Method for manufacturing photomask, photomask, and method for manufacturing device for display

Abstract

Provided are a method for manufacturing a photomask, a photomask, and a method for manufacturing a device for a display apparatus. Even if a defect is generated in a photomask utilizing a phase shift effect, precise correction can be performed. A method for manufacturing a photomask having a pattern for transfer including a semi-transmissive portion patterned from a semi-transmissive film formed on a transparent substrate, the method including: in a case where a defect is generated in the semi-transmissive portion, a step of determining the defect to be corrected and deciding a correction region in which a correction film for correcting the defect is to be formed; and a correction film forming step of forming the correction film in the correction region, in which a first film having a higher transmittance than the semi-transmissive film and a second film having a transmittance for adjusting the transmittance of the correction film are sequentially stacked.

Description

[0001] This application is filed in accordance with Article 42 of the Implementing Regulations of the Patent Law and is a divisional application of the invention patent application No. 201910689040.4, filed on July 29, 2019, entitled "Photomask, Method for Modifying It, Manufacturing Method, Method for Manufacturing Device of Display Device". Technical Field

[0002] This invention relates to a method for manufacturing a photomask that corrects defects generated on the photomask, and more particularly to a method for manufacturing a photomask suitable for manufacturing a display device, and a method for manufacturing a photomask and a device for a display device. Background Technology

[0003] As photomasks used in semiconductor integrated circuits, attenuation-type (or halftone) phase-shift masks are known. These phase-shift masks are formed by creating a portion of the light-shielding area, equivalent to a binary mask, using a halftone film with low transmittance and a 180-degree phase shift.

[0004] Patent Document 1 describes a solution in which, when a defect is generated in the phase-shifting section having such a phase-shifting mask, a correction component having almost the same transmittance and almost the same phase shift amount as the phase-shifting section is arranged in the phase-shifting defect section.

[0005] On the other hand, it is known that multitone masks are used in the manufacture of liquid crystal display devices to improve production efficiency. Patent Document 2 describes a method in which, in addition to a light-blocking portion and a light-transmitting portion, a semi-transparent portion on a transparent substrate has a semi-transparent film formed thereon. A correction film is formed on defects generated in this semi-transparent portion to correct them. As a result, the phase difference between the light-transmitting portion exposed on the transparent substrate and the correction portion on which the correction film is formed is less than 80 degrees. Therefore, at the boundary between adjacent light-transmitting portions and correction portions, defects such as short circuits in thin-film transistor channels caused by reduced transmittance due to the phase difference can be suppressed.

[0006] Furthermore, Patent Document 3 proposes a scheme for using a photomask with a phase-shifting film having high transmittance (30% or more) in the manufacture of a display device.

[0007] Existing technical documents

[0008] Patent documents:

[0009] Patent Document 1: Japanese Patent Application Publication No. 7-146544

[0010] Patent Document 2: Japanese Patent Application Publication No. 2010-198006

[0011] Patent Document 3: Japanese Patent Application Publication No. 2016-71059 Summary of the Invention

[0012] The problem the invention aims to solve

[0013] For example, when defects occur in the patterned portion of a halftone phase-shift mask formed by halftone films, correcting these defects may not be easy. It is generally known that when defects occur in a photomask and it is desired to correct these defects using a correction film, a FIB (Focused Ion Beam) device is used as the correction unit.

[0014] The FIB device primarily uses gallium ions to deposit carbon-based films. However, according to the inventors' research, the method of simply depositing a correction film on the defective portion of a photomask using an FIB device sometimes fails to restore the same functionality as a photomask without defects. The correction operation is easier if the photomask to be corrected is a so-called binary mask. On the other hand, the inventors' research shows that when the target of correction is a halftone phase-shift mask, even using the aforementioned FIB device, depositing the correction film on the defective portion of the photomask results in a phase shift of approximately 180 degrees relative to the exposure light, and it is difficult to form a correction film with the desired transmittance set for the normal halftone portion. This is also related to the fact that the FIB device is designed for the correction of the light-shielding film and does not anticipate the possibility of separately adjusting the phase shift and transmittance to desired values. That is, there is a problem: in order to study the possibility of applying FIB devices to the correction of phase shift masks, it is necessary to start by exploring the raw materials and formation conditions of the correction film. Even on this basis, based on the results of these efforts, it may not be possible to achieve different optical properties such as transmittance depending on the phase shift mask.

[0015] Furthermore, while FIB-based defect correction is advantageous for depositing correction films for minor defects, the laser CVD method, described later, is more efficient in rapidly and uniformly covering the area requiring correction with the correction film. Therefore, laser CVD is generally more advantageous than FIB-based methods in the correction of photomasks used in the manufacture of large-sized display devices (hereinafter referred to as "FPD").

[0016] In the aforementioned Patent Document 2, laser CVD is used to correct defects in the semi-transparent film forming the semi-transparent portion. This method allows for the efficient deposition of correction films on defective areas, making it easier to apply in large-scale FPD photomasks. However, the correction film formed in this way is for semi-transparent films that do not have a phase-shifting effect.

[0017] Currently, in display devices, the trend towards higher resolution is significant, accompanied by an increase in pixel density. Furthermore, portable devices particularly demand high brightness and power efficiency. Moreover, to achieve these, the photomasks used in the manufacturing process also include minute components, requiring technologies that can reliably resolve these minute parts. The trend towards improved resolution is not limited to exposure equipment; technologies that improve the resolution of photomasks as well can be considered. Therefore, Patent Document 3 mentioned above proposes a transfer pattern using phase-shifting action in the photomask for FPDs.

[0018] However, obtaining a correction film with the same transmittance and phase shift as the initially formed semi-transparent film (hereinafter also referred to as "normal semi-transparent film") in the photomask manufacturing process, which addresses defects generated in semi-transparent films with phase-shifting effects, presents significant difficulties. In particular, a method for forming a correction film for semi-transparent portions with high transmittance (e.g., 25% or more) and phase-shifting effects has not been established.

[0019] The main objective of this invention is to provide a technique that enables precise correction even when defects are generated in a photomask utilizing phase shifting.

[0020] means for solving problems

[0021] (Part 1)

[0022] The first aspect of the present invention discloses a method for manufacturing a photomask, wherein the photomask has a transfer pattern, the transfer pattern comprising a semi-transparent portion formed by patterning a semi-transparent film formed on a transparent substrate.

[0023] The method for manufacturing the photomask includes the following steps:

[0024] In the event of a defect in the semi-transparent portion,

[0025] The steps of identifying the defect to be corrected, determining the correction area for forming a correction film to correct the defect; and

[0026] The correction film forming process involves forming the correction film in the correction area.

[0027] In the modified film formation process, the first film and the second film are stacked sequentially.

[0028] The first film has a higher transmittance than the semi-transparent film.

[0029] The second membrane has a transmittance for adjusting the transmittance of the modified membrane.

[0030] (Part 2)

[0031] The second aspect of the present invention is characterized in that,

[0032] The transfer pattern also includes a light-blocking portion with an optical density (OD) of 3 or higher for the exposed light.

[0033] (Part 3)

[0034] The method for manufacturing a photomask according to the third aspect of the present invention, wherein,

[0035] In the process of determining the correction area, the correction area is determined as the area where the edge of the correction film is separated from the edge of the light-shielding portion.

