JP2001244191A - 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 reproducing lines of all widths through cyclic patterns of lines of the same width in a multi-exposure process, in which a first pattern comprising cyclic patterns and a second pattern are subjected to exposure operation, even if the second pattern comprises pattern different from each other in line width, an exposure method by the use of the same, an aligner and device manufacturing method. SOLUTION: A first pattern comprising cyclic patterns and a second pattern on a substrate as an object of exposure are subjected to an exposure operation in a multiple exposure process, where the cyclic patterns are composed of lines which are of the same width and arranged at the same line pitch with the second pattern, and the line width of the cyclic patterns is set, so as to be optimal in exposure with respect to the line widths of the second pattern.

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. These include, for example, semiconductor chips such as ICs and LSIs, display devices such as liquid crystal panels, detection devices such as magnetic heads, various devices such as imaging devices such as CCDs, and wide-area patterns used in micromechanics. Used in the manufacture of

[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. 16 is a schematic diagram of a conventional projection exposure apparatus. In FIG. 16, 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.

According to the patent (reference number 3701003), an exposure method and an exposure apparatus for performing double exposure of a periodic pattern exposure and a normal exposure on a substrate to be exposed (photosensitive substrate) without reducing the exposure wavelength without shortening the exposure wavelength. This indicates that it is possible to create a circuit pattern having a portion of 15 μm or less.

Here, the principle of the double exposure will be described in detail. 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 for normal exposure is
Each of the small areas in the exposure pattern area (exposure area) has a different exposure amount distribution, and each exposure amount may be equal to or greater than or equal to the exposure threshold. All the exposure amounts mentioned here indicate the exposure amounts on the resist.

FIG. 15 (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. 14 shows an exposure amount distribution at each exposure stage. Numerical values shown in the diagram of FIG. 14 represent exposure amounts on the resist. In FIG. 14, FIG.
4 (1) is an exposure amount distribution by a periodic exposure pattern in which a repetitive pattern occurs only in one-dimensional direction. The exposure amount other than the pattern is zero, and the pattern part is 1. FIG. 14B 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 carried out by double exposure without a development step, a distribution of the sum of the respective exposure amounts is formed 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. 14C 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. 15 shows a pattern and a mask for forming the exposure dose distribution shown in FIG. FIG.
Reference numeral 5 (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 this exposure pattern forms the exposure dose distribution shown in FIG. 14A by a line and space pattern having a line width of 0.1 μm for each line and space. 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 in which the gate pattern shown in FIG.

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. 15B are exposed, a multi-level exposure distribution shown in FIG. 14B is formed. In this example, the pattern to be formed is shown with 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 exposure which has a lower resolution than that of the periodic pattern exposure, but is capable of exposing in an arbitrary pattern. As a typical example, the pattern of a mask is projected by a projection optical system. Projection exposure capable of projecting is used. The pattern exposed by the normal exposure includes a fine pattern having a resolution equal to or less than the resolution (hereinafter, referred to as a normal exposure pattern), and the periodic pattern exposure forms a periodic pattern having the same line width as the fine pattern. For this periodic pattern exposure, a Levenson-type phase shift mask or the like is used. One example is shown in FIG.
It was shown to. By exposing the periodic pattern of FIG. 1 and the normal exposure pattern of FIG. 1 at the same position, it becomes possible to obtain a fine pattern FIG.

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.

[0021]

As described above, in order to improve the resolution of the normal exposure pattern shown in FIG. 1, the high-resolution periodic pattern shown in FIG. 1 is exposed at the same position.

In this case, a fine line that cannot be obtained by exposure using only the normal exposure pattern shown in FIG. 1 can be created by combining it with a high-resolution periodic pattern. As described above, when the fine line of the normal exposure pattern has one line width, the line width of the high resolution periodic pattern may be made to match the line width of the fine line.

However, when the fine lines of the normal exposure pattern are composed of a plurality of line widths, the composite image changes depending on which line width of the high-resolution periodic pattern is used.

For example, in a case where a pattern is formed by a light shielding portion as shown in FIG. 2 and a pattern in which two line widths are mixed as a normal exposure pattern, one of two types of line widths is used. It is conceivable to use a periodic pattern that matches the crab. The normal exposure pattern shown in FIG.
A pattern having a large line width in one space S1 and a pattern having a small line width in a line width L2 space S2 are mixed, but the pitch is equal.

In this example, since the pattern is formed by the light shielding portion, the space portion (Cr) of the periodic pattern and the pattern portion (Cr) of the normal exposure pattern overlap.
Thus, a composite image as shown in FIG.

