CN106324977B - Photomask, photomask designing method, photomask blank and display device manufacturing method - Google Patents
Photomask, photomask designing method, photomask blank and display device manufacturing method Download PDFInfo
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- CN106324977B CN106324977B CN201610423251.XA CN201610423251A CN106324977B CN 106324977 B CN106324977 B CN 106324977B CN 201610423251 A CN201610423251 A CN 201610423251A CN 106324977 B CN106324977 B CN 106324977B
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/70691—Handling of masks or workpieces
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
- G03F1/26—Phase shift masks [PSM]; PSM blanks; Preparation thereof
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
- G03F1/66—Containers specially adapted for masks, mask blanks or pellicles; Preparation thereof
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/708—Construction of apparatus, e.g. environment aspects, hygiene aspects or materials
- G03F7/7095—Materials, e.g. materials for housing, stage or other support having particular properties, e.g. weight, strength, conductivity, thermal expansion coefficient
- G03F7/70958—Optical materials or coatings, e.g. with particular transmittance, reflectance or anti-reflection properties
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/027—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34
- H01L21/033—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34 comprising inorganic layers
- H01L21/0334—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34 comprising inorganic layers characterised by their size, orientation, disposition, behaviour, shape, in horizontal or vertical plane
- H01L21/0337—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34 comprising inorganic layers characterised by their size, orientation, disposition, behaviour, shape, in horizontal or vertical plane characterised by the process involved to create the mask, e.g. lift-off masks, sidewalls, or to modify the mask, e.g. pre-treatment, post-treatment
Abstract
The present invention provides a photomask, a method for manufacturing the photomask, a method for designing the photomask, a photomask blank and a method for manufacturing a display device, wherein a resist pattern with a favorable shape can be formed during transfer of the pattern and excellent transfer property is displayed. The photomask has a transfer pattern including a patterned phase shift film on a transparent substrate. The transfer pattern includes a phase shift portion having a phase shift film formed on the transparent substrate, and a light transmitting portion where the transparent substrate is exposed. The phase shift amount (degree) of g line of the phase shift film is
The phase shift amount (degree) for the h line is
The phase shift amount (degree) for the i-line is
When it is, then satisfy
And these
In which the closest value to 180 degrees is
Description
Technical Field
The present invention relates to a photomask having a pattern for transfer on a transparent substrate. And more particularly, to a photomask advantageous for manufacturing a display device, a method of manufacturing the photomask, a method of designing the photomask, a photomask blank for manufacturing the photomask, and a method of manufacturing a display device using the photomask.
Background
Patent document 1 proposes to use a photomask in which a phase inversion film and a light shielding film are sequentially etched when the photomask is used to manufacture an FPD (flat panel display) device.
Here, a photomask having a phase inversion film is described, which involves the following problems: in a photomask used for manufacturing an FPD device, if a lens is enlarged by shortening the wavelength of a light source in order to improve the resolution of a pattern, the focal depth of the lens is reduced, and there is a limit to obtaining a practical resolution of a pattern. Further, the phase inversion film is desirably set to have a phase difference deviation of 10 ° or less for the i-line, h-line, and g-line.
Prior art literature
Patent literature
Patent document 1: japanese patent application laid-open No. 2012-230379
Disclosure of Invention
Problems to be solved by the invention
In display devices including liquid crystal display devices and EL display devices, it is desired to achieve improvement in display performance such as high definition, high speed display, and wide viewing angle while saving power and being brighter.
For example, in the thin film transistor (Thin Film Transistor, TFT) used in the display device, among two or more patterns constituting the TFT substrate, the contact Kong Re formed in the interlayer insulating film does not have a function of reliably connecting the upper layer and the lower layer, and thus, it is not possible to ensure an accurate operation. On the other hand, in order to increase the aperture ratio of the display device as much as possible and to make a bright, power-saving display device, it is required that the aperture diameter of the contact hole is sufficiently small. Along with this, the aperture of the hole pattern provided in the photomask for forming such contact holes is also required to be miniaturized (for example, smaller than 4 μm). For example, a pore pattern having a pore diameter of 2.5 μm or less and a pore diameter of 2.0 μm or less is required, and it is considered that in the near future, it is also desired to form a pattern having a pore diameter of 1.5 μm or less smaller. In view of such a background, a display device manufacturing technique capable of reliably transferring a minute contact hole is demanded.
