Photomask and method for manufacturing the same

Abstract

To provide a photomask that can embody a fine pattern in manufacturing a display device or the like, and can reduce a failure of a display device, and a method for manufacturing the photomask.SOLUTION: A photomask includes: a transparent substrate including a phase inversion region and a light shielding region adjacent to the phase inversion region; a phase inversion film which is arranged in the phase inversion region and the light shielding region on the transparent substrate, and in which a 1-1 opening exposing a top face of the transparent substrate is defined in the phase inversion region and a 1-2 opening exposing the top face of the transparent substrate is defined in the light shielding region; and an etching stopping film which is arranged in the phase inversion region and the light shielding region on the phase inversion film, and in which a 2-1 opening exposing the 1-1 opening and a 2-2 opening exposing the 1-2 opening are defined.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a photomask and a method for manufacturing the same, and more particularly to a photomask used in an exposure process and a method for manufacturing the same. [Background technology]

[0002] Semiconductor devices or display devices are manufactured by a photolithography process. The photolithography process determines the critical dimension of semiconductor elements and includes the steps of applying a photoresist, exposing it to light, and developing it. The exposure process transfers a photomask pattern provided on a photomask substrate to the photoresist on a wafer.

[0003] Recently, photomasks including phase shifting films have been manufactured to realize fine patterns on semiconductor devices or display devices, and the transmittance and degree of phase shift of light incident on the photomask vary depending on the thickness of the phase shifting film. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6324756 (JP6324756B; KR2020-0084084A) Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a photomask that reduces defects in display devices.

[0006] Another object of the present invention is to provide a method for manufacturing the photomask.

[0007] However, the object of the present invention is not limited to the above-mentioned object, and can be expanded in various ways without departing from the spirit and scope of the present invention. [Means for solving the problem]

[0008] In order to achieve the object of the present invention, one embodiment of the photomask is characterized by comprising: a transparent substrate including a phase shift region and a light-shielding region adjacent to the phase shift region; a phase shift film disposed in the phase shift region and the light-shielding region on the transparent substrate, and having a 1-1 opening that exposes the top surface of the transparent substrate in the phase shift region and a 1-2 opening that exposes the top surface of the transparent substrate in the light-shielding region; and an etching stop film disposed in the phase shift region and the light-shielding region on the phase shift film, and having a 2-1 opening that exposes the 1-1 opening and a 2-2 opening that exposes the 1-2 opening.

[0009] The thickness of the etch stop layer is 450 Å or more.

[0010] The light transmittance of the phase shift film is 3.0% or more and 50% or less.

[0011] The product of the light transmittance of the phase shift film and the light transmittance of the etching stop film is 0.10% or less.

[0012] The light transmittance of the transport reversal film is greater than the light transmittance of the etch stop film.

[0013] The size of the first-2 opening is substantially the same as the size of the second-2 opening.

[0014] In the phase shift region, the size of the 1-1 opening is smaller than the size of the 2-1 opening.

[0015] The photomask further includes a light-shielding film disposed on the etching stop film and overlapping the phase shift region.

[0016] A third opening is defined in the light shielding curtain to expose the second-first opening.

[0017] The size of the third opening is substantially the same as the size of the second-first opening.

[0018] In order to achieve another object of the present invention, a method for manufacturing a photomask according to the present invention includes the steps of: forming a preliminary phase shift film on a transparent substrate including a phase shift region and a light-shielding region adjacent to the phase shift region, the preliminary phase shift film overlapping the phase shift region and the light-shielding region; forming a preliminary etching stop film on the preliminary phase shift film overlapping the phase shift region and the light-shielding region; forming a preliminary light-shielding film on the preliminary etching stop film overlapping the phase shift region and the light-shielding region; removing a portion of the preliminary phase shift film to form a phase shift film defining a 1-1 opening exposing the top surface of the transparent substrate in the phase shift region and a 1-2 opening exposing the top surface of the transparent substrate in the light-shielding region; and removing at least a portion of the preliminary light-shielding film and a portion of the preliminary etching stop film to form an etching stop film defining a 2-1 opening exposing the 1-1 opening and a 2-2 opening exposing the 1-2 opening.

[0019] The step of forming the etch stop layer is performed before the step of forming the transfer reversal layer.

[0020] The step of forming the etching stop film includes the steps of forming a first photoresist layer on the preliminary light-shielding film, removing a portion of the first photoresist layer to form a first photoresist pattern, removing a portion of each of the preliminary etching stop film and the preliminary light-shielding film using the first photoresist pattern, forming the second-first opening and the second-second opening that penetrate the preliminary etching stop film in a thickness direction and expose a portion of the upper surface of the preliminary phase shift film, and forming a third opening that penetrates the preliminary light-shielding film in a thickness direction and exposes the second-first opening.

[0021] The step of forming the phase shift film includes the steps of forming a second photoresist layer on the etching stop film overlapping the phase shift region to fill the second-1 opening, removing a portion of the second photoresist layer to form a second photoresist pattern, removing a portion of the preliminary phase shift film using the second photoresist pattern to form the first-1 opening that penetrates the phase shift film in the thickness direction and exposes the top surface of the transparent substrate, and forming the first-2 opening that penetrates the phase shift film in the thickness direction and exposes the top surface of the transparent substrate.

[0022] The steps of forming the 1-1 opening and forming the 1-2 opening are performed simultaneously.

[0023] After forming the second photoresist pattern, the portion of the preliminary light-shielding film overlapping the light-shielding region is removed.

[0024] After forming the second photoresist pattern, the preliminary light-shielding film overlapping the phase shift region and the light-shielding region is removed.

[0025] The second photoresist layer is not formed in the light-shielding area.

[0026] The size of the first-2 opening is substantially the same as the size of the second-2 opening.

[0027] The size of the 1-1 opening is smaller than the size of the 2-1 opening. [Effects of the Invention]

[0028] The photomask according to the present invention includes a transparent substrate including a phase shift region and a light-shielding region, a phase shift film disposed on the transparent substrate, and an etching stop film disposed on the phase shift film. In the phase shift region, the size of a first opening defined in the phase shift film is smaller than the size of a second opening defined in the etching stop film. In the light-shielding region, the size of a first opening defined in the phase shift film and the size of a second opening defined in the etching stop film are substantially the same. This inverts the phase of light incident on the phase shift region and simultaneously blocks the light incident on the light-shielding region, thereby further simplifying the manufacturing process of a display device using a photomask.

