JPH11354411A - Method for evaluating aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for evaluating aligner by which the comatic abberation of a lens used in an exposing device can be measured easily with high accuracy. SOLUTION: Firstly, the relation between the comatic abberation of a lens used in an exposing device and the dimensional difference between opening patterns formed by the light rays transmitted through two opening sections is found in advance. Then, a mask for evaluation is installed to an aligner to be evaluated and the surface of a substrate on which a photosensitive resin film is formed is exposed by using the aligner. Then the opening patterns formed of the light rays transmitted through the two openings are obtained by developing the photosensitive resin film on the surface of the resin. After obtaining the opening patterns, the dimensional difference between the two opening patterns is calculated by measuring the widths of the patterns. Thereafter, the comatic abberation of the lens (optical system) is found from the actually measured dimensional difference based on the previously found relation between the comatic abberation and dimensional difference.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of evaluating an exposure apparatus used in an optical lithography process in a semiconductor device manufacturing process, and more particularly, to an evaluation of an exposure apparatus capable of measuring a coma aberration of the exposure apparatus with high accuracy. About the method.

[0002]

2. Description of the Related Art Conventionally, a phase shift mask has been developed for the purpose of extending the limit of optical lithography. A phase shift mask means that a phase of a part of light transmitted through a mask (mask reflected light in a reflective mask) is shifted by 180
マ ス ク A mask to change.

FIG. 15 is a sectional view showing a Shibuya-Levenson type phase shift mask. Note that the Shibuya-Levenson method is the name of the inventor, and the Alternating Phase Shift
Also called Mask. As shown in FIG. 15, a light-shielding film 22 made of a light-shielding material such as chromium is selectively formed on one surface of a transparent substrate 21 made of synthetic quartz or the like.
The transparent regions 23a and the light shielding regions 23b are formed alternately. In the region covering one transparent region 23a of the transparent adjacent regions 23a, CVD SiO _2, sputtering SiO ₂ or SOG (Spin On Glass) made of transparent film 2
4 are formed. When the refractive index of the exposure light having the wavelength λ with respect to the transparent film 24 is n, the transparent film 24
Is set to t = λ / {2 (n−1)}.

In the phase shift mask configured as described above, the transmission light passing through the area where the transparent film 24 is formed and the transmission light passing through the area where the transparent film 24 is not formed are 180 degrees apart. A phase difference of ゜ is generated. Therefore, the adjacent transmitted lights having phases different from each other by 180 ° interfere with each other, so that the contrast of the mask transfer image can be improved. As described above, the phase shift mask is effective for improving the resolution and the depth of focus. However, the phase shift mask is extremely susceptible to the aberration of the projection lens. It is known that a pattern is deformed asymmetrically due to aberration. Therefore, recently, it is necessary to accurately measure and manage aberrations of an exposure apparatus, particularly, coma.

Incidentally, the aberration of the lens is completely adjusted in the production line of the device maker. And even after installing the exposure apparatus on the semiconductor device manufacturing line, the aberration of the lens has been confirmed again, and if an abnormality is confirmed,
Tweaked on the fly.

As a method of measuring coma aberration, there is disclosed a method capable of easily measuring coma aberration of a projection lens with good reproducibility (Japanese Patent Laid-Open No. Hei 5-118957). This measuring method is a method for directly measuring the intensity distribution of the aerial image of a desired reticle pattern obtained through a projection lens. That is, in the transfer image of the aperture pattern, when the vibration of light converges to 0 in the amplitude distribution, the light peaks through 0 and converges while vibrating in the negative (opposite phase) and positive directions, so that the main peak Sub-peaks occur on the left and right of Then, in the light intensity distribution transmitted through the opening (transparent region) extending in the predetermined direction (Y direction), if coma exists in the X direction orthogonal to the Y direction,
The left and right sub-peaks have different heights. Therefore, the coma aberration can be obtained by measuring the difference (intensity difference) between the heights of the sub-peaks.

In addition, a coma aberration measuring method using a halftone phase mask has been disclosed (JP-A-9-257).
646). In a halftone phase mask having a transmission intensity of T, the amplitude of light on the image plane becomes -ΔT in the halftone portion, and the overshoot also oscillates around this -ΔT. Therefore, in the first overshoot portion adjacent to the main pattern, the value of the light intensity does not decrease, and a subpeak called a side lobe is generated. Then, since a large intensity difference occurs in the side lobe due to the coma aberration, the coma aberration can be obtained by measuring the intensity difference.