In the field of photolithography for manufacturing a display device, an exposure device known as an LCD (or an FPD) has an NA (numerical aperture) of about 0.08 to 0.10, and a wide wavelength range including i-line, h-line, and g-line is often used as an exposure light source, so that high production efficiency and favorable cost are realized.
However, in the field of photolithography for manufacturing the display device as described above, the miniaturization of the pattern is also required more than before. The present inventors have attempted to solve the following problems: the manufacturing of a finer display device is stably performed without deteriorating productivity and cost.
In patent document 1, when a phase inversion film is used for a photomask pattern, resolution is improved by canceling interference of exposure light at the boundary of the phase inversion film. It is desirable to form the phase inversion film so that the phase difference for the i-line, h-line, g-line is close to 180 °, but it is inevitable that the phase difference is different depending on the wavelength, and therefore it is desirable to reduce the phase difference deviation for the exposure light as much as possible. In this case, the phase difference of the phase inversion film is preferably 180 ° for exposure light of any wavelength.
However, in order to minimize the phase difference deviation, it is necessary to develop a film material having such physical properties, and the search for such a material is not easy.
Accordingly, an object of the present invention is to provide a photomask which can form a resist pattern having an advantageous shape and which exhibits excellent transferability at the time of pattern transfer, and to achieve this object, the present inventors have found a photomask which can perform transfer with excellent resolution even when a film material having a phase difference deviation is used, and have made intensive studies with the object of achieving the present invention.
Means for solving the problems
The present invention provides a photomask comprising a transparent substrate and a transfer pattern comprising a patterned phase shift film, characterized in that,
the transfer pattern includes a phase shift portion for forming a phase shift film on the transparent substrate, and a light transmitting portion for exposing the transparent substrate,
the phase shift amount (degree) of g line of the phase shift film is
The phase shift film has a phase shift amount (degree) with respect to the h line of
The phase shift film has a phase shift amount (degree) with respect to the i line of
In the time-course of which the first and second contact surfaces,
satisfy the following requirements
And, these
In which the value closest to 180 degrees is +.>
In the photomask of the present invention, the configuration 2 is a configuration 1, and the transmittance to g-line is 3< Tg <15, provided that the phase shift film has a transmittance Tg (%).
In the configuration 3 of the present invention, the photomask of the configuration 1 or 2 is characterized in that when the transmittance to g line is Tg (%) and the transmittance to i line is Ti (%), the phase shift film has Ti < Tg.
The present invention provides a photomask according to claim 4, wherein the transfer pattern includes an isolated hole pattern having a hole diameter of 4 μm or less.
The configuration 5 of the present invention is a photomask according to any one of claims 1 to 4, wherein the photomask is a photomask in which light having a wavelength range of i line to g line is used as exposure light.
The photomask according to claim 6 of the present invention is the photomask according to any one of claims 1 to 5, wherein the transparent substrate further comprises a patterned light shielding film.
The invention provides a photomask according to any one of claims 1 to 6, wherein the photomask is provided with a transfer pattern for manufacturing a display device.
The present invention provides a photomask blank having a phase shift film formed on a transparent substrate, wherein the photomask blank is used for patterning the phase shift film to form a transfer pattern to form a photomask,
the phase shift amount (degree) of g line of the phase shift film is
The phase shift film has a phase shift amount (degree) with respect to the h line of
The phase shift film has a phase shift amount (degree) with respect to the i line of
When (I)>
Then satisfy
And, these
In which the value closest to 180 degrees is +.>
In the photomask blank according to the present invention, the configuration 9 is the photomask blank according to the configuration 8, wherein when the transmittance to g line of the phase shift film is Tg (%), the transmittance is 3< Tg <15.
The photomask blank according to the present invention, which is the configuration 10 of the present invention, is characterized in that when the transmittance for g line is Tg (%) and the transmittance for i line is Ti (%) of the phase shift film, ti < Tg.
The configuration 11 of the present invention is a photomask blank according to any one of claims 8 to 10, wherein the photomask blank is used for manufacturing a photomask using light having a wavelength range of i line to g line as exposure light.
In the configuration 12 of the present invention, the photomask blank according to any one of claims 8 to 11 is further formed with a light shielding film on the phase shift film.
The present invention provides a photomask manufacturing method, comprising:
a step of preparing a photomask blank according to any one of claims 8 to 12; and
and patterning the phase shift film included in the photomask blank to form a pattern for transfer.
