Phase shift mask, manufacturing method thereof and manufacturing method of display device

Abstract

A phase-shift mask substrate is provided that, even when the phase-shift film exhibits film thickness fluctuations, it can suppress transmittance fluctuations relative to the representative wavelength of the exposure light, achieving the desired high transmittance and enabling good pattern transfer. The phase-shift mask substrate has a phase-shift film on a transparent substrate. At the representative wavelength of the exposure light, the phase-shift film has a transmittance of 30% or more and 80% or less, an attenuation coefficient k of 0.10 or more and 0.25 or less, a refractive index n of 2.20 or more and 2.57 or less, and the representative wavelength is in the range of 313–436 nm. The representative wavelength, in the relationship between the surface reflectance and wavelength of the phase-shift film, is located between the valley of the surface reflectance on the adjacent short wavelength side and the peak of the surface reflectance on the adjacent long wavelength side. The phase-shift film contains a transition metal and silicon.

Description

Technical Field

[0001] This invention relates to a phase-shifting mask base plate, a phase-shifting mask, a method for manufacturing a phase-shifting mask, and a method for manufacturing a display device. Background Technology

[0002] In recent years, display devices such as FPDs (Flat Panel Displays), represented by OLEDs (Organic Light Emitting Diodes), have seen a gradual increase in size, wider viewing angles, higher resolution, and faster display speeds. As a key factor in achieving higher resolution and faster display speeds, it is necessary to fabricate electronic circuit patterns for components or wiring with extremely fine dimensions and high precision. The patterning of electronic circuits in these display devices is mostly done using photolithography. Therefore, photolithographic masks such as phase-shift masks and binary masks are needed to form these fine and high-precision patterns for display device manufacturing.

[0003] For example, Patent Document 1 discloses a phase-shifting mask in which a mask pattern formed on a transparent substrate is constructed by a light-transmitting portion that transmits light of substantially high intensity that contributes to exposure and a light-semi-transmitting portion that transmits light of substantially low intensity that does not contribute to exposure. Furthermore, by shifting the phase of the light passing through the light-semi-transmitting portion, the phase of the light passing through the light-semi-transmitting portion is different from the phase of the light passing through the light-transmitting portion. This allows the light passing near the junction of the light-transmitting portion and the light-semi-transmitting portion to cancel each other out, thereby maintaining the contrast of the junction well.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 6-332152 Summary of the Invention

[0007] The technical problem that the invention aims to solve

[0008] As phase-shift masks have been used in the manufacturing of high-resolution (600ppi and above) panels in recent years, in order to transfer high-resolution patterns, phase-shift masks are required to form fine phase-shift film patterns with apertures of 6μm or less and linewidths of 4μm or less. Specifically, phase-shift masks with fine phase-shift film patterns with apertures of 1.5μm are required.

[0009] Furthermore, in order to achieve higher resolution pattern transfer, a phase shift mask substrate with a high transmittance phase shift film of more than 30% relative to the exposure light and a phase shift mask with a phase shift film pattern having a transmittance of more than 30% relative to the exposure light are required.

[0010] Moreover, it is not easy to stabilize the film formation conditions of such a phase-shifting film, and fluctuations (deviations) are likely to occur in the film thickness of the formed phase-shifting film.

[0011] Furthermore, when fabricating a phase shift mask by forming fine patterns on a phase shift mask substrate with such a phase shift film, cleaning and etching processes are performed. Additionally, the fabricated phase shift mask undergoes appropriate cleaning before use. For these reasons, the thickness of the patterned phase shift film formed in the phase shift mask is reduced.

[0012] Furthermore, there are cases where the transmittance of the phase-shifting film fluctuates significantly due to variations in the film thickness of such a phase-shifting film (including patterned phase-shifting films, the same below), which can affect the desired transfer characteristics.

[0013] Therefore, the present invention was made to solve the above-mentioned technical problems, and its object is to provide a phase shift mask substrate, a phase shift mask, a method for manufacturing a phase shift mask, and a method for manufacturing a display device, which can suppress the fluctuation of transmittance relative to the representative wavelength of the exposure light and have the desired high transmittance even when the phase shift film thickness fluctuates, and can perform good pattern transfer.

[0014] Technical solutions for solving technical problems

[0015] The present invention was made to solve the above-mentioned technical problems and has the following solution.

[0016] (Solution 1) A phase-shifting mask base plate having a phase-shifting film on a transparent substrate, characterized in that,

[0017] The phase-shifting film, at a representative wavelength of the exposure wavelength, has a transmittance of 30% or more and 80% or less, an attenuation coefficient k of 0.10 or more and 0.25 or less, and a refractive index n of 2.20 or more and 2.57 or less.

[0018] The representative wavelength of the exposure wavelength is in the range of 313–436 nm.

[0019] The representative wavelength, in the relationship between the surface reflectance and wavelength of the phase-shifting film, lies between the valley of the surface reflectance on the adjacent short wavelength side and the peak of the surface reflectance on the adjacent long wavelength side.

[0020] The phase-shifting film contains a transition metal and silicon.

[0021] (Scheme 2) According to the phase shift mask base plate of Scheme 1, the phase shift film contains light elements, and the content of the light elements is more than 50 atomic%.

[0022] (Solution 3) According to the phase shift mask base plate described in Solution 1 or 2, the phase shift film is a single-layer film or a laminated film composed of the same component.

[0023] (Scheme 4) According to the phase shift mask substrate comprising any one of 1 to 3, the phase shift film has a thickness of 180 nm or less.

[0024] (Solution 5) According to any one of Solutions 1 to 4, for the phase shifting film, when the film thickness fluctuates within the range of less than 30 nm, the difference between the maximum and minimum values ​​of the back reflectivity relative to the representative wavelength is more than 10%.

[0025] (Solution 6) According to any one of Solutions 1 to 5, for the phase shifting mask substrate, when the transmittance fluctuation value is the difference between the maximum and minimum transmittance at the representative wavelength when the film thickness fluctuates within a range of less than 30 nm, the ratio of the transmittance fluctuation value to the transmittance at the representative wavelength before the film thickness fluctuates is less than 20%.

[0026] (Scheme 7) The phase shift mask base plate according to any one of Schemes 1 to 6, wherein the representative wavelength is 405nm.

[0027] (Solution 8) According to any one of Solutions 1 to 7, the phase shift mask substrate has an etching mask on the phase shift film with different etching selectivity relative to the phase shift film.

[0028] (Solution 9) A method for manufacturing a phase-shifting mask, characterized by having:

[0029] The process of preparing the phase shift mask base plate as described in any one of schemes 1 to 7;

[0030] The process of forming a resist film on the phase-shifting film, performing wet etching on the phase-shifting film using the resist film pattern formed from the resist film as a mask, and forming a phase-shifting film pattern on the transparent substrate.

[0031] (Solution 10) A method for manufacturing a phase-shifting mask, characterized by having:

[0032] The process of preparing the phase shift mask base plate as described in Scheme 8;

[0033] The process of forming a resist film on the etching mask film, performing wet etching on the etching mask film using the resist film pattern formed from the resist film as a mask, and forming an etching mask film pattern on the phase shift film;

[0034] The process of forming a phase-shifting film pattern on a transparent substrate by wet etching the phase-shifting film using the etched mask film pattern as a mask.

[0035] (Solution 11) A phase-shifting mask having a patterned phase-shifting film on a transparent substrate, characterized in that,

[0036] The phase-shifting film, at a representative wavelength of the exposure wavelength, has a transmittance of 30% or more and 80% or less, an attenuation coefficient k of 0.10 or more and 0.25 or less, and a refractive index n of 2.20 or more and 2.57 or less.

[0037] The representative wavelength of the exposure wavelength is in the range of 313–436 nm.

[0038] The representative wavelength, in the relationship between the surface reflectance and wavelength of the phase-shifting film, lies between the valley of the surface reflectance on the adjacent short wavelength side and the peak of the surface reflectance on the adjacent long wavelength side.

[0039] The phase-shifting film contains a transition metal and silicon.

[0040] (Scheme 12) According to the phase shift mask described in Scheme 11, the phase shift film contains light elements, and the content of the light elements is more than 50 atomic%.

[0041] (Scheme 13) According to Scheme 11 or 12, the phase shifting film is a single-layer film or a stacked film composed of the same component.

[0042] (Scheme 14) According to the phase shift mask described in Scheme 11 or 12, the thickness of the phase shift film is less than 180 nm.

[0043] (Solution 15) According to the phase shift mask described in Solution 11 or 12, for the phase shift film, when the film thickness fluctuates within the range of less than 30 nm, the difference between the maximum and minimum values ​​of the back reflectivity relative to the representative wavelength is more than 10%.

[0044] (Solution 16) According to the phase shift mask described in Solution 11 or 12, for the phase shift film, when the difference between the maximum and minimum values ​​of the transmittance at the representative wavelength is taken as the transmittance fluctuation value when the film thickness fluctuates within a range of less than 30 nm, the ratio of the transmittance fluctuation value to the transmittance at the representative wavelength before the film thickness fluctuates is less than 20%.

