JP2002303967A - Mask for exposure, method for producing the same and exposure method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mask for exposure which satisfies conditions of amplitude transmittance and phase contrast with a single layer film and can show its phase shift effect to the fullest extent because the deterioration of image quality at edge parts of a phase shift pattern can be more effectively suppressed as compared with the existing light shielding masks. SOLUTION: A translucent film whose refractive index and extinction coefficient satisfy a desired condition is formed by sputtering on a quarts substrate. An electron beam negative resist is applied on the substrate, an electrically conductive resin film is further formed and pattern formation with electron beams and development are carried out to form a resist pattern. Chemical ion etching is then carried out with gaseous CF4 through the resist pattern as a mask to remove the disclosed translucent film. The resist is removed with a mixed solution of sulfuric acid and a hydrogen peroxide solution to form the objective translucent film mask.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an exposure mask used in a lithography process of a semiconductor manufacturing apparatus, and more particularly to a method for forming a phase shifter made of a translucent film in a lithography mask.

[0002]

2. Description of the Related Art Along with the advance of semiconductor technology, semiconductor devices and semiconductor devices are becoming more highly integrated and finer. In manufacturing this semiconductor device, lithography technology is particularly important as a key to processing.

In the current lithography technique, a method of projecting and exposing a mask pattern onto an LSI substrate via a reduction optical system is mainly used. The miniaturization in this lithography technique is greatly restricted by the exposure wavelength, and it is very difficult to form a pattern having a wavelength equal to or less than the wavelength. This is because in a pattern having the same size as the wavelength, interference occurs in an adjacent pattern, the light intensity is in a region that is originally desired to be formed as a dark portion, and the light amount difference between the dark portion and the bright portion hardly occurs. Therefore, when a pattern is formed on an LSI substrate using an arbitrary wavelength, the minimum line width has to be reduced to a size of about 1.4 times the wavelength.

[0004] However, the minimum line width required for recent LSIs is 0.35 μm for 64 MDRAM and 256 MDRA.
M is 0.25 μm. In order to realize these dimensions by the conventional lithography technology, a minimum line width of 0.1 mm is required.
For 35 μm, it is necessary to cope with the exposure light source using a KrF laser, and for the minimum line width of 0.25 μm using an ArF laser. However, the use of these light sources requires the development of corresponding resists, but these resists are still in the process of research and require a considerable time for practical use. Although it is not impossible to replace the exposure light source with EB, the throughput is greatly reduced as compared with the exposure using light, which is not practical.

[0005] For these reasons, instead of shortening the wavelength of the conventional exposure light source, a method for promoting miniaturization without changing the exposure wavelength has been considered.

[0006] Techniques for promoting miniaturization without changing the exposure wavelength can be broadly classified into two methods: improvement of a resist surface and improvement of an optical surface. As the improvement of the resist surface, the improvement of the material itself or the improvement of the use of the resist, that is, CEL
Although a process and a multi-layer resist process are considered, any of the methods is effective for a pattern having a dimension larger than the exposure wavelength, but an effect cannot be expected for a pattern having a wavelength smaller than the exposure wavelength. This is because these techniques depend on the image contrast obtained via the optical system. Therefore, improvement of image contrast, that is, improvement of an optical surface is essentially required for miniaturization.

[0007] There are two types of optical surface improvement, one for the purpose of improving the image formation angle and the other for the purpose of reducing the interference between patterns. However, the conventional method greatly promotes miniaturization. According to Japanese Patent Publication No. Sho 62-50811, a technique is disclosed in which a phase member is provided in at least one of adjacent openings on an exposure mask to reduce interference of light passing through both openings. By using this method, the spatial frequency is reduced to １ ／, and the resolution performance is greatly improved, and it is possible to resolve a pattern having a size of about の of the resolution obtained conventionally.

However, in this method, it is difficult to exhibit the effect when three or more patterns are adjacent. That is, when the optical phase difference between the two patterns is 180 °, the other pattern has the same phase as one of the two patterns. As a result, the patterns having a phase difference of 180 ° are resolved, but the phase difference is 180 °. There is a problem that a pattern having a phase difference of 0 ° is not resolved. In order to solve this problem, it is necessary to fundamentally review the device design, and it is quite difficult to immediately put it into practical use.

There is a halftone type phase shift mask as a technique that uses a phase shift method for this technique and does not require a change in device design. In order to make the most of the effect of the phase shift method, it is important to optimize the phase difference between the light transmitted through the transparent portion and the translucent film and the amplitude transmittance ratio between the two. Each phase difference and the amplitude transmittance ratio between them are uniquely determined by the optical constants (complex refractive index n-ik: i is an imaginary unit) and the film thickness of these films. That is, in order to obtain a desired phase difference and amplitude transmittance, it is necessary that the optical constant and the film thickness satisfy a certain relationship. However, since the optical constant is a value specific to the substance, it is difficult to satisfy a desired condition with a single-layer film.

FIG. 26 shows the structure of an ideal conventional translucent phase film described in Japanese Patent Application No. 3-294540. The mask formed by this method is used for the light-transmitting substrate 110.
1 and a light transmissive film 1101b, and the light transmissive film 1101b is
Is formed at an amplitude transmittance ratio of 10% to 30%, and the phase of light passing therethrough is changed by 180 ° with respect to the light transmitting portion. A first layer 1102 and a first layer 1 for adjusting the amplitude transmittance to satisfy these objects.
A semi-transmissive film 1101b is formed by a two-layer structure including a second layer 1103 that adjusts the phase difference generated by the phase difference 102 to 180 °.

In Japanese Patent Application No. 3-294540, a phase shifter is made of a resin material which is transparent to exposure light to make the phase difference to the opening 180 °, and a dye is introduced into the resin to make the amplitude to the opening larger. A technique for adjusting the transmittance ratio is also described. In this case, the amplitude transmittance ratio is adjusted by a dye, and a transparent resin material is used as a phase adjustment layer so that the dye and the transparent resin material have a phase difference of 180 °.

As described above, in the conventional translucent phase shift mask, a plurality of substances are used irrespective of a single layer film or a multilayer film.
A desired amplitude transmittance and phase are intended to be obtained by using a different material as a material for adjusting the amplitude transmittance and a material for adjusting the phase as a laminated film or a mixed single layer film.

By the way, in the exposure step, a blind is provided in the projection exposure apparatus to prevent exposure light from leaking from the alignment or inspection mark other than the pattern area on the mask, and cuts off light outside the pattern area. . In addition, since the image of the blind causes an image of about 100 μm to fall on the wafer, it does not play a role of dividing the pattern area on the wafer. For this reason, the pattern area is conventionally divided by a light-shielding pattern existing around the pattern area on the mask.

[0014]

As described above, in one of the conventional translucent phase shift masks, the translucent portion has a two-layer structure, the amplitude transmittance is adjusted by the first layer 1102, and the second In the layer 1103, the angle is adjusted so as to be 180 ° together with the phase difference generated by the first layer 1102. However, in the case of a two-layer structure, pattern transfer is required, and the first layer and the second layer Because the layers are required to be machined to the same dimensions,
There is a problem that processing is extremely difficult.

Further, when a defect 1105 occurs in the lower layer 1102 of the first layer and the second layer, as shown in FIG. 27, there is a problem that it is very difficult to correct the defect.

Another method of the translucent phase shift mask is to introduce a dye into a transparent resin material for the purpose of adjusting the amplitude transmittance. In this method, two different substances are mixed to obtain a single-layer translucent film. Since a transparent film is used as a material for adjusting the phase, the production method is easy. However, a film that is transparent to the exposure wavelength has a refractive index at that wavelength of 1.2 to 2.0.
And the film thickness of the phase shifter increases. In an ordinary exposure apparatus, as shown in FIG. 12, exposure light 1003 is incident on a projection exposure substrate 1001 at an angle of about 3 ° with respect to a perpendicular to the substrate. Then, the mask pattern edge 100 on the substrate
In the vicinity of 5, a part of the illumination light 1004 is applied to the translucent pattern, causing image quality deterioration.

According to the present invention, a single layer film satisfies the conditions of the amplitude transmittance and the phase difference, and the image quality deterioration at the edge portion of the phase shift pattern is prevented by the current light shielding. An object of the present invention is to provide an exposure mask capable of maximizing the phase shift effect by suppressing the exposure mask to a value larger than the mask.

[0018]

Means for Solving the Problems Therefore, in the first invention,
The exposure mask includes, as a mask pattern, a translucent film pattern made of at least one of silicon, germanium, and gallium arsenide configured such that an optical path length for exposure light differs from a transparent portion by a predetermined amount.

Preferably, it is used for projection exposure using the g-line of a mercury lamp as an exposure light source.

According to a second aspect of the present invention, a film is formed by simultaneously adjusting the amplitude transmittance and the phase by simultaneously adjusting the amplitude transmittance and the phase by sputtering, using silicon, germanium or gallium arsenide as a target. A translucent phase shift pattern is obtained.

In the third aspect of the present invention, silicon, germanium, gallium arsenide, or an oxide of a metal such as Cr, Ti, or Al is used as a mask pattern so that the optical path length for exposure light differs from that of the transparent portion by a predetermined amount. And a translucent film pattern made of at least one of a material, a nitride and a halide.

According to a fourth aspect of the present invention, the transparent substrate contains at least one of silicon, germanium, gallium arsenide, or metal, oxide, nitride, or halide, and controls the element composition ratio of the compound. To form a translucent film pattern.

