JP2019204137A - Method for designing and method for manufacturing photomask, and method for manufacturing display device - Google Patents

Abstract

To provide a photomask exhibiting excellent transfer property, with which a resist pattern in an advantageous shape can be formed upon transferring a pattern, a method for designing a photomask, a photomask blank, and a method for manufacturing a display device.SOLUTION: The photomask has a transfer pattern including a patterned phase shift film on a transparent substrate. The transfer pattern includes a phase shift portion where the phase shift film is formed on the transparent substrate, and a light-transmitting portion where the transparent substrate is exposed. Among a phase shift amount (degree) φto g-line, a phase shift amount (degree) φto h-line and a phase shift amount (degree) φto i-line of the phase shift mask, φ>φis satisfied and φis a closest value to 180 degrees among these φ, φand φ.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a photomask having a transfer pattern on a transparent substrate. In particular, the present invention relates to a photomask advantageous for manufacturing a display device, a method for designing the photomask, a photomask blank for manufacturing the photomask, and a method for manufacturing a display device using the photomask.

  According to Patent Document 1, it is proposed to use a photomask obtained by sequentially etching a phase inversion film and a light shielding film pattern for manufacturing an FPD (flat panel display) device.

  Here, in order to increase the resolution of a pattern in a photomask used for manufacturing an FPD device, if the wavelength of the light source is shortened and the lens is enlarged, the focal depth of the lens is reduced and a practical pattern resolution is obtained. Is related to the problem of limitations, and a photomask having a phase inversion film is described. The phase difference deviation of the phase inversion film with respect to the i-line, h-line, and g-line is desirably 10 ° or less.

JP 2012-230379 A

  At present, display devices including liquid crystal display devices, EL display devices, and the like are desired to be brighter and save power, and to improve display performance such as high definition, high speed display, and wide viewing angle.

  For example, in the case of a thin film transistor (“TFT”) used in the display device, contact holes formed in an interlayer insulating film among a plurality of patterns constituting a TFT substrate are surely formed in an upper layer and a lower layer. If there is no action to connect the patterns, correct operation cannot be guaranteed. On the other hand, in order to increase the aperture ratio of the display device as much as possible to obtain a bright and power-saving display device, the diameter of the contact hole is required to be sufficiently small. Accordingly, it is desired that the diameter of the hole pattern provided in the photomask for forming such a contact hole is also reduced (for example, less than 4 μm). For example, a hole pattern with a diameter of 2.5 μm or less and further with a diameter of 2.0 μm or less is required, and in the near future, formation of a pattern with a diameter of 1.5 μm or less, which is less than this, is considered desirable. In view of this background, there is a need for a display device manufacturing technique that enables reliable transfer of minute contact holes.

  In the field of lithography for manufacturing display devices, the NA (numerical aperture) of an exposure apparatus known as LCD (or FPD) is about 0.08 to 0.10, and the exposure light source is i-line, h-line, In many cases, the broad wavelength region including g-line is used, realizing high production efficiency and advantageous cost.

  However, in the lithography field for manufacturing display devices as described above, there is an increasing demand for pattern miniaturization. The present inventor has attempted to solve the problem of stably manufacturing a finer display device without deteriorating productivity and cost.

  In Patent Document 1, when a phase inversion film is used for a photomask pattern, it is utilized that the resolution is increased by the cancellation interference of exposure light at the boundary of the phase inversion film. The phase inversion film is preferably formed so that the phase difference with respect to i-line, h-line, and g-line is close to 180 °, but the phase difference is unavoidably different depending on the wavelength. It is desirable to make the deviation as small as possible. In this case, the phase difference of the phase inversion film may be set to 180 ° for any wavelength of exposure light.

  However, in order to make the phase difference deviation as small as possible, it is necessary to develop a film material having such physical properties, and it is not easy to search for the material.

  Therefore, the present invention has an object to obtain a photomask that can form a resist pattern having an advantageous shape during pattern transfer and exhibits excellent transferability. The present invention has been completed by intensively studying the problem of finding a photomask that enables transfer with excellent resolution even when a film material having a phase difference deviation is used.

Configuration 1 of the present invention is a photomask provided with a transfer pattern including a patterned phase shift film on a transparent substrate,
The transfer pattern includes a phase shift portion in which a phase shift film is formed on the transparent substrate, and a translucent portion where the transparent substrate is exposed,
The phase shift amount (degree) with respect to the g line of the phase shift film is φ _g ,
The possessed by the phase shift film, the amount of phase shift (in degrees) and phi _h for h line,
When the phase shift amount (degree) with respect to i line of the phase shift film is φ _i ,
φ _i > φ _g
In addition, among these φ _g , φ _h , and φ _i , the photo mask having a value closest to 180 degrees is φ _g .

