the photosensitive substrate is N.
A, and when k1 = P / (λ / NA), the configuration is such that the relationship of 0.5 ≦ k1 ≦ 1.0 is satisfied. Exposure apparatus according to the above. (16) The pattern on the reticle surface is transferred onto the wafer surface by the exposure method according to any one of (10) to (12) or the exposure apparatus according to any one of (13) to (15). Forming a device on the wafer through a development process.

[0040]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In an embodiment of the present invention,
In the case where double exposure of a periodic pattern and a normal exposure pattern is performed, and a plurality of patterns are on the same mask and the plurality of patterns are created by exposure under the same condition, multiple exposure having the above configuration is performed. The above-described problem can be achieved by using a mask for the purpose.

That is, irrespective of the pitch of the periodic patterns, by making the duties equal in all the periodic patterns, not only can the optimum exposure amount of each pattern be made uniform and a good composite image can be formed, but also the exposure The amount range can be extended. The fact that the duties are equal means that the ratio between the line width and the interval constituting the pitch is made equal.

For example, in the case where two patterns of pattern 1 (pitch P1) and pattern 2 (pitch P2) are mixed on the same reticle as the normal exposure patterns described in the above-mentioned problem, as shown in FIG. , The ratio between the line width and the interval is made equal regardless of the pitch. Here, FIG.
The pitch of pattern 1 is P1, the line width of the periodic pattern is L1, the interval is S1, and the pitch of pattern 2 is P2.
When the line width of the periodic pattern is L2 and the interval is S2,
It is configured to satisfy the following equation. L1: S1 = L2: S2 (P1 = L1 + S1 P2 = L
2 + S2) As described above, when a plurality of patterns are formed on the same mask, a good synthesized image can be obtained with an optimal exposure amount by using a periodic pattern having the same duty regardless of the pitch of the patterns. Instead, it is possible to widen the exposure amount range common to all patterns.

It is known that the optimum value of the optimum duty of the periodic pattern changes depending on the exposure ratio when the line width / periodic pattern forming the pattern and the normal exposure pattern are combined. Therefore, it is desirable to determine the line width ratio of this periodic pattern according to the conditions for actual exposure, but it is still the same as using a periodic pattern in which all duties are equal. Further, here, the light transmitting portion is expressed as a line width, and the light shielding portion is expressed as an interval. However, even if the light shielding portion is expressed as a line width and the light transmitting portion is formed as an interval, the object and effect of the present invention are not changed. . The periodic pattern used here may be a phase shift mask in which the phase is inverted between 0 and 180 degrees, and the same effect is obtained even when the periodic pattern is formed by interference of two plane waves.

[0044]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below, but before that, in order to facilitate understanding of these embodiments, a flowchart of the double exposure method of FIG. Keep it. FIG. 6 shows the flow of each block of the periodic pattern exposure, the normal pattern exposure, and the development. However, the order of the periodic pattern exposure and the normal pattern exposure may be the same or the reverse, and a plurality of times may be performed. When the exposure step is included, the exposure step can be performed alternately. In addition, a step of performing precise alignment is performed between each exposure step, but details regarding this processing are omitted.

It should be noted that a high contrast image can be obtained by the periodic pattern exposure and a low contrast image can be obtained by the normal exposure pattern.
Using a krF excimer stepper of nm, a periodic pattern is devised when performing double exposure of periodic pattern exposure and normal pattern exposure. The present invention is not limited to the embodiments described below, and can be variously modified without departing from the gist of the present invention.

[Embodiment 1] Embodiment 1 of the present invention relates to a case where a pattern is formed by a light shielding portion, and a case where a normal exposure pattern is two patterns having the same pitch will be described with reference to FIG. . FIG. 7 shows a periodic pattern and a normal exposure pattern that are actually used, and a positional relationship of double exposure thereof as a composite pattern. The purpose is to finally obtain a pattern having the same shape as the normal exposure pattern in FIG. 7 by combining these two patterns.

