JP2000330259A - Mask and exposure method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a mask with which line widths of high resolution may be obtained by double exposure of periodic pattern exposure and ordinary pattern exposure and an exposure method. SOLUTION: This mask is used for the periodic pattern exposure when circuit patterns are transferred onto a photosensitive substrate by executing the double exposure of the ordinary pattern exposure and the periodic pattern exposure and has plural periodic patterns 1 and 2. When the spacing between a line P1a and line P1a of one periodic pattern among these plural periodic patterns 1 and 2 is defined as S, the spacing D between the adjacent two periodic patterns 1 and 2 is 0.5S<D<1.5S.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mask and an exposure method using the same, and more particularly to a mask and an exposure method used for exposing a photosensitive substrate with a fine circuit pattern.
For example, it is a mask or an exposure method suitable for manufacturing various devices such as semiconductor chips such as ICs and LSIs, display elements such as liquid crystal panels, detection elements such as magnetic heads, and imaging elements such as CCDs.

[0002]

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

In recent years, the above-mentioned projection exposure method and projection exposure apparatus, which form the center of microfabrication technology for wafers,
Image (circuit pattern image) with dimensions (line width) of 0.5 μm or less
In order to form an image over a wide range, the resolution is increased and the exposure area is increased.

On the other hand, a projection exposure apparatus using an excimer laser as a light source, which is becoming mainstream at present, has a high projection resolution, but it is technically difficult to form a pattern image of, for example, 0.15 μm or less.

In contrast, US Pat. No. 5,415,8
No. 35 discloses a technique for forming a fine pattern by two-beam interference exposure. According to the two-beam interference exposure, a pattern having a line width of 0.15 μm or less can be formed on a wafer.

The applicant of the present invention has disclosed, for example, Japanese Patent Application No. 10-2210.
No. 95, Japanese Patent Application No. 10-210333, Japanese Patent Application No. 10-2
No. 21097 and the like, an exposure method capable of creating a circuit pattern having a portion of 0.15 μm or less by performing double exposure of periodic pattern exposure and normal exposure on a substrate to be exposed (photosensitive substrate). Is shown.

[0007] The "normal exposure" here is an exposure which has a lower resolution than the periodic pattern exposure but is capable of exposing in an arbitrary pattern. As a typical example, a mask pattern is projected by a projection optical system. Exposure.

The pattern exposed by the normal exposure includes a fine pattern having a resolution equal to or less than a resolution (hereinafter, referred to as a “normal exposure pattern”). The periodic pattern exposure forms a periodic pattern having a line width similar to that of the fine pattern. Is what you do. A Levenson type phase shift mask or the like is used for this periodic pattern exposure.

FIG. 23 is a simple explanatory view of double exposure.
The periodic pattern shown in FIG. 23A and the normal exposure pattern shown in FIG. 23B are subjected to multiple exposure at the same position.
The composite pattern (image) of (C) is obtained. The principle of the multiple exposure will be described later.

[0010]

FIG. 24 is a diagram for explaining a problem that occurs when a fine pattern is formed by double exposure of a periodic pattern and a normal exposure pattern. 2, (B) is a relationship between normal patterns 1 and 2, (C) is a schematic view of a superimposed pattern by double exposure, and (D) is a pattern between design patterns 1 and 2 formed by a light transmitting portion. The case is shown as an example. The purpose of this double exposure is to finally create the two design patterns (D).

Here, the normal exposure pattern shown in FIG. 24B is a pattern similar or similar to the design pattern (D), and it is originally necessary to consider the magnification of the exposure apparatus. It is easily shown as a magnification of 1.

The periodic pattern of FIG. 24A focuses on the fine line portion of the normal exposure pattern (B), and has the same pitch as the pattern obtained by extracting only these fine lines. In other words, each of the two patterns (A) periodic pattern,
The pitches of (B) the normal exposure pattern and (C) the design pattern are equal.

(A) The number of periods of the periodic pattern is
The number is set to be equal to or greater than the number of patterns obtained by extracting only these fine lines.

As described above, the shapes of the periodic patterns 1 and 2 are determined according to the design patterns 1 and 2.
It has been found that, depending on the value of the interval D between competitors, when the periodic pattern is exposed, disorder of the cycle, that is, disorder of the pattern occurs at the boundary between the periodic pattern 1 and the periodic pattern 2.

For example, here, the pitch P of the periodic pattern 1
It has been found that when the pitch P2 of the periodic pattern 2 is different from the pitch P2 of the periodic pattern 2, a periodic disturbance occurs at the boundary between the periodic patterns 1 and 2.

The pitches P1, P2 of the design patterns 1, 2
Even when P1 = P2 where the relationship of P2 is equal, the periodic pattern may be disturbed by the arrangement of the design pattern. The width of a line constituting one pitch of the periodic pattern is L,
An example of L = S when the width of the space is S will be described. When it is desired to create design patterns 1 and 2 in which the design pattern interval DS is an odd multiple of L or S, the interval D between the periodic patterns 1 and 2 is equal to the width S of the space. No disturbance occurs.

However, when the interval DS is an even multiple of L or S, the interval D between the periodic patterns 1 and 2 is D =
2S, which causes disturbance in the periodic pitch at the boundary between the two patterns. Also, when the interval DS between the design patterns 1 and 2 is not an integral multiple of S, the interval between the periodic patterns 1 and 2 does not become D = S, which does not disturb the period, and the period is disturbed.

As described above, since the periodic pattern is determined in accordance with the design pattern, in the present situation where patterns are densely used, these patterns are used in obtaining multiple patterns by multiple exposure depending on the positional relationship between two adjacent design patterns. There is a situation where it is unavoidable to disturb the period at the boundary between two adjacent periodic patterns in the periodic pattern exposure. An object of the present invention is to provide a mask and an exposure method which can reduce the disturbance of the period.

[0019]

According to a first aspect of the present invention, a mask is provided.
When a plurality of periodic patterns are provided, and one of these periodic patterns has a line-to-line interval S, the interval D between the one periodic pattern and another periodic pattern adjacent thereto in the periodic direction is: It is characterized in that 0.5S <D <1.5S.

The mask according to the second aspect of the present invention has a plurality of periodic patterns. When the interval between the lines of one of the periodic patterns is S, the one periodic pattern and the other adjacent thereto are arranged. It is characterized in that the interval D between the periodic patterns is 0.9S <D <1.1S.

According to a third aspect of the present invention, in the first or second aspect, the phases of the patterns (lines or spaces) located at respective boundaries between the two adjacent periodic patterns are opposite to each other. Features.

