TW202041967A - Photomask, method of manufacturing a photomask, and method of manufacturing a display device - Google Patents

Abstract

To provide a method of manufacturing a photomask, which is capable of forming a transfer pattern having a high dimensional accuracy. A method of manufacturing a photomask includes a step of preparing a photomask substrate comprising an optical film and a resist film formed on a transparent substrate in this order, an initial development step of carrying out drawing and development to form a resist pattern on the resist film; a preliminary etching step of etching the optical film with the resist pattern used as a mask to form a preliminary pattern by the optical film, an additional development step of performing additional development for the resist pattern in a state where at least a part of an edge of the preliminary pattern formed by the preliminary etching step is within a region corresponding to the resist pattern, thereby retreating an edge of the resist pattern to expose the edge of the preliminary pattern, a measurement step of measuring a size of a predetermined part of the preliminary pattern, and an additional etching step of determining an additional etching amount on the basis of the size measured in the measurement step and further etching the optical film to form a final pattern.

Description

Photomask, photomask manufacturing method, and display device manufacturing method

The present invention relates to a photomask, a manufacturing method of the photomask, and a manufacturing method of a display device.

With the high-definition of electronic device products such as display devices, the demand for more stringent dimensional control for the transfer patterns of the photomasks used in the manufacture of such devices has increased.

In relation to this, for example, Patent Document 1 describes a method of more accurately controlling the size of the pattern of the light-shielding film. That is, the following method is described in which the resist pattern is used as a mask to etch the light-shielding film, and the light-shielding film not covered by the resist pattern is removed. After the etching is stopped, light is irradiated from the back side of the substrate to prevent The resist that is shielded by the light-shielding film is exposed to light for development, whereby the edge position of the light-shielding film is grasped and the additional etching time is determined.

In addition, for example, Patent Document 2 describes a method for accurately detecting the time point when etching is stopped (end point detection). According to the method described in Patent Document 2, the resist film is processed using pattern data including transfer pattern data for forming the intended transfer pattern and monitoring pattern data for forming the monitor pattern for size measurement. Draw and form a resist pattern. After the optical film is etched for a specific time using this resist pattern as a mask, the size of the monitor pattern is measured, and based on the size, additional etching is performed on the optical film. [Prior technical literature] [Patent literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2010-169750 [Patent Document 2] Japanese Patent Laid-Open No. 2015-191088

[The problem to be solved by the invention]

The level of image quality, brightness, operating speed, and power saving performance required for display devices (liquid crystal display devices, organic EL (Electro-luminescence) display devices, etc.) has never been improved. Under such circumstances, there is a demand for miniaturization and high-density of transfer patterns of photomasks used in the manufacture of display devices.

When manufacturing a display device, a photolithography step is used to manufacture a photomask with a desired transfer pattern. That is, a resist film is formed on an optical film formed on a transparent substrate, the resist film is drawn with energy rays (laser light, etc.) and then developed, and the resist pattern obtained thereby is used as a mask for the optical film Perform etching. If necessary, other optical films are further formed, and the photolithography step is repeated to form the final transfer pattern. The optical film referred to here includes, for example, a light-shielding film that shields the light exposed to the mask, a semi-transmissive film that transmits part of the exposed light, or a functional film such as a phase shift film or an etching stop film.

The size of the photomask for display device manufacturing (for example, a quadrilateral whose main surface is 300 mm or more) is larger than the photomask for semiconductor device manufacturing (generally, one side of the main surface is 5-6 inches), and there are many sizes . Therefore, in the etching of optical films, compared to dry etching that requires a vacuum chamber, when it is adapted to wet etching, there are advantages such as less burden on equipment or steps, and easier control.

On the other hand, there are also difficulties derived from wet etching. In general, dry etching has the properties of anisotropic etching. In contrast, wet etching has stronger properties of isotropic etching in which etching is performed isotropically. Therefore, etching (side etching) is also performed from the side surface of the optical film of the etching target. Fig. 1 is a SEM (Scanning Electron Microscope) photograph showing a state where the side surface of a light-shielding film as an optical film is etched by wet etching. The size of the etched optical film pattern may not necessarily be the same as the size of the resist pattern that becomes the etching mask. At the time point when the etching for a specific time has been implemented, the edge of the optical film pattern has entered the inner side of the edge position of the resist pattern. When viewed from the front side of the resist pattern, the optical film pattern becomes covered by the resist pattern Status, therefore, its size cannot be measured directly. Therefore, it is difficult to determine the end point of etching.

Even if the etching rate (the amount of etching per unit time) can be grasped in order to achieve the desired pattern size, it is not necessarily effective to determine the required etching time only depending on the grasp of the etching rate. For example, when the resist pattern used as an etching mask during wet etching is formed under the influence of variation or unevenness of development conditions such as the development temperature of the resist or the concentration of the developer, it is difficult to keep the development conditions constant.

Furthermore, the edge shape of the resist pattern is formed by drawing, but it is known that the film thickness of the resist pattern or the surface reflectance of the optical film affects drawing conditions. However, it is still not easy to always set the film thickness of the resist pattern or the surface properties of the optical film to a fixed value.

That is, the actual etching process when the optical film is wet-etched cannot avoid factors other than the pure etching rate of the optical film and the etchant, especially the variable factors caused by the resist.

Considering the above-mentioned current situation, in order to perform patterning with high dimensional accuracy, it is not affected by the above-mentioned variable factors, and the accurate etching time until the end of the etching can be grasped (that is, the required remaining etching amount must be etched Time) is more useful.

The method described in Patent Document 1 is to irradiate light from the back surface of the substrate after the light-shielding film is etched, and then develop the resist pattern of the portion not shielded by the light-shielding film. Thereby, the edge position of the resist pattern is consistent with the edge position of the light-shielding film, and the additional etching time is determined by grasping the edge position. According to this method, the edge position of the light-shielding film covered by the resist pattern can be grasped, and therefore, the required additional etching amount, that is, the additional etching time can be obtained.

However, this method is not necessarily effective for meeting the extremely strict dimensional accuracy required by recent display devices. The reason is that, by the method described in Patent Document 1, when developing after irradiating light from the back of the substrate, it is difficult to make the edges of the resist pattern and the edges of the light-shielding film due to uneven development speed in the surface of the mask substrate. Exactly the same. Therefore, in the measurement of the size of the optical film pattern, it is impossible to guarantee whether the size of the optical film has been directly measured, and thus sufficient measurement accuracy cannot be obtained.

In the method described in Patent Document 2, the size of the monitor pattern is directly measured from the front side by partially removing the resist film of the portion where the monitor pattern is formed. Based on the calculation of the size of the monitor pattern, the etching time is added, and the optical film is etched. According to this method, the size of the monitor pattern obtained by patterning the optical film is measured, and therefore, it is not easily affected by the variation factors caused by the resist.

