JPH10133356A - Photomask and pattern forming method - Google Patents

Abstract

(57) Abstract: An object of the present invention is to suppress an error in dimensional accuracy due to a difference in pattern interval in pattern formation using a phase shift mask. SOLUTION: The phase of a transmission area on both sides of a light shielding area is 18
When forming a resist pattern using the phase shift mask 4 different by 0 degrees, when exposing the positive resist 1, the width of the light-shielding region 5A and the light-shielding region 5B of the mask 4 is changed according to the interval between adjacent patterns. In addition, a fine pattern having the same line width is formed with high dimensional accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to the formation of a fine pattern in a lithography process in the manufacture of a semiconductor integrated circuit.

[0002]

2. Description of the Related Art In recent years, the design rules for semiconductors have been steadily miniaturized, and semiconductor chips of the 0.25 μm level have already begun to appear on the market. With such a trend of miniaturization, the exposure wavelength in lithography has been shortened, and the wavelength has shifted from g-line (436 nm) to i-line (365 nm) to KrF excimer laser (248 nm). ArF excimer laser (193n)
Steppers using m) as exposure light have been developed, but their development has been delayed due to the problem that the lens material absorbs ultrashort wavelength light such as ArF excimer laser light. Therefore, various super-resolution techniques have been studied for the lithography technique using a KrF excimer laser.

In general, the limit resolution of photolithography by the reduced projection exposure method is proportional to the exposure wavelength and inversely proportional to the numerical aperture of the projection lens. Conventionally, formation of a pattern of about 0.3 μm has been achieved using a KrF excimer laser (wavelength 248 nm) and a projection lens having a numerical aperture of 0.4 to 0.5.

[0004] Among super-resolution techniques for improving the resolution limit in the reduced projection exposure method, one of the techniques showing excellent resolution is a method using a Levenson phase shift mask.
An example of pattern formation using a conventional Levenson phase shift mask will be described below.

FIGS. 8A to 8C are cross-sectional views showing the steps of a conventional pattern forming method using a phase shift mask. In these figures, 21 is a positive resist, 2
2 is a substrate, 23A and 23B are exposure light, and 24 is a phase shift mask. 25 is a light shielding area, 26A and 26
B is a transmission area, and transmission area 26B is transmission area 26A.
Is set so that the phase of the exposure light 23A differs by 180 degrees. The exposure light 23A illuminates the mask 24, and the exposure light 23B that has passed through the transmission area of the mask
Image.

In FIG. 8A, first, a positive resist 21 is applied on a substrate 22. The positive resist 21 is a chemically amplified resist for a KrF excimer laser and is applied with a thickness of 0.5 μm. Next, the positive resist 21 was exposed through the phase shift mask 24.

The exposure conditions of the exposure apparatus (stepper) are as follows: exposure wavelength λ = 248 nm, numerical aperture NA = 0.48, coherent factor σ = 0.30. As shown in FIG. 8B, the Levenson phase shift mask has a transmission region 26.
B quartz is dug, and the phase of the light passing therethrough is inverted by 180 degrees with respect to the light passing through the transmission region 26A.

First, the exposure light 23A illuminates the mask 24,
Light is diffracted according to the pattern density. In the case of the Levenson phase shift mask, since the phases of the transmission regions on both sides differ by 180 degrees via the light-shielding region, zero-order light and even-order light are canceled out in the periodic pattern. In addition, odd-order lights such as ± 1, 3, 5, etc. are normally diffracted at a half angle of the mask. Generally, the angle of light that can pass through the projection lens is finite,
The resolution of the pattern can be said to be the pattern period that can pass through the lens. Since a Levenson phase shift mask diffracts light at half the angle of a normal mask, ideally it is possible to obtain a high resolution twice that of a normal mask.

In order to realize high resolution by using a Levenson phase shift mask, it is necessary to align spatial light phases (to increase coherency). The NA of the projection lens and the NA of the illumination system as units representing the degree of coherency
(Coherent factor) is used. This σ
Is smaller, the coherency of light is higher. Generally, when a normal mask is illuminated by a stepper, the coherent factor of the optical system is approximately σ = 0.5 to 0.8, but when a Levenson phase shift mask is used, σ =
It needs to be about 0.2 to 0.4.

After the pattern exposure shown in FIG.
EB (Post Exposure Baking: post exposure baking) and development with a normal alkaline aqueous solution for 60 seconds to form a resist pattern (FIG. 8C). According to this pattern forming method, a 0.16 μm line and space pattern much finer than the exposure wavelength of 248 nm (0.248 μm) could be resolved.