[0036] (Aspect 4)

[0037] The fourth aspect of the present invention is characterized in that,

[0038] According to the method for manufacturing a photomask according to the third aspect above, the method further includes the following step: forming a supplementary film in such a way as to cover at least the edge of the correction film and the edge of the light-shielding portion, thereby modifying the shape of the correction semi-transparent portion, wherein the supplementary film is composed of a material different from the light-shielding film.

[0039] (Part 5)

[0040] The fifth aspect of the present invention is characterized in that,

[0041] The method for manufacturing a photomask according to any aspect of the second aspect above, wherein the semi-transparent portion is arranged such that it is sandwiched between the light-shielding portion and the light-blocking portion.

[0042] (Sixth aspect)

[0043] The sixth aspect of the present invention is characterized in that,

[0044] According to the photomask manufacturing method described in aspect 1 or 2 above, wherein,

[0045] When the transmittance of the first film to the representative wavelength of the exposure light is set to T1 and the phase shift is set to Φ1, and the transmittance of the second film to the representative wavelength is set to T2 and the phase shift is set to Φ2, the following relationships (1) to (5) are satisfied, and the exposure light uses light with a wavelength of 300nm to 500nm:

[0046] (1) 100 degrees ≤ Φ1 < 200 degrees

[0047] (2) 20 degrees ≤ Φ2 < 100 degrees

[0048] (3) T1>T2

[0049] (4) 55% ≤ T1 ≤ 95%

[0050] (5) 25% <T2<80%。

[0051] (Part 7)

[0052] The seventh aspect of the present invention is characterized in that,

[0053] According to the photomask manufacturing method described in the first or second aspect above, the composition or physical properties of the first film and the second film are different from each other.

[0054] (Aspect 8)

[0055] The eighth aspect of the present invention is characterized in that,

[0056] According to the photomask manufacturing method described in aspect 1 or 2 above, wherein,

[0057] The transmittance Tm of the semi-transparent portion for light of the representative wavelength is 25% < Tm ≤ 80%.

[0058] (Aspect 9)

[0059] The ninth aspect of the present invention is characterized in that,

[0060] According to the method for manufacturing a photomask described in the first or second aspect above, the phase shift Φm of the semi-transparent portion for light of the representative wavelength is 160 degrees ≤ Φm ≤ 200 degrees.

[0061] (Aspect 10)

[0062] The tenth aspect of the present invention is characterized in that,

[0063] A photomask has a transfer pattern comprising a semi-transparent portion formed by patterning a semi-transparent film formed on a transparent substrate, wherein...

[0064] The photomask includes a modified semi-transparent portion on which a modified film is locally formed, the modified film comprising a material different from the semi-transparent film.

[0065] The correction film is a laminated film formed by sequentially stacking a first film and a second film.

[0066] The first film has a higher transmittance than the semi-transparent film.

[0067] The second membrane has a transmittance for adjusting the transmittance of the modified membrane.

[0068] (Aspect 11)

[0069] The eleventh aspect of the present invention is characterized in that,

[0070] According to the optical mask described in aspect 10 above, wherein,

[0071] The transfer pattern also includes a light-blocking portion with an optical density (OD) of 3 or higher for the exposed light.

[0072] (Aspect 12)

[0073] The 12th aspect of the present invention is characterized in that,

[0074] According to the photomask described in aspect 11 above, the edge of the modified semi-transparent portion is separated from the edge of the light-shielding portion.

[0075] (Aspect 13)

[0076] The 13th aspect of the present invention is characterized in that,

[0077] According to the photomask described in aspect 12 above, wherein,

[0078] A supplementary film is formed such that it at least covers the edges of the modified semi-transparent portion and the edges of the light-shielding portion, and the supplementary film is composed of a material with a different composition than the light-shielding film.

[0079] (Aspect 14)

[0080] The 14th aspect of the present invention is characterized in that,

[0081] According to the optical mask described in aspect 11 above, wherein,

[0082] The semi-transparent portion is arranged such that it is sandwiched between the light-blocking portion.

[0083] (Aspect 15)

[0084] The method for manufacturing a photomask according to aspect 15 of the present invention is characterized in that, according to the photomask described in aspect 10 or 11 above, when the transmittance of the first film to the representative wavelength of the exposure light is set to T1 and the phase shift is set to Φ1, and the transmittance of the second film to the representative wavelength is set to T2 and the phase shift is set to Φ2, the following relationships (1) to (5) are satisfied, and the exposure light uses light with a wavelength of 300 nm to 500 nm:

[0085] (1) 100 degrees ≤ Φ1 < 200 degrees

[0086] (2) 20 degrees ≤ Φ2 < 100 degrees

[0087] (3) T1>T2

[0088] (4) 55% ≤ T1 ≤ 95%

[0089] (5) 25% <T2<80%。

[0090] (Aspect 16)

[0091] The photomask of the 16th aspect of the present invention has a transfer pattern, wherein the composition or physical properties of the first film and the second film are different from each other according to the photomask of the 10th or 11th aspect described above.

[0092] (Aspect 17)

[0093] The 17th aspect of the present invention is characterized in that,

[0094] According to the optical mask described in aspect 16,

[0095] The transmittance Tm of the semi-transparent portion for light of the representative wavelength is 25% < Tm ≤ 80%.

[0096] (Aspect 18)

[0097] The 18th aspect of the present invention is characterized in that,

[0098] According to the optical mask described in aspect 10 or 11, wherein,

[0099] The phase shift Φm of the semi-transparent portion for the light representing the wavelength is 160 degrees ≤ Φm ≤ 200 degrees.

[0100] (Aspect 19)

[0101] The 19th aspect of the present invention is characterized in that,

[0102] A method for manufacturing a component for a display device, wherein,

[0103] The manufacturing method of the device for the display device includes the following steps:

[0104] The process of preparing the photomask described in aspect 10 or aspect 11; and

[0105] The transfer process involves exposing the photomask to an exposure device to transfer the transfer pattern onto the object to be transferred.

[0106] Invention Effects

[0107] According to the present invention, even if defects are generated in a photomask utilizing phase shifting, precise correction can be performed. Attached Figure Description

[0108] Figure 1The following diagrams are illustrations that schematically show the outline of the photomask correction method in the first embodiment of the present invention: (a) is a diagram showing an example of a normal pattern, (b) is a diagram showing an example of a white defect, (c) is a diagram showing an example of the formation of a first film, and (d) is a diagram showing an example of the formation of a second film.

[0109] Figure 2 The following diagrams are illustrations that schematically show the outline of the photomask correction method in the second embodiment of the present invention: (a) shows an example of a normal pattern; (b) shows an example of a white defect; (c) shows an example of film removal around the defect; (d) shows an example of first film formation; (e) shows an example of second formation; and (f) shows an example of light-shielding supplementary film formation.

[0110] Figure 3 The following diagrams are illustrations that schematically show the outline of the photomask correction method in the third embodiment of the present invention: (a) shows an example of a normal pattern; (b) shows an example of a white defect; (c) shows an example of film removal around the defect; (d) shows an example of first film formation; (e) shows an example of second film formation; and (f) shows an example of light-shielding supplementary film formation.

[0111] Figure 4 Explanatory diagrams illustrating the optical properties of the correction film formed by the photomask correction method of the present invention are shown below: (a) is a diagram showing a specific example of the relationship between phase shift and transmittance when the first film, which is a phase shift control film, is a single layer; (b) is a diagram showing a specific example of the relationship between phase difference and transmittance when the second film, which is a transmission control film, is a single layer; and (c) is a diagram showing a specific example of the relationship between phase shift and transmittance of the correction film (stacked film) obtained by stacking the first film and the second film.