The pitch of the pattern 1 and the pattern 2 of the normal exposure pattern shown in FIG. 7 are equal (P1) and include fine lines of the same line width. In order to make the optimal exposure amounts of two types of patterns having the same pitch coincide with each other, and to take as wide an exposure amount range that the line width change with respect to the exposure amount is within the standard, regardless of the pattern pitch, As shown in FIG. 7, a periodic pattern having the same ratio between the line width and the interval (equal duty) is used in all the patterns. Here, as shown in FIG. 7, the pitch of pattern 1 is P1, the line width of the periodic pattern is L1, and the interval is S1.
When the pitch of the pattern 2 is P1, the line width of the periodic pattern is L2, and the interval is S2, the following relationship is satisfied. L1: S1 = L2: S2 (P1 = L1 + S1 P1 = L
2 + S2) Here, the pitch of both patterns is 3L (L = 13
0 nm) and the line width of the normal exposure pattern is 1 L for pattern 1 and 1 L and 2 L for pattern 2 as an example.
The effect will be described with reference to FIG. FIG. 8 shows the relationship between the exposure amount and the line width of the A section in FIG. 7 in the composite image created by the double exposure. 1) shows the case where the duties of the two periodic patterns are different. 2) shows the case where the duties of the two periodic patterns are equal.

The specific dimensions are pattern 1 and pattern 2
In both cases, the pitch is 3L (L = 130nm). 1) The line width of the periodic pattern of pattern 1 is 1.5L and the interval is 1.5L (L1: S1 = 1: 1) Line width is 1L, interval is 2L (L
2: S2 = 1: 2) 2) The line width of the periodic pattern of pattern 1 is 1.5L, the interval is 1.5L (L1: S1 = 1: 1) The line width of the periodic pattern of pattern 2 is 1.5L, The interval is 1.5 L (L2: S2 = 1: 1).

FIG. 8 shows an exposure amount where the fine line L of the pattern 2 has reached the design line width (L = 130 nm) as a reference exposure amount, and this reference exposure amount is set at the center of the graph. The width change was plotted. A dashed line indicates a change in pattern 1 and a solid line indicates a change in pattern 2.

In order to form all patterns with the same exposure, the line widths of pattern 1 and pattern 2 having the same exposure should both be equal. In 2) of FIG. 8, 2
The lines are exactly overlapped with each other, so that the optimal exposure amounts of the two patterns are the same, and the relationship between the exposure amount and the line width is also equal. In other words, when the duty of the two periodic patterns is equal, the exposure characteristic is very good, and not only can the optimum exposure of all the patterns match, but the relationship between the exposure and the line width change is also uniform. The exposure range can be expanded most.

On the other hand, since the two lines in the graph of 1) in FIG. 8 are largely separated from each other, the line widths of the pattern 1 and the pattern 2 are different at the same exposure amount, that is, the optimum exposure amount becomes a predetermined line width. It can be seen that is shifted. In the graph of 1) in FIG. 8, when the slopes of the solid line and the broken line are compared, the slope of the broken line (pattern 1) is steeper. It can be seen that the width change is large. In the case of 1) in FIG. 8, the line width change with respect to the change in the exposure amount differs for each pattern.

In other words, when the duty of the two periodic patterns is different, when the allowable range of the line width variation is within 10% of the design line width, the optimum exposure amount and the allowable area are different for each pattern. The exposure amount range common to the patterns becomes very narrow. Even if the line width is corrected so that the line widths of the two patterns are equal at the reference exposure amount so that the optimum exposure amounts match,
Since the amount of change in line width when deviating from the exposure amount differs for each pattern, the exposure amount range common to the patterns becomes narrow.

As can be seen from the above, in the case where a pattern is created by the light-shielding portion and two patterns having the same pattern pitch are used, the pattern having the same duty as the periodic pattern is used. Thus, not only can the line widths of all the patterns be matched, but also the line width change with respect to the exposure can be matched for all the patterns, and the exposure range common to all the patterns can be improved most.

In the first embodiment, the best results were obtained when the duty ratio L: S = 1: 1 in all the patterns. However, the duty ratio is not limited to 1: 1. In the present invention, it is important to make the duty of all the periodic patterns equal.

[Embodiment 2] In Embodiment 2 of the present invention, as in Embodiment 1, a case where a pattern is created by a light-shielding portion, and FIG. It will be described using FIG.