[0029] In addition, the thickness of the etch stop layer can be adjusted to reduce the transmittance of light passing through the etch stop layer and the phase shift layer, thereby increasing the resolution of the photomask since light can be blocked in the light-shielding region even when a phase shift layer with high light transmittance is used.

[0030] In the method for manufacturing a photomask according to the present invention, a preliminary light-shielding film overlapping the light-shielding region is removed. As a result, the size of the first-2 opening and the size of the second-2 opening defined in the photomask manufactured through two exposure processes for forming first and second photoresist patterns are substantially the same. As a result, light incident on the light-shielding region (LBA) and passing through the phase shift film (PSM) also passes through the etching stop film (ESM), preventing the phase of the light from being inverted in the light-shielding region (LBA).

[0031] However, the effects of the present invention are not limited to the above effects, and can be expanded in various ways without departing from the spirit and scope of the present invention. [Brief explanation of the drawings]

[0032] [Figure 1]FIG. 1 is a perspective view showing a photomask according to one embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view for explaining the manufacture of a display device using the photomask of FIG. [Figure 3] FIG. 3 is a cross-sectional view showing an example of a cross section taken along line II' in FIG. [Figure 4] FIG. 4 is an enlarged plan view showing an example of the first pattern in FIG. [Figure 5] FIG. 5 is an enlarged plan view of the second pattern of FIG. [Figure 6] 6A to 6C are cross-sectional views showing a method for manufacturing the photomask in FIG. [Figure 7] 7A to 7C are cross-sectional views showing a method for manufacturing the photomask in FIG. [Figure 8] 8A to 8C are cross-sectional views showing a method for manufacturing the photomask in FIG. [Figure 9] 9A to 9C are cross-sectional views showing a method for manufacturing the photomask in FIG. [Figure 10] 10A to 10C are cross-sectional views showing a method for manufacturing the photomask in FIG. [Figure 11] FIG. 11 is a cross-sectional view showing a method for manufacturing the photomask in FIG. [Figure 12] 12A to 12C are cross-sectional views showing a method for manufacturing the photomask in FIG. [Figure 13] FIG. 13 is a cross-sectional view showing another example of a cross section taken along line II' in FIG. [Figure 14] FIG. 14 is an enlarged plan view showing another example of the first pattern in FIG. [Figure 15] 15A to 15C are cross-sectional views showing a method for manufacturing the photomask in FIG. [Figure 16] 16A to 16C are cross-sectional views showing a method for manufacturing the photomask in FIG. [Figure 17] 17A to 17C are cross-sectional views showing a method for manufacturing the photomask in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0033] Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. The same reference numerals will be used to refer to the same elements in the drawings, and redundant descriptions of the same elements will be omitted.

[0034] Fig. 1 is a perspective view showing a photomask according to one embodiment of the present invention. Fig. 2 is a perspective view for explaining the manufacture of a display device using the photomask of Fig. 1. Fig. 3 is a cross-sectional view showing an example of a cross section taken along line II' of Fig. 1.

[0035] As shown in FIGS. 1 to 3, a photomask (PM) according to one embodiment of the present invention is a mask used in manufacturing a display device (DD). For example, the photomask (PM) is an exposure mask used in an exposure process of the display device (DD). Specifically, the photomask (PM) is a mask used in the process of forming a specific pattern in a portion of the display device (DD) (e.g., an insulating layer, a metal layer, etc.). However, in the embodiment of the present invention, the use of the photomask (PM) is not limited to the manufacture of a display device (DD), and it can be used in the manufacture of various electronic devices.

[0036] In this specification, a plane is defined by a first direction (DR1) and a second direction (DR2) that intersects with the first direction (DR1). For example, the second direction (DR2) is perpendicular to the first direction (DR1). Also, a third direction (DR3) is perpendicular to the plane.

[0037] The photomask (PM) includes a phase shift area (PSA) and a light blocking area (LBA). The phase shift area (PSA) includes a first pattern (P1) corresponding to the position of the specific pattern. A plurality of first patterns (P1) are arranged in a first direction (DR1) or a second direction (DR2).

[0038] The light blocking area (LBA) is adjacent to the phase shifting area (PSA). For example, the light blocking area (LBA) surrounds the phase shifting area (PSA). The light blocking area (LBA) includes a second pattern (P2) corresponding to the position of the specific pattern. A plurality of second patterns (P2) are arranged in the first direction (DR1) or the second direction (DR2).

[0039] When manufacturing a display device (DD), the phase shifting area (PSA) corresponds to the display area (DA) of the display device (DD). Specifically, the position of the first pattern (P1) of the phase shifting area (PSA) corresponds to the position of a specific portion of the pixels (PX) included in the display area (DA).

[0040] The peripheral area (PA) is adjacent to the display area (DA). When manufacturing a display device (DD), the light-shielding area (LBA) corresponds to the peripheral area (PA) of the display device (DD). Specifically, the position of the second pattern (P2) in the light-shielding area (LBA) corresponds to the position of a specific part of a component (e.g., a driver, a power wiring, etc.) arranged in the peripheral area (PA).

[0041] The photomask (PM) includes a transparent substrate (TS), a phase shifting film (PSM), an etch stop film (ESM), and a light-shielding film (LBM). Since the transparent substrate (TS) includes a phase shifting area (PSA) and a light-shielding area (LBA), the photomask (PM) also includes a phase shifting area (PSA) and a light-shielding area (LBA).

[0042] The transparent substrate (TS) is a transparent substrate that can transmit light. For example, the transparent substrate (TS) includes quartz glass. This allows ultraviolet light to easily pass through the transparent substrate (TS). As shown in FIG. 1, the transparent substrate (TS) has a rectangular parallelepiped shape. However, the shape of the transparent substrate (TS) is not limited thereto, and the transparent substrate (TS) can have various shapes.