A mask according to a fourth aspect of the present invention is a mask having a plurality of periodic patterns, wherein phases of two lines (lines or spaces) located at respective boundaries of two periodic patterns adjacent in the periodic direction are mutually different. It is characterized by being in antiphase.

According to a fifth aspect of the present invention, there is provided an exposure method including exposing a photosensitive substrate using the mask according to any one of the first to fourth aspects.

The multiple exposure method according to a sixth aspect of the present invention includes the first to fourth
The present invention is characterized in that it includes exposure using one of the masks of the invention and exposure using another mask.

An exposure apparatus according to a seventh invention is characterized in that it has an exposure mode for executing the exposure method of the fifth or sixth invention and an exposure mode for executing another exposure method.

According to an eighth aspect of the invention, there is provided a device manufacturing method comprising the steps of exposing a wafer with a device pattern using the exposure method of the fifth or sixth aspect, and developing the exposed wafer. Features.

A ninth aspect of the present invention is a mask having a first and a second periodic pattern. Each of the first and the second periodic patterns has a pitch P of one line and a space. And the pitch of the first periodic pattern is P
1, the line width is L1, the space width is S1, and the pitch of the second periodic pattern is P2, and the line width is L.
2. The width of the space is S2, the pitch P1 and the pitch P2 are different from each other, the first and second periodic patterns are adjacent to each other in a periodic direction, and the first and second periodic patterns are adjacent to each other. The interval D is the width S1, S2 of the space.
Is S and one of the line widths L1 and L2 is L, and if L <S, then 0.5L ≦ D ≦
S + 0.5L, 0.5S ≦ D ≦ L + 0 if S ≦ L.
It is characterized by being within the range of 5S.

A mask according to a tenth aspect of the present invention is a mask having first and second periodic patterns, wherein each of the first and second periodic patterns has one pitch composed of lines and spaces. , The pitch of the first periodic pattern is P
1, the line width is L1, the space width is S1, the second
Has a pitch P2, a line width L2, and a space width S2. The pitch P1 and the pitch P2 are different from each other, and the first and second periodic patterns are adjacent to each other in a periodic direction. The interval D between the first and second periodic patterns is equal to the width S1 of the space and the width S2 of the space.

The mask according to an eleventh aspect of the present invention is a mask having a plurality of periodic patterns, each of the periodic patterns having a pitch of one line and a space, and having a pitch equal to each other adjacent to each other in the periodic direction. It has two periodic patterns, and the interval D in the periodic direction between the two periodic patterns is L <S when the line width is L and the space width is S. Time is 0.5
Satisfies L ≦ D <S or S <D ≦ S + 0.5L, and S ≦ L
At the time of, 0.5S ≦ D <L or S <D ≦ L + 0.5S is satisfied.

The exposure method according to the twelfth invention is directed to the ninth to eleventh exposure methods.
The photosensitive substrate is exposed by using any one of the masks according to the present invention.

According to a twelfth aspect of the present invention, there is provided a multiple exposure method comprising the steps of: using one of the masks according to the ninth to eleventh aspects and exposing using another mask.

An exposure apparatus according to a fourteenth aspect has an exposure mode for executing the twelfth or thirteenth exposure method and an exposure mode for executing another exposure.

According to a fifteenth aspect of the invention, there is provided a device manufacturing method comprising:
The method includes a step of exposing a wafer with a device pattern using the second or thirteenth exposure method, and a step of developing the exposed wafer.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an example of double exposure (multiple exposure) to which a mask and an exposure method according to the present invention are applied will be described.

FIGS. 1 to 9 are explanatory views showing the principle of this double exposure (multiple exposure) example. FIG. 1 is a flowchart showing a basic procedure of exposure. FIG. 1 shows the blocks and the flow of the development step in addition to the periodic pattern exposure step and the projection exposure step (normal pattern exposure step) constituting the double exposure. In the figure, the order of the periodic pattern exposure step and the projection exposure step may be reversed, and when one of the steps includes a plurality of exposure steps, each step may be performed alternately. or,
There is a step of performing precise alignment between each exposure step.

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

Here, the multiple exposure means that the photosensitive substrate is exposed a plurality of times with different patterns without going through the developing process. In addition, the normal pattern exposure is exposure in which the resolution is lower than that of the periodic pattern exposure, but the exposure can be performed in an arbitrary pattern. A typical example is exposure in which a mask pattern is projected by a projection optical system.

The pattern (normal pattern) exposed by the normal exposure includes a fine pattern having a pattern under the combination of an exposure apparatus and a mask to be used and having a resolution equal to or less than the resolution, and the periodic pattern exposure is substantially the same as the fine pattern. A periodic pattern having a line width of the order is formed. The line width of a pattern larger than the resolution of the normal pattern exposure is larger than the minimum line width of the pattern of the periodic pattern exposure, and its size is not limited. For example, a line width of an integral multiple of this minimum line width is effective. is there.

The shape of a large pattern having a resolution higher than the above-mentioned resolution of the normal pattern exposure is arbitrary, and the line thereof may be directed in various directions. Generally, in the case of an IC pattern, the direction of the pattern is often directed in two directions, that is, a certain direction and a direction orthogonal thereto, and the direction of the finest pattern is limited to only one of these two directions. There are many.

When periodic pattern exposure is performed by double exposure, it is important that the longitudinal direction of each of the periodic patterns coincides with the longitudinal direction of the finest pattern of the normal patterns.

Further, the exposure is performed so that the peak (center) of the exposure distribution of a pattern having a periodic pattern coincides with the center of the exposure distribution of the finest pattern having a resolution lower than that of the normal pattern.

The double exposure in the present invention means a double exposure of a periodic pattern exposure and a normal pattern exposure. In the periodic pattern exposure, each pattern is formed in parallel with the direction of the finest pattern of the normal pattern exposure. It may be performed repeatedly as many times as possible.

Each of the periodic pattern exposure and the normal pattern exposure of the exposure method and exposure apparatus of the present invention is performed once or
When a plurality of exposure steps are performed and a plurality of exposure steps are performed, a different exposure amount distribution is given to the photosensitive substrate for each exposure step.

When exposure is performed according to the flow of FIG. 1, first, a wafer (photosensitive substrate) is
Exposure is performed in a periodic pattern as shown in FIG. The numbers in FIG. 2 represent exposure amounts, and the hatched portions in FIG.
(Actually arbitrary) and the exposure amount is 0 in the white portion.