Configuration 2 of the present invention is the photomask according to Configuration 1, wherein 3 <T _g <15, where T _g (%) is the transmittance for g-line of the phase shift film. .

Configuration 3 of the present invention, the phase shift film has a transmittance for the g-line and T _{g (%),} when the transmittance of i-line and T _{i (%),}
T _i <T _g
It is a photomask of the structure 1 or 2 characterized by being.

  Configuration 4 of the present invention is the photomask according to any one of Configurations 1 to 3, wherein the transfer pattern includes an isolated hole pattern having a diameter of 4 μm or less.

  Configuration 5 of the present invention is the photomask according to any one of Configurations 1 to 4, wherein the photomask is a photomask that applies light including an i-line to g-line wavelength range as exposure light.

  Configuration 6 of the present invention is any one of the photomasks 1 to 5 further including a patterned light-shielding film on the transparent substrate.

  The structure 7 of this invention is a photomask in any one of the structures 1-6 with which the said photomask is provided with the pattern for a transfer for display apparatus manufacture.

Configuration 8 of the present invention is a photomask blank in which a phase shift film is formed on a transparent substrate, and a photomask for forming a transfer pattern by patterning the phase shift film to form a photomask In the blank
The phase shift amount (degree) with respect to the g line of the phase shift film is φ _g ,
The possessed by the phase shift film, the amount of phase shift (in degrees) and phi _h for h line,
When the phase shift amount (degree) with respect to i line of the phase shift film is φ _i ,
φ _i > φ _g
Among these φ _g , φ _h , and φ _i , the photo mask blank is characterized in that φ _g is the closest value to 180 degrees.

Configuration 9 of the present invention is the photomask blank according to Configuration 8, wherein 3 <T _g <15, where T _g (%) is the transmittance for g-line of the phase shift film.

In the configuration 10 of the present invention, when the transmittance of the phase shift film with respect to g-line is T _g (%) and the transmittance with respect to i-line is T _i (%),
T _i <T _g
It is the photomask blank of the structure 8 or 9 characterized by the above-mentioned.

  Configuration 11 of the present invention is a photomask blank for manufacturing a photomask that applies light including an i-line to g-line wavelength range as exposure light, and is any one of configurations 8 to 10 One photomask blank.

  The structure 12 of the present invention is any one of the photomask blanks 8 to 11 in which a light-shielding film is further formed on the phase shift film.

Configuration 13 of the present invention includes a step of preparing the photomask blank according to any one of Configurations 8 to 12,
Forming a transfer pattern by patterning the phase shift film of the photomask blank.

Configuration 14 of the present invention is a photomask design method comprising a transfer pattern including a patterned phase shift film on a transparent substrate,
The photomask is for transferring the transfer pattern to a transfer object with exposure light having intensity peaks at a plurality of wavelengths.
The transfer pattern includes a phase shift portion in which a phase shift film is formed on the transparent substrate, and a translucent portion where the transparent substrate is exposed,
When the transmittance of the phase shift film with respect to g-line is T _g (%),
3 <T _g <15
And
Of the plurality of wavelengths, the wavelength of the light on the longest wavelength side is α, and among the plurality of wavelengths, an arbitrary wavelength on the shorter wavelength side than α is β,
The phase shift amount of the phase shift film in the wavelength alpha and phi _alpha, the phase shift amount of the phase shift film in the wavelength beta when the phi _beta,
φ _β > φ _α
Meet, and the phi _alpha, rather than phi _beta in the arbitrary beta, so that the difference between 180 degrees smaller, and selects the physical properties and thickness of the phase shift film, photo This is a mask design method.

Configuration 15 of the present invention is a method for manufacturing a display device including a step of transferring a transfer pattern of a photomask onto a transfer target using an exposure device, wherein the transfer step includes a plurality of steps. In the method for manufacturing a display device, comprising irradiating the transfer pattern with exposure light including an intensity peak at a wavelength,
The photomask includes a transfer pattern in which a phase shift film is patterned on a transparent substrate,
The transfer pattern includes a phase shift portion in which a phase shift film is formed on the transparent substrate, and a translucent portion where the transparent substrate is exposed,
When the transmittance of the phase shift film with respect to g-line is T _g (%),
3 <T _g <15
And
Of the plurality of wavelengths, the wavelength of the light on the longest wavelength side is α, and among the plurality of wavelengths, an arbitrary wavelength on the shorter wavelength side than α is β,
The phase shift amount of the phase shift film in the wavelength alpha and phi _alpha, the phase shift amount of the phase shift film in the wavelength beta when the phi _beta,
φ _β > φ _α
The filled, and the phi _alpha, rather than phi _beta in the arbitrary beta, using the phase shift film having physical properties and thickness as the difference decreases between 180 degrees, the transfer pattern is formed A method for manufacturing a display device.