[0043] The phase shifting film (PSM) is disposed on the transparent substrate (TS), for example, the phase shifting film (PSM) overlaps a portion of the transparent substrate (TS).

[0044] The phase shift film (PSM) has a first opening (OP1) defined therein, exposing the top surface of the transparent substrate (TS). The first opening (OP1) includes a first opening (OP1-1) located in the phase shift area (PSA) and a second opening (OP1-2) located in the light blocking area (LBA). The first opening (OP1-1) and the second opening (OP1-2) have substantially the same size. However, in an embodiment of the present invention, the sizes of the first opening (OP1-1) and the second opening (OP1-2) are not limited thereto, and the sizes of the first opening (OP1-1) and the second opening (OP1-2) may be different from each other.

[0045] A phase shifter (PSM) inverts the phase of light transmitted through the PSM. Specifically, when light is incident in a third direction (DR3) and transmits through a transparent substrate (TS) and a phase shifter (PSM), the phase of the transmitted light is opposite to the phase of the incident light. As a result, the light transmitted through the transparent substrate (TS) and the phase shifter (PSM) has a relatively larger NILS (Normalized Image Log-Slope) value than light transmitted through other components of the photomask (PM) (e.g., an etch stop layer (ESM), a light-blocking layer (LBM), etc.). This improves the resolution of the photomask (PM).

[0046] The light transmittance of the phase shift film (PSM) is lower than that of the transparent substrate (TS). In one embodiment, the light transmittance of the phase shift film (PSM) is 3.0% or more and 50% or less. The light transmittance of the transparent substrate (TS) is 80% or more. However, in the present invention, the light transmittance of the transparent substrate (TS) and the phase shift film (PSM) is not limited thereto. In one embodiment, the phase shift film (PSM) includes chromium (Cr), chromium oxide (CrOx), chromium nitride (CrNx), etc. These can be used alone or in combination.

[0047] The etch stop layer (ESM) is a layer that prevents a portion of the phase shift layer (PSM) from being etched during the photomask (PM) manufacturing process, which will be described later with reference to FIG. 9 regarding the photomask (PM) manufacturing method.

[0048] In one embodiment, the etch stop layer (ESM) comprises molybdenum (Mo), silicon (Si), zirconium (Zr), silicon (Si), etc., which may be used alone or in combination.

[0049] In one embodiment, the thickness of the ESM is between 450 Å and 1500 Å. Preferably, the thickness of the ESM is between 472 Å and 502 Å. When the thickness of the ESM is less than 450 Å, the transmittance of light passing through the ESM and the phase shifter increases, and the blocking of light incident on the light blocking area (LBA) decreases. In addition, the process of manufacturing a photomask (PM) including an ESM with a thickness greater than 1500 Å requires relatively more manufacturing time and cost than the process of manufacturing a photomask (PM) including an ESM with a thickness less than 1500 Å.

[0050] The light transmittance of an ESM varies depending on the thickness of the ESM. Specifically, the thicker the ESM, the lower the light transmittance through the ESM. Therefore, the light transmittance of an ESM is between 0.02% and 3.32%. Preferably, the light transmittance of an ESM is between 0.02% and 1.90%.

[0051] The optical transmittance of the phase shift film (PSM) is adjusted by the optical transmittance of the etching stop film (ESM). In one embodiment, the product of the optical transmittance of the phase shift film (PSM) and the optical transmittance of the etching stop film (ESM) is 0.10% or less. That is, the optical density of the double film consisting of the phase shift film (PSM) and the etching stop film (ESM) is 3.0 or more. Preferably, the product of the optical transmittance of the phase shift film (PSM) and the optical transmittance of the etching stop film (ESM) is 0.0010% or more and 0.10% or less. That is, the optical density of the double film consisting of the phase shift film (PSM) and the etching stop film (ESM) is 3.0 or more and 5.0 or less. This allows the etching stop film (ESM) to block light that has passed through the transparent substrate (TS) and the phase shift film (PSM) and reached the etching stop film (ESM). That is, the photomask (PM) can partially block light through the overlapping areas of the phase shifter (PSM) and etch stopper (ESM).

[0052] In one embodiment, the optical transmittance of the phase shifter (PSM) is greater than that of the etching stop layer (ESM). For example, if the optical transmittance of the phase shifter (PSM) is 50.0%, the optical transmittance of the etching stop layer (ESM) is 0.2%. In such a case, the thickness of the phase shifter (PSM) is 486 Å. However, the present invention is not limited thereto, and the optical transmittance of the phase shifter (PSM) may be less than that of the etching stop layer (ESM). For example, the optical transmittance of the phase shifter (PSM) is 3.0%, and the optical transmittance of the etching stop layer (ESM) is 3.32%. In such a case, the thickness of the phase shifter (PSM) is 450 Å.

[0053] The phase shift film (PSM) has second openings (OP2) defined therein, including a second opening (OP2-1) located in the phase shift area (PSA) and a second opening (OP2-2) located in the light blocking area (LBA).

[0054] The 2-1 opening (OP2-1) exposes the 1-1 opening (OP1-1) and the upper surface of the phase shift film (PSM). That is, the size of the 2-1 opening (OP2-1) is larger than the size of the 1-1 opening (OP1-1). As a result, when light incident on the phase shift area (PSA) passes through the phase shift film (PSM) exposed by the 2-1 opening (OP2-1), the phase of the light is inverted.

[0055] The second-second opening (OP2-2) exposes the first-second opening (OP1-2). In one embodiment, the size of the second-second opening (OP2-2) is substantially the same as the size of the first-second opening (OP1-2). This allows any light transmitted through the phase shifter (PSM) in the light blocking area (LBA) to reach the etching stop layer (ESM).

[0056] The light-shielding layer (LBM) is disposed on the etch-stop layer (ESM). The light-shielding layer (LBM) is located in the phase shift area (PSA). For example, the light-shielding layer (LBM) overlaps the etch-stop layer (ESM) in the phase shift area (PSA). In other words, the light-shielding layer (LBM) is not located in the light-shielding area (LBA).