However, the method described in Patent Document 2 is hardly sufficient for obtaining high dimensional accuracy. The reason is that the size measurement of the method described in Patent Document 2 indirectly obtains the size of the transfer pattern that requires size control based on the monitoring pattern, instead of directly measuring the size of the transfer pattern that requires size control. Therefore, the calculation The additional etching time obtained is hardly accurate.

In consideration of the above-mentioned current situation, in order to perform patterning with high dimensional accuracy, it is more beneficial to obtain the following method, which is not easily affected by the change factors caused by the resist, and can still accurately and densely grasp the accuracy until the end of the etching Etching time (ie, etching time suitable for the amount of etching required for the optical film).

As mentioned above, the display devices represented by liquid crystal or organic EL tend to have more finer structures than before. This tendency is common to thin-film transistor (TFT) substrates or color filters (photosensitive spacers, color plates) and other components that are to be obtained by photomasks, which are responsible for driving the display device, and are shared with these The fineness of the image in the display device, the speed of the action, the brightness, and the power saving requirements are related.

As described above, the accuracy requirements of the CD (Critical Dimension: hereinafter, used in the meaning of the pattern width) of the transfer pattern possessed by the mask for manufacturing the display device have become strict. This case is not limited to pattern designs such as line and space patterns, hole patterns, etc., but all are the same. For example, a method that satisfies strict specifications such that the CD accuracy of the transfer pattern becomes a target value of ±50 nm or less, and furthermore, a target value of ±20 nm or less.

The inventor of the present invention focused on the above-mentioned problems and conducted intensive research to make the center value of the CD of the formed transfer pattern coincide with the target value with high accuracy. The purpose of the present invention is to obtain a method for manufacturing a photomask that can form a transfer pattern with high dimensional accuracy. [Technical means to solve the problem]

(First aspect) The first aspect of the present invention is a method for manufacturing a photomask, which is provided with a pattern for transfer on a transparent substrate, and includes the following steps: preparing the above transparent substrate to sequentially form an optical film and The photomask substrate of the resist film; the initial development step, which is to draw and develop the above-mentioned resist film by a drawing device to form a resist pattern; the pre-etching step, which uses the above-mentioned resist pattern as a mask, Perform wet etching on the optical film for a specific time to form a preliminary pattern based on the optical film; an additional development step is performed when at least a part of the edge of the preliminary pattern formed by the pre-etching step is located on the resist pattern In the state in the area, perform additional development on the resist pattern to retreat the edge of the resist pattern to expose the edge of the prepared pattern; the measurement step is to determine the edge position of the prepared pattern The size of the specific part of the preliminary pattern; and the additional etching step, which determines the additional etching amount based on the measured size, and based on the additional etching amount, the optical film is further etched to form a certain pattern including the optical film .

(Second aspect) The second aspect of the present invention is a method of manufacturing a photomask as in the first aspect, wherein in the additional development step, at least one of the composition and the concentration is used relative to the initial development step. Different developers are used.

(Third Aspect) The third aspect of the present invention is a method for manufacturing a photomask as in the first or second aspect, wherein in the additional etching step, the pattern is formed with a specific width near the edge of the determined pattern Film thickness reduction part of film thickness reduction.

(Fourth aspect) The fourth aspect of the present invention is the manufacturing method of the photomask as the third aspect, wherein the above-mentioned specific width is greater than 0 μm and less than 0.8 μm.

(Fifth aspect) The fifth aspect of the present invention is a method for manufacturing a photomask as in any one of the first to fourth aspects, wherein the optical film includes a light-shielding film, and the light-shielding film has Anti-reflective layer.

(Sixth aspect) The sixth aspect of the present invention is a method of manufacturing a photomask as in any one of the first to fourth aspects, wherein the optical film includes a light-shielding film, and after the pre-etching step It includes an additional exposure step that irradiates light from the back side of the transparent substrate to expose a portion of the resist pattern that is not shielded by the light-shielding film.

(Seventh aspect) The seventh aspect of the present invention is a method of manufacturing a photomask as in any one of the above-mentioned first to fifth aspects, wherein the above-mentioned optical film is a light-shielding film, and the above-mentioned photomask substrate is The transparent substrate and the light-shielding film are provided with a semi-transmissive film that transmits a part of the light used in the exposure of the photomask, and the semi-transparent film and the optical film include materials with etching selectivity to each other.

(Eighth aspect) The eighth aspect of the present invention is a method for manufacturing a photomask as in any one of the above-mentioned first to seventh aspects, wherein the above-mentioned photomask substrate is the above-mentioned one that will be formed on the above-mentioned transparent substrate. A photomask intermediate formed by patterning at least a part of an optical film.

(Ninth aspect) The ninth aspect of the present invention is a method of manufacturing a display device, which includes the following steps: preparing a photomask manufactured by the manufacturing method of any one of the first to eighth aspects; And use the exposure device to transfer the above-mentioned transfer pattern to the transfer object.

(Tenth aspect) The tenth aspect of the present invention is a photomask, which is provided with a pattern for transfer on a transparent substrate. The pattern for transfer includes a light-transmitting portion exposing the transparent substrate, and the transparent substrate The non-transmissive part of the optical film is formed thereon, and the non-transmissive part is a film thickness reduction part with a specific width where the thickness of the optical film is locally reduced at the edge portion adjacent to the transparent part, and the specific width More than 0 μm and less than 0.8 μm.

(Eleventh aspect) The eleventh aspect of the present invention is a mask as the tenth aspect, wherein the optical film is a light-shielding film provided with an anti-reflection layer on the surface, and the film thickness reduction part is achieved by At least a part of the anti-reflective layer disappears and is formed.

(Twelfth aspect) The twelfth aspect of the present invention is a method for manufacturing a display device, which includes the following steps: preparing a mask as in the tenth or eleventh aspect; and using an exposure device to apply the transfer The pattern is transferred to the transferred body. [Effects of the invention]

According to the present invention, a method for manufacturing a photomask capable of forming a transfer pattern with high dimensional accuracy can be obtained.

[First Embodiment] The first embodiment of the manufacturing method of the photomask of the present invention will be described with reference to the drawings. 2 is a schematic cross-sectional view illustrating the manufacturing method of the photomask according to the first embodiment of the present invention in the order of steps.

The photomask of the present invention is obtained by applying photolithography to the following photomask substrate, and has a transfer pattern formed by patterning an optical film formed on a transparent substrate. The pattern for transfer may include a light-transmitting part where the transparent substrate is exposed, and a non-light-transmitting part where the optical film is formed. The non-transmissive part may include a light-shielding part and a semi-transmissive part described below.