[0045] (Solution 17) A method for manufacturing a display device, characterized in that,

[0046] It includes an exposure process in which a phase shift mask obtained by the manufacturing method of the phase shift mask described in Scheme 9 or 10 is placed on the mask stage of the exposure apparatus, and a transfer pattern formed on the phase shift mask is exposed and transferred onto a resist formed on the substrate of the display device.

[0047] (Solution 18) A method for manufacturing a display device, characterized in that,

[0048] The device includes an exposure process in which a phase-shifting mask, as described in any one of Schemes 11 to 16, is placed on the mask stage of the exposure apparatus, and a transfer pattern formed on the phase-shifting mask is exposed and transferred onto a resist formed on a display device substrate.

[0049] The effects of the invention

[0050] According to the phase-shifting mask substrate of the present invention, even when the phase-shifting film thickness fluctuates, it can suppress the fluctuation of transmittance relative to the representative wavelength of the exposure light and achieve the desired high transmittance, and can perform good pattern transfer.

[0051] Furthermore, according to the method for manufacturing a phase-shifting mask according to the present invention, the phase-shifting mask is manufactured using the aforementioned phase-shifting mask substrate. Therefore, even when the phase-shifting film contained in the phase-shifting film pattern experiences film thickness fluctuations, it is possible to suppress fluctuations in transmittance relative to the representative wavelength of the exposure light and achieve the desired high transmittance, thus manufacturing a phase-shifting mask capable of good pattern transfer. This phase-shifting mask, for example, can handle the miniaturization of line and spatial patterns, hole patterns, and dot patterns.

[0052] Furthermore, according to the phase-shift mask of the present invention, even when the phase-shift film containing the phase-shift film pattern experiences film thickness fluctuations, it is possible to obtain a phase-shift mask that suppresses fluctuations in transmittance relative to the representative wavelength of the exposure light and has the desired high transmittance, and is capable of good pattern transfer.

[0053] Furthermore, according to the manufacturing method of the display device of the present invention, the display device is manufactured using a phase shift mask obtained by the manufacturing method of the phase shift mask described above. Therefore, for example, it is possible to manufacture display devices with fine linewidth and grating spacing patterns and contact holes. Attached Figure Description

[0054] Figure 1 This is a schematic diagram showing the film structure (transparent substrate / phase shift film / etched mask film) of the phase shift mask substrate in Embodiment 1.

[0055] Figure 2 This is a schematic diagram showing the film structure (transparent substrate / phase shift film) of the phase shift mask substrate in Embodiment 2.

[0056] Figure 3 (a) to (e) are schematic diagrams illustrating the manufacturing process of the phase shift mask in Embodiment 3.

[0057] Figure 4 (a) to (c) are schematic diagrams illustrating the manufacturing process of the phase shift mask in Embodiment 4.

[0058] Figure 5 It is a graph showing the relationship between reflectivity and transmittance and the wavelength of the exposure light in the phase-shift film corresponding to Example 1, derived from the simulation results.

[0059] Figure 6 It is a graph showing the relationship between back surface reflectance, transmittance, phase and film thickness in the phase-shifting film corresponding to Example 1, derived from the simulation results.

[0060] Figure 7 It is a graph showing the relationship between back reflectance, transmittance, phase and film thickness in an existing phase-shifting film, derived from simulation results. Detailed Implementation

[0061] First, the process of obtaining this invention will be described. The inventors of this invention conducted intensive research to solve the aforementioned technical problems. It should be noted that this research originated from the inventors' speculations and insights, but is not intended to limit the scope of this invention. The phase-shifting film in this invention is a film that shifts the phase of exposure light; the phase-shifting mask substrate and the phase-shifting mask are obtained using this phase-shifting film. The phase shift amount of the aforementioned phase-shifting film (referred to as the absolute value of the phase shift amount in this specification) only needs to be less than 0° at the representative wavelength of the exposure light, without particular limitation, but preferably approximately 180°. Approximately 180° means 160° or more and 200° or less. Preferably, the angle is 170° or higher and 190° or lower. In this specification, the phase shift will also be referred to as the phase difference.

[0062] As described above, in high-transmittance phase-shift films, film thickness fluctuations can occur, for example, during film deposition or the fabrication of the phase-shift mask. Therefore, the inventors of this invention have investigated a structure for a phase-shift film that can suppress fluctuations in transmittance relative to the representative wavelength of the exposure light, even when film thickness fluctuations occur, thereby ensuring high transmittance. It should be noted that, unless otherwise specified, in this specification, transmittance (%) values ​​are defined as 100% transmittance in the area exposed by the transparent substrate.

[0063] First, use Figure 6 and Figure 7 Please provide an explanation. Figure 6 This is a graph showing the relationship between back surface reflectivity, transmittance, phase shift amount, and film thickness in the phase-shift film corresponding to Example 1 (details described later), derived from simulation results. The phase-shift film corresponding to Example 1 has its refractive index and attenuation coefficient set in a way that achieves the desired optical properties (phase shift amount, transmittance, etc.), thereby varying the film thickness. Figure 7This is a graph illustrating an example of the relationship between back surface reflectance, transmittance, phase shift, and film thickness in an existing phase-shifting film, derived from simulation results.

[0064] exist Figure 7 In the phase-shifted film shown, almost no increase or decrease in back surface reflectance is observed, but transmittance increases with decreasing film thickness, and fluctuations are not suppressed. On the other hand, as... Figure 6 As shown, the back reflectance of the phase-shifting film corresponding to Example 1 fluctuates significantly with the increase of its film thickness, but the transmittance remains approximately constant even if the film thickness decreases or increases. That is, the phase-shifting film according to Example 1 can suppress the fluctuation of transmittance even if the film thickness fluctuates.

[0065] Therefore, in order to obtain detailed information on the optical properties of the phase-shifting film corresponding to Example 1, the inventors of this invention obtained the wavelength dependence of reflectivity and transmittance through simulation. The results are as follows: Figure 5 As shown. Figure 5 This is a graph showing the relationship between reflectivity and transmittance and the wavelength of the exposure light in the phase-shift film corresponding to Example 1. Here, reflectivity refers to the surface reflectivity of the phase-shift film (surface reflectivity). The refractive index, attenuation coefficient, and film thickness of this phase-shift film are set to obtain the desired optical properties (phase shift, transmittance, etc.). Figure 5 The example shown is for a film thickness of 153 nm. It should be noted that the transmittance here is calculated with atmospheric transmittance as a reference (100%).

[0066] like Figure 5 As shown, with a film thickness of 153 nm, considering light at a wavelength of 405 nm as an example, the surface reflectivity is 16%, and the transmittance is approximately 45%. Furthermore, in... Figure 5 In the surface reflectance curve, the wavelength corresponding to the minimum reflectance (also known as the valley) is 370 nm. On the other hand, although not illustrated, when the film thickness is reduced from 153 nm to 149 nm, the surface reflectance at a wavelength of 405 nm is 19%, and the transmittance is approximately 45%. Furthermore, at a film thickness of 149 nm, the wavelength corresponding to the valley of surface reflectance is 362 nm, and the surface reflectance curve of the phase-shift film with a film thickness of 153 nm (…) Figure 5 Compared to the previous simulation, it can be seen that the valley of surface reflectivity shifts towards shorter wavelengths. Furthermore, although not illustrated, simulations were performed by increasing the film thickness of the phase-shifting film from 153 nm to 157 nm. At a wavelength of 405 nm, the surface reflectivity was 14%, and the transmittance was 46%. Moreover, at a film thickness of 157 nm, the wavelength corresponding to the valley of surface reflectivity is 378 nm. The curves comparing the surface reflectivity of the phase-shifting film with a thickness of 153 nm are shown below. Figure 5 Compared to the previous method, the minimum (valley) of surface reflectivity shifts towards the longer wavelength side.

[0067] That is, according to the inventors' research, in the case of a phase-shifting film like the one in this embodiment, when the film thickness fluctuates, the valley of surface reflectance in the surface reflectance curve shifts left and right. Since the fluctuation of transmittance is offset by the increase or decrease of surface reflectance at the wavelength, the fluctuation of transmittance is suppressed. Moreover, since the surface reflectance at the wavelength increases or decreases according to the fluctuation of the film thickness of the phase-shifting film, a phase-shifting film with the characteristic that the wavelength is located between the valley and the peak (representing the maximum value) of surface reflectance in the curve showing the relationship between the wavelength of the exposed light and the surface reflectance is effective.