When developing only such a periodic pattern after exposure, usually, the exposure threshold value E of the resist on the photosensitive substrate is used.
th is set between the exposure amounts 0 and 1 as shown in the lower graph of FIG. The upper part of FIG. 2B shows a lithography pattern (a convex pattern in the case of a negative type) finally obtained by performing development etching after exposure under such a setting.

FIG. 3 shows a positive resist (hereinafter referred to as "positive") showing the relationship between the exposure threshold and the exposure dependency of the film thickness after development with respect to the resist on the photosensitive substrate in this case.
And a negative type resist (hereinafter referred to as “negative type”). The film thickness after development becomes 0 when the exposure is equal to or more than the exposure threshold value Eth in the case of the positive type and is equal to or less than the exposure threshold value Eth in the case of the negative type.

FIG. 4 is a schematic diagram showing a state in which a lithography pattern is formed through the development and etching processes when such exposure is performed, for a negative type and a positive type.

In this embodiment, unlike the normal exposure sensitivity setting, FIGS. 5 (same as FIG. 2A) and FIGS.
As shown in the lower part of the figure, when the exposure amount at the center of each pattern in the periodic pattern exposure is 1, the exposure threshold value Eth of the resist on the photosensitive substrate is set to be larger than 1 and smaller than 2. When the exposure pattern (exposure amount distribution) obtained by performing only the periodic pattern exposure shown in FIG. 2 is developed, the exposure amount of the photosensitive substrate having such an Eth setting is insufficient. The film thickness becomes 0 by development
No lithography pattern is formed by etching as shown in the upper part of FIG. This can be regarded as the disappearance of the periodic pattern (note that the present invention will be described using an example using a negative type, but the present invention can also be implemented in a positive type).

[0049] Incidentally, E ₁ according to the lower part of FIG. 6 is an exposure amount in the periodic pattern exposure, E ₂ represents an exposure amount in the conventional projection exposure.

In this embodiment, a fine exposure pattern, which is apparently lost only by the periodic pattern exposure, is fused with an exposure pattern of an arbitrary shape including a pattern having a size smaller than the resolution of the exposure apparatus by a normal exposure to a desired area. Only the resist is exposed more than the exposure threshold value, so that a desired lithography pattern corresponding to the circuit pattern can be finally formed.

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

Projection exposure for forming the exposure pattern shown in FIG.
Without the development step after the periodic pattern exposure of FIG.
Assuming that the process is performed on the same area of the same resist,
The total exposure distribution on the resist surface is shown in the lower part of FIG.
It becomes like the graph of. Here, periodic pattern exposure
Exposure E₁ And the exposure E of the projection exposure_Two Ratio is 1: 1,
The exposure threshold Eth of the dist is the exposure amount E₁ (= 1),
Exposure E₁ And exposure amount E _Two Sum E with₁ + E_Two (= 2)
The lithography shown at the top of FIG.
A lithographic pattern (convex pattern in the case of a negative type) is formed
Is done.

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

The isolated line pattern shown in the upper part of FIG. 7 (B) has a resolution of periodic pattern exposure and is not a simple periodic pattern. Therefore, a fine pattern with a higher resolution than the resolution that can be realized by a single projection exposure is obtained by the multiple exposure.

Here, it is assumed that the normal exposure for forming the exposure pattern shown in FIG. 8 (exposure amount equal to or larger than the exposure threshold value with a line width twice as large as the exposure pattern shown in FIG. 5 (here, the exposure amount twice as large as the threshold value)) 5) is superimposed on the same region of the same resist without the development step after the periodic pattern exposure of FIG. At this time, by making the center of the exposure pattern of the normal exposure coincide with the peak position of the exposure pattern of the periodic pattern exposure, the superimposed pattern has good symmetry and a good pattern image can be obtained.

The total exposure distribution of the resist when such multiple exposure is performed is as shown in the lower part of FIG.
The exposure pattern of the two-beam interference exposure (periodic pattern exposure) disappears, and finally only the lithography pattern (convex pattern in the case of a negative type) shown in the upper part of FIG.

As shown in FIG. 9, the principle is the same when projection exposure is performed with a line width three times as large as the exposure pattern of FIG. In an exposure pattern having a line width, the line width of a finally obtained lithography pattern will be obvious from a combination of an exposure pattern having a double line width and an exposure pattern having a triple line width. All lithography patterns that can be realized by projection exposure can be formed in this embodiment.

By adjusting the exposure amount distribution (absolute value and distribution) and the threshold value of the resist on the photosensitive substrate by each of the periodic pattern exposure and the normal exposure briefly described above,
The minimum line width is composed of a combination of various patterns as shown in FIG. 6, FIG. 7 (B), FIG. 8 (B), and FIG.
(Pattern (B)) can be formed.

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

(A-2) Regarding the pattern area of the normal exposure performed with the exposure amount equal to or less than the exposure threshold value of the resist, the periodic pattern exposure is determined by a combination of the normal exposure exposure pattern and the periodic pattern exposure pattern. A pattern having a line width of one pattern is formed.

(A-3) The same pattern (corresponding to the mask pattern) as the exposure pattern is formed in the exposure pattern area of the normal exposure performed with the exposure amount not less than the exposure threshold value.
It turns out that. Further, as an advantage of the multiple exposure method described above, if the periodic pattern exposure having the highest resolution is performed by two-beam interference exposure, a much larger depth of focus can be obtained as compared with the normal exposure.

In the above description, the order of the periodic pattern exposure and the normal exposure is the cycle pattern exposure first. However, the normal exposure may be performed first or simultaneously.

Next, Embodiment 1 of the present invention will be described.

FIG. 10 is an explanatory view of a periodic pattern according to the first embodiment of the mask (reticle) of the present invention. This mask is used when the periodic pattern exposure in the multiple exposure is performed by a projection exposure apparatus. This embodiment shows a case where periodic patterns 1 and 2 having the same pattern pitch are adjacent to each other in the periodic direction. The mask of this embodiment has a plurality of periodic patterns, and FIG.
One periodic pattern is shown. In each periodic pattern, a line having a width L (hereinafter, referred to as “line L”) of a light transmitting portion and a space having a width S (hereinafter, referred to as “space S”) between adjacent lines L are periodically alternated. Are arranged. Here, the pitch P of each periodic pattern is P = L + S. Further, in the figure, a portion where 0 or π is described is a slit (transmitting portion), and a portion around the slit is a light shielding portion. 0 and π represent the phase of the transmitted light.