Furthermore, in this specification, the mask substrate refers to the one with the optical film formed on the main surface of the transparent substrate, and includes the so-called mask base. The photomask substrate also includes a photomask base with resist on which a resist film is formed on the optical film. In addition, the photomask substrate may also be a photomask intermediate formed by patterning a part of the optical film for the purpose of manufacturing a photomask with a film pattern of a laminated structure.

The manufacturing method of the photomask of this 1st Embodiment is demonstrated concretely. <Steps of preparing a photomask substrate> As shown in FIG. 2(a), a photomask substrate 20 is prepared.

(Photomask Substrate) The photomask substrate 20 can be a transparent substrate 21 with a light-shielding film 22 as an example of an optical film and a resist film 23 formed on the light-shielding film 22. The light-shielding film 22 may include a light-shielding layer 22a, and further include an anti-reflection layer 22b described below on the surface of the light-shielding layer 22a.

As the transparent substrate 21 used for manufacturing the mask substrate 20, what is formed by flat and smooth polishing of a transparent material such as synthetic quartz is used. For example, the main surface is a quadrilateral with a side of about 300 mm to 1800 mm, and the thickness is about 5 to 13 mm.

The optical film of the mask substrate 20 is formed on the main surface of the transparent substrate 21 by a well-known film forming method such as a sputtering method. In addition, in this specification, the main surface on the side where the transfer pattern is formed among the two main surfaces of the mask substrate 20 is referred to as the "main surface", and the other main surface is referred to as the "back surface". On the transparent substrate 21, a single optical film may be formed, or a plurality of optical films may be laminated.

The optical film can be set as the light-shielding film 22 (the optical density OD (Optical Density) relative to the exposure light when the mask is used is 2 or more, preferably 3 or more). Alternatively, the optical film may also be a semi-transmissive film that transmits a part of exposed light. At this time, the light transmittance of the semi-transparent film can be set to 5 to 80% based on the light transmittance of the transparent substrate 21 (100%).

Such a semi-transmissive film can be usefully applied to so-called multi-grayscale masks (also called grayscale masks or halftone masks, etc.) or halftone phase shift masks. In this case, the light transmittance of exposure is preferably 20 to 70%, and more preferably 30 to 60%. In addition, the phase shift amount of the semi-transparent film with respect to the above-mentioned exposure light can be preferably set to be 90 degrees or less, and more preferably 60 degrees or less.

Alternatively, when the semi-transparent film is applied to the halftone phase shift mask, the light transmittance of the exposure is preferably 5-40%, and more preferably 5-30%. Moreover, the phase shift amount of the semi-transparent film with respect to the above-mentioned exposure light is preferably set within the range of 180±20 degrees.

The thickness of the optical film is determined according to its function, but it is preferably 5 to 250 nm. For example, if the optical film is the light-shielding film 22, the film thickness can be 50 to 200 nm.

The optical film is preferably one capable of wet etching. The material of the optical film may include chromium (Cr), for example. When the optical film is the light-shielding film 22, chromium or its compound can be used, and when the optical film is a semi-transparent film, a chromium compound can be preferably used. As the chromium compound, for example, a film containing any one of chromium oxide, nitride, carbide, oxynitride, and oxycarbonitride may be used.

Furthermore, when the optical film is the light-shielding film 22 or the semi-transparent film, metals other than chromium, such as molybdenum (Mo), tantalum (Ta), tungsten (W), zirconium (Zr), and niobium ( Nb), titanium (Ti), or its compound materials. For example, it may also be a material containing metal silicide or its oxide, nitride, carbide, oxynitride, or carbonitride. As examples of metal silicides that can be used as the material of the above-mentioned optical film, there are molybdenum silicide and tantalum silicide. Moreover, these materials may be used individually by 1 type, and may be used in combination of 2 or more types.

When the optical film is the light-shielding film 22, it is preferable to have an anti-reflection layer 22b for suppressing light reflectivity on the surface. In this case, for example, the anti-reflection layer 22b disposed on the surface of the light-shielding film 22 mainly composed of chromium can be made of a chromium compound (oxide, nitride, carbide, etc.). The anti-reflection layer 22b can be formed by changing the composition in the thickness direction of the light shielding film 22 including the anti-reflection layer 22b. Furthermore, the composition change can be a phased change or a slow change. The anti-reflection layer 22b has the function of suppressing the reflection of the drawing light during the manufacturing process of the photomask, and also has the function of suppressing the reflection of the light exposed when the photomask is exposed, but also has the function of suppressing the surface during the following size measurement The role of reflection. The thickness of the anti-reflective layer 22b can be set to 20-40 nm, for example.

Furthermore, as shown in FIG. 2(a), in the following description of the first embodiment, a case where a light-shielding film 22 (having an anti-reflection layer 22b on the surface) is used as an optical film is taken as an example.

(Resist Film) As the photomask substrate 20 used in the manufacturing method of the photomask of the first embodiment, a resist film 23 formed on the light shielding film 22 can be used. The resist used as the raw material of the resist film 23 can be coated on the light-shielding film 22 by a well-known coating device such as a slit coater or a spin coater. The thickness of the resist film 23 is preferably 300 to 1000 nm.

In addition, here, the resist film 23 is described as a positive photoresist for laser drawing. However, a negative photoresist may also be used, and further, when drawing with an electron beam, a resist for an electron beam may also be used.

Furthermore, in the manufacturing method of the photomask of this 1st Embodiment, the pattern data for drawing with respect to the resist film 23 is prepared. The drawing pattern data is designed based on, for example, the required transfer pattern.

<Initial development step> As shown in FIG. 2(b), the resist film 23 of the prepared photomask substrate 20 is drawn using pattern data for drawing. As the drawing device used, for example, a laser drawing machine can be used. As the laser light, for example, light with a wavelength of about 413 nm can be used.

Then, as shown in FIG. 2(c), the resist film 23 is developed (initial development), thereby forming a resist pattern. This resist pattern functions as an etching mask when etching the light-shielding film 22. The developer can select an appropriate developer according to the composition of the resist film 23. As the developer, for example, a known developer such as TMAH (tetramethylammonium hydroxide) or KOH (potassium hydroxide) aqueous solution can be used.

<Pre-etching step> As shown in FIG. 2(d), the pre-etching of the light-shielding film 22 using the resist pattern as a mask is performed for a specific time. Thereby, a preliminary pattern including the light-shielding film 22 is formed. Here, wet etching is applied.

The etchant (etching solution) can be selected according to the composition of the optical film (here, the light-shielding film 22). For example, in the case of a chromium-based light-shielding film, an etching solution containing an aqueous solution of cerium ammonium nitrate can be used.