[0008]

However, in the method described in Japanese Patent Application Laid-Open No. 5-118957,
Since the sub-peaks generated on the left and right of the main peak vibrate based on 0, the light intensity given by the square of the vibration has an extremely small value. Therefore, even if the coma aberration is obtained based on the difference in light intensity, the measurement error increases.

Further, when the method described in Japanese Patent Application Laid-Open No. 9-257646 is used, it is possible to obtain the coma aberration with higher precision than when a normal mask is used. Measurement accuracy cannot be satisfied.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to provide an exposure apparatus evaluation method capable of easily measuring a coma aberration in an exposure apparatus with high accuracy.

[0011]

According to the present invention, there is provided a method for evaluating an exposure apparatus, comprising: a first exposure light; and a second exposure light having a phase difference of 180 ° with respect to the first exposure light. Light and
Irradiating the photosensitive resin film formed on the surface of the test plate via the optical system of the exposure device, and developing the photosensitive resin film to expose a first pattern exposed by the first exposure light; Obtaining a second pattern exposed by the second exposure light and formed in a predetermined direction apart from the first pattern; and a step of obtaining a width of the first pattern in the predetermined direction and the second pattern. Measuring a difference from the width in the predetermined direction, and obtaining a coma aberration of the optical system based on the difference.

[0012] The first and second exposure lights are provided on a transparent substrate, a light shielding film formed on the transparent substrate, a first opening selectively provided in the light shielding film, and a second light source. It can be obtained by transmitting incident light through a phase shift mask having an opening and a transparent film covering one of the first opening and the second opening. Preferably, the incident light is transmitted in a direction orthogonal to the phase shift mask.

Further, the first and second exposure lights are provided with a transparent substrate, a light shielding film formed on the transparent substrate, and a first opening selectively provided in the light shielding film. The oblique incident light may be obtained by transmitting oblique incident light through a mask having two openings, and the oblique incident light is preferably emitted from annular illumination.

Another method for evaluating an exposure apparatus according to the present invention is as follows.
Three or more exposure lights are arranged, and the phases of adjacent exposure lights are different from each other by 180 °, and the outermost first light is located.
Irradiating an exposure light group in which the exposure light and the second exposure light have the same phase to a photosensitive resin film formed on the surface of the test plate via an optical system of an exposure apparatus; Developing a photosensitive resin film to expose a first pattern exposed by the first exposure light and a first pattern exposed by the second exposure light;
Obtaining a second pattern formed apart from the pattern in a predetermined direction, and measuring a difference between a width of the first pattern in the predetermined direction and a width of the second pattern in the predetermined direction, Obtaining a coma aberration of the optical system based on the difference.

In the first invention of the present invention, one
The photosensitive resin film is irradiated with the first exposure light and the second exposure light having phases different from each other by 80 ° through the optical system of the exposure apparatus, and is developed to thereby form the first pattern and the second pattern.
To get the pattern. Then, a dimensional difference (actually measured value) of the width of the first pattern and the second pattern is measured, and based on a relationship between a previously obtained coma aberration and the dimensional difference (theoretical value),
The coma of the optical system is obtained from the actually measured dimensional difference.

As described above, when the photosensitive resin film is exposed using a set of exposure light having phases different by 180 °,
Since the difference in light intensity is greater than when one set of exposure light having the same phase is used, the dimensional difference in the resulting pattern width is about twice. That is, even when a small coma exists, a dimensional difference in the pattern width appears remarkably. Therefore, by obtaining the coma aberration based on the actually measured dimensional difference, extremely high measurement accuracy can be obtained as compared with the case where one set of exposure light having the same phase is used.