[0011]

Generally, since the Levenson phase shift mask can obtain an effect with a fine periodic pattern, application to a DRAM device including many periodic patterns has been studied. However, the Levenson phase shift mask has a problem that, even if the line width is the same, the dimension of the resist transferred onto the wafer changes if the distance between adjacent patterns is different. For this reason, although dimensional control of the line width of the gate pattern of the logic device is very important, application to the logic device has not been studied much because the logic device includes many random patterns.

In FIG. 8 (c), the pattern 21X has a value of 0.1.
A 16 μm line and space pattern, 21Y is a resist pattern to which a mask pattern designed to be 0.16 μm line / 0.48 μm space is transferred. At this time, the actual size of the resist pattern transferred onto each wafer is 0.1 mm for the pattern 21X.
The pattern 21Y was formed to have a thickness of 0.20 μm.
m, and the dimensional difference between the two was 0.04 μm. In the case of forming a normal transistor gate, since the standard of the dimensional variation is ± 10% of the line width, the line width of 0.16 μm must be suppressed within about 0.03 μm. Therefore, the conventional pattern forming method using a phase shift mask cannot be used for forming a transistor gate pattern requiring high dimensional accuracy.

In order to solve the above problems, the present invention provides a method of forming a fine pattern having a small line width variation using a phase shift mask, and a phase shift mask used for the method.

[0014]

In pattern formation using a Levenson phase shift mask, the phenomenon that the dimension of a resist pattern transferred onto a wafer changes when the distance between adjacent patterns differs even with the same line width is caused by optical proximity. It was found to be due to the effect. In particular, it has been found that the interval between adjacent patterns becomes a remarkable value in a region of 1.0λ / NA or less as a standardized value.

The photomask of the present invention is a photomask that exposes a resist using a photomask in which the phases of the transmission regions on both sides of the light-shielding region are different from each other by 180 degrees to form a resist pattern corresponding to the light-shielding region. The line width of the light-shielding region is corrected according to the interval between adjacent patterns.

Further, the photomask of the present invention is a photomask which forms a line pattern of the same width by exposing a positive resist using a photomask in which the phases of transmission regions on both sides of a light-shielding region are different from each other by 180 degrees. A light-shielding area is newly provided between two light-shielding areas whose distance from an adjacent pattern is equal to or longer than a predetermined distance.

As described above, according to the pattern forming method of the present invention, by using the above-described photomask, the light intensity and the light profile passing through the photomask are changed, or the specific pattern interval is eliminated, so that the different pattern interval is obtained. In this line pattern, the width distribution at the threshold of each light intensity distribution is narrowed, and a resist pattern having substantially the same line width can be formed.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A pattern forming method according to an embodiment of the present invention will be described below with reference to the drawings.

First, a description will be given of an increase in line width variation due to an optical proximity effect in pattern formation using a Levenson phase shift mask.

In the formation of a periodic pattern using a Levenson phase shift mask, an image is formed with only ± first order light near the resolution limit. This light intensity distribution is represented by a sine wave. In particular, at the pattern frequency from the time when all the primary lights are incident to the time when the tertiary light is incident, the light intensity remains constant (the amplitude of the sine wave does not change) and the pattern pitch (the period of the sine wave) is changed. Because of the spread, the pattern line width greatly changes. This corresponds to a region where the slope of the portion having a normalized pattern interval of 1.0 or less in FIG. 5B is steep. This is an optical proximity effect peculiar to the Levenson phase mask, and the dimension largely changes within a very short range as compared with a normal mask. We have found this phenomenon, and the normalized pattern spacing of 1.
By performing the correction on the portion equal to or less than 0, the variation in the pattern line width can be reduced.

(Embodiment 1) FIG. 1 is a sectional view showing a process of a pattern forming method according to Embodiment 1 of the present invention. FIG. 2 is a mask configuration diagram in which a part of the phase shift mask of the present embodiment shown in FIG. 1 is viewed from the wafer side. FIG. 3 shows the distribution of the light intensity formed on the resist.

1 and 2, reference numeral 1 denotes a positive resist, 2 denotes a substrate, and 3A and 3B denote exposure light. Exposure light 3
A is light for illuminating the mask, and exposure light 3B is light that passes through the mask and forms an image on the resist. Reference numeral 4 denotes a photomask, 5, 5A and 5B denote light-shielding areas, 6A and 6B denote transmissive areas, and the transmissive area 6B inverts the phase of the exposure light by 180 degrees with respect to the transmissive area 6A. Hereinafter, the pattern forming method of the present invention will be described with reference to the drawings.