  According to the present invention, a resist pattern having an advantageous shape can be formed during pattern transfer, and a photomask exhibiting excellent transferability can be obtained.

It is a figure which shows the cross section of the resist film to which the hole pattern was transferred, and the photomask used for the transfer of the hole pattern. It is a light intensity curve at the time of exposing to the hole pattern of the photomask shown in FIG. It is a graph which shows the change of ILS and contrast according to the thickness of a phase shift film, and the phase shift amount in the thickness. It is a graph which shows the change of ILS according to the thickness of a phase shift film, and the transmittance | permeability in the thickness, and contrast.

  The photomask of the present invention is a photomask provided with a transfer pattern including a patterned phase shift film on a transparent substrate. The transfer pattern includes a phase shift portion in which a phase shift film is formed on the transparent substrate, and a translucent portion from which the transparent substrate is exposed.

Furthermore,
The phase shift amount (degree) with respect to the g line of the phase shift film is φ _g ,
The possessed by the phase shift film, the amount of phase shift (in degrees) and phi _h for h line,
When the phase shift amount (degree) with respect to i line of the phase shift film is φ _i ,
φ _i > φ _g
Met, and they phi _g, phi _h, in the phi _i, which is what the value closest to 180 degrees phi _g. In the present application, “the value closest to 180 degrees” includes a case where the value is equal to 180 degrees.

  As the transparent substrate used in the photomask of the present invention, a transparent material such as glass that is polished flat and smooth can be used. As a photomask for manufacturing a display device, the main surface is preferably a quadrangle having a side of 300 mm or more.

  The transfer pattern included in the photomask of the present invention includes a phase shift portion in which a phase shift film is formed on a transparent substrate, and a light transmitting portion in which the surface of the transparent substrate is exposed.

Such a photomask (also referred to as a phase shift mask) inverts the phase of light transmitted through the phase shift unit (shifted by 180 degrees) and causes the phase shift unit and the translucent unit by the interference action of the light having the opposite phase. Reduce the light intensity near the boundary. Then, the resolution is increased by influencing the light intensity distribution received by the transfer target. If the transmittance T (%) of the exposure light possessed by the phase shift portion is too low, the effect of improving the resolution by the phase shift portion is reduced, and if it is too high, loss of resist thickness described later tends to become remarkable. is there. Considering these points, it is preferable that 3 <T <15. For example, when using a phase shift film whose transmittance for g-line is T _g (%), 3 <T _g <15.

  On the other hand, in an exposure apparatus used for manufacturing a display device, exposure light including a plurality of wavelengths (also referred to as broad wavelength light) is used. For example, exposure light using an ultra-high pressure mercury lamp having a peak in i-line (wavelength 365 nm), h-line (wavelength 405 nm), and g-line (wavelength 436 nm) as a light source is used. Exposure can be performed efficiently.

However, in a situation where a plurality of wavelengths are included in the exposure light, it is possible to accurately invert the phase (that is, to shift the phase by 180 degrees) for any of these wavelengths. It is difficult in a phase shift mask having Therefore, even if it is considered that the phase shift amount varies depending on the wavelength of light in the phase shift film (specifically, even if φ _i > φ _g as described above), excellent transferability is obtained. It is advantageous to obtain a photomask with.

In the present invention, when the transmittance for g of the phase shift film is T _g (%) and the transmittance for i-line is T _i (%),
T _i <T _g
It is preferable that There are excellent phase shift film materials that satisfy these conditions.

More preferably, when the transmittance of the phase shift film with respect to h-line is T _h (%),
T _i <T _h <T _g
It is.

  The inventor has studied a method for transferring a fine pattern with sufficient CD accuracy and stability using such a material.

In the photomask of the present invention,
The phase shift amount (degree) with respect to the g line of the phase shift film is φ _g ,
The possessed by the phase shift film, the amount of phase shift (in degrees) and phi _h for h line,
When the phase shift amount (degree) with respect to i line of the phase shift film is φ _i ,
These φ _g, φ _h, in the phi _i, what becomes a value closest to 180 ° is phi _g. As described above, “the value closest to 180 degrees” includes a case where the value is equal to 180 degrees.