[0057] The light-shielding film (LBM) blocks light that passes through the transparent substrate (TS), phase shift film (PSM), and etching stop film (ESM) and reaches the light-shielding film (LBM). In other words, the photomask (PM) can partially block light through the areas where the light-shielding film (LBM) is arranged.

[0058] In one embodiment, the light-blocking film (LBM) comprises a light-blocking material, for example, chromium.

[0059] The light-shielding film (LBM) is defined with a first-first opening (OP1-1), a second-first opening (OP2-1), and a third opening (OP3) that exposes a portion of the top surface of the phase shift film (PSM). The size of the third opening (OP3) is substantially the same as the size of the second-first opening (OP2-1). This allows all light that has passed through the phase shift film (PSM) in the phase shift area (PSA) to reach the light-shielding film (LBM). However, in the present invention, the size of the third opening (OP3) is not limited to this, and the size of the third opening (OP3) may be larger than the size of the second-first opening (OP2-1).

[0060] The transparent substrate (TS), phase shifting film (PSM), etching stop film (ESM), and light-shielding film (LBM) located in the phase shifting area (PSA) form a first pattern (P1), and the transparent substrate (TS), phase shifting film (PSM), and etching stop film (ESM) located in the light-shielding area (LBA) form a second pattern (P2).

[0061] When performing an exposure process using a photomask (PM), light incident on the photomask (PM) is incident in a third direction (DR3). Specifically, the light is irradiated toward the back surface of the transparent substrate (TS). The light passes through the transparent substrate (TS), phase shift film (PSM), and etching stop film (ESM) in order, and is incident on the display area (DA) and peripheral area (PA). Furthermore, if the light is incident on the light-shielding film (LBM), the light is not incident on the display device (DD). That is, the fewer the number of light-transmitting components of the photomask (PM) (e.g., transparent substrate (TS), phase shift film (PSM), and etching stop film (ESM)) and the higher the transmittance of the transmitting components, the greater the intensity of the light incident on the display device (DD).

[0062] The light used in the exposure process includes i-line light with a wavelength of 365 nm, g-line light with a wavelength of 436 nm, ultraviolet (UV) light with a wavelength of 248 nm, deep ultraviolet (DUV) light with a wavelength of 193 nm, etc. However, in the present invention, the type of light is not limited to these and may be light having various wavelength ranges.

[0063] As described above, the light-shielding area (LBA) is provided with a phase shifting film (PSM) and an etching stop film (ESM). In the phase shifting area (PSA), the size of the first-1 opening (OP1-1) is smaller than the size of the second-1 opening (OP2-1). In addition, in the light-shielding area (LBA), the sizes of the first-2 opening (OP1-2) and the second-2 opening (OP2-2) are substantially the same. This allows the phase of light incident on the phase shifting area (PSA) to be inverted and simultaneously the light incident on the light-shielding area (LBA) to be blocked, further simplifying the manufacturing process of a display device using a photomask (PM).

[0064] In addition, the thickness of the ESM is adjusted to reduce the transmittance of light that passes through both the ESM and PSM. This allows the light to be blocked by the light blocking area (LBA) even when a PSM with high light transmittance is used, thereby increasing the resolution of the photomask (PM).

[0065] Fig. 4 is an enlarged plan view showing an example of the first pattern in Fig. 2. Fig. 5 is an enlarged plan view showing the second pattern in Fig. 2. For example, Fig. 4 is a plan view of the first pattern (P1) viewed from the opposite direction to the third direction (DR3) in which light passes. Fig. 5 is a plan view of the second pattern (P2) viewed from the opposite direction to the third direction (DR3) in which light passes.

[0066] 4 and 5, in the first pattern (P1), the phase shift film (PSM) overlaps a portion of the transparent substrate (TS). Also, in the first pattern (P1), the 1-1 opening (OP1-1) exposes the top surface of the transparent substrate (TS). Therefore, during the exposure process in which light is incident in the direction opposite to the third direction (DR3), the light incident on the region within the 1-1 opening (OP1-1) in the first pattern (P1) can pass through only the transparent substrate (TS) in the photomask (e.g., the photomask (PM) in FIG. 1).

[0067] In one embodiment, the planar shape of the 1-1 opening (OP1-1) is a rectangle. That is, the shape of the upper surface of the transparent substrate (TS) exposed through the 1-1 opening (OP1-1) has a rectangle in plan. However, the present invention is not limited thereto, and the planar shape of the 1-1 opening (OP1-1) may have various shapes, such as a polygonal shape or a circular shape.

[0068] In the first pattern (P1), the light-shielding film (LBM) overlaps with a portion of the phase shifting film (PSM) and the transparent substrate (TS). Also, in the first pattern (P1), the second-first opening (OP2-1) and the third opening (OP3) expose the top surface of the phase shifting film (PSM). An etching stopper film (ESM) is disposed below the light-shielding film (LBM), but because the second-first opening (OP2-1) and the third opening (OP3) are the same size, only a portion of the top surface of the phase shifting film (PSM) is exposed through the second-first opening (OP2-1) and the third opening (OP3) in the first pattern (P1). As a result, during the exposure process, light incident on the region of the first pattern (P1) located between the boundary of the 1-1 opening (OP1-1) and the boundaries of the 2-1 opening (OP2-1) and the 3rd opening (OP3) can be transmitted only by the phase shift film (PSM) of the photomask configuration, while light incident on the region of the first pattern (P1) located outside the 2-1 opening (OP2-1) and the 3rd opening (OP3) is blocked by the phase shift film (PSM) and the light-shielding film (LBM) of the photomask configuration.

[0069] In one embodiment, the planar shape of each of the opening 2-1 (OP2-1) and the third opening (OP3) is a rectangle. That is, the shape of a portion of the upper surface of the phase shifter (PSM) exposed through the opening 2-1 (OP2-1) and the third opening (OP3) is a rectangle in plan. However, the present invention is not limited thereto, and the planar shape of each of the opening 2-1 (OP2-1) and the third opening (OP3) may be various shapes, such as a polygon or a circle.