[0112] Label Explanation:

[0113] 1…Transparent substrate

[0114] 2… Semi-transparent film

[0115] 3…Light-shielding film

[0116] 4… Correction film

[0117] 4a…First membrane

[0118] 4b…Second membrane

[0119] 5…Replenishing membrane

[0120] 10, 10'... Transfer pattern

[0121] 11…Light-transmitting section

[0122] 12… Semi-transparent section

[0123] 12a… Correction of semi-transparent part

[0124] 13…Light shielding part

[0125] 20…white defects

[0126] 21, 22… Correction areas Detailed Implementation

[0127] Hereinafter, embodiments of the photomask correction method, photomask manufacturing method, photomask, and display device manufacturing method involved in the present invention will be described.

[0128] When defects occur in the transfer pattern formed on a transparent substrate, the photomask correction method involved in this invention can be applied.

[0129] <Photomask as an object of defect correction>

[0130] Here, the photomask to which the photomask correction method of the present invention is applied will be described.

[0131] The photomask used in the photomask correction method of the present invention has a transfer pattern formed on a transparent substrate by patterning one or more optical films. At least one of the optical films is a semi-transparent film having a predetermined transmittance and phase shift effect for exposure light. This semi-transparent film is a film that shifts the phase of the transmitted exposure light by a desired amount.

[0132] That is, the object of the photomask correction method of the present invention can be a photomask blank (or photomask intermediate) on which at least the above-mentioned semi-transparent film is formed on a transparent substrate, and a photomask or photomask intermediate is formed with a transfer pattern by a photolithography process.

[0133] Regarding the transfer pattern, for example, a transfer pattern consisting of a light-transmitting portion and a semi-transmitting portion formed by patterning a semi-transparent film formed on a transparent substrate is provided. Alternatively, a transfer pattern having a light-transmitting portion, a light-shielding portion, and a semi-transmitting portion formed by patterning a semi-transparent film and a light-shielding film formed on a transparent substrate may also be provided. However, a transfer pattern that also has an additional film pattern may also be provided.

[0134] The present invention can be advantageously applied when the photomask is a photomask for an FPD.

[0135] Photomasks used for FPDs differ from those used in semiconductor device manufacturing. They are generally large in size (for example, one side of the main surface is a quadrilateral of about 200 to 2000 mm, and the thickness is about 5 to 20 mm) and have weight. In addition, their sizes vary widely.

[0136] As a transparent substrate, there are no particular restrictions as long as it has sufficient transparency for the exposure wavelength used in the photomask exposure. For example, quartz and various other glass substrates (soda-lime glass, aluminosilicate glass, etc.) can be used, but quartz substrates are particularly preferred.

[0137] The optical properties of the semi-transparent film constituting the semi-transparent part are exemplified below.

[0138] The photomask correction method of the present invention targets a semi-transparent portion having a transmittance Tm (%) for a representative wavelength of the exposure light. The effect of the present invention is particularly significant when 25 < Tm is satisfied. For example, 25 < Tm ≤ 80.

[0139] In addition, in the specification of this application, the transmittance is the transmittance when the transmittance of the transparent substrate is set to 100%.

[0140] Here, the exposure light can be light with a wavelength mainly of 300 to 500 nm as the light source of the exposure apparatus for the photomask of the FPD. For example, it is preferable to use a light source having a wavelength range including any one or more of the i-line, h-line, and g-line, and in particular, high-pressure mercury lamps including these wavelengths are more commonly used.

[0141] In this case, the representative wavelength of the exposure light can be any wavelength contained within the wavelength range of lines i to g. For example, line h (405 nm), which is close to the midpoint of these wavelength ranges, can be used as the representative wavelength. In the following description, unless otherwise specified, line h will be used as the representative wavelength. Of course, wavelengths shorter than the aforementioned wavelengths (e.g., 300–365 nm) can also be used as the exposure light.

[0142] Furthermore, the phase shift Φm of the semi-transparent film can be set to approximately 180 degrees for the light of the representative wavelength. Here, approximately 180 degrees refers to a range of 160 to 200 degrees. More preferably, it is set to have a phase shift of 160 to 200 degrees for all the main wavelengths (e.g., i-line, h-line, g-line) included in the exposure light.

[0143] The preferred phase shift deviation in the wavelength domain of the i-line to g-line is less than 40 degrees.

[0144] Furthermore, photomasks with semi-transparent portions having the aforementioned transmittance Tm and phase shift Φm can improve the resolution of the transfer pattern compared to so-called binary masks. For example, photomasks are known where the transparent and semi-transparent portions are arranged adjacently, improving resolution through diffraction and interference caused by the transmitted light generated at the boundary. In such so-called phase-shifting masks, the mainstream practice is to set the transmittance of the semi-transparent portion to 10% or less.

[0145] On the other hand, in addition to the light-transmitting portion and the semi-light-transmitting portion, the transfer pattern may also have a light-shielding portion. That is, a photomask having a transfer pattern formed by patterning a semi-light-transmitting film and a light-shielding film formed on a transparent substrate can also be the object of the photomask correction method of the present invention.

[0146] For example, as in the photomask described in Patent Document 3, when the light-transmitting part and the semi-transparent part are not adjacent and the light-shielding part is arranged between the light-transmitting part and the semi-transparent part, and when the semi-transparent part is further sandwiched by the intervening light-shielding part, by utilizing the light that passes through the semi-transparent part and is in the opposite phase to the light-transmitting part, the following advantages can be obtained: that is, the depth of focus is increased, and on this basis, the MEEF (mask error amplification factor) and the amount of light energy required for exposure are reduced.

[0147] Therefore, sometimes a transfer pattern is designed as follows: the semi-transparent portion with phase-shifting function is not directly adjacent to the transparent portion, but is positioned at a predetermined location nearby via a light-blocking portion or a semi-transparent portion that does not substantially have phase-shifting function. In this case, it is useful to design the transmittance Tm of the semi-transparent portion with phase-shifting function to be relatively high (e.g., Tm > 25) compared to the transmittance of a typical halftone phase-shifting mask (e.g., 10% or less), which significantly improves resolution performance. For such a high-transmittance phase-shifting semi-transparent portion, a more preferred range for the transmittance Tm is 30 < Tm ≤ 75, and more preferably 40 < Tm ≤ 70. In this case, the transmitted light from the semi-transparent portion can appropriately interfere with the transmitted light from the transparent portion separated from the semi-transparent portion by a predetermined distance, thereby improving the light intensity profile of the transmitted light formed in the transparent portion.

[0148] Therefore, when defects occur in the semi-transparent portion with high transmittance and phase-shifting effect, these defects must be corrected.

[0149] To correct the related defects, the photomask correction method of the present invention is applied.

[0150] <First Embodiment of the Photomask Correction Method>

[0151] The following is for reference Figure 1The first embodiment of the photomask correction method of the present invention will be described.

[0152] Figure 1 (a) shows the normal pattern portion of the photomask to be corrected in the first embodiment. The transfer pattern 10 to be corrected in the first embodiment has a light-transmitting portion 11 exposed on the transparent substrate 1 and a semi-transmitting portion 12 on the transparent substrate 1 where a semi-transmitting film 2 with a phase-shifting effect is formed.