Hereinafter, the periodic pattern 1 and the periodic pattern 2 will be described in the case of using the L / S Levenson type phase shift mask pattern having the same pitch and the line width and the space width of 0.12 μm and 0.12 μm, respectively. The patterns P1a and P2a at the respective boundary positions of the periodic patterns 1 and 2 are lines L having phases opposite to each other. Hereinafter, an example in which a mask is illuminated by partial coherent illumination with σ = 0.2 and projected and exposed will be described.

In this case, in each of the periodic patterns 1 and 2, the width of each of the line L and the space S is 0.12.
Since the interval D between the two periodic patterns 1 and 2 is 0.12 μm, which is the same as the width of the space S, there is no disturbance in the period near the boundary between the two periodic patterns as described later. . However, these two periodic patterns 1 and 2
When the interval D is other than 0.12 μm, the periodic characteristics (characteristics of the periodic pattern image) of both patterns near the boundary between the two patterns are disturbed.

Then, in order to grasp the influence of the disturbance of the periodic characteristics, the relationship between the interval between the periodic patterns and the region where the influence is exerted is shown in the graph of FIG. The horizontal axis of each graph in FIG. 11 indicates the interval D between the periodic patterns, and the vertical axis of each graph indicates the region affected by the boundary as shown in FIG. 10 by the distance from the boundary. The “influenced area” refers to a case where the reproducibility of the line width has a change of ± 2.5% or more with respect to the designed line width of 0.12 μm, or the pattern at the center of the periodic pattern with respect to the contrast. Was determined to have a change of ± 2.5% or more with respect to the contrast. The degree of influence of the boundary is the largest at the boundary and gradually decreases as the distance from the boundary increases, indicating how far the boundary is affected. S in the figure is the width of the space S shown in FIG.

FIG. 11 shows that when the pattern interval D between the periodic pattern 1 and the periodic pattern 2 is separated to infinity, the influence of the boundary extends to 0.84 μm, but the interval D between the periodic patterns is reduced. The area of influence gradually becomes narrower, and the interval D between the periodic patterns becomes
It can be confirmed that there is no influence of the boundary when the interval is 0.12 μm, which is the same as the width of. Further, if the interval is made smaller than S, the area affected by the boundary becomes gradually wider and 0.5S
(0.06 μm) or less has a greater effect than in the case of infinity. 0.5S to 1.5S (0.06 to 0.18μ
In the case of m), there is no greater effect than in the case of infinity.

That is, the interval D between the periodic patterns is set to 0.
In the case of 5S (0.06 μm) to 1.5S (0.18 μm), the affected area is smaller than when the patterns are separated from each other to an infinite area.

As a result, the area affected by the pattern boundary changes depending on the interval D between the periodic patterns, so that the interval D between the periodic patterns is infinitely larger than 0.5S to 1.
5S (0.5L to 1.5L) interval (preferably 0.9L
It can be understood that the closer the distance is to (S to 1.1S), the less the influence of the boundary.

The most preferable case is that the interval D between the two periodic patterns 1 and 2 is S (0.12 μm) as described above, but the two periodic patterns can be arranged next to each other at the most preferable interval. Not necessarily. In such a case, a good pattern can be obtained by taking into account the above-mentioned effects and (a) not using the affected area (b) correcting the OPC or the like and using it just before the boundary.

(A) When the affected area is not used When the two periodic patterns cannot be arranged next to each other at the most preferable pattern interval 1S (0.12 μm), the area affected by the boundary is determined based on FIG. There is one method that is not used.

As an example, FIG. 12 shows a mask (reticle) in which the interval D between two periodic patterns in FIG. 10 is 0.16 μm. This mask is also used when the above-described periodic pattern exposure is performed by the projection exposure apparatus, and the symbols in FIG. 12 have the same meanings as those in FIG. FIG. 11 shows that when the interval D between the periodic patterns is 0.16 μm, the area affected by the boundary is 0.48 μm from the boundary. Therefore, 0.48 μm from the boundary
The influence is eliminated by arranging the normal exposure pattern at a separated position.

As described above, by arranging a mask pattern for normal exposure so as not to use an area having an influence of a boundary in each periodic pattern, a pattern image superimposed by multiple exposure without being affected by a boundary. Is formed.

Next, the case where attention is required will be described separately for each interval between periodic patterns. In the present embodiment, the line width and the space width are taken as 0.12 μm as an example, but the line width and the space width of each periodic pattern are not limited to these values.

The interval D between the periodic patterns is 0.5S
(0.06 μm) or less (see FIG. 11) In this case, the influence of the boundary is larger than the case where the interval between the two periodic patterns is infinite, so that the pattern forming the periodic pattern as shown in FIG. One interval is removed and the interval D between the periodic patterns is set to be larger than 2S (0.24 μm) and equal to or smaller than 2.5S (0.28 μm). FIG.
3 shows a case where the interval between the periodic patterns is 0.5S, and the interval between the periodic patterns is set to 2.5S by removing one pattern constituting the periodic pattern. However, the interval D between the periodic patterns is 2S
(0.24 μm) in accordance with the following.

The interval D between the periodic patterns is 2S (0.
When the interval D between the periodic patterns is larger than 2S, the number of patterns constituting the periodic pattern is increased as shown in FIG. 14 so that the interval D is 0.5S (0.06 μm) or more. 1.5S
(0.18 μm). FIG. 14 shows a case where the interval between the periodic patterns is 5S. By increasing the number of the patterns constituting the periodic pattern by two,
The interval between the periodic patterns is S.

The interval D between the periodic patterns is 1.5S or more.
In the case of 2S (in the case of a light transmission type mask) In a negative resist, when exposing a circuit pattern, a mask whose pattern portion is a light transmission portion is usually used.
Also, when exposing the contact holes with a positive resist, a mask whose pattern portion is a light transmitting portion is used. Care must be taken when the interval D between the periodic patterns is 1.5S (0.18 μm) to 2S (0.24 μm) in such a light transmission type mask.

FIG. 16 shows the case where the periodic pattern interval D in FIG. 10 is 2S (0.24 μm) and the case where the periodic pattern interval D is 20S (2.4
The one-dimensional intensity distribution of the periodic pattern image in the case of isolation of μm) was shown. If the interval D between the periodic patterns is 2S and the interval between the periodic patterns cannot be regarded as isolated as compared with the case where the interval between the periodic patterns is 20S and the interval between the periodic patterns can be regarded as isolated, the strength of the boundary portion is emphasized. I understand. The tendency is that the interval between periodic patterns is 1.5S
It becomes remarkable above, and this interval becomes the strongest at 2S.
This phenomenon appears more as the line width becomes smaller.