[0068] The inventors of this invention further investigated and discovered that, under the following conditions—that is, at the representative wavelength of the exposure wavelength, the transmittance is 30% or more and 80% or less, the attenuation coefficient k is 0.10 or more and 0.25 or less, the refractive index n is 2.20 or more and 2.57 or less, the representative wavelength of the exposure wavelength is in the range of 313 to 436 nm, and the representative wavelength is located between the valley (minimum) of the surface reflectance on the adjacent short wavelength side and the peak (maximum) of the surface reflectance on the adjacent long wavelength side—in a phase shift film containing transition metal and silicon, even when the phase shift film exhibits film thickness fluctuations, it is possible to suppress the fluctuations in transmittance relative to the representative wavelength of the exposure light and achieve the desired high transmittance, and to obtain optical properties desired for good pattern transfer.

[0069] This invention is based on the results of the above research and requires the following constituent elements.

[0070] Implementation methods 1 and 2.

[0071] In Embodiments 1 and 2, the phase-shifting mask substrate will be described. The phase-shifting mask substrate of Embodiment 1 is a master template for forming a phase-shifting mask. This phase-shifting mask has a phase-shifting film pattern on a transparent substrate, obtained by etching a phase-shifting film using an etch mask pattern with a desired pattern formed on it as a mask. Similarly, the phase-shifting mask substrate of Embodiment 2 is a master template for forming a phase-shifting mask. This phase-shifting mask has a phase-shifting film pattern on a transparent substrate, obtained by etching a phase-shifting film using a resist film pattern with a desired pattern formed on it as a mask. This etching can be either dry etching or wet etching, preferably wet etching.

[0072] Figure 1 This is a schematic diagram showing the film structure of the phase shift mask base plate 10 in Embodiment 1.

[0073] Figure 1 The phase shift mask substrate 10 shown includes a transparent substrate 20, a phase shift film 30 formed on the transparent substrate 20, and an etching mask film 40 formed on the phase shift film 30.

[0074] Figure 2 This is a schematic diagram showing the film structure of the phase shift mask base plate 10 in Embodiment 2.

[0075] Figure 2 The phase shift mask base plate 10 shown has a transparent substrate 20 and a phase shift film 30 formed on the transparent substrate 20.

[0076] The transparent substrate 20, phase shift film 30, and etched mask film 40 constituting the phase shift mask substrate 10 of Embodiment 1 and Embodiment 2 will be described below.

[0077] The transparent substrate 20 is transparent to the exposure light. Without surface reflection loss, the transparent substrate 20 has a transmittance of 85% or more, preferably 90% or more, relative to the exposure light. The transparent substrate 20 is made of a material containing silicon and oxygen, and can be made of glass materials such as synthetic quartz glass, aluminosilicate glass, soda-lime glass, or low thermal expansion glass (SiO2-TiO2 glass, etc.). When the transparent substrate 20 is made of low thermal expansion glass, positional changes in the phase-shift film pattern caused by thermal deformation of the transparent substrate 20 can be suppressed. Furthermore, the transparent substrate 20 used for display devices is generally a rectangular substrate with a shorter side length of 300 mm or more. For example, the length of one side of the main surface of the transparent substrate (the surface where the phase-shift film pattern is formed) is 300 to 2000 mm. The present invention provides a phase shift mask substrate capable of stably transferring fine phase shift film patterns, such as less than 2.0 μm, formed on a transparent substrate, even in large sizes where the short side of the transparent substrate has a length of 300 mm or more.

[0078] The transmittance of the phase-shifting film 30 relative to the exposure light satisfies the value required for the phase-shifting film 30. The transmittance of the phase-shifting film 30 relative to the light (representative wavelength) of a specified wavelength included in the exposure light is preferably 30% or more and 80% or less, more preferably 35% or more and 75% or less, and even more preferably 40% or more and 70% or less. That is, when the exposure light is a composite light containing light in the wavelength range of 313 nm or more and 436 nm or less, the phase-shifting film 30 has the above-mentioned transmittance relative to the representative wavelength contained in that wavelength range. For example, when the exposure light is a composite light of the i-line, h-line, and g-line, the phase-shifting film 30 has the above-mentioned transmittance relative to any one of the i-line, h-line, and g-line. The representative wavelength is not particularly limited to the range of 313 to 436 nm, but from the viewpoint that the relationship between the surface reflectance of the phase-shifting film and the wavelength is set between the valley of the surface reflectance on the adjacent short wavelength side and the peak of the surface reflectance on the adjacent long wavelength side, 405 nm (h-line) is preferred. By having such properties relative to the h-line, when using composite light containing the i-line, h-line, and g-line as exposure light, similar effects can be expected in terms of transmittance relative to the wavelengths of the i-line and g-line.

[0079] Transmittance can be measured using devices such as phase shift measurement equipment.

[0080] The phase difference between the phase shift film 30 and the exposure light satisfies a desired value. The phase difference of the phase shift film 30 relative to the representative wavelength of the exposure light is preferably 160° or more and 200° or less, more preferably 170° or more and 190° or less. This property allows the phase of the representative wavelength of the exposure light to be changed to 160° or more and 200° or less. Therefore, a phase difference of 160° or more and 200° or less is generated between the representative wavelength of the light transmitted through the phase shift film 30 and the representative wavelength of the light transmitted only through the transparent substrate 20. That is, when the exposure light is a composite light including light with a wavelength range of 313 nm or more and 436 nm or less, the phase shift film 30 has the aforementioned phase difference relative to the representative wavelength of its wavelength range. For example, when the exposure light is a composite light of the i-line, h-line, and g-line, the phase shift film 30 has the aforementioned phase difference relative to any one of the i-line, h-line, and g-line.

[0081] Phase difference can be measured using devices such as phase shift measuring instruments.

[0082] From the viewpoint of thinning the film to obtain the necessary phase difference and improving the etching rate, the refractive index n of the phase shift film 30 relative to the wavelength is preferably 2.20 or more and 2.57 or less, and more preferably 2.21 or more and 2.50 or less.

[0083] Furthermore, from the viewpoint of suppressing fluctuations in transmittance relative to the thickness of the phase shift film 30, the attenuation coefficient k of the phase shift film 30 relative to the representative wavelength is preferably 0.10 or more and 0.25 or less, and more preferably 0.11 or more and 0.20 or less.

[0084] Furthermore, from the perspectives of suppressing power increase and improving defect quality during film formation, shortening etching time, miniaturizing patterns, and reducing deformation caused by film stress, the thickness of the phase-shifting film 30 is preferably 180 nm or less, and more preferably 130 nm or more and 180 nm or less.

[0085] Furthermore, from the viewpoint of suppressing the fluctuation of transmittance relative to the film thickness of the phase-shifting film 30, for the phase-shifting film 30, in the relationship between surface reflectance and wavelength, it is preferable that the difference between the peak and the valley of surface reflectance is 10% or more, and more preferably 15% or more.

[0086] Furthermore, from the viewpoint of suppressing the fluctuation of transmittance caused by surface reflectance, for the phase-shifting film 30, it is preferable that the difference between the peak and the valley of surface reflectance is less than 20%.

[0087] Furthermore, from the viewpoint of further suppressing the fluctuation of transmittance relative to the film thickness of the phase-shifting film 30, for the phase-shifting film 30, when the film thickness fluctuates within a range of 30 nm or less, it is preferable that the difference between the maximum and minimum values ​​of the back reflectance at the representative wavelength is 10% or more, more preferably 15% or more. It should be noted that when the surface reflectance and the back reflectance are considered together as reflectance, in this specification, the difference X (%) between reflectance A (%) and reflectance B (%) is expressed as X = |A - B| (the absolute value of the difference between A and B), which can be denoted as X (points).

[0088] Furthermore, in order to obtain good transfer characteristics even when the film thickness fluctuates, for the phase-shifting film 30, when the difference between the maximum and minimum transmittance values ​​at a representative wavelength when the film thickness fluctuates within a range of 30 nm or less is taken as the transmittance fluctuation value, the ratio of the transmittance fluctuation value to the transmittance at the representative wavelength before the film thickness fluctuation is 20% or less, preferably 15% or less, and more preferably 10% or less. It should be noted that in this specification, the difference Y(%) between transmittance C(%) and transmittance D(%) is expressed as Y = |C - D| (the absolute value of the difference between C and D), and can also be denoted as Y(points). Moreover, the ratio of the transmittance fluctuation value to the transmittance at the representative wavelength before the film thickness fluctuation refers to the percentage value expressed as the transmittance fluctuation value divided by the transmittance at the representative wavelength before the film thickness fluctuation.

[0089] Reflectivity can be measured using a spectrophotometer or similar instrument.

[0090] The material of the phase-shifting film 30 is not particularly limited, but it is preferable that the phase-shifting film 30 contains, for example, a transition metal or silicon, and can be formed by a transition metal silicide. Suitable transition metals include molybdenum (Mo), zirconium (Zr), tantalum (Ta), tungsten (W), and titanium (Ti). Particularly preferred are ZrMoSi-type materials comprising molybdenum (Mo), zirconium (Zr), silicon (Si), and nitrogen. The use of a ZrMoSi-based material is advantageous because it facilitates obtaining a good pattern profile shape through wet etching.