[0153] First, in the defect identification process, the defect generated in the semi-transparent film 2 is identified and designated as the target for correction. For the white defect caused by the absence of the semi-transparent film 2, the correction area for forming the correction film 4 (described later) is first determined. As needed, a process (pre-treatment process) can be performed to remove the defective portion, or unwanted film (residual semi-transparent film 2) or foreign matter around the defect location. After reshaping the shape of the correction area for forming the correction film 4, the correction film 4 is formed. Unwanted residual film 2 can be removed using laser-based evaporation (laser zap) or similar methods.

[0154] On the other hand, when the present invention is implemented to correct the semi-transparent portion 12 with residual defects such as black defects, foreign matter attachment, or the presence of a light-shielding film that should have been removed by the patterning process, the residual matter is removed in the same manner as described above, and the correction film 4 of the present invention is formed in a state where the transparent substrate 1 is exposed.

[0155] Figure 1 (a) shows a transfer pattern 10 formed by patterning a semi-transparent film 2 with phase-shifting effect formed on a transparent substrate 1. The semi-transparent portion 12 has a transmittance Tm (%) for light of a representative wavelength (here, h-line) of the exposure light, where Tm > 25. Specifically, as described above, for example, it can be set to 25 < Tm ≤ 80. Furthermore, the semi-transparent portion 12 has a phase shift amount Φm for light of the aforementioned representative wavelength. Here, Φm is set to 160 ≤ Φm ≤ 200 (degrees).

[0156] Figure 1 (b) shows a case where a white defect is generated in the semi-transparent portion 12. This white defect can be caused by the absence of the semi-transparent film 2, or it can be an artificial white defect formed by removing the residue from the semi-transparent portion 12 with remaining defects. As will be described in detail later as a correction film formation process, a correction film 4 is formed in the white defect portion 20 to correct it. The correction film 4 can preferably be formed using a laser CVD method.

[0157] Laser CVD is a method of forming a membrane (also known as a laser CVD membrane) by introducing a membrane material and imparting energy through heat and / or light generated by laser irradiation. As membrane materials, metal carbonyl group 6 elements such as Cr(CO)6 (chromium hexacarbonyl), Mo(CO)6 (molybdenum hexacarbonyl), and W(CO)6 (tungsten hexacarbonyl) can be used. Among these, Cr(CO)6 is preferred as a modified membrane material for photomasks due to its excellent chemical resistance to cleaning and other processes. In this first embodiment, the case of using Cr(CO)6 as the membrane material will be described.

[0158] The laser used for irradiation is preferably a laser in the ultraviolet region. A feed gas is introduced into the laser irradiation area, and a film is deposited through photo-CVD and / or thermal CVD. For example, a NdYAG laser with a wavelength of 355 nm can be used. Ar (argon) can be used as the carrier gas, but nitrogen (nitrogen) can also be included.

[0159] In a typical laser CVD apparatus, laser CVD is used to form a light-shielding correction film. However, in this invention, a semi-transparent correction film 4 with phase-shifting properties is formed. For this purpose, conditions such as the flow rate and energy power of the introduced gas are carefully selected.

[0160] like Figure 1 As shown in (d), the correction film 4 of the present invention has a stacked structure of a first film 4a and a second film 4b. For this stacking order, either film can be on top, and furthermore, it is not excluded that additional films may be added without hindering the effect of the present invention. In the following description, the correction film 4 having the desired optical properties is formed by stacking the second film 4b on the first film 4a.

[0161] (Membrane 1)

[0162] Figure 1 (c) shows the process of forming the first membrane 4a.

[0163] In order to make the correction film 4, formed by the lamination of the first film 4a and the second film 4b stacked thereon, have a phase shift of about 180 degrees Φr (degrees) for the representative wavelength of the exposed light, the first film 4a shall have an appropriate phase shift Φ1 (degrees). Preferably, the first film 4a is responsible for more than 50% of the aforementioned phase shift Φr, that is, it functions as a so-called "phase shift control film".

[0164] That is, the phase shift Φ1 of the first membrane 4a and the phase shift Φr of the modified membrane 4 can be set as 160≤Φr≤200 and 100≤Φ1<200.

[0165] The phase shift Φ1 is further preferably 120≤Φ1<180, and more preferably 130≤Φ1<160.

[0166] The transmittance T1 of the first film 4a for light of the aforementioned representative wavelength is preferably set to 55≤T1, more specifically, 55≤T1≤95, more preferably 60≤T1≤80, and even more preferably 60≤T1≤70.

[0167] Furthermore, regarding the aforementioned phase shift, for example, 160≤Φr≤200 refers to the range including 160+360M≤Φr≤200+360M (where M is a non-negative integer). Hereafter, the same meaning will be applied to the phase shift.

[0168] Preferably, the main components of the first membrane 4a are Cr (chromium) and O (oxygen). That is, the total content of Cr and O is 80% or more of the total content of the first membrane 4a. More preferably, the total content of Cr and O is 90% or more, and even more preferably 95% or more.

[0169] In addition, the percentage of membrane component content indicates atomic percentage. The same applies below.

[0170] The first membrane 4a may not contain C (carbon) contained in the feed gas, but if it does, it is preferably 20% or less, more preferably 10% or less. Furthermore, the C content of the first membrane 4a is less than the C content of the second membrane 4b described later, preferably 2 / 3 or less, more preferably 1 / 3 or less.

[0171] Preferably, the largest component (with the largest content) of the first membrane 4a is O, and the content of O is 50% or more.

[0172] The preferred composition of the first membrane 4a is 5-45% Cr and 55-95% O.

[0173] Furthermore, the Cr content of the first membrane 4a is preferably 5-30%.

[0174] The first membrane 4a preferably contains 20-30% Cr and 70-80% O.

[0175] Preferably, the Cr content of the first membrane 4a is less than that of the second membrane 4b, which will be described later.

[0176] By employing the above-described composition, the first film 4a can be a film with high transmittance and sufficient phase shift. Furthermore, the first film 4a can be formed by laser CVD.

[0177] In order to form the first film 4a according to the above composition and achieve the above optical properties, the thickness of the first film 4a is 1000 to 4000 Å, more preferably 1300 to 2500 Å.

[0178] Figure 4(a) illustrates the optical properties of the first film 4a.

[0179] Figure 4 (a) shows a specific example of the relationship between phase shift Φ1 and transmittance when the vertical axis is set to phase shift (degrees) and the horizontal axis is set to transmittance (%), and the first film 4a of the phase shift control film is a single layer.

[0180] (Second membrane)

[0181] Figure 1 (d) shows the process of forming the second membrane 4b on the first membrane 4a.

[0182] The second membrane 4b has a transmittance T2 (%) required to adjust the transmittance Tr (%) of the modified membrane 4 formed by its lamination with the first membrane 4a to a desired value. That is, the second membrane 4b can be set as a so-called "transmission control membrane".

[0183] Preferably, the transmittance T1 of the first membrane 4a and the transmittance T2 of the second membrane 4b are T1 > T2.

[0184] The preferred transmittance T2 of the second membrane 4b is 25 < T2 < 80, more preferably 30 ≤ T2 < 70, and even more preferably 45 ≤ T2 < 65.

[0185] Furthermore, the phase shift Φ2 of the second membrane 4b is less than the phase shift Φ1 of the first membrane 4a, and Φ2 < 100. Specifically, 20 ≤ Φ2 < 100, more preferably 20 ≤ Φ2 < 60, and even more preferably 30 ≤ Φ2 < 50.