In the case where three or more exposure light beams are arranged, if the phase difference between adjacent exposure light beams deviates from 180 °, the focal position changes and the exposure light beam is formed on the photosensitive resin film. Since a dimensional difference occurs between the adjacent patterns, an error occurs in the coma aberration obtained based on the dimensional difference. However, in the second invention of the present invention, of the three or more exposure lights, the outermost exposure light has the same phase, and the first and second patterns exposed by the outermost exposure light have the same phase. The coma aberration is obtained based on the dimensional difference.
This makes it possible to prevent the phase error from affecting the coma aberration, and it is possible to easily obtain the coma aberration with high accuracy as in the first invention.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for evaluating an exposure apparatus according to an embodiment of the present invention will be specifically described below with reference to the accompanying drawings. FIG. 1A is a plan view showing a part of a coma aberration measuring mask used in the method for evaluating an exposure apparatus according to the first embodiment of the present invention, and FIG.
It is sectional drawing of the direction which follows the AA of (a). However, in FIG. 1A, the surface on which the transparent film or the like is formed is illustrated as an upper surface.

As shown in FIGS. 1 (a) and 1 (b),
A light-shielding film 2 is formed on one surface of a transparent substrate 1. The light shielding film 2 is provided with two openings 2a and 2b extending in a direction (Y direction) from one end surface of the transparent substrate 1 to the opposite end surface. In a region covering one opening 2b, a transparent film 3 made of SOG (Silicon On Glass) is formed as a phase shifter. Thus, the Shibuya-Levenson type phase shift mask 4 is configured.

In this embodiment, the widths of the openings 2a and 2b and the width of the light shielding film 2 between the adjacent openings 2a and 2b are 1.25 μm. Therefore, in an exposure apparatus having a reduction ratio of 5 times,
Each becomes 0.25 μm on the imaging plane. In addition, SOG for KrF excimer laser light (wavelength λ: 248 nm)
Since the refractive index n of the film is 1.48, the wavelength λ and the SOG
When the film thickness t of the SOG film is calculated by substituting the refractive index n of the film into the equation t = λ / {2 (n−1)}, t = 248 / ｛2
(1.48-1)｝ = 258. Therefore, by setting the thickness of the SOG film (transparent film 3) to 258 nm, a phase difference of 180 ° is generated between the transmitted light transmitted through the opening 2a and the transmitted light transmitted through the opening 2b. I have.

Next, a method for evaluating an exposure apparatus according to the first embodiment of the present invention will be described. First, the relationship between the coma aberration and the dimensional difference of the opening pattern obtained by exposure with the transmitted light transmitted through the openings 2a and 2b of the mask 4 shown in FIG. This size difference is to use the-threshold model (Threshold model), i.e., the photosensitive resin layer of light having a predetermined light intensity I _th or more intensity is irradiated region is eluted by development,
It can be obtained from a simulation result of a light intensity distribution transmitted through the Shibuya-Levenson type phase shift mask 4 on the condition that the photosensitive resin film in a region irradiated with light having an intensity less than the light intensity I _th remains. .

The relationship between the coma and the dimensional difference is as follows, for example. FIG. 2 shows the dimensional difference between the widths of adjacent opening patterns formed on the photosensitive resin film on the vertical axis (the width of the opening pattern obtained by light passing through the opening 2b−the opening pattern obtained by light passing through the opening 2a). Is a graph showing the relationship between the dimensional difference and the coma aberration by taking the X-direction coma aberration obtained by the light intensity distribution simulation on the horizontal axis. In FIG. 2, the solid line 5 shows the relationship between the coma aberration and the dimensional difference obtained when the Shibuya-Levenson type phase shift mask 4 is used, and the broken line 6 uses a normal mask having two openings. The relationship between the coma aberration and the dimensional difference obtained in this case is shown.
Further, as the light intensity I _th of the threshold model,
The light intensity is set so that the width of the aperture pattern becomes 0.25 μm as designed when the coma aberration is 0.