  That is, the photomask of the present invention has a phase shift effect of 180 degrees or closer to the g-line on the longest wavelength side among the i-line, h-line, and g-line than the i-line and h-line. Has a phase shift film. In other words, in a photomask for exposure using broad wavelength light, 180 degrees with reference to the wavelength on the long wavelength side (here, the g-line that is the longest wavelength among the peaks of the exposure light). It has been found that it is advantageous to design the photomask to have a phase shift amount that is the closest to it.

  Hereinafter, the case where exposure light having peaks in the wavelengths of i-line, h-line, and g-line is used as the broad wavelength light will be described as an example.

  The i-line has the shortest wavelength among these three wavelengths. Considering that the higher resolution is expected if the wavelength is sufficiently short for the fine dimension part of the transfer pattern, the photomask film design should be based on i-line of the above three wavelengths. It is possible to do it. That is, it is a method of manufacturing a phase shift mask using a phase shift film showing a phase shift closest to 180 degrees with respect to the i-line wavelength (365 nm). In this case, in the g-line farthest from the i-line, the phase shift amount is considerably different from 180 degrees (for example, 150 to 160 degrees), so that the phase shift effect on the g-line is expected to be reduced. In order to avoid this, a design in which the phase shift amount is closest to 180 degrees with respect to the h-line located substantially in the center among these three wavelengths is also conceivable. However, it has never been verified how the mask design including the above actually affects transferability.

  In the manufacturing process of a display device, a transfer pattern of a photomask is transferred to a resist film (for example, a positive photoresist film) applied and formed on a transfer target (for example, a display substrate), and after development, A resist pattern is obtained. Then, the thin film included in the transfer object is etched. At this time, it is clear that the quality of the resist pattern greatly affects the etching accuracy.

  For example, if a small hole pattern is to be transferred to the resist film formed on the transfer target, the resolution becomes difficult as the hole diameter decreases. Therefore, when a phase shift mask is used to transfer the resist, a resist damage that causes a loss of the thickness of the resist film around the hole occurs in the formed resist pattern as the amount of light to be irradiated increases. As a reference example, FIGS. 1A and 1B show simulation results showing this situation. Here, FIG. 1A shows a cross section of a resist pattern formed on the resist film 30 when the phase shift mask shown in FIG. 1C is exposed by an FPD exposure apparatus, and FIG. 2 shows a cross section of a resist pattern formed on a resist film 30 when the phase shift mask shown in FIG. 1D is exposed by an FPD exposure apparatus.

Further, the phase shift masks shown in FIGS. 1C and 1D are obtained by forming a square isolated hole pattern 20 on the phase shift film 10 having a transmittance T _i of 5% with respect to i-line. The diameter of the isolated hole pattern in the photomask shown in c) (here, the length of one piece of the isolated hole pattern 20) is 3.0 μm, and the diameter of the isolated hole pattern in the photomask shown in FIG. 1D is 2.5 μm. is there.

  The resist pattern having an excellent shape for functioning as an etching mask is advantageous in that the edge is inclined (the angle θ shown in FIG. 1B is as vertical as possible). Stable etching accuracy is obtained, and excellent dimensional accuracy is obtained as a result. However, as shown in FIG. 1B, when the pattern diameter becomes smaller, θ becomes smaller and the inclination (falling) tends to become remarkable.

  Further, in the resist remaining film portion, it is advantageous that a resist having a sufficient thickness remains. In FIG. 1B having a small diameter, the thickness is smaller than that in FIG. Since the phase shift film has a predetermined light transmittance, the light intensity decreases due to light interference in the vicinity of the edge, but a so-called side lobe is generated at a distance from the edge. As a result, there is a demerit that impairs the thickness of the resist residual film. In particular, in the transmitted light intensity distribution, in the vicinity of the position where the side lobe occurs, the resist is depressed, and the amount of the remaining film takes a minimum value (point B in FIG. 1B).

  Therefore, the minimum portion of the residual film thickness of the resist, that is, the end portion of the resist pattern (point A in FIG. 1B, hereinafter also referred to as edge position) and the above-described resist recess position (point B in FIG. It is desired that the difference in height (also referred to as side lobe position) (H in FIG. 1B) is large.

  From the above, it can be seen that it is meaningful to evaluate the quality of the resist pattern shape based on the inclination θ of the edge of the resist pattern and the thickness H of the minimum resist residual film. The index to evaluate this can be ILS (Image Log-Slope) and contrast (Michelson Contrast), considering the optical image formed by the light transmitted through the photomask. Is considered advantageous. This can be expressed by the following parameters with reference to the transmitted light intensity curve shown in FIG. FIG. 2 is a light intensity curve as an optical image formed when the pattern shown in FIGS. 1C and 1D is exposed, in which A ′ is an edge position and B ′ is a side lobe. Each corresponds to a position.

here,
I (X _edge ) is the light intensity at the position X _edge corresponding to the edge position of the pattern in the light intensity distribution,
I (X _sidelobe ) is the light intensity at the position X _sidelobe corresponding to the side lobe position in the light intensity distribution.

