Method for manufacturing a phase shift mask and display device.

Abstract

To provide a phase shift mask that is advantageously adapted to an exposure environment of a mask for manufacturing a display device, and has excellent transfer resolution of a fine hole pattern.SOLUTION: A phase shift mask 10 comprises a translucent part 11, a phase shift part 12, and a light-shielding part 13 on a translucent substrate 1, where the translucent substrate 1 is exposed in a hole shape in the translucent part 11, the phase shift part 12 is provided so as to surround an outer periphery of the translucent part 11, the light-shielding part 13 is provided so as to surround an outer periphery of the phase shift part 12, the outer periphery of the translucent part 11 is in a square shape having a curve of curvature radius RT at least on one corner part, the outer periphery of the phase shift part 12 is in a square shape at least having a curve of curvature radius RP at a corner part adjacent to the corner part having the curve of curvature radius RT, and the curvature radius RT and the curvature radius RP satisfy a relationship of RT≥RP.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a phase shift mask and a display device. [Background technology]

[0002] In recent years, display devices such as FPDs (Flat Panel Displays), exemplified by OLEDs (Organic Light Emitting Diodes), have seen rapid advancements in screen size, viewing angle, flexibility (such as folding), resolution, and display speed. One of the elements necessary for this resolution and display speed is the fabrication of fine, dimensionally accurate electronic circuit patterns, including elements and wiring. Photolithography is often used for patterning these electronic circuits for display devices. Therefore, a phase-shift mask for manufacturing display devices with fine, high-precision patterns is required. This phase-shift mask is formed by creating a halftone film with low transmittance and a 180-degree phase shift in the portion corresponding to the light-shielding area of ​​a binary mask.

[0003] For example, Patent Document 1 describes a halftone type phase shift mask comprising: a transparent portion 1 made of a substrate transparent to exposure light; a semi-transparent portion 2 formed on the substrate surrounding the transparent portion 1 by a semi-transparent phase shifter layer having a film thickness d represented by d = kλ / (n-1) (where n is the refractive index of the phase shifter with respect to the exposure wavelength λ, and k is an odd integer) with respect to the wavelength λ of the exposure light and having a transmittance to exposure light of 5 to 20%; and an outer region portion 3 made of a light-shielding layer or a light-diffusing layer laminated on the semi-transparent phase shifter layer outside the region of the semi-transparent portion 2. Furthermore, Patent Document 2 describes a method for manufacturing a photomask, comprising the steps of: preparing a photomask blank formed by laminating a lower layer film and an upper layer film on a transparent substrate; a pre-etching step for the upper layer film, in which the upper layer film is etched using a resist pattern formed on the upper layer film as a mask; a lower layer film patterning step, in which the lower layer film is etched using at least the etched upper layer film as a mask to form a lower layer film pattern; and an upper layer film patterning step, in which the upper layer film is side-etched using at least the resist pattern as a mask to form an upper layer film pattern. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 9-325468 [Patent Document 2] Patent No. 5993386 [Overview of the project] [Problems that the invention aims to solve]

[0005] For example, in the case of thin-film transistors (TFTs) used in the above-mentioned display devices, correct operation cannot be guaranteed unless the contact holes formed in the interlayer insulating film, among the multiple patterns that make up the TFT, reliably connect the patterns of the upper and lower layers. On the other hand, in order to make a display device that is bright and energy-efficient by maximizing the aperture ratio of the display device, the diameter of the contact holes must be sufficiently small. Accordingly, the diameter of the hole patterns in the photomasks used to form such contact holes is also desired to be miniaturized (for example, less than 3 μm). For example, hole patterns with a diameter of 2.5 μm or less, and even 2.0 μm or less, are required, and in the near future, it is thought that the formation of patterns with a diameter of 1.5 μm or less will also be desired. Against this backdrop, there is a need for manufacturing technology for display devices that can reliably transfer minute contact holes.

[0006] However, conventionally, it has been found that obtaining a phase-shift mask and a method for manufacturing a display device that are advantageously suited to the exposure environment of a mask for manufacturing a display device and have excellent transfer resolution for fine hole patterns has not been easy.

[0007] The present invention was made to solve the above-mentioned problems. Specifically, the present invention aims to provide a phase-shift mask and a method for manufacturing a display device that are advantageously suited to the exposure environment of a mask for manufacturing a display device and have excellent transfer resolution for fine hole patterns. [Means for solving the problem]

[0008] The present invention has the following configuration as a means of solving the above problems.

[0009] (Configuration 1) A phase shift mask comprising a light-transmitting portion, a phase shift portion, and a light-shielding portion on a light-transmitting substrate, The light-transmitting portion is formed by exposing a light-transmitting substrate in the shape of a hole. The phase shift portion is provided so as to surround the outer periphery of the light-transmitting portion, The light-shielding portion is provided so as to surround the outer circumference of the phase-shift portion. The outer circumference of the light-transmitting portion has a radius of curvature R at at least one corner. T It is a quadrilateral shape with curves, The outer circumference of the phase shift portion has the radius of curvature R T The corner having a curve and the adjacent corner have a radius of curvature R P It is a quadrilateral shape having at least the curve, The radius of curvature R T and the radius of curvature R P R T ≧R P Satisfying the relationship A phase shift mask characterized by the following features.

[0010] (Configuration 2) The width of the phase shift portion is smaller than the size of the light-transmitting portion. A phase shift mask according to configuration 1, characterized by the above.

[0011] (Configuration 3) The phase shift unit has a transmittance of 5% or more to exposure light, The phase difference between the exposure light transmitted through the phase shift portion and the exposure light transmitted through the light-transmitting portion is between 150 degrees and 210 degrees. A phase shift mask according to configuration 1 or 2, characterized by the above.

[0012] (Configuration 4) The phase shift mask according to Configuration 1 or 2, characterized in that the light-shielding portion has an optical density OD of 2 or more with respect to exposure light. (Configuration 5) The phase shift mask according to Configuration 2, characterized in that the width of the phase shift portion is 0.5 μm or more and 2.0 μm or less.

[0013] (Configuration 6) The phase shift mask according to Configuration 2, characterized in that the size of the light-transmitting portion is 4 μm or less.

[0014] (Configuration 7) Radius of curvature R of the light-transmitting portion T The phase shift mask according to configuration 1 or 2, characterized in that the particle size is 0.4 μm or larger.