Next, the mask for evaluation is set on an exposure apparatus to be evaluated, and the surface of the substrate having the photosensitive resin film formed on the surface is exposed using the exposure apparatus. However, FIG.
When the mask shown in FIG. 1A and FIG. 1B is used, coma in only the X direction perpendicular to the direction (Y direction) in which the openings 2a and 2b extend is measured. However, in the evaluation of the exposure apparatus, it is necessary to measure the aberrations in the X direction and the Y direction at the same position in the exposure area. Therefore, as the evaluation mask, a set of measurement patterns including two openings extending in the Y direction and two openings extending in the X direction has a thickness of 10 nm at a desired position (aberration measurement location).
Use a mask provided with dimensional accuracy of

Thereafter, by developing the photosensitive resin film on the surface of the substrate, a Y-direction opening pattern formed by light transmitted through the opening extending in the Y direction of the mask and an opening extending in the X direction of the mask are formed. An X-direction opening pattern formed by the transmitted light is obtained. Thereafter, the width (length in the X direction) of two patterns adjacent in the X direction is measured for the obtained Y direction opening pattern, the dimensional difference is calculated, and the X direction pattern is adjacent in the Y direction. 2
The width (length in the Y direction) of the book pattern is measured, and the dimensional difference is calculated.

Then, as shown in FIG. 2, the coma aberration of the lens (optical system) is obtained from the actually measured dimensional difference based on the relationship between the previously obtained coma aberration and the dimensional difference. In this manner, coma aberration can be measured for each point of the exposure area by the exposure apparatus to be evaluated.

For example, when measuring coma aberration at each position of an exposure area having one side of 22 mm, 2 mm
If measured at intervals, 11 × 11 = 121 (locations)
It is necessary to measure the measurement point in two directions of the X direction and the Y direction by a scanning electron microscope (SEM). Therefore, conventionally, an extremely large number of steps were required to measure the coma aberration. However, recently, a CD-SE used for dimensional control in a semiconductor manufacturing line has been used.
According to M, an image of an alignment mark and a measurement pattern on a semiconductor substrate is recorded, and data can be automatically collected for all measurement points without an attendant. Therefore, as shown in this embodiment, the exposure apparatus can be evaluated very easily by using the method for measuring the dimensions of the actually developed opening pattern.

As shown in FIG. 2, when the relationship between the dimensional difference and the coma aberration is obtained by using a Shibuya-Levenson type phase shift mask, it is about 2 times larger than when a normal mask is used. Double dimensional differences can be obtained. In other words, when the coma aberration is 0.10λ, when the Shibuya-Levenson type phase shift mask is used, the dimensional difference of the obtained opening pattern width is 0.045 μm, whereas when the ordinary mask is used. The dimensional difference (absolute value) of the opening pattern width is about 0.02 μm. In this embodiment, since the coma aberration is obtained from the dimensional difference using the Shibuya-Levenson type phase shift mask, it is possible to obtain the aberration with higher accuracy as compared with the case where a normal mask is used. .

The reason why coma aberration can be obtained with higher accuracy when a phase shift mask is used than when a normal mask is used will be described in more detail below. FIG. 3A is a cross-sectional view illustrating a mask having one opening, and FIG. 3B is a graph in which the vertical axis represents the amplitude of light transmitted through the mask having one opening, and the horizontal axis represents the amplitude. It is a graph which shows the relationship between the amplitude of light and a position taking a position. FIG. 4A is a cross-sectional view showing a mask having two openings, and FIG. 4B shows the amplitude of light transmitted through the mask having two openings on the vertical axis, and shows the horizontal axis. It is a graph which shows the relationship between the amplitude of light and a position, taking a position on an axis. FIG. 5A is a sectional view showing a Shibuya-Levenson type phase shift mask, and FIG. 5B is a vertical axis showing an amplitude of light transmitted through the Shibuya-Levenson type phase shift mask, and a horizontal axis. It is a graph which shows the relationship between the amplitude of light and a position taking a position.

As shown in FIGS. 3A and 3B,
When a light-shielding film 32 is formed on one surface of a transparent substrate 31 and a mask 34a in which one opening 32a extending in a predetermined direction (Y direction) is formed in the light-shielding film 32 is used, Y
When the coma exists in the X direction orthogonal to the direction, the amplitude overshoots on both sides of the opening 32a extending in the Y direction are different from each other. However, the overshoot of this amplitude is close to zero, and the light intensity represented by the square thereof is extremely small. When the mask shown in FIG. 3A is used, the opening 32a
The amplitude at the left and right overshoots of-
a, When -b, a difference [Delta] I _a light intensity in the left and right sides of the opening 32a is represented by Equation 1 below.