[0186] Preferably, the main components of the second membrane 4b are Cr, O, and C. That is, preferably Cr, O, and C constitute more than 90% of the total components of the second membrane 4b, more preferably more than 95%.

[0187] Preferably, the second membrane 4b contains more C than the first membrane 4a.

[0188] Furthermore, it is preferable to set the Cr content of the second membrane 4b to be greater than the Cr content of the first membrane 4a.

[0189] Specifically, the composition of the second membrane 4b can be set to contain 20-70% Cr, 5-45% O, and 10-60% C.

[0190] More preferably, the composition of the second membrane 4b can be set to contain 40-50% Cr, 15-25% O, and 25-35% C.

[0191] When forming the first film 4a and the second film 4b by laser CVD, raw material gases with different compositions or composition ratios can be used, or the same raw material gas can be used with different formation conditions to obtain different compositions and physical properties.

[0192] In this first embodiment, the feed gas for the first membrane 4a and the second membrane 4b is the same (Cr(CO)6), but different formation conditions are applied to each other.

[0193] That is, during the formation of the first membrane 4a, the flow rate of the feed gas is set to be smaller than that of the second membrane 4b (for example, less than 1 / 2, and further to 1 / 8 to 1 / 6, etc.). In addition, the laser irradiation power density can also be set to be smaller than that of the second membrane 4b (for example, less than 1 / 2). These are effective methods for limiting the decomposition reaction of the feed gas and forming a first membrane 4a with sufficient phase shift while ensuring that the transmittance is not too low.

[0194] As an example, the raw material gas flow rate can be less than 30 cc / min, preferably 10 to 20 cc / min. Furthermore, the laser irradiation power density is set to 3 mW / cm². 2 The preferred values ​​are 1–2 mW / cm. 2 Furthermore, the laser irradiation time can be set to 10 seconds or more, preferably 20 to 30 seconds. That is, setting the flow rate of the raw gas used to form the first membrane 4a and the laser irradiation power density to a relatively low flow rate and a relatively low energy is useful for membrane formation over a longer period compared to the second membrane 4b described later.

[0195] On the other hand, when forming the second film 4b, the feed gas flow rate is increased compared to the first film 4a, resulting in a higher C content. Furthermore, the laser irradiation power density used to form the second film 4b is preferably higher than that used for the first film 4a. Therefore, even though the decomposition reaction of the feed gas is promoted and the film thickness is reduced, a second film 4b with a lower transmittance than the first film 4a is formed.

[0196] As an example, the flow rate of the feed gas used to form the second membrane 4b is 60 cc / min or more, preferably around 80 to 110 cc / min. Furthermore, the laser irradiation power density is set to 6 mW / cm². 2 The above values ​​are preferably 8–12 mW / cm. 2 Furthermore, the laser irradiation time can be shorter than that of the first membrane 4a, for example, less than 1.0 second, preferably 0.5 to 0.8 seconds. That is, conditions of relatively high flow rate and relatively high energy, and short time, can be used as the feed gas flow rate and laser irradiation power density for forming the second membrane 4b.

[0197] The formation conditions of this second film 4b can also be referred to as so-called high-energy conditions, which are greater than those applied when using laser CVD to form light-shielding correction films (e.g., when correcting binary masks).

[0198] By applying these conditions, the second membrane 4b becomes a thin film with a very small phase shift Φ2. Furthermore, due to its high density, it also becomes a membrane with excellent chemical resistance.

[0199] With the above composition, as a film that complements the desired optical properties, the thickness of the second film 4b can be set to 450–1450 Å, more preferably 550–950 Å. Preferably, the thickness of the second film 4b is less than the thickness of the first film, thereby reducing the phase shift and making it easier to adjust the phase shift as a correction film.

[0200] Figure 4 (b) illustrates the optical properties of the second film 4b.

[0201] Figure 4 (b) shows a specific example of the relationship between phase shift Φ2 and transmittance T2 when the vertical axis is set to phase shift (degrees) and the horizontal axis is set to transmittance (%), and the second film 4b of the transmission control film is a monolayer.

[0202] (Laminated film)

[0203] By stacking the first film 4a and the second film 4b described above, a correction film 4 can be formed that has the following phase shift Φr (degrees) and transmittance Tr (%) for light of the aforementioned representative wavelength. That is, the correction film 4 obtained by stacking the first film 4a and the second film 4b can be configured as follows:

[0204] 160≤Φr≤200

[0205] Tr > 25.

[0206] The transmittance Tr of the preferred correction film 4 can be in the same range as the transmittance Tm of the semi-transparent part, that is, 30 < Tr ≤ 75, more preferably 40 < Tr ≤ 70.

[0207] The stacking order of the first membrane 4a and the second membrane 4b can be arbitrary. However, due to the difference in composition described above, the second membrane 4b has higher chemical resistance than the first membrane 4a. Therefore, by placing the second membrane 4b on the upper side, it is possible to improve the washability, etc., which is preferred.

[0208] As a modified membrane 4 including the first membrane 4a and the second membrane 4b, the Cr-C-O composition ratio can be set to Cr: 30-70%, O: 5-35%, C: 20-60, more preferably Cr: 40-50%, O: 5-25%, C: 35-45%.

[0209] Figure 4 (c) illustrates the optical properties of the modified film 4 obtained by stacking the first film 4a and the second film 4b.

[0210] Figure 4 (c) shows a specific example of the relationship between the phase shift and transmittance of the modified film 4 obtained by stacking the first film 4a and the second film 4b, with the vertical axis set as the phase shift (degrees) and the horizontal axis set as the transmittance (%). Figure 4 It can be seen that the modified membrane 4 obtained by stacking the first membrane 4a and the second membrane 4b achieves the condition where the first membrane 4a is a single layer (refer to...). Figure 4 (a) or the second membrane 4b is a single layer (see Figure 4 The relationship between phase shift and transmittance cannot be obtained under any of the conditions in (b)), that is, the optical properties of high transmittance and phase shift for exposure light.

[0211] That is, by applying the photomask correction method described above, even if defects occur in a semi-transparent film 2 with a specified transmittance and phase-shifting effect, precise correction can be performed to restore the optical properties. More specifically, according to the photomask correction method of this first embodiment, by setting the correction film 4 as a two-layer structure, correction can be performed to achieve optical properties that are almost identical to those of a high-transmittance phase-shifting film, which are difficult to achieve. Here, since both the first film 4a and the second film 4b can be formed by the same film formation method (here, laser CVD), it is not necessary to use multiple correction devices. This is very advantageous, for example, in the correction of photomasks for manufacturing display devices, as described later.

[0212] In addition, Figure 1 In the first embodiment shown, the semi-transparent portion 12 is adjacent to the transparent portion 11. In this transfer pattern, after the correction film 4 of the required area or more is formed through the above-described process, the edge shape of the correction film 4 at the boundary with the transparent portion 11 can be adjusted by removing the area near the outer edge of the correction film 4. For example, laser zap can be used for this purpose. Therefore, even if the correction film 4 is tilted during its formation, the edge shape of the film closer to the side perpendicular to the transparent substrate 1 can be adjusted, allowing the phase shift effect generated at the boundary to function more effectively.

[0213] <Second Embodiment of the Photomask Correction Method>

[0214] Next, refer to Figure 2 The second embodiment of the photomask correction method of the present invention will be described.