The etching solution first acts on the surface of the light-shielding film 22 that is not covered by the resist pattern, whereby the light-shielding film 22 of this part starts to dissolve. Subsequently, with the elution of the light-shielding film 22 in the portion not covered by the resist pattern, the side surface of the light-shielding film 22 is also etched (side etching) by isotropic etching. As a result, as shown in Figure 2(d), it is not uncommon that the edge of the prepared pattern enters more inside than the edge of the resist pattern (that is, within the area of the resist pattern), and its position cannot be recognized from the front side. .

However, the time required for etching until the etching is stopped can be determined in advance according to the design of the transfer pattern to be obtained. The time required for the etching can be calculated by the etching rate based on the combination of the material of the light-shielding film 22 and the etching solution, the film thickness of the light-shielding film 22, and the like. However, due to the above reasons, even if the etching time calculated based on the etching rate is used, the CD accuracy of the resulting transfer pattern cannot be sufficiently satisfied.

Therefore, in the pre-etching of the first embodiment, the light-shielding film 22 starts to dissolve, and after the light-shielding film 22 is removed in the thickness direction, the pre-etching is stopped with an etching time shorter than the etching time calculated in advance. That is, the pre-etching is completed in a state where the opening size of the light-shielding film 22 formed by the pre-etching is lower than the target size. For example, the pre-etching time can be set to about 30 to 120 seconds.

At the end of the pre-etching, at least a part of the edge of the preliminary pattern including the light shielding film 22 is located on the inner side of the edge of the resist pattern as described above, so that it cannot be seen from the main surface side of the mask substrate 20.

In the above-mentioned pre-etching step, the surface of the resist pattern in contact with the etching solution may be deteriorated to form the insoluble layer 24. Therefore, before the following additional development, a treatment of removing the insoluble layer 24 by ozone water treatment or plasma ashing may be performed (FIG. 2(e)).

<Additional development step> As shown in FIG. 2(f), the resist pattern is additionally developed.

In the initial development stage, the resist film 23 that reacts by the light energy of the drawing (sensitization) is eluted by development to form a resist pattern, but the edge of the resist pattern is not sufficiently exposed to the threshold of development. The amount of light exposure. It can be considered that the insufficient exposure is generated along the edge of the resist pattern with a substantially constant width. Therefore, the resist pattern can be further developed under the same or different conditions as the initial development, so that the edge of the resist pattern is set back by the above-mentioned size (that is, the resist pattern is made transparent when viewed from the front side). The adjacent portion of the exposed portion of the substrate 21 partially disappears in the width direction). Thereby, the edge of the prepared pattern can be exposed from the back edge of the resist pattern. In addition, although not necessarily shown in the drawings, in the additional development step, the film thickness of the resist film 23 decreases from the front side at the same time as the edge of the resist pattern recedes. In consideration of this aspect, when the back-off (μm) of the edge of the resist pattern is more than 0 μm and 0.8 μm or less, preferably 0.05 μm or more and 0.4 μm or less, and more preferably 0.1 μm or more and 0.3 μm or less, the resist The film 23 can sufficiently maintain the function of protecting the light-shielding film 22, so that the effect of the first embodiment is obvious. The edge portion of the preliminary pattern located under the resist pattern can be made to be greater than 0 μm and less than 0.8 μm, preferably 0.05 μm or more and 0.4 μm or less, and more preferably 0.1 μm or more by retreating the edge of the resist pattern. The width below 0.3 μm is exposed. In addition, in this specification, the main surface side of the mask is set to upper, and the back side is set to lower.

The developer used in the additional development is the same as the initial development. For example, a known developer such as TMAH (tetramethylammonium hydroxide) or KOH (potassium hydroxide) aqueous solution can be used. It is preferable that the developer used in the additional development has a different composition and/or concentration from the developer used in the initial development. For example, in the case of additional development, the development speed for the same resist is higher than the developer used in the initial development. Thereby, it is possible to efficiently remove the vicinity of the edge of the resist pattern that generates insufficient reaction during drawing.

Moreover, near the edge of the pre-etched resist pattern, as shown in FIG. 3(a), a gap is generated between the resist pattern and the transparent substrate 21 due to side etching of the light shielding film 22 forming the preliminary pattern. During additional development, the developer enters the gap, and therefore, near the edge of the resist pattern (refer to the circle of the dotted line shown in Figure 3(a)), as illustrated by the arrow in Figure 3(a), the resist film 23 The development is performed not only from the side surface, but also from the surface facing the transparent substrate 21 (the surface on the lower side). That is, the resist film 23 is not only eluted from the side surface, but also eluted from the surface facing the transparent substrate 21. Therefore, the edge of the resist pattern can be efficiently retracted, and the edge 27 of the preliminary pattern can be exposed (FIG. 3(b)).

As described above, the film thickness of the resist film 23 is reduced from the front side by additional development. In consideration of this situation, a resist film thickness that does not hinder the function of the protective light shielding film 22 is applied in advance. This is also the case in the following second embodiment and third embodiment.

<Measurement steps of the size of the preliminary pattern> Then, as shown in Figure 2(g), detect the edge position of the preliminary pattern. With this, the size of the preliminary pattern can be measured. For example, if it is a line and space pattern, the size of the line part or the size of the space part can be measured (for example, CD1 in Fig. 2(g)). Here, as an example of the size of the preliminary pattern, the size CD1 of the partition portion, that is, the portion where the transparent substrate 21 is exposed is measured.

The position of the edge of the preparation pattern can be grasped by, for example, irradiating inspection light (for example, light in a wavelength range of 400-600 nm) from the back side or main surface side of the mask substrate 20 and detecting transmitted light or reflected light.

<Calculation of additional etching time> As described above, the size CD1 of the preliminary pattern is measured from the position of the edge of the preliminary pattern. Next, the difference between the measured size CD1 of the prepared pattern and the size of the target interval width of the part is obtained, and the undercut amount (additional etching amount) is calculated. Then, based on the calculated undercut amount, the additional etching time is calculated by the etching rate obtained in advance.

In this way, in the first embodiment, the size of the resist pattern is not used, but the edge position of the prepared pattern obtained by the detection and the target size and etching rate of the transfer pattern to be obtained are used to calculate the additional etching time. As a result, the required additional etching time can be accurately calculated.

<Additional etching step> As shown in FIG. 2(h), additional etching is performed with the additional etching time obtained as described above. Thereby, a certain pattern including the light shielding film 22 is formed. The additional etching is preferably wet etching. The etching solution may be the same as the etching solution used in the pre-etching step. Alternatively, at least one of composition and concentration may be different from the etching solution used in the pre-etching step. For example, when performing additional etching, a concentration greater than or less than the etching solution used for pre-etching can be used. In the additional etching step, it is preferable that the etching speed for the same light-shielding film is lower than the etching solution used in the pre-etching step. For example, the etching rate of the etching solution used in the additional etching can be set to about 1/6 to 1/4 of the etching rate of the etching solution used in the pre-etching with respect to the same light-shielding film.