[0030]

## EQU1 ## ΔI _a = b ² −a ²

FIG. 4 (a) and FIG. 4 (b)
As described above, two openings 32b extending in the Y direction are formed in the light shielding film 32.
And a mask 34b provided with 32c is used.
Is that the overshoot of one opening 32b is
It overlaps the main peak of the opening 32c, and the other opening
The overshoot at 32c is caused by the opening 32b.
Overlap with the peak of the Therefore, the size of the main peak
Let c be the overshoot on the left and right of the opening.
From the difference, the light transmitted through the opening 32b and the opening 32
When the light intensity difference from the light transmitted through c is calculated,
Light intensity difference ΔI _bIs represented by Equation 2 below.

[0032]

ΔI _b = (ca) ² − (c−b) ² = 2 (ba) c + a ² −b ² = (ab) (2ca−ab)

On the other hand, as shown in FIGS. 5A and 5B, a light-shielding film 2 having two openings 2a and 2b extending in the Y direction is formed on one surface of a transparent substrate 1. When the Shibuya-Levenson type phase shift mask 4 in which the transparent film 3 is formed in the area covering the opening 2b is used, the light transmitted through the transparent substrate 1 and the transparent film 3 through the opening 2b is
The phase of light transmitted through only the transparent substrate 1 through the opening 2a is inverted by 180 °. Therefore, the opening 2a
After calculating the light intensity difference between the light transmitted through the light and opening 2b which transmits through the difference [Delta] I _c of the light intensity is represented by the following equation 3.

[0034]

ΔI _c = (c + b) ² − (c + a) ² = 2 (ba) c + b ² −a ² = (ba) (2c + a + b)

As shown in the above formulas (1) to (3), it is shown that when the Shibuya-Levenson type phase shift mask is used, the light intensity difference becomes larger than when a normal mask is used.

Next, with respect to the mask 34b having two openings shown in FIG. 4A and the Shibuya-Levenson type phase shift mask 4 shown in FIG. A description will be given of a case in which the intensity of is simulated. 6 and 7 are graphs showing the relationship between the light intensity and the position with the relative light intensity on the vertical axis and the position on the horizontal axis. FIG. 6 shows a mask 3 having two openings.
7 shows the case where the Shibuya-Levenson type phase shift mask 4 is used, and the width of each of the two openings is 0.25 μm on the image plane. 6 and 7, the position of 0 nm on the horizontal axis corresponds to the center of the two openings provided in the light-shielding film of the mask, and the relative light intensity on the vertical axis passes through a sufficiently large transparent region. This is a value normalized by setting the light intensity to 1. In the figure, the solid line 7 indicates 1 when the coma of the lens is 0λ.
The dashed line 8 indicates the case where the coma is set to 0.05λ, and the broken line 9 indicates the case where the coma is set to 0.1λ.

As shown in FIGS. 6 and 7, when any of the masks is used, there is a difference in the intensity of light transmitted through the two openings due to coma aberration.
In particular, when a Shibuya-Levenson type phase shift mask is used, the change in light intensity distribution due to coma aberration is large.

As described above, when the Shibuya-Levenson type phase shift mask is used, a 2
Since the intensity difference of the light transmitted through the openings becomes large, as shown in FIG. 2, the two openings obtained by irradiating the photosensitive resin film on the substrate with the transmitted light and developing the same. The difference in pattern width is larger than that of a normal mask. Therefore, based on the relationship between the dimensional difference and the coma aberration shown in FIG. 2, the present embodiment obtains the coma aberration of the lens from the dimensional difference between the two aperture pattern widths obtained using the Shibuya-Levenson type phase shift mask. In the example method, coma aberration can be obtained with higher accuracy than when a normal mask is used.

For example, in the CD-SEM measurement, if there is a 5 nm error in the dimensional difference between the two opening pattern widths,
When a normal mask is used, a dimensional difference of 5 nm corresponds to a coma aberration of 0.026λ, but when a Shibuya-Levenson type phase shift mask is used, a dimensional difference of 5 nm is 0.011λ. It corresponds to aberration. this is,
This example shows that even when a measurement error of 5 nm occurs, the deviation of the coma aberration is extremely small.

The structure of the mask used in the present invention is not particularly limited as long as it can provide a set of exposure lights having phases different from each other by 180 °. By the same method as described above, coma can be obtained with high accuracy.