When such a light transmission type mask is used, an image of the design pattern is formed at a place where the light intensity is strong, and when the intensity is enhanced at the boundary, the pattern is enhanced only there. In this case, the boundary may be formed as an image, which is a problem. On the other hand, in the case of a light-shielding type mask, an image of a design pattern is formed at a position where the light intensity is close to 0, so that there is no problem that occurs in the light-transmitting type mask.

For the above reasons, in the case of the light transmission type mask, when the interval D between the periodic patterns is 1.5S to 2S, it is possible to change the pattern arrangement, to set the illumination conditions in double exposure, It is necessary to optimize the light amount ratio and set so that the light intensity of the pattern near the boundary is not too strong.

When the interval D between the periodic patterns is 2S (0.
24 μm) If it is possible to make the interval between the periodic patterns 2S (0.24 μm), that is, one pitch, it is desirable to avoid it. As shown in FIG. 16, in the case of 0.24 μm, the enhancement of the light intensity at the boundary is most remarkable, and both the contrast and the line width change more than in the case of isolation. When the interval between the periodic patterns is 2S, as shown in FIG. 15, one of the periodic patterns is removed by 4S (0.4S).
8 μm).

To summarize the above, when two periodic patterns having the same width and pitch of the line L and space S are arranged adjacent to each other in the periodic direction, the adjacent patterns P1a and P2a at the boundaries are lines having opposite phases. When adjacent periodic patterns are adjacent to each other, it is best to separate them by the same width as the space S. However, when such an arrangement cannot be made, at least an interval of 0.5S or more and 1.5S or less (S is the width of the space). It is good to adjust.

If the interval D between the periodic patterns is less than 0.5S, one of the periodic patterns is eliminated and the interval D between the periodic patterns is adjusted to be larger than 2S and less than 2.5S (S is Space width). When the interval between the periodic patterns is 2S, one of the periodic patterns is eliminated, and the periodic patterns are arranged at intervals of 4S (S is the width of the space). Further, when the interval between the periodic patterns is wider than 2S, the periodic pattern is extended in the periodic direction by adding the boundary position pattern, and the interval between the periodic patterns is adjusted to be 0.5S or more and 1.5S or less (S Is the width of the space). In the case of the above-described light transmission type pattern, when the interval between the periodic patterns is 1.5S to 2S, it is necessary to consider the light amount ratio and the illumination conditions when performing double exposure (S is Pace width).

What has been described above is an example of a periodic pattern having a limit resolution of a line width K1 factor of 0.29 and a pitch K1 factor of 0.58, in which the intervals between periodic patterns can be regarded as isolated. In the case, 7 from the boundary
The influence is exerted on the region L away. As a result, the influence of the boundary is gradually weakened in a portion where the pitch is large. When the K1 factor of the line width is 0.36 and the K1 factor of the pitch is 0.73, the area affected by the boundary becomes 4L. Here, the case where the width of the line L and the width of the space S of the periodic pattern are the same, 0.12 μm, has been described.
The same applies to the case where the width of the line L and the width of the space S are different from each other at 0.24 pitch. 0.5L when L <S
≦ D ≦ S + 0.5L, 0.5S ≦ D ≦ L + when S ≦ L
It is desirable to be within the range of 0.5S. Here, the factor K1 is obtained from the following equation, where L is the minimum line width or the minimum pitch of the pattern, NA is the numerical aperture of the illumination optical system, and λ is the wavelength. K1 = L × (NA / λ)

(B) OP for using the affected area
When C is applied This is a case where the periodic patterns cannot be arranged at the most preferable intervals, and when the pattern is used up to the boundary, the pattern of the boundary is corrected by OPC (Optical Proximity Effect Correction) based on the degree of influence of the boundary.

FIG. 17 shows the relationship between the pattern interval and the line width deviation from the design value of the periodic pattern when the interval D between the periodic patterns in FIG. 10 is 0.06 μm, 0.24 μm, and infinity. It is. The horizontal axis indicates the number of patterns counted from the boundary, and the vertical axis indicates a line width deviation from the line width of 0.12 μm, which is a design value of the line width of each pattern of the periodic pattern.

FIG. 17 shows that, for example, when the pattern interval is infinite, there is a line width difference from the design value up to the third end from the boundary side. It can be said that this difference in line width is the effect of the pattern being at the boundary. Therefore, considering the line width deviation also appearing on the vertical axis, the OPC
And so on, the influence of the boundary can be eliminated.

An example of OPC will be described.

When the interval D between the periodic patterns is infinite, the difference between the design value and the line width occurs up to the third line as described above with reference to FIG. Specifically, the first pattern: +0.0
It can be seen from FIG. 17 that the first and second lines have a line width difference of −0.01 and the third line has a line width of −0.005. Therefore, in image plane conversion, 0.12-0.01 for the first line, 0.12-0.03 for the second line, and 0.12 + 0.005 for the third line.
By creating a mask (reticle) having a periodic pattern in which the line widths of the three patterns are corrected, it is possible to prevent the influence of the boundary from being reflected on the pattern. However, in this case, the center of the pattern is adjusted to match the case without correction, and the pitch of the three patterns is adjusted at intervals between the patterns so as not to be different from the pitch of the entire periodic pattern.

Here, the amount of OPC is determined based on the line width deviation from the design value, but the method of determining OPC is not limited to this method. Either the periodic pattern or the normal exposure pattern may be corrected by the OPC.

In the present embodiment, as an example of two periodic patterns having the same pitch, a case where the line width and the space width are equal to each other in the two periodic patterns has been described, but the present invention is not limited to this. When the line width and the space width are different, the symbol S used in each of the above conditions is either the line width or the space width.

In the present embodiment, it is assumed that the patterns at the boundary positions of the two periodic patterns have phases opposite to each other. The reason is that, when the patterns at the boundary between two periodic patterns are in phase with each other, if the periodic patterns are brought closer by 2S or more, the pattern is not resolved, and the pattern light intensity is emphasized at the boundary. Therefore, it is necessary to keep the interval between the minimum period patterns at least 2S or more, and if the phases are reversed, a dense pattern can be created.

Next, a second embodiment of the mask of the present invention will be described. This mask is also a mask (reticle) used when performing the periodic pattern exposure in the multiple exposure using a projection exposure apparatus.