First, in FIG.
Was applied on the substrate 2. The resist was a chemically amplified positive resist for KrF, and the thickness was set to 0.5 μm. Next, in FIG. 1B, the exposure light 3A illuminates the phase shift mask 4, and the positive resist 1 is exposed with the exposure light 3B passing through the mask. The exposure conditions of the stepper were as follows: exposure wavelength λ = 248 nm, numerical aperture NA = 0.48,
A coherent factor σ = 0.40 and a 5: 1 reduction type projection exposure apparatus was used. Phase shift mask 4
Used a digging type in which the phase is changed by 180 degrees by digging a quartz substrate.

The details of the phase shift mask shown in FIG. 1B will be described with reference to FIG. Light shielding area 5 in FIG.
A and 5B are locations where a fine resist pattern is formed on the wafer, and xa and xb indicate the respective widths. The light shielding area 5A is an area where a 0.16 μm line and space pattern is formed on the wafer, and the light shielding area 5B
Is a pattern area with a 0.16 μm line / 0.48 μm space interval, and exists on the same mask. Exposure is 5
The mask pattern is transferred onto the wafer by reducing it by a factor of five, since it is performed by a stepper that is reduced by a factor of one. Therefore, the mask size in FIG. 1B is five times the size of the resist pattern actually transferred. The width xa of the light shielding area 5A used in the present embodiment was 0.80 μm, and the width xb of the light shielding area 5B was 0.50 μm.

FIG. 3A shows the spatial light intensity on the wafer after passing through the mask subjected to the dimension correction of FIG. 2, and FIG. 3B shows the pattern without the mask correction. It shows the spatial light intensity when the light shielding area of the mask is set to 0.80 μm according to the dimensions.

In FIG. 3, the light intensity at which the 0.16 μm line and space is formed 1: 1 by adjusting the exposure amount is indicated by a broken line. Since the resist is a positive resist, a resist pattern is formed below the broken line. Therefore, the line width of the formed resist pattern corresponds to the width of the light intensity distribution indicated by the broken line. In FIG. 3A, a resist pattern of 0.171 μm is formed in a pattern of 0.16 μm line / 0.48 μm space, but in a mask without correction shown in FIG.
It becomes even 0 μm. By adjusting the width of the light-shielding region of the phase shift mask in this way, the light intensity on the wafer can be changed and the dimensions can be adjusted.

Thereafter, the resist exposed at such a light intensity as shown in FIG. 1C is developed for 60 seconds with an aqueous alkali solution after PEB (post-exposure bake treatment) to form a resist pattern 1.
forming x. According to the present embodiment, a resist pattern having a line width of 0.16 μm can be formed with high dimensional accuracy within ± 10%.

As described above, according to the embodiment of the present invention, by changing the width of the light-shielding region of the phase shift mask, the same line width having different pattern intervals can be formed with high precision as designed.

(Embodiment 2) Hereinafter, a pattern forming method according to Embodiment 2 of the present invention will be described with reference to the drawings. FIG. 4 shows the relationship between the 0.16 μm line width and the pattern interval obtained by using a light intensity simulation when a phase shift mask in which the phases of the transmission regions on both sides of the elongated light-blocking region are 180 ° different from each other is used for the positive resist. is there. The simulation conditions were as follows: exposure wavelength λ = 248n
m, numerical aperture NA = 0.60, coherent factor σ =
At 0.3, the light intensity of the threshold is set to a value at which the 0.16 μm line and space pattern becomes 1: 1.

In FIG. 4, a curve a (black circle) indicates a case where no mask correction is performed, and the width of the light-shielding area on the mask of all patterns is converted into a value on the wafer (light-shielding area width × reduction ratio). 0.16 μm similar to the resist pattern
It is. On the other hand, the curve b (open triangle) indicates that the width of the light-shielding region on the mask is set to 0.10 μm in terms of the pattern on the wafer in a pattern in which the pattern interval between adjacent patterns is 0.67 λ / NA or more. It was done. It can be seen that the difference between the maximum value and the minimum value of the line width is reduced to almost half by correcting the width of the light shielding region of the mask.

The reason why mask correction is performed on a pattern in which the distance between adjacent patterns is 0.67 λ / NA or more will be described below.