When the periodic pattern is determined by focusing on the thin line width L2 of the normal exposure pattern as shown in 1) of FIG. 2, the line width L which is the light transmitting portion as shown in 1) of FIG.
1. It is conceivable to use a high-resolution periodic pattern of the space S1 which is a light shielding portion. In such a case, the thin pattern L2 that matches the line width of the periodic pattern can be reproduced well, but the thick pattern L1 that does not match the line width of the periodic pattern becomes smaller than the desired pattern. A good image is not always obtained with a pattern having two line widths.

Similarly, when the periodic pattern is determined by paying attention to the thick line width L1 of the normal exposure pattern as shown in 2) of FIG. 2, the light transmission portion as shown in 2) of FIG. 2 is obtained. It is conceivable to use a high-resolution periodic pattern having a line width L2 and a space S2 which is a light shielding portion. In such a case, the thick pattern L1 that matches the line width of the periodic pattern can be reproduced well, but the thin pattern L2 that does not match the line width of the periodic pattern becomes smaller than the desired pattern. A good image is not always obtained with a pattern having two line widths.

This is because two patterns having different line widths are:
In the first place, since the optimum exposure amount is different, if a periodic pattern optimized for either is used, only a pattern having an optimized line width can be reproduced well.

In view of the above, the present invention has been made to solve the above problems, and in a multiple exposure including an exposure of a first pattern having a periodic pattern and an exposure of a second pattern, the second pattern is formed of a plurality of line widths. Even if it contains
By a periodic pattern composed of different types of line widths, a mask for performing multiple exposures that enable good reproduction of all line widths, an exposure method using the mask, an exposure apparatus,
And a device manufacturing method.

[0030]

In order to achieve the above object, the present invention provides a mask for performing multiple exposures as described in the following (1) to (13), an exposure method using the mask, and an exposure method. An apparatus and a device manufacturing method are provided. (1) A mask of the first pattern for performing multiple exposure including exposure of a first pattern having a periodic pattern and exposure of a second pattern having a plurality of different line widths on a substrate to be exposed, The periodic pattern is formed of one type of line width, and the one type of line width is set so that an exposure amount in multiple exposure with each line width of the second pattern is optimized. Mask to do. (2) The line width of the periodic pattern is equal to an average value of a plurality of different line widths constituting the second pattern, or has a line width obtained by adding a bias to the average value. The mask according to the above (1). (3) The mask according to (2), wherein the bias has a bias amount of ± P / 4. (4) The line width of the periodic pattern is equal to the average value of the line widths of the plurality of light shielding portions constituting the second pattern, or has a line width obtained by adding a bias to the average value. The mask according to the above (2) or (3), wherein: (5) The mask according to (4), wherein the light-shielding portion is a light-shielding portion of Cr. (6) The line width of the periodic pattern is equal to the average value of the line widths of the plurality of light transmission portions constituting the second pattern, or a line width obtained by applying a bias to the average value. The mask according to the above (2) or (3), comprising: (7) The line width of the light-shielding portion or the light-transmitting portion of the periodic pattern is selected from among a plurality of line widths of the second pattern.
The mask according to any one of the above (4) to (6), wherein the mask has an average value of a line width coinciding with the direction of the periodic pattern. (8) The line width of the light-shielding portion or the light-transmitting portion of the periodic pattern is selected from among a plurality of line widths of the second pattern.
The mask according to any one of the above (4) to (6), wherein when the resolution is 2L, the resolution is equal to the average value of the line width of 2L or less or a value obtained by adding a bias to the average value. (9) The line width of the periodic pattern is equal to the average value of the line width of the second pattern for each of the areas of the second pattern divided into several types of areas having different line widths, or The mask according to any one of the above (2) to (8), wherein the mask has a line width obtained by adding a bias to the average value. (10) The mask according to any one of the above (1) to (9), wherein the pattern 1 is constituted by a phase shift mask, a mask created by two-beam interference, or the like. (11) An exposure method using the mask according to any one of (1) to (10), and exposing and transferring the mask pattern onto a photosensitive substrate. (12) An exposure apparatus having a multiple exposure mode in which the mask according to any one of (1) to (10) is used and a pattern of the mask is projected onto a photosensitive substrate by a projection optical system. (13) After the pattern on the reticle surface is transferred onto the wafer surface by the exposure method according to (11) or the exposure apparatus according to (12), the device is transferred to the wafer through a developing process. A device manufacturing method characterized by manufacturing.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In an embodiment of the present invention,
By using the above configuration, when performing the double exposure of the periodic pattern and the normal exposure pattern, even when the normal exposure pattern is a pattern composed of a plurality of line widths and has the same pitch, the normal exposure pattern is configured with one type of line width. By using the periodic pattern, it is possible to reproduce all line widths satisfactorily. Here, the pitch of the periodic pattern is equal to the pitch of the normal exposure pattern.
For example, as shown in FIG. 3, when a pattern having the same pitch P composed of two types of line widths L1 and L2 is used as a normal exposure pattern, the line width of the periodic pattern is two types of line widths L1 and L2. By using the average value or a value obtained by adding a bias to the average value, a good composite image can be obtained.