In the second embodiment, the pitches are different from each other.
One periodic pattern is a case of a mask adjacent in the periodic direction, and its outline is shown in FIG. The periodic pattern 1 is a phase shift mask pattern having a pitch of 0.24 μm, and the periodic pattern 2 is a phase shift pattern having a pitch of 0.3 μm. Pattern P1 at the boundary of these periodic patterns
a, P2a are lines having opposite phases, and σ = 0.2
An example in which the mask is illuminated by the partially coherent illumination and projected and exposed will be described. The pitches of the periodic patterns 1 and 2 of the mask are also formed of lines and spaces, and the line width L and the space width S are equal to each other. S
Although the pattern, 0.3 pitch, has a 0.15 μmL / S pattern, the present invention is not limited to this.

When the relationship between the interval D between the periodic patterns and the region where the degree of influence of the boundary is examined, the result shown in the graph of FIG. 19 was obtained. The horizontal axis of the two graphs in FIG. 19 indicates the interval between the periodic patterns, and the vertical axis of the two graphs indicates the area affected by the boundary. The area having this influence is defined as the pitch of the design value of 0.24 or 0.3 with respect to the reproducibility of the line width.
The case where there was a change of ± 2.5% or more with respect to μm, or the case where there was a change of ± 2.5% or more with respect to the contrast of the pattern in the central part of the periodic pattern regarding the contrast. Since the degree of influence of the boundary is the largest at the boundary, and gradually decreases as the distance from the boundary increases, it indicates how far the boundary is affected. FIG. 19A shows the degree of influence on the periodic pattern 1 having a boundary of 0.24 pitch.
(B) shows the degree of influence on the periodic pattern 2 of 0.3 pitch.

From FIG. 19, when the interval D between the periodic patterns is set to infinity, the effect on the 0.24 pitch pattern at the boundary is 0.6 μm, but gradually as the interval between the periodic patterns is reduced. It can be seen that the affected area becomes narrower, and that at the interval of 0.12 μm which is the same as the width S of the space S of the periodic pattern 1 of 0.24 pitch, the influence of the boundary is completely eliminated. Furthermore, the space is defined as the width S
As the size becomes smaller, the area affected by the boundary gradually increases. The same can be said for the influence from the boundary of the periodic pattern 2 of 0.3 pitch.

From FIG. 19, the region where the influence of the boundary between the two periodic patterns is affected changes depending on the interval between the periodic patterns, and one pitch (0.24 μm In other cases, even if the periodic patterns have different pitches,
It can be seen that, as in the first embodiment, the closer the position is within the range of a certain interval, the smaller the influence of the boundary on both periodic patterns.

When the influence on the pitch of the periodic pattern 1 having the pitch of 0.24 μm is minimized, the interval between the periodic patterns is equal to the space S width of the periodic pattern 1 (0.12 μm). In this case, it was 0.12 μm. Also, with respect to the periodic pattern 2 having a pitch of 0.3 μm, its influence on the pitch is minimized because the interval between the periodic patterns is also the same as that of the periodic pattern 2.
Was equal to the space S width (0.15 μm), and in this case, it was 0.15 μm. However, the influence of this boundary is greater when the line width is smaller, so if periodic patterns having different pitches are adjacent to each other, the interval between the periodic patterns is set to 0.12 μm, which is the space width of the periodic pattern having the smaller pitch. It is desirable to match them.

However, it is not always possible to arrange patterns at the most preferable intervals as described above. In such a case, similarly to the first embodiment, a case where the affected area is not used based on FIG. 19 or a case where the influence of the boundary is eliminated by performing pattern correction such as OPC and the boundary is used to the very end. is there. When the affected area is not used, it is necessary to devise a pattern arrangement according to each interval as in the first embodiment.

In the following description, “1P” is the length of one pitch of the periodic pattern, and is the sum of the width of the line L and the width of the space S. Therefore, 2S corresponds to 1P as compared with the first embodiment in which 2P is the length assigned to two pitches of the periodic pattern.

When the interval D between the periodic patterns is set closer to half the width of the space S, the influence of the boundary becomes higher than when the periodic patterns are separated from each other considerably, so that the pattern at the boundary position of one periodic pattern is changed. Pull out one,
It is necessary to increase the interval between periodic patterns. However, the interval between the periodic patterns should not be exactly 1P.

It is particularly necessary to pay attention to the case where periodic patterns are arranged next to each other at the interval of 1P.
This is because the enhancement of the light intensity of the pattern at the boundary position is most remarkable in the case of 1P, and both the contrast and the line width difference change more greatly than in the case of the isolation. When the interval between the periodic patterns is 1P, one pattern at the boundary position of one of the periodic patterns is removed, and the intervals between the periodic patterns are arranged to be 2P.

When the interval D between the periodic patterns is larger than 2P, one of the periodic patterns is increased, and the relationship between the line and the space of the periodic pattern is 0.5L ≦ D ≦ S + 0 when L <S. 0.5L ≦ 5L, S ≦ L ≦ S
Adjust so that D ≦ 1L + 0.5S.

Further, when the above-described light transmission type mask is used, when the relationship between the line and the space is L <S, (S +
0.5L) to 1P, (1L + 0.5) when S ≦ L
In the case of S) to 1P, there is a possibility that the pattern light intensity at the boundary position may be emphasized, and the pattern arrangement may be changed at the time of double exposure, the illumination conditions in the double exposure, and the light amount ratio at the time of exposure Must be set so that the light intensity of the pattern at the boundary position is not too strong.

In summary, when adjacent periodic patterns having different pitches and opposite patterns at the boundary position are adjacent to each other, the interval D between the periodic patterns is equal to the space width S of one of the periodic patterns. When such an arrangement is not possible, the relationship between the line and the space is defined as follows: When L <S, the line width is L, 0.5L ≦ D ≦ 1S + 0.5L, and S ≦ L Is 0.5
It is necessary to adjust S ≦ D ≦ 1L + 0.5S.

If the interval D between the periodic patterns is 0.5S or less, one of the patterns at the boundary position of one of the periodic patterns is eliminated, and the interval between the two is increased. When the interval D between the periodic patterns is 1P, one pattern at the boundary position of one of the periodic patterns is eliminated, and the patterns are arranged at an interval of 2P. Further, the interval D between the periodic patterns is 1
If it is wider than P, the pattern at the boundary position of one of the periodic patterns is increased to extend the periodic pattern. When the relationship between the line and the space is L <S, 0.5L ≦ D ≦ S + 0.
When 5L and S ≦ L, the adjustment is performed so that 0.5S ≦ D ≦ L + 0.5S. In the case of the above-mentioned light transmission type pattern,
When L <S, the interval D between the periodic patterns is (S + 0.5
L) to 1P, when the distance D between the periodic patterns is (1L−0.5S) to 1P when S ≦ L, consideration should be given to the light amount ratio and illumination conditions when performing double exposure. What is necessary is the same as in the first embodiment.