[0091] Furthermore, the phase-shifting film 30 preferably contains a light element, with a light element content of 50 atomic percent or more. In this specification, a light element refers to an element with an element number lower than scandium (Sc). As a light element, it is preferable to contain at least one of nitrogen or oxygen. In the aforementioned transition metal silicide materials, oxygen, as a light element component, has the effect of reducing the refractive index and attenuation coefficient compared to nitrogen, which is also a light element component. Therefore, the content of other light element components (such as nitrogen) used to obtain the desired transmittance can be reduced, and the reflectivity of the surface and back of the phase-shifting film 30 can be effectively reduced. Furthermore, in the aforementioned transition metal silicide materials, nitrogen, as a light element component, has the effect of reducing the refractive index compared to oxygen, which is also a light element component. Therefore, it can be used for film thickness reduction to obtain the desired phase difference. Furthermore, the total content of light element components, including oxygen and nitrogen contained in the phase-shifting film 30, is preferably 50 atomic percent or more and 65 atomic percent or less. Furthermore, when oxygen is present in the phase-shifting film 30, the oxygen content is greater than 0 atomic% and less than 40 atomic%, which is preferred in terms of defect quality and drug resistance.

[0092] Furthermore, in addition to oxygen and nitrogen, the phase-shifting film 30 may contain other light element components such as carbon and helium in order to reduce film stress and control wet etching rate.

[0093] The phase-shifting film 30 can have a columnar structure. Particularly when the phase-shifting film 30 is composed of a silicon molybdenum oxide-based material, there is a tendency for a low etch rate; therefore, it is preferable to increase the etch rate of the phase-shifting film 30. This columnar structure can be confirmed by cross-sectional SEM observation of the phase-shifting film 30. That is, in the columnar structure of the present invention, the particles containing the transition metal silicon oxide compound, including the transition metal and silicon constituting the phase-shifting film 30, have a columnar particle structure that extends towards the film thickness direction of the phase-shifting film 30 (the direction of particle accumulation). It should be noted that in this application, a columnar particle is defined as a particle whose length in the film thickness direction is longer than its length in the direction perpendicular to the film thickness direction. That is, for the phase-shifting film 30, columnar particles extending towards the film thickness direction are formed within the surface of the transparent substrate 20. Furthermore, by adjusting the film formation conditions (sputtering pressure, etc.), the phase-shifting film 30 can form a sparse portion (hereinafter referred to as "sparse portion") with a relatively lower density compared to columnar particles. It should be noted that the phase-shifting film 30 can effectively suppress side etching during wet etching, further optimizing the pattern cross-sectional shape. As a preferred embodiment of the columnar structure of the phase-shifting film 30, the columnar particles extending in the film thickness direction are preferably formed irregularly in the film thickness direction. More preferably, the columnar particles of the phase-shifting film 30 have inconsistent lengths in the film thickness direction. Moreover, it is preferable that the sparse portion of the phase-shifting film 30 is formed continuously in the film thickness direction.

[0094] Preferably, the phase-shifting film 30 is a single-layer film or a laminated film composed of the same component. With such a phase-shifting film 30, interface and internal reflections within the film can be suppressed, and the cross-section of the pattern formed by wet etching can be easily controlled. Furthermore, no complex changes to the film formation conditions are required, thus simplifying the film formation process.

[0095] The phase-shifting film 30 can be formed by sputtering.

[0096] An etching mask 40 is disposed above the phase-shifting film 30 and is made of a material that has etching resistance (etching selectivity different from that of the phase-shifting film 30) relative to the etching solution used to etch the phase-shifting film 30. Furthermore, the etching mask 40 may have the kinetic energy to block the transmission of exposure light, and may also have the function of reducing the film surface reflectivity so that the film surface reflectivity of the phase-shifting film 30 relative to light incident from the phase-shifting film 30 side is less than 15% in the wavelength range of 313 nm to 436 nm. The etching mask 40 may be made of a chromium-based material containing chromium (Cr). More specifically, examples of chromium-based materials include chromium (Cr) or materials containing at least one of oxygen (O), nitrogen (N), and carbon (C) and chromium (Cr). Alternatively, materials containing at least one of oxygen (O), nitrogen (N), and carbon (C) and chromium (Cr), and further containing fluorine (F). For example, materials constituting the etching mask film 40 include Cr, CrO, CrN, CrF, CrCO, CrCN, CrON, CrCON, and CrCONF. Chromium-based materials are preferred because they exhibit high resistance to chemicals and excellent adhesion to the resist film.

[0097] The etched mask film 40 can be formed by sputtering.

[0098] When the etching mask film 40 has the function of blocking the transmission of exposure light, the optical concentration of the phase shift film 30 and the etching mask film 40 stacked in the phase is preferably 3 or more, more preferably 3.5 or more, and even more preferably 4 or more.

[0099] Optical concentration can be measured using a spectrophotometer or OD meter.

[0100] The etching mask film 40 can be composed of a single film with uniform composition, multiple films with different compositions, or a single film with continuously varying composition in the thickness direction, depending on its function.

[0101] It should be noted that, Figure 1 The phase shift mask substrate 10 shown has an etched mask film 40 on the phase shift film 30, but the present invention can also be applied to a phase shift mask substrate having an etched mask film 40 on the phase shift film 30 and a resist film on the etched mask film 40.

[0102] Next, the manufacturing method of the phase shift mask base plate 10 of embodiments 1 and 2 will be described. Figure 1 The phase-shifting mask substrate 10 shown can be manufactured by performing the following phase-shifting film formation process and etching mask film formation process. Figure 2 The phase-shifting mask base plate 10 shown can be manufactured by a phase-shifting film forming process.

[0103] The following is a detailed explanation of each process.

[0104] 1. Phase-shifting film formation process

[0105] First, prepare a transparent substrate 20. The transparent substrate 20 only needs to be transparent to the exposure light, and can be made of any glass material such as synthetic quartz glass, quartz glass, aluminosilicate glass, soda-lime glass, low thermal expansion glass (SiO2-TiO2 glass, etc.).

[0106] Next, a phase-shifting film 30 is formed on the transparent substrate 20 by sputtering.

[0107] The formation of the phase-shifting film 30 can be achieved, for example, when the main component of the material constituting the phase-shifting film 30 is ZrMoSi, by using a ZrMoSi target containing molybdenum (Mo), zirconium (Zr), and silicon (Si), or a ZrMoSiO target, ZrMoSiN target, or ZrMoSiON target containing molybdenum (Mo), zirconium (Zr), silicon (Si), oxygen (O), and / or nitrogen (N). Sputtering can be performed, for example, in a sputtering gas atmosphere containing at least one inert gas selected from the group consisting of helium, neon, argon, krypton, and xenon, or in a sputtering gas atmosphere containing a mixture of the aforementioned inert gas and an active gas selected from the group consisting of oxygen, nitrogen, carbon dioxide, nitric oxide, and nitrogen dioxide, and containing at least nitrogen.

[0108] The composition and thickness of the phase-shift film 30 are adjusted to give it the aforementioned optical properties such as phase difference, transmittance, and reflectance. The composition of the phase-shift film 30 can be controlled by the proportions of elements constituting the sputtering target (e.g., the content of Mo, Zr, and Si), the composition of the sputtering gas, and its flow rate. The thickness of the phase-shift film 30 can be controlled by the sputtering power and sputtering time. Furthermore, the phase-shift film 30 is preferably formed using a continuous sputtering apparatus. When the sputtering apparatus is a continuous sputtering apparatus, the thickness of the phase-shift film 30 can be controlled by the substrate transport speed.

[0109] When performing multiple film-forming processes on the phase-shifting film 30, the sputtering power applied to the sputtering target can be reduced.

[0110] Thus, the phase shift mask substrate 10 of Embodiment 2 can be obtained. In the manufacturing of the phase shift mask substrate 10 of Embodiment 1, the following etching mask film formation process is further performed.

[0111] 2. Etching mask film formation process

[0112] After surface treatment to adjust the oxidation state of the phase shift film 30 as needed, an etching mask film 40 is formed on the phase shift film 30 by sputtering. Preferably, the etching mask film 40 is formed using a continuous sputtering apparatus. When the sputtering apparatus is a continuous sputtering apparatus, the thickness of the etching mask film 40 can be controlled by the transport speed of the transparent substrate 20.

[0113] The etching mask film 40 can be formed, for example, by using a sputtering target containing chromium or chromium compounds (chromium oxide, chromium nitride, chromium carbide, chromium oxynitride, chromium oxynitride, etc.) when the etching mask film 40 is made of a chromium-based material. Sputtering can be performed, for example, in a sputtering gas atmosphere containing at least one inert gas selected from the group consisting of helium, neon, argon, krypton, and xenon, or in a sputtering gas atmosphere containing an inert gas selected from the group consisting of at least one inert gas and an active gas selected from the group consisting of oxygen, nitrogen, nitric oxide, nitrogen dioxide, carbon dioxide, hydrocarbon gases, and fluorine gases. Examples of hydrocarbon gases include methane, butane, propane, and phenylethane.