FIG. 8A is a plan view showing a part of a coma aberration measuring mask used in the method for evaluating an exposure apparatus according to the second embodiment of the present invention, and FIG. 8
It is sectional drawing of the direction which meets the BB line of (a). However, in FIG. 8A, the surface on which the transparent film or the like is formed is shown as the upper surface.

As shown in FIGS. 8A and 8B,
A light-shielding film 12 is formed on one surface of a transparent substrate 11.
The light-shielding film 12 has three openings 12 extending in a direction (Y direction) from one end surface of the transparent substrate 11 to the opposite end surface.
a, 12b and 12c are provided. In a region covering the central opening 12b, a transparent film 13 is formed as a phase shifter.

Even when the Shibuya-Levenson type phase shift mask 14 configured as described above is used, the coma of the lens can be obtained in the same manner as in the first embodiment.
However, when a phase shift mask having three or more openings is used, if the phase difference deviates from 180 °, the focal position changes and a dimensional difference between adjacent opening patterns having different phases occurs. I do. Therefore, when a phase error occurs, a dimensional difference occurs between the opening having a phase difference of 0 ° and the opening having a phase difference of 180 °, and thus an error occurs in the coma aberration obtained based on the dimensional difference. Will happen.

Therefore, in the second embodiment, the light transmitted through the two outermost openings provided in the light-shielding film on the mask has the same phase, and is transmitted through these two openings. The coma aberration is obtained based on the dimensional difference of the aperture pattern width obtained by the light. This makes it possible to prevent the phase error from affecting the coma aberration, and it is possible to easily obtain the coma aberration with high accuracy as in the first embodiment. Even in the case where a mask having more than three openings is used, similarly, the light transmitted through the two outermost openings is set to the same phase, and the two outermost openings are similarly set. By measuring the dimensional difference in the width of the opening pattern obtained by the light transmitted through the lens, the coma aberration can be obtained with high accuracy.

It should be noted that the finer the pattern size, the more
The dimensional difference in the width of the opening pattern obtained by the light transmitted through the two openings increases. Therefore, it is theoretically preferable to use a mask that can obtain an aperture pattern having a width of about 0.13 μm in dimensions close to the resolution limit on the image plane, that is, in the Shibuya-Levenson type phase shift mask. . However, if the aperture pattern is close to the resolution limit, the shape of the photosensitive resin film is deteriorated, and the edge roughness is deteriorated and the tailing phenomenon occurs. It is preferable to use a mask that can obtain an opening pattern having a width of 0.5 times.

FIG. 9 is a sectional view showing a method for evaluating an exposure apparatus according to a third embodiment of the present invention. FIG. 10 (a)
FIG. 10B is a plan view showing a part of a coma aberration measuring mask used in the exposure apparatus evaluation method according to the third embodiment of the present invention, and FIG. It is sectional drawing of the direction along a line. However, in FIG. 10A, the surface on which the light-shielding film is formed is shown as an upper surface.

As shown in FIGS. 10A and 10B, a light-shielding film 17 is formed on one surface of a transparent substrate 16. The light-shielding film 17 has two openings 1 extending in a direction (Y direction) from one end face of the transparent substrate 16 to the opposite end face.
7a and 17b are provided.

In the third embodiment, as shown in FIG. 9, instead of a Shibuya-Levenson type phase shift mask, a mask 19 having a light-shielding film 17 provided with two openings is formed obliquely. Incident illumination (off-axis illuminatio
n) Expose the photosensitive resin film under the conditions. As described above, by using the super-resolution technique in which the light 10 is incident from a direction oblique to the direction orthogonal to the mask 19 by oblique incidence illumination, also called deformed illumination, two apertures can be used without using a phase shifter. A phase difference occurs in the light transmitted through the transparent substrate 16 via the portions 17a and 17b. Accordingly, the size between the opening 17a and the opening 17b is optimized according to the condition of the oblique incidence illumination, and the light 10a transmitted through the opening 17a is optimized.
18 between the light and the light 10b transmitted through the opening 17b.
When a phase difference of 0 ° is generated, coma can be obtained with high accuracy, as in the first and second embodiments using the Shibuya-Levenson type phase shift mask.