  FIG. 3 shows a phase shift film when a phase shift mask having an isolated hole pattern with a diameter of 3 μm is used and transferred to a positive photoresist applied on a transfer medium under the same exposure conditions as those in FIG. Simulation results showing how ILS (left vertical axis) and contrast (right vertical axis) change according to thickness change (upper horizontal axis) and phase shift amount (lower horizontal axis) linked to it Indicates.

  The conditions applied in this simulation are that the NA (numerical aperture) of the optical system of the exposure apparatus is 0.083, σ (coherence factor) is 0.7, and the phase shift film contains MoSi. This phase shift film has a positive correlation between the transmittance and the wavelength within the wavelength range of the exposure light.

  On the lower horizontal axis, the film thicknesses of the phase shift film used for the phase shift exactly 180 degrees with respect to the i-line (365 nm), h-line (405 nm), and g-line (436 nm) are L, M, Indicated as N. That is, if this phase shift film is used as the film thickness L, it is a phase shift film based on the i-line, if used as the film thickness M, it is a phase shift film based on the h line, and if used as the film thickness N, it is based on the g line. It is a phase shift film.

  As understood from FIG. 3, in the ILS, the maximum value is shown when the h-line is used, and the value gradually decreases when the i-line and the g-line are used. On the other hand, since the contrast monotonously increases in this wavelength range, the highest value is shown on the maximum wavelength side. That is, when the wavelength is shortened, it rapidly decreases.

  Considering only the ILS, that is, the edge inclination shape of the resist pattern to be formed, it is considered best to apply a film (hereinafter referred to as an h-line reference shift film) that is phase-shifted by 180 degrees with respect to the h-line. However, considering both the contrast, that is, the influence of resist loss around the target pattern, it is more advantageous to select a film thickness of 180 degrees for the g-line (a g-line reference shift film). It became clear that there was. This is because the g-line reference shift film is slightly inferior in ILS to the h-line reference shift film, but can enjoy advantages over it in contrast. In fact, the mask using the g-line reference phase shift film illustrated in FIG. 3 showed excellent transferability such that the contrast was 0.6 or more while the ILS had a value of 1.50 or more.

  In order to examine the transmittance of the phase shift mask, FIG. 4 shows the transmittance of the phase shift film on the horizontal axis.

According to this, the transmittance T _g the g-line is at 3% to 15% of the region, the balance of the ILS and contrast can be understood that it is preferred. More preferred transmittance The _{T g} is 3-10%.

In the present invention, a phase shift film having a positive correlation with the transmittance with respect to the wavelength can be applied. However, the transmittance T _g (%) for g-line and the transmittance T _i (%) for i-line Between
3 ≦ T _g −T _i ≦ 10
Can be established.

More preferably,
4 ≦ T _g −T _i ≦ 9

Further, as a phase shift characteristic of the phase shift film applicable to the present invention, between the phase shift amount φ _g (deg) with respect to the g line and the phase shift amount φ _i (deg) with respect to the i line,
15 ≦ φ _i −φ _g ≦ 40
This is a preferable example.

More specifically,
20 ≦ φ _i −φ _g ≦ 35
It is.

  In the present invention, the phase shift amount is expressed in degrees (deg). For example, when the phase shift amount φ is 150 degrees, the phase of light is on the plus side or on the minus side [ A case of shifting by 150 + 360 × (n−1)] degrees is shown. Here, n represents a natural number.

In the phase shift film of the present invention, φ _g is closer to 180 degrees than φ _i and φ _h . φ _g may be equal to 180 degrees, or may not be equal and may be within a predetermined difference range. Preferably, the difference between _φg and 180 degrees is 30 degrees or less, more preferably 20 degrees or less, and even more preferably 10 degrees or less.

As the amount of phase shift for each wavelength,
150 <φ _g <210
And,
180 <φ _i <240
Is preferred.

In addition, when the phase shift amount with respect to the h line is φ _h (deg),
160 <φ _h <220
The case where is satisfied is illustrated.

Further, preferably 190 <φ _i <230
175 <φ _h <215
160 <φ _g <200

  Further, as understood from the above, the photomask of the present invention has a remarkable effect as a photomask using a wavelength region including i-line, h-line, and g-line as exposure light.