The present invention provides a photomask design method including a transfer pattern including a patterned phase shift film on a transparent substrate, characterized in that,
the photomask is used for transferring the pattern for transfer to a transfer object by using exposure light having intensity peaks in at least two wavelengths,
the transfer pattern includes a phase shift portion having a phase shift film formed on the transparent substrate, and a light transmitting portion where the transparent substrate is exposed,
when the transmittance to g line of the phase shift film is Tg (%),
then 3< tg <15,
further, the wavelength of the light on the longest wavelength side of the two or more wavelengths is alpha, and any wavelength on the shorter wavelength side than alpha of the two or more wavelengths is beta,
the phase shift amount of the phase shift film in the wavelength alpha is set as
The phase shift amount of the phase shift film in the wavelength beta is
When it is, then satisfy->
The physical properties and film thickness of the phase shift film are selected so that the phase shift film
The difference from 180 degrees is smaller than +.>
And 180.
The present invention provides a method for manufacturing a display device, comprising a step of transferring a transfer pattern of a photomask onto a transfer object using an exposure device, wherein the transfer step of the method for manufacturing a display device includes irradiating the transfer pattern with exposure light having intensity peaks at two or more wavelengths,
the photomask includes a transfer pattern formed by patterning a phase shift film on a transparent substrate,
the transfer pattern includes a phase shift portion on which a phase shift film is formed on the transparent substrate, and a light transmitting portion on which the transparent substrate is exposed,
when the transmittance to g line of the phase shift film is Tg (%),
then 3< tg <15,
further, the wavelength of the light on the longest wavelength side of the two or more wavelengths is alpha, and any wavelength on the shorter wavelength side than alpha of the two or more wavelengths is beta,
the phase shift amount of the phase shift film in the wavelength alpha is set as
The phase shift amount of the phase shift film in the wavelength beta is
When it is, then satisfy->
And, use is made of the composition having the above
The difference from 180 degrees is smaller than +.>
The transfer pattern is formed by a phase shift film having physical properties and film thickness different from 180 degrees.
Effects of the invention
According to the present invention, a photomask which can form a resist pattern of an advantageous shape at the time of transfer of the pattern and which exhibits excellent transferability can be obtained.
Drawings
Fig. 1 is a diagram showing a cross section of a resist film transferred with a hole pattern and a photomask for transfer of the hole pattern.
Fig. 2 is a graph of light intensity when exposing the hole pattern of the photomask shown in fig. 1.
Fig. 3 is a graph showing changes in ILS and contrast with the thickness of the phase shift film and the amount of phase shift at that thickness.
Fig. 4 is a graph showing changes in ILS and contrast with the thickness of the phase shift film and transmittance at that thickness.
Detailed Description
The photomask of the present invention is a photomask comprising a transfer pattern including a patterned phase shift film on a transparent substrate. The transfer pattern includes a phase shift portion having a phase shift film formed on the transparent substrate, and a light transmitting portion where the transparent substrate is exposed.
Further, the method comprises the steps of,
the phase shift amount (degree) of g line of the phase shift film is
The phase shift film has a phase shift amount (degree) with respect to the h line of
The phase shift film has a phase shift amount (degree) with respect to the i line of
In the time-course of which the first and second contact surfaces,
then satisfy
And, these
In which the value closest to 180 degrees is +.>
In this 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 substrate obtained by polishing a transparent material such as glass flat and smooth can be used. As a photomask for manufacturing a display device, a rectangle having one side of a main surface of 300mm or more is preferable.
A transfer pattern provided in a photomask of the present invention includes a phase shift portion having a phase shift film formed on a transparent substrate and a light transmitting portion exposed on the surface of the transparent substrate.
Such a photomask (also referred to as a phase shift mask) inverts the phase of the light transmitted through the phase shift portion (180-degree shift), and reduces the light intensity near the boundary between the phase shift portion and the light transmission portion by the interference of the light having the inverted phase. Further, it is desired to improve resolution by affecting the light intensity distribution received by the transfer object. When the transmittance T (%) of the exposure light provided in the phase shift portion is too low, the effect of improving the resolution by the phase shift portion tends to be reduced. When the transmittance T (%) of the exposure light of the phase shift portion is too high, the loss of the resist thickness described later tends to become remarkable. In view of these, 3< t <15 is preferred. For example, when a phase shift film having a transmittance of Tg (%) for g-line is used, 3< Tg <15 may be set.