When mask correction is performed on a pattern in which the interval between adjacent patterns is 0.67 λ / NA or less, FIG.
As is clear from the tendency of the curve b (white triangle), the line width of the actual pattern becomes smaller than 0.16 μm. That is, the interval between adjacent patterns is 0.67λ.
It is considered that the case where the mask correction is not performed for the pattern of / NA or less is closer to the design dimension of 0.16 μm. Therefore, the interval between adjacent patterns is 0.67λ.
It is considered that it is desirable to perform the mask correction only on the pattern of / NA or more.

As described above, in this embodiment, the light-shielding area of the mask of the pattern having the design pattern interval of 0.67 λ / NA or more is set to 0.10 μm in terms of the value on the wafer, and the pattern interval of less than that is used. Was set to 0.16 μm, and the width of two light shielding regions was provided on the mask. by this,
Variation in the line width of the resist pattern can be reduced to half of the conventional one.

In the present embodiment, the width of the light-shielding region of the mask pattern is changed at a pattern interval of 0.67 λ / NA.
The same effect can be obtained by changing the width of the light-shielding region of the mask pattern in the region where the pattern interval is 0.7 λ / NA or more and the region where the pattern interval is 0.7 λ / NA or more.

Embodiment 3 Hereinafter, a pattern forming method according to Embodiment 3 of the present invention will be described with reference to the drawings. FIG. 5 shows the relationship between the line width and the pattern interval when using a phase shift mask in which the phases of the transmission regions on both sides of the elongated light-shielding region differ by 180 degrees for the positive resist, by light intensity simulation and experiments. FIG. 5B shows the line width and pattern interval normalized by λ / NA. In FIG. 5B, the curve a has NA = 0.
60, b show the case of NA = 0.55, and c shows the case of NA = 0.48, respectively. The coherent factor is σ = 0.30 in each case.

As is apparent from FIG. 5, the line width suddenly increases during the pattern interval of 0.5 to 1.0 at all the line widths. The width increases. Thereafter, the line width gradually decreases.

For example, curves a, b, and c in FIG.
Considering c, the line width standardized near the pattern interval of 0.4λ / NA becomes the minimum, and the line width standardized near the pattern interval of 1.0λ / NA becomes the maximum.
Thereafter, the line width gradually decreases as the pattern interval increases. Therefore, in order to suppress variations in line width, the interval between adjacent patterns must be set to the standard value of 0.65λ.
It can be seen that it is only necessary not to use the area below / NA.

Actually, the design rule is determined so that there is no pattern interval less than the standard value 0.7, and the exposure wavelength λ = 248n
m, numerical aperture NA = 0.48, coherent factor σ =
A resist pattern having a line width of 0.16 μm was exposed at 0.40 using a 5: 1 reduction type projection exposure apparatus. The dimensional variation obtained by such a phase shift mask could be suppressed to 0.16 μm ± 10%.

As described above, the dimensional variation can be limited by limiting the interval between the pattern existing on the wafer and the adjacent pattern to 0.65 λ / NA or more.

(Embodiment 4) Hereinafter, a pattern forming method according to Embodiment 4 of the present invention will be described with reference to the drawings. FIG. 6A is a mask configuration diagram illustrating a part of the mask according to the present embodiment viewed from the wafer side, and FIG. 6B is a mask configuration diagram used for the second exposure. () Shows the resist pattern transferred by the second exposure.

FIG. 9A is a diagram showing a part of a conventional phase shift mask viewed from the wafer side.
FIG. 9B is a configuration diagram of a mask used in the second conventional exposure, and FIG. 9C shows a transferred resist pattern. In these figures, reference numeral 15 denotes a light-shielding area,
6A and 16B are transmission regions, and the transmission region 16B inverts the phase of the exposure light by 180 degrees with respect to the transmission region 16A. 1A is a formed resist pattern. FIG. 7 is a diagram showing the slope of the light intensity distribution when the width of the transmission region of the phase shift mask of the present invention is changed.

A pattern forming method using the phase shift mask according to the fourth embodiment will be described in comparison with a conventional example.
In FIG. 6A and FIG. 9A, the fine line pattern on the wafer
More than twice as far apart. In the present embodiment, as shown in FIG. 6A, in a region where adjacent pattern intervals are separated by a predetermined distance (six times the line width) or more, as shown in FIG.
A specific limit width x is set in 6B. That is, regions having phases different by 180 degrees are formed as a pair so that the transmission region is not widened.