FIG. 9 shows the actually used periodic pattern and the normal exposure pattern, and the positional relationship of double exposure thereof as the composite pattern of FIG. This figure 9
The purpose is to finally obtain a pattern having the same shape as the normal exposure pattern in FIG. 9 by synthesizing these two patterns.

Although the pitches of the pattern 1 and the pattern 2 of the normal exposure pattern shown in FIG. 9 are different from each other, the pattern includes fine lines (L) having the same line width. In order to make the optimum exposure amounts of the two types of patterns having different pitches coincide with each other as much as possible, and to make the exposure amount range in which the line width change with respect to the exposure amount is within the standard as wide as possible, it is necessary to set the optimum exposure amount regardless of the pattern pitch. Instead, as shown in FIG. 9, a periodic pattern in which the ratio between the line width and the interval is equal (the duty is equal) is used in all the patterns. Here, as shown in FIG. 9, when the pitch of pattern 1 is P1, the line width of the periodic pattern is L1 and the interval is S1, and the pitch of pattern 2 is P2, the line width of the periodic pattern is L2 and the interval is S2, It is configured to satisfy the relationship of the expression. L1: S1 = L2: S2 (P1 = L1 + S1 P2 = L
2 + S2) Here, the case where the pitch of pattern 1 is 2L and the pitch of pattern 2 is 3L (L = 130nm), and the case where the line width of the normal exposure pattern is 1L for pattern 1 and 1L and 2L for pattern 2 Next, the effect will be described with reference to FIG. FIG. 10 shows a composite image created by double exposure,
10 illustrates a relationship between an exposure amount and a line width of the A section in FIG. 9. 1) and 2) in FIG. 10 show the case where the duties of the two periodic patterns are different, and 3) in FIG. 10 show the case where the duties of the two periodic patterns are equal. Specifically, this is the case where the pitch of pattern 1 is 2L and the pitch of pattern 2 is 3L (L = 130nm). 1) The pitch P1 of pattern 1 is 2L and the periodic pattern is L
1: S1 = 1.5L: 0.5L = 3: 1 Pitch P2 of pattern 2 is 3L, periodic pattern is L2:
S2 = 1.5L: 1.5L = 1: 1 2) Pitch P1 of pattern 1 is 2L, periodic pattern is L
1: S1 = 1L: 1L = 1: 1 Pitch P2 of pattern 2 is 3L, periodic pattern is L2:
S2 = 2L: 1L = 2: 1 3) Pitch P1 of pattern 1 is 2L, periodic pattern is L
1: S1 = 1L: 1L = 1: 1 Pitch P2 of pattern 2 is 3L, periodic pattern is L2:
The case of three types of periodic patterns of S2 = 1.5L: 1.5L = 1: 1 is shown.

In FIG. 10, the exposure amount at which the fine line L of the pattern 2 has reached the design line width (L = 130 nm) is set as the reference exposure amount, and this reference exposure amount is set at the center of the graph. The width change was plotted. The broken line is pattern 1,
The solid line indicates the change of the pattern 2.

In order to form all patterns with the same exposure, both the pattern 1 and the pattern 2 having the same exposure should have the same line width. In 3) of FIG.
Since the difference between the two lines is the smallest, and the inclination of the two lines is the smallest, the optimum exposure amounts of both patterns are relatively equal, and the exposure amount and the line width The relationship is also equal. In other words, when the duty of the two periodic patterns is equal, the exposure characteristic is very good, and not only can the optimum exposure of all the patterns match, but the relationship between the exposure and the line width change is also uniform. It is possible to extend the exposure range common to all patterns.

On the other hand, since the two lines in the graphs 1) and 2) in FIG. 10 are largely separated from each other, the line widths of the pattern 1 and the pattern 2 are different at the same exposure amount, that is, a predetermined line width is obtained. It can be seen that the optimum exposure amount is shifted. Further, in the graphs 1) and 2) of FIG. 10, when comparing the slopes of the solid line and the broken line, the slope of the solid line (pattern 2) is steeper in 1) of FIG. Then, the slope of the broken line (pattern 1) is steeper. As described above, in the cases 1) and 2) of FIG. 10, the line width change with respect to the change in the exposure amount differs for each pattern.