Since FIG. 3 shows a case where a pattern is formed in the light-shielding portion, the line width of the light-shielding portion of the periodic pattern is equal to the average value of the two types of line widths L1 and L2 of the normal exposure pattern. A pattern will be used. Here, since the pitch P of the periodic pattern is made equal to the pitch of the normal exposure pattern, the line width of the light transmitting portion is automatically determined from the pitch P and the line width of the light shielding portion.

Originally, the optimum exposure amount differs due to the difference in line width. However, by performing double exposure of a periodic pattern composed of one type of line width and a normal exposure pattern, two types of exposure are performed. Is adjusted, and as a result, both patterns with two line widths can be reproduced well. That is, in the exposure method of performing the double exposure of the normal exposure pattern and the periodic pattern, when a pattern composed of a plurality of line widths and having the same pitch is used as the normal exposure pattern, the pitch composed of one type of line width is By using the same periodic pattern, it is possible to reproduce all the line widths well. And this one kind of line width is
It is characterized by an average value of the line widths constituting the normal exposure pattern or a value obtained by adding a bias to the average value.

The periodic pattern used here has a phase of 0 and 1
A phase shift mask that is inverted by 80 degrees may be used, or a similar effect can be obtained by using two-beam interference.
Further, in the case of FIG. 3, since the normal exposure pattern is in the same direction as the periodic pattern, the line width of the periodic pattern may be based on the average value of the two types of line widths constituting the normal exposure pattern. As described above, there is no particular problem if the direction of the periodic pattern and the normal exposure pattern are the same, but even if there is a pattern having a direction different from the periodic pattern in the normal exposure pattern, when determining the line width of the periodic pattern, Attention is paid only to the line width in the same direction as the period in the normal exposure pattern, and the average value thereof is used as a reference. Even in the same direction as the period, if the line width is large and the line width accuracy does not matter, the line width of the periodic pattern may be set based on the average value of fine lines with strict line width accuracy.

[0035]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below. Before understanding these embodiments, a flowchart of the double exposure method is shown in FIG. Keep it. FIG. 4 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. When a step is included, it is of course possible to perform the steps alternately. Note that a step of performing precise alignment is performed between each exposure step, but details regarding this processing are omitted.

Each of the embodiments described below has a wavelength of 248n.
This is a device in which a periodic pattern is devised when performing double exposure of periodic pattern exposure and normal pattern exposure using a krF excimer stepper of m. In addition, the present invention is not limited to each embodiment described below at all,
Various changes can be made without departing from the spirit of the present invention.

[Embodiment 1] This embodiment 1 relates to a case where a pattern is formed by a light shielding portion, and a pattern composed of two types of line widths L1 and L2 having the same pitch is used as a normal exposure pattern. The case will be described with reference to FIG.

FIG. 5 shows, as a composite pattern, a periodic pattern that is actually used, a normal exposure pattern, and a positional relationship in which they are double-exposed. The purpose of combining these two patterns is to finally obtain a pattern having the same shape as the normal exposure pattern in FIG. The normal exposure pattern shown in FIG. 5 includes two types of line widths L1 and L2, and the pitches of the two are equal. In order to satisfactorily reproduce all the patterns having the same pitch constituted by the two types of line widths L1 and L2, the periodic pattern constituted by one type of line width shown in FIG. 5 is used. .