A detailed description of the case of performing pattern correction such as OPC to eliminate the influence of the boundary and use it to the very end of the boundary is omitted. However, the pitch correction method is described below. There are cases where the overall pitch is not changed, and cases where the line space is adjusted. This correction may be performed using either a periodic pattern or a normal exposure pattern.

The features of the mask described above are as follows.

(A-1) In a mask having a periodic pattern used for an exposure method for performing a double exposure of a normal exposure and a periodic pattern exposure on a substrate to be exposed, two periods in which one pitch is composed of lines and spaces When patterns are adjacent to each other in the periodic direction, the patterns at those boundary positions are lines having phases opposite to each other.

(A-2) In the case where two periodic patterns each composed of a line and a space are adjacent to each other in the periodic direction, the interval between the two periodic patterns is determined by the space width S of either periodic pattern. Equal to.

(A-3) In the case where two periodic patterns in which one pitch is composed of a line and a space are adjacent to each other in the periodic direction, when the interval D between the periodic patterns is 0.5S or less, which cycle One line at the boundary position of the pattern is removed to widen the interval between the periodic patterns (S is the width of the space of either periodic pattern).

(A-4) In the case where two periodic patterns each composed of a line and a space are adjacent to each other in the periodic direction, one of the two periodic patterns is used when the interval between the periodic patterns is the same as that of the other. One pattern (line) at the boundary position of the periodic pattern of
The interval D between the periodic patterns is set to 2P.

(A-5) When two periodic patterns, each of which consists of a line and a space, are adjacent to each other in the periodic direction, one of the periodic patterns has a larger interval than the other. The pattern at the boundary position of the periodic pattern is added to extend the periodic pattern, and the interval D between the periodic patterns is 0.5S ≦ D ≦ L +
0.5S (S is the width of the space of the periodic pattern, L is the width of the line of the periodic pattern).

(A-6) In the case where two periodic patterns in which one pitch is composed of a line and a space are adjacent to each other in the periodic direction, the two patterns are light-transmitting patterns. Interval D is L + 0.5
In the case of S ≦ D ≦ P, one line at the boundary position of one of the periodic patterns is removed to increase the interval D between the periodic patterns (S is the width of the space of the periodic pattern, L is the width of the line of the periodic pattern) , P is S + L).

(A-7) The above concept can be applied to the case where the pitches of the two adjacent periodic patterns and the lines and spaces constituting the pitches are equal to or different from each other.

(A-8) When double exposure of normal exposure and periodic pattern exposure is performed on a substrate to be exposed, if there are two periodic patterns adjacent in the periodic direction in the periodic pattern exposure, a boundary between the two patterns is obtained. If a nearby pattern is affected by the boundary, that pattern should not be used in pattern formation by double exposure.

(A-9) When double exposure of normal exposure and periodic pattern exposure is performed on the substrate to be exposed, if there are two periodic patterns adjacent in the periodic direction in the periodic pattern exposure, the two periodic patterns are exposed. In the case where a pattern area affected by this boundary is used for pattern formation by double exposure near the boundary of
Apply C.

FIG. 20 is a schematic view showing a high-resolution exposure apparatus capable of performing both periodic pattern exposure by two-beam interference exposure and normal exposure. The exposure apparatus can select an exposure mode in which the above-described multiple exposure is performed by these exposures or an exposure mode in which only the normal exposure (one time) is performed. Then, in the multiple exposure mode, periodic pattern exposure is performed using the mask (reticle) described above.

In FIG. 20, reference numeral 221 denotes a KrF excimer laser or an ArF excimer laser, both of which have a wavelength of 2;
Emit exposure light of 50 mm or less. 222 is an illumination optical system, 2
23 is a mask (reticle), 224 is a mask stage,
Reference numeral 227 denotes a projection optical system for reducing and projecting the circuit pattern of the mask 223 onto the wafer 228. Reference numeral 225 denotes a mask (reticle) changer. The stage 224 selects one of a normal reticle and the above-described Levenson phase shift mask (reticle). It is provided for the purpose of supply.

In order to make the mask stage parallel to the longitudinal direction of the fine pattern of the reticle in the normal exposure and the longitudinal direction of each pattern of the periodic pattern of the reticle in the periodic pattern exposure, the mask stage is previously drawn with a bar code or the like on the mask. It has a function to rotate the mask based on certain information.

Reference numeral 229 in FIG. 20 denotes one XYZ stage shared by the periodic pattern exposure and the normal pattern exposure. The stage 229 is movable in a plane orthogonal to the optical axis of the optical system 227 and in the optical axis direction. The position in the XY directions is accurately controlled using a laser interferometer or the like.

The apparatus shown in FIG. 20 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 exposure apparatus shown in FIG. 20 has a coherency of partial coherent illumination: the value of σ (sigma) is variable (for the partial coherent illumination of small σ of about σ = 0.2 described above). In this case, the above-described illumination light (1a) or (1b) in the block 230 is supplied to the Levenson-type phase shift reticle, and the block is used in the case of large partial coherent illumination during normal exposure. 2
The illumination light (2a) shown in FIG. 30 is supplied to a desired reticle. Switching from the large σ to the small σ partial coherent is performed by changing the aperture stop for the large σ, which is usually placed immediately after the fly-eye rains of the optical system 222, to a small σ having an aperture diameter sufficiently smaller than this stop. It can be replaced with an aperture stop.

Note that “partial coherent illumination” is σ
= (Reticle-side numerical aperture of illumination optical system / reticle-side numerical aperture of projection optical system).

In partial coherent illumination in periodic pattern exposure, σ is set to 0.3 or less. Partial coherent illumination when performing normal exposure has σ of 0.6 or more, especially σ =
0.8 is desirable. Furthermore, it is still more effective to illuminate the reticle with the annular illumination system in which the illuminance distribution of the illumination light immediately after the fly-eye lens is lower on the inside than on the outside in the normal exposure.

Manufacturing of various devices such as semiconductor chips such as ICs and LSIs, display elements such as liquid crystal panels, detection elements such as magnetic heads, and image pickup elements such as CCDs using the mask described above, the exposure method and the exposure apparatus. Is possible.