In the additional etching step, as shown in FIG. 4, the film thickness of a part of the light-shielding film 22 in the edge portion of the determined pattern may be reduced from the front side to form a film thickness reduction portion 28, but it does not function as a mask. cause problems. For example, when the light-shielding film 22 is provided with the anti-reflection layer 22b, a part of the anti-reflection layer 22b in the edge portion of the certain pattern including the light-shielding film 22 disappears from the front side, thereby forming a film thickness reduction portion 28 of a specific width . However, the width is extremely small and is only a negligible part of the anti-reflection layer 22b. Therefore, the reflection of the exposure light in this part does not hinder the transferability of the transfer pattern. The aforementioned specific width may be, for example, greater than 0 μm and 0.8 μm or less, preferably 0.05 μm or more and 0.4 μm or less, and more preferably 0.1 μm or more and 0.3 μm or less. The same applies to the following second embodiment and third embodiment.

Moreover, even if a part of the light-shielding film 22 is slightly damaged, its optical performance can be maintained, so there is no problem. The so-called optical performance means that the optical density (OD) of the exposed light is 2 or more, preferably 3 or more. The same applies to the following second embodiment and third embodiment. Furthermore, it may happen that the width of the aforementioned film thickness reduction portion 28 is slightly uneven in the mask surface, but this aspect will not have any influence on the transferability of the mask.

<Resist pattern peeling step> As shown in FIG. 2(i), after the additional etching for the additional etching time is completed, the etching is stopped again, and the resist pattern is peeled.

With the above, the mask provided with the pattern for transfer including the light-transmitting portion 30 and the light-shielding portion 35 is completed (refer to FIG. 2(i)). According to the first embodiment, for example, it is possible to finely control the size so that the size CD2 of the light-transmitting portion 30 coincides with the size of the target interval width. Furthermore, in the above-mentioned first embodiment, the measurement of the size of the preliminary pattern (CD1) is performed only once, but the measurement of the size of the preliminary pattern and additional etching may be repeated as needed, and this aspect is also included in the present invention .

As described above, according to the manufacturing method of the photomask of the first embodiment, the etching time can be calculated based on the size of the preliminary pattern including the light-shielding film 22, not based on the size of the resist pattern. Therefore, even if there are various changes in the formation of the resist pattern used as the etching mask, the size of the finally formed transfer pattern can be accurately matched to the target value. According to the first embodiment, in particular, the dimensional accuracy of the light shielding portion 35 adjacent to the light transmitting portion 30 can be extremely improved.

Furthermore, according to the present invention, the size of the preliminary pattern can be grasped finely and densely by a simple method such as additional development. Therefore, while suppressing the increase in the number of steps and the cost, the center value of the CD of the formed transfer pattern can be made to coincide with the target value with high accuracy.

In the above-mentioned first embodiment, the configuration of manufacturing a photomask using a photomask substrate formed by forming a single film as an optical film on a transparent substrate has been described as an example, but the present invention is not limited to this. Next, the case of manufacturing a photomask using a photomask substrate formed by forming a plurality of films on a transparent substrate will be described.

[Second Embodiment] Fig. 5A is a schematic cross-sectional view illustrating the manufacturing method (a to j) of the mask according to the second embodiment of the present invention in the order of steps. 5B is a schematic cross-sectional view illustrating the manufacturing method (k to s) of the mask of the second embodiment in the order of steps following FIG. 5A. Hereinafter, FIGS. 5A and 5B are collectively referred to as FIG. 5. In this second embodiment, it is possible to manufacture a multi-gray-scale photomask with a transfer pattern including a light-transmitting part, a semi-light-transmitting part, and a light-shielding part. The transfer pattern further includes a part where the light-transmitting part is adjacent to the light-shielding part and a part where the light-shielding part is adjacent to the semi-light-transmitting part. Furthermore, the so-called semi-transmissive part refers to a part that exposes the following semi-transparent film formed on a transparent substrate.

As shown in FIG. 5(a), a mask substrate 20 is prepared. In the manufacturing method of the photomask of the second embodiment, as an example, a transparent substrate 21 is used in which a translucent film 25, a light shielding film 22 including a light shielding layer 22a and an anti-reflection layer 22b, and a resist film 23 are sequentially laminated on a transparent substrate 21 Mask substrate 20. The mask substrate 20 of the second embodiment has the same structure as the mask substrate 20 of the first embodiment, except that it has the semi-transparent film 25.

(Semi-transmissive film) The translucent film 25 in the second embodiment is compared with the light-transmitting portion formed by exposing the transparent substrate 21, and may include, for example, a translucent film that transmits 20 to 80% of light. It is a material with properties and resistance to etching liquid for chromium. The semi-transparent film 25 may also include molybdenum silicide (MoSi) containing molybdenum (Mo) and silicon (Si), for example. The semi-transparent film 25 preferably has etching selectivity with respect to the light shielding film 22.

In the manufacturing method of the photomask of this 2nd Embodiment, from the process of preparing a photomask to the process of peeling a resist pattern, unless there is a special description, it is the same as that of 1st Embodiment. In the drawings, Figures 5(a) to 5(i) correspond to Figures 2(a) to 2(i).

First, as shown in FIG. 5(a), a mask substrate 20 is prepared. The resist film 23 is drawn by drawing pattern data (FIG. 5(b)), and as shown in FIG. 5(c), the resist film 23 is developed, thereby forming a resist pattern (initial development step) . The drawing pattern data used in the initial development step is data designed based on the required transfer pattern, and may be, for example, drawing pattern data for the resist film 23 for forming the light-transmitting portion.

Then, as shown in FIG. 5(d), using the resist pattern as a mask, the light-shielding film 22 is pre-etched for a specific time to form a preliminary pattern including the light-shielding film 22 (pre-etching step). Furthermore, in the pre-etching step in the first embodiment, the transparent substrate 21 is exposed, but in the second embodiment, the semi-transparent film 25 is exposed.

In the case where the insoluble layer 24 is formed in the above-mentioned pre-etching step, the insoluble layer 24 may be removed by ozone water treatment or plasma ashing before the following additional development in the same manner as in the first embodiment ( Figure 5(e)).

Then, as shown in FIG. 5(f), the resist pattern is additionally developed to retreat the edge of the resist pattern (the part of the resist pattern adjacent to the exposed part of the semi-transparent film 25 when viewed from the front side is Partially disappeared in the width direction), thereby exposing the edge of the preliminary pattern (additional development step). The amount of recession (μm) of the edge of the resist pattern and the width (μm) of the edge portion of the exposed preliminary pattern can be set to be the same as the additional development step in the first embodiment, respectively.