Preferably, in a sputtering environment, the amount of oxygen, nitrogen or halogen in the target or the reaction gas is adjusted to control the elemental composition ratio of the translucent film, thereby simultaneously controlling the amplitude transmittance and the phase difference while simultaneously controlling the oxide film and the nitride. A film or a halogenated film is obtained.

Further, the amplitude transmissivity of the translucent film may be adjusted by ion-implanting phosphorus, boron or arsenic partially or entirely on the target.

Further, as this translucent film,
Using the CVD method while adjusting the composition ratio of oxygen or nitrogen
Silicon oxide film or silicon nitride film may be formed
No. When forming a silicon oxide film, silicon
Orchids and CO_Two, O_TwoOr N _TwoO is used. Also,
Silanes as a source gas when forming a silicon nitride film
And NH_Three, N_TwoIs used.

The translucent film used in the first to fourth aspects of the present invention desirably has an amplitude transmittance ratio of 10% to 3 of the translucent film pattern to the opening on the translucent substrate.
0% and the phase difference with respect to the opening is 180 ° ± 1.
It is set to 0 °.

Preferably, the translucent film is formed as a single layer. In addition, a slightly oxidized region on the surface due to the use atmosphere is included as a single-layer film.

The refractive index of the translucent film used in the first to fourth inventions is desirably 2.03 or more.

When the translucent film is used at an exposure wavelength of 248 nm or more, the translucent film has an exposure wavelength of 240 nm.
, And has a refractive index equal to or higher than the value obtained by adding 1.

[0030]

According to Japanese Patent Application No. 3-294540, as a result of examining the light image intensity distribution projected on the wafer by changing the shifter transmittance by simulation, a predetermined transmittance is obtained instead of the light shielding film pattern. It is described that the use of a semi-transparent film pattern improves the contrast.

The present invention has been made in view of this point.
With the above configuration, the resolution of the fine pattern is facilitated. Further, since the patterning of the translucent film can be performed at one time similarly to the case of the light-shielding film, the pattern control is easy.

Regarding the first to fourth aspects of the present invention, the conditions and specific method for obtaining a single-layer semi-transparent film capable of obtaining a desired amplitude transmittance ratio and a phase difference with respect to the opening of the light-transmitting substrate will be described. State.

When an attempt is made to use a translucent film as a single layer, it is necessary to control the phase of light passing through the translucent film by 180 ° ± 10 ° with respect to the phase of light passing through the transparent portion.
In addition, it is necessary to set the transmittance of the translucent film to a desired value. The value of 10 ° is first determined by simulation to determine the depth of focus at a phase difference of 180 °, and the phase difference is set to 18 °.
The angle is shifted from 0 °, and the deterioration of the depth of focus in that case is determined as a range within 10% as compared with the depth of focus at a phase difference of 180 °.

In order to obtain the maximum resolution with a translucent film phase shift mask, the optical constant of the translucent film must satisfy the following conditions.

Assuming that the complex electric field vector of the incident light is E0, the complex electric field vector of the light transmitted through the transparent region is E1, and the complex electric field vector of the light transmitted through the translucent film is E2, the relationship between them is as follows.

[0036]

(Equation 1)

Is as follows.

In order to obtain the maximum effect with the phase shift mask, the relational expression between the amplitude transmittance ratio of transmitted light and the phase difference is expressed by Expressions 3 and 4.

[0039]

(Equation 2)

## EQU4 ## In Equations 1 and 2, the amplitude transmittances t1 and t2 of the light in the translucent film area and the transmission area are the reflectance, the transmittance, and the absorbance of the film at the interface between the material constituting these areas and another medium. Considered film thickness T of the substance
Can be easily obtained by considering the multiple reflection in the above. The reflectance and transmittance of the substance are the refractive index n and the extinction coefficient k
More required. The absorbance of the film can be obtained from the extinction coefficient k.

Since the translucent film in question is a phase shifter layer, considering the phase difference of 180 ° with respect to the opening, the film thickness T1 is smaller than the refractive index n of the substance.

[0042]

(Equation 3)

Is as follows. The transmittance t obtained as an actual measurement value from the above variables is

[0044]

(Equation 4)

Is obtained. Here, n0 and k0 indicate the refractive index, extinction coefficient, and film thickness of the medium, and are specific values. In addition, since T1 satisfies the relationship of (Equation 5), (Equation 6) is defined as the relationship of n1 and k1, and the amplitude transmittance t when an arbitrary phase difference with respect to the aperture is given is determined first. Can be.

Based on the above concept, for example, the wavelength 436
Assuming a g-line exposure of nm, the phase is set to 180 ± 10 °, the amplitude transmittance is set to 15 ± 5%, the refractive index n is changed, and the corresponding k is determined. (FIG. 8). In FIG. 8, the vertical axis indicates the extinction coefficient k, the horizontal axis indicates the refractive index n, and the broken line (a) indicates a curve indicating the relationship between k and n when the amplitude transmittance is 10% and the phase is 170 °. b) is k and n when the amplitude transmittance is 20% and the phase is 190 °.
The solid line (c) shows the amplitude transmittance of 15%,
It is a curve which shows the relationship between k and n at the time of a phase of 180 degrees.
The region between the dashed lines (a) and (b) is an allowable range at this time. If the region is between the dashed lines determined by the refractive index n and the extinction coefficient k of a certain material, the material is a single-layer film. It has the function of a translucent film.

In the case of the g-line, a film satisfying this condition is used as shown in FIG.
There is amorphous Si indicated by a point in it. Also,
It can be seen that germanium (FIG. 15) and gallium arsenide (FIG. 16) are also within the allowable range. In this case, a single-layer translucent film can be obtained with a single substance.

On the other hand, when i-line exposure with a wavelength of 365 nm is given, amorphous Si (point of N ₂ gas 0%) takes a value outside the allowable range (FIG. 9). Therefore, it is understood that it is impossible to form a single-layer translucent film using amorphous Si by i-line exposure. Further, Si ₃ N ₄ (N
_If the same examination is performed for ₂ gas 80% point), the result is also out of the allowable range (FIG. 9). However, it can be seen that when two points of amorphous Si and Si ₃ N ₄ are connected by an arbitrary curve, an area sandwiched between the broken lines is always obtained. That is, if there is a substance having an intermediate property between amorphous Si and Si ₃ N ₄ , the substance falls within the allowable range. For the formation of this film, reactive sputtering using Si and N ₂ is effective. At this time, a film having any physical properties can be obtained by changing the reaction ratio of N ₂ . The physical property values at this time are indicated by black circles. Also,
When the curve passing through the black circle is drawn, it passes through the region between the broken lines, and the optimum conditions obtained here are n = 3.30 and k = 1.19 when the flow rate of the nitrogen gas during sputtering is 15%, By setting the film thickness to 83.5 nm, the amplitude transmittance ratio is set to 0.4.
142, the phase difference becomes 180 °. By forming a SiNβ film (0 <β <1.33) in which the element composition ratio is changed in this way, a desired single-layer semitransparent film can be formed.

Also, when exposure with an excimer laser having a wavelength of 248 nm is considered, the physical property values of amorphous Si and SiNβ ′ (0 <β ′ <1.33) are out of the allowable range, as in the case of i-line exposure. However, it was found that substances having these intermediate physical properties were within the allowable range. (Figure 1
0).

The elemental composition ratio β = (N / Si) is preferably about 0.3 to 0.8 in the case of an i-line exposure mask. In the case of KrF laser exposure, approximately β ′ =
It is good to be 0.7-1.2.

In the case of the g-line, the film quality may not be in a desired range depending on the film forming conditions. In this case, by controlling the pressure, temperature, etc. during film formation,
By changing the refractive index and the extinction coefficient, a desired film can be obtained.

The boundary condition can be set with a phase difference fixed at 180 ° so that the amplitude transmittance has a margin, or the amplitude transmittance can be fixed and the phase can be set with a margin. is there. Also, the allowable values may be changed from the values described in this description in consideration of the effects and effects on the resist process and the like.

As a result of our intensive research as a material satisfying the above conditions, it has been found that silicon, germanium, gallium arsenide or metal oxides, nitrides or halides are formed of one or more of them. It was found that the above-mentioned two conditions were satisfied for the substance.

By implanting ions such as As, P, and B into the translucent film, the quality of the formed film can be slightly adjusted, for example, the optical constant can be adjusted.

By heating Si to 500 ° C. or higher, the amorphous state can be continuously or intermittently changed from a polycrystalline state to a polycrystalline state or from a polycrystalline state to a single crystal state. can get.

Therefore, in the fourth invention, a desired value can be obtained by controlling the composition ratio. Here, since the optical constant is a value inherent to the substance, it is impossible to set an arbitrary value. Therefore, the optical constant can be optimized by, for example, changing the composition ratio of the compound.

By satisfying the above conditions, it is possible to obtain a desired retardation and transmittance with a single-layer semi-transparent film.

Incidentally, in a halftone type phase shift mask, a translucent pattern is provided instead of a light shielding film made of Cr or the like in a normal mask. By using this translucent film as a phase shifter, the light shielding effect can be enhanced by utilizing the light interference at the edge portion.

However, in the halftone type phase shift mask, the dimension conversion between the dimension of the semi-transparent pattern and the pattern actually exposed on the wafer using this mask is relatively larger than that of the conventional mask. It is known that a difference occurs, and this value cannot be ignored particularly when a fine pattern is formed using a phase shift mask. The amount of the conversion difference varies depending on the size, shape, etc. of the pattern, but it is possible to know in advance how to correct the pattern size of the mask by simulation or experiment.

Therefore, a translucent film pattern is formed in consideration of the dimensional conversion difference. Further, in the halftone type phase shift mask, it has been confirmed by simulation that when the side wall portion of the translucent film is rounded, the phase shift effect is reduced due to interference of light at an edge portion.