  The material of the phase shift film of the present invention can be, for example, a film containing Si, Cr, Ta, Zr, etc., and an appropriate material can be selected from these oxides, nitrides, carbides, and the like. . As the Si-containing film, a Si compound (SiON or the like), a transition metal silicide (MoSi or the like), or a compound thereof can be used. Examples of the MoSi compound include MoSi oxide, nitride, oxynitride, oxynitride carbide, and the like.

  When the phase shift film is a Cr-containing film, a Cr compound (oxide, nitride, carbide, oxynitride, carbonitride, oxynitride carbide) can be used.

  Of course, the photomask of the present invention may have a film other than the phase shift film or a film pattern as long as the effects of the present invention are not impaired. Examples thereof include a light shielding film, an etching stopper film, an antireflection film, and a charge adjustment film. In that case, it is preferable that the film in contact with the phase shift film of the present invention is made of a material having etching selectivity with the phase shift film. The material candidate can be selected from the materials listed for the phase shift film.

  There is no restriction | limiting in particular in the use of the photomask of this invention. However, the transfer pattern is particularly advantageous when it has fine dimensions.

  For example, the transfer pattern includes an isolated hole pattern with a diameter of 4 μm or less. In the case of an isolated hole pattern of preferably less than 3.5 μm, more preferably less than 3 μm, and even more preferably less than 2.5 μm, the effect of the invention is remarkable. As can be understood from FIG. 1 described above, patterns having a diameter of 2 μm or less are also used in future display devices, and the present invention can be applied to such patterns.

  Here, the diameter of the pattern is the diameter if the pattern is a circle, the length of one side if it is a square, the diameter of a circumscribed circle if it is another regular polygon, and the length of the short side if it is a rectangle. can do.

  Here, the “iso” pattern means the following. That is, when a pattern in which a plurality of patterns are regularly arranged to form a transfer image by optically acting on each other by interference of transmitted light is referred to as a dense pattern, the other pattern is used.

  More preferably, when one isolated pattern has a diameter of D μm, there is no other pattern within a distance range of at least 2D from the outer edge of the pattern. For example, when the D μm translucent part is an isolated pattern surrounded by the phase shift part, there is an example in which only the phase shift part exists in the range of a distance of at least 2D from the outer edge of the translucent part. Is done. Preferably, the other pattern does not exist in the 3D range.

  The hole pattern may be a “extract” (opening) pattern formed in the phase shift film.

  The hole pattern as described above can be a pattern for forming a contact hole in the display device to be obtained, but is not limited to this application.

  The transfer pattern provided in the photomask of the present invention can be transferred to a resist film on a transfer object to form a resist pattern having a good shape. This resist film may be a photoresist film. it can. There is no limitation on the positive type and the negative type, but the case of the positive type is preferable. In general, a photoresist used for manufacturing a display device is suitable for exposure using a high-pressure mercury lamp as a light source, and has sensitivity in the wavelength range of i-line, h-line, and g-line, and higher and lower wavelength sides. The sensitivity decreases.

  In the above, the superiority of the phase shift film based on the g-line has been described. When claiming the mask, it is advantageous that the phase shift amount is closer to 180 degrees with respect to the wavelength on the long wavelength side included in the exposure light than for the other wavelengths. In this case, the effect of the present invention can be obtained. The present invention includes such a photomask design method.

  The photomask of the present invention may further have a light shielding film pattern obtained by patterning a light shielding film. In this case, the light shielding film pattern may be a part of the transfer pattern or may be outside the area of the transfer pattern. In the former case, the transfer pattern may include a light-shielding portion in which a phase shift film and a light-shielding film are formed in addition to the light-transmitting portion and the phase shift portion. In the latter case, it may be a mark pattern for product identification or an alignment pattern used during photomask manufacturing or use.

  Although the use of the photomask of the present invention is not limited as described above, excellent effects can be obtained in display devices (including those known as LCD and OLED).

The present invention includes a photomask blank that can be used to obtain the photomask. This photomask blank
In a photomask blank in which a phase shift film is formed on a transparent substrate, and a pattern for transfer is formed by patterning the phase shift film to form a photomask,
The phase shift amount (degree) with respect to the g line of the phase shift film is φ _g ,
The possessed by the phase shift film, the amount of phase shift (in degrees) and phi _h for h line,
When the phase shift amount (degree) with respect to i line of the phase shift film is φ _i ,
φ _i > φ _g
Met, and they phi _g, phi _h, in the phi _i, which is what the value closest to 180 degrees phi _g. Note that “the value closest to 180 degrees” includes the case where it is equal to 180 degrees.