On the other hand, in the conventional mask shown in FIG. 9A, since there is no such a specific width, all the areas between the adjacent patterns are the transmission areas 16A and 16B. For this reason, in a pattern having a wide interval, a line width is liable to change because a transmissive region differs depending on the pattern interval.

In the phase shift mask shown in FIG. 6A, a light-shielding region is formed at the center since a transmission region is formed on both sides of the isolated pattern. For this reason,
Although a portion where light should be transmitted is not irradiated with light, the portion may be irradiated with light in a second exposure process for removing upper and lower portions of the fine pattern. The mask (FIG. 6B) used for the second exposure used in the present embodiment has a position corresponding to the light shielding area between the isolated patterns of the phase shift mask as compared with the conventional mask (FIG. 9B). It can be seen that the area is a transmission area.

If the width x of the specific transmission region is determined as in the phase shift mask shown in FIG. 6A, the light intensity passing through the transmission region does not change even if the pattern interval is different, and the dimensional accuracy is high. A resist pattern can be formed. Further, in the conventional phase shift mask as shown in FIG. 9A, since one transmission region is shared by two patterns, it is necessary to always consider the phase when designing the pattern arrangement. However, in the case of FIG. 6A having one pair of left and right transmission regions in one pattern, there is an advantage that a mask can be freely designed regardless of the phase of the transmission region around the light shielding region.

FIG. 7 is a graph obtained by examining the inclination of the light intensity distribution when the transmission area width x of the phase shift mask is changed in an isolated pattern of 0.16 μm by using a simulation. The y-axis of the graph indicates the slope of the light intensity distribution at the light intensity forming a line width of 0.16 μm, and the x-axis indicates the value obtained by converting the transmission area x of the mask onto the wafer (xx × reduction ratio of the projection exposure apparatus). Further, it is standardized to λ / NA.

The simulation conditions were as follows: exposure wavelength λ = 24
8 nm, coherent factor σ = 0.3, curve a (black circle) in the figure is numerical aperture NA = 0.48, curve b (white circle)
Was performed under the condition of a numerical aperture NA = 0.60.
It can be seen that the slope of the light intensity distribution has a peak value in the transmission region width on a specific mask. Generally, the larger the inclination of the light intensity distribution, the larger the margin of the exposure amount with respect to the dimension. This is synonymous with the fact that even if there is a variation in the exposure amount in the pattern irradiation area, if the slope of the light intensity distribution is large, the dimensional variation will be small. Therefore, in order to improve the dimensional accuracy from this drawing, the width x of the transmission area is set to 0.50λ / NA ≦ (xx × reduction ratio of the projection optical system) ≦ 0.
A range of 80λ / NA is preferred.

Actually, the transmission region width x of the phase shift mask of the present invention is set to 0.65λ / NA in terms of dimensions on the wafer, the exposure wavelength λ = 248 nm, and the numerical aperture NA = 0.4.
8. Exposure was performed using a stepper with a coherent factor σ = 0.30. As a result of measuring the size of the formed resist, a dimensional accuracy of 0.16 μm ± 10% was obtained for a 0.16 μm line pattern having a wide pattern interval.

As described above, by providing a specific width in the transmission region of the phase shift mask, a highly accurate pattern can be formed without depending on the pattern interval.

In the embodiment of the present invention, the phase shift mask is a dug-down type, but may be a permeable film laminated type.

[0051]

As described above, according to the present invention, the width of the light shielding region of the phase shift mask is changed according to the line width interval.
Alternatively, by using a mask configuration in which the pattern interval is equal to or more than a certain value or the interval between the transmission regions is always kept constant, it is possible to reduce dimensional variations due to the optical proximity effect that occurs when using a phase shift mask.

[Brief description of the drawings]

FIG. 1 is a process sectional view of a pattern forming method according to a first embodiment of the present invention;

FIG. 2 is a configuration diagram of a mask used in a pattern forming method according to the first embodiment of the present invention;

FIG. 3 is a diagram showing a light intensity distribution of the pattern forming method according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a relationship between a line width and a pattern interval in a pattern forming method according to a second embodiment of the present invention;

FIG. 5 is a diagram showing a relationship between a line width and a pattern interval in a pattern forming method according to a third embodiment of the present invention.

FIG. 6 is a diagram illustrating a pattern forming method according to a fourth embodiment of the present invention.

FIG. 7 is a diagram showing a relationship between a transmission area and a slope of a light intensity distribution in a pattern forming method according to a fourth embodiment of the present invention.