Therefore, in the translucent film pattern forming process, the roundness of the side wall caused by isotropic etching is made vertical by performing side etching, and the amount of side etching at this time is adjusted to reduce the dimensional conversion difference. A semi-transparent film having a dimension considered is formed. In this case, the dimensions of the translucent film pattern when the isotropic etching is performed need to be formed relatively large.

In the translucent film pattern forming process, since the anisotropic etching is performed, the translucent film pattern side wall is formed relatively vertically. In this case, it is necessary to form the dimensions of the translucent film pattern when performing the anisotropic etching in a size in consideration of the dimensional conversion difference.

Further, a photosensitive resin pattern having the same size as the translucent film pattern in consideration of the dimensional conversion difference is formed on the translucent substrate, and the region of the photosensitive resin pattern excluding the side wall is translucent. A film is formed by sputtering or the like.
At this time, if the photosensitive resin pattern is formed in a reverse taper shape, it is possible to prevent the formation of a translucent film on the side wall of the photosensitive resin pattern due to the protruding pattern corner.

FIG. 11 shows a standardized size of 0.74 μm.
4 shows the depth of focus with respect to the dimensional conversion difference of the pattern. Here, the depth of focus indicates a defocus amount within ± 10% of a desired dimension. From FIG. 11, the difference in dimensional conversion is to make the translucent pattern of 0.074 μm thin on the wafer, that is, assuming that the exposure magnification of the exposure apparatus is a, the maximum depth of focus is obtained when the translucent pattern is made 0.074 a thin on the mask. Is obtained. In addition, standard size 0.45μ
For the m pattern, the depth of focus with respect to the dimensional conversion difference was determined. The dimensional conversion difference narrowed the translucent pattern by 0.040 μm on the wafer. That is, when the exposure magnification of the exposure apparatus was a, the translucent pattern was reduced to 0 on the mask. It has been found that the maximum depth of focus is obtained when the focal length is reduced by 0.040a. It can be seen that in order to obtain the maximum depth of focus, the translucent pattern should be narrowed by 0.1 b on the wafer, ie, 0.1 b / a on the mask, with respect to the desired dimension b.

As described above, when the dimensional conversion difference is set to the exposure magnification a of the exposure apparatus with respect to the desired dimension b, the translucent pattern can be narrowed by 0 to 0.1 b / a relative to the circuit design dimension. preferable.

Further, by using a substance having a refractive index of 2.03 or more for the translucent film in the first to fourth inventions, a pattern having a sufficient depth of focus can be formed.

Preferably, the exposure wavelength is set to 240 for a translucent film used when the exposure wavelength is 248 nm or more.
By using a translucent film having a refractive index equal to or greater than the value obtained by adding 1 after dividing by nm, image quality degradation can be suppressed to the same level or more as that of a currently used light-shielding mask.

FIG. 12 shows the reflection of the irradiation light at the edge of the mask pattern to explain the deterioration of the illumination light. A translucent mask pattern 1002 is arranged on a projection exposure substrate 1001. The illumination light 1003 that forms an image in the vicinity of the edge forms an image at an angle θ with respect to a perpendicular to the substrate. In this case, the illumination light forms an image on the mask pattern surface without being affected by reflection or the like. However, in the light 1004 that forms an image on the edge side than the illumination light 1003, it is expected that a part of the illumination light will be applied to the translucent pattern and image quality will deteriorate.

The area x where image quality degradation occurs can be obtained by the following procedure. Hereinafter, x will be determined in order. Using the numerical aperture NA of the exposure apparatus, the coherent factor σ, and the exposure magnification a, the sin of the imaging angle θ of the illumination light on the projection exposure substrate is obtained.

[0070]

(Equation 5)

Can be expressed as follows. The region x uses the thickness T of the translucent film and the image formation angle θ.

[0072]

(Equation 6)

Further, this translucent film is a single layer and has a retardation of 1
Since 80 ° is satisfied, (Equation 5) is substituted into (Equation 8)

[0074]

(Equation 7)

Is obtained. Here, n is the refractive index of the translucent film. Next, this x is normalized by dividing it by λ / NA in order to obtain a value independent of the wavelength and NA, and further converted into a dimension X on the wafer.

[0076]

(Equation 8)

Is obtained.

When a translucent film shifter is used, Table 1 shows desired patterns, exposure wavelengths for achieving the desired patterns, NA of the exposure apparatus, and dimensions standardized by λ / NA. Thus, it can be said that the desired resolution dimension of the translucent mask is about 0.45 μm in standardized dimension.

The ratio ε occupied by the area X causing the image quality degradation with respect to the standardized size is obtained. Here, since the region X exists at both edges of the pattern,

[0080]

[Table 1]

[0081]

(Equation 9)

Is obtained.

FIG. 13 shows the allowable ε obtained by an exposure experiment. The result is an amplitude transmittance of 15%
Shows the characteristics of a 0.325 μm pattern transferred by an exposure apparatus with an NA of 0.5 using an i-line as an exposure light source using a mask shown in FIG. Are normalized by the maximum depth of focus. Assuming that the depth of focus can be reduced to 10% for this pattern,
It is necessary to make ε 0.013 or less.
Applying to 4, the value required for the refractive index n of the translucent film is

[0084]

(Equation 10)

## EQU10 ##

As described above, when the latitude of the depth of focus is considered, the refractive index of the translucent film is 2.03 regardless of the wavelength.
It is desirable that this is the case.

Incidentally, this image quality deterioration always occurs as long as the mask pattern has a film thickness, and naturally occurs even with the current light shielding mask. When forming a pattern with a translucent film, it is necessary to at least reduce the image quality degradation to less than the conventional light-shielding film. In a conventional mask, for example, the thickness of a mask substrate provided with a double-sided antireflection film is about 120 nm. When trying to suppress image quality degradation below this mask,
From this film thickness and (Equation 5)

[0088]

[Equation 11]

The following relationship is obtained. At this time, as can be seen from (Equation 13), the allowable value of the refractive index of the translucent film is the exposure wavelength λ.
(Nm), and the tolerance of each exposure wavelength is as shown in Table 2.

[0090]

[Table 2]

As shown in Table 2, when each exposure wavelength is used as a light source, the refractive index of the translucent film is set to the g-line (436n
By setting it to 2.81 or more in the case of m) and to 2.52 or more in the case of the i-line (365 nm), it is possible to suppress image quality deterioration at least to the same extent as the current light-shielding mask. Table 2
From the results of (Expression 12) and (Expression 12), when the exposure wavelength is 248 nm or less, it is preferable to determine the refractive index in consideration of the depth of focus margin. In this case, the refractive index of the translucent film is set to 2.0.
It is preferable that the number be 3 or more.

The transmittance t 'in a substance is determined by the extinction coefficient k, the wavelength λ, and the film thickness T.

[0093]

(Equation 12)

Can be expressed as follows. Take the logarithm of both sides,
Further, by substituting (Equation 5) into (Equation 14), and obtaining about k,

[0095]

(Equation 13)

Can be expressed as follows. The range of the intensity transmittance t '/ to of the translucent film is 0.01 <t' / to <
0.09, but to satisfy the intensity transmittance of 0.09 or less now

[0097]

[Equation 14]

It is necessary that From Equations 16 and 12, the desired k is

[0099]

(Equation 15)

Is obtained. Although the above considerations do not take into account multiple reflections, when multiple reflections are taken into account, k is (Equation 1).
7) Take a larger value.

Table 3 shows the physical properties of the single-layer semi-transparent film and the substance satisfying the condition of the refractive index. The suitability shown in Table 3 is determined based on the refractive index and the amplitude transmittance, and satisfies the range of the amplitude transmittance ratio of 10% to 30% with respect to the opening.
Satisfies the condition of the refractive index calculated in consideration of the depth of focus margin, and ○ satisfies the condition of the refractive index, and ◎ satisfies the condition of the image quality which can be suppressed more than the current light shielding mask. However, those that do not satisfy the condition of the amplitude transmittance are indicated by Δ.

In particular, for silicon, the g-line region, S
It can be said that iNβ is a very effective translucent film in the i-line and KrF regions. Although not shown in the table, SiOα is a translucent film that is effective in the i-line, KrF, and ArF regions.

Although the present invention relates to a translucent film that transmits little light, the translucent film has another use. In the conventional mask, the intensity of light reaching the wafer varies depending on the density of the mask pattern. In this case, there was a problem that a pattern dimension difference occurred at the time of development.However, in order to prevent a difference in light intensity, a technique of absorbing light in a film to suppress light intensity transmitted through a relatively large aperture pattern has been made. ing. Even in a phase shift mask, in order to suppress the difference in the mask pattern density, a method is used in which the amplitude transmittance is set to about 90% with a relatively large aperture pattern and the exposure amount is balanced. This method mainly uses a material with a different refractive index from the translucent substrate as the phase shifter, and utilizes the reflection at the interface between the phase shifter and the translucent substrate,
This has been done by substantially reducing the transmitted light of the phase shifter. For example, TiO _{2 which} has no absorption in the film itself in the g-line region
When a film is used, almost 100% of the absorption of the film is transmitted because the extinction coefficient is 0.01 or less. However, since the refractive index of the film is 2.8, light incident from the light-transmitting substrate is TiO
_Since about 10% of the light is reflected at the interface with the _two films, the transmittance of this portion is substantially reduced, and 90% of the light can be transmitted. Although the Si ₃ N ₄ film has an extinction coefficient of 0.01 or less in the i-line region, it transmits almost 100%.
Since the refractive index of the film is 2.0, about 3% of the light incident from the light-transmitting substrate is reflected at the interface with the Si ₃ N ₄ film. Light can be transmitted.