[0114] When the etching mask film 40 is composed of a single film with uniform composition, the above-described film formation step can be performed once without changing the composition and flow rate of the sputtering gas. When the etching mask film 40 is composed of multiple films with different compositions, the above-described film formation step can be performed multiple times by changing the composition and flow rate of the sputtering gas in each film formation step. When the etching mask film 40 is composed of a single film with a composition that continuously varies in the thickness direction, the above-described film formation step is performed once by changing the composition and flow rate of the sputtering gas as the time of the film formation step elapses.

[0115] The phase shift mask base plate 10 of Embodiment 1 is obtained in this way.

[0116] It should be noted that, Figure 1 The phase-shift mask substrate 10 shown has an etching mask film 40 on the phase-shift film 30, therefore, an etching mask film forming process is performed during the manufacture of the phase-shift mask substrate 10. Furthermore, when manufacturing a phase-shift mask substrate having an etching mask film 40 on the phase-shift film 30 and a resist film on the etching mask film 40, a resist film is formed on the etching mask film 40 after the etching mask film forming process. Furthermore, in Figure 2 In the phase shift mask base plate 10 shown, when manufacturing a phase shift mask base plate having a resist film on the phase shift film 30, the resist film is formed after the phase shift film forming process.

[0117] Even when the phase-shifting film exhibits film thickness fluctuations, the phase-shifting mask substrate 10 of embodiments 1 and 2 can suppress fluctuations in transmittance relative to the representative wavelength of the exposure light, thereby achieving the desired high transmittance and enabling good pattern transfer.

[0118] Implementation methods 3 and 4

[0119] In embodiments 3 and 4, the manufacturing method of the phase shift mask will be described.

[0120] Figure 3 (a) to (e) are schematic diagrams illustrating the manufacturing method of the phase shift mask in Embodiment 3. Figure 4 This is a schematic diagram illustrating the manufacturing method of the phase shift mask in Embodiment 4.

[0121] Figure 3 The method for manufacturing the phase shift mask shown in (a) to (e) is to use Figure 1 The method for manufacturing a phase shift mask using the phase shift mask substrate 10 shown includes: a step of forming a resist film on an etch mask film 40 of the phase shift mask substrate 10; a step of drawing and developing a desired pattern on the resist film to form a resist film pattern 50 (first resist film pattern forming step); a step of wet etching the etch mask film 40 using the resist film pattern 50 as a mask to form an etch mask film pattern 40a on the phase shift film 30 (first etch mask film pattern forming step); and a step of wet etching the phase shift film 30 using the etch mask film pattern 40a as a mask to form a phase shift film pattern (patterned phase shift film) 30a on a transparent substrate 20 (phase shift film pattern forming step). Furthermore, it further includes a second resist film pattern forming step and a second etch mask film pattern forming step.

[0122] Figure 4 The method for manufacturing the phase shift mask shown in (a) to (c) is to use Figure 2 The method for manufacturing a phase shift mask using the phase shift mask substrate 10 shown includes: a step of forming a resist film on the phase shift mask substrate 10; a step of drawing and developing a desired pattern on the resist film to form a resist film pattern 50 (first resist film pattern forming step); and a step of wet etching the phase shift film 30 using the resist film pattern 50 as a mask to form a phase shift film pattern 30a on a transparent substrate 20 (phase shift film pattern forming step).

[0123] The manufacturing process of the phase shift mask in embodiments 3 and 4 will be described in detail below.

[0124] Manufacturing process of phase shift mask in embodiment 3

[0125] 1. First resist film pattern formation process

[0126] In the first resist film patterning step, a resist film is first formed on the etching mask film 40 of the phase shift mask substrate 10 of Embodiment 1. There are no particular limitations on the resist film material used. For example, it can be photosensitive to laser light with any wavelength selected from the wavelength range of 350 nm to 436 nm (described later). Furthermore, the resist film can be either a forward-facing type or a reverse-facing type.

[0127] Then, a laser with an arbitrary wavelength selectable from 350 nm to 436 nm is used to draw the desired pattern on the resist film. The pattern drawn on the resist film can be a pattern formed on the phase shift film 30. Examples of patterns drawn on the resist film include line and space patterns, and hole patterns.

[0128] Then, the resist film is developed using the specified developer, such as... Figure 3 As shown in (a), a first resist film pattern 50 is formed on the etch mask film 40.

[0129] 2. First etching mask pattern formation process

[0130] In the first etching mask pattern formation step, the etching mask 40 is first etched using the first resist film pattern 50 as a mask to form the first etching mask pattern 40a. The etching mask 40 can be formed from a chromium-based material containing chromium (Cr). The etching solution used to etch the etching mask 40 can selectively etch the etching mask 40, without particular limitations. Specifically, etching solutions containing cerium ammonium nitrate and perchloric acid can be used as examples.

[0131] Afterwards, use a resist stripping solution or through ashing, such as... Figure 3 As shown in (b), the first resist film pattern 50 is peeled off. Depending on the circumstances, the subsequent phase-shift film patterning process may be performed without peeling off the first resist film pattern 50.

[0132] 3. Phase-shifting film pattern formation process

[0133] In the first phase-shifting film pattern formation process, the phase-shifting film 30 is wet-etched using the first etching mask film pattern 40a as a mask, such as... Figure 3 As shown in (c), a phase-shifting film pattern 30a is formed. Examples of phase-shifting film patterns 30a include line and spatial patterns and hole patterns. The etchant used to etch the phase-shifting film 30 is not particularly limited as long as it selectively etches the phase-shifting film 30. Examples include etchants containing ammonium fluoride, phosphoric acid, and hydrogen peroxide, and etchants containing ammonium bifluoride and hydrogen peroxide.

[0134] To ensure a good cross-sectional shape for the phase-shifting film pattern 30a, wet etching is preferably performed for a time longer than the time until the transparent substrate 20 is exposed (the over-etching time). Considering the impact on the transparent substrate 20, the over-etching time is preferably a time that is 10 to 20% of the appropriate etching time added to the appropriate etching time.

[0135] 4. Second resist film pattern formation process

[0136] In the second resist film patterning step, firstly, a resist film covering the first etch mask film pattern 40a is formed. The resist film material used is not particularly limited. For example, it can be photosensitive to any wavelength selected relative to a laser with a wavelength range of 350 nm to 436 nm (described later). Furthermore, the resist film can be either a forward-facing or reverse-facing type.

[0137] Next, a laser with an arbitrary wavelength selectable from 350 nm to 436 nm is used to draw the desired pattern on the resist film. The pattern drawn on the resist film may be a light-shielding strip pattern that blocks light from the outer periphery of the patterned area on the phase-shift film 30, or a light-shielding strip pattern that blocks light from the central portion of the phase-shift film pattern. It should be noted that, depending on the transmittance of the phase-shift film 30 relative to the exposure light, there may also be cases where the pattern drawn on the resist film does not block light from the central portion of the phase-shift film pattern 30a.

[0138] Then, the resist film is developed using the specified developer, such as... Figure 3 As shown in (d), a second resist film pattern 60 is formed on the first etch mask film pattern 40a.

[0139] 5. Second etching mask pattern formation process

[0140] In the second etching mask film pattern formation process, the first etching mask film pattern 40a is etched using the second resist film pattern 60 as a mask, such as... Figure 3 As shown in (e), a second etch mask pattern 40b is formed. The first etch mask pattern 40a can be formed from a chromium-based material containing chromium (Cr). The etchant used to etch the first etch mask pattern 40a can selectively etch the first etch mask pattern 40a, and there are no particular limitations. For example, an etchant containing cerium ammonium nitrate and perchloric acid can be used.

[0141] Then, the second resist film pattern 60 is peeled off using a resist stripping solution or by ashing.

[0142] In this way, a phase shift mask of 100 can be obtained.

[0143] It should be noted that the above description describes the case where the etching mask film 40 has the function of blocking the transmission of exposure light. However, when the etching mask film 40 only has the function of a hard mask when etching the phase shift film 30, in the above description, the second resist film pattern formation process and the second etching mask film pattern formation process are not performed. After the phase shift film pattern formation process, the first etching mask film pattern 40a is peeled off to form the phase shift mask 100.

[0144] According to the manufacturing method of the phase shift mask in Embodiment 3, since the phase shift mask base plate of Embodiment 1 is used, the etching time can be shortened, and a phase shift film pattern with good cross-sectional shape and chemical resistance can be formed. Therefore, it is possible to manufacture a phase shift mask that can transfer high-precision phase shift film patterns with good accuracy. The phase shift mask manufactured in this way can handle the miniaturization of line and spatial patterns, hole patterns, and dot patterns.