That is, when the duty of the two periodic patterns is different, when the allowable range of the line width variation is within 10% of the design line width, the optimum exposure amount and the allowable area are different for each pattern. The exposure amount range common to the patterns becomes very narrow. Even if the line width is corrected so that the line widths of the two patterns are equal at the reference exposure amount so that the optimum exposure amounts match,
Since the amount of change in line width when deviating from the exposure amount differs for each pattern, the exposure amount range common to the patterns becomes narrow.

As can be seen from the above description, in the case where a pattern is formed in the light shielding portion and two patterns having the same pattern pitch are used, the pattern having the same duty as the periodic pattern is used. Thus, not only can the line widths of all the patterns be matched, but also the line width change with respect to the exposure can be matched for all the patterns, and the exposure range common to all the patterns can be improved most.

Here, in all the patterns, only the case where the duty L: S = 1: 1 has been described. However, the duty is not limited to 1: 1. It is possible to make the duty of all the periodic patterns equal. is important. Regarding the optimum duty, it is known that the optimum value varies depending on the exposure ratio when the line width / periodic pattern forming the pattern and the normal exposure pattern are combined, and the like. Therefore, it is desirable to determine the line width ratio of this periodic pattern according to the conditions for actual exposure.
Basically, when a pattern is formed by the light shielding portion, the wider the line width of the light transmitting portion, the higher the contrast. It can be seen from the first embodiment and the second embodiment that, even when the pitch is the same or different, it is most effective to use a periodic pattern having the same duty for all patterns regardless of the pitch.

[Embodiment 3] In Embodiment 3 of the present invention, as in Embodiment 1, the normal exposure pattern is two patterns having the same pitch, and FIG. It will be described using FIG. FIG. 11 shows a periodic pattern and a normal exposure pattern that are actually used, and a positional relationship in which they are double-exposed as a composite pattern. The purpose is to finally obtain a pattern having the same shape as the normal exposure pattern of FIG. 11 by combining the two patterns of FIG. 11 and. The pitch of the pattern 1 and the pattern 2 of the normal exposure pattern shown in FIG. 11 are equal, and the pattern 1 is a pattern composed of one kind of fine line and the pattern 2 is composed of two kinds of line widths including the fine line.

In order to make the optimum exposure amounts of two types of patterns having the same pitch coincide with each other and to make the exposure range common to the patterns as wide as possible, in which the line width change with respect to the exposure amount change is within the standard. Regardless of the line width of the normal exposure pattern, as shown in FIG. 11, the line width ratio relationship between the light shielding portion and the light transmitting portion is equal in all patterns.
It is necessary to use a periodic pattern (equal in duty). Here, as shown in FIG. 11, when the pitch of pattern 1 is P1, the line width of the periodic pattern is L1, and the interval is S1, and the pitch of pattern 2 is P1, the line width of the periodic pattern is L2, and the interval is S2. It is configured to satisfy the relationship of the expression. L1: S1 = L2: S2 (P1 = L1 + S1 P2 = L
2 + S2) As described above, when a plurality of patterns having the same pitch are present on the same mask in the case where the pattern is formed by the light transmitting portion, by using a periodic pattern having the same duty, each pattern at the reference exposure amount is used. Not only can the line width difference be made as small as possible, but also the line width change with respect to the exposure can be matched for all patterns, and the common exposure range can be maximized.

[Embodiment 4] Embodiment 4 of the present invention relates to a case where a pattern is formed by a light shielding portion. In a normal exposure pattern, two types of patterns having different pitches are formed on the same mask and are fine. A case of a pattern in which line directions are mixed will be described with reference to FIG. This figure 1
Reference numeral 2 denotes a periodic pattern actually used to obtain a combined pattern by double exposure and a normal exposure pattern in FIG. The purpose is to finally obtain a pattern having the same shape as the normal exposure pattern in FIG. 12 by combining the two patterns in FIG. 12 and the two patterns.