As described above, the phase shifter having a high transmittance is
Use a substance with an extinction coefficient of 0.01 or less to obtain a desired reflectance.
By using a film with a refractive index
Was possible. Controlling the exposure difference in this way
This method is effective for translucent films that
TiO_TwoSi in film or i-line region_ThreeN _Four
Even when a film is used, oxygen or nitrogen during sputtering may be used.
Desired considering reflectivity by controlling elemental composition ratio
Can be obtained.

[0105]

[Table 3]

[0106]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described in detail with reference to the drawings.

Example 1 This example relates to a method for manufacturing an exposure mask according to the first invention and a method for manufacturing an exposure mask according to the second invention. FIG. 1 is a view showing a manufacturing process of the exposure mask of this embodiment.

This exposure mask is characterized by using a silicon pattern formed by a sputtering method as a semi-transparent pattern, and is used as a g-line projection exposure mask.

First, an amorphous Si film 102 is formed on a silicon oxide substrate 101 by a sputtering method (FIG. 1A). The refractive index of the silicon film 102 with respect to the g-line of the mercury lamp is n = 4.93, and the phase difference is 18
The film thickness at which the angle was 0 ° was 59 nm. At this time, the amplitude transmittance was 17.4% with respect to the amplitude transmittance of the silicon oxide substrate 101 as a transparent portion.

Next, an electron beam resist 103 is applied to a thickness of 0.
After deposition at 5 μm, the conductive film 104 is further
(FIG. 1B).

Then, drawing is performed on the conductive film 104 with an electron beam at 3 μC / cm ² , and further development is performed to form a resist pattern 103 (FIG. 1C). Here, the conductive film 104 is formed because the silicon oxide substrate and the amorphous Si film are insulative and prevent charge-up during electron beam exposure.

Using the resist pattern 103 as a mask, the amorphous Si film 102 exposed from the resist pattern is removed by chemical ion etching (CDE) using a mixed gas of CF ₄ and O ₂ (FIG. 1D). .

Finally, the resist pattern 103 is removed to obtain the amorphous Si pattern 102 (FIG. 1E).

In this example, an amorphous Si film was formed as a phase shifter by sputtering.
A CVD method may be used. Further, the thickness of the amorphous Si film may be set to an appropriate thickness without departing from the scope of the present invention.

Furthermore, the processing of the silicon film may be performed by anisotropic etching.

[0116] In the present invention SiO ₂ as a light-transmitting substrate
It was used MgF ₂ instead of SiO _2, CaF _2, A
l ₂ O ₃ or the like may be used.

In the present invention, the transmittance of the translucent film may be set to an appropriate transmittance without departing from the spirit of the present invention.
Note that the optical characteristics of the translucent film can be finely adjusted by injecting ions such as arsenic, phosphorus, and boron into the translucent film or by applying heat.

When a substrate in which a conductive film is formed on a light-transmitting substrate is used instead of the SiO ₂ substrate, the coatable conductive film becomes unnecessary. When the mask pattern is drawn by light exposure, the conductive film can be eliminated.

Through a mask for exposure formed in this way, a substrate called PFR7750 (manufactured by Nippon Synthetic Rubber Co., Ltd.) coated with 1.5 μm of resist was exposed to g-line at 1/5 reduction exposure (NA = 0.54, σ = 0.5) to form a line & space pattern. The exposure required at this time was 300 mJ / cm ² . 0.45 with conventional exposure
What has been resolved with a focus margin of 0 μm in a pattern of μm is replaced by a mask of the present invention.
Resolution was possible at 7 μm.

Regarding the contact hole pattern, it was confirmed that the 0.50 μm pattern which was not resolved by the conventional exposure was resolved with the focus margin of 1.5 μm by the mask of the present invention.

Further, by transferring using this mask and processing the substrate using the formed resist pattern as a mask, it becomes possible to obtain a better processed shape.

Even if the surface of the translucent film is naturally oxidized, the effect of the present invention is not lost.

(Embodiment 2) This embodiment relates to a method for manufacturing an exposure mask according to the first invention and a mask for exposure according to the second invention.

This exposure mask is characterized by using a Ge pattern formed by a sputtering method as a translucent pattern, and is used as a g-line projection exposure mask.

First, a Ge film is formed on a silicon oxide substrate by a sputtering method. The refractive index of this Ge film with respect to the g-line of the mercury lamp is n = 4.10, and the phase difference is 18
The film thickness at which the angle was 0 ° was 70.3 nm. The amplitude transmittance at this time was 10.8% with respect to the amplitude transmittance of the silicon oxide substrate as the transparent portion.

Then, in the same manner as in Example 1, a resist for electron beam was deposited to a thickness of 0.5 μm, and a conductive film was further
It is formed to about μm. Then, drawing is performed on the conductive film at 3 μC / cm 2 with an electron beam, followed by development to form a resist pattern. Using this pattern as a mask, chemical ion etching (CDE) using Cl2 gas
As a result, the Ge film exposed from the resist pattern is removed by etching. Finally, the Ge pattern can be obtained by removing the resist pattern.

In this way, a single-layer phase shifter made of a desired translucent film can be obtained.

In this example, a Ge film was formed as a phase shifter by sputtering, but an evaporation method may be used. The Ge film may have an appropriate thickness without departing from the scope of the present invention.

Further, the Ge film may be processed by anisotropic etching, and a fluorine-based gas such as CF ₄ , C ₂ F
It is also possible to use ₆ or the like.

In the present invention, SiO _{2 is used} as the light-transmitting substrate.
It was used MgF ₂ instead of SiO _2, CaF _2, A
l ₂ O ₃ or the like may be used.

In the present invention, the transmittance of the translucent film may be set to an appropriate transmittance without departing from the gist of the present invention.
The optical characteristics of the translucent film can be finely adjusted by injecting ions such as arsenic, phosphorus, and boron into the translucent film or by applying heat.

When a substrate in which a conductive film is formed on a light-transmitting substrate is used instead of the SiO ₂ substrate, the coating conductive film becomes unnecessary. When the mask pattern is drawn by light exposure, the conductive film can be eliminated.

Through the exposure mask thus formed, a substrate called PFR7750 (manufactured by Nippon Synthetic Rubber Co., Ltd.) coated with 1.5 μm of resist was exposed to g-line at 1/5 reduction exposure (NA = 0.54, σ = 0.5) to form a line & space pattern. The exposure required at this time was 300 mJ / cm ² . 0.45 with conventional exposure
What has been resolved with a focus margin of 0 μm in a pattern of μm is replaced by a mask of the present invention.
Resolution was possible at 7 μm.

Regarding the contact hole pattern, it was confirmed that the 0.50 μm pattern, which was not resolved by the conventional exposure, was resolved by the mask of the present invention with a focus margin of 1.5 μm.

The effect of the present invention is not lost even if the surface of the translucent film is slightly oxidized naturally.

(Embodiment 3) This embodiment relates to a method of manufacturing an exposure mask of the third invention and a method of manufacturing an exposure mask of the fourth invention.
More particularly, the present invention relates to an exposure mask using i-line as an exposure light source and a method for manufacturing the same.

The present exposure mask relates to a projection exposure mask characterized by using a silicon nitride pattern formed as a translucent pattern by controlling the composition ratio of nitrogen in a reaction gas by a sputtering method.

First, a silicon nitride film 202 is formed on a silicon oxide substrate 201 by a sputtering method using silicon as a target and adding a predetermined amount of a mixed gas of nitrogen and argon (nitrogen content: 15%) (FIG. 2A). ). The refractive index of this silicon nitride film with respect to KrF is n = 3.4.
0, and the film thickness at which the phase difference was 180 ° was 80 nm. The amplitude transmittance ratio to the transparent portion was 15.1%.

Then, in the same manner as in Examples 1 and 2, an electron beam resist 203 is deposited to a thickness of 0.5 μm, and then a conductive film 204 is formed to a thickness of about 0.2 μm (FIG. 2).
(B)). Then, from the conductive film, 3 μm
The resist pattern 203 is formed by drawing at C / cm ² and further developing (FIG. 2C). Using this resist pattern as a mask, the silicon nitride film 202 exposed from the resist pattern is etched away by chemical ion etching (CDE) using a mixed gas of CF ₄ and O ₂ (FIG. 2D). Finally, the resist pattern 203 is immersed in a mixed solution of sulfuric acid and hydrogen peroxide to form a resist pattern 203.
Is removed to obtain a silicon nitride pattern 202 (FIG. 2E).

In this example, a silicon nitride film was formed as a phase shifter by sputtering using silicon as a target. However, sputtering using a mosaic target of silicon and silicon nitride whose area ratio was adjusted in advance, or ammonia and silane C using system gas
The VD method may be used. Further, the thickness of the silicon nitride film may be set to an appropriate thickness without departing from the spirit of the present invention.

Further, the silicon film may be processed by anisotropic etching.

In the present invention, SiO _{2 is used} as the light-transmitting substrate.
It was used MgF ₂ instead of SiO _2, CaF _2, A
l ₂ O ₃ or the like may be used.

In the present invention, the transmittance of the translucent film may be set to an appropriate value without departing from the spirit of the present invention.
The optical characteristics of the translucent film can be finely adjusted by injecting ions such as arsenic, phosphorus, and boron into the translucent film or by applying heat.

When a substrate in which a conductive film is formed on a light-transmitting substrate is used instead of the SiO ₂ substrate, the coating conductive film becomes unnecessary. When the mask pattern is drawn by light exposure, the conductive film can be eliminated.