In the first embodiment, since the pattern is created by the light-shielding portion, the line width of the light-shielding portion of the periodic pattern is set to two types of line widths L1 and L that constitute the normal exposure pattern.
Equal to the average of 2. Here, since the pitch of the periodic pattern is equal to the pitch of the normal exposure pattern, the line width of the light transmitting portion of the periodic pattern is determined by the difference between the pitch and the light shielding portion. The relationship is shown in the following equation. Line width of light shielding part of periodic pattern = (L1 + L2) / 2 Line width of light transmitting part of periodic pattern = P− (L1 + L2) /
2 Pitch of periodic pattern = P Originally, when the line width is different, the optimal exposure amount is different.
By performing double exposure using a periodic pattern composed of one type of line width as described above, the exposure amount of two types of line widths can be adjusted, and as a result, two types of line widths can be adjusted. The pattern can be reproduced well. As described above, when the pattern is formed by the light shielding portion, and when the normal exposure pattern is a pattern composed of two types of line widths and has the same pitch, the line width of the light shielding portion of the periodic pattern is equal to that of the normal exposure pattern. By using a periodic pattern which is an average value of two types of line widths and whose pitch is equal to the pitch of the normal exposure pattern, a good composite image can be obtained. Here, the line width of the light shielding portion of the periodic pattern is the average value of the two types of line width of the normal exposure pattern.
The optimum value may be slightly shifted from the average value depending on the exposure amount ratio when the periodic pattern and the normal exposure pattern are combined. However, even in this case, the bias amount centered on the average value is within ± P / 4, and it is known that other than that is not preferable.

[Embodiment 2] This embodiment 2 is a case where a normal exposure pattern composed of two types of line widths L1 and L2 and having the same pitch is used, as in the case of the embodiment 1. A case of creating a pattern will be described with reference to FIG.

FIG. 6 shows, as a composite pattern, the periodic pattern and the normal exposure pattern that are actually used, and the positional relationship of double exposure of them. The purpose is to finally obtain a pattern having the same shape as the normal exposure pattern in FIG. 6 by combining these two patterns. The normal exposure pattern shown in FIG. 6 includes two types of line widths L1 and L2, and the pitches of the two are equal.

In order to satisfactorily reproduce all of the patterns having the same pitch composed of the two types of line widths L1 and L2, it is necessary to use a cycle composed of one type of line width shown in FIG. Use a pattern.

In the second embodiment, since the pattern is formed by the light transmitting portion, the line width of the light transmitting portion of the periodic pattern is changed to two types of line widths L1 and L which constitute the normal exposure pattern.
Equal to the average of 2. Here, since the pitch of the periodic pattern is equal to the pitch of the normal exposure pattern, the line width of the light shielding portion of the periodic pattern is determined by the difference between the pitch and the light transmitting portion. The relationship is shown in the following equation. Line width of light transmitting portion of periodic pattern = (L1 + L2) / 2 Line width of light shielding portion of periodic pattern = P− (L1 + L2) /
2 Pitch of periodic pattern = P Originally, when the line width is different, the optimal exposure amount is different.
By performing double exposure using a periodic pattern composed of one type of line width as described above, the exposure amount of two types of line widths can be adjusted, and as a result, two types of line widths can be adjusted. The pattern can be reproduced well. As described above, in the case where the pattern is formed by the light transmitting portion, the line width of the light transmitting portion is equal to the two types of the normal exposure pattern when the normal exposure pattern is a pattern composed of two types of line widths and has the same pitch. By using a periodic pattern, which is the average value of the line width and the pitch is equal to the pitch of the normal exposure pattern, a good composite image can be obtained.
Here, the line width of the light transmission portion of the periodic pattern is the average value of the two types of line widths of the normal exposure pattern, but the optimum value is the average value depending on the exposure ratio when combining the periodic pattern and the normal exposure pattern. May shift slightly from value.
However, even in this case, the bias amount is ± P around the average value.
It is within / 4, and it is known that other than that is not preferable.

[Embodiment 3] The present embodiment 3 relates to a case where a pattern is formed in the light shielding portion, and the normal exposure pattern is 3
A case where the line widths are configured with different line widths and the line width accuracy is severe for all three types of line widths will be described with reference to FIG.

FIG. 7 shows an actually used periodic pattern and a normal exposure pattern. The purpose is to finally obtain a pattern having the same shape as the normal exposure pattern of FIG. 7 by combining these two patterns. The normal exposure pattern shown in FIG. 7 has three types of line widths L1, L2, and L3, and all have the same pitch. Such three types of line widths L1 and L
In order to satisfactorily reproduce all of the patterns having the same pitch composed of L2 and L3, a periodic pattern composed of one type of line width shown in FIG. 7 is used.