On the other hand, exposure light (also referred to as wide-wavelength light) having two or more wavelengths is used in an exposure apparatus for manufacturing a display device. For example, exposure light having peaks at i-line (365 nm wavelength), h-line (405 nm wavelength), and g-line (436 nm wavelength) and using an ultra-high pressure mercury lamp as a light source is used, whereby a photomask having a large area can be effectively exposed.
However, the exposure light includes two or more componentsIn the case of the wavelengths of (a) the phase is correctly inverted (i.e., 180 degrees phase shifted) for any of these wavelengths, which is difficult for a phase shift mask having a single phase shift film. Therefore, it is advantageous that even if it is considered that in the phase shift film, the phase shift amount varies depending on the wavelength of light (specifically, even if it is as described above
) A photomask having excellent transferability can also be obtained.
In the present invention, when the transmittance to g line is Tg (%) and the transmittance to i line is Ti (%) of the phase shift film, ti < Tg is preferable.
There are excellent phase shift film materials satisfying such conditions.
More preferably, if the transmittance to the h line of the phase shift film is Th (%), ti < Th < Tg.
The present inventors have studied a method for transferring a fine pattern with sufficient CD (Cristal Dimension) accuracy and stability using such a material.
In the photomask of the present invention, the mask,
the phase shift amount (degree) of g line of the phase shift film is
The phase shift film has a phase shift amount (degree) with respect to the h line of
The phase shift film has a phase shift amount (degree) with respect to the i line of
In the time-course of which the first and second contact surfaces,
these are
In which the value closest to 180 degrees is +.>
As described above, the "value closest to 180 degrees" includes a case equal to 180 degrees.
That is, the photomask of the present invention has the following phase shift film: the phase shift film has a phase shift effect of 180 degrees or nearly 180 degrees for g-lines on the longest wavelength side among i-lines, h-lines, and g-lines, as compared with i-lines and h-lines. In other words, it was found to be advantageous to design the photomask as follows: in the design of this photomask, a photomask using a wide wavelength light for exposure is designed to have a phase shift amount of 180 degrees or closest to 180 degrees with respect to a wavelength on the long wavelength side (here, g-line on the longest wavelength side among peaks of the exposure light).
Hereinafter, a case where exposure light having a peak in the wavelengths of the i-line, h-line, and g-line is used as the wide wavelength light will be described as an example.
The i-line is the shortest of these 3 wavelengths. In view of the fine-size portion of the transfer pattern, a higher resolution can be expected if the wavelength is sufficiently short, and thus, a film design of a photomask based on the i-line of the above 3 wavelengths is considered. Namely, a method of manufacturing a phase shift mask using a phase shift film showing a phase shift closest to 180 degrees for the i-line wavelength (365 nm). In this case, since the phase shift amount is greatly deviated from 180 degrees (for example, 150 degrees to 160 degrees) for the g line farthest from the i line, it is expected that the phase shift effect for the g line is reduced. To avoid this, the following design is also considered: of these 3 wavelengths, the phase shift amount is closest to 180 degrees for the h-line located almost in the center. However, no study has been made on what effect the mask design including the above-described idea actually has on transferability.
In a process for manufacturing a display device, a transfer pattern provided in a photomask is transferred onto a resist film (for example, a positive photoresist film) coated on a transfer object (for example, a display substrate), and developed to obtain a resist pattern. Then, the thin film of the transfer target is etched. At this time, it is known that the etching accuracy is significantly affected by the shape of the resist pattern.
For example, when a small hole pattern is to be transferred onto a resist film formed on the transfer target, resolution becomes difficult as the aperture decreases. Then, when a phase shift mask is used for transfer, resist damage occurs in the formed resist pattern due to thickness loss of the resist film around the hole as the irradiation light amount increases. As a reference example, simulation results showing this situation are shown in fig. 1 (a) and (b). Here, (a) of fig. 1 shows a resist pattern cross section formed in the resist film 30 when the phase shift mask shown in (c) of fig. 1 is exposed by the FPD exposure device. Fig. 1 (b) shows a resist pattern cross section formed in the resist film 30 when the phase shift mask shown in fig. 1 (d) is exposed by the FPD exposure device.