Furthermore, as shown in FIG. 5(g), the position of the edge of the preliminary pattern is detected, thereby measuring the size of the preliminary pattern (the step of measuring the size of the preliminary pattern). For example, the size CD3 of the part where the semi-transparent film 25 is exposed is measured.

Since the semi-transmissive film 25 partially transmits light, for example, by irradiating inspection light from the back side or the main surface side of the mask substrate 20 and detecting the transmitted light, the edge of the preliminary pattern can be detected. With this, the preliminary pattern size CD3 can be measured. The additional etching time (calculation of additional etching time) can be calculated based on the difference between the preliminary pattern size CD3 and the target interval width.

As shown in FIG. 5(h), additional etching is performed with the obtained additional etching time to form a definite pattern including the light-shielding film 22 (additional etching step). At the edge portion of the defined pattern, the film thickness reduction portion 28 of a specific width is formed in the same manner as in the first embodiment.

As shown in Fig. 5(i), the resist pattern is peeled off (the step of peeling off the resist pattern).

<Etching of semi-transmissive film> Then, as shown in FIG. 5(j), the semi-transmissive film 25 is etched using a certain pattern including the light-shielding film 22 as a mask. Thereby, the light transmitting portion 40 is formed. When the translucent film 25 includes molybdenum silicide (MoSi), for example, etching can be performed by supplying a fluorine (F)-based wet etching solution (or etching gas) to the translucent film 25. In this way, it is possible to finely control the size so that the size CD4 of the light-transmitting portion 40 coincides with the size of the target interval width.

After the etching of the translucent film 25, the initial development step, the pre-etching step, the additional development step, the measurement step of the preliminary pattern size, the calculation of the additional etching time, the additional etching step, and the peeling step of the resist pattern are repeated. Thereby, a semi-transparent part can be formed. Each step is described in detail below.

<Initial development step> As shown in FIG. 5(k), a new resist film 26 is applied. Furthermore, the resist film 26 is drawn using the drawing pattern data prepared in advance (FIG. 5(l)) and developed, thereby forming a resist pattern (FIG. 5(m)). The drawing device and developer can be the same as those used in the initial development step of the first embodiment.

The above-mentioned drawing pattern data is data designed based on the required transfer pattern, and may be, for example, drawing pattern data for the resist film 26 for forming a semi-transmissive portion.

<Pre-etching step> Then, as shown in FIG. 5(n), the resist pattern is used as a mask, and the light-shielding film 22 is pre-etched for a specific time. Thereby, a preliminary pattern including the light-shielding film 22 is formed. Here, wet etching is applied. As the etchant (etching solution), the same etchant used in the pre-etching step of the first embodiment can be used. In addition, the end point of the pre-etching in this second embodiment can be determined in the same way as the pre-etching step in the first embodiment.

In the pre-etching step, when the insoluble layer 29 is formed on the surface of the resist pattern in contact with the etching solution, the insoluble layer may be treated by ozone water treatment or plasma ashing before additional development. 29 removal processing (Figure 5(o)).

<Additional development step> As shown in FIG. 5(p), the resist pattern is additionally developed. Thereby, the edge of the resist pattern can be retreated at a fixed size, and the edge of the preliminary pattern adjacent to the exposed portion of the semi-transparent film 25 is exposed. The amount of recession (μm) of the edge of the resist pattern and the width (μm) of the edge portion of the exposed preliminary pattern can be set to be the same as the additional development step in the first embodiment, respectively.

As the developer used in the additional development, the same developer used in the additional development of the first embodiment can be used. Furthermore, the developer used in the additional development of the second embodiment is preferably a developer having a different composition and/or concentration from the developer used in the initial development of the second embodiment. For example, in the case of additional development, the development speed for the same resist can be applied which is faster than the developer used in the initial development. Thereby, it is possible to efficiently remove the vicinity of the edge of the resist pattern that generates an insufficient response during drawing.

<Measurement steps of the size of the preliminary pattern> Next, as shown in FIG. 5(q), the position of the edge of the preliminary pattern adjacent to the exposed portion of the semi-transparent film 25 is detected. Since the semi-transmissive film 25 partially transmits light, for example, the position of the edge of the preliminary pattern can be detected by irradiating inspection light from the back side or the main surface side of the mask substrate 20 and detecting the transmitted light. With this, the size of the preliminary pattern can be measured. Here, as an example of the size of the preliminary pattern, the size of the exposed portion of the translucent film 25 (CD5 in FIG. 5(q)) is measured.

<Calculation of additional etching time> As described above, the size CD5 of the preliminary pattern is measured according to the edge position of the preliminary pattern. The difference between the measured size CD5 of the preliminary pattern and the size of the target semi-transmissive part is calculated, and the amount of side etching (additional etching amount) is calculated. Then, based on the calculated undercut amount, an additional etching time is calculated using the previously calculated etching rate.

<Additional etching step> As shown in FIG. 5(r), additional etching is performed with the additional etching time obtained as described above. Thereby, a certain pattern including the light-shielding film 22 is formed. At the edge portion of the defined pattern, similar to the first embodiment, a film thickness reduction portion 28 of a specific width is formed. The additional etching is preferably wet etching. The etchant (etching liquid) can be the same as the additional etching in the first embodiment.

<Resist pattern peeling step> As shown in FIG. 5(s), after the additional etching for the additional etching time is completed, the etching is stopped again, and the resist pattern is peeled. In this way, the size can be finely and densely controlled in such a way that the size CD6 of the semi-transmissive portion 45 coincides with the size of the target semi-transmissive portion.

With the above, a multi-gray-scale photomask with a transfer pattern including the light-transmitting portion 40, the semi-transmitting portion 45, and the light-shielding portion 50 is completed (see FIG. 5(s)). In the second embodiment, the size measurement of the preliminary pattern and additional etching may be repeated as needed, and this aspect is also included in the present invention. Furthermore, in this second embodiment, as an example, after forming the light-transmitting portion 40 (FIG. 5(j)), a new resist film 26 is applied, and photolithography is repeated to form the semi-light-transmitting portion 45. The structure is explained, but it is not limited to this. For example, the configuration of forming the translucent portion 40 after forming the semi-transmissive portion 45 is also included in the second embodiment.

In this second embodiment, the same effects as in the first embodiment can also be obtained. In the multi-gray mask of the second embodiment, in particular, the dimensional accuracy of the light-shielding part 50 adjacent to the light-transmitting part 40 or the semi-light-transmitting part 45 and the semi-light-transmitting part 45 adjacent to the light-shielding part 50 becomes extremely high. high.