In the third embodiment, since the pattern is formed by the light-shielding portion, the line width of the light-shielding portion of the periodic pattern is changed to three types of line widths L1 and L constituting the normal exposure pattern.
2. Make it equal to the average value of L3. Here, since the pitch of the periodic pattern is equal to the pitch of the normal exposure pattern, the line width of the light transmitting portion of the periodic pattern is determined by the difference between the pitch and the light shielding portion. The relationship is shown in the following equation. Line width of light shielding part of periodic pattern = (L1 + L2 + L3)
/ 3 Line width of light transmitting portion of periodic pattern = P− (L1 + L2 + L
3) / 3 Pitch of periodic pattern = P Originally, when the line width is different, the optimum exposure amount is different.
By performing double exposure using a periodic pattern composed of one type of line width as described above, the exposure amount of three types of line widths can be adjusted, and as a result, two types of line widths can be adjusted. The pattern can be reproduced well. As described above, in the case where the pattern is formed by the light-shielding portion, and when the normal exposure pattern is a pattern composed of three types of line widths and has the same pitch, the line width of the light-shielding portion of the periodic pattern is An excellent composite image can be obtained by using a periodic pattern which is an average value of three types of line widths and whose pitch is equal to the pitch of the normal exposure pattern. Here, the line width of the light shielding portion of the periodic pattern is the average value of the two types of line width of the normal exposure pattern.
The optimum value may be slightly shifted from the average value depending on the exposure amount ratio when the periodic pattern and the normal exposure pattern are combined. However, even in this case, the bias amount centered on the average value is within ± P / 4, and it is known that other than that is not preferable. When combined with Example 1, it can be seen that the same effect can be obtained if the pitch is equal, regardless of whether the normal exposure pattern has a plurality of line widths, and whether the patterns are in contact with or apart from each other.

In this embodiment, when the line width accuracy of L1 and L2 is strict and the line width accuracy is not a problem because L3 is thick, the line width of the periodic pattern is determined by the line width accuracy of L1 and L2 which are strict. May be created. In this case, the above equation is as follows. Line width of light shielding part of periodic pattern = (L1 + L2) / 2 Line width of light transmitting part of periodic pattern = P− (L1 + L2) /
2 Pitch of periodic pattern = P [Embodiment 4] This embodiment 4 is a case where a pattern is created by a light shielding portion, and a normal exposure pattern is composed of two types of line widths, and different directions are mixed. This case will be described with reference to FIG.

FIG. 8 shows an actually used periodic pattern and a normal exposure pattern. By combining these two patterns, finally, FIG.
The purpose is to obtain a pattern having the same shape as the normal exposure pattern. The normal exposure pattern shown in FIG. 8 has two types of line widths L1 and L2 in different directions, and the pitches of the two are equal.

In order to satisfactorily reproduce all of the patterns having the same pitch composed of the two types of line widths L1 and L2, it is necessary to use a cycle composed of one type of line width shown in FIG. Use a pattern.

In the fourth embodiment, since the pattern is formed by the light-shielding portion, the line width of the light-shielding portion of the periodic pattern is changed to the two types of line widths L1 and L that constitute the normal exposure pattern.
Equal to the average of 2. Here, since the pitch of the periodic pattern is equal to the pitch of the normal exposure pattern, the line width of the light transmitting portion of the periodic pattern is determined by the difference between the pitch and the light shielding portion. The relationship is shown in the following equation. Line width of light shielding part of periodic pattern = (L1 + L2) / 2 Line width of light transmitting part of periodic pattern = P− (L1 + L2) /
2 Pitch of periodic pattern = P Originally, when the line width is different, the optimal exposure amount is different.
By performing double exposure using a periodic pattern composed of one type of line width as described above, the exposure amount of two types of line widths can be adjusted, and as a result, two types of line widths can be adjusted. The pattern can be reproduced well. As described above, in the case where the pattern is formed by the light shielding portion, even when the normal exposure pattern is a pattern composed of two types of line widths and has the same pitch and a pattern in which directions are mixed, the light of the periodic pattern can be obtained. The line width of the light-shielding portion is the average value of the two types of line widths of the normal exposure pattern, and a good synthesized image can be obtained by using a periodic pattern whose pitch is equal to the pitch of the normal exposure pattern.
Here, the line width of the light-shielding portion of the periodic pattern is an average value of two types of line widths of the normal exposure pattern, but the optimum value is an average value depending on an exposure amount ratio when the periodic pattern and the normal exposure pattern are combined. May shift slightly from value.
However, even in this case, the bias amount is ± P around the average value.
It is within / 4, and it is known that other than that is not preferable. The normal exposure pattern of this embodiment has different line widths in the vertical direction and the horizontal direction, but since each direction is configured with the same line width, the individual exposure pattern is adjusted to the line width in each direction. Although it is better, it is easier to use a periodic pattern that is entirely formed with the same line width. It is also possible to adjust the exposure amount of two line width patterns in which the optimal exposure amount is shifted, In both cases, an optimal composite image can be obtained. Further, if this method is used, the same idea can be obtained even when a plurality of line widths having different periodic directions are mixed.