[0145] Manufacturing process of phase shift mask in embodiment 4

[0146] 1. Resist film pattern formation process

[0147] In the resist film patterning process, firstly, a resist film is formed on the phase shift film 30 of the phase shift mask substrate 10 in Embodiment 2. The resist film material used is the same as that described in Embodiment 3. It should be noted that before forming the resist film as needed, the phase shift film 30 may be surface modified to ensure good adhesion with the phase shift film 30. As above, after forming the resist film, a laser with an arbitrary wavelength selected from the wavelength range of 350 nm to 436 nm is used to draw the desired pattern on the resist film. Then, the resist film is developed with a prescribed developer, such as... Figure 4 As shown in (a), a resist film pattern 50 is formed on the phase shift film 30.

[0148] 2. Phase-shifting film pattern formation process

[0149] In the phase-shifting film patterning process, the phase-shifting film 30 is etched using the resist film pattern 50 as a mask, such as... Figure 4 As shown in (b), a phase-shifting film pattern 30a is formed. The etching solution and over-etching time used to etch the phase-shifting film pattern 30a and the phase-shifting film 30 are the same as those described in Embodiment 3.

[0150] Subsequently, the resist film pattern 50 is peeled off using a resist stripping solution or by ashing. Figure 4 (c)).

[0151] Phase shift mask 100 is obtained in this way.

[0152] According to the manufacturing method of the phase-shifting mask in Embodiment 4, since the phase-shifting mask base plate of Embodiment 2 is used, the reduction in transmittance of the transparent substrate caused by the damage to the substrate by the wet etching solution is avoided, the etching time can be shortened, and a phase-shifting film pattern with good cross-sectional shape, good chemical resistance, and suppressed back-side reflectivity can be formed. Therefore, a phase-shifting mask that can transfer high-precision phase-shifting film patterns with good accuracy can be manufactured. The phase-shifting mask manufactured in this way can handle the miniaturization of line and spatial patterns, hole patterns, and dot patterns.

[0153] Implementation method 5.

[0154] In Embodiment 5, a method for manufacturing a display device will be described. The display device can be manufactured by performing a process of placing a phase shift mask 100 manufactured using the phase shift mask substrate 10 or a phase shift mask 100 manufactured by the method described above on the mask stage of an exposure apparatus (mask placement process) and a process of exposing and transferring a transfer pattern onto a resist film on the display device (exposure process). This transfer pattern may only include a phase shift film pattern, or it may further include a pattern formed by patterning other optical films (optical film pattern). For example, the second etching mask film pattern described above can be used as an example of other optical film patterns. In this case, the overlapping area of ​​the phase shift film pattern and the etching mask film pattern can be made into a light-shielding zone.

[0155] The following is a detailed explanation of each process.

[0156] 1. Placement process

[0157] In the placement process, the phase-shifting mask manufactured in Embodiment 3 is placed on the mask stage of the exposure apparatus. Here, the phase-shifting mask is positioned opposite the resist film formed on the display device substrate via the projection optics system of the exposure apparatus.

[0158] 2. Pattern transfer process

[0159] In the pattern transfer process, exposure light is irradiated onto the phase-shift mask 100 to transfer the phase-shift film pattern onto the resist film formed on the display device substrate. The exposure light is a composite light including multiple wavelengths selected from the wavelength range of 313 nm to 436 nm, and a monochromatic light selected by filtering the wavelength range of 313 nm to 436 nm. For example, the exposure light is a composite light including i-lines, h-lines, and g-lines, and a monochromatic light including i-lines. If composite light is used as the exposure light, the exposure light intensity can be increased, thereby increasing the throughput and reducing the manufacturing cost of the display device.

[0160] According to the manufacturing method of the display device of this embodiment 3, it is possible to manufacture a high-definition display device with high definition, fine line and spatial patterns, hole patterns and dot patterns.

[0161] [Example]

[0162] Example 1

[0163] A. Phase shift mask base plate

[0164] In order to manufacture the phase shift mask base plate of Example 1, a synthetic quartz glass substrate is first prepared as a transparent substrate 20.

[0165] Next, the synthetic quartz glass substrate is placed on a tray (not shown) with its main surface facing downwards and then fed into the chamber of the continuous sputtering apparatus.

[0166] To form a phase-shifting film 30 on the main surface of the transparent substrate 20, a mixed gas consisting of argon (Ar) and nitrogen (N2) is first introduced into the first chamber. Then, using a ZrMoSi target composed of Mo, Zr, and Si in a ratio of Mo:Zr:Si = 4:16:80, a ZrMoSiN phase-shifting film 30 containing molybdenum, zirconium, silicon, and nitrogen is formed on the main surface of the transparent substrate 20 by reactive sputtering to achieve a film thickness of 153 nm.

[0167] Next, the transparent substrate 20 with the phase-shifting film 30 is sent into the third chamber, and a mixture of argon (Ar) and nitrogen (N2) is introduced into the third chamber. By reactive sputtering, a chromium nitride (CrN) containing chromium and nitrogen is formed on the phase-shifting film 30.

[0168] Next, with the fourth chamber at a specified vacuum level, a mixture of argon (Ar) and methane is introduced, and a chromium carbide (CrC) containing chromium and carbon is formed on CrN by reactive sputtering.

[0169] Finally, with the fifth chamber at a specified vacuum level, a mixture of argon (Ar) and methane and a mixture of nitrogen (N2) and oxygen (O2) are introduced, and a chromium carbon oxynitride (CrCON) containing chromium, carbon, oxygen and nitrogen is formed on CrC by reactive sputtering.

[0170] Through the above methods, an etching mask film 40 with a stacked structure of CrN layer, CrC layer and CrCON layer is formed on the phase shift film 30.

[0171] In this way, a phase shift mask substrate 10 is obtained on a transparent substrate 20 having a phase shift film 30 and an etching mask film 40 formed thereon.

[0172] The refractive index and attenuation coefficient of the phase shift film 30 of the obtained phase shift mask substrate 10 were measured using a phase shift film substrate (dummy substrate) on the main surface of a synthetic quartz glass substrate on which the phase shift film 30 is formed, using a spectroelliptic meter (JAWoollam M-2000D).

[0173] As a result, the refractive index n of the ZrMoSiN phase-shifted film is 2.35 (wavelength 405 nm), satisfying the condition of ≥2.20 and ≤2.57. Furthermore, the attenuation coefficient k is 0.11 (wavelength 405 nm), satisfying the condition of ≥0.10 and ≤0.25.

[0174] Furthermore, the transmittance and phase difference of the phase-shifting film 30 on the obtained phase-shifting mask substrate 10 were measured using an MPM-100 manufactured by Lasertec. The transmittance and phase difference of the phase-shifting film 30 were measured using a phase-shifting film substrate (dummy substrate) on the main surface of a synthetic quartz glass substrate on the same tray as described above. The transmittance and phase difference of the phase-shifting film 30 were measured by removing the phase-shifting film substrate (dummy substrate) from the chamber before forming the etching mask film 40. The results showed a transmittance of 50% (wavelength: 405 nm) and a phase difference of 180° (wavelength: 405 nm).

[0175] Furthermore, through simulation analysis of the back reflectance under conditions where the film thickness of the phase-shifting film fluctuates, when the film thickness fluctuates within a range below 30 nm, the difference between the maximum and minimum reflectance values ​​at the representative wavelength is 18% (18 points), exceeding 10%. Similarly, through simulation analysis of transmittance, when the film thickness fluctuates within a range below 30 nm, the difference between the maximum and minimum transmittance values ​​at the representative wavelength (transmittance fluctuation value) is 4% (4 points), which is 8% compared to the transmittance (50%) at a wavelength of 405 nm with a film thickness of 153 nm (before the film thickness fluctuation), falling below 20%.

[0176] Thus, for the phase-shift mask substrate 10 in Example 1, even if the phase-shift film experiences thickness fluctuations, it can suppress fluctuations in transmittance relative to the representative wavelength of the exposure light and achieve the desired high transmittance, and can perform good pattern transfer. Furthermore, the phase-shift film of Example 1 has the above-mentioned optical properties at a thickness of 153 nm, which is smaller than the film thickness of 180 nm, and can be used for fine pattern formation.

[0177] B. Phase shift masks and their manufacturing methods

[0178] In order to manufacture a phase shift mask 100 using the phase shift mask substrate 10 manufactured as described above, firstly, a photoresist film is coated on the etched mask film 40 of the phase shift mask substrate 10 using a photoresist coating device.

[0179] Afterwards, a photoresist film is formed through heating and cooling processes.

[0180] Subsequently, a laser drawing device is used to draw the photoresist film. After development and cleaning processes, a photoresist film pattern with a hole pattern of 1.5 μm is formed on the etched mask film.

[0181] Subsequently, using the resist film pattern as a mask, the etching mask film is wet-etched using a chromium etching solution containing cerium ammonium nitrate and perchloric acid to form the first etching mask film pattern 40a.