[Third Embodiment] Next, referring to Fig. 6, the third embodiment of the present invention will be described. Fig. 6 is a schematic cross-sectional view illustrating the manufacturing method of the mask of the third embodiment in the order of steps. The manufacturing method of the photomask of the third embodiment is that before the additional development in the first embodiment, light is irradiated from the back side of the photomask substrate 20 to expose the resist pattern of the portion not shielded by the light shielding film 22 Step (additional exposure step).

As shown in FIG. 6(a), a mask substrate 20 is prepared. The mask substrate 20 of the third embodiment may have the same structure as the mask substrate 20 of the first embodiment. The manufacturing method of the photomask of the third embodiment is the same as that of the first embodiment except that it has an additional exposure step before the additional development step (FIG. 2(f)) of the first embodiment. In the drawings, Figs. 6(a) to 6(e) correspond to Figs. 2(a) to 2(e). Therefore, the flow after the additional exposure step (after FIG. 6(f)) will be described.

<Additional exposure step> After forming a preliminary pattern and removing the insoluble layer 24 of the resist film 23 if necessary (Figure 6(e)), as shown in Figure 6(f), irradiate from the back side of the mask substrate 20 The light exposes the resist pattern of the portion not shielded by the light shielding film 22. The part that is not shielded by the light-shielding film 22 refers to the part of the resist pattern that can be seen from the back side of the mask substrate 20, or the edge of the preliminary pattern adjacent to the exposed part of the transparent substrate 21 in the resist pattern. A part of the transparent substrate 21 protruding from the exposed part side. As the light for exposure in the additional exposure step, for example, light with a wavelength of about 413 nm can be used.

<Additional development> As shown in Figure 6(g), perform additional development on the resist pattern so that the edges of the resist pattern recede by a fixed size. Thereby, the edge of the preliminary pattern adjacent to the exposed portion of the transparent substrate 21 can be exposed. The amount of recession (μm) of the edge of the resist pattern and the width (μm) of the edge portion of the exposed preliminary pattern can be set to be the same as the additional development step in the first embodiment, respectively.

The developer used in the additional development can be the same as the developer used in the additional development of the first embodiment. In the third embodiment, the resist pattern is additionally exposed. Therefore, the edge vicinity of the resist pattern adjacent to the exposed portion of the transparent substrate 21 when viewed from the front can be removed more efficiently.

<Measurement steps of the size of the preliminary pattern> Then, as shown in Figure 6(h), detect the position of the edge of the preliminary pattern. With this, the size of the preliminary pattern can be measured. For example, if it is a line and space pattern, the size of the line part or the size of the space part can be measured (for example, CD7 in Fig. 6(h)). Here, as an example of the size of the preliminary pattern, the size CD7 of the partition portion, that is, the portion where the transparent substrate 21 is exposed is measured. The additional etching time can be calculated based on the difference between the preliminary pattern size CD7 and the target gap width. The position of the edge of the preliminary pattern can be grasped by the same method as in the first embodiment.

<Calculation of additional etching time> As described above, the size CD7 of the preliminary pattern is measured according to the position of the edge of the preliminary pattern. Then, the difference between the measured size CD7 of the prepared pattern and the size of the target interval width of the part is obtained, and the undercut amount (additional etching amount) is calculated. Then, based on the calculated undercut amount, the additional etching time is calculated using the etching rate obtained in advance.

In this way, in the third embodiment, the size of the resist pattern is not used, but the edge position of the prepared pattern obtained by the detection and the target size and etching rate of the transfer pattern to be obtained are used to calculate the additional etching time. As a result, the required additional etching time can be accurately calculated.

<Additional Etching> As shown in FIG. 6(i), additional etching is performed with the additional etching time obtained as described above. Thereby, a certain pattern including the light-shielding film 22 is formed. At the edge portion of the defined pattern, similar to the first embodiment, a film thickness reduction portion 28 of a specific width is formed. The additional etching is preferably wet etching. The etchant (etching liquid) can be the same as in the first embodiment.

<Peeling of the resist pattern> Then, as shown in FIG. 6(j), after the additional etching for the additional etching time is completed, the etching is stopped again, and the resist pattern is peeled off.

With the above, the mask provided with the pattern for transfer including the light-transmitting portion 55 and the light-shielding portion 60 is completed (see FIG. 6(j)). According to the third embodiment, for example, it is possible to finely control the size so that the size CD8 of the light-transmitting portion 55 coincides with the size of the target interval width. Furthermore, in the above aspect, the size measurement of the preliminary pattern is only performed once, but the size measurement and additional etching of the preliminary pattern may be repeated as needed, and this aspect is also included in the present invention.

In the third embodiment of the present invention, a configuration of manufacturing a mask using a mask substrate in which a single film is formed on a transparent substrate as an optical film has been described as an example, but the present invention is not limited to this. According to the third embodiment, for example, as in the second embodiment, a mask substrate 20 formed by sequentially layering a semi-transparent film 25, a light-shielding film 22, and a resist film 23 (26) can be used to produce a mask substrate 20 including Multi-gray-scale photomask for transfer patterns of light-transmitting part, semi-transmitting part and shading part. Also in this case, the additional exposure step of the third embodiment may be implemented before additional development. In this third embodiment, the same effects as in the first embodiment can also be obtained.

The use of the photomask of the manufacturing method of the present invention is not particularly limited. The photomask of the manufacturing method of the present invention can be advantageously used as a photomask for manufacturing display devices. For example, the photomask of the manufacturing method of the present invention can be advantageously used in various layers used in display devices (for example, the source/drain layer of a TFT array, the pixel layer or the photosensitive spacer layer of a color filter, etc.). Especially important layer) formation.

The present invention includes a manufacturing method of a display device using the photomask of the above-mentioned manufacturing method of the present invention. For example, the manufacturing method of the display device of the present invention may include the steps of: preparing a photomask manufactured by the manufacturing method of the first embodiment, the second embodiment, or the third embodiment of the present invention; and using an exposure device to The photomask is exposed, and the transfer pattern is transferred to the transfer target body. According to the manufacturing method of the display device of the present invention, the display device can be manufactured using a mask that can control the precision of fine and dense pattern size. Therefore, it can be applied to the manufacture of display devices under a finer design. Contribute to the improvement of production efficiency or yield.

For example, when the photomask of the present invention is used to manufacture a display device, the transfer pattern has a line width of about 0.8-100 μm, and when the portion of 0.8-30 μm is used as the mask for the size measurement, this The effect of the invented photomask manufacturing method is particularly obvious. Therefore, as an exposure machine used to transfer the transfer pattern of the photomask manufactured by the manufacturing method of the present invention to the transfer object, it can be used as a so-called LCD (Liquid Crystal Display) or FPD (Flat Panel Display) is a projection exposure device or proximity exposure device with the same magnification as the exposure device for display devices. At this time, the light for exposure depends on the light source of the exposure device used in the mask exposure. Single wavelength light such as i-line, h-line or g-line can be used, or a specific wavelength region (such as 365-436 nm or 300～365 nm etc.) light. As the optical system of the above-mentioned exposure device, in the case of the projection exposure device, a NA (numerical aperture) of 0.08 to 0.15 and a value of the coherence factor (σ) in the range of 0.5 to 0.9 can be preferably used.