[0070] In the second pattern (P2), the etching stopper film (ESM) overlaps a portion of the transparent substrate (TS). Also, in the second pattern (P2), the first-second opening (OP1-2) and the second-second opening (OP2-2) expose the top surface of the transparent substrate (TS). A phase shifter (PSM) is disposed below the etching stopper film (ESM). Since the first-second opening (OP1-2) and the second-second opening (OP2-2) are identical in size, only a portion of the top surface of the transparent substrate (TS) is exposed in the second pattern (P2). Therefore, during the exposure process, light incident on the region of the second pattern (P2) located within the first-second opening (OP1-2) and the second-second opening (OP2-2) can only pass through the transparent substrate (TS) of the photomask. In addition, light incident on the area of ​​the second pattern (P2) located outside the first-2 opening (OP1-2) and the second-2 opening (OP2-2) can reach the etch stop layer (ESM) of the photomask. As described above, the light transmittance of the double layer consisting of the phase shift layer (PSM) and the etch stop layer (ESM) can be adjusted, so the light reaching the etch stop layer (ESM) is blocked.

[0071] In one embodiment, the planar shape of each of the first-2 opening (OP1-2) and the second-2 opening (OP2-2) is a rectangle. That is, the shape of a portion of the top surface of the phase shifter (PSM) exposed through the first-2 opening (OP1-2) and the second-2 opening (OP2-2) has a rectangle in plan. However, the present invention is not limited thereto, and the planar shape of each of the first-2 opening (OP1-2) and the second-2 opening (OP2-2) may have various shapes, such as a polygonal shape or a circular shape.

[0072] 6 to 12 are cross-sectional views showing a method for manufacturing the photomask in FIG.

[0073] Hereinafter, explanations that overlap with the configurations explained with reference to FIGS. 1 to 3 will be omitted.

[0074] As shown in Figure 6, a preliminary phase shifter film (PSM') is formed on a transparent substrate (TS). For example, the preliminary phase shifter film (PSM') entirely covers the transparent substrate (TS). The preliminary phase shifter film (PSM') includes the same material as the phase shifter film (PSM) of Figure 3. In one embodiment, the preliminary phase shifter film (PSM') includes chromium, chromium oxide, chromium nitride, etc. These may be used alone or in combination.

[0075] A preliminary etch stop layer (ESM') is formed on the preliminary phase shift layer (PSM'). For example, the preliminary etch stop layer (ESM') entirely covers the preliminary phase shift layer (PSM'). The preliminary etch stop layer (ESM') comprises the same material as the etch stop layer (ESM) of FIG. 3. In one embodiment, the preliminary etch stop layer (ESM') comprises molybdenum, silicon, zirconium, silicon, or the like, which may be used alone or in combination.

[0076] A preliminary light-shielding film (LBM') is formed on the preliminary etch stop film (ESM'). For example, the preliminary light-shielding film (LBM') entirely covers the preliminary etch stop film (ESM'). The preliminary light-shielding film (LBM') contains the same material as the light-shielding film (LBM) of FIG. 3. For example, the preliminary light-shielding film (LBM') contains chromium.

[0077] A preliminary phase shifter (PSM'), a preliminary etch stopper (ESM'), and a preliminary light-shielding film (LBM') are sequentially formed on a transparent substrate (TS) to form a blank mask (BM). The blank mask (BM) is a mask used to manufacture the photomask (PM) shown in FIG.

[0078] As shown in FIGS. 7 and 8, a first photoresist layer (PRL1) is formed on the blank mask (BM) of FIG. 6. The first photoresist layer (PRL1) is formed on the preliminary light-shielding film (LBM'). For example, the first photoresist layer (PRL1) entirely covers the preliminary light-shielding film (LBM'). The first photoresist layer (PRL1) is formed by a spin coating, spraying, immersion, or other process. However, the method for forming the first photoresist layer (PRL1) is not limited thereto.

[0079] In one embodiment, the first photoresist layer (PRL1) includes a photosensitive organic material, for example, a positive photoresist, or a negative photoresist.

[0080] After the first photoresist layer (PRL1) is formed, a portion of the first photoresist layer (PRL1) is removed on the blank mask to form a first photoresist pattern (PRP1). The first photoresist pattern (PRP1) is formed by removing a portion of the first photoresist layer (PRL1) through an exposure process and development. A portion of the top surface of the preliminary light-shielding film (LBM') is exposed through the portion where the first photoresist layer (PRL1) has been removed.

[0081] If the first photoresist layer (PRL1) is a positive photoresist, an exposure process is performed on the remaining portion of the first photoresist layer (PRL1) except for the portion where the first photoresist pattern (PRP1) is located, and after the exposure process, the remaining portion of the first photoresist layer (PRL1) is removed by development.

[0082] If the first photoresist layer (PRL1) is a negative photoresist, an exposure process is performed on the portion of the first photoresist layer (PRL1) where the first photoresist pattern (PRP1) is located, and after the exposure process, the remaining portion of the first photoresist layer (PRL1) except for the portion where the first photoresist pattern (PRP1) is located is removed by development.

[0083] 8 and 9, portions of the preliminary light-shielding film (LBM') and the etching stop film (ESM') are removed along the first photoresist pattern (PRP1). For example, portions of the preliminary light-shielding film (LBM') and the etching stop film (ESM') are removed by an etching process. Portions of the preliminary light-shielding film (LBM') and the etching stop film (ESM') that do not overlap with the first photoresist pattern (PRP1) are removed by the etching process.

[0084] A first preliminary opening (OP1') is formed penetrating the preliminary light-shielding film (LBM') and the etching stop film (ESM'). The first preliminary opening (OP1') corresponds to the second opening (OP2) and the third opening (OP3) in FIG. 3. Specifically, the portion of the first preliminary opening (OP1') located in the phase shift area (PSA) and penetrating the etching stop film (ESM) corresponds to the opening 2-1 (OP2-1) in FIG. 3. The portion of the first preliminary opening (OP1') located in the light-shielding area (LBA) and penetrating the etching stop film (ESM) corresponds to the opening 2-2 (OP2-2). The portion of the first preliminary opening (OP1') located in the phase shift area (PSA) and penetrating the light-shielding film (LBM) corresponds to the third opening (OP3) in FIG. 3.