[0215] Figure 2A method for correcting defects is shown for a photomask having a transfer pattern 10´ formed by patterning a semi-transparent film 2 and a light-shielding film 3 on a transparent substrate 1.

[0216] That is, the transfer pattern 10' that is the object of modification in this second embodiment has a light-transmitting portion exposed on the transparent substrate 1, a light-shielding portion 13 on the transparent substrate 1 having at least a light-shielding film 3 formed thereon, and a semi-transparent portion 12 on the transparent substrate 1 having a semi-transparent film 2 having a phase-shifting effect formed thereon. Figure 2 In (a), only the light-shielding portion 13 and the semi-transparent portion 12 are shown; the light-transmitting portion is omitted. An anti-reflective layer may also be formed on the surface of the light-shielding film 3.

[0217] In this second embodiment, the semi-transparent portion 12 and the light-shielding portion 13 are adjacent to each other and are sandwiched together in the direction in which the semi-transparent portion 12 and the light-shielding portion 13 are arranged. Figure 2 In (a), the semi-transparent part 12 is not adjacent to the transparent part.

[0218] Here, the semi-transparent portion 12 is composed of a phase-shifting film having the same transmittance Tm (%) and phase shift Φm (degrees) as in the first embodiment described above. The light-shielding portion 13 is a film that substantially does not transmit exposure light, and is preferably OD (Optical Density) ≥ 3.

[0219] Figure 2 (b) shows in Figure 2 The case shown in (a) is that a white defect 20 is generated in the semi-transparent part 12 of the photomask.

[0220] Figure 2 (c) shows a process (pretreatment process) in which the shape of the area (hereinafter also referred to as the correction area) 21 for forming the correction film 4 is adjusted by removing the semi-transparent film 2 and the light-shielding film 3 located around the white defect 20 to expose the transparent substrate 1. The film removal method can be laser-based evaporation, etc.

[0221] Figure 2 (d) illustrates the process of forming a first film 4a on the surface of the exposed transparent substrate 1 in the correction region 21, similar to the case in the first embodiment. Furthermore, Figure 2 (e) shows that a second membrane 4b is stacked on the first membrane 4a that has been formed.

[0222] The optical properties, composition, and film-forming conditions of the first film 4a and the second film 4b can be the same as those in the first embodiment. Therefore, the resulting two-layer modified film 4 is also the same as that in the first embodiment.

[0223] In this second embodiment, the correction area 21 is adjacent to the light-shielding portion 13 or the semi-transparent portion 12. Furthermore, an example is shown where the correction area 21 is surrounded by the light-shielding portion 13 and / or the semi-transparent portion 12. Here, the correction film is formed such that the edges of the semi-transparent film 2 and / or the light-shielding film 3 forming the outer edge of the correction area 21 do not overlap with the edges of the first film 4a or the second film 4b. This is because if the first film 4a and / or the second film 4b overlaps with the edge of the remaining semi-transparent film 2, the transmittance of the overlapping portion is lower than that of the normal semi-transparent film 2, resulting in a defect where the designed pattern is not transferred.

[0224] Furthermore, this is because when the first film 4a and / or the second film 4b overlap with the edge of the residual light-shielding portion 13, energy is irradiated onto the components of the light-shielding film 3 (e.g., Cr) at the edge portion of the light-shielding film 3, thereby causing unwanted film growth to begin, resulting in a change in the transmittance of the nearby semi-transparent portion (including the modified portion) 12.

[0225] Therefore, it is preferable to perform a correction process that adjusts the edge position so that the edges of the first film 4a and / or the second film 4b do not overlap with the edges of the semi-transparent film 2 and the light-shielding film 3 remaining on the transparent substrate 1. Alternatively, as... Figure 2 As shown in (c) and (d), it is preferable to apply a correction process in which the edges of the first film 4a and / or the second film 4b are slightly separated from the edges of the semi-transparent film 2 and the light-shielding film 3 remaining on the transparent substrate 1.

[0226] Preferably, the separation distance between the edge of the first film 4a and / or the second film 4b and the edge of the semi-transparent film 2 and the light-shielding film 3 is less than 1 μm. For example, the separation distance can be set to 0.1 μm to 1 μm. Since this separation distance is less than the resolution limitation of the exposure device that exposes the photomask, the separation portion will essentially not be transferred onto the substrate.

[0227] Furthermore, in this second embodiment, in Figure 2 In the pretreatment step (c), since the light-shielding part 13 is subjected to related film removal, the formation of the correction film 4 is completed. Figure 2 At time (e), the shape of the modified semi-transparent portion (also referred to as the modified semi-transparent portion where a modification film is formed on part or all of the semi-transparent portion) 12a is different from the shape of the normal pattern. Specifically, the width (CD) of the modified semi-transparent portion 12a is greater than the width (CD) of the semi-transparent portion 12 in the normal pattern.

[0228] Therefore, in Figure 2 The (f) process is used to perform the post-processing steps to make it into the designed CD.

[0229] That is, in Figure 2 In (f), a light-shielding supplementary film 5 is formed around its edges to make the corrected semi-transparent portion 12a a correct CD. The supplementary film 5 can be formed, for example, by focused ion beam deposition (FID) or by laser CVD.

[0230] The film-forming method of supplementary film 5 may differ from that of light-shielding film 3 in the normal pattern, thus resulting in different compositions or component ratios, i.e., different compositions from light-shielding film 3. Supplementary film 5 may, for example, be a film with carbon as the main component.

[0231] Preferably, the supplementary film 5 is optically nontransmissive to exposure light, with an OD (Optical Density) of 3 or higher.

[0232] exist Figure 2 In (f), a supplementary film 5 is formed so that the CD of the corrected semi-transparent portion 12a is the same as that of the normal semi-transparent portion 12 before correction. However, if the transmittance of the corrected semi-transparent portion 12a is excessive or insufficient relative to the target value, it is possible to make the CD of the corrected semi-transparent portion 12a larger or smaller than that of the normal semi-transparent portion 12 for the purpose of fine adjustment to approach the target value.

[0233] That is, after the formation process of the correction film 4 is completed and before the later process, the optical performance of the correction film 4 is checked. Based on the results, the size of the supplementary film 5 formed in the later process can be adjusted. In this case, the CD of the formed correction semi-transparent portion 12a is locally smaller or locally larger than that of the normal semi-transparent portion 12.

[0234] By applying the photomask correction method described above, similar to the case of the first embodiment described above, it is possible to precisely correct defects generated in the semi-transparent film 2 that has a specified transmittance and a phase-shifting effect.

[0235] <Third Embodiment of the Photomask Correction Method>

[0236] Next, refer to Figure 3 The third embodiment of the photomask correction method of the present invention will be described.

[0237] Figure 3 Further methods for correcting defects are shown in a photomask having a transfer pattern 10´ formed by patterning a semi-transparent film 2 and a light-shielding film 3 on a transparent substrate 1.

[0238] In this third embodiment, the transfer pattern 10', which is the target of the modification, has a light-transmitting portion exposed on a transparent substrate 1, a light-shielding portion 13 on which at least a light-shielding film 3 is formed, and a semi-transmitting portion 12 on which a semi-transmitting film 2 with a phase-shifting effect is formed. Figure 3 Only the light-shielding portion 13 and the semi-transparent portion 12 are shown in (a), and the light-transmitting portion is omitted. An anti-reflective layer may be formed on the surface of the light-shielding film 3.

[0239] In this third embodiment, the semi-transparent portion 12 is adjacent to the light-shielding portion 13, but not adjacent to the transparent portion.