The incident angle of the incident light (the angle between the direction perpendicular to the mask and the light 10 incident on the mask) is θ
(゜), and if the wavelength of the incident light is λ (μm), Si
The pitch P (μm) between the openings for setting the phase difference between the transmitted light 10a and the transmitted light 10 to 180 ° is given by the following equation (4).
Is represented by

[0050]

## EQU4 ## P = λ / (2 sin θ)

However, when the actual oblique illumination is used, since the incident angle θ of the incident light is not one point but has a certain range, the minimum incident angle is θ _min and the maximum incident angle is θ.
_{Assuming max} , an appropriate pitch P (μm) between the openings provided in the light-shielding film of the mask is represented by the following Expression 5.

[0052]

Λ / (2 sin θ _max ) <P <λ (2 sin θ
_min )

FIGS. 11 to 13 are graphs showing the relationship between relative light intensity and position, with the vertical axis representing relative light intensity and the horizontal axis representing position. However, FIG. 11 to FIG.
The width of each of the openings 17a and 17b is 0.25 μm,
The mask 19 shown in FIG. 10 in which the distance between the openings is 0.25 μm, and the numerical aperture NA corresponding to the ability of the lens to collect light
The figure shows a case where a lens having a value of 0.5 is used. Also, in FIGS. 11 to 13, 0 nm on the horizontal axis is used.
Corresponds to the center between the two openings 17a and 17b. Further, FIG.
FIG. 12 shows a case in which the light corresponding to 0.5 of σ at the center of the light is shielded and σ is 0.3-0. FIG. 13 shows the case where the annular illumination of 75 is used, and FIG. 13 shows the case of using the normal illumination where σ is 0.8. In the figure, the solid line 7 indicates the case where the coma of the lens is 0λ, the one-dot chain line 8 indicates the case where the coma is 0.05λ, and the broken line 9 indicates the case where the coma is 0.1λ. .

In FIG. 14, the vertical axis represents the dimensional difference between the widths of adjacent opening patterns formed in the photosensitive resin film, and the horizontal axis represents the coma aberration obtained by light intensity distribution simulation.
It is a graph which shows the relationship between a dimensional difference and a coma aberration. FIG.
4, a solid line 20a, a chain line 20b, and a broken line 2
0c indicates the relationship between the dimensional difference and the coma under the conditions given in FIGS. 11, 12, and 13, respectively. As shown in FIGS. 11 to 14, the change in the light intensity distribution due to coma increases as the central light-blocking rate is increased using annular illumination. That is, when the exposure is performed by the exposure apparatus using the annular illumination having a higher light blocking rate at the center, the dimensional difference in the opening pattern width of the photosensitive resin film obtained by the coma becomes large. The measurement accuracy in the case of obtaining can be improved.

The method of the present invention can be applied not only to an ultraviolet exposure apparatus but also to an X-ray exposure apparatus of the same size or reduced size.
It can be used as well.

[0056]

As described in detail above, according to the present invention,
Of the set of exposure light having 180 ° different phase or three or more exposure light, the outermost exposure light has the same phase, and all adjacent exposure light
Since the photosensitive resin film is exposed using a different exposure light group by 0 °, the difference in light intensity after passing through the optical system of the exposure apparatus becomes large. Therefore, by obtaining the coma aberration based on the actually measured dimensional difference, extremely high measurement accuracy can be obtained.

[Brief description of the drawings]

FIG. 1A is a plan view showing a part of a coma aberration measurement mask used in an exposure apparatus evaluation method according to a first embodiment of the present invention, and FIG. 1B is a plan view of FIG. It is sectional drawing of the direction which follows the AA line.

FIG. 2 is a graph showing the relationship between the dimensional difference and the coma aberration, with the ordinate indicating the dimensional difference of the aperture pattern width and the abscissa indicating the coma aberration.

FIG. 3A is a cross-sectional view showing a mask having one opening, and FIG. 3B is a relationship between the amplitude of light and the position, with the vertical axis representing amplitude and the horizontal axis representing position. FIG.

FIG. 4A is a cross-sectional view showing a mask having two openings, and FIG. 4B shows the relationship between the amplitude of light and the position with the vertical axis representing amplitude and the horizontal axis representing position. FIG.