[0182] Subsequently, using the first etch mask film pattern 40a as a mask, the phase shift film 30 is wet-etched using an etchant diluted with pure water through a mixed solution of ammonium bifluoride and hydrogen peroxide to form the phase shift film pattern 30a. This wet etching is performed with an over-etching time of 10% to ensure that the cross-sectional shape is vertical and to form the required fine pattern.

[0183] Next, the resist film pattern is peeled off.

[0184] Subsequently, a photoresist film is coated using a photoresist coating apparatus to cover the first etched mask pattern 40a.

[0185] Afterwards, a photoresist film is formed through heating and cooling processes.

[0186] Subsequently, a photoresist film is drawn using a laser drawing device, and after development and cleaning processes, a second photoresist film pattern 60 for forming a light-shielding band is formed on the first etched mask film pattern 40a.

[0187] Subsequently, using the second resist film pattern 60 as a mask, a chromium etching solution containing cerium ammonium nitrate and perchloric acid is used to wet-etch the first etch mask film pattern 40a formed in the transfer pattern formation area.

[0188] Then, the second resist film pattern 60 is peeled off.

[0189] In this way, a phase-shifting mask 100 is obtained, which has a phase-shifting film pattern 30a with an aperture of 1.5 μm formed in the transfer pattern forming area and a light-shielding band formed on the transparent substrate 20 by the stacked structure of the phase-shifting film pattern 30a and the etched mask film pattern 40b.

[0190] The cross-section of the obtained phase-shifting mask was observed using a scanning electron microscope. In the cross-section of the phase-shifting mask in Example 1, the angle between the edge of the phase-shifting film pattern 30a and the main surface of the transparent substrate 20 is 75° or more, resulting in a nearly vertical cross-sectional shape. The phase-shifting film pattern 30a formed on the phase-shifting mask in Example 1 has a cross-sectional shape that can fully exert the phase-shifting effect. Furthermore, the surface of the exposed transparent substrate 20 after removing the phase-shifting film 30 is smooth, and no reduction in transmittance due to surface roughness of the transparent substrate 20 was observed. Therefore, a phase-shifting mask with excellent phase-shifting effect can be obtained in exposure light containing light in the wavelength range of 313 nm or more and 500 nm or less, and more specifically, in exposure light containing composite light containing at least one of the i-line, h-line, and g-line.

[0191] Therefore, when the phase-shifting mask in Example 1 is placed on the mask stage of the exposure device to expose and transfer the resist film on the display device, it is also possible to transfer fine patterns smaller than 2.0 μm with high precision.

[0192] Example 2

[0193] A. Phase shift mask base plate

[0194] In Example 2, except for the phase-shifting film 30, a simulation of manufacturing the phase-shifting mask substrate 10 and the phase-shifting mask 100 was performed using the same construction and method as in Example 1. In Example 2, a phase-shifting film with a ZrMoSiN-type material layer was selected.

[0195] Regarding the optical properties of the ZrMoSiN phase-shifting film, the refractive index n is 2.45 (wavelength 405 nm), satisfying the condition of ≥2.20 and ≤2.57. Furthermore, the attenuation coefficient k is 0.11 (wavelength 405 nm), satisfying the condition of ≥0.10 and ≤0.25. Moreover, through simulation of the phase-shifting film 30, with a film thickness of 143 nm, the transmittance is 49% (wavelength: 405 nm), and the phase difference is 180° (wavelength: 405 nm).

[0196] Furthermore, by simulating and analyzing the back reflectance under conditions of film thickness fluctuation in this phase-shifting film, when the film thickness fluctuates within a range below 30 nm, the difference between the maximum and minimum back reflectance at the representative wavelength is 20%, reaching over 10%. Similarly, by simulating and analyzing the transmittance, when the film thickness fluctuates within a range below 30 nm, the difference between the maximum and minimum transmittance at the representative wavelength (transmittance fluctuation value) is 6%, which is 12% compared to the transmittance (49%) at a wavelength of 405 nm with a film thickness of 143 nm (before the film thickness fluctuation), reaching below 20%.

[0197] Thus, even when the phase-shifting film thickness fluctuates, the phase-shifting mask substrate 10 in Example 2 can suppress fluctuations in transmittance relative to the representative wavelength of the exposure light and achieve the desired high transmittance, and can perform good pattern transfer. Furthermore, the phase-shifting film of Example 2, with a thickness of 143 nm (less than 180 nm), possesses the aforementioned optical properties, making it suitable for fine pattern formation. That is, the phase-shifting film pattern 30a formed on the phase-shifting mask obtained by patterning the phase-shifting film of Example 2 has a fine size (width) capable of fully utilizing the phase-shifting effect. Therefore, in Example 2, a phase-shifting mask with excellent phase-shifting effect can be obtained in exposure light including light with wavelengths of 313 nm and above and 500 nm and, more specifically, in exposure light including at least one of the i-line, h-line, and g-line composite light.

[0198] Therefore, when the phase-shift mask of Example 2 is placed on the mask stage of the exposure apparatus to expose and transfer the resist film on the display device, it is possible to transfer fine patterns smaller than 2.0 μm with high precision.

[0199] Comparative Example 1

[0200] In Comparative Example 1, simulations were performed using the same construction and method as in Example 1, except for the phase-shifting film 30, to manufacture the phase-shifting mask substrate 10 and the phase-shifting mask 100. In Comparative Example 1, a phase-shifting film made of a ZrSiN-type material was selected. This ZrSiN-type material phase-shifting film can be obtained by reactive sputtering, for example, by using a ZrSi target that adjusts the ratio of Zr to Si to obtain the desired refractive index n and attenuation coefficient k, as a sputtering target used in Example 1 above, to form a ZrSiN phase-shifting film 30 containing zirconium, silicon, and nitrogen on the main surface of the transparent substrate 20.

[0201] Regarding the optical properties of the ZrSiN phase-shifting film in Comparative Example 1, the refractive index n is 2.65 (wavelength 405 nm), which does not satisfy the condition of 2.20 or more and 2.57 or less. Furthermore, the attenuation coefficient k is 0.09 (wavelength 405 nm), which does not satisfy the condition of 0.10 or more and 0.25 or less.

[0202] Furthermore, by simulating the phase shift film 30 of the phase shift mask base plate 10, when the film thickness is 130 nm, the transmittance is 50% (wavelength: 405 nm) and the phase difference is 180° (wavelength: 405 nm).

[0203] Furthermore, by simulating and analyzing the back reflectance under conditions where the film thickness of the phase-shifting film fluctuates, when the film thickness fluctuates within a range below 30 nm, the difference between the maximum and minimum back reflectance at the representative wavelength is 23%, exceeding 10%. However, by similarly simulating and analyzing the transmittance, when the film thickness fluctuates within a range below 30 nm, the difference between the maximum and minimum transmittance at the representative wavelength (transmittance fluctuation value) is 11%, which is 22% compared to the transmittance (50%) at a wavelength of 405 nm with a film thickness of 130 nm (before the film thickness fluctuation), not reaching below 20%.

[0204] Thus, in Comparative Example 1, the phase-shifting mask substrate 10 and the phase-shifting mask 100 manufactured using the substrate cannot suppress the fluctuation of transmittance relative to the representative wavelength of the exposed light when the phase-shifting film thickness fluctuates, resulting in a deviation from the desired transmittance. Furthermore, while the phase-shifting film in Comparative Example 1 exhibits high transmittance, its back-side reflectance at a thickness of 130 nm is relatively high at 24%. Therefore, the phase-shifting mask substrate 10 and the phase-shifting mask 100 in Comparative Example 1 cannot perform the desired phase-shifting function and cannot achieve satisfactory pattern transfer.

[0205] Comparative Example 2

[0206] In Comparative Example 2, simulations were performed using the same construction and method as in Example 1, except for the phase-shifting film 30, to manufacture the phase-shifting mask substrate 10 and the phase-shifting mask 100. In Comparative Example 2, a phase-shifting film made of a MoSiN-type material was selected. This phase-shifting film made of a MoSiN-type material can be obtained by, for example, by using a MoSi target with a desired refractive index n and attenuation coefficient k, which is used as a sputtering target for forming the phase-shifting film in Example 1 above, and by reactive sputtering to form a MoSiN phase-shifting film 30 containing molybdenum, silicon, and nitrogen on the main surface of the transparent substrate 20.

[0207] Regarding the optical properties of the MoSiN phase-shifting film in Comparative Example 2, the refractive index n is 2.30 (wavelength 405 nm), satisfying the condition of 2.20 or more and 2.57 or less. On the other hand, the attenuation coefficient k is 0.28 (wavelength 405 nm), which does not satisfy the condition of 0.10 or more and 0.25 or less.

[0208] Furthermore, by simulating the phase shift film 30 of the phase shift mask base plate 10, the transmittance was 22% (wavelength: 405nm) and the phase difference was 180° (wavelength: 405nm) when the film thickness was 159nm.