The pitch of the pattern 1 and the pattern 2 of the normal exposure pattern shown in FIG.
Is a type of fine line, and pattern 2 is a pattern composed of two types of line widths including the fine line. In the periodic pattern shown in FIG. 12 used for resolving the fine line, the periodic directions of the two patterns are orthogonal to each other in order to match the direction of the fine line. However, the line width of this periodic pattern can be considered as in the second embodiment.

That is, in order to make the optimum exposure amounts of two types of patterns having the same pitch coincide with each other and to make the exposure range common to the patterns as wide as possible, in which the line width change with respect to the exposure amount change is within the standard, FIG. As shown in FIG. 12, it is necessary to use a periodic pattern having the same line width ratio between the light shielding portion L1 and the light transmitting portion S1 of the periodic pattern in all the patterns, that is, having the same duty.
However, the direction of the period is made to coincide with the direction of the fine line. Here, as shown in FIG. 12, when the pitch of pattern 1 is P1, the line width of the periodic pattern is L1, and the interval is S1, and the pitch of pattern 2 is P2, the line width of the periodic pattern is L1, and the interval is S1, It is configured to satisfy the relationship of the expression. L1: S1 = L2: S2 (P1 = L1 + S1 P2 = L
2 + S2) As described above, even when a plurality of patterns having different pitches and different fine line directions are present on the same mask when a pattern is formed by the light shielding portion, by using a periodic pattern having the same duty, Not only can the line width difference for each pattern at the reference exposure amount be minimized, but also the line width change with respect to the exposure amount can be matched for all patterns, and the common exposure range can be improved most. . In the present embodiment, the pitches of the two patterns are different. Of course, even when the pitch is the same, it is necessary to use a periodic pattern having the same duty.

[Embodiment 5] Embodiment 5 of the present invention relates to a case where a pattern is formed by a light-shielding portion, in which an ordinary exposure pattern includes an L-shaped pattern in which the direction of fine lines is orthogonal. 13 will be described. FIG. 13 shows a periodic pattern and a normal exposure pattern actually used to obtain a combined pattern by double exposure.
The purpose is to finally obtain a pattern having the same shape as the normal exposure pattern in FIG. 13 by synthesizing the two patterns in FIG. 13 and the two patterns.

The pitch between pattern 1 and pattern 2 of the normal exposure pattern shown in FIG.
Is a type of fine line, and pattern 2 is a pattern composed of two types of line widths including the fine line. Periodic pattern used for resolving fine lines In FIG. 13, the periodic pattern of pattern 1 is L-shaped, and the periodic directions are orthogonal to each other in order to match the direction of the fine lines. However, even in this case, the line width of the periodic pattern can be considered in the same manner as in the second embodiment.

That is, in order to make the optimum exposure amounts of two types of patterns having different pitches coincide with each other, and to make the exposure range common to the patterns as wide as possible, in which the line width change with respect to the exposure amount change is within the standard, FIG. As shown in FIG. 13, it is necessary to use a periodic pattern having the same line width ratio between the light-shielding portion and the light-transmitting portion of the periodic pattern in all the patterns, that is, having the same duty. However,
The direction of the period coincides with the direction of the fine line. Here, Figure 1
As shown in FIG. 3, the pitch of pattern 1 is P1, the line width of the periodic pattern is L1, the interval is S1, and the pitch of pattern 2 is P1.
2. When the line width of the periodic pattern is L1 and the interval is S1, the configuration is such that the following equation is satisfied. L1: S1 = L2: S2 (P1 = L1 + S1 P2 = L
2 + S2) As described above, in the case where a pattern is formed by the light shielding portion, even when a plurality of patterns including an L-shaped pattern having different pitches and different fine line directions are present on the same mask,
By using periodic patterns with the same duty, not only the line width difference between patterns at the reference exposure amount can be made as small as possible, but also the line width change with respect to the exposure amount can be matched for all patterns, and the common exposure amount The range can be improved most. It can be said that the same effect is obtained even when the contact hole portion is connected as shown in FIG.

[Embodiment 6] Embodiment 6 of the present invention relates to a case where a pattern is formed by a light shielding portion, and shows a case where a fine line direction of a normal exposure pattern includes an oblique pattern. It will be described using FIG. FIG. 15 shows an example of FIG. 1 actually used to obtain a composite pattern by double exposure.
5 and the normal exposure pattern of FIG. The purpose is to finally obtain a pattern having the same shape as the normal exposure pattern of FIG. 15 by combining these two patterns.