The photomask manufacturing method of the present invention can be preferably applied, for example, when an optical film is used as a light shielding film to manufacture a binary photomask. In addition, the method for manufacturing a photomask of the present invention can also be applied to form a multi-gray-level photomask including a light-transmitting portion, a light-shielding portion, and a translucent portion using a translucent film in the transfer pattern. In this case, a semi-transparent film is made by using a film that partially transmits (transmittance, for example, 20-60%) without phase inversion of the exposed light (phase shift is 90 degrees or less) as a semi-transparent film Guangbe. The formed transfer pattern can form a resist pattern with a stepped three-dimensional shape on the transferred body, so that the efficiency of the manufacture of display devices and the like can be realized.

The present invention has been specifically explained with respect to the first to third embodiments, but the technical scope of the present invention is not limited to the above-mentioned embodiments, and various changes can be made without departing from the spirit thereof.

20: Mask substrate 21: Transparent substrate 22: Light-shielding film 22a: Light-shielding layer 22b: Anti-reflection layer 23: Resist film 24: Insoluble layer 25: Semi-transmissive film 26: Resist film 27: Edge of preliminary pattern 28 : Film thickness reduction part 29: Insoluble layer 30: Light-transmitting part 35: Light-shielding part 40: Light-transmitting part 45: Semi-light-transmitting part 50: Light-shielding part 55: Light-transmitting part 60: Light-shielding part CD1: size CD2: size CD3: size CD4: size CD5: size CD6: size CD7: size CD8: size

FIG. 1 is an example of an SEM photograph of the cross-sectional shape of an optical film pattern (light-shielding film pattern) after wet etching with a resist pattern as an etching mask. 2(a) to (i) are schematic cross-sectional views illustrating the manufacturing method of the photomask according to the first embodiment of the present invention in the order of steps. Figures 3(a) and (b) are schematic cross-sectional views illustrating an additional development near the edge of the resist pattern of the embodiment of the present invention. Fig. 4 is a schematic cross-sectional view illustrating the film thickness reduction portion of the mask according to the embodiment of the present invention. FIG. 5A is a schematic cross-sectional view illustrating the manufacturing method (a to j) of the photomask according to the second embodiment of the present invention in the order of steps. 5B is a schematic cross-sectional view illustrating the manufacturing method (k to s) of the photomask according to the second embodiment of the present invention in the order of steps. 6(a) to (j) are schematic cross-sectional views illustrating the manufacturing method of the mask according to the third embodiment of the present invention in the order of steps.

20: Mask substrate

21: Transparent substrate

22: Shading film

22a: shading layer

22b: Anti-reflective layer

23: resist film

24: Insoluble layer

30: Translucent part

35: Shading part

CD1: size

CD2: size

Claims (12)

A method for manufacturing a photomask, which is provided with a transfer pattern on a transparent substrate, and includes the following steps: preparing a photomask substrate with an optical film and a resist film sequentially formed on the transparent substrate; an initial development step, which is The above-mentioned resist film is drawn by using a drawing device and developed to form a resist pattern; the pre-etching step is to use the above-mentioned resist pattern as a mask and perform wet etching on the above-mentioned optical film for a specific period of time to form a base The preparation pattern of the above-mentioned optical film; an additional development step, which is to perform an additional development step on the above-mentioned resist pattern in a state where at least a part of the edge of the above-mentioned preliminary pattern formed by the above-mentioned pre-etching step is located in the region of the above-mentioned resist pattern Develop to retreat the edge of the above-mentioned resist pattern and expose the edge of the above-mentioned preliminary pattern; The measurement step is to measure the size of the specific part of the above-mentioned preliminary pattern by grasping the edge position of the above-mentioned preliminary pattern; and Add an etching step, which The additional etching amount is determined based on the measured size, and based on the additional etching amount, the optical film is further etched to form a definite pattern including the optical film. The method for manufacturing a photomask according to claim 1, wherein in the additional development step, at least one of composition and concentration is used with a developer that is different from the developer applied in the initial development step. The method for manufacturing a photomask according to claim 1 or 2, wherein in the additional etching step, a film thickness reduction portion having a film thickness reduction is formed with a specific width near the edge of the predetermined pattern. The method for manufacturing a photomask of claim 3, wherein the above-mentioned specific width is greater than 0 μm and less than 0.8 μm. The method for manufacturing a photomask of claim 1 or 2, wherein the optical film includes a light-shielding film, and the light-shielding film is provided with an anti-reflection layer on the surface. For example, the method for manufacturing a photomask of claim 1 or 2, wherein the above-mentioned optical film includes a light-shielding film, and after the above-mentioned pre-etching step, an additional exposure step is included. The additional exposure step is to irradiate light from the back side of the above-mentioned transparent substrate to The portion of the resist pattern that is not shielded by the light shielding film is exposed. Such as the manufacturing method of the photomask of claim 1 or 2, wherein the above-mentioned optical film is a light-shielding film, The mask substrate is provided with a semi-transmissive film between the transparent substrate and the light-shielding film, which transmits part of the light used in the exposure of the mask, and the semi-transparent film and the optical film include mutual etching Selective materials. The method for manufacturing a photomask of claim 1 or 2, wherein the photomask substrate is a photomask intermediate formed by patterning at least a part of the optical film formed on the transparent substrate. A method of manufacturing a display device, which includes the following steps: preparing a photomask manufactured by the manufacturing method of any one of claims 1 to 8; and using an exposure device to transfer the above-mentioned transfer pattern to a transfer object on. A photomask, which is provided with a pattern for transfer on a transparent substrate, the pattern for transfer includes a light-transmitting portion where the transparent substrate is exposed, and a non-light-transmitting portion on which an optical film is formed on the transparent substrate. The non-transmissive portion is a film thickness reduction portion having a specific width at which the film thickness of the optical film is locally reduced at the edge portion adjacent to the translucent portion, and the specific width is greater than 0 μm and less than 0.8 μm. The photomask of claim 10, wherein the light-shielding film provided with an anti-reflection layer on the surface of the optical film system, and the film thickness reduction portion is formed by the disappearance of at least a part of the anti-reflection layer. A method for manufacturing a display device includes the following steps: preparing a photomask as in claim 10 or 11; and using an exposure device to transfer the above-mentioned transfer pattern to a transfer object.

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