[Embodiment 5] The present embodiment 5 relates to a case where a pattern is formed in a light shielding portion.
The case of an L-shaped pattern composed of different line widths will be described with reference to FIG. FIG. 9 shows a periodic pattern and a normal exposure pattern actually used.
The purpose is to finally obtain a pattern having the same shape as the normal exposure pattern of FIG. 9 by combining these two patterns. The normal exposure pattern shown in FIG. 9 is L-shaped with two types of line widths L1 and L2, and the pitches of both are equal.

In order to satisfactorily reproduce such an L-shaped pattern having the same pitch composed of two kinds of line widths L1 and L2, it is necessary to use a cycle composed of one kind of line width shown in FIG. Use a pattern.

In this embodiment, since the pattern is formed by the light shielding part, the line width of the light shielding part of the periodic pattern is
The average value is equal to the average value of the two types of line widths L1 and L2 constituting the normal exposure pattern. Here, since the pitch of the periodic pattern is equal to the pitch of the normal exposure pattern, the line width of the light transmitting portion of the periodic pattern is determined by the difference between the pitch and the light shielding portion. The relationship is shown in the following equation. Line width of light shielding part of periodic pattern = (L1 + L2) / 2 Line width of light transmitting part of periodic pattern = P− (L1 + L2) /
2 Pitch of periodic pattern = P Originally, when the line width is different, the optimal exposure amount is different.
By performing double exposure using a periodic pattern composed of one type of line width as described above, the exposure amount of two types of line widths can be adjusted, and as a result, two types of line widths can be adjusted. The pattern can be reproduced well. As described above, when the pattern is formed by the light shielding portion, and when the normal exposure pattern is a pattern composed of two types of line widths and has the same pitch, the line width of the light shielding portion of the periodic pattern is equal to that of the normal exposure pattern. By using a periodic pattern which is an average value of two types of line widths and whose pitch is equal to the pitch of the normal exposure pattern, a good composite image can be obtained.

As shown in FIG. 10, the same effect can be obtained not only in the L / S pattern but also when a contact hole is connected.

[Embodiment 6] This embodiment 6 relates to a case where a pattern is formed in a light shielding portion.
With reference to FIG. 11, a description will be given of a case in which the patterns are configured with different types of line widths and are connected diagonally.

FIG. 11 shows an actually used periodic pattern and a normal exposure pattern. By combining these two patterns, finally, FIG.
The purpose is to obtain a pattern having the same shape as the normal exposure pattern. The normal exposure pattern shown in FIG. 11 has two types of line widths L1 and L2, and the pitches of both are equal. Since this normal exposure pattern includes fine lines of lower resolution, the light intensity distribution on the wafer is
Multivalued.

In order to satisfactorily reproduce all of the patterns having the same pitch constituted by the two types of line widths L1 and L2, it is necessary to use a cycle constituted by one type of line width shown in FIG. Use a pattern.

In this embodiment, since the pattern is formed by the light-shielding portion, the line width of the light-shielding portion of the periodic pattern is
The average value is equal to the average value of the two types of line widths L1 and L2 constituting the normal exposure pattern. Here, since the pitch of the periodic pattern is equal to the pitch of the normal exposure pattern, the line width of the light transmitting portion of the periodic pattern is determined by the difference between the pitch and the light shielding portion. The relationship is shown in the following equation. Line width of light shielding part of periodic pattern = (L1 + L2) / 2 Line width of light transmitting part of periodic pattern = P− (L1 + L2) /
2 Pitch of periodic pattern = P Originally, when the line width is different, the optimal exposure amount is different.
By performing double exposure using a periodic pattern composed of one type of line width as described above, the exposure amount of two types of line widths can be adjusted, and as a result, two types of line widths can be adjusted. The pattern can be reproduced well.

As described above, when the pattern is formed by the light-shielding portion and the normal exposure pattern is a pattern composed of two types of line widths and has the same pitch, the line width of the light-shielding portion of the periodic pattern is usually By using a periodic pattern that is the average value of two types of line widths of the exposure pattern and whose pitch is equal to the pitch of the normal exposure pattern, a good composite image can be obtained. Here, the line width of the light-shielding portion of the periodic pattern indicates the average value of the two types of line widths of the normal exposure pattern. However, the optimum value may vary depending on the exposure ratio when the periodic pattern and the normal exposure pattern are combined. There may be a slight shift from the average. However, even in this case, the bias amount centered on the average value is within ± P / 4, and it is known that other than that is not preferable.