[0085] The first preliminary opening (OP1') is formed across the phase shift area (PSA) and the light blocking area (LBA). The first preliminary opening (OP1') exposes a portion of the top surface of the preliminary phase shift film (PSM'). The first preliminary opening (OP1') is formed through the preliminary etch stop film (ESM'), thereby forming the etch stop film (ESM).

[0086] During the etching process, the preliminary etch stop layer (ESM') has a relatively faster etching rate than the preliminary phase shift layer (PSM'), so that the preliminary phase shift layer (PSM') is not etched during the etching process.

[0087] 10 and 11, a second photoresist layer (PRL2) is formed on the etch stop layer (ESM) in the phase shift area (PSA). Specifically, in the phase shift area (PSA), the second photoresist layer (PRL2) entirely covers the preliminary light blocking layer (LBM') and the etch stop layer (ESM). The second photoresist layer (PRL2) is not formed in the light blocking area (LBA).

[0088] The second photoresist layer (PRL2) is formed by spin coating, spraying, dipping, etc. However, in the present invention, the method for forming the second photoresist layer (PRL2) is not limited to these.

[0089] In one embodiment, the second photoresist layer (PRL2) comprises a photosensitive organic material. For example, the photosensitive organic material may comprise a positive photoresist. Alternatively, the photosensitive organic material may comprise a negative photoresist.

[0090] After the second photoresist layer (PRL2) is formed, a portion of the second photoresist layer (PRL2) is removed to form a second photoresist pattern (PRP2). By forming the second photoresist layer (PRL2) in the phase shift area (PSA), the second photoresist pattern (PRP2) is also formed in the phase shift area (PSA). The second photoresist pattern (PRP2) exposes a portion of the top surface of the phase shift film (PSM).

[0091] If the second photoresist layer (PRL2) is a positive photoresist, an exposure process is performed on the remaining part of the second photoresist layer (PRL2) except for the part where the second photoresist pattern (PRP2) is located, and after the exposure process, the remaining part of the second photoresist layer (PRL2) is removed by development.

[0092] If the second photoresist layer (PRL2) is a negative photoresist, an exposure process is performed on the portion of the second photoresist layer (PRL2) where the second photoresist pattern (PRP2) is located, and after the exposure process, the remaining portion of the second photoresist layer (PRL2) except for the portion where the second photoresist pattern (PRP2) is located is removed by development.

[0093] 11 and 12, in the phase shift area (PSA), a portion of the preliminary phase shift film (PSM') is removed by the second photoresist pattern (PRP2) to form the phase shift film (PSM). A portion of the preliminary phase shift film (PSM') is removed by an etching process.

[0094] A second preliminary opening (OP2') is defined in the phase shift film (PSM) to expose a portion of the top surface of the transparent substrate (TS). That is, the preliminary phase shift film (PSM') is removed, and the second preliminary opening (OP2') is formed penetrating the preliminary phase shift film (PSM'). The second preliminary opening (OP2') corresponds to the first opening (OP1) in FIG. 3. Specifically, the portion of the second preliminary opening (OP2') located in the phase shift area (PSA) and penetrating the phase shift film (PSM) corresponds to the opening 1-1 (OP1-1) in FIG. 3. The portion of the second preliminary opening (OP2') located in the light-shielding area (LBA) and penetrating the phase shift film (PSM) corresponds to the opening 1-2 (OP1-2) in FIG. 3.

[0095] In the phase shift area (PSA), the size of the second preliminary opening (OP2') is larger than the size of the first preliminary opening (OP1'). In the light blocking area (LBA), the size of the second preliminary opening (OP2') is substantially the same as the size of the first preliminary opening (OP1').

[0096] After the step of removing the second photoresist pattern (PRP2), the photomask (PM) of FIG. 3 is fabricated.

[0097] 8 and 11, in the photomask manufactured through two exposure processes for forming the first and second photoresist patterns (PRP1, PRP2), the sizes of the first preliminary opening (OP1') and the second preliminary opening (OP2') in the light-shielding area (LBA) are substantially the same. As a result, during the process of manufacturing the display device (DD) of FIG. 2, light incident on the light-shielding area (LBA) and passing through the phase shift film (PSM) also passes through the etching stop film (ESM), preventing the phase of the light from being inverted in the light-shielding area (LBA).

[0098] FIG. 13 is a cross-sectional view showing another example of a cross section taken along line II' in FIG.

[0099] The configuration of the photomask (PM) described in Fig. 13 is the same as the configuration of the photomask (PM) in Fig. 3 except for the light-shielding film (LBM). In the following, the content that overlaps with the content described in Fig. 3 will be omitted.

[0100] As shown in Figure 13, the photomask (PM) includes a transparent substrate (TS), a phase shift film (PSM), and an etching stop film (ESM) in the phase shift area (PSA) and the light blocking area (LBA). The size of the opening 2-1 (OP2-1) is smaller than the size of the opening 1-1 (OP1-1). The size of the opening 2-2 (OP2-2) is substantially the same as the size of the opening 1-2 (OP1-2).

[0101] When light incident on the phase shift area (PSA) in the third direction (DR3) passes through the transparent substrate (TS) and the phase shift film (PSM) and reaches the etching stop film (ESM), the light is blocked.

[0102] FIG. 14 is an enlarged plan view showing another example of the first pattern in FIG.

[0103] The configuration within the first pattern (P1) described in Fig. 14 is the same as the remaining configuration within the first pattern (P1) in Fig. 4, excluding the light-shielding film (LBM) and the etching stop film (ESM). In the following, the content that overlaps with the content described in Fig. 5 will be omitted.

[0104] As shown in Figure 14, in the first pattern (P1), the etching stop layer (ESM) overlaps a portion of the phase shift layer (PSM). In the first pattern (P1), a second opening (OP2-1) is defined in the etching stop layer (ESM), exposing a portion of the top surface of each of the phase shift layer (PSM) and the transparent substrate (TS). In the first pattern (P1), the light-shielding layer (LBM) of Figure 3 is not disposed on the etching stop layer (ESM).

[0105] In one embodiment, the planar shape of the opening 2-1 (OP2-1) is a rectangle. That is, the shape of a portion of the upper surface of the phase shifter (PSM) exposed through the opening 2-1 (OP2-1) has a rectangle in plan. However, the present invention is not limited thereto, and the planar shape of the opening 2-1 (OP2-1) may have various shapes, such as a polygonal shape or a circular shape.