5A is a cross-sectional view showing a Shibuya-Levenson type phase shift mask, and FIG. 5B shows the relationship between the amplitude of light and the position by taking the amplitude on the vertical axis and the position on the horizontal axis. FIG.

FIG. 6 is a graph showing the relationship between the light intensity and the position, with the relative light intensity on the vertical axis and the position on the horizontal axis.

FIG. 7 is a graph showing the relationship between the light intensity and the position, with the relative light intensity on the vertical axis and the position on the horizontal axis.

FIG. 8A is a plan view showing a part of a coma aberration measuring mask used in an exposure apparatus evaluation method according to a second embodiment of the present invention, and FIG. 8B is a plan view of FIG. It is sectional drawing of the direction which follows the BB line.

FIG. 9 is a sectional view illustrating a method for evaluating an exposure apparatus according to a third embodiment of the present invention.

FIG. 10A is a plan view showing a part of a coma aberration measuring mask used in the evaluation method of the exposure apparatus according to the third embodiment of the present invention, and FIG. 10B is a plan view of FIG. It is sectional drawing of the direction which follows CC line.

FIG. 11 is a graph showing the relationship between relative light intensity and position, with relative light intensity taken along the vertical axis and position taken along the horizontal axis.

FIG. 12 is a graph showing the relationship between relative light intensity and position, with relative light intensity taken along the vertical axis and position taken along the horizontal axis.

FIG. 13 is a graph showing the relationship between relative light intensity and position, with relative light intensity on the vertical axis and position on the horizontal axis.

FIG. 14 is a graph showing the relationship between the dimensional difference and the coma aberration with the ordinate representing the dimensional difference of the aperture pattern width and the abscissa representing the coma aberration.

FIG. 15 is a sectional view showing a Shibuya-Levenson type phase shift mask.

[Explanation of symbols]

1, 11, 16, 21, 31; transparent substrate 2, 12, 17, 22, 32; light-shielding film 2a, 2b, 12a, 12b, 12c, 17a, 17
b, 32a, 32b, 32c; openings 3, 13, 24; transparent films 4, 14, 19, 34a, 34b; masks 10, 10a, 10b; light 23a; transparent regions 23b;

Claims (6)

[Claims] A first exposure light and a second exposure light having a phase difference of 180 ° with respect to the first exposure light are supplied to a test plate through an optical system of an exposure apparatus. Irradiating the photosensitive resin film formed on the surface, developing the photosensitive resin film, exposing the first pattern exposed by the first exposure light, and exposing the photosensitive resin film by the second exposure light Obtaining a second pattern formed apart from the first pattern in a predetermined direction; and determining a difference between a width of the first pattern in the predetermined direction and a width of the second pattern in the predetermined direction. Measuring the coma aberration of the optical system based on this difference. 2. The method according to claim 1, wherein the first and second exposure lights include a transparent substrate, a light-shielding film formed on the transparent substrate, and a first opening selectively provided in the light-shielding film. 2 is obtained by transmitting incident light through a phase shift mask having an opening and a transparent film covering one of the first opening and the second opening. 2. The method for evaluating an exposure apparatus according to claim 1, wherein 3. The method according to claim 2, wherein the incident light is transmitted in a direction orthogonal to the phase shift mask. 4. The first and second light for exposure include a transparent substrate, a light-shielding film formed on the transparent substrate, a first opening selectively provided in the light-shielding film, and a light-emitting device. 2. The method according to claim 1, wherein the mask is obtained by transmitting obliquely incident light through a mask having two openings. 5. The method according to claim 4, wherein the obliquely incident light is emitted from annular illumination. 6. An arrangement in which three or more exposure lights are arranged, the phases of adjacent exposure lights are different from each other by 180 °, and the outermost first exposure light and the second exposure light have the same phase. Irradiating the photosensitive resin group formed on the surface of the test plate with the exposure light group through the optical system of the exposure apparatus; and developing the photosensitive resin film to form the first exposure light. Obtaining a first pattern exposed by a second pattern and a second pattern exposed by the second exposure light and separated from the first pattern in a predetermined direction; and obtaining the predetermined pattern of the first pattern. Measuring a difference between a width in a direction and a width of the second pattern in the predetermined direction, and calculating a coma aberration of the optical system based on the difference. .