[Embodiment 7] The present embodiment 7 relates to a case where a pattern is formed by a light shielding portion, in which there are a plurality of patterns having the same pitch on the same mask as a normal exposure pattern. The case where the area is divided into different types will be described with reference to FIG.

FIG. 12 shows an actually used periodic pattern and a normal exposure pattern. By combining these two patterns, finally, FIG.
The purpose is to obtain a pattern having the same shape as the normal exposure pattern. The normal exposure pattern shown in FIG. 12 is on the same mask and all have the same pitch but are largely divided into four types of areas A, B, C, and D. The pattern existing in each area has two types of line widths. It is composed of Since the normal exposure pattern includes fine lines of a resolution or less, the light intensity distribution on the wafer has multiple values.

In order to satisfactorily reproduce the pattern having such a configuration, a periodic pattern composed of one kind of line width optimized for each area shown in FIG. 12 is used. This is the case when the line width of the pattern may be different. Here, since the area is divided into four areas of A, B, C, and D, a different periodic pattern is used for each area, which is optimized in consideration of each normal exposure pattern.

In the present embodiment, since the pattern is formed by the light-shielding portion, the line width of the light-shielding portion of the periodic pattern is determined for each area by the average value of the two types of line widths constituting the normal exposure pattern. Equal to Here, since the pitch of the periodic pattern is equal to the pitch of the normal exposure pattern, the line width of the light transmitting portion of the periodic pattern is determined by the difference between the pitch and the light shielding portion. A, D: Line width of light shielding portion of periodic pattern = (L1 + L2) / 2 Line width of light transmitting portion of periodic pattern = P− (L1 + L2) / 2 Pitch of periodic pattern = P B: Light shielding portion of periodic pattern Line width of (L3 + L4) / 2 Line width of light transmitting portion of periodic pattern = P− (L3 + L4) / 2 Pitch of periodic pattern = PC: Line width of light shielding portion of periodic pattern = (L5 + L6) / 2 period Line width of light transmitting portion of pattern = P− (L5 + L6) / 2 Pitch of periodic pattern = P Originally, when the line width is different, the optimum exposure amount is different.
As described above, by performing double exposure using a periodic pattern composed of one type of line width for each area, it is possible to adjust the amount of exposure for two types of line widths. The pattern with the line width can be reproduced well.

As described above, in the case where a pattern is formed by the light shielding portion, there are a plurality of patterns having the same pitch on the same mask where the normal exposure pattern is formed, and each pattern is divided into several areas. In this case, since the optimal periodic pattern is used for each area, the line width of the light shielding portion of the periodic pattern for each area is the average value of the two types of line widths of the normal exposure pattern, and the pitch is the normal exposure pattern. By using a periodic pattern equal to the pattern pitch, a good composite image can be obtained.

Of course, as described in the embodiments other than the present embodiment, instead of using different periodic patterns optimized for each area on the same mask, the following is shown in consideration of all normal exposure patterns. Of course, it is also possible to use a periodic pattern constituted by the line width of one kind of light shielding portion. Line width of light shielding part of periodic pattern = (L1 + L2 + L3 +
L4 + L5 + L6) / 6 Line width of light transmitting portion of periodic pattern = P− (L1 + L2 +
L3 + L4 + L5 + L6) / 6 Pitch of Periodic Pattern = P In summary, in the exposure method of performing double exposure of the normal exposure pattern and the periodic pattern, a pattern composed of a plurality of line widths and having the same pitch is used as the normal exposure pattern. In this case, it is possible to reproduce all the line widths satisfactorily by using a periodic pattern composed of one kind of line width and having the same pitch. And
This one type of line width is characterized by being the average value of the line widths constituting the normal exposure pattern. And
Even if the normal exposure pattern is composed of multiple line widths, even if patterns with different line widths are separated from each other on the same mask, The effect of the present invention can be obtained as long as the patterns are formed in the same pattern.

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. 13, 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.

In FIG. 13, reference numeral 229 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. 13 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. 13 is configured to be capable of switching between small coherent illumination with small σ and partial coherent illumination with large σ. In the case of partial coherent illumination with small σ, The illumination light of the above-described (1a) or (1b) shown in the block 230 is supplied to one of the above-mentioned Levenson-type phase shift reticles, edge shifter-type reticles, or periodic pattern reticles having no phase shifter. In the case of partial coherent illumination of σ, the illumination light of (2) shown in block 230 is supplied to a desired reticle. Switching from large σ partially coherent illumination to small σ partially coherent illumination is:
The aperture stop provided immediately after the fly-eye lens of the normal optical system 222 may be replaced with a partial coherent illumination stop having an aperture diameter sufficiently smaller than the aperture stop.