[0015] (Configuration 8) The phase shift mask according to Configuration 1 or 2, characterized in that the phase shift portion consists of a phase shift film, and the light-transmitting portion consists of a configuration in which a part of the phase shift film is removed in the shape of a hole to expose a light-transmitting substrate. (Configuration 9) The phase shift mask according to Configuration 8, characterized in that the light-shielding portion is formed by laminating the phase shift film and the light-shielding film.

[0016] (Configuration 10) A step of placing the phase shift mask described in Configuration 1 or 2 on the mask stage of the exposure apparatus, The process involves irradiating the phase shift mask with exposure light to transfer a transfer pattern onto a resist film provided on a substrate for a display device, A method for manufacturing a container, characterized by having the following features. [Effects of the Invention]

[0017] This invention provides a phase-shift mask that is advantageously suited to the exposure environment of masks used in the manufacture of display devices and offers excellent transfer resolution for fine hole patterns. [Brief explanation of the drawing]

[0018] [Figure 1] This is a schematic plan view of a phase shift mask in an embodiment of the present invention. [Figure 2] This is an enlarged view of the main part (region A in Figure 1) showing an example of a phase shift mask. [Figure 3] Figure 1 shows a magnified view of a key part illustrating another example of a phase shift mask. [Figure 4] This is a schematic cross-sectional view showing an example of a phase shift mask in an embodiment of the present invention. [Figure 5] This is a schematic cross-sectional view showing another example of a phase shift mask in an embodiment of the present invention. [Figure 6] This graph shows the results of an experimental example illustrating the present invention, illustrating the relationship between the difference between the radius of curvature RT of the light-transmitting portion and the radius of curvature RP of the phase-shift portion in the phase-shift mask, and the rate of change of DOF. [Figure 7] This graph shows the results of an experimental example illustrating the present invention, illustrating the relationship between the difference between the radius of curvature RT of the light-transmitting portion and the radius of curvature RP of the phase-shift portion in the phase-shift mask, and the rate of change of DOF. [Figure 8] This graph shows the results of an experimental example illustrating the present invention, illustrating the relationship between the difference between the radius of curvature RT of the light-transmitting portion and the radius of curvature RP of the phase-shift portion in the phase-shift mask, and the rate of change of DOF. [Figure 9] This graph shows the results of an experimental example illustrating the present invention, illustrating the relationship between the difference between the radius of curvature RT of the light-transmitting portion and the radius of curvature RP of the phase-shift portion in the phase-shift mask, and the rate of change of DOF. [Figure 10] This graph shows the results of an experimental example illustrating the present invention, illustrating the relationship between the difference between the radius of curvature RT of the light-transmitting portion and the radius of curvature RP of the phase-shift portion in the phase-shift mask, and the rate of change of DOF. [Figure 11] This graph shows the results of an experimental example illustrating the present invention, illustrating the relationship between the difference between the radius of curvature RT of the light-transmitting portion and the radius of curvature RP of the phase-shift portion in the phase-shift mask, and the rate of change of DOF. [Figure 12] This graph shows the results of an experimental example illustrating the present invention, illustrating the relationship between the difference between the radius of curvature RT of the light-transmitting portion and the radius of curvature RP of the phase-shift portion in the phase-shift mask, and the rate of change of DOF. [Figure 13] This graph shows the results of an experimental example illustrating the present invention, illustrating the relationship between the difference between the radius of curvature RT of the light-transmitting portion and the radius of curvature RP of the phase-shift portion in the phase-shift mask, and the rate of change of DOF. [Figure 14] This graph shows the results of an experimental example illustrating the present invention, illustrating the relationship between the difference between the radius of curvature RT of the light-transmitting portion and the radius of curvature RP of the phase-shift portion in the phase-shift mask, and the rate of change of DOF. [Modes for carrying out the invention]

[0019] First, let me describe the process leading to the completion of this invention. The inventors diligently studied the configuration of a phase-shift mask that is advantageously suited to the exposure environment of masks for display device manufacturing and has excellent transfer resolution for fine hole patterns. In a phase-shift mask, the phase-shift portion for forming contact holes is provided so as to surround the outer periphery of the translucent portion, where the translucent substrate is exposed in the shape of the hole. To improve the resolution of minute contact holes, it is desirable to ensure sufficient depth of focus (DOF) in the phase-shift mask in order to keep the uniformity of the CD (Critical Dimension) within a set tolerance range. Here, the depth of focus (DOF) is the size of the depth of focus required to be within ±10% of the target CD. If the DOF value can be increased, it will be less affected by the flatness of the material to be transferred (e.g., a panel substrate for a display device), allowing for the reliable formation of fine patterns and reducing CD variation.

[0020] In addition, in order to fully exhibit the phase shift effect, it is desirable to secure a certain degree of size of the light-transmitting portion and area (width) of the phase shift portion in the phase shift mask. However, it has been found that there are cases where the desired depth of focus (DOF) cannot be secured even for phase shift masks having the same size of the light-transmitting portion and area (width) of the phase shift portion. Therefore, the present inventor further studied and focused on the shapes of the outer periphery of the light-transmitting portion and the outer periphery of the phase shift portion. When the light-transmitting portion and the phase shift portion are formed by wet etching, the corner portions of the shapes are each rounded. The present inventor focused on the relationship between the radius of curvature of the corner portion of the outer periphery of the light-transmitting portion and the radius of curvature of the outer periphery of the phase shift portion, designed the size of the light-transmitting portion, the width of the phase shift portion, and the light transmittance within the allowable range, and then changed the radius of curvature of the phase shift portion and the radius of curvature of the light-transmitting portion to perform optical simulation. As a result, it has been found that by satisfying a certain relationship between the radius of curvature of the phase shift portion and the radius of curvature of the light-transmitting portion, the DOF can be improved and a phase shift mask excellent in transfer resolution can be configured. The phase shift mask of the present invention has been derived as a result of the above earnest research.

[0021] <Phase Shift Mask of Embodiment of the Present Invention> An example of the phase shift mask in an embodiment of the present invention will be described using the drawings. FIG. 1 is a plan schematic view of the phase shift mask in an embodiment of the present invention. FIG. 2 is an enlarged view of a main part showing an example of the phase shift mask shown in FIG. 1. As shown in FIG. 1, the phase shift mask 10 includes a light-transmitting portion 11, a phase shift portion 12, and a light-shielding portion 13 on a light-transmissive substrate 1. The light-transmitting portion 11 is formed by exposing the light-transmissive substrate 1 in a hole shape, the phase shift portion 12 is provided so as to surround the outer periphery of the light-transmitting portion 11, and the light-shielding portion 13 is provided so as to surround the outer periphery of the phase shift portion 12. Then, as shown in FIGS. and 2, the outer periphery of the light-transmitting portion 11 is a rectangular shape having a curve with a radius of curvature R T at the corner portions, and the outer periphery of the phase shift portion 12 is a rectangular shape having a curve with a radius of curvature R P at the corner portions, and the radius of curvature R T and the radius of curvature RP R T ≧R P The relationship is satisfied. Radius of curvature R T and radius of curvature R P R T >R P It is more preferable if the following relationship is satisfied. Also, the radius of curvature R T and radius of curvature R P R T ≥1.1 × R P It is more preferable if the relationship R is satisfied. T ≥1.2 × R P It is more desirable if the following conditions are met.

[0022] The phase shift mask 10 has a radius of curvature R at at least one of the four corners on the outer circumference of the phase shift portion 12. P The curve has such that at least the radius of curvature R of the phase shift portion 12 is one of the four corners on the outer circumference of the light-transmitting portion 11. P The corner with the curve and the adjacent corner have a radius of curvature R T It has a curve of R T and R P The above relationship (R T ≧R P It is required that the following conditions be met: That is, the radius of curvature R on the outer circumference of the phase shift section 12. P For corners with a curve, the radius of curvature R is set at the outer corner of the translucent portion 11 adjacent to that corner. T It has a curve and R T and R P The above relationship (R T ≧R P It is required that the following conditions be met. This increases the area of ​​the phase shift portion 12 at the corner, thereby achieving the effects of the present invention. On the other hand, for corners on the outer circumference of the phase shift portion 12 that do not have a curve (for example, corners composed only of straight lines), the corners on the outer circumference of the light-transmitting portion 11 adjacent to that corner may also be corners that do not have a curve, but it is preferable that they have a curve. All four corners on the outer circumference of the light-transmitting portion 11 have a radius of curvature R T The curve has a radius of curvature R at at least one of the four corners on the outer circumference of the phase shift portion 12. P The curve has the above relationship (RT ≧R P It is preferable that the following conditions are met. Furthermore, it is preferable that multiple of the four corners on the outer circumference of the light-transmitting portion 11 have a radius of curvature R. T If the curve has the radius of curvature R of each corner, T It is preferable that the values ​​of are the same, but it is not limited to this, and the radius of curvature R of each corner T The values ​​themselves may be different (for example, the radius of curvature R of the two corners on the outer circumference of the light-transmitting portion 11). T R T1 , R T2 (These may be different values.) Radius of curvature R of the corners on the outer circumference of the phase shift section 12 P The same applies to (for example, the radius of curvature R of the two corners on the outer circumference of the phase shift section 12). P R P1 , R P2 (These may be different values.) Also, if multiple corners of the four corners on the outer circumference of the light-transmitting portion 11 have a radius of curvature R T The curve has such that multiple corners among the four corners on the outer circumference of the phase shift section 12 have a radius of curvature R P If there are R T and R P The above relationship (R T ≧R P It is sufficient that the above conditions are met, and the above relationship does not need to be met in corners that are not adjacent to each other (for example, two corners of the outer circumference of the phase shift section 12 have different R values). P1 , R P2 Radius of curvature R P The corner portion has a value R, and two corner portions of the outer circumference of the light-transmitting portion 11 have a value R P1 , R P2 Radius of curvature R P Each corner having a different value R is adjacent to it. T1 , R T2 Radius of curvature R T In the case of a corner having R, in adjacent corners T1 ≧R P1 , R T2 ≧R P2 It is sufficient that the following conditions are met, and in corners that are not adjacent to each other, R T1 <R P2 , RT2 <R P1 (This is acceptable.)

[0023] The outer periphery of the light-transmitting portion 11 and the phase-shift portion 12 has a radius of curvature R at its four corners. T , R P It is a quadrilateral shape (rounded quadrilateral shape) having curves at each of its four corners, and as a quadrilateral shape, it is a rectangle or square with a radius of curvature R at each of its four corners. T It is more preferable that the shape is a rounded rectangle or rounded square with curved corners. In this invention, the quadrilateral shape only needs to have four straight sections in the up, down, left, and right directions when viewed from above, and there are no particular limitations on the ratio of the curved corner sections to the straight sections of the quadrilateral shape. For example, a roughly circular or elliptical shape in which the curved corner sections are larger than the straight sections of the quadrilateral shape is also included in the quadrilateral shape of this invention. These shapes can be confirmed, for example, using an optical microscope.

[0024] The size of the translucent portion 11 is not limited, but it can be calculated as the average of the distance (length) between two points where the vertical imaginary line intersects the outer circumference of the translucent portion 11 (the boundary between the translucent portion 11 and the phase-shift portion 12) at the top and bottom of the vertical imaginary line, and the distance (length) between two points where the horizontal imaginary line intersects the outer circumference of the translucent portion 11 (the boundary between the translucent portion 11 and the phase-shift portion 12) at the left and right of the horizontal imaginary line. The width of the phase shift section 12 is not limited, but it can be calculated as the average value of the distance between the vertical and horizontal straight sections of the phase shift section when imaginary cross lines are drawn vertically and horizontally from the centroid position of the translucent section 11 in a plan view (the average value of the four widths in the vertical, horizontal, and vertical directions).

[0025] radius of curvature R T , R PThe size is not limited, but in a plan view, perpendicular lines can be connected between the portions deviating from the straight line portion, and based on the intersection point, the average value of the respective distances can be calculated as the radius of curvature. This will be described using FIG. 3. FIG. 3 is an enlarged view of a main part showing another example of the phase shift mask shown in FIG. 1. As shown in FIG. 3, in the light transmission portion 11, the size of the perpendicular line in the vertical direction deviating from the straight line portion is R T2 and the size of the perpendicular line in the horizontal direction deviating from the straight line portion is R T1 Therefore, the radius of curvature R T of the light transmission portion 11 is (R T1 +R T2 ) / 2. Similarly, in the phase shift portion 12, the size of the perpendicular line in the vertical direction deviating from the straight line portion is R P2 and the size of the perpendicular line in the horizontal direction deviating from the straight line portion is R P1 Therefore, the radius of curvature R P of the phase shift portion 12 is (R P1 +R P2 ) / 2.

[0026] And, as shown in FIGS. 1 to 3, when the radius of curvature R T and the radius of curvature R P satisfy the relationship of R T ≧R P , the distance between the corner portion of the outer periphery of the phase shift portion 12 and the corner portion of the outer periphery of the light transmission portion 11 can be made larger than the distance (the width of the phase shift portion 12) between the straight line portion of the outer periphery of the phase shift portion 12 and the straight line portion of the outer periphery of the light transmission portion 11 (the straight line portion of the inner periphery of the phase shift portion 12). Thereby, it can be understood that the phase shift portion 12 exhibits a high phase shift effect not only between the straight line portions of the inner periphery and the outer periphery of the phase shift portion 12 but also at the corner portions.

[0027] From the viewpoint of forming a fine contact hole, the size of the light transmission portion 11 is preferably 4 μm or less, and more preferably 3 μm or less. Also, the size of the light transmission portion 11 is preferably 0.8 μm or more. Further, the radius of curvature R T of the light transmission portion 11 is the radius of curvature of the corner portion of the phase shift portion 12P in relation to (R T ≥ R P ), it is preferably 0.4 μm or more. The radius of curvature R of the light-transmitting portion 11 T is preferably less than half of the size of the light-transmitting portion 11.

[0028] The width of the phase shift portion 12 is preferably smaller than the size of the light-transmitting portion 11. Also, from the viewpoint of enhancing the phase shift effect, the width of the phase shift portion 12 is preferably 0.5 μm or more, and more preferably 0.6 μm or more. Further, from the viewpoint of suppressing the film reduction of the resist film (the resist film on the substrate when the exposure transfer of the transfer pattern is performed on the substrate for the display device using the phase shift mask), the width of the phase shift portion 12 is preferably 2.0 μm or less, and more preferably 1.8 μm or less.

[0029] The configuration of the phase shift mask 10 in the present embodiment will be described with reference to FIGS. 4 and 5. The phase shift mask 10 shown in FIG. 4 is of a phase shift film underlay (pre-attached) type (a type in which the phase shift film 2A is formed first under the light-shielding film 3A) in which a light-shielding pattern is formed on the phase shift film 2A on which a phase shift pattern is formed. In the pre-attached type of phase shift mask 10, an etching stopper film may be interposed between the phase shift film 2A and the light-shielding film 3. In this case, the pattern of the etching stopper film is preferably the same pattern as the light-shielding pattern.

[0030] On the other hand, the phase shift mask 10 shown in FIG. 5 is of a phase shift film overlay (post-attached) type (a type in which the phase shift film 2B is formed later on the light-shielding film 3B) in which a phase shift film 2B on which a phase shift pattern is formed is formed on the light-shielding film 3B on which a light-shielding pattern is formed and on the translucent substrate 1. When there is no particular need to distinguish between the phase shift films 2A, 2B and the light-shielding films 3A, 3B, they may be described as the phase shift film 2 and the light-shielding film 3.

[0031] Preferably, the phase-shift portion 12 consists of a phase-shift film 2, and the light-transmitting portion 11 has a configuration in which a part of the phase-shift film 2 is removed in the shape of a hole, exposing the light-transmitting substrate 1. This phase-shift film 2 is a phase-shift film 2 (hereinafter sometimes simply referred to as "phase-shift film 2") on which a transfer pattern (phase-shift pattern) including the light-transmitting portion 11 is formed.

[0032] The translucent substrate 1 is transparent to exposure light. Assuming no surface reflection loss, the translucent substrate 1 has a transmittance of 85% or more, preferably 90% or more, to exposure light. The translucent substrate 1 is made of a material containing silicon and oxygen, and can be composed of glass materials such as synthetic quartz glass, quartz glass, aluminosilicate glass, soda-lime glass, and low thermal expansion glass (SiO2-TiO2 glass, etc.). The main surface of the translucent substrate 1 (the surface on which the phase shift pattern, etc., is provided) is rectangular with sides of 300 mm or more. In the case of a substrate with such a large main surface size, it is difficult to achieve high flatness of the main surface, so a phase shift mask with a large DOF is preferable.

[0033] The pre-applied phase-shift film 2A can be made of a material containing a transition metal and silicon (Si). Suitable transition metals include molybdenum (Mo), tantalum (Ta), tungsten (W), titanium (Ti), and zirconium (Zr), with titanium and molybdenum being more preferred. The phase-shift film 2A may also use a material containing chromium (Cr), for example, a chromium-based material containing Cr and at least one of oxygen (O) or nitrogen (N) can be used. Specifically, CrO, CrN, CrON, etc., are examples. The phase-shift film 2A is preferably wet-etchable. On the other hand, the post-applied phase-shift film 2B is preferably made of the above-mentioned chromium-based material from the viewpoint of using the same wet etching solution as the light-shielding film 3B, but is not limited to this, and can also be made of a material containing a transition metal and silicon (Si).

[0034] Furthermore, in the configuration in which an etching stopper film is interposed between the phase shift film 2A and the light-shielding film 3, it is preferable to use materials for the phase shift film 2A and the light-shielding film 3 that can be patterned with the same wet etching solution, and to use a material for the etching stopper film that exhibits etching selectivity between the materials for the phase shift film 2A and the light-shielding film 3. For example, it is preferable to use materials containing chromium for the phase shift film 2A and the light-shielding film 3, and a material containing a transition metal and silicon for the etching stopper film.

[0035] For exposure light, for example, light with a wavelength range of 300 to 500 nm can be used. As the light source of an exposure apparatus for manufacturing display devices, for example, a light source including one or more of i-line, h-line, and g-line (e.g., a high-pressure mercury lamp) can be suitably used. The representative wavelength of the exposure light can be any wavelength included in the above wavelength range. Furthermore, as the pattern becomes finer and it is desirable to shift the center of gravity of the exposure light wavelength range to the shorter wavelength side, light with a shorter wavelength range than the above wavelength range (for example, 250-400 nm) can be used as the exposure light. For example, light in the shorter wavelength range that includes two or more of 313 nm, 334 nm, and 365 nm can be applied as the exposure light. In addition, light of a single wavelength i-line (365 nm) can also be applied as the exposure light. Thus, it is preferable that the exposure light includes at least light with a wavelength of 365 nm. In this specification, unless otherwise specified, the i-line (365 nm) is used as an example of a representative wavelength.

[0036] The numerical aperture (NA) of the exposure light is preferably in the range of 0.08 to 0.20, and more preferably in the range of 0.08 to 0.15. Generally, increasing the NA of an optical system increases its resolution. However, simply replacing exposure equipment used in the field of display device manufacturing with equipment that has a higher NA is not necessarily advantageous in terms of cost or technology. For example, changing an existing exposure equipment to one with a higher NA would mean a huge investment for a display panel manufacturer. In addition, increasing the NA has disadvantages such as a decrease in DOF. In phase shift masks for display devices, which have a larger area than photomasks for LSI manufacturing, this can lead to a decrease in production stability and yield. By setting the numerical aperture (NA) within the above range, it is possible to ensure good resolution while suppressing a decrease in production stability and yield.

[0037] The phase-shift film 2 has a phase-shift effect with respect to the representative wavelength of the exposure light. That is, there is a phase difference Φ between the exposure light that has passed through the phase-shift film 2 and the exposure light that has passed through the air over a distance equal to the thickness of the phase-shift film 2. P A phase difference Φ occurs. P The phase shift is preferably approximately 180 degrees. In this specification, approximately 180 degrees means 150 degrees or more and 210 degrees or less, preferably 160 degrees or more and 200 degrees or less, and more preferably 170 degrees or more and 190 degrees or less. Furthermore, it is preferable that the phase shift film 2 has a phase difference of approximately 180 degrees with respect to all of the main wavelengths (e.g., i-line, h-line, g-line) included in the exposure light.

[0038] The transmittance of the phase-shift film 2 to the exposure light satisfies the required value for the phase-shift film 2. Transmittance T of the phase-shift film 2 P The transmittance T of the phase shift film 2 is preferably 5% or more, and preferably 10% or more, relative to the light of the representative wavelength contained in the exposure light. P It is preferable that this is 50% or less, and more preferably 40% or less, of the light of a representative wavelength included in the exposure light.

[0039] The thickness of the phase-shift film 2 is preferably 200 nm or less, more preferably 180 nm or less, and even more preferably 150 nm or less, in order to ensure optical performance. Furthermore, the thickness of the phase-shift film 2 is preferably 50 nm or more, and more preferably 60 nm or more, in order to ensure the desired transmittance.

[0040] The phase-shift film 2 can be formed by known deposition methods such as sputtering. The transfer pattern can also be formed by known methods such as wet etching.

[0041] As shown in Figure 4, in the pre-attached type, the light-shielding film 3A is placed on top of the phase-shift film 2A. On the other hand, as shown in Figure 5, in the post-attached type, the light-shielding film 3B is placed below the phase-shift film 2B. In either case, the light-shielding portion 13 is formed by laminating the phase-shift film 2 and the light-shielding film 3. The light-shielding film 3A is positioned above the phase-shift film 2A. Preferably, the light-shielding film 3A is made of a material with different etching selectivity than the phase-shift film 2A. On the other hand, in the case of a post-installation type, since the light-shielding film 3B having a light-shielding pattern can be formed on the translucent substrate 1, and then the phase-shift film 2B can be laminated and the phase-shift pattern formed, it is not necessary for the phase-shift film 2B and the light-shielding film 3B to have etching selectivity.

[0042] The light-shielding film 3 (3A, 3B) is preferably composed of a chromium-based material containing chromium (Cr). More preferably, the light-shielding film 3 is composed of a material that contains chromium and is substantially silicon-free. Substantially silicon-free means that the silicon content is less than 2%. More specifically, chromium-based materials include materials consisting of pure chromium (Cr), or materials containing chromium (Cr) and at least one of oxygen (O), nitrogen (N), and carbon (C). Furthermore, chromium-based materials include materials containing chromium (Cr), at least one of oxygen (O), nitrogen (N), and carbon (C), and also containing fluorine (F). For example, materials that constitute the light-shielding film 3 include Cr, CrO, CrN, CrF, CrCO, CrCN, CrON, CrCON, and CrCONF. On the other hand, in the case of a configuration in which an etching stopper film is interposed between the phase shift film 2A and the light-shielding film 3, if the phase shift film 2A is made of a material containing a transition metal and silicon, it is preferable that the light-shielding film 3 is also made of a material containing a transition metal and silicon. In this case, it is preferable to use a material containing chromium for the etching stopper film.

[0043] The light-shielding film 3 can be formed by known film deposition methods such as sputtering.

[0044] The light-shielding film 3 has the function of blocking the transmission of exposure light, and in the light-shielding portion 13 where the phase-shift film 2 and the light-shielding film 3 are laminated, the optical density (OD) with respect to exposure light is preferably 2 or more, more preferably 3 or more, even more preferably 3.5 or more, and even more preferably 4 or more.

[0045] The phase shift mask 10 in the embodiment of the present invention, having the above-described configuration, can be an excellent phase shift mask that is advantageously suited to the exposure environment of a mask for manufacturing a display device and can stably transfer a fine hole pattern.

[0046] Next, a method for manufacturing the phase shift mask 10 of the present invention will be described. When manufacturing the phase shift mask 10 shown in Figure 4, a mask blank is prepared on which a phase shift film and a light-shielding film are formed on a translucent substrate. The specific configuration of the translucent substrate, phase shift film, and light-shielding film formed on the mask blank is the same as that of the translucent substrate 1, phase shift film 2A, and light-shielding film 3A formed on the phase shift mask 10, except that the phase shift pattern and light-shielding pattern are not formed.

[0047] First, a pattern consisting of light-transmitting portions in the shape of holes is formed on the phase-shift film and the light-shielding film. For example, by forming a resist film on the light-shielding film and using the resist film pattern including the holes formed from the resist film as a mask, the phase-shift film and the light-shielding film can be wet-etched to form a pattern in the shape of holes on the phase-shift film and the light-shielding film. In this way, a light-transmitting portion 11 is formed in which the light-transmitting substrate 1 is exposed in the shape of holes.

[0048] Then, the resist film is peeled off, a new resist film is formed on the light-shielding film, and the light-shielding film is wet-etched using the resist film pattern, which includes the phase-shift portion formed from the resist film, as a mask, thereby forming a light-shielding film 3A having a light-shielding pattern. In this way, the phase-shift portion 12 can be formed by exposing the phase-shift film 2A so as to surround the outer periphery of the light-transmitting portion 11, and the light-shielding portion 13 can be formed so as to surround the outer periphery of the phase-shift portion 12. In this manufacturing method, by adjusting the wet etching time and the shape of the pattern formed on the resist film, the radius of curvature R T and radius of curvature R P However, R T ≧R P The outer corners of the phase shift portion 12 and the outer corners of the light-transmitting portion 11 can be formed in such a way that the relationship is satisfied. In this way, the phase shift mask 10 shown in Figure 4 can be manufactured.

[0049] When manufacturing the phase shift mask 10 shown in Figure 5, a mask blank is prepared in which a light-shielding film is formed on a translucent substrate. The specific configuration of the translucent substrate and light-shielding film formed on the mask blank is the same as that of the translucent substrate 1 and light-shielding film 3B formed on the phase shift mask 10, except that a light-shielding pattern is not formed.

[0050] First, a light-shielding pattern is formed on the light-shielding film. For example, a resist film is formed on the light-shielding film, and the resist film pattern, which includes the light-shielding pattern formed from the resist film, is used as a mask to wet etch the light-shielding film, thereby forming a light-shielding film 3B having a light-shielding pattern.

[0051] Then, the resist film is peeled off and a phase-shift film is formed on the light-shielding film 3B and the exposed translucent substrate 1. A new resist film is formed on the phase-shift film, and the phase-shift film is wet-etched using the resist film pattern, which includes the phase-shift portion formed from the resist film, as a mask, thereby forming a phase-shift film 2B having a phase-shift pattern. In this way, the phase-shift portion 12 can be formed by exposing the phase-shift film 2B so as to surround the outer periphery of the translucent portion 11, and the light-shielding portion 13 can be formed so as to surround the outer periphery of the phase-shift portion 12. In this manufacturing method as well, by adjusting the wet etching time and the shape of the pattern formed on the resist film, the radius of curvature R can be adjusted. T and radius of curvature R P However, R T ≧R P The outer corners of the phase shift portion 12 and the outer corners of the light-transmitting portion 11 can be formed in such a way that the relationship is satisfied. In this way, the phase shift mask 10 shown in Figure 5 can be manufactured.

[0052] <Method for manufacturing a display device> A method for manufacturing the display device of this embodiment will now be described. The method for manufacturing the display device of this embodiment includes the steps of: placing the phase shift mask described in the above embodiment on the mask stage of an exposure apparatus; and irradiating the phase shift mask with exposure light to transfer a transfer pattern to a resist film provided on a substrate for the display device. The following describes each step in detail.

[0053] In the placement process, the phase-shift mask of the above-described embodiment is placed on the mask stage of the exposure apparatus. Here, the phase-shift mask is positioned to face the resist film formed on the substrate for the display device via the projection optical system of the exposure apparatus.

[0054] In the pattern transfer process, exposure light is irradiated onto a phase shift mask to transfer a transfer pattern, including a thin-film pattern for pattern formation, onto a resist film formed on a substrate for a display device. The exposure light is composite light containing multiple wavelengths selected from the 313nm to 436nm wavelength range, monochromatic light selected by filtering out a certain wavelength range from the 313nm to 436nm wavelength range, or monochromatic light emitted from a light source having a wavelength range of 313nm to 436nm. For example, the exposure light is composite light containing at least one of the i-line, h-line, and g-line, or monochromatic light of the i-line. By using composite light as the exposure light, the exposure light intensity can be increased and throughput can be improved. Therefore, the manufacturing cost of the display device can be reduced. The numerical aperture NA of the exposure light is preferably in the range of 0.08 to 0.20, and more preferably in the range of 0.08 to 0.15.

[0055] According to the method for manufacturing a display device of this embodiment, it is possible to manufacture a high-resolution display device with high resolution and fine contact holes.

[0056] <Example of experiment> The transfer performance of the phase shift mask of this embodiment was compared and evaluated by optical simulation. Specifically, optical simulation was performed to determine the transfer performance of a phase shift mask having a transfer pattern for forming a hole pattern with a diameter of 1.9 μm on a transfer target (for example, a resist film provided on a substrate for a display device) when exposure conditions were set. The exposure conditions were set to an numerical aperture (NA) of 0.11 and a single wavelength of exposure light, i-line (wavelength 365 nm). Here, the phase difference of the phase shift portion was set to 180 degrees. The results of experimental examples illustrating the present invention will be explained using Figures 6-12. Figures 6-10 show the radius of curvature R of the light-transmitting portion in the phase shift mask. T and the radius of curvature R of the phase shift portion P This graph shows the relationship between the difference and the rate of change of DOF. In Figures 6-12, the horizontal axis of the graph is R T and R P The difference (R T -R P The vertical axis of the graph represents the rate of change of DOF [%], with the horizontal axis representing the radius of curvature R of the transparent portion at the origin of the graph. T and the radius of curvature R of the phase shift portion P These values ​​are equal, and the ratio on the vertical axis is calculated based on the DOF value [μm] at this time. In Figures 6-12, the R defined in this invention is shown. T ≧R P The region that satisfies this relationship is the right half of the graph, including the origin. Here, in all samples in Figures 6-12, the DOF value corresponding to the origin of the graph was within the acceptable range. Note that the rate of change of DOF [%] is R T =R P This is the rate of change of DOF, with the DOF at the time of [specific condition] as the reference. In other words, the same sample (with the same radius of curvature R) as described later. p In the data under the conditions, the difference (R T -R P ) is 0 (R T =R P DOF in the case of D B , a specific difference (RT-RP) (however, R T ≠RP DOF in the case of D TP In that case, the rate of change D of DOF at that specific difference (RT-RP) V (D TP -D B ) / D B It is calculated using the formula ×100[%].

[0057] In the experimental example shown in Figure 6, the transmittance of the phase shift section 12 was set to 5%, the width of the phase shift section 12 was set to 1.2 μm, and the size of the light-transmitting section 11 was set to 2.0 μm. Samples a1, a2, a3, and a4 in Figure 6 have a radius of curvature R of the phase shift section 12. P These were set to 0.4 μm, 0.6 μm, 0.8 μm, and 1.0 μm, respectively. Then, for each sample a1 to a4, the radius of curvature R of the light-transmitting portion 11 T Let these be 0.4 μm, 0.6 μm, 0.8 μm, and 1.0 μm respectively, R T and R P The difference (R T -R P The [μm] was calculated, and the percentage change in DOF for each was also calculated. As shown in Figure 6, in all samples a1 to a4, R T and R P When the difference is 0 or greater, the DOF change rate increases, indicating that resolution can be improved. On the other hand, in all samples a1 to a4, R T and R P It was found that when the difference is less than 0, the DOF change rate decreases, which may impair resolution.

[0058] In the experimental example shown in Figure 7, the transmittance of the phase shift section 12 was set to 10%, the width of the phase shift section 12 was set to 1.2 μm, and the size of the light-transmitting section 11 was set to 2.0 μm. Samples b1, b2, b3, and b4 in Figure 7 have a radius of curvature R of the phase shift section 12. P These were set to 0.4 μm, 0.6 μm, 0.8 μm, and 1.0 μm, respectively. Then, for each sample b1 to b4, the radius of curvature R of the light-transmitting portion 11 T Let these be 0.4 μm, 0.6 μm, 0.8 μm, and 1.0 μm respectively, R T and R P The difference (R T -R P The [μm] was calculated, and the percentage change in DOF for each was also calculated. As shown in Figure 7, in all samples b1 to b4, R T and R P It was found that when the difference is 0 or greater, the DOF change rate increases, and the resolution can be improved. On the other hand, in all samples b1 to b4, R T and R P It was found that when the difference is less than 0, the DOF change rate decreases, which may impair resolution.

[0059] In the experimental example shown in Figure 8, the transmittance of the phase shift section 12 was set to 20%, the width of the phase shift section 12 was set to 1.2 μm, and the size of the light-transmitting section 11 was set to 2.0 μm. Samples c1, c2, c3, and c4 in Figure 8 have a radius of curvature R of the phase shift section 12. P These were set to 0.4 μm, 0.6 μm, 0.8 μm, and 1.0 μm, respectively. Then, for each sample c1 to c4, the radius of curvature R of the light-transmitting portion 11 T Let these be 0.4 μm, 0.6 μm, 0.8 μm, and 1.0 μm respectively, R T and R P The difference (R T -R P The [μm] was calculated, and the percentage change in DOF for each was also calculated. As shown in Figure 8, in all samples c1 to c4, R T and R P It was found that when the difference is 0 or greater, the DOF change rate increases, and the resolution can be improved. On the other hand, in all samples c1 to c4, R T and R PIt was found that when the difference is less than 0, the DOF change rate decreases, which may impair resolution.

[0060] In the experimental example shown in Figure 9, the transmittance of the phase shift section 12 was set to 10%, the width of the phase shift section 12 was set to 1.2 μm, and the size of the light-transmitting section 11 was set to 2.2 μm. Samples d1, d2, d3, and d4 in Figure 9 have a radius of curvature R of the phase shift section 12. P These were set to 0.4 μm, 0.6 μm, 0.8 μm, and 1.0 μm, respectively. Then, for each sample d1 to d4, the radius of curvature R of the light-transmitting portion 11 T Let these be 0.4 μm, 0.6 μm, 0.8 μm, and 1.0 μm respectively, R T and R P The difference (R T -R P The [μm] was calculated, and the percentage change in DOF for each was also calculated. As shown in Figure 9, in all samples d1 to d4, R T and R P It was found that when the difference is 0 or greater, the DOF change rate increases, and the resolution can be improved. On the other hand, in all samples d1 to d4, R T and R P It was found that when the difference is less than 0, the DOF change rate decreases, which may impair resolution.

[0061] In the experimental example shown in Figure 10, the transmittance of the phase-shift section 12 was set to 10%, the width of the phase-shift section 12 was set to 1.2 μm, and the size of the light-transmitting section 11 was set to 2.4 μm. Samples e1, e2, e3, and e4 in Figure 10 have a radius of curvature R of the phase-shift section 12. P These were set to 0.4 μm, 0.6 μm, 0.8 μm, and 1.0 μm, respectively. Then, for each sample e1 to e4, the radius of curvature R of the light-transmitting portion 11 T Let these be 0.4 μm, 0.6 μm, 0.8 μm, and 1.0 μm respectively, R T and R P The difference (RT -R P The [μm] was calculated, and the percentage change in DOF for each was also calculated. As shown in Figure 10, in all samples e1 to e4, R T and R P When the difference is 0 or greater, the DOF change rate increases, indicating that resolution can be improved. On the other hand, in all samples e1 to e4, R T and R P It was found that when the difference is less than 0, the DOF change rate decreases, which may impair resolution.

[0062] In the experimental example shown in Figure 11, the transmittance of the phase-shift section 12 was set to 10%, the width of the phase-shift section 12 to 0.8 μm, and the size of the light-transmitting section 11 to 2.0 μm. Samples f1, f2, f3, and f4 in Figure 11 have a radius of curvature R of the phase-shift section 12. P These were set to 0.4 μm, 0.6 μm, 0.8 μm, and 1.0 μm, respectively. Then, for each sample f1 to f4, the radius of curvature R of the light-transmitting portion 11 T Let these be 0.4 μm, 0.6 μm, 0.8 μm, and 1.0 μm respectively, R T and R P The difference (R T -R P The [μm] was calculated, and the percentage change in DOF for each was also calculated. As shown in Figure 11, in all samples f1 to f4, R T and R P It was found that when the difference is 0 or greater, the DOF change rate increases, and the resolution can be improved. On the other hand, in all samples f1 to f4, R T and R P It was found that when the difference is less than 0, the DOF change rate decreases, which may impair resolution.

[0063] In the experimental example shown in Figure 12, the transmittance of the phase-shift section 12 was set to 10%, the width of the phase-shift section 12 was set to 1.0 μm, and the size of the light-transmitting section 11 was set to 2.0 μm. Samples g1, g2, g3, and g4 in Figure 12 have a radius of curvature R of the phase-shift section 12. P These were set to 0.4 μm, 0.6 μm, 0.8 μm, and 1.0 μm, respectively. Then, for each sample g1 to g4, the radius of curvature R of the light-transmitting portion 11 T Let these be 0.4 μm, 0.6 μm, 0.8 μm, and 1.0 μm respectively, R T and R P The difference (R T -R P The [μm] was calculated, and the percentage change in DOF for each was also calculated. As shown in Figure 12, in all samples g1 to g4, R T and R P It was found that when the difference is 0 or greater, the DOF change rate increases, and the resolution can be improved. On the other hand, in all samples g1 to g4, R T and R P It was found that when the difference is less than 0, the DOF change rate decreases, which may impair resolution.

[0064] On the other hand, optical simulations were performed under the same conditions as above, except that the numerical aperture (NA) of the exposure conditions was changed from 0.11. In the experimental example shown in Figure 13, the optical simulation was performed under the same conditions as the experimental example in Figure 7, except that the numerical aperture NA was changed to 0.08 (transmittance of the phase shift section 12 is 10%, width of the phase shift section 12 is 1.2 μm, size of the light-transmitting section 11 is 2.0 μm). Samples h1, h2, h3, and h4 in Figure 13 have a radius of curvature R of the phase shift section 12. P These were set to 0.4 μm, 0.6 μm, 0.8 μm, and 1.0 μm, respectively. Then, for each sample h1 to h4, the radius of curvature R of the light-transmitting portion 11 T Let these be 0.4 μm, 0.6 μm, 0.8 μm, and 1.0 μm respectively, R Tand R P The difference (R T -R P The [μm] was calculated, and the percentage change in DOF for each was also calculated. As shown in Figure 13, in all samples h1 to h4, R T and R P It was found that when the difference is 0 or greater, the DOF change rate increases, and the resolution can be improved. On the other hand, in all samples h1 to h4, R T and R P It was found that when the difference is less than 0, the DOF change rate decreases, which may impair resolution.

[0065] In the experimental example shown in Figure 14, the optical simulation was performed under the same conditions as the experimental example in Figure 7, except that the numerical aperture NA was changed to 0.12 (transmittance of the phase-shifted section 12 was 10%, width of the phase-shifted section 12 was 1.2 μm, and size of the light-transmitting section 11 was 2.0 μm). Samples i1, i2, i3, and i4 in Figure 14 have a radius of curvature R of the phase-shifted section 12. P These were set to 0.4 μm, 0.6 μm, 0.8 μm, and 1.0 μm, respectively. Then, for each sample i1 to i4, the radius of curvature R of the light-transmitting portion 11 T Let these be 0.4 μm, 0.6 μm, 0.8 μm, and 1.0 μm respectively, R T and R P The difference (R T -R P The [μm] was calculated, and the percentage change in DOF for each was also calculated. As shown in Figure 13, in all samples i1 to i4, R T and R P It was found that when the difference is 0 or greater, the DOF change rate increases, and the resolution can be improved. On the other hand, in all samples h1 to h4, R T and R P It was found that when the difference is less than 0, the DOF change rate decreases, which may impair resolution.

[0066] Furthermore, in the experimental examples shown in Figures 6 and 8-12, optical simulations were performed by changing the numerical aperture (NA) to 0.08 and 0.12, respectively. The simulation results for all of these were similar to those for the other experimental examples, R T and R P When the difference is 0 or greater, the DOF change rate increases, and the resolution can be improved. T and R P It was found that when the difference is less than 0, the DOF change rate decreases, which may impair resolution.

[0067] Furthermore, optical simulations were also performed for cases where the exposure light wavelength was shorter (334 nm) and longer (405 nm). The simulation results for all cases, as with the other experimental examples, showed R T and R P When the difference is 0 or greater, the DOF change rate increases, and the resolution can be improved. T and R P It was found that when the difference is less than 0, the DOF change rate decreases, which may impair resolution. [Explanation of Symbols]

[0068] 1 Translucent substrate 2 (2A, 2B) Phase-shift film (phase-shift pattern) 3 (3A, 3B) Light-shielding film (light-shielding pattern) 10 Phase Shift Mask 11 Translucent part 12 Phase shift section 13 Light-shielding part

Claims

1. A phase shift mask comprising a light-transmitting portion, a phase-shifting portion, and a light-shielding portion on a light-transmitting substrate, The light-transmitting portion is formed by exposing a light-transmitting substrate in the shape of a hole. The phase shift portion is provided so as to surround the outer periphery of the light-transmitting portion, The light-shielding portion is provided so as to surround the outer circumference of the phase-shift portion. The outer circumference of the light-transmitting portion has a radius of curvature R at at least one corner. Ｔ It is a quadrilateral shape with curves, The outer circumference of the phase shift portion has the radius of curvature R Ｔ The corner having a curve and the adjacent corner have a radius of curvature R Ｐ It is a quadrilateral shape having at least the curve, The radius of curvature R Ｔ and the radius of curvature R Ｐ R Ｔ ≥ R Ｐ Satisfying the relationship A phase shift mask characterized by the following features.

2. The width of the phase shift portion is smaller than the size of the light-transmitting portion. The phase shift mask according to claim 1, characterized in that it is as described above.

3. The phase shift portion has a transmittance of 5% or more to exposure light. The phase difference between the exposure light transmitted through the phase shift portion and the exposure light transmitted through the light-transmitting portion is 150 degrees or more and 210 degrees or less. A phase shift mask according to feature 1 or 2.

4. The phase shift mask according to claim 1 or 2, characterized in that the light-shielding portion has an optical density OD of 2 or more with respect to exposure light.

5. The phase shift mask according to claim 2, characterized in that the width of the phase shift portion is 0.5 μm or more and 2.0 μm or less.

6. The phase shift mask according to claim 2, characterized in that the size of the light-transmitting portion is 4 μm or less.

7. Radius of curvature R of the light-transmitting portion Ｔ The phase shift mask according to claim 1 or 2, characterized in that the particle size is 0.4 μm or larger.

8. The phase shift mask according to claim 1 or 2, characterized in that the phase shift portion consists of a phase shift film, and the light-transmitting portion has a configuration in which a part of the phase shift film is removed in the shape of a hole to expose a light-transmitting substrate.

9. The phase shift mask according to claim 8, characterized in that the light-shielding portion is formed by laminating the phase shift film and the light-shielding film.

10. A step of placing the phase shift mask according to claim 1 or 2 on the mask stage of an exposure apparatus, The process involves irradiating the phase shift mask with exposure light to transfer a transfer pattern onto a resist film provided on a substrate for a display device, A method for manufacturing a container, characterized by having the following features.

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