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

FIG. 21 shows a flow of manufacturing a semiconductor device (a semiconductor chip such as an IC or LSI, or a liquid crystal panel or a CCD).

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

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

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

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

FIG. 22 shows a detailed flow of the wafer process. Step 11 (oxidation) oxidizes the wafer's surface. Step 12 (CVD) forms an insulating film on the wafer surface.

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

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

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

[0138]

According to the present invention, even when a mask in which a plurality of periodic patterns are adjacent to each other is used for multiple exposure,
A good pattern image as designed is obtained on the wafer.

[Brief description of the drawings]

FIG. 1 is a flowchart of an exposure method according to the present invention.

FIG. 2 is an explanatory view showing an exposure pattern by two-beam interference exposure.

FIG. 3 is an explanatory diagram showing exposure sensitivity characteristics of a resist.

FIG. 4 is an explanatory view showing pattern formation by development.

FIG. 5 is an explanatory view showing an exposure pattern by ordinary two-beam interference exposure.

FIG. 6 is an explanatory view showing an exposure pattern by two-beam interference exposure in the present invention.

FIG. 7 is an explanatory view showing an example of an exposure pattern (lithography pattern) that can be formed in the present invention.

FIG. 8 is an explanatory view showing another example of an exposure pattern (lithography pattern) that can be formed in the present invention.

FIG. 9 is an explanatory view showing another example of an exposure pattern (lithography pattern) that can be formed in the present invention.

FIG. 10 is a schematic diagram of a periodic pattern according to the first embodiment of the present invention.

FIG. 11 is an explanatory diagram of a relationship between a pattern interval and a boundary effect according to the first embodiment of the present invention.

FIG. 12 is an explanatory diagram of a periodic pattern arrangement according to the present invention.

FIG. 13 is an explanatory diagram of a periodic pattern arrangement according to the present invention.

FIG. 14 is an explanatory diagram of a periodic pattern arrangement according to the present invention.

FIG. 15 is an explanatory diagram of a periodic pattern arrangement according to the present invention.

FIG. 16 is an explanatory diagram of a one-dimensional intensity distribution of a periodic pattern image according to the present invention.

FIG. 17 is an explanatory diagram of a line width deviation from a pattern interval and a design value.

FIG. 18 is a schematic diagram of a periodic pattern according to the second embodiment of the present invention.

FIG. 19 is an explanatory diagram of a relationship between an interval and a boundary effect in patterns of different pitches according to the present invention.

FIG. 20 is a schematic view of a main part of the exposure apparatus of the present invention.

FIG. 21 is a flowchart of a device manufacturing method according to the present invention.

FIG. 22 is a flowchart of a device manufacturing method according to the present invention.

FIG. 23 is an explanatory view of a pattern by conventional double exposure.

FIG. 24 is an explanatory diagram of a conventional periodic pattern and its pattern image.

[Explanation of symbols]

 221 Excimer laser 222 Illumination optical system 223 Mask (reticle) 224 Mask (reticle) stage 225 2 Beam interference mask and mask for normal projection exposure 226 Mask (reticle) changer 227 Projection optical system 228 Wafer 229 XYZ stage

Claims (15)

[Claims] 1. When there are a plurality of periodic patterns, and when an interval between lines of one of the periodic patterns is S, the one periodic pattern and another periodic pattern adjacent thereto in the periodic direction A distance D between the mask and the mask is 0.5S <D <1.5S. 2. When there are a plurality of periodic patterns and an interval between lines of one of the periodic patterns is represented by S, the one periodic pattern and another periodic pattern adjacent thereto in the periodic direction. A mask, wherein a distance D from a pattern is 0.9S <D <1.1S. 3. The mask according to claim 1, wherein the phases of the patterns located at the boundaries between the two adjacent periodic patterns are opposite to each other. 4. A mask having a plurality of periodic patterns, wherein a pattern located at a boundary between each of two periodic patterns adjacent in the periodic direction has a phase opposite to each other. 5. An exposure method comprising exposing a photosensitive substrate using the mask according to claim 1. Description: 6. A multiple exposure method including exposure using a mask according to any one of claims 1 to 4 and exposure using another mask. 7. An exposure apparatus having an exposure mode for executing the exposure method according to claim 5. Description: 8. A device manufacturing method, comprising: exposing a wafer with a device pattern by the exposure method according to claim 5; and developing the exposed wafer. 9. A mask having first and second periodic patterns, wherein the first and second periodic patterns are both 1
The pitch is composed of lines and spaces, and the first
Has a pitch P1, a line width L1 and a space width S1, and the second periodic pattern
Pitch is P2, line width is L2, space width is S2
Wherein the pitch P1 and the pitch P2 are different from each other, the first and second periodic patterns are adjacent to each other in a periodic direction, and the distance D between the first and second periodic patterns is
Indicates that one of the space widths S1 and S2 is S,
When one of the line widths L1 and L2 is L, 0.5L ≦ D ≦ S + 0.5L is satisfied when L <S, and 0.5S ≦ D ≦ L + 0.5S when S ≦ L. A mask characterized by satisfying the following. 10. A mask having first and second periodic patterns, wherein each of the first and second periodic patterns has a pitch of one line and a space, and the first periodic pattern The pattern has a pitch of P1, a line width of L1,
The width of the space is S1, the pitch of the second periodic pattern is P2, the width of the line is L2, the width of the space is S2, and the pitch P1 and the pitch P2 are different from each other;
The first and second periodic patterns are adjacent to each other in a periodic direction, and a distance D between the first and second periodic patterns is equal to the width S1 of the space and the width S2 of the space. mask. 11. A mask having a plurality of periodic patterns, wherein each of the periodic patterns has a pitch of a line and a space, and two pitches adjacent to each other in the periodic direction and having the same pitch and the same line width. When the width D of the line is L and the width of the space is S, D = S
When L <S, 0.5L ≦ D <S or S <D ≦ S + 0.5L is satisfied, and when S ≦ L, 0.5 is satisfied.
A mask characterized by satisfying S ≦ D <L or S <D ≦ L + 0.5S. 12. An exposure method for exposing a photosensitive substrate using the mask according to any one of claims 9 to 11. 13. A multiple exposure method including exposure using a mask according to any one of claims 9 to 11 and exposure using another mask. 14. An exposure apparatus having an exposure mode for executing the exposure method according to claim 12. 15. A device manufacturing method, comprising: exposing a wafer with a device pattern by the exposure method according to claim 12; and developing the exposed wafer.