[0106] 13 is the same as the second pattern (P2) in FIGS.

[0107] 15 to 17 are cross-sectional views showing a method for manufacturing the photomask in FIG.

[0108] The description of the process for manufacturing the photomask (PM) in Fig. 13 is the same as that described with reference to Figs. 6 to 9. Hereinafter, the same content as that described with reference to Figs. 6 to 9 will be omitted.

[0109] As shown in Figures 15 and 16, a second photoresist layer (PRL2') is formed on the etch stop layer (ESM) in the phase shift area (PSA). Specifically, in the phase shift area (PSA), the second photoresist layer (PRL2') covers a portion of the preliminary light-shielding layer (LBM') and the etch stop layer (ESM). In other words, the second photoresist layer (PRL2') does not entirely cover the preliminary light-shielding layer (LBM'). Furthermore, the second photoresist layer (PRL2') is not formed in the light-shielding area (LBA).

[0110] The second photoresist layer (PRL2') is formed by a spin coating, spraying, dipping (immersion) process, etc. However, in the present invention, the method for forming the second photoresist layer (PRL2') is not limited to these.

[0111] In one embodiment, the second photoresist layer (PRL2') comprises a photosensitive organic material, for example, a positive photoresist, or a negative photoresist.

[0112] After the second photoresist layer (PRL2') is formed, a portion of the second photoresist layer (PRL2') is removed to form a second photoresist pattern (PRP2'). By forming the second photoresist layer (PRL2') in the phase shift area (PSA), the second photoresist pattern (PRP2') is also formed in the phase shift area (PSA). The second photoresist pattern (PRP2') exposes a portion of the top surface of the phase shift film (PSM).

[0113] If the second photoresist layer (PRL2') is a positive photoresist, an exposure process is performed on the remaining portion of the second photoresist layer (PRL2') except for the portion where the second photoresist pattern (PRL2') is located. After the exposure process, the remaining portion of the second photoresist layer (PRL2') is removed by development.

[0114] If the second photoresist layer (PRL2') is a negative photoresist, an exposure process is performed on the portion of the second photoresist layer (PRL2') where the second photoresist pattern (PRP2') is located. After the exposure process, the remaining portion of the second photoresist layer (PRL2') except for the portion where the second photoresist pattern (PRP2') is located is removed by development.

[0115] As shown in Figure 17, in the phase shift area (PSA), a portion of the preliminary phase shift film (PSM') is removed by the second photoresist pattern (PRP2') to form the phase shift film (PSM). Also, the preliminary light-shielding film (LBA') located in the phase shift area (PSA) is entirely removed. The preliminary light-shielding film (LBA') and a portion of the preliminary phase shift film (PSM') are removed by an etching process.

[0116] A second preliminary opening (OP2') is defined in the phase shift film (PSM) to expose a portion of the top surface of the transparent substrate (TS). That is, the preliminary phase shift film (PSM') is removed to form the second preliminary opening (OP2') penetrating the preliminary phase shift film (PSM'). The second preliminary opening (OP2') corresponds to the first opening (OP1) in FIG. 13. Specifically, the portion of the second preliminary opening (OP2') located in the phase shift area (PSA) and penetrating the phase shift film (PSM) corresponds to the opening 1-1 (OP1-1) in FIG. 13. The portion of the second preliminary opening (OP2') located in the light-shielding area (LBA) and penetrating the phase shift film (PSM) corresponds to the opening 1-2 (OP1-2) in FIG. 13.

[0117] In the phase shift area (PSA), the size of the second preliminary opening (OP2') is larger than the size of the first preliminary opening (OP1'). In the light blocking area (LBA), the size of the second preliminary opening (OP2') and the size of the first preliminary opening (OP1') are substantially the same.

[0118] As a result, after the step of removing the second photoresist pattern (PRP2'), the photomask (PM) of FIG. 13 is manufactured.

[0119] According to a preferred embodiment:

[0120] The background to this case is as follows (i) to (iv). (i) When manufacturing display panels that have an array of organic light-emitting diodes (OLEDs) or micro LEDs, photomasks are required for the fine exposure process. (ii) In particular, as image display resolution increases, the width of wiring and the size of contact holes within the display area become smaller, which requires higher resolution in the exposure process. Furthermore, even higher resolution is required for next-generation displays such as eyeglass-type displays.

[0121] (iii) As a measure for realizing high definition in the exposure process, it has been considered to provide a window along the periphery of the transmission window portion (for example, Patent Document 1). (iv) Patent Document 1 proposes superposing a "light-semitransmitting film" (22) and a "light-shielding etching mask film made of a metal silicide material" (23) on a transparent substrate (21) in order to "strictly control the cross-sectional shape of the edge portion of the chromium-based phase shift film pattern."

[0122] The present inventors have conducted extensive research into improving the exposure process and photomask for achieving higher definition, and have found the following problems (a1) to (a3).

[0123] (a1) For example, a display area including sub-pixel light-emitting portions and a non-display area adjacent to the display area are arranged on the display screen of a display panel, where fine contact holes for connecting transistors and capacitors of pixel circuits to pixel electrodes are arranged in the display area, and relatively large contact holes for supplying power to a common electrode are arranged in the non-display area.

[0124] (a2) In order to form contact holes and wiring that connect transistors, etc. in pixel circuits with pixel electrodes, etc., it is desirable that the change in light transmittance between the light-transmitting area and the light-shielding area be steep so that the edges of the metal pattern are sharp. In contrast, in the case of power supply contact holes in non-display areas, it may be preferable that the sidewalls be gently tapered, so that the conductive pattern covering the sidewalls has good coverage.

[0125] (a3) In a conventional photomask with a phase shift region formed by the method of Patent Document 1, the phase shift film may protrude like a shelf into the light-transmitting window even at the edge of the contact hole in the non-display region, which may prevent the desired tapered sidewall from being obtained.