When the transmittance of the phase shift film with respect to g-line is T _g (%) and the transmittance with respect to i-line is T _i (%),
T _i <T _g
It is preferable that

  The characteristics of the phase shift film are as described above.

  The present invention also includes a photomask manufacturing method in which the photomask blank is prepared, and a phase shift film provided in the photomask blank is patterned to form a transfer pattern.

The present invention also includes a photomask design method. That is,
A photomask design method comprising a transfer pattern including a patterned phase shift film on a transparent substrate,
The photomask is for transferring the transfer pattern to a transfer object with exposure light having intensity peaks at a plurality of wavelengths.
The transfer pattern includes a phase shift portion in which a phase shift film is formed on the transparent substrate, and a translucent portion where the transparent substrate is exposed,
When the transmittance for g-line of the phase shift film is T _g (%),
3 <T _g <15
And
Of the plurality of wavelengths, the wavelength of the light on the longest wavelength side is α,
When the phase shift amount of the phase shift film in the wavelength alpha and phi _alpha,
The phi _alpha is also the phase shift amount in the wavelength other than alpha among the plurality of wavelengths, such that the difference between the 180-degree decreases, and determines the physical properties and thickness of the phase shift film,
This is a photomask design method.

Here, the plurality of wavelengths are included in the sensitivity region of the resist used when the photomask is exposed. Also here, the characteristics of the phase shift film are the same as those described above.
For example, the phase shift film may have a positive correlation between the wavelength and the light transmittance in the multiple wavelength region.

  The photomask designed by the design method of the present invention can be manufactured by applying a known process. That is, a phase shift film is formed on a transparent substrate by a film formation method such as sputtering, and a resist film is formed on the surface to prepare a photomask blank with resist. The resist can be a positive or negative photoresist, for example, a positive type. A desired pattern is drawn on the photomask blank using a drawing apparatus. As the drawing apparatus used here, a laser drawing apparatus or the like can be used. Next, the resist is developed with a known developer, and the phase shift film is etched using the formed resist pattern as a mask. Etching may be dry etching or wet etching, but wet etching is more preferable as a photomask for manufacturing a display device. This is because the etching is relatively easy for a substrate having a large size and various sizes. After the etching, the resist pattern is removed, and the photomask on which the phase shift film transfer pattern is formed is completed. Depending on the use of the photomask, in addition to the above-described steps, a light-shielding film or other film forming, drawing, and patterning steps may be added by a known method to form a transfer pattern to be obtained. .

Furthermore, the present invention includes a method for manufacturing a display device using the photomask.
That is,
A method for manufacturing a display device, comprising a step of transferring a transfer pattern of a photomask onto an object to be transferred using an exposure device, wherein the transfer step includes an exposure including intensity peaks at a plurality of wavelengths. In the method for manufacturing a display device, including irradiating the transfer pattern with light,
The photomask includes a transfer pattern in which a phase shift film is patterned on a transparent substrate,
The transfer pattern includes a phase shift portion in which a phase shift film is formed on the transparent substrate, and a translucent portion where the transparent substrate is exposed,
When the transmittance of the phase shift film with respect to g-line is T _g (%),
3 <T _g <15
And
Of the plurality of wavelengths, the wavelength of the light on the longest wavelength side is α,
When the phase shift amount of the phase shift film in the wavelength alpha and phi _alpha,
Wherein phi _alpha is also the phase shift amount in the wavelength other than alpha among the plurality of wavelengths, by using a phase shift film having physical properties and thickness as the difference decreases between 180 degrees, the transfer pattern is formed A method for manufacturing a display device.

  Here too, the plurality of wavelengths are included in the sensitivity region of the resist used during exposure of the photomask. In addition, as an exposure apparatus used here, the same-exposure exposure provided with an optical system having a numerical aperture (NA) of 0.08 to 0.15 and a coherence factor (σ) of about 0.5 to 1.0. A device is preferably used.

  Regarding the transferability of a photomask that is exposed using light in a broad wavelength region such as i-line to g-line, it is advantageous to set a 180-degree phase shift based on the wavelength on the longest wavelength side. It was an effect that exceeded expectations.

In the photomask exposure is performed using an i-line and h-line only, it is preferably close to phi _h Gayori 180 degrees out of phase shift phi _i and phi _h.