Further, X having a configuration as shown in FIG.
It is also possible to perform exposure by the method of this embodiment using a line exposure apparatus. The present invention is not limited to the above-described embodiments and the like, and can be variously modified without departing from the gist of the present invention.

[0070]

According to the multiple exposure including the exposure of the first pattern having the periodic pattern and the exposure of the second pattern, the second exposure is performed.
Even if the pattern includes a pattern composed of a plurality of line widths, multiple exposure is performed so that all line widths can be satisfactorily reproduced by a periodic pattern composed of one type of line width. , An exposure method using the mask, an exposure apparatus, and a device manufacturing method can be realized.

[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 of a conventional example in double exposure.

FIG. 3 is a diagram for explaining a method for solving the problem of the conventional example.

FIG. 4 is a view showing a flowchart of double exposure.

FIG. 5 is a diagram illustrating the creation of a pattern according to the first embodiment of the present invention.

FIG. 6 is a diagram illustrating the creation of a pattern according to the second embodiment of the present invention.

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

FIG. 8 is a diagram illustrating the creation of a pattern according to a fourth embodiment of the present invention.

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

FIG. 10 is a diagram illustrating the creation of a pattern according to a fifth embodiment of the present invention.

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

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

FIG. 13 is a schematic diagram illustrating a configuration of a high-resolution exposure apparatus that performs double exposure.

FIG. 14 is a view for explaining the principle of double exposure.

FIG. 15 is a diagram for explaining the principle of double exposure.

FIG. 16 is a schematic diagram showing a configuration of a conventional projection exposure apparatus.

FIG. 17 is a schematic diagram showing a configuration 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 (13)

[Claims] 1. A first pattern mask for performing multiple exposure including exposure of a first pattern having a periodic pattern and exposure of a second pattern having a plurality of different line widths on a substrate to be exposed. The periodic pattern is configured with one type of line width, and the one type of line width is set so that the exposure amount in multiple exposure with each line width of the second pattern is optimized. The featured mask. 2. The method according to claim 1, wherein the line width of the periodic pattern is equal to an average value of a plurality of different line widths forming the second pattern, or has a line width obtained by adding a bias to the average value. The mask according to claim 1, wherein 3. The mask according to claim 2, wherein the bias has a bias amount of ± P / 4. 4. The line width of the periodic pattern is equal to an average value of the line widths of a plurality of light shielding portions constituting the second pattern, or a line width obtained by applying a bias to the average value. The mask according to claim 2, comprising: 5. The mask according to claim 4, wherein the light shielding portion is a Cr light shielding portion. 6. The line width of the periodic pattern is equal to an average value of the line widths of the plurality of light transmission portions constituting the second pattern, or a bias is applied to the average value. The mask according to claim 2 or 3, wherein the mask has a line width. 7. The line width of a light-shielding portion or a light transmitting portion of the periodic pattern is an average value of a line width of the plurality of line widths constituting the second pattern, the line width being coincident with the direction of the periodic pattern. The mask according to any one of claims 4 to 6, wherein the masks are equal. 8. A line width of a light-shielding portion or a light transmitting portion of the periodic pattern is an average value of line widths of 2L or less when a resolution is 2L among a plurality of line widths constituting the second pattern. 7. The mask according to claim 4, wherein the mask is equal to a value obtained by adding a bias to the average value. 8. 9. The line width of the periodic pattern is equal to the average value of the line width of the second pattern for each of the areas of the second pattern divided into several types of areas having different line widths. 9. The mask according to claim 2, wherein the mask has a line width obtained by adding a bias to the average value. 10. The pattern 1 is a phase shift mask,
Alternatively, it is constituted by a mask or the like created by two-beam interference.
The mask according to Item. 11. An exposure method using the mask according to claim 1, and exposing and transferring the mask pattern onto a photosensitive substrate. 12. An exposure apparatus using the mask according to claim 1 and having a multiple exposure mode for projecting a pattern of the mask onto a photosensitive substrate by a projection optical system. 13. After the pattern on the reticle surface is transferred onto the wafer surface by the exposure method according to claim 11, or the exposure apparatus according to claim 12, the device is transferred to the device through a development process. A device manufacturing method characterized by manufacturing.