In the phase shift mask shown in fig. 1 (c) and (d), a square isolated hole pattern 20 is formed in the phase shift film 10 having a transmittance Ti of 5% for the i-line. The aperture of the isolated hole pattern in the photomask shown in fig. 1 (c) (here, the length of one side of the isolated hole pattern 20) was 3.0 μm, and the aperture of the isolated hole pattern in the photomask shown in fig. 1 (d) was 2.5 μm.
In order to perform an excellent function as an etching mask, it is advantageous that the inclination of the edge is vertical (the angle θ shown in fig. 1 (b) is as close to vertical as possible) in terms of the shape of the resist pattern, and at this time, stable etching accuracy can be obtained, and finally excellent dimensional accuracy can be obtained. However, as shown in fig. 1 (a) and (b), when the pattern aperture is found to be small, θ becomes small, and the inclination (toppling) of the resist pattern end tends to become remarkable.
In addition, in the resist film residue portion, it is advantageous that a resist of a sufficient thickness remains, and the thickness of fig. 1 (b) having a smaller pore diameter is smaller than that of fig. 1 (a). Since the phase shift film has a predetermined light transmittance, the light intensity is reduced by interference of light in the vicinity of the edge, but a so-called side lobe is generated at a position slightly distant from the edge. Eventually, a defect that damages the thickness of the resist residue film occurs. In particular, in the transmitted light intensity distribution, near the position where the side lobe is generated, the resist generates a concave portion, and the amount of residual film is a minimum value (point B in fig. 1 (B)).
Therefore, it is desirable that the minimum portion of the residual film thickness of the resist, that is, the difference in height between the end portion of the resist pattern (point a of fig. 1 (B), hereinafter also referred to as the edge position) and the position of the above-mentioned resist recess (point B of fig. 1 (B), hereinafter also referred to as the side lobe position) (H of fig. 1 (B)) is large.
From the above, it is significant to evaluate the shape of the resist pattern based on the inclination θ of the end portion of the resist pattern and the thickness H of the minimum portion of the resist film residue. In terms of an optical Image formed by light transmitted through a photomask, the index for evaluating the optical Image may be ILS (Image Log-Slope) or contrast (Michelson Contrast), and it is considered to be advantageous to adopt a condition that these values can be sufficiently improved. This can be expressed by the following parameters with reference to the transmitted light intensity curve shown in fig. 2. Fig. 2 is a graph of light intensity as an optical image formed when exposing a pattern such as the patterns (c) and (d) in fig. 1, where a 'corresponds to an edge position and B' corresponds to a side lobe position.
[ number 1 ]
[ number 2 ]
Here the number of the elements is the number,
i (Xedge) is the light intensity at the position Xedge corresponding to the pattern edge position in the light intensity distribution.
I (xsilobe) is the light intensity at the position xsilobe corresponding to the side lobe position in the light intensity distribution.
Fig. 3 shows a simulation result showing how ILS (left vertical axis) and contrast (right vertical axis) change with a change in thickness of a phase shift film (upper horizontal axis) and a phase shift amount (lower horizontal axis) linked thereto when transferred to a positive photoresist coated on a transfer object using a phase shift mask having an isolated hole pattern with an aperture of 3 μm under the same exposure conditions as in fig. 1.
The conditions applied in this simulation are as follows: the NA (numerical aperture) of the optical system of the exposure apparatus was 0.083, σ (coherence coefficient) was 0.7, and the phase shift film contained MoSi. In the wavelength region of the exposure light, the transmittance of the phase shift film has a positive correlation with respect to the wavelength.
On the lower horizontal axis, the film thicknesses of the phase shift films used for the i-line (365 nm), the h-line (405 nm), and the g-line (436 nm) which were shifted by 180 degrees are denoted as L, M, N, respectively. That is, if the phase shift film is used in the form of a film thickness L, the phase shift film is an i-line reference phase shift film; if the phase shift film is used in the form of a film thickness M, the phase shift film is a phase shift film of an h line reference; when the phase shift film is used as the film thickness N, the phase shift film is a g-line reference.
As can be understood from fig. 3, the ILS shows a maximum value in the h-line reference, and gradually decreases in the i-line and g-line references. On the other hand, the contrast increases monotonically in this wavelength region, and therefore the highest value is shown on the maximum wavelength side. That is, the wavelength decreases sharply when it becomes short.