Further, in this embodiment, electron beam is used for drawing at the time of making a mask, but light may be used instead of electron beam. When light is used, a photosensitive resin material and a conductive film provided over a light-transmitting substrate are not required.

Through the exposure mask thus formed, a substrate coated with an i-line-like resist, referred to as PERIX500 (manufactured by Nippon Synthetic Rubber Co., Ltd.), 1.5 μm, was subjected to 1/5 reduction exposure with i-line. (NA = 0.5, σ = 0.6) to form a line & space pattern. The exposure required at this time was 300 mJ / cm2. With conventional exposure,
What had been resolved with a focus margin of 0 μm using a 0.35 μm pattern could be resolved with a focus margin of 0.8 μm using the mask of the present invention.

Regarding the contact hole pattern, it was confirmed that the 0.40 μm pattern which was not resolved by the conventional exposure was resolved with the focus margin of 1.3 μm by the mask of the present invention.

The effect of the present invention is not lost even if the surface of the translucent film is slightly naturally oxidized.

(Embodiment 4) This embodiment relates to a method for manufacturing an exposure mask according to the third invention and a method for manufacturing an exposure mask according to the fourth invention.
In particular, the present invention relates to an exposure mask using a KrF laser as an exposure light source and a method for manufacturing the same.

This exposure mask relates to a projection exposure mask for KrF (248 nm), wherein a silicon nitride pattern formed by a sputtering method is used as a translucent pattern.

First, a silicon nitride film is formed on a silicon oxide substrate by sputtering using silicon as a target and adding a predetermined amount of a mixed gas of argon and nitrogen.
The refractive index of this silicon nitride film with respect to KrF is n = 2.
The film thickness at which the phase difference was 180 ° was 76 nm. The amplitude transmittance at this time was 15% with respect to the amplitude transmittance of the silicon oxide substrate as the transparent portion.

Then, in the same manner as in Examples 1 and 2, an electron beam resist is deposited to a thickness of 0.5 μm, and then a conductive film is formed to a thickness of about 0.2 μm. Then, drawing is performed on the conductive film with an electron beam at 3 μC / cm ² , and development is performed to form a resist pattern. Using this resist pattern as a mask, the silicon nitride film exposed from the resist pattern is removed by chemical ion etching (CDE) using a mixed gas of CF ₄ and O ₂ . Finally, the resist pattern is removed to obtain a silicon nitride pattern.

In this example, a silicon nitride film is formed as a phase shifter by sputtering, but a CVD method using ammonia and a silane-based gas may be used. Further, the thickness of the silicon nitride film may be set to an appropriate thickness without departing from the spirit of the present invention.

Further, the silicon film may be processed by anisotropic etching.

In the present invention, SiO _{2 is used} as the light-transmitting substrate.
It was used MgF ₂ instead of SiO _2, CaF _2, A
l ₂ O ₃ or the like may be used.

In the present invention, the transmittance of the translucent film may be set to an appropriate value without departing from the spirit of the present invention.
The optical characteristics of the translucent film can be finely adjusted by injecting ions such as arsenic, phosphorus, and boron into the translucent film or by applying heat.

In the case where a substrate in which a conductive film is formed on a light-transmitting substrate is used instead of the SiO ₂ substrate, the coatable conductive film becomes unnecessary. When the mask pattern is drawn by light exposure, the conductive film can be eliminated.

Further, in this embodiment, electron beams are used for drawing at the time of forming a mask, but light may be used instead of electron beams. When light is used, a photosensitive resin material and a conductive film provided over a light-transmitting substrate are not required.

Through a mask for exposure formed in this way, a substrate coated with a 1.0 μm KrF resist called SNR (manufactured by Shipley Co.) was subjected to 1/5 reduction exposure (NA = 0.4, σ = 0.5) to form a line & space pattern. The exposure required at this time was 40 mJ / cm ² . 0.30μm with conventional exposure
What was resolved with a focus margin of 0 μm in the pattern was changed to a focus margin of 0.7 μm by the mask of the present invention.
m could be resolved.

Regarding the contact hole pattern, it was confirmed that the 0.30 μm pattern, which was not resolved by the conventional exposure, was resolved by the mask of the present invention with a focus margin of 1.2 μm.

The effect of the present invention is not lost even if the surface of the translucent film is slightly oxidized naturally.

(Embodiment 5) This embodiment is directed to a method for manufacturing an exposure mask according to the third invention and a method for manufacturing an exposure mask according to the fourth invention.
More particularly, the present invention relates to an exposure mask when i-line is used as an exposure light source and a method of manufacturing the same.

This exposure mask relates to an i-line projection exposure mask characterized by using a chromium oxide pattern formed as a translucent pattern by controlling the composition ratio of oxygen by a sputtering method.

First, a chromium oxide film is formed on a silicon oxide substrate by sputtering using chromium as a target and adding a predetermined amount of a mixed gas of oxygen and argon. As shown in FIG. 17, the refractive index of this chromium oxide film with respect to the i-line was n = 2.40, and the thickness at which the phase difference was 180 ° was 130 nm. At this time, the amplitude transmittance was 26.1% with respect to the amplitude transmittance of the silicon oxide substrate as the transparent portion.

Then, in the same manner as in Example 3, an electron beam resist was deposited to a thickness of 0.5 μm, and then a conductive film was further
It is formed to about μm. Then, drawing is performed on the conductive film with an electron beam at 3 μC / cm ² , and development is performed to form a resist pattern. Using this resist pattern as a mask, chemical ion etching (CD
E), the chromium oxide film exposed from the resist pattern is removed by etching. Finally, the resist pattern is immersed in a mixed solution of sulfuric acid and hydrogen peroxide to remove the resist pattern, thereby obtaining a chromium oxide pattern.

The chromium oxide film may have an appropriate thickness without departing from the spirit of the present invention.
Further, the processing of chromium oxide can be performed by reactive ion etching (RIE).

In the present invention, SiO _{2 is used} as the light-transmitting substrate.
It was used MgF ₂ instead of SiO _2, CaF _2, A
l ₂ O ₃ or the like may be used.

In the present invention, the transmittance of the translucent film may be set to an appropriate value without departing from the spirit of the present invention.
The optical characteristics of the translucent film can be finely adjusted by injecting ions such as arsenic, phosphorus, and boron into the translucent film or by applying heat.

When a substrate in which a conductive film is formed on a light-transmitting substrate is used instead of the SiO ₂ substrate, the coating conductive film becomes unnecessary. When the mask pattern is drawn by light exposure, the conductive film can be eliminated.

Further, in this embodiment, electron beams are used for drawing at the time of mask formation, but light may be used instead of electron beams. When light is used, a photosensitive resin material and a conductive film provided over a light-transmitting substrate are not required.

[0171] A 1/5 reduction exposure with i-line was performed on a substrate coated with a 1.2 μm i-line resist called PFRIX500 (manufactured by Nippon Synthetic Rubber Co.) through the exposure mask thus formed. (NA = 0.5, σ = 0.6), the 0.40 μm pattern not resolved by the conventional exposure is resolved with the focus margin of 1.5 μm by the mask of the present invention. It was confirmed that. This exposure mask was unsuitable for forming a line & space pattern, such as a decrease in the residual film ratio of the resist, because of high transmittance. The line and space pattern is preferably formed with an amplitude transmittance of 10% to 20%. In the case of a chromium oxide mask, the amplitude transmittance can be formed at about 20%. This amplitude transmittance is 2
A line & space pattern was formed using a 0% exposure mask. The exposure required at this time was 300 mJ / cm ² . What had been resolved with a 0.35 μm pattern focus margin of 0 μm by conventional exposure could be resolved with a focus margin of 0.6 μm using the mask of the present invention.

When the chromium oxide film is used as the translucent film for i-line, the film quality is slightly thicker than that of the light-shielding film used in the conventional mask, and the image quality is deteriorated. As described above, it is not impossible to apply a chromium oxide film to a translucent film, but it is difficult to maximize its performance.

The chromium oxide film is also applicable to a g-line exposure mask as shown in FIG. However, even in this case, the image quality has deteriorated because the film thickness is slightly thicker than the light-shielding film used in the conventional mask, and it is not impossible to apply the chromium oxide film to the translucent film. It is difficult to demonstrate.

On the other hand, when used for a KrF laser, C
Neither r nor CrO ₂ is applicable because the extinction coefficient is out of the allowable range. However, in FIG. 19, the lower limit of the amplitude transmittance is set to 10%. However, if the desired depth of focus is not so large, the amplitude transmittance can be set to 10% or less. Can also be applied.

(Embodiment 6) This embodiment relates to a method for manufacturing an exposure mask according to the third invention and a method for manufacturing an exposure mask according to the fourth invention,
More particularly, the present invention relates to an exposure mask when i-line is used as an exposure light source and a method of manufacturing the same.

This exposure mask relates to an i-line projection exposure mask characterized by using a titanium oxide pattern formed as a translucent pattern by controlling the composition ratio of oxygen by sputtering.

First, a titanium oxide film is formed on a silicon oxide substrate by sputtering using a target of titanium and adding a predetermined amount of a mixed gas of oxygen and argon. The refractive index of this titanium oxide film with respect to the i-line is n = 2.70 as shown in FIG.
07 nm. The amplitude transmittance at this time was 15% with respect to the amplitude transmittance of the silicon oxide substrate as the transparent portion.