In the normal exposure pattern shown in FIG. 15, fine lines extending in two directions have different pitches. As shown in FIG. 15, the pitch in the direction 1 is P1, the line width of the periodic pattern is L1 · interval S1, the pitch in the direction 2 is P2, and the line width of the periodic pattern is L2 · S2. The periodic pattern used for resolving the fine line In FIG. 15, the periodic pattern includes an oblique direction in order to match the direction of the fine line. However, even in this case, the line width of the periodic pattern can be considered in the same manner as in the second embodiment.

In other words, in order to make the optimal exposure doses of patterns having two kinds of directions having different pitches coincide with each other and to make the exposure dose range common to the patterns in which the line width change with respect to the exposure dose change is within the standard as wide as possible. As shown in FIG. 15, the line width ratio relationship between the light shielding portion and the light transmitting portion is equal.
That is, it is necessary to use a periodic pattern having the same duty. However, the direction of the period is made to coincide with the direction of the fine line, and is configured so as to satisfy the following equation. L1: S1 = L2: S2 (P1 = L1 + S1 P2 = L
2 + S2) As described above, even when a plurality of patterns including a pattern having a different pitch and a diagonal fine line are present on the same mask when a pattern is formed by the light shielding portion, a periodic pattern having the same duty is used. By using
Not only can the line width difference for each pattern at the reference exposure amount be minimized, but also the line width change with respect to the exposure amount can be matched for all patterns, and the common exposure range can be improved most. . Of course, the same effect can be said to be obtained even when the contact hole portion is connected to this pattern.

[Embodiment 7] Embodiment 7 of the present invention relates to a case where a pattern is formed by a light-shielding portion and a case where a normal exposure pattern is an integral multiple of the pitch of a periodic pattern with reference to FIG. explain. FIG. 16 shows, as a composite pattern, a periodic pattern and a normal exposure pattern that are actually used, and a positional relationship in which they are double-exposed. By combining these two patterns,
Finally, the purpose is to obtain a pattern having the same shape as the normal exposure pattern shown in FIG.

As shown in FIG. 16, the pitches of pattern 1 and pattern 2 are different. In the periodic pattern, the pitch of pattern 1 is P1, the pitch of the periodic pattern of pattern 2 is P2, and the pitch of the normal exposure pattern is P1.
It is twice as large as 2. As described above, even when a pattern in which the pitch between the normal exposure pattern and the periodic pattern has an integer multiple relationship is included, the same relationship holds.

That is, in order to make the optimum exposure amounts of two types of patterns having different pitches coincide with each other, and to make the exposure range common to the patterns as wide as possible, in which the line width change with respect to the exposure amount change is within the standard, FIG. As shown in FIG. 16, in all patterns, the ratio between the line width and the interval of the periodic pattern is equal, and the following relationship is satisfied. That is, it is necessary to use a periodic pattern having the same duty. L1: S1 = L2: S2 (P1 = L1 + S1 P2 = L
2 + S2) As described above, when the patterns are formed by the light transmitting portions, the pitches are different from each other, and even if a pattern in which the relationship between the pitch of the normal exposure pattern and the pitch of the periodic pattern is an integral multiple exists on the same mask, the duty of the By using the same periodic pattern, not only the line width difference for each pattern at the reference exposure amount can be made as small as possible, but also the line width change with respect to the exposure amount can be matched for all patterns, and the common exposure amount range It can be improved the most.

In summary, in an exposure method for performing double exposure of a normal exposure pattern and a periodic pattern, regardless of the pitch of the periodic pattern, the “equal duty” cycle, which is the ratio of the line width to the interval of the periodic pattern, By using patterns, it is possible to make the optimal exposure amounts of all the patterns coincide, and to make the line width change with respect to the exposure amounts uniform, thereby making it possible to widen the exposure amount range common to all the patterns. . And even if the normal exposure pattern is configured with a plurality of line widths, even if patterns with different line widths are separated on the same mask, even if the directions are mixed, By using a periodic pattern having the same duty, the above-described object of the present invention can be achieved.