Considering only ILS, that is, the edge slope shape of the formed resist pattern, it is considered that it is preferable to apply a film (hereinafter referred to as an h-line reference phase shift film) that is 180 degrees phase-shifted with respect to the h-line. However, when the influence of the contrast, that is, the resist loss around the target pattern is considered at the same time, it is clearly advantageous to select a film thickness (g-line reference phase shift film) having a g-line phase shift of 180 degrees. This is because the g-line reference phase shift film is slightly inferior in ILS to the h-line reference phase shift film, but can enjoy advantages over this in contrast. In fact, in the mask using the g-line reference phase shift film illustrated in fig. 3, excellent transferability was exhibited in which ILS had a value of 1.50 or more and a contrast ratio of 0.6 or more.
Since the transmittance of the phase shift mask was studied, the graph showing the transmittance of the phase shift film on the horizontal axis is shown in fig. 4.
From this, it can be understood that the balance of ILS and contrast is appropriate in the region where the transmittance Tg for the g line is 3% to 15%. More preferably, the transmittance Tg is 3 to 10%.
In the present invention, a phase shift film having a positive correlation in transmittance with respect to wavelength may be applied, but the following may be also applied: the following expression holds between the transmittance Tg (%) for g-line and the transmittance Ti (%) for i-line.
3≤Tg-Ti≤10
More preferably, 4.ltoreq.Tg-Ti.ltoreq.9.
Wherein, even if the value of Tg-Ti is less than 4, the effect of the present invention can be obtained.
Further, as the phase shift characteristics that can be applied to the phase shift film of the present invention, the following are suitable examples: in the phase shift amount for g-line
And the amount of phase shift for the i line +.>
The following equation holds.
More specifically, the process is carried out,
in the phase-shifting film of the present invention,
ratio->
More nearly 180 degrees. />
When the difference is 180 degrees or not 180 degrees, the difference may be within a predetermined range. Preferably, the->
The difference from 180 degrees is preferably 30 degrees or less, more preferably 20 degrees or less, and still more preferably 10 degrees or less.
As the phase shift amount for each wavelength, the following is preferable:
Further, the following is exemplified: let the phase shift amount for the h line be
In this case, the following equation is established.
It is further preferred that the composition comprises,
as can be 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 may be, for example, a film containing Si, cr, ta, zr or the like, and an appropriate substance may be selected from oxides, nitrides, carbides, and the like thereof. As the Si-containing film, a Si compound (SiON or the like), or a transition metal silicide (MoSi or the like), or a compound thereof can be used. As the compound of MoSi, oxide, nitride, oxynitride, or the like of MoSi can be exemplified.
When the phase shift film is a film containing Cr, a Cr compound (oxide, nitride, carbide, oxynitride, carbonitride, oxynitride) can be used.
Of course, the photomask of the present invention may have a film or film pattern other than the phase shift film as long as the effect of the present invention is not impaired. Examples thereof include a light shielding film, an etching stopper film, an antireflection film, and a charge control film. In this case, the film in contact with the phase shift film of the present invention is preferably a material having mutual etching selectivity with the phase shift film. As a candidate material, a material selected from those listed for the phase shift film may be selected.
The use of the photomask of the present invention is not particularly limited. However, the transfer pattern is advantageous in a pattern having a fine size, particularly in an isolated pattern.
For example, the pattern for transfer may include an isolated hole pattern having a pore diameter of 4 μm or less. The invention is remarkable in the case of an isolated hole pattern of preferably less than 3.5 μm, more preferably less than 3 μm, and still more preferably less than 2.5 μm. As can be understood from fig. 1, there is a pattern having an aperture of 2 μm or less for future movement of a display device, and the present invention can be applied to such a pattern.
Here, if the shape of the pattern is circular, the aperture of the pattern refers to the diameter; if square, the aperture of the pattern refers to the length of one side; if the pattern is other regular polygons, the aperture of the pattern refers to the diameter of the circumscribed circle; if rectangular, the aperture of the pattern refers to the length of the short side.
Here, the isolated (iso) pattern refers to the following pattern. That is, when two or more patterns are regularly arranged and optically act on each other due to the interference of transmitted light to form a transferred image, and the patterns are dense patterns, the other patterns are referred to as isolated patterns.
More preferably, when the aperture of 1 isolated pattern is D μm, no other pattern exists in a distance range of at least 2D from the outer edge of the pattern. The following may be exemplified: for example, when the D μm light transmitting portion is an isolated pattern having a shape surrounded by the phase shift portion, only the phase shift portion is present in a distance range of at least 2D from the outer edge of the light transmitting portion. Preferably, no other pattern is present in the 3D range.