[0240] Here, the semi-transparent portion 12 is composed of a phase-shifting film having the same transmittance Tm (%) and phase shift Φm (degrees) as in the first embodiment described above. The light-shielding portion 13 is a film that substantially does not transmit exposure light, preferably with an OD ≥ 3.

[0241] Figure 3 (b) shows in Figure 3 The case where a white defect 20 is generated in the semi-transparent part 12 of the photomask shown in (a).

[0242] Figure 3 (c) shows a pretreatment process in which all the translucent films 2 connected to the translucent portion 12 where the white defect 20 was generated are removed, exposing the transparent substrate 1, and the shape of the correction area 22 is adjusted. Additionally, a portion of the adjacent light-shielding film 3 is also removed during the removal of the translucent films 2. The film removal method can employ laser-based evaporation, etc.

[0243] Figure 3 (d) illustrates the process of forming a first film 4a as a phase adjustment film on the exposed surface of the transparent substrate 1 in the correction region 22, similar to the case in the first embodiment. Furthermore, Figure 3 (e) shows a second membrane 4b stacked on the formed first membrane 4a as a transmission adjustment membrane.

[0244] The optical properties, composition, and film-forming conditions of the first film 4a and the second film 4b can be applied in the same way as in the first embodiment. Therefore, the resulting two-layer modified film 4 is also the same as in the first embodiment.

[0245] In this third embodiment, since all semi-transparent films 2 continuous with the defective semi-transparent film are removed, the corrected film and the normal semi-transparent film are not adjacent in the corrected photomask. Therefore, there is no separation or overlap between the two films at the boundary between the corrected film and the normal semi-transparent film. When the size increases, there is a risk that separation or overlap will be transferred onto the substrate, but this risk does not exist in this third embodiment, which is advantageous.

[0246] Furthermore, in this third embodiment, in Figure 3 In the pretreatment step (c), the film removal related to the light-shielding part 13 is performed, so that the formation of the correction film 4 is completed. Figure 3 At time (e), the size of the corrected translucent portion 12a differs from the size of the normal pattern. Specifically, the width (CD) of the corrected translucent portion 12a is greater than the width (CD) of the translucent portion 12 in the normal pattern.

[0247] Therefore, in Figure 3 In (f), a later process is carried out to make it into the CD as designed. This point is the same as in the second embodiment.

[0248] The composition and optical properties of the light-shielding supplementary film 5 formed in the later process can also be the same as in the second embodiment. Furthermore, the transmittance of the modified semi-transparent portion 12a can be adjusted as needed by adjusting the formation size of the supplementary film 5, just as in the second embodiment.

[0249] By applying the photomask correction method described above, similar to the case of the first embodiment described above, it is possible to precisely correct defects generated in a semi-transparent film 2 that has a specified transmittance and a phase-shifting effect.

[0250] <Methods for Manufacturing Photomasks>

[0251] In addition, the present invention includes a method for manufacturing a photomask that includes the photomask correction method described above.

[0252] The method for manufacturing the photomask of the present invention can be carried out through the following steps.

[0253] First, a photomask blank is prepared, comprising a semi-transparent film with phase-shifting properties and the necessary optical film formed on a transparent substrate. This photomask blank includes a photomask intermediate that already has a portion of the film pattern. Then, a desired pattern is drawn on the resist film (positive or negative) formed on the photomask blank using a laser drawing device or the like, and the image is developed to form a resist pattern. Next, using this resist pattern as a mask, the aforementioned optical film is etched to form a transfer pattern. Etching can be performed using either dry etching or wet etching, but wet etching is advantageous for display devices and is therefore commonly used.

[0254] Defect inspection is performed on the photomask (or, further, the photomask intermediate formed by film or pattern formation) with the transfer pattern formed. If white defects or black defects are found, the photomask correction method of the present invention described above is applied to correct the photomask.

[0255] Through the above process, even if defects occur in the transfer pattern that utilizes phase shifting, precise corrections can be made, and a photomask can be manufactured simultaneously.

[0256] <Photomask>

[0257] Furthermore, the present invention includes a photomask that has undergone the above-described photomask correction method.

[0258] The photomask includes a transfer pattern for a semi-transparent portion formed by patterning a semi-transparent film formed on a transparent substrate. Furthermore, the photomask also includes a corrected semi-transparent portion having a corrective film formed locally, comprising a corrective film of a different material from the semi-transparent film. The photomask is obtained by forming a corrective film to address defects in the semi-transparent portion.

[0259] The semi-transparent portion of the photomask has a transmittance Tm (%) for light of a representative wavelength of the exposure light (where Tm > 25) and a phase shift Φm (degrees) (where 160 ≤ Φm ≤ 200).

[0260] The modified film has a laminated film obtained by stacking a first film including Cr and O and a second film including Cr, C and O in any order.

[0261] The first membrane does not contain C, or contains C in a lesser amount than that in the second membrane.

[0262] The second membrane contains O in a lesser amount than that in the first membrane.

[0263] That is, the photomask has a normal semi-transparent part and a modified semi-transparent part.

[0264] In addition, the transfer pattern may also include a light-shielding portion that is substantially nontransmissive to the exposure light.

[0265] In this case, the light-shielding part is formed by forming at least a light-shielding film on a transparent substrate, or it may be a stacked structure in which a semi-transparent film is formed on the upper or lower side of the light-shielding film.

[0266] The stacking order of the first and second films, the optical properties or composition of the first and second films, and the optical properties or composition of the modified film formed by stacking are described in connection with the photomask correction method described above.

[0267] If the photomask has the structure described above, since a modified semi-transparent part is formed that precisely corrects the defects produced by the semi-transparent film 2 with a specified transmittance and a specified phase shift effect, it is very useful for achieving high resolution by utilizing the phase shift effect.

[0268] In addition, examples of materials for normal semi-transparent films include those containing chromium (Cr), or those containing transition metals and Si (silicon). Examples include materials containing Cr or Cr compounds (preferably CrO, CrC, CrN, CrON, etc.), or materials containing at least one of Z (zirconium), Nb (niobium), Hf (hafnium), Ta (tantalum), Mo (molybdenum), Ti (titanium), and Si. Alternatively, materials composed of oxides, nitrides, oxynitrides, carbides, or oxynitrides of these materials may also be used. More specifically, examples include molybdenum silicon nitride (MoSiN), molybdenum oxynitride (MoSiON), molybdenum oxynitride (MoSiN), silicon oxynitride (SiON), and titanium oxide nitride (TiON).

[0269] Furthermore, the material of the light-shielding film can be, for example, Cr or its compounds (oxides, nitrides, carbides, oxynitrides, or oxycarbides), or it can be a silicide containing metals such as Mo, W (tungsten), Ta, or Ti, or the aforementioned compounds of such silicides. Preferably, the material of the light-shielding film is one capable of wet etching. Preferably, the material of the light-shielding film is one that exhibits etching selectivity relative to the material of the semi-transparent film. That is, preferably, the light-shielding film is resistant to the etchant of the semi-transparent film, and further preferably, the semi-transparent film is resistant to the etchant of the light-shielding film.

[0270] There are no particular limitations on the use of the photomask of the present invention.

[0271] For the present invention, as a photomask utilizing phase-shifting action, it is preferable to use a photomask for manufacturing display devices including a small pattern width (CD). The present invention advantageously utilizes, for example, a phase-shifting mask having a hole pattern with a CD (diameter) of 3 μm or less (1.0–2.5 μm, and further 1.0–2.0 μm, for more sophisticated display devices) on a transfer substrate, and uses a semi-transparent film with phase-shifting action. Alternatively, the present invention can be applied to line and space patterns having the aforementioned CD (line width, or space width). In particular, as a photomask using a high-transmittance phase-shifting film, which is the object of the present invention, a photomask using a semi-transparent film is cited to improve the resolution of isolated patterns. Here, when multiple patterns are arranged in a prescribed regularity, and patterns that mutually influence each other are designated as dense patterns, the other patterns are designated as isolated patterns.

[0272] <Manufacturing Method of Devices for Display Devices>

[0273] This invention includes a method for manufacturing a display device using a photomask with the above-described structure. The manufacturing method includes a step of exposing a transfer pattern of the photomask to an exposure apparatus using an exposure apparatus, thereby transferring the pattern onto a substrate. The exposure apparatus can be either a projection apparatus or a proximity apparatus. For manufacturing high-precision devices based on phase shifting and capable of precisely resolving minute patterns, the former is more advantageous.

[0274] For optical conditions when using projection for exposure, it is preferable that the numerical aperture (NA) of the optical system is 0.08 to 0.15, and it is preferable that the exposure light source includes the i-line. Of course, exposure using a wavelength range including the i-line to the g-line is also possible.

[0275] According to the manufacturing method of the display device of the present invention, since the correction film is configured as a two-layer structure to correct defects in the semi-transparent portion, it is possible to perform corrections to achieve optical properties that are almost identical to those of a high-transmittance phase-shifting film, which are difficult to achieve otherwise. That is, defects arising from a semi-transparent film with high transmittance and phase-shifting effect can be precisely corrected. Here, both the first and second films constituting the correction film can be formed by laser CVD, thus eliminating the need for multiple correction devices, which is particularly advantageous in the correction of photomasks used in the manufacture of large-sized display devices.

[0276] <Variation Example>

[0277] The photomask correction method, photomask manufacturing method, photomask, and display device manufacturing method involved in this invention are not limited to the aspects disclosed in the above embodiments, as long as the above-mentioned effects are not lost.

[0278] For example, as described above, the present invention is very useful for photomasks used in the manufacture of display devices, but the application of photomasks is not particularly limited and can also be applied to photomasks used in the manufacture of semiconductor devices.

[0279] Furthermore, the photomask used in this invention may be part of a phase-shifting film or a light-shielding film, or may have other optical films or functional films in addition to a phase-shifting film or a light-shielding film.

Claims

1. A method for manufacturing a photomask, the photomask having a transfer pattern, the transfer pattern comprising a semi-transparent portion formed by patterning a semi-transparent film formed on a transparent substrate. The method for manufacturing the photomask includes the following steps: In the event of a defect in the semi-transparent portion, The steps of identifying the defect to be corrected, determining the correction area for forming a correction film to correct the defect; and The correction film forming process involves forming the correction film in the correction area. In the modified film formation process, the first film and the second film are stacked sequentially. The first film has a higher transmittance than the semi-transparent film. The second membrane has a transmittance for adjusting the transmittance of the modified membrane. When the transmittance of the first film to the representative wavelength of the exposure light is set to T1 and the phase shift is set to Φ1, and the transmittance of the second film to the representative wavelength is set to T2 and the phase shift is set to Φ2, the following relationships (1) to (5) are satisfied, and the exposure light uses light with a wavelength of 300nm to 500nm: (1) 100 degrees ≤ Φ1 < 200 degrees (2) 20 degrees ≤ Φ2 < 100 degrees (3) T1>T2 (4) 55％≤T1≤95％ (5) 25％＜T2＜80％。 2. The method for manufacturing a photomask according to claim 1, wherein, The transfer pattern also includes a light-blocking portion with an optical density (OD) of 3 or higher for the exposed light.

3. The method for manufacturing a photomask according to claim 2, wherein, In the process of determining the correction area, the correction area is determined as the area where the edge of the correction film is separated from the edge of the light-shielding portion.

4. The method for manufacturing a photomask according to claim 3, wherein, The method for manufacturing the photomask further includes the following steps: forming a supplementary film in such a way that it at least covers the edge of the correction film and the edge of the light-shielding portion, thereby modifying the shape of the correction semi-transparent portion, wherein the supplementary film is composed of a material with a different composition than the light-shielding portion.

5. The method for manufacturing a photomask according to claim 2, wherein, The semi-transparent portion is configured such that it is sandwiched between the light-shielding portion.

6. The method for manufacturing a photomask according to claim 1 or 2, wherein, The composition or physical properties of the first membrane and the second membrane are different from each other.

7. The method for manufacturing a photomask according to claim 1 or 2, wherein, The transmittance Tm of the semi-transparent portion for light of the representative wavelength is 25% < Tm ≤ 80%.

8. The method for manufacturing a photomask according to claim 1 or 2, wherein, The phase shift Φm of the semi-transparent portion for the light representing the wavelength is 160 degrees ≤ Φm ≤ 200 degrees.

9. A photomask having a transfer pattern, the transfer pattern comprising a semi-transparent portion formed by patterning a semi-transparent film formed on a transparent substrate, wherein, The photomask includes a modified semi-transparent portion on which a modified film is locally formed, the modified film comprising a material different from the semi-transparent film. The correction film is a laminated film formed by sequentially stacking a first film and a second film. The first film has a higher transmittance than the semi-transparent film. The second membrane has a transmittance for adjusting the transmittance of the modified membrane. When the transmittance of the first film to the representative wavelength of the exposure light is set to T1 and the phase shift is set to Φ1, and the transmittance of the second film to the representative wavelength is set to T2 and the phase shift is set to Φ2, the following relationships (1) to (5) are satisfied, and the exposure light uses light with a wavelength of 300nm to 500nm: (1) 100 degrees ≤ Φ1 < 200 degrees (2) 20 degrees ≤ Φ2 < 100 degrees (3) T1>T2 (4) 55％≤T1≤95％ (5) 25％＜T2＜80％。 10. The photomask according to claim 9, wherein, The transfer pattern also includes a light-blocking portion with an optical density (OD) of 3 or higher for the exposed light.

11. The photomask according to claim 10, wherein, The edge of the modified semi-transparent portion is separated from the edge of the light-blocking portion.

12. The photomask according to claim 11, wherein, A supplementary film is formed such that it at least covers the edges of the modified semi-transparent portion and the edges of the light-shielding portion, and the supplementary film is composed of a material with a different composition than the light-shielding portion.

13. The photomask according to claim 10, wherein, The semi-transparent portion is arranged such that it is sandwiched between the light-blocking portion.

14. The photomask according to claim 9 or 10, wherein, The composition or physical properties of the first membrane and the second membrane are different from each other.

15. The photomask according to claim 9 or 10, wherein, The transmittance Tm of the semi-transparent portion for light of the representative wavelength is 25% < Tm ≤ 80%.

16. The photomask according to claim 9 or 10, wherein, The phase shift Φm of the semi-transparent portion for the light representing the wavelength is 160 degrees ≤ Φm ≤ 200 degrees.

17. A method for manufacturing a component for a display device, wherein, The manufacturing method of the device for the display device includes the following steps: The process of preparing the photomask as described in claim 9 or 10; and The transfer process involves exposing the photomask to an exposure device to transfer the transfer pattern onto the object to be transferred.

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