[0126] Therefore, according to a particularly preferred embodiment, any combination of A1 to A3 or A1 to A8 below is used. A1: A phase shift film (PSM') and an etching stop film (ESM') are laminated in this order on a transparent substrate (TS) made of glass or the like (Fig. 6 of the present application).

[0127] A2: A "preliminary opening (OP1')" is formed through the phase shift film (PSM') and the etching stop film (ESM') by patterning using a photoresist (Figs. 7 to 9 of the present application).

[0128] A3 By placing photoresist only in the display area (phase shift area (PSA)) and patterning it, the phase shift film (PSM) extends beyond the inner edge of the etching stop film (ESM) into the transparent window corresponding to the contact holes and wiring in the display area. On the other hand, in the transmission window corresponding to the power supply contact hole in the non-display area, the inner edge of the phase shift film (PSM) coincides with the inner edge of the etching stop film (ESM). (Figures 10-12 and 16-17 of the present application)

[0129] In the A4 display area (phase shift area (PSA)), a light-shielding film (LBM) can be superimposed on a phase shift film (PSM).

[0130] A5 Phase shifting films (PSM) are made of chromium (Cr), chromium oxide (CrOx), chromium nitride (CrNx), etc.

[0131] A6 Etch stop films (ESM) are made of molybdenum (Mo), silicon (Si), zirconium (Zr), silicon (Si), etc.

[0132] A7 The thickness of the etch stop film (ESM') may be 45 nm or more, 47 nm or more, or 50.2 nm or more, and typically 150 nm or less, or 100 nm or less.

[0133] A8 The product of the optical transmittance of the phase shift film (PSM) and the optical transmittance of the etching stop film (ESM) is 0.0010% or more and 0.10% or less, and the optical density of the double film consisting of the phase shift film (PSM) and the etching stop film (ESM) is 3.0 or more and 5.0 or less. [Industrial Applicability]

[0134] The present invention can be used in the manufacture of display devices and electronic devices including the same, such as high-resolution smartphones, mobile phones, smart pads, smart watches, tablet PCs, vehicle navigation systems, televisions, computer monitors, and laptops.

[0135] Although the present invention has been described above with reference to exemplary embodiments, those skilled in the art will recognize that various modifications and variations can be made thereto without departing from the spirit and scope of the invention as set forth in the following claims. [Explanation of symbols]

[0136] PM: Photomask PSA: Phase reversal area LBA: Light-Blocking Area TS: Transparent substrate PSM: Phase shift film ESM: Etch Stop Film LBM: Light blocking film P1: First pattern P2: Second pattern DD: Display device PSM': Preliminary phase shift film ESM': Pre-etch stop layer LBM': spare light blocking film PRL1: First photoresist layer PRL2, PRL2': second photoresist layer PRP1: First photoresist pattern PRP2: Second photoresist pattern OP1: First opening OP1-1: Opening 1-1 OP1-2: Opening 1-2 OP2: Second opening OP2-1: Opening 2-1 OP2-2: Opening 2-2 OP3: Third opening

Claims

1. a transparent substrate including a phase shift region and a light blocking region adjacent to the phase shift region; a phase shift film disposed in the phase shift region and the light blocking region on the transparent substrate, the phase shift film defining a first opening exposing the upper surface of the transparent substrate in the phase shift region and a second opening exposing the upper surface of the transparent substrate in the light blocking region; and an etching stop layer disposed in the phase shift region and the light-shielding region on the phase shift film, the etching stop layer defining a second-1 opening exposing the first-1 opening and a second-2 opening exposing the first-2 opening.

2. 2. The photomask of claim 1, wherein the etching stop layer has a thickness of 450 Å or more.

3. 2. The photomask of claim 1, wherein the light transmittance of the phase shift film is between 3.0% and 50%.

4. 4. The photomask of claim 3, wherein the product of the optical transmittance of the phase shift film and the optical transmittance of the etch stop film is 0.10% or less.

5. 2. The photomask of claim 1, wherein the size of the first-2 opening is substantially the same as the size of the second-2 opening.

6. 2. The photomask of claim 1, further comprising a light-shielding film disposed on the etching stop film and overlapping the phase shift region.

7. forming a preliminary phase shift film on a transparent substrate including a phase shift region and a light-shielding region adjacent to the phase shift region, the preliminary phase shift film overlapping the phase shift region and the light-shielding region; forming a preliminary etch stop layer on the preliminary phase shift film so as to overlap the phase shift region and the light blocking region; forming a preliminary light-shielding layer on the preliminary etch stop layer so as to overlap the phase shift region and the light-shielding region; removing a portion of the preliminary phase shift film to form a phase shift film defining a first opening exposing the top surface of the transparent substrate in the phase shift region and a second opening exposing the top surface of the transparent substrate in the light-shielding region; and removing at least a portion of the preliminary light-shielding film and a portion of the preliminary etching stop film to form an etching stop film defining a second-first opening exposing the first-first opening and a second-second opening exposing the first-second opening.

8. The step of forming the etch stop layer comprises: forming a first photoresist layer on the preliminary light-shielding film; removing a portion of the first photoresist layer to form a first photoresist pattern; removing a portion of each of the preliminary etch stop layer and the preliminary light-shielding layer using the first photoresist pattern; forming the second-1 opening and the second-2 opening penetrating the preliminary etch stop layer in a thickness direction and exposing a portion of an upper surface of the preliminary phase shift layer; 8. The method of claim 7, further comprising forming a third opening that penetrates the preliminary light-shielding film in a thickness direction and exposes the second-1 opening.

9. The step of forming the phase shift film comprises: forming a second photoresist layer on the etch stop layer overlapping the phase shift region to fill the second opening; removing a portion of the second photoresist layer to form a second photoresist pattern; removing a portion of the preliminary phase shift film using the second photoresist pattern to form the first-1 opening that penetrates the phase shift film in a thickness direction and exposes the top surface of the transparent substrate; 9. The method of claim 8, further comprising forming the first and second openings through the phase shift film in a thickness direction to expose the top surface of the transparent substrate.

10. After the step of forming the second photoresist pattern, 10. The method for manufacturing a photomask according to claim 9, wherein the preliminary light-shielding film overlapping the phase shift region and the light-shielding region is entirely removed.

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