The hole pattern may be a "slit" (opening) pattern formed in the phase shift film.
In the intended display device, the hole pattern as described above may be a pattern for forming a contact hole, but is not limited to this use.
The transfer pattern provided in the photomask of the present invention is transferred onto a resist film on a transfer object, and a resist pattern of a good shape can be formed, and the resist film may be a photoresist film. There is no limitation on the positive type or the negative type, but 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 regions of i line, h line, and g line, and the sensitivity is reduced for light on the high wavelength side or the low wavelength side compared to the above wavelength regions.
In the above, the superiority of the phase shift film on the g-line basis is explained. In designing the mask, it is advantageous that the phase shift amount for the wavelength on the long wavelength side of the two or more wavelengths included in the exposure light is closer to 180 degrees than the phase shift amount for the wavelengths other than the two, and in this case, the effects of the present invention can be obtained. The present invention includes a method of designing such a photomask.
The photomask of the present invention may further have a light shielding film pattern obtained by patterning the light shielding film. In this case, the light shielding film pattern may be a part of the pattern for transfer, or may be outside the region of the pattern for transfer. In the former case, the transfer pattern may include a light shielding portion formed of a phase shift film and a light shielding film, in addition to the light transmitting portion and the phase shift portion. In the latter case, the marking pattern for product recognition, and the calibration pattern used at the time of photomask manufacture or use may be used.
As described above, the use of the photomask of the present invention is not limited, and excellent effects can be obtained in a display device (including a display device known as LCD (Liquid Crystal Display) or OLED (Organic Light-Emitting Diode)).
The present invention includes photomask blanks useful in obtaining the above-described photomasks. In the photomask blank for forming a transfer pattern by patterning the phase shift film,
the phase shift amount (degree) of g line of the phase shift film is
The phase shift film has a phase shift amount (degree) with respect to the h line of
The phase shift film has a phase shift amount (degree) with respect to the i line of
In the time-course of which the first and second contact surfaces,
then satisfy
And, these
In which the value closest to 180 degrees is +.>
The "value closest to 180 degrees" includes a case where the value is equal to 180 degrees.
When the transmittance to g line is Tg (%) and the transmittance to i line is Ti (%) of the phase shift film,
then Ti < Tg is preferred.
The characteristics concerning the phase shift film are as described above.
The present invention also includes a method for manufacturing a photomask, in which the photomask blank is prepared, and a phase shift film included in the photomask blank is patterned to form a pattern for transfer.
In addition, the invention includes a method of designing a photomask. Namely, a photomask design method,
a method for designing a photomask comprising a transfer pattern including a patterned phase shift film on a transparent substrate, characterized by,
the photomask is used for transferring the pattern for transfer to a transfer object by using exposure light having intensity peaks in at least two wavelengths,
the transfer pattern includes a phase shift portion having a phase shift film formed on the transparent substrate, and a light transmitting portion where the transparent substrate is exposed,
when the transmittance of the phase shift film to the g line is Tg (%),
then 3< tg <15,
and, let the wavelength of the light at the longest wavelength side of the above two or more wavelengths be alpha,
the phase shift of the phase shift film at the wavelength alpha is set as
When (I)>
Determining the physical properties and film thickness of the phase shift film so that the phase shift film
The difference from 180 degrees is smaller than the difference from 180 degrees in the phase shift amount in the wavelengths other than α among the above two or more wavelengths.
Here, two or more wavelengths are included in a sensitivity region of a resist used at the time of photomask exposure. In addition, the characteristics of the phase shift film and the like are the same as those described above.
For example, the phase shift film may have a positive correlation between the wavelength and the value of the light transmittance in the two or more wavelength regions.
The photomask designed by the design method of the present invention can be manufactured by applying a known process. That is, a resist film is formed on the surface of a transparent substrate by a film forming method such as sputtering, whereby a photomask blank with a resist is prepared. The resist may be a positive or negative photoresist, and may be, for example, a positive type. The photomask blank is drawn in a desired pattern by using a drawing device. As the drawing device used herein, a laser drawing device 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. The 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 etching is relatively easy for substrates having a large size and a plurality of sizes. After etching, the resist pattern is removed, thereby completing a photomask having a transfer pattern of the phase shift film formed thereon. The desired transfer pattern can be formed by adding a light shielding film or other film forming, drawing, and patterning step to the above steps according to the use of the photomask by a known method.