[0209] Furthermore, through simulation analysis of the back reflectance under varying film thickness of the phase-shifting film, when the film thickness fluctuates within a range below 30 nm, the difference between the maximum and minimum back reflectance at the representative wavelength is 9%, which is less than 10%. Similarly, through simulation analysis of transmittance, when the film thickness fluctuates within a range below 30 nm, the difference between the maximum and minimum transmittance at the representative wavelength (transmittance fluctuation value) is 5%, which is 23% compared to the transmittance at 405 nm (22%) before the film thickness fluctuation (159 nm), and is less than 20%.

[0210] In this way, when the phase-shifting mask base plate 10 of Comparative Example 2 and the phase-shifting mask 100 manufactured using that mask base plate experience film thickness fluctuations, the transmittance fluctuations relative to the representative wavelength of the exposed light cannot be suppressed, resulting in a deviation from the desired transmittance. Therefore, the phase-shifting mask base plate 10 and the phase-shifting mask 100 of Comparative Example 2 cannot perform the desired phase-shifting function and cannot be considered to have achieved good pattern transfer.

[0211] Reference Example 1

[0212] In Reference Example 1, the phase-shifting film 30 was removed, and the fabrication of the phase-shifting mask substrate 10 and the phase-shifting mask 100 was simulated using the same construction and method as in Example 1. In Reference Example 1, a phase-shifting film made of a MoSiN-type material was selected. This MoSiN-type material phase-shifting film was used, for example, as a sputtering target during the film formation process in Example 1 above. A MoSi target with the desired refractive index n and attenuation coefficient k obtained by adjusting the ratio of Mo to Si was used. The phase-shifting film 30 containing molybdenum, silicon, and nitrogen was formed on the main surface of the transparent substrate 20 by reactive sputtering.

[0213] Regarding the optical properties of the phase-shifting film made of MoSiN-type materials in Reference Example 1, the refractive index n is 2.12 (wavelength 405 nm), which does not satisfy the condition of 2.20 or more and 2.57 or less. Furthermore, the attenuation coefficient k is 0.11 (wavelength 405 nm), which satisfies the condition of 0.10 or more and 0.25 or less.

[0214] Furthermore, the phase shift film 30 of the phase shift mask base plate 10, through simulation, has a transmittance of 50% (wavelength: 405nm) and a phase difference of 180° (wavelength: 405nm) when the film thickness is 182nm.

[0215] Furthermore, by simulating the back reflectance under conditions of film thickness fluctuation of the phase-shifting film, when the film thickness fluctuates within a range of less than 30 nm, the difference between the maximum and minimum back reflectance at the representative wavelength is 9%, which is less than 10%. Similarly, by simulating the transmittance, when the film thickness fluctuates within a range of less than 30 nm, the difference between the maximum and minimum transmittance at the representative wavelength (transmittance fluctuation value) is 3%, which is 6% compared to the transmittance (50%) at 405 nm with a film thickness of 182 nm (before the film thickness fluctuation), reaching less than 20%. However, the phase-shifting film of Reference Example 1 has a low refractive index, so in order to achieve a phase shift function of approximately 180° relative to the wavelength of 405 nm, it is necessary to increase the film thickness to 182 nm. That is, the film thickness of the phase-shifting film of Reference Example 1 is greater than 180 nm, which may result in a longer etching time compared to the embodiment. In this situation, the transparent substrate is prone to damage, and the transmittance of the exposed area on the main surface of the transparent substrate is more likely to fail to meet the desired value. Furthermore, when isotropic etching, i.e., wet etching, is used to form spatial or hole patterns, etching also occurs in the direction perpendicular to the film thickness direction before the main surface of the transparent substrate is exposed. Therefore, if the film thickness is large, it is difficult to form fine patterns. The phase-shifting film of Reference Example 1 is insufficient to form fine patterns.

[0216] The materials used in the phase-shifting films in the above embodiments, comparative examples, and reference examples are merely examples. Therefore, without departing from the scope of the present invention, the materials of the phase-shifting films are not limited to those used in the above embodiments. Furthermore, the present invention does not exclude the materials used in the comparative examples and reference examples. Any material can achieve the same effects as the above embodiments, as long as it meets the constituent requirements of the present invention.

[0217] Explanation of reference numerals in the attached figures

[0218] 10…Phase-shifting mask substrate, 20…Transparent substrate, 30…Phase-shifting film, 30a…Phase-shifting film pattern (a phase-shifting film with a pattern), 40…Etching mask film, 40a…First etched mask film pattern, 40b…Second etched mask film pattern, 50…First resist film pattern, 60…Second resist film pattern, 100…Phase-shifting mask.

Claims

1. A phase-shifting mask substrate having a phase-shifting film on a transparent substrate, characterized in that, The phase-shifting film has a transmittance of 30% or more and 80% or less at a wavelength of 405 nm, a phase shift of 160° or more and 200° or less, an attenuation coefficient k of 0.11 or more and 0.20 or less, and a refractive index n of 2.20 or more and 2.57 or less. The phase-shifting film has a thickness of 130 nm or more and 180 nm or less. The phase-shifting membrane is a single-layer membrane. The wavelength of 405 nm, in the relationship between the surface reflectance and wavelength of the phase-shifting film, lies between the valley of the surface reflectance on the adjacent short wavelength side and the peak of the surface reflectance on the adjacent long wavelength side. The phase-shifting film contains transition metals, silicon, and light elements, with the total content of light elements, including oxygen and nitrogen, being between 50 atomic% and 65 atomic%. The transition metal is one or more elements selected from molybdenum, zirconium, tantalum, tungsten, and titanium. For the phase-shifting film, when the transmittance fluctuation value is the difference between the maximum and minimum transmittance values ​​at a wavelength of 405 nm when the film thickness fluctuates within a range of less than 30 nm, the ratio of the transmittance fluctuation value to the transmittance at a wavelength of 405 nm before the film thickness fluctuates is less than 20%.

2. The phase-shifting mask base plate according to claim 1, characterized in that, For the phase-shifting film, when the film thickness fluctuates within the range of less than 30 nm, the difference between the maximum and minimum values ​​of the back reflectance relative to the wavelength of 405 nm is more than 10%.

3. The phase-shifting mask base plate according to claim 1, characterized in that, The phase-shifting film has an etching mask that has a different etching selectivity relative to the phase-shifting film.

4. A method for manufacturing a phase-shifting mask, characterized in that, have: The process of preparing the phase-shifting mask base plate as described in claim 1 or 2; The process of forming a resist film on the phase-shifting film, performing wet etching on the phase-shifting film using the resist film pattern formed from the resist film as a mask, and forming a phase-shifting film pattern on the transparent substrate.

5. A method for manufacturing a phase-shifting mask, characterized in that, have: The process of preparing the phase shift mask base plate as described in claim 3; The process of forming a resist film on the etching mask film, performing wet etching on the etching mask film using the resist film pattern formed from the resist film as a mask, and forming an etching mask film pattern on the phase shift film; The process of forming a phase-shifting film pattern on a transparent substrate by wet etching the phase-shifting film using the etched mask film pattern as a mask.

6. A phase-shifting mask having a patterned phase-shifting film on a transparent substrate, characterized in that, The phase-shifting film has a transmittance of 30% or more and 80% or less at a wavelength of 405 nm, a phase shift of 160° or more and 200° or less, an attenuation coefficient k of 0.11 or more and 0.20 or less, and a refractive index n of 2.20 or more and 2.57 or less. The phase-shifting film has a thickness of 130 nm or more and 180 nm or less. The phase-shifting membrane is a single-layer membrane. The wavelength of 405 nm, in the relationship between the surface reflectance and wavelength of the phase-shifting film, lies between the valley of the surface reflectance on the adjacent short wavelength side and the peak of the surface reflectance on the adjacent long wavelength side. The phase-shifting film contains transition metals, silicon, and light elements, with the total content of light elements, including oxygen and nitrogen, being between 50 atomic% and 65 atomic%. The transition metal is one or more elements selected from molybdenum, zirconium, tantalum, tungsten, and titanium. For the phase-shifting film, when the transmittance fluctuation value is the difference between the maximum and minimum transmittance values ​​at a wavelength of 405 nm when the film thickness fluctuates within a range of less than 30 nm, the ratio of the transmittance fluctuation value to the transmittance at a wavelength of 405 nm before the film thickness fluctuates is less than 20%.

7. The phase-shifting mask according to claim 6, characterized in that, For the phase-shifting film, when the film thickness fluctuates within the range of less than 30 nm, the difference between the maximum and minimum values ​​of the back reflectance relative to the wavelength of 405 nm is more than 10%.

8. A method for manufacturing a display device, characterized in that, The device includes an exposure process in which a phase shift mask obtained by the manufacturing method of the phase shift mask according to claim 4 or 5, or a phase shift mask according to claim 6 or 7, is placed on the mask stage of the exposure apparatus, and a transfer pattern formed on the phase shift mask is exposed and transferred to a resist formed on a display device substrate.

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