Then, in the same manner as in Example 3, a resist for electron beam was deposited to a thickness of 0.5 μm, and then a conductive film was further
It is formed to about μm. Then, drawing is performed on the conductive film with an electron beam at 3 μC / cm ² , and development is performed to form a resist pattern. Using this resist pattern as a mask, the titanium oxide film exposed from the resist pattern is etched away by chemical ion etching (CDE) using CF ₄ gas. Finally, the resist pattern is removed by immersion in a mixed solution of sulfuric acid and hydrogen peroxide solution to obtain a titanium oxide pattern.

In this example, a titanium oxide film was formed as a phase shifter by sputtering using titanium as a target. However, sputtering was performed using a mixed target of titanium and titanium oxide whose area ratio was adjusted in advance. Is also good. Further, the thickness of the titanium oxide film may be set to an appropriate thickness without departing from the spirit of the present invention.

The processing of the titanium oxide film may be performed by anisotropic etching.

In the present invention, SiO _{2 is used} as the light-transmitting substrate.
It was used MgF ₂ instead of SiO _2, CaF _2, A
l ₂ O ₃ or the like may be used.

In the present invention, the transmittance of the translucent film may be set to an appropriate value without departing from the scope of the present invention.
The optical characteristics of the translucent film can be finely adjusted by injecting ions such as arsenic, phosphorus, and boron into the translucent film or by applying heat.

When a substrate in which a conductive film is formed on a light-transmitting substrate is used instead of the SiO ₂ substrate, the coating conductive film is not required. When the mask pattern is drawn by light exposure, the conductive film can be eliminated.

In the present embodiment, electron beams are used for drawing at the time of mask production, but light may be used instead of electron beams. When light is used, a photosensitive resin material and a conductive film provided over a light-transmitting substrate are not required.

Through a mask for exposure formed in this way, a substrate called PFRIX500 (manufactured by Nippon Synthetic Rubber Co., Ltd.) coated with an i-line resist of 1.5 μm was exposed by i-line to 1/5 reduction exposure. (NA = 0.5, σ = 0.6) to form a line & space pattern. The exposure required at this time was 300 mJ / cm ² . With conventional exposure,
What had been resolved with a 0.35 μm pattern focus margin of 0 μm could be resolved with a focus margin of 0.8 μm using the mask of the present invention.

Regarding the contact hole pattern, it was confirmed that the 0.40 μm pattern which was not resolved by the conventional exposure was resolved with the focus margin of 1.3 μm by the mask of the present invention.

Note that the titanium oxide film can be applied to a g-line mask as shown in FIG. The g-line refractive index of titanium oxide whose elemental composition ratio is controlled is 2.30, and the image quality is deteriorated as compared with the current light shielding film. However, the deterioration as compared with the depth of focus when the film thickness is infinitely set to 0 is suppressed to within 10%, so that it is sufficiently applicable.

Further, it is impossible to apply KrF laser because both titanium and titanium dioxide have large extinction coefficients and almost shield light (FIG. 22).

(Embodiment 7) This embodiment is directed to a method of manufacturing the exposure mask of the third invention and the exposure mask of the fourth invention.
In particular, the present invention relates to an exposure mask when g-ray is used as an exposure light source and a method of manufacturing the same.

This exposure mask relates to a g-line projection exposure mask characterized by using an aluminum oxide pattern formed as a translucent pattern by controlling the composition ratio of oxygen by a sputtering method.

First, an aluminum oxide film is formed on a silicon oxide substrate by sputtering using aluminum as a target and adding a predetermined amount of a mixed gas of oxygen and argon. The refractive index of this aluminum oxide film with respect to the g-line was n = 1.56, and the thickness at which the phase difference was 180 ° was 390 nm. The amplitude transmittance at this time was 15% with respect to the amplitude transmittance of the silicon oxide substrate as the transparent portion (FIG. 23).

Then, in the same manner as in Example 3, a resist for electron beam was deposited to a thickness of 0.5 μm, and a conductive film was further formed to a thickness of 0.2 μm.
It is formed to about μm. Then, drawing is performed on the conductive film with an electron beam at 3 μC / cm ² , and development is performed to form a resist pattern. Using this resist pattern as a mask, the titanium oxide film exposed from the resist pattern is removed by chemical ion etching (CDE) using Cl ₂ gas. Finally, the resist pattern is immersed in a mixed solution of sulfuric acid and hydrogen peroxide to remove the resist pattern, thereby obtaining an aluminum oxide pattern.

In this example, an aluminum oxide film was formed as a phase shifter by sputtering using aluminum as a target. However, sputtering using a mixed target of aluminum and aluminum oxide whose area ratio was previously adjusted may be used. good. The thickness of the aluminum oxide film may be set to an appropriate thickness without departing from the scope of the present invention.

Further, the processing of the aluminum oxide film may be performed by anisotropic etching.

In the present invention, SiO _{2 is used} as the light-transmitting substrate.
It was used but may be used MgF _2, CaF _2, etc., instead of SiO _2.

In the present invention, the transmittance of the translucent film may be set to an appropriate value without departing from the scope of the present invention.
The optical characteristics of the translucent film can be finely adjusted by injecting ions such as arsenic, phosphorus, and boron into the translucent film or by applying heat.

When a substrate in which a conductive film is formed on a light-transmitting substrate is used instead of the SiO ₂ substrate, the coating conductive film is not required. When the mask pattern is drawn by light exposure, the conductive film can be eliminated.

Further, in this embodiment, electron beam is used for drawing at the time of making a mask, but light may be used instead of electron beam. When light is used, a photosensitive resin material and a conductive film provided over a light-transmitting substrate are not required.

Through the exposure mask formed in this way, a substrate called PFR7750 (manufactured by Nippon Synthetic Rubber Co., Ltd.) coated with 1.5 μm of resist was exposed to a 1/5 reduction exposure (NA = 0.54, σ = 0.5) to form a line & space pattern. The exposure required at this time was 300 mJ / cm ² . 0.45 with conventional exposure
What has been resolved with a focus margin of 0 μm in a pattern of μm is replaced by a mask of the present invention.
Resolution was possible at 4 μm.

Regarding the contact hole pattern, it was confirmed that the 0.50 μm pattern, which was not resolved by the conventional exposure, was resolved by the mask of the present invention with a focus margin of 0.8 μm.

When these depths of focus are compared with the depths of focus when exposing a mask made of a silicon film as a translucent film, the depth of focus is smaller in any of the line & space and contact hole patterns. This is because the translucent film pattern on the mask is 390 nm, which is very thick compared to 59 nm in the case of silicon, which causes deterioration in image quality.

When aluminum oxide is used as the translucent film, the refractive index is 2 or less at any wavelength from the g-line to the KrF laser, and the image quality cannot be reduced. In this case, aluminum oxide can be applied as a translucent film, but the effect as a phase shift mask cannot be obtained to the maximum (FIG. 23).

(Embodiment 8) FIG. 3 is a manufacturing process diagram for explaining the present embodiment.

First, an electron beam negative resist SAL601302 is applied at a thickness of 5000 angstroms on a silicon oxide substrate 301 of a thickness of 2.5 mm on which a light-shielding film of a thickness of 1000 angstroms made of chromium 312 and chromium oxide 313 is formed, and baked. (Fig. 3
(A)).

Further, a resist pattern 302a was formed by drawing and developing with an electron beam (FIG. 3).
(B)). Using this resist pattern as a mask, the exposed light-shielding film was removed by chlorine gas. Further, the light-shielding regions 313a / 312a were formed by removing the resist pattern 302a with a resist stripper and oxygen ashing. At this time, the light shielding film was arranged outside the desired pattern area (FIG. 3C).

Next, a semi-transparent amorphous silicon film 314 is formed on this substrate by sputtering by RF application (FIG. 3D). At this time, the thickness of the amorphous Si is 5
7 nm. When the g-line (436 nm) is used as an exposure light source in the wafer exposure process, the phase of light transmitted through the translucent film is 180 ° with respect to the phase of light transmitted through the transparent portion.
It is adjusted to shift. The substrate was coated with an electron beam negative resist SAL601304 at a thickness of 5000 Å, and a coatable conductive film 305 was formed (FIG. 3E). Further, a resist pattern 304a is formed by drawing and developing with an electron beam (FIG. 3 (f)).

Next, the exposed amorphous silicon film 314 is removed by performing chemical ion etching with CF4 gas using the resist pattern 304a as a mask (FIG. 3 (g)).

Finally, the desired translucent pattern 314a can be formed by removing the resist pattern 304a by immersing it in a resist stripper (FIG. 3).
(H)). Instead of chemical ion etching using CF ₄ above may be performed wet etching using NH4 F solution.

In this embodiment, a chromium film is used as the light-shielding film. However, the present invention is not limited to this, and a molybdenum silicide film or the like may be used.

In this embodiment, the conductive film is provided on the electron beam resist provided at the time of processing the translucent film. However, the conductive film may be provided on the silicon oxide substrate. Also, the material of the conductive film,
An organic conductive film may be used first, including a metal-containing material.

The present embodiment is a method of preparing a translucent film mask for g-line exposure. As a mask for i-line and KrF, a gas containing nitrogen or oxygen element is introduced during the sputtering of an amorphous Si film and reacted. (SiOα: 0 <
α <2, SiNβ: 0 <β <1.33), and a semi-transparent mask can be formed by a similar method after resist coating.

In the present invention, the film is formed by the sputtering method. However, the film can be formed by the CVD method, the vapor deposition method or the like.

In the above steps, the resist pattern is formed by electron beam lithography, but may be formed by UV exposure. In this case, it is not necessary to form a conductive resin film on the electron beam resist.

In the present invention, the light shielding film and the translucent film are laminated outside the pattern area.
If there is sufficient positional accuracy, the outside of the pattern area may be formed only by the light-shielding film.