Further, the present invention includes a method for manufacturing a display device using the photomask.
That is, a method for manufacturing a display device including a step of transferring a pattern for transfer provided in a photomask to a transfer object by using an exposure device, wherein the step of transferring includes irradiating the pattern for transfer with exposure light having intensity peaks at two or more wavelengths,
it is characterized in that the method comprises the steps of,
the photomask includes a transfer pattern formed by patterning a phase shift film on a transparent substrate,
the transfer pattern includes a phase shift portion having a phase shift film formed on the transparent substrate, and a light transmitting portion where the transparent substrate is exposed,
when the transmittance to g line of the phase shift film is Tg (%),
then 3< tg <15,
and, let the wavelength of the longest wavelength side light of the above two or more wavelengths be alpha,
the phase shift amount of the phase shift film in the wavelength alpha is set as
In the time-course of which the first and second contact surfaces,
using the above
The transfer pattern is formed by a phase shift film having physical properties and film thickness such that a difference from 180 degrees is smaller than a difference between a phase shift amount in a wavelength other than α of the two or more wavelengths and 180 degrees.
Here, two or more wavelengths are also included in the sensitivity region of the resist used in the photomask exposure. As the exposure apparatus used here, an equivalent exposure apparatus having an optical system with a Numerical Aperture (NA) of 0.08 to 0.15 and a coherence coefficient (σ) of about 0.5 to 1.0 is suitably used.
For transferability of a photomask to be exposed using light in a wide wavelength range 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, which exceeds the predicted operational effect.
In the photomask for exposure using only i-line and h-line, the amount of phase shift is preferably selected
And->
In (a) and (b)
More nearly 180 degrees.
Symbol description
10. Phase shift film
20. Isolated hole pattern
30. Resist film
Claims (5)
1. A photomask having a pattern for transfer for manufacturing a display device including a patterned phase shift film on a transparent substrate, the photomask being used for forming a hole pattern on a transferred body by using an exposure light source including i-lines, h-lines and g-lines,
the transfer pattern includes an isolated hole pattern having an aperture of 4 [ mu ] m or less, the isolated hole pattern being composed of a phase shift portion having a phase shift film formed on the transparent substrate and a light transmitting portion exposed from the transparent substrate,
the phase shift amount (degree) of g line of the phase shift film is set as
The phase shift film has a phase shift amount (degree) for h-line of
The phase shift film has a phase shift amount (degree) for the i-line of
In the time-course of which the first and second contact surfaces,
then satisfy
And, these
In which the value closest to 180 degrees is +.>
2. The photomask according to claim 1, wherein when the transmittance of the phase shift film to the g line is tg%, the transmittance is 3< Tg <15.
3. The photomask according to claim 1 or 2, wherein when the transmittance of the phase shift film to g line is Tg and the transmittance to i line is ti%, ti < Tg.
4. The photomask according to claim 1 or 2, wherein the pattern for transfer is an isolated hole pattern having a hole diameter of less than 2.5 μm.
5. The photomask according to claim 1 or 2, wherein the transparent substrate is further provided with a patterned light shielding film.
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| CN201910485133.5A CN110262182B (en) | 2015-06-30 | 2016-06-15 | Photomask, photomask designing method, photomask blank and display device manufacturing method |
| CN202110223505.4A CN112987484A (en) | 2015-06-30 | 2016-06-15 | Photomask, photomask designing method, photomask blank, and method for manufacturing display device |
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| JP2015130976A JP6767735B2 (en) | 2015-06-30 | 2015-06-30 | Photomasks, photomask design methods, photomask blanks, and display device manufacturing methods |
| JP2015-130976 | 2015-06-30 |
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| CN201910485133.5A Division CN110262182B (en) | 2015-06-30 | 2016-06-15 | Photomask, photomask designing method, photomask blank and display device manufacturing method |
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Also Published As
| Publication number | Publication date |
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| TWI613508B (en) | 2018-02-01 |
| TW201704846A (en) | 2017-02-01 |
| CN110262182A (en) | 2019-09-20 |
| CN106324977A (en) | 2017-01-11 |
| CN110262182B (en) | 2023-05-26 |
| JP2017015863A (en) | 2017-01-19 |
| JP6767735B2 (en) | 2020-10-14 |
| KR20170003412A (en) | 2017-01-09 |
| KR101898327B1 (en) | 2018-09-12 |
| CN112987484A (en) | 2021-06-18 |
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