Next, a high-resolution exposure apparatus using a mask in each of the above embodiments will be described. FIG.
FIG. 5 is a schematic view showing a high-resolution exposure apparatus capable of performing both exposure for two-beam interference of a periodic pattern and ordinary projection exposure to which the above-described embodiments can be applied. In FIG. 17, 221
Is a KrF or ArF excimer laser, 222 is an illumination optical system, 223 is a mask (reticle), 224 is a mask stage, 227 is a circuit pattern of the mask 223 on the wafer 2.
A projection optical system 225 for reducing and projecting on the reference numeral 28 is a mask (reticle) changer. The stage 224 has a normal reticle and the above-mentioned Levenson-type phase shift mask (reticle), edge shifter type mask (reticle) or phase shifter. It is provided for selectively supplying one of the periodic pattern masks (reticles) that is not provided.

Reference numeral 229 in FIG. 17 denotes one XYZ stage shared by the two-beam interference exposure and the projection exposure. This stage 229 is movable in a plane perpendicular to the optical axis of the optical system 227 and in the direction of the optical axis. The position in the XY directions is accurately controlled using a laser interferometer or the like. The apparatus shown in FIG. 17 includes a reticle positioning optical system (not shown) and a wafer positioning optical system (off-axis positioning optical system, TTL positioning optical system, and TTR positioning optical system).

The illumination optical system 222 of the apparatus shown in FIG. 17 is configured so as to be able to switch between small coherent illumination and small coherent illumination with small σ. Supplies the illumination light of (1a) or (1b) shown above to one of the aforementioned Levenson-type phase shift reticles, edge shifter-type reticles, or one of the periodic pattern reticles having no phase shifter,
Block 230 for large σ partial coherent illumination
The illumination light shown in (2) is supplied to a desired reticle. Switching from the large σ partial coherent illumination to the small σ partial coherent illumination is performed by changing the aperture stop provided immediately after the fly-eye lens of the optical system 222 to a coherent illumination having an aperture diameter sufficiently smaller than this aperture stop. What is necessary is just to replace it with an illumination diaphragm. Further, exposure can be performed by the method of this embodiment using an X-ray exposure apparatus having a configuration as shown in FIG.

[0082]

As described above, according to the present invention, multiple exposures including exposure of a first pattern having a periodic pattern and exposure of a second pattern having fine lines are performed on a substrate to be exposed. A mask having the same ratio between the line width of the first pattern and the interval between the line widths, so that the optimum exposure amount between the patterns is matched and the line width change with respect to the exposure amount is reduced. It is possible to realize a mask for performing multiple exposure that can be aligned and to obtain a wide exposure amount range common to patterns, an exposure method using the mask, an exposure apparatus, and a device manufacturing method.

[Brief description of the drawings]

FIG. 1 is a diagram showing a pattern arrangement of double exposure (in the case of a positive resist).

FIG. 2 is a diagram for explaining a problem when a pattern is created using a negative resist.

FIG. 3 is a diagram for explaining a problem when a pattern is formed using a positive resist.

FIG. 4 is a view showing a relationship between an exposure amount and a line width of the A section in FIGS. 2 and 3;

FIG. 5 is a diagram showing an example of an optimal pattern arrangement in which the ratio between the line width and the interval is equal regardless of the pitch.

FIG. 6 is a flowchart of double exposure.

FIG. 7 is a diagram illustrating the creation of a pattern according to the first embodiment of the present invention.

FIG. 8 is a diagram illustrating a relationship between an exposure amount and a line width according to the first embodiment of the present invention.

FIG. 9 is a diagram illustrating the creation of a pattern according to the second embodiment of the present invention.

FIG. 10 shows a relationship between an exposure amount and a line width in Example 2.

FIG. 11 is a diagram illustrating the creation of a pattern according to a third embodiment of the present invention.

FIG. 12 is a diagram illustrating the creation of a pattern according to a fourth embodiment of the present invention.

FIG. 13 is a diagram illustrating the creation of a pattern according to a fifth embodiment of the present invention.