(Embodiment 9) FIG. 4 is a manufacturing process diagram for explaining this embodiment.

First, a film having a thickness of 2.5 Å on which a conductive resin layer (mainly composed of SnO ₂ ) having a thickness of 200 Å was formed.
A semi-transparent amorphous Si film 402 is formed on a silicon oxide substrate 401 having a thickness of 2 mm by sputtering using RF (FIG. 4A). At this time, the film thickness of the amorphous Si is 57 nm, and when the g-line (436 nm) is used as an exposure light source in the wafer exposure process, the phase of the light transmitted through the translucent film is changed to the phase of the light transmitted through the transparent portion. Are adjusted so as to be shifted by 180 °. The substrate is coated with an electron beam negative resist SAL601403 at a thickness of 5000 Å, and baked (FIG. 4).
(B)).

Further, a resist pattern 403 is formed by drawing and developing with an electron beam (FIG. 4).
(C)). At this time, the drawing drawn five times larger than the design size is used.

Next, the exposed amorphous silicon film 402 is removed by performing chemical ion etching with CF ₄ gas using the resist pattern 403 as a mask.

Next, the amorphous silicon film 402 corresponding to the dimensional conversion difference of 0.3 μm (0.06 μm on the wafer), which is used as a secret when forming the mask, is removed by side etching by the same processing (FIG. 4D). . Note that this mask is created based on a 0.6 μm pattern.

Finally, the desired translucent film pattern 402 can be formed by removing the resist pattern 403 by immersing it in a mixed solution of sulfuric acid and hydrogen peroxide (FIG. 4E). Note that wet etching using an NH ₄ F aqueous solution may be performed instead of the chemical ion etching using CF ₄ .

In this embodiment, the conductive film is provided on the resist film. However, a conductive film may be provided on the interface between the silicon substrate and the translucent film. Further, as the material of the conductive film, an organic conductive film including a metal-containing material may be used.

In this embodiment, a method of forming a semi-transparent film mask for g-line exposure is used. For a mask for i-line and KrF, a gas containing nitrogen or oxygen element is introduced during the sputtering of an amorphous Si film and reacted. Film formation (SiOα: 0 <α <
2, SiNβ: 0 <β <1.33), and a semi-transparent mask can be formed by a similar method after resist coating.

In the present invention, the film is formed by the sputtering method, but may be formed by the CVD method, the vapor deposition method, or the like.

In the above steps, the resist pattern is formed by electron beam lithography, but may be formed by UV exposure. In this case, it is not necessary to form a conductive resin film on the transparent substrate. In the above process, a negative type resist is used. However, in order to use a positive type resist, data processing for forming a resist pattern larger than a dimensional conversion difference required in forming a mask is performed. Need to do.

In this embodiment, the resist pattern 40
3 as a mask, the lower amorphous silicon film 40
Etching 2 is performed by chemical dry etching. When the isotropic etching is performed as described above, the pattern to be etched has a tapered shape. The above-described amorphous silicon film corresponds to the translucent pattern of the translucent phase shift mask, and it has been confirmed by simulation and experiment that when the tapered shape is used, the precision of phase and amplitude transmittance adjustment is reduced.

Therefore, in the experimental example, the dimensional conversion difference is adjusted by side etching so that the accuracy and shape of the translucent film pattern with respect to the transfer pattern are improved at the same time. A transfer experiment to a wafer was actually performed using this mask, and as a result, a pattern with good dimensional accuracy and a good shape was obtained.

Example 10 First, a translucent amorphous Si film 502 was formed on a 2.5 mm-thick silicon oxide substrate 501 on which a 200 Å-thick conductive resin layer (mainly composed of SnO ₂ ) was formed. It is formed by sputtering by RF application (FIG. 5A). At this time, the film thickness of the amorphous Si is 57 nm, and when the g-line (436 nm) is used as an exposure light source in the wafer exposure process, the phase of the light transmitted through the translucent film is changed to the phase of the light transmitted through the transparent portion. Are adjusted so as to be shifted by 180 °. The substrate is coated with an electron beam negative resist SAL601503 with a film thickness of 5000 Å and baked (FIG. 5B).

Further, the resist pattern 503 is formed by drawing and developing with an electron beam (FIG. 5).
(C)). Data obtained by subtracting the dimension conversion difference 0.30 μm (0.06 μm on the wafer) required for mask formation from the design dimensions as the drawing data is created on a computer, and is further enlarged five times to this data. Was used. In this mask, a 0.6 μm pattern is considered as a reference.

Then, using the resist pattern 503 as a mask, the exposed amorphous Si film 502 is removed by anisotropic etching under magnetic field control using CF ₄ gas (FIG. 5D).

Finally, the resist pattern 503 is removed by dipping a mixed solution of sulfuric acid and hydrogen peroxide to form a desired translucent film pattern 502 (FIG. 5).
(E)).

In this embodiment, the conductive film is provided on the silicon substrate. However, the conductive film may be provided on the surface of the resist film or on the interface between the resist film and the translucent film. Also, the material of the conductive film,
An organic conductive film may be used first, including a metal.

In this embodiment, a method of forming a translucent film mask for g-line exposure is performed. As a mask for i-line and KrF, a gas containing nitrogen or oxygen element is introduced during the sputtering of an amorphous Si film, and the reaction is carried out. Film formation (SiOα: 0 <α
<2, SiNβ: 0 <β <1.33), and a semi-transparent mask can be formed by the same method after resist coating.

In the present invention, the film is formed by the sputtering method. However, the film can be formed by the CVD method, the vapor deposition method or the like.

In the above steps, the resist pattern is formed by electron beam lithography, but may be formed by UV exposure. In this case, it is not necessary to form a conductive resin film on the transparent substrate. In addition, since a negative resist is used in the above process, the drawing data is obtained by subtracting the dimension conversion difference required for mask formation from the design dimension and multiplying it by five. Is used, the data obtained by adding the dimensional conversion difference and multiplying by 5 may be used.

In the above process, a transparent substrate having a thickness of 2.5 mm is used.
In the case of 2 mm, even if RF control is performed from the lower part of the substrate during chemical dry etching using CF ₄ gas, RF is not sufficiently transmitted and plasma cannot be generated because SiO ₂ is an insulator. Therefore, a CF ₄ gas was introduced, and a plasma was formed by irradiating the CF ₄ gas with an electron beam, and an attempt was made to remove the exposed translucent film. In this method, the control of ions was controlled by the magnetic field of a magnet arranged inside the device.

In this embodiment, the resist pattern 5
Using the mask 03 as a mask, the underlying amorphous silicon film is etched by magnetic field controlled anisotropic etching. Therefore, when the isotropic etching is performed in the ninth embodiment, the pattern has a tapered shape. In the present embodiment, a vertical pattern shape is obtained. Therefore, by drawing using drawing data in which a dimensional conversion difference is incorporated in advance, it is possible to obtain a translucent pattern having an ideal phase and amplitude transmittance, in which a pattern having a desired size can be transferred.

A transfer experiment to a wafer was actually performed using this mask, and as a result, a pattern having good dimensional accuracy and a good shape was obtained.

[0238] (Example 11) 200 Å of film thickness of the conductive resin layer (SnO ₂ is the main component) thickness with an electron beam negative resist SAL601603 on the quartz substrate 601 having a thickness of 2.5mm was formed of 5000 Å And baked (FIG. 6).
(A)).

Next, a resist pattern 602 is formed by drawing and developing with an electron beam (FIG. 6B).
Here, the exposure amount is set to be smaller than the appropriate exposure amount (about 90% of the desired exposure amount) to form an inversely tapered resist pattern. Here, the resist pattern is formed to have an inverse tapered shape in order to prevent the amorphous silicon from being attached to the side wall of the resist at the time of sputtering film formation. At this time, data obtained by subtracting the dimension conversion difference 0.30 μm (0.06 μm on the wafer) required for mask formation from the design dimensions was created on a computer, and the data was further magnified five times. Use something. Note that this mask is created based on a 0.6 μm pattern.

Next, a semi-transparent film amorphous Si film 603
Was formed by sputtering by RF application (FIG. 6).
(C)). At this time, the thickness of the amorphous Si is 57 nm.
Met. This film thickness is adjusted so that the phase of light passing through the translucent film is shifted by 180 ° with respect to the phase of light passing through the transparent portion when g-ray (436 nm) is used as an exposure light source in the wafer exposure process. is there.

Next, a desired translucent film pattern 603 is formed by removing the resist with an organic solvent such as acetone and removing the resist pattern 602 by immersing the resist pattern 602 in a mixed solution of sulfuric acid and hydrogen peroxide. (Fig. 6
(E)).

In this embodiment, the conductive film is provided on the silicon oxide substrate. However, a conductive film may be provided on the surface of the resist film or on the interface between the resist film and the translucent film. Further, as the material of the conductive film, an organic conductive film including a metal-containing material may be used.

In this embodiment, a semi-transparent film mask for g-line exposure is prepared. For the mask for i-line and KrF, a gas containing nitrogen or oxygen element is introduced during the sputtering of the amorphous Si film and reacted. Film formation (SiOα: 0 <α <
2, SiNβ: 0 <β <1.33), and a semi-transparent mask can be formed by a similar method after resist coating.

In the present invention, the film is formed by the sputtering method. However, the film can be formed by the CVD method, the vapor deposition method or the like.

In the above steps, the resist pattern is formed by electron beam lithography, but may be formed by UV exposure.