10 phase shift film 20 isolated hole pattern 30 resist film

Claims (15)

A photomask having a transfer pattern including a patterned phase shift film on a transparent substrate,
The transfer pattern includes a phase shift portion in which a phase shift film is formed on the transparent substrate, and a translucent portion where the transparent substrate is exposed,
The phase shift amount (degree) with respect to the g line of the phase shift film is φ _g ,
The possessed by the phase shift film, the amount of phase shift (in degrees) and phi _h for h line,
When the phase shift amount (degree) with respect to i line of the phase shift film is φ _i ,
φ _i > φ _g
And a photomask having a value closest to 180 degrees among φ _g , φ _h , and φ _i is φ _g . 2. The photomask according to claim 1, wherein 3 <T _g <15, where T _g (%) is a transmittance with respect to g-line of the phase shift film. When the transmittance of the phase shift film with respect to g-line is T _g (%) and the transmittance with respect to i-line is T _i (%),
T _i <T _g
The photomask according to claim 1, wherein the photomask is a photomask.   The photomask according to claim 1, wherein the transfer pattern includes an isolated hole pattern having a diameter of 4 μm or less.   The said photomask is a photomask of any one of Claims 1-4 which is a photomask which applies the light containing the wavelength range of i line | wire-g line | wire as exposure light.   The photomask according to claim 1, further comprising a patterned light-shielding film on the transparent substrate.   The photomask according to claim 1, wherein the photomask includes a transfer pattern for manufacturing a display device. In a photomask blank in which a phase shift film is formed on a transparent substrate, and a pattern for transfer is formed by patterning the phase shift film to form a photomask,
The phase shift amount (degree) with respect to the g line of the phase shift film is φ _g ,
The possessed by the phase shift film, the amount of phase shift (in degrees) and phi _h for h line,
When the phase shift amount (degree) with respect to i line of the phase shift film is φ _i ,
φ _i > φ _g
The filled, and they phi _g, phi _h, in the phi _i, a photomask blank, characterized in that what the value closest to 180 ° is phi _g. 9. The photomask blank according to claim 8, wherein 3 <T _g <15, where T _g (%) is a transmittance with respect to g-line of the phase shift film. When the transmittance of the phase shift film with respect to g-line is T _g (%) and the transmittance with respect to i-line is T _i (%),
T _i <T _g
The photomask blank according to claim 8 or 9, wherein   11. The photo according to claim 8, which is a photomask blank for manufacturing a photomask that applies light including a wavelength range of i-line to g-line as exposure light. Mask blank.   The photomask blank according to any one of claims 8 to 11, wherein a light shielding film is further formed on the phase shift film. A step of preparing the photomask blank according to any one of claims 8 to 12,
Forming a transfer pattern by patterning the phase shift film of the photomask blank. A photomask design method comprising a transfer pattern including a patterned phase shift film on a transparent substrate,
The photomask is for transferring the transfer pattern to a transfer object with exposure light having intensity peaks at a plurality of wavelengths.
The transfer pattern includes a phase shift portion in which a phase shift film is formed on the transparent substrate, and a translucent portion where the transparent substrate is exposed,
When the transmittance of the phase shift film with respect to g-line is T _g (%),
3 <T _g <15
And
Of the plurality of wavelengths, the wavelength of the light on the longest wavelength side is α, and among the plurality of wavelengths, an arbitrary wavelength on the shorter wavelength side than α is β,
The phase shift amount of the phase shift film in the wavelength alpha and phi _alpha, the phase shift amount of the phase shift film in the wavelength beta when the phi _beta,
φ _β > φ _α
Meet, and the phi _alpha, rather than phi _beta in the arbitrary beta, so that the difference between 180 degrees smaller, and selects the physical properties and thickness of the phase shift film, photo How to design a mask. A method for manufacturing a display device, comprising a step of transferring a transfer pattern of a photomask onto an object to be transferred using an exposure device, wherein the transfer step includes an exposure including intensity peaks at a plurality of wavelengths. In the method for manufacturing a display device, including irradiating the transfer pattern with light,
The photomask includes a transfer pattern in which a phase shift film is patterned on a transparent substrate,
The transfer pattern includes a phase shift portion in which a phase shift film is formed on the transparent substrate, and a translucent portion where the transparent substrate is exposed,
When the transmittance of the phase shift film with respect to g-line is T _g (%),
3 <T _g <15
And
Of the plurality of wavelengths, the wavelength of the light on the longest wavelength side is α, and among the plurality of wavelengths, an arbitrary wavelength on the shorter wavelength side than α is β,
The phase shift amount of the phase shift film in the wavelength alpha and phi _alpha, the phase shift amount of the phase shift film in the wavelength beta when the phi _beta,
φ _β > φ _α
The filled, and the phi _alpha, rather than phi _beta in the arbitrary beta, using the phase shift film having physical properties and thickness as the difference decreases between 180 degrees, the transfer pattern is formed A method for manufacturing a display device.

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