FIG. 14 is a diagram illustrating the creation of a pattern according to a fifth embodiment of the present invention.

FIG. 15 is a diagram illustrating the creation of a pattern according to a sixth embodiment of the present invention.

FIG. 16 is a diagram illustrating the creation of a pattern according to a seventh embodiment of the present invention.

FIG. 17 is a schematic view of a high-resolution exposure apparatus that performs double exposure.

FIG. 18 is a view for explaining the principle of double exposure.

FIG. 19 is a view for explaining the principle of double exposure.

FIG. 20 is a schematic view of a conventional projection exposure apparatus.

FIG. 21 is a schematic view of an X-ray exposure apparatus.

[Explanation of symbols]

 191: Light source for far ultraviolet exposure 192: Illumination optical system 193: Illumination light 194: Mask 195: Object side exposure light 196: Optical system 197: Image side exposure light 198: Substrate 199: Substrate stage 221: KrF or ArF excimer laser 222 : Illumination optical system 223: mask 224: mask stage 225: mask changer 227: photographing optical system 228: wafer 229: stage 230: block

Claims (16)

[Claims] 1. A multiple exposure including exposure of a first pattern having a periodic pattern on a substrate to be exposed and exposure of a second pattern having a plurality of fine lines having the same line width and different intervals between the line widths. Wherein the first pattern has a plurality of periodic patterns in which the ratio between the line width overlapping with one of the fine line groups and the interval between the line widths is equal to each other. A mask characterized by the above-mentioned. 2. The mask according to claim 1, wherein the line widths of the plurality of periodic patterns of the first pattern are equal to each other. 3. The mask according to claim 1, wherein the first pattern having the periodic pattern has a plurality of pattern blocks. 4. The mask according to claim 1, wherein the second pattern having the fine lines is a pattern similar or similar to a design pattern. 5. The method according to claim 1, wherein the second pattern having the fine lines has a plurality of line widths.
The mask according to any one of the above items. 6. The mask according to claim 1, wherein the second pattern having the fine lines is formed by a pattern in which patterns having different line widths are separated from each other. . 7. The mask according to claim 1, wherein the second pattern having the fine lines is a pattern in which directions of the fine lines are mixed. 8. The mask according to claim 1, wherein the second pattern having the fine lines has an L-shaped pattern in which the directions of the fine lines are perpendicular to each other. 9. The mask according to claim 1, wherein the second pattern having the fine line has a pattern in which the direction of the fine line is oblique. 10. An exposure method using the mask according to claim 1 and exposing and transferring the mask pattern onto a photosensitive substrate. 11. The exposure according to claim 1, wherein the exposure with the first pattern is a pattern exposure with a certain image contrast, and the exposure with the second pattern is a pattern exposure with a lower image contrast than the first pattern. Claim 10
Exposure method according to 1. 12. The pitch P of the periodic pattern of the mask, the wavelength of the exposure light is λ, and the numerical aperture of the projection optical system used when exposing and transferring the mask pattern onto a photosensitive substrate is N.
The exposure method according to claim 10, wherein when A is set and k1 = P / (λ / NA), a relationship of 0.5 ≦ k1 ≦ 1.0 is satisfied. 13. An exposure apparatus having a multiple exposure mode using the mask according to claim 1 and projecting a pattern of the mask onto a photosensitive substrate by a projection optical system. 14. An exposure apparatus according to claim 1, wherein said first pattern is exposed as a pattern exposure having a certain image contrast, and said second pattern is exposed as a pattern exposure having a lower image contrast than said first pattern. The exposure apparatus according to claim 13, wherein: 15. A pitch P of a periodic pattern of the mask, a wavelength of exposure light λ, a numerical aperture of a projection optical system used for exposing and transferring the mask pattern onto a photosensitive substrate, and k1 = P The exposure apparatus according to claim 13, wherein, when // (λ / NA), 0.5 ≦ k1 ≦ 1.0 is satisfied. 16. A pattern on a reticle surface is transferred onto a wafer surface by the exposure method according to any one of claims 10 to 12 or the exposure apparatus according to any one of claims 13 to 15. Forming a device on the wafer through a developing process.