In this embodiment, after a resist pattern having an inverse taper shape is formed, an amorphous silicon film is formed in a region other than the side wall of the resist pattern by sputtering. At this time, as the drawing data of the resist pattern, data incorporating a dimensional conversion difference is used. By removing the amorphous silicon layer, it is possible to obtain a translucent film pattern having an ideal phase and amplitude transmissivity on which a pattern having a desired dimension can be transferred.

Actually, a transfer experiment to a wafer was performed using this mask, and as a result, a pattern with good dimensional accuracy and a good shape was obtained.

(Example 12) A positive photoresist A for i-line was formed on a quartz (transparent) substrate 701 having a thickness of 2.5 mm.
Z-5214702 is applied in a film thickness of 5000 angstroms and baking is performed (FIG. 7A).

Next, drawing is performed using the i-line of a mercury lamp to obtain an exposed portion 702b and a non-exposed portion 702a (FIG. 7).
(B)). At this time, the drawing conversion from the design dimension to the dimension conversion difference of 0.30 μm (0.0
Data obtained by subtracting 6 μm) was created on a computer, and data obtained by magnifying the data 5 times was used. In this mask, a 0.6 μm pattern is created as a reference.

Next, baking is performed at 120 ° C. to make the exposed portion 702b an insoluble film, and then the entire surface of the substrate is exposed, so that the non-exposed portion 702a becomes a soluble film.

Next, development is performed to form an inversely tapered resist pattern 702 corresponding to the exposed portion 702b.
Here, the resist pattern is formed to have an inversely tapered shape in order to prevent the amorphous silicon from adhering to the side wall of the resist at the time of sputtering film formation (FIG. 7C).

Next, the semi-transparent film amorphous Si film 70
No. 3 was formed by sputtering by RF application (FIG. 7).
(D)). At this time, the thickness of the amorphous Si is 57 nm.
Met. This film thickness is adjusted so that the phase of light passing through the translucent film is shifted by 180 ° with respect to the phase of light passing through the transparent portion when g-ray (436 nm) is used as an exposure light source in the wafer exposure process. is there.

Next, the resist is removed with an organic solvent such as acetone, and the resist pattern 702 is removed by dipping in a mixed solution of sulfuric acid and hydrogen peroxide to form a desired translucent film pattern 703. (Figure 7)
(E)).

In this embodiment, the conductive film is provided on the silicon oxide substrate. However, the conductive film may be provided on the surface of the resist film or at the interface of the translucent film of the resist film. Further, as the material of the conductive film, an organic conductive film including a metal-containing material may be used.

In this embodiment, a method for forming a translucent film mask for g-line exposure is used. For a mask for i-line and KrF, a gas containing nitrogen or oxygen element is introduced during the sputtering of an amorphous Si film, and the mask is reacted. Film formation (SiOα: 0 <α <
2, SiNβ: 0 <β <1.33), and a semi-transparent mask can be formed by a similar method after resist coating.

In the present invention, the film is formed by the sputtering method. However, the film can be formed by the CVD method, the vapor deposition method or the like.

In the above steps, the resist pattern is formed by electron beam lithography, but may be formed by UV exposure.

In this embodiment, after a resist pattern having an inverted tapered shape is formed, an amorphous silicon film is formed by sputtering in a region other than the side wall of the resist pattern. At this time, as the drawing data of the resist pattern, data incorporating a dimensional conversion difference is used. By removing the amorphous silicon layer, it is possible to obtain a translucent film pattern having an ideal phase and amplitude transmissivity capable of transferring a pattern of a desired size.

Actually, a transfer experiment to a wafer was performed using this mask, and as a result, a pattern with good dimensional accuracy and good shape was obtained.

[0260]

As described above, according to the present invention, since the exposure mask can be formed of a single-layer film having an optimum optical constant, the control of the amplitude transmittance and the phase difference is easy, and By setting the refractive index of the layer film to a predetermined value or more, a highly reliable exposure mask equivalent to a light-shielding mask can be obtained.

[Brief description of the drawings]

FIG. 1 is a manufacturing process diagram of an exposure mask according to a first embodiment of the present invention.

FIG. 2 is a manufacturing process diagram of an exposure mask according to a third embodiment of the present invention.

FIG. 3 is a manufacturing process diagram of an exposure mask according to an eighth embodiment of the present invention.

FIG. 4 is a manufacturing process diagram of an exposure mask according to a ninth embodiment of the present invention.

FIG. 5 is a manufacturing process diagram of an exposure mask according to a tenth embodiment of the present invention.

FIG. 6 is a manufacturing process diagram of an exposure mask according to an eleventh embodiment of the present invention.

FIG. 7 is a manufacturing process diagram of an exposure mask according to a twelfth embodiment of the present invention.

FIG. 8 is a view showing a range of optical constants to be satisfied when a g-line translucent film pattern is formed of a single-layer Si film and actual measured values of the optical constants.

FIG. 9 is a view showing a range of optical constants to be satisfied when forming an i-line translucent film pattern with a single-layer SiNα film, and actual measured values of the optical constants.

FIG. 10 is a view showing a range of optical constants to be satisfied when forming a translucent film pattern for KrF with a single-layer SiNα film and actual measured values of the optical constants.

FIG. 11 is a view for explaining an optimum dimensional conversion difference.

FIG. 12 is a diagram illustrating a portion where image quality degradation occurs on a mask.

FIG. 13 is a view for explaining the relationship between the image quality degradation area and the depth of focus.

FIG. 14 is a diagram for explaining a refractive index for forming an image quality deteriorated region and a translucent film.

FIG. 15 is a diagram showing a range of optical constants to be satisfied when a g-line translucent film pattern is formed of a Ge single layer film and actual measured values of optical constants.

FIG. 16 is a view showing a range of optical constants to be satisfied when a g-line semi-transparent film pattern is formed of a GaAs single-layer film and actual measured values of the optical constants.

FIG. 17 is a view showing a range of optical constants to be satisfied when a semi-transparent film pattern for i-line is formed by a CrOε single layer film and actual measured values of the optical constants.

FIG. 18 is a diagram showing a range of optical constants to be satisfied when a g-line translucent film pattern is formed of a CrOε single layer film and actual measured values of the optical constants.

FIG. 19 is a view showing a range of optical constants to be satisfied when forming a translucent film pattern for KrF with a CrOε single-layer film and actually measured optical constants.

FIG. 20 is a diagram showing a range of optical constants to be satisfied when forming a translucent film pattern for i-line with a TiOδ single-layer film, and actual measured values of the optical constants.

FIG. 21 is a view showing a range of optical constants to be satisfied when a g-line translucent film pattern is formed of a TiOδ single-layer film and actual measured values of the optical constants.

FIG. 22 is a diagram showing a range of optical constants to be satisfied when a translucent film pattern for KrF is formed of a TiOδ single-layer film and actually measured optical constants.

FIG. 23 is a view showing a range of optical constants to be satisfied when a g-line translucent film pattern is formed of an AlOγ single-layer film and actual measured values of the optical constants.

FIG. 24 is a view showing a range of optical constants to be satisfied when an i-line translucent film pattern is formed of an AlOγ single-layer film and actual measured values of the optical constants.

FIG. 25 is a diagram showing a range of optical constants to be satisfied when a translucent film pattern for KrF is formed of an AlOγ single-layer film and actual measured values of the optical constants.

FIG. 26 is a view showing a conventional translucent phase shift mask.

FIG. 27 is a view showing a problem of a conventional translucent phase shift mask.

[Explanation of symbols]

101, 201, 301, 401, 501, 601, 7
01, 1101: silicon oxide substrate 102, 314, 402, 502, 603, 703: silicon film 103, 203, 302, 304, 403, 503, 6
02, 702: resists 104, 204, 305: coatable conductive film 202: silicon nitride film 303: inspection mark formed outside the pattern region 312: chromium film 313: chromium oxide film 1101a: light transmitting portion (phase = 0) 1101b: translucent phase shift portion 1102: transmittance adjusting film 1103: phase adjusting film 1105: defect generated in transmittance adjusting portion

Continued on the front page (72) Inventor Takashi Kamo 1 Tokoba, Komukai Toshiba-cho, Kawasaki City, Kanagawa Prefecture Inside the Toshiba R & D Center Co., Ltd. 2H095 BA01 BB03 BB06 BC05 F-term in Toshiba R & D Center (Reference)

Claims (6)

[Claims] An exposure mask comprising a translucent mask pattern formed on a translucent substrate such that a phase difference of an optical path length with respect to exposure light differs from a transparent portion by approximately 180 °. , The complex refractive index ni of the translucent film
An exposure mask, wherein a real part n of k (i: imaginary unit) is 2.03 or more. 2. An exposure mask including a translucent mask pattern formed on a translucent substrate such that a phase difference of an optical path length with respect to exposure light differs from a transparent portion by approximately 180 °. , The complex refractive index n-ik of the translucent film
The exposure mask, wherein the real part n of (i: imaginary unit) is equal to or greater than a value obtained by adding 1 after dividing the wavelength of light used for exposure by 240 nm. 3. An exposure mask including a translucent mask pattern formed on a translucent substrate such that a phase difference of an optical path length with respect to exposure light differs from a transparent portion by approximately 180 °. , The complex refractive index n-ik of the translucent film
An exposure mask, wherein an imaginary part k (extinction coefficient) of (i: imaginary unit) is a value of 0.4 or more. 4. The method of manufacturing an exposure mask according to claim 1, wherein an amplitude transmittance of the translucent film is adjusted in a range of 10% to 30%. 5. The method for manufacturing an exposure mask according to claim 1, wherein the translucent film is a single layer. 6. An exposure method comprising a step of exposing a wafer using the exposure mask according to claim 1. Description: