Phase shift mask and method for manufacturing 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 phase shift mask and a method for manufacturing a display device.

Background Art

[0002] In recent years, in display devices such as FPDs (Flat Panel Displays) represented by OLEDs (Organic Light Emitting Diodes), high definition and high-speed display have been rapidly progressing along with large screen size, wide viewing angle, and flexibility such as foldability. One of the elements required for this high definition and high-speed display is to fabricate electronic circuit patterns such as fine and highly dimensionally accurate elements and wirings. Photolithography is often used for patterning this electronic circuit for the display device. Therefore, a phase shift mask for manufacturing a display device in which a fine and highly accurate pattern is formed is required. This phase shift mask is formed by a halftone film having a low transmittance and a phase shift amount of 180 degrees in a portion corresponding to the light-shielding portion of a binary mask.

[0003] For example, Patent Document 1 describes a transmissive portion 1 formed of a substrate transparent to exposure light, a semi-transmissive 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 light wavelength λ and k is an odd integer) and a transmittance with respect to the exposure light of 5 to 20%, a semi-transmissive portion 2 formed on the substrate around the transmissive portion 1, and an outer region portion 3 made of a light-shielding layer or a hardly transmissive layer laminated on the semi-transmissive phase shifter layer outside the region of the semi-transmissive portion 2, which constitutes a halftone type phase shift mask. In addition, Patent Document 2 describes a method for manufacturing a photomask, which includes a step of preparing a photomask blank formed by laminating a lower layer film and an upper layer film on a transparent substrate, an upper layer film preliminary etching step of etching the upper layer film using a resist pattern formed on the upper layer film as a mask, a lower layer film patterning step of etching the lower layer film 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 of side etching the upper layer film 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

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] For example, in the case of a thin film transistor (Thin Film Transistor, "TFT") used in the above display device, among the plurality of patterns constituting the TFT, if the contact hole formed in the interlayer insulating film does not ensure the function of connecting the upper and lower patterns, the correct operation cannot be guaranteed. On the other hand, in order to make the aperture ratio of the display device as large as possible to obtain a bright and power-saving display device, it is required that the diameter of the contact hole is sufficiently small. Along with this, it is desired to miniaturize (for example, less than 3 μm) the diameter of the hole pattern provided in the photomask for forming such a contact hole. For example, a hole pattern with a diameter of 2.5 μm or less, and further, a diameter of 2.0 μm or less is required, and it is considered that in the near future, the formation of a pattern with a diameter of less than 1.5 μm, which is smaller than this, will also be desired. Against this background, a manufacturing technology for a display device that can reliably transfer minute contact holes is required.

[0006] However, conventionally, it has been found that it is not easy to obtain a phase shift mask that is advantageously adapted to the exposure environment of a mask for manufacturing a display device and has excellent transfer resolution of a fine hole pattern, and a method for manufacturing a display device.

[0007] The present invention has been made to solve the above problems. That is, an object of the present invention is to obtain a phase shift mask that is advantageously adapted to the exposure environment of a mask for manufacturing a display device and has excellent transfer resolution of a fine hole pattern, and a method for manufacturing a display device.

Means for Solving the Problems

[0008] As means for solving the above problems, the present invention has the following configuration.

[0009] (Configuration 1) A phase shift mask provided with a light-transmitting portion, a phase shift portion, and a light-shielding portion on a light-transmitting substrate, wherein the light-transmitting portion is formed by exposing the light-transmitting substrate in a hole shape, 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 periphery of the phase shift portion, the outer periphery of the light-transmitting portion has a rectangular shape having a curve with a radius of curvature R T at at least one corner, the outer periphery of the phase shift portion has a rectangular shape having a curve with a radius of curvature R T at a corner adjacent to the corner having the curve, and at least having a curve with a radius of curvature R P at another corner, wherein the radius of curvature R T and the radius of curvature R P satisfy the relationship of R T ≧R P ; A phase shift mask characterized by this.

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

[0011] (Configuration 3) The phase shift portion has a transmittance of 5% or more with respect to the exposure light, and the phase difference generated between the exposure light transmitted through the phase shift portion and the exposure light transmitted through the light transmissive portion is 150 degrees or more and 210 degrees or less. The phase shift mask according to Configuration 1 or 2, characterized in that.

[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 the 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 transmissive portion is 4 μm or less.

[0014] (Configuration 7) The radius of curvature R of the light transmissive portion T is 0.4 μm or more. The phase shift mask according to Configuration 1 or 2, characterized in that.

[0015] (Configuration 8) The phase shift mask according to Configuration 1 or 2, characterized in that the phase shift portion is made of a phase shift film, and the light transmissive portion is formed by removing a part of the phase shift film in a hole shape to expose a light transmissive 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 a light shielding film.

[0016] (Configuration 10) A step of placing the phase shift mask according to Configuration 1 or 2 on a mask stage of an exposure apparatus, and a step of irradiating the phase shift mask with exposure light to transfer a transfer pattern to a resist film provided on a substrate for a display device. A method for manufacturing a display device, characterized by comprising.

Advantages of the Invention

[0017] To provide a phase shift mask that is advantageously adapted to the exposure environment of a mask for device manufacturing and has excellent resolution in transferring a fine hole pattern. BRIEF DESCRIPTION OF THE DRAWINGS

[0018]

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Embodiments for Carrying Out the Invention

[0019] First, the background leading to the completion of the present invention will be described. The inventor has intensively studied the configuration of a phase-shifting mask that is advantageously adapted to the exposure environment of a mask for manufacturing a display device and has excellent transfer resolution of a fine hole pattern. In a phase-shifting mask, the phase-shifting portion for forming a contact hole is provided so as to surround the outer periphery of a light-transmitting portion where a light-transmitting substrate is exposed in a hole shape. In order to improve the resolution of a minute contact hole, it is desirable to secure a sufficient depth of focus (DOF) in the phase-shifting mask in order to keep the uniformity of the CD (Critical Dimension) within a set allowable range. Here, the depth of focus (DOF) is the magnitude of the depth of focus for being within the range of ±10% with respect to the target CD. If the numerical value of the DOF can be increased, it is less affected by the flatness of the object to be transferred (for example, a panel substrate for a display device), a fine pattern can be surely formed, and the CD variation can be reduced.

[0020] In addition, in order to fully exhibit the phase shift effect, it is desirable to ensure a certain size of the light-transmitting portion and a certain area (width) of the phase shift portion in the phase shift mask. However, it has been found that even for phase shift masks with the same size of the light-transmitting portion and the same area (width) of the phase shift portion, it may not be possible to ensure the desired depth of focus (DOF). Therefore, the present inventor further studied and focused on the shapes of the outer peripheries of the light-transmitting portion and the phase shift portion. When the light-transmitting portion and the phase shift portion are formed by wet etching, the corner portions of their shapes each have a rounded shape. 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 corner portion of the outer periphery of the phase shift portion. After designing the size of the light-transmitting portion, the width of the phase shift portion, and the light transmittance within allowable ranges, optical simulations were performed by changing the radius of curvature of the phase shift portion and the radius of curvature of the light-transmitting portion. 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 intensive 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 with reference to 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. 1 and 2, the outer periphery of the light-transmitting portion 11 has a rectangular shape with a curve having a radius of curvature R T at the corner portions, and the outer periphery of the phase shift portion 12 has a rectangular shape with a curve having a radius of curvature R P at the corner portions, and the radius of curvature R T and the radius of curvature RP is R T ≧R P satisfies the relationship. The radius of curvature R T and the radius of curvature R P is R T >R P It is more preferable to satisfy the relationship. Also, the radius of curvature R T and the radius of curvature R P is R T ≧1.1×R P It is more preferable to satisfy the relationship, and R T ≧1.2×R P It is more preferable to satisfy the relationship.

[0022] The phase shift mask 10 has a curve with a radius of curvature R P at at least one of the four corners on the outer periphery of the phase shift portion 12. Among the four corners on the outer periphery of the light transmitting portion 11, at least the corner adjacent to the corner having the curve with the radius of curvature R P of the phase shift portion 12 has a curve with a radius of curvature R T , and R T and R P satisfy the above relationship (R T ≧R P , etc.). That is, for the corner having the curve with the radius of curvature R P on the outer periphery of the phase shift portion 12, the corner on the outer periphery of the light transmitting portion 11 adjacent to that corner has a curve with a radius of curvature R T , and R T and R P satisfy the above relationship (R T ≧R P , etc.). Thereby, the area of the phase shift portion 12 at that corner becomes wider, and the effect of the present invention can be obtained. On the other hand, for the corner having no curve on the outer periphery of the phase shift portion 12 (for example, a corner composed only of a straight line), the corner on the outer periphery of the light transmitting portion 11 adjacent to that corner may also be a corner having no curve, but it is preferable to be a corner having a curve. All of the four corners on the outer periphery of the light transmitting portion 11 have a curve with a radius of curvature R T , and at least one of the four corners on the outer periphery of the phase shift portion 12 has a curve with a radius of curvature R P , and the above relationship (RT ≧R P etc.) is preferably satisfied. Among the four corners of the outer periphery of the light-transmitting portion 11, when a plurality of corners have a curve with a radius of curvature R T , it is preferable that the radius of curvature R T of each corner is the same, but it is not limited thereto, and the radius of curvature R T of each corner may itself be different (for example, the radius of curvature R T of two corners on the outer periphery of the light-transmitting portion 11 may be different values of R T1 , R T2 ). The same applies to the radius of curvature R P of the corners on the outer periphery of the phase shift portion 12 (for example, the radius of curvature R P of two corners on the outer periphery of the phase shift portion 12 may be different values of R P1 , R P2 ). Further, when a plurality of corners among the four corners of the outer periphery of the light-transmitting portion 11 have a curve with a radius of curvature R T , and a plurality of corners among the four corners of the outer periphery of the phase shift portion 12 have a radius of curvature R P , in the case where adjacent corners have R T and R P satisfying the above relationship (R T ≧R P etc.), it is sufficient that the above relationship is satisfied at non-adjacent corners (for example, two corners on the outer periphery of the phase shift portion 12 have different values R P1 , R P2 of the radius of curvature R P , and two corners on the outer periphery of the light-transmitting portion 11 are corners having the radius of curvature R P1 , R P2 respectively adjacent to corners having different values R P , R T1 , R T2 of the radius of curvature R T , in the case where adjacent corners have R T1 ≧R P1 , R T2 ≧R P2 satisfied, and at non-adjacent corners, R T1 <R P2 , RT2 <R P1 may also be).

[0023] The outer peripheries of the light-transmitting part 11 and the phase shift part 12 are in a rectangular shape (rounded rectangular shape) each having a curve with a radius of curvature R T , R P at the four corners, and as the rectangular shape, it is more preferably a rounded rectangle or a rounded square having a curve with a radius of curvature R T at the four corners of a rectangle or a square. In addition, the rectangular shape in the present invention only needs to have four straight portions in the up-down, left-right directions in a plan view, and the ratio between the curved portion at the corner and the straight portion of the rectangular shape is not particularly limited. For example, a substantially circular shape or a substantially elliptical shape in which the curved portion at the corner is larger than the straight portion of the rectangular shape is also included in the rectangular shape in the present invention. These shapes can be confirmed using, for example, an optical microscope.

[0024] The size of the light-transmitting part 11 is not limited, but when a cross-shaped virtual line is drawn vertically and horizontally from the center-of-gravity position of the light-transmitting part 11 in a plan view, the distance (length) between two points where the outer periphery of the light-transmitting part 11 (the boundary between the light-transmitting part 11 and the phase shift part 12) intersects above and below the vertical virtual line, and the distance (length) between two points where the outer periphery of the light-transmitting part 11 (the boundary between the light-transmitting part 11 and the phase shift part 12) intersects on the left and right of the horizontal virtual line can be calculated as the average value. The width of the phase shift part 12 is not limited, but when a cross-shaped virtual line is drawn vertically and horizontally from the center-of-gravity position of the light-transmitting part 11 in a plan view, it can be calculated as the average value of the distance between the upper and lower straight portions in the vertical direction and the distance between the left and right straight portions in the horizontal direction of the phase shift part (the average value of the four widths in the up-down, left-right directions).

[0025] Radius of curvature R T , R PThe size is not limited, but in a plan view, perpendicular lines can be drawn between the portions deviating from the straight line portion, and based on the intersection point, the average value of each distance can be calculated as the radius of curvature. This will be described with reference to 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-transmitting 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-transmitting 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-transmitting 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-transmitting portion 11 (the straight line portion of the inner periphery of the phase shift portion 12). Thereby, it will 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-transmitting portion 11 is preferably 4 μm or less, more preferably 3 μm or less. Also, the size of the light-transmitting portion 11 is preferably 0.8 μm or more. Further, the radius of curvature R T of the light-transmitting portion 11 is the radius of curvature of the corner portion of the phase shift portion 12P in relation to (R T ≥ R P ), considering this, 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 performing exposure transfer of the transfer pattern on the substrate for a display device using a 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 on which the phase shift pattern is formed is formed first under the light-shielding film 3A) in which a light-shielding film 3A on which a light-shielding pattern is formed is formed on the phase shift film 2A. In the pre-attached type 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 on which the phase shift pattern is formed 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 the light-shielding pattern is formed and on the light-transmissive substrate 1. Note that 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] The phase shift section 12 is composed of a phase shift film 2, and it is preferable that the light transmissive section 11 has a configuration in which a part of the phase shift film 2 is removed in a hole shape to expose the light transmissive substrate 1. This phase shift film 2 is a phase shift film 2 (hereinafter, may be simply referred to as "phase shift film 2") on which a transfer pattern (phase shift pattern) including the light transmissive section 11 is formed.

[0032] The light transmissive substrate 1 is transparent to the exposure light. When assuming no surface reflection loss, the light transmissive substrate 1 has a transmittance of 85% or more, preferably 90% or more, with respect to the exposure light. The light transmissive 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 (such as SiO2-TiO2 glass). The main surface of the light transmissive substrate 1 (the surface on which the phase shift pattern etc. is provided) is a rectangular shape with a side length of 300 mm or more. In the case of a substrate with such a large main surface size, since it is difficult to increase the flatness of the main surface, a phase shift mask with a large DOF is preferable.

[0033] The pre-attached type phase shift film 2A can be made of a material containing a transition metal and silicon (Si). As the transition metal, molybdenum (Mo), tantalum (Ta), tungsten (W), titanium (Ti), zirconium (Zr), etc. are suitable, and titanium and molybdenum are more preferable. Also, the phase shift film 2A may 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 exemplified. The phase shift film 2A is preferably one that can be wet-etched. On the other hand, from the viewpoint of using a common wet etching solution for the post-attached type phase shift film 2B and the light shielding film 3B, it is preferable to use the above-mentioned chromium-based material, but it is not limited thereto, and it can also be made of a material containing a transition metal and silicon (Si).

[0034] In addition, in the case of a configuration in which an etching stopper film is interposed between the above-described phase shift film 2A and the light shielding film 3, it is preferable to use materials that can be patterned with the same wet etching solution for the materials of the phase shift film 2A and the light shielding film 3, and to use a material having etching selectivity between the materials of the phase shift film 2A and the light shielding film 3 for the material of the etching stopper film. For example, it is advisable to use a material 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] As the exposure light, for example, light having a wavelength range of 300 to 500 nm can be used. As the light source of the exposure apparatus for manufacturing a display device, for example, a light source (for example, a high-pressure mercury lamp) including any one or a plurality of i-line, h-line, and g-line can be preferably used. The representative wavelength of the exposure light can be any wavelength included in the above wavelength range. Further, when the miniaturization of the pattern progresses and it is desired to shift the center of gravity of the wavelength range of the exposure light to the short-wavelength side, light having a wavelength range shorter than the above wavelength range (for example, 250 to 400 nm) can also be used as the exposure light. For example, light in the short-wavelength side wavelength range including two or more of 313 nm, 334 nm, and 365 nm can be applied to the exposure light. Furthermore, light having a single wavelength of i-line (365 nm) can also be applied to the exposure light. Thus, it is preferable that the exposure light includes at least light having a wavelength of 365 nm. In this specification, unless otherwise specified, i-line (365 nm) is used as an example of the 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, as the NA of the optical system increases, the resolution improves. However, simply replacing the exposure apparatus used in the field of display device manufacturing with an apparatus having a larger NA is not necessarily advantageous either in terms of cost or technology. For example, changing the existing exposure apparatus to one with a higher NA means a huge investment for the display panel manufacturer. In addition, increasing the NA has drawbacks such as a decrease in the depth of focus (DOF). In the case of a phase shift mask for a display device, which has a larger area than a photomask for LSI manufacturing, it also leads to a decrease in production stability and yield. By setting the numerical aperture NA within the above-mentioned 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 P between the exposure light transmitted through the phase shift film 2 and the exposure light transmitted through air by the same distance as the film thickness of the phase shift film 2. P The phase difference Φ

[0038] The transmittance of the phase shift film 2 with respect to the exposure light satisfies the required value for the phase shift film 2. The transmittance T P of the phase shift film 2 is preferably 5% or more, and preferably 10% or more, with respect to the light of the representative wavelength included in the exposure light. On the other hand, the transmittance T P of the phase shift film 2 is preferably 50% or less, and more preferably 40% or less, with respect to the light of the representative wavelength included in the exposure light.

[0039] The film 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. Also, the film thickness of the phase shift film 2 is preferably 50 nm or more, more preferably 60 nm or more in order to ensure a desired transmittance.

[0040] The phase shift film 2 can be formed by a known film formation method such as a sputtering method. Also, the transfer pattern can be formed by a known method using wet etching or the like.

[0041] As shown in FIG. 4, in the case of the pre-attached type, the light shielding film 3A is disposed on the phase shift film 2A. On the other hand, as shown in FIG. 5, in the case of the post-attached type, the light shielding film 3B is disposed under 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 disposed above the phase shift film 2A. The light shielding film 3A is preferably made of a material having an etching selectivity different from that of the phase shift film 2A. On the other hand, in the case of the post-attached 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 can be formed, it is not necessary to have an etching selectivity between the phase shift film 2B and the light shielding film 3B.

[0042] The light-shielding film 3 (3A, 3B) is preferably composed of a chromium-based material containing chromium (Cr). The light-shielding film 3 is more preferably composed of a material containing chromium and substantially free of silicon. Substantially free of silicon means that the silicon content is less than 2%. More specifically, examples of the chromium-based material include a material composed of chromium (Cr) alone, or a material containing chromium (Cr) and at least one of oxygen (O), nitrogen (N), and carbon (C). Further, examples of the chromium-based material include a material containing chromium (Cr) and at least one of oxygen (O), nitrogen (N), and carbon (C), and further containing fluorine (F). For example, materials constituting 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 above-described phase shift film 2A and the light-shielding film 3, when a material containing a transition metal and silicon is used for the phase shift film 2A, it is preferable to also use a material containing a transition metal and silicon for the light-shielding film 3. In this case, a material containing chromium may be used for the etching stopper film.

[0043] The light-shielding film 3 can be formed by a known film-forming method such as a sputtering method.

[0044] The light-shielding film 3 has a function of blocking the transmission of exposure light. 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 the exposure light is preferably 2 or more, more preferably 3 or more, still more preferably 3.5 or more, and even more preferably 4 or more.

[0045] By having the above-described configuration, the phase shift mask 10 in the embodiment of the present invention can be an excellent phase shift mask that is advantageously adapted 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 Fig. 4, a mask blank having a phase shift film and a light-shielding film formed on a light-transmissive substrate is prepared. Regarding the specific configurations of the light-transmissive substrate, the phase shift film, and the light-shielding film formed on the mask blank, except for the points where the phase shift pattern and the light-shielding pattern are not formed, they are the same as the light-transmissive substrate 1, the phase shift film 2A, and the light-shielding film 3A formed on the phase shift mask 10.

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

[0048] Then, the resist film is peeled off once, a new resist film is formed on the light-shielding film, and by using the resist film pattern including the phase shift portions formed from the resist film as a mask and wet-etching the light-shielding film, a light-shielding film 3A having a light-shielding pattern is formed. In this way, the phase shift film 2A is exposed so as to surround the outer periphery of the light-transmissive portion 11 to form a phase shift portion 12, and a 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 time of each wet-etching and the shape of the pattern formed in the resist film, the radius of curvature R T and the radius of curvature R P are such that R T ≧R P is satisfied, and the corner portions of the outer periphery of the phase shift portion 12 and the corner portions of the outer periphery of the light-transmissive portion 11 can be formed. In this way, the phase shift mask 10 shown in Fig. 4 can be manufactured.

[0049] When manufacturing the phase shift mask 10 shown in FIG. 5, a mask blank having a light-shielding film formed on a light-transmissive substrate is prepared. The specific configurations of the light-transmissive substrate and the light-shielding film formed on the mask blank are the same as those of the light-transmissive substrate 1 and the light-shielding film 3B formed on the phase shift mask 10, except that no light-shielding pattern is 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 light-shielding film is wet-etched using a resist film pattern including the light-shielding pattern formed from the resist film as a mask, thereby forming a light-shielding film 3B having a light-shielding pattern.

[0051] Then, the resist film is peeled off once, and a phase shift film is formed on the light-shielding film 3B and the exposed light-transmissive substrate 1. A new resist film is formed on the phase shift film, and the phase shift film is wet-etched using a resist film pattern including 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 film 2B is exposed so as to surround the outer periphery of the light-transmissive portion 11 to form a phase shift portion 12, and a light-shielding portion 13 can be formed so as to surround the outer periphery of the phase shift portion 12. Also in this manufacturing method, by adjusting the time of each wet etching and the shape of the pattern formed on the resist film, the radius of curvature R T and the radius of curvature R P are such that R T ≧R P the corners of the outer periphery of the phase shift portion 12 and the corners of the outer periphery of the light-transmissive portion 11 can be formed so as to satisfy the relationship. In this way, the phase shift mask 10 shown in FIG. 5 can be manufactured.

[0052] <Manufacturing method of display device> A method for manufacturing a display device according to the present embodiment will be described. The method for manufacturing a display device according to the present embodiment includes a step of placing the phase shift mask described in the above-described embodiment on a mask stage of an exposure apparatus, and a step of 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. Hereinafter, each step will be described in detail.

[0053] In the placement step, 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 arranged so as to face a resist film formed on a substrate for a display device through a projection optical system of the exposure apparatus.

[0054] In the pattern transfer step, the phase shift mask is irradiated with exposure light 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 including light of a plurality of wavelengths selected from the wavelength range of 313 nm to 436 nm, or monochromatic light selected by cutting a certain wavelength range from the wavelength range of 313 nm to 436 nm with a filter or the like, or monochromatic light emitted from a light source having a wavelength range of 313 nm to 436 nm. For example, the exposure light is composite light including at least one of i-line, h-line, and g-line, or monochromatic light of i-line. By using composite light as the exposure light, the exposure light intensity can be increased and the throughput can be improved. Therefore, the manufacturing cost of the display device can be reduced. Note that 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 the present embodiment, a high-definition display device having high resolution and fine contact holes can be manufactured.

[0056] <Experimental Example> Regarding the phase shift mask of this embodiment, its transfer performance was compared and evaluated by optical simulation. That is, for a phase shift mask having a transfer pattern for forming a hole pattern with a diameter of 1.9 μm on a transfer object (for example, a resist film provided on a substrate for a display device), optical simulation was performed on what transfer performance would be shown when exposure conditions were set. As the exposure conditions, the numerical aperture NA was set to 0.11, and the wavelength of the exposure light was set to a single wavelength of i-line (wavelength 365 nm). Here, the phase difference of the phase shift portion was set to 180 degrees. The results of experimental examples for explaining the present invention will be described with reference to FIGS. 6 to 12. FIGS. 6 to 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 and the relationship between the difference and the change rate of the DOF. In FIGS. 6 to 12, the horizontal axis of the graph represents the difference (R T -R P ) [μm] between T and P , and the vertical axis of the graph represents the change rate of the DOF [%]. Therefore, in FIGS. 6 to 12, at the origin of the graph, the radius of curvature R of the light-transmitting portion T and the radius of curvature R of the phase shift portion P are equal, and the ratio of the vertical axis is calculated based on the value of the DOF [μm] at this time. In FIGS. 6 to 12, the region satisfying the relationship of R T ≥R P defined in the present invention is the right half region including the origin of the graph. Here, in any of the samples in FIGS. 6 to 12, the value of the DOF corresponding to the origin of the graph was within the allowable range. The change rate of the DOF [%] is the change rate of the DOF based on the DOF when R T =R P . That is, in the data of the same sample (under the condition of the same radius of curvature R p ) described later, when the difference (R T -R P ) is 0 (R T =R P ), the DOF is D B , and a specific difference (RT - RP) (where R T ≠RP ) In the case of, let the DOF be D TP When that is the case, the change rate D of the DOF in that specific difference (RT - RP) V is (D TP - D B ) / D B × 100 [%] and is calculated by the formula.

[0057] In the experimental example of FIG. 6, the transmittance of the phase shift portion 12 was set to 5%, the width of the phase shift portion 12 was set to 1.2 μm, and the size of the light transmitting portion 11 was set to 2.0 μm. Samples a1, a2, a3, and a4 in FIG. 6 are those in which the radius of curvature R P of the phase shift portion 12 was set to 0.4 μm, 0.6 μm, 0.8 μm, and 1.0 μm, respectively. Then, for each of the samples a1 to a4, the radius of curvature R T of the light transmitting portion 11 was set to 0.4 μm, 0.6 μm, 0.8 μm, and 1.0 μm, respectively, and the difference (R T - R P ) [μm] between R T and R P was calculated, and the change rate [%] of each DOF was calculated. As shown in FIG. 6, in any of the samples a1 to a4, when the difference between R T and R P is 0 or more, the DOF change rate increases, and it was found that the resolution can be improved. On the other hand, in any of the samples a1 to a4, when the difference between R T and R P is less than 0, the DOF change rate decreases, and it was found that there is a possibility of hindering the resolution.

[0058] In the experimental example of FIG. 7, the transmittance of the phase shift portion 12 was set to 10%, the width of the phase shift portion 12 was set to 1.2 μm, and the size of the light transmitting portion 11 was set to 2.0 μm. Samples b1, b2, b3, and b4 in FIG. 7 are those in which the radius of curvature R P of the phase shift portion 12 was set to 0.4 μm, 0.6 μm, 0.8 μm, and 1.0 μm, respectively. And for each of the samples b1 to b4, the radius of curvature R of the light-transmitting portion 11 T was set to 0.4 μm, 0.6 μm, 0.8 μm, and 1.0 μm, respectively, and the difference (R T -R P ) [μm] between R T and R P was calculated, and the change rate [%] of each DOF was calculated. As shown in FIG. 7, in any of the samples b1 to b4, when the difference between R T and R P is 0 or more, the DOF change rate increases, and it was found that the resolution can be improved. On the other hand, in any of the samples b1 to b4, when the difference between R T and R P is less than 0, the DOF change rate decreases, and it was found that there is a possibility of hindering the resolution.

[0059] In the experimental example of FIG. 8, the transmittance of the phase shift portion 12 was set to 20%, the width of the phase shift portion 12 was set to 1.2 μm, and the size of the light-transmitting portion 11 was set to 2.0 μm. Samples c1, c2, c3, and c4 in FIG. 8 are those in which the radius of curvature R P of the phase shift portion 12 was set to 0.4 μm, 0.6 μm, 0.8 μm, and 1.0 μm, respectively. And for each of the samples c1 to c4, the radius of curvature R T of the light-transmitting portion 11 was set to 0.4 μm, 0.6 μm, 0.8 μm, and 1.0 μm, respectively, and the difference (R T -R P ) [μm] between R T and R P was calculated, and the change rate [%] of each DOF was calculated. As shown in FIG. 8, in any of the samples c1 to c4, when the difference between R T and R P is 0 or more, the DOF change rate increases, and it was found that the resolution can be improved. On the other hand, in any of the samples c1 to c4, when the difference between R T and R PWhen the difference is less than 0, it has been found that the DOF change rate decreases, which may cause problems in resolution.

[0060] In the experimental example of FIG. 9, the transmittance of the phase shift portion 12 was set to 10%, the width of the phase shift portion 12 was set to 1.2 μm, and the size of the light transmitting portion 11 was set to 2.2 μm. Samples d1, d2, d3, and d4 in FIG. 9 are those in which the radius of curvature R P of the phase shift portion 12 was set to 0.4 μm, 0.6 μm, 0.8 μm, and 1.0 μm, respectively. Then, for each of the samples d1 to d4, the radius of curvature R T of the light transmitting portion 11 was set to 0.4 μm, 0.6 μm, 0.8 μm, and 1.0 μm, respectively, and the difference (R T -R P ) [μm] between R T and R P was calculated, and the change rate [%] of each DOF was calculated. As shown in FIG. 9, in any of the samples d1 to d4, when the difference between R T and R P is 0 or more, it has been found that the DOF change rate increases and the resolution can be improved. On the other hand, in any of the samples d1 to d4, when the difference between R T and R P is less than 0, it has been found that the DOF change rate decreases, which may cause problems in resolution.

[0061] In the experimental example of FIG. 10, the transmittance of the phase shift portion 12 was set to 10%, the width of the phase shift portion 12 was set to 1.2 μm, and the size of the light transmitting portion 11 was set to 2.4 μm. Samples e1, e2, e3, and e4 in FIG. 10 are those in which the radius of curvature R P of the phase shift portion 12 was set to 0.4 μm, 0.6 μm, 0.8 μm, and 1.0 μm, respectively. Then, for each of the samples e1 to e4, the radius of curvature R T of the light transmitting portion 11 was set to 0.4 μm, 0.6 μm, 0.8 μm, and 1.0 μm, respectively, and the difference (R T -R P ) between RT -R P ) [μm] and the rate of change [%] of each DOF was also calculated. As shown in FIG. 10, in all samples e1 to e4, R T and R P It was found that when the difference between R and R is 0 or more, the DOF change rate increases and the resolution can be improved. T and R P It has been found that when the difference is less than 0, the DOF change rate decreases, which may cause a problem in resolution.

[0062] 11, the transmittance of the phase shift portion 12 was set to 10%, the width of the phase shift portion 12 was set to 0.8 μm, and the size of the light transmitting portion 11 was set to 2.0 μm. P are set to 0.4 μm, 0.6 μm, 0.8 μm, and 1.0 μm, respectively. Then, for each of the samples f1 to f4, the radius of curvature R of the light-transmitting portion 11 T are set to 0.4 μm, 0.6 μm, 0.8 μm, and 1.0 μm, respectively, and R T and R P The difference (R T -R P ) [μm] and the rate of change [%] of each DOF was also calculated. As shown in FIG. 11, in all of the samples f1 to f4, R T and R P It was found that when the difference between R and R is 0 or more, the DOF change rate increases and the resolution can be improved. T and R P It has been found that when the difference is less than 0, the DOF change rate decreases, which may cause a problem in resolution.

[0063] In the experimental example of FIG. 12, the transmittance of the phase shift portion 12 was set to 10%, the width of the phase shift portion 12 was set to 1.0 μm, and the size of the light transmissive portion 11 was set to 2.0 μm. Samples g1, g2, g3, and g4 in FIG. 12 have a radius of curvature R of the phase shift portion 12 P set to 0.4 μm, 0.6 μm, 0.8 μm, and 1.0 μm, respectively. Then, for each of the samples g1 to g4, the radius of curvature R of the light transmissive portion 11 T was set to 0.4 μm, 0.6 μm, 0.8 μm, and 1.0 μm, respectively, and the difference (R T -R P ) [μm] between R T and R P was calculated, and the change rate [%] of each DOF was calculated. As shown in FIG. 12, in any of the samples g1 to g4, when the difference between R T and R P is 0 or more, the change rate of DOF increases, and it was found that the resolution can be improved. On the other hand, in any of the samples g1 to g4, when the difference between R T and R P is less than 0, the change rate of DOF decreases, and it was found that there is a possibility of hindering the resolution.

[0064] On the other hand, optical simulation was 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 of FIG. 13, it is the result of performing optical simulation under the same conditions (the transmittance of the phase shift portion 12 is 10%, the width of the phase shift portion 12 is 1.2 μm, and the size of the light transmissive portion 11 is 2.0 μm) as in the experimental example of FIG. 7, except that the numerical aperture NA is changed to 0.08. Samples h1, h2, h3, and h4 in FIG. 13 have a radius of curvature R of the phase shift portion 12 P set to 0.4 μm, 0.6 μm, 0.8 μm, and 1.0 μm, respectively. Then, for each of the samples h1 to h4, the radius of curvature R of the light transmissive portion 11 T was set to 0.4 μm, 0.6 μm, 0.8 μm, and 1.0 μm, respectively, and for R Tand R P The difference (R T - R P ) [μm] was calculated, and the change rate [%] of each DOF was calculated. As shown in FIG. 13, in any of the samples h1 to h4, when the difference between R T and R P is 0 or more, the DOF change rate increases, and it was found that the resolution can be improved. On the other hand, in any of the samples h1 to h4, when the difference between R T and R P is less than 0, the DOF change rate decreases, and it was found that there is a possibility of hindering the resolution.

[0065] In the experimental example of FIG. 14, it is the result of performing optical simulation under the same conditions (the transmittance of the phase shift portion 12 is 10%, the width of the phase shift portion 12 is 1.2 μm, and the size of the light transmitting portion 11 is 2.0 μm) except that the numerical aperture NA is changed to 0.12 compared with the experimental example of FIG. 7. Samples i1, i2, i3, and i4 in FIG. 14 are those in which the radius of curvature R P of the phase shift portion 12 is 0.4 μm, 0.6 μm, 0.8 μm, and 1.0 μm, respectively. Then, for each of the samples i1 to i4, the radius of curvature R T of the light transmitting portion 11 is 0.4 μm, 0.6 μm, 0.8 μm, and 1.0 μm, respectively, and the difference (R T and R P difference (R T - R P ) [μm] was calculated, and the change rate [%] of each DOF was calculated. As shown in FIG. 13, in any of the samples i1 to i4, when the difference between R T and R P is 0 or more, the DOF change rate increases, and it was found that the resolution can be improved. On the other hand, in any of the samples h1 to h4, when the difference between R T and R P is less than 0, the DOF change rate decreases, and it was found that there is a possibility of hindering the resolution.

[0066] Also, in the case of the experimental examples of FIGS. 6 and 8 to 12, optical simulations were respectively performed by changing the numerical aperture NA to 0.08 and 0.12. In any of the simulation results, similar to other experimental examples, when the difference between R T and R P is 0 or more, the DOF change rate increases and the resolution can be improved. When the difference between R T and R P is less than 0, it was found that the DOF change rate decreases and there is a possibility of hindering the resolution.

[0067] Furthermore, optical simulations were also respectively performed for the cases where the wavelength of the exposure light was set to a shorter wavelength (334 nm) and a longer wavelength (405 nm). In any of the simulation results, similar to other experimental examples, when the difference between R T and R P is 0 or more, the DOF change rate increases and the resolution can be improved. When the difference between R T and R P is less than 0, it was found that the DOF change rate decreases and there is a possibility of hindering the resolution.

Explanation of Signs

[0068] 1 Transparent substrate 2 (2A, 2B) Phase shift film (phase shift pattern) 3 (3A, 3B) Light-shielding film (light-shielding pattern) 10 Phase shift mask 11 Transmissive part 12 Phase shift part 13 Light-shielding part

Claims

1. A phase shift mask provided with a light-transmitting portion, a phase shift portion, and a light-shielding portion on a light-transmissive substrate, wherein the light-transmitting portion is formed by exposing the light-transmissive substrate in a hole shape, 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 periphery of the phase shift portion, The outer periphery of the light-transmitting portion has a rectangular shape with a curve having a radius of curvature R at at least one corner Ｔ and The outer periphery of the phase shift part has the curvature radius R Ｔ and is a rectangular shape having at least a curve with a curvature radius R at a corner adjacent to the corner having the curve with the curvature radius R Ｐ as described above. The radius of curvature R Ｔ and the radius of curvature R Ｐ are such that R Ｔ ≧ R Ｐ satisfies the relationship and the phase shift mask is characterized by the above.

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 by the above.

3. The transmittance of the phase shift portion with respect to the exposure light is 5% or more, and the phase difference generated 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. The phase shift mask according to claim 1 or 2, characterized by the above.

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

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

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

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

8. The phase shift portion is made of a phase shift film, and the light-transmitting portion is formed by removing a part of the phase shift film in a hole shape to expose the light-transmissive substrate. The phase shift mask according to claim 1 or 2, characterized by the above.

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

10. A step of placing the phase shift mask according to claim 1 or 2 on a mask stage of an exposure apparatus; and a step of 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 display device, characterized by the above.

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