FIG. 8 is a process sectional view of a conventional pattern forming method.

FIG. 9 is a view for explaining a conventional pattern forming method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Positive resist 2,22 Substrate 3A, 3B, 23A, 23B Exposure light 4 Mask 5,5A, 5B, 15,25 Light shielding area of mask 6,6A, 6B, 16A, 16B, 26A, 26B Transmission area of mask

Claims (14)

[Claims] 1. A photomask for exposing a resist using a photomask in which the phases of transmissive regions on both sides of a light-shielding region are different from each other by 180 degrees to form a resist pattern corresponding to the light-shielding region. A photomask, wherein a line width is corrected according to an interval between adjacent patterns. 2. The photomask according to claim 1, wherein the resist pattern is a pattern having the same width and an arbitrary interval. 3. The distance between adjacent resist patterns is 0.7.
The distance between the light-shielding region on the mask for forming a pattern of λ / NA or more and the adjacent resist pattern is 0.5 λ / NA.
3. The photomask according to claim 2, wherein the width of the light-shielding region is made different from that of the light-shielding region on the mask on which the following pattern is formed. 4. A photomask in which a positive resist is exposed using a photomask in which the phases of transmissive regions on both sides of a light-shielding region are different from each other by 180 degrees to form a line pattern having the same width, wherein the distance between adjacent patterns is A photomask, wherein a new light-shielding region is provided between two light-shielding regions that are longer than a predetermined distance. 5. A width x of a transmission region between a light shielding region and a newly provided light shielding region is defined as: 0.5λ / NA ≦ (width x of transmission region) × (reduction ratio of projection optical system) ≦ 0.8λ. 5. The photomask according to claim 4, wherein the ratio is / NA. 6. The photomask according to claim 4, wherein an interval between adjacent patterns is at least six times a pattern line width. 7. A pattern forming method for exposing a resist using a photomask in which phases of transmission regions on both sides of a light-shielding region differ from each other by 180 degrees to form a resist pattern corresponding to the light-shielding region. Using a photomask whose line width has been corrected in accordance with the interval between adjacent patterns. 8. The pattern forming method according to claim 7, wherein the resist pattern is a pattern having an arbitrary interval and having the same width. 9. The method according to claim 1, wherein an interval between adjacent resist patterns is 0.7.
The distance between the light-shielding region on the mask for forming a pattern of λ / NA or more and the adjacent resist pattern is 0.5 λ / NA.
9. The pattern forming method according to claim 8, wherein a photomask in which the width of the light shielding region is different from that of the light shielding region on the mask for forming the following pattern. 10. A pattern forming method for exposing a positive resist using a photomask in which phases of transmission regions on both sides of a light shielding region are different from each other by 180 degrees to form a line pattern having the same width, wherein a distance between adjacent patterns is defined. Using a photomask in which a light-shielding region is newly provided between the two light-shielding regions which are longer than a predetermined distance. 11. A width x of a transmission region between a light shielding region and a newly provided light shielding region is set to 0.5λ / NA ≦ (width of transmission region x) × (reduction ratio of projection optical system) ≦ 0.8λ / 11. The pattern forming method according to claim 10, wherein a photomask having an NA is used. 12. A pattern forming method for exposing a resist using a photomask in which the phases of transmissive regions on both sides of a light-shielding region are different from each other by 180 degrees to form a resist pattern corresponding to the light-shielding region. A pattern forming method, wherein a pattern interval is at least 0.65λ / NA or more. 13. A step of applying a positive resist on a semiconductor substrate and a phase of a transmission region on both sides of a light-shielding region for forming a circuit pattern are different from each other by 180 degrees, and a line width of the light-shielding region depends on an interval between adjacent patterns. A semiconductor device including a step of exposing a resist using a photomask corrected by exposure and a step of removing an unnecessary resist pattern by exposing a portion necessary for a circuit pattern to light using a second exposure mask that shields light. Manufacturing method. 14. A step of applying a positive resist on a semiconductor substrate, and two steps in which the phases of transmission regions on both sides of a light-shielding region for forming a circuit pattern are different from each other by 180 degrees, and the distance between adjacent patterns is a predetermined distance or more. A step of exposing the resist using a photomask in which a light-shielding area is newly provided between the light-shielding areas, and a step of exposing the resist necessary for the circuit pattern by using a second exposure mask that shields light. A method of manufacturing a semiconductor device, comprising a step of removing an unnecessary resist pattern including a resist pattern corresponding to a light-shielded region.