JP2020154338A - Method of manufacturing photomask, photomask, and method of manufacturing display device - Google Patents

Abstract

To provide a method of manufacturing a photomask which is finer and has both higher CD accuracy and transmittance accuracy.SOLUTION: The method of manufacturing a photomask which is provided with a transfer pattern including a translucent part, a first transmission control part, and a second transmission control part on a transparent substrate includes: a step of preparing a photomask blank in which a first thin film having a predetermined exposure light transmittance is formed on the transparent substrate; a first patterning step of etching the first thin film to form a first thin film pattern; and a second patterning step of forming a second thin film on the transparent substrate on which the first thin film pattern is formed, and etching the second thin film to form a second thin film pattern. In the second patterning step, only the second thin film is etched.SELECTED DRAWING: Figure 1

Description

The present invention relates to a multi-gradation photomask useful for manufacturing a display device represented by a liquid crystal panel or an organic EL panel and a manufacturing method thereof, and a method for manufacturing a display device using the multi-gradation photomask. ..

In recent years, display devices typified by liquid crystal panels and organic EL panels have been required to be further miniaturized, and the photomask patterns for manufacturing these have also tended to be miniaturized. It has become prominent. In particular, the reason why miniaturization of display devices is desired is that there are advantages not only in improving image quality such as increase in pixel density, improvement in display brightness, and improvement in reaction speed, but also in terms of energy saving. Is related to that. In addition, along with such miniaturization trends, quality requirements for photomasks are increasing.

Conventionally, a multi-gradation photomask (gray tone mask) having a transfer pattern in which a light-shielding film and a semi-transmissive film formed on a transparent substrate are patterned is known. This multi-gradation photomask is usefully used in the manufacture of display devices and the like.
For example, Patent Document 1 below describes a halftone film type gray tone mask and a method for manufacturing the same.

Japanese Unexamined Patent Publication No. 2005-257712

This multi-gradation photomask has three or more portions having different light transmittances, such as a light-shielding portion, a translucent portion, and a semi-transmissive portion, in a transfer pattern, thereby forming an on-transfer object. , An attempt is made to form a resist pattern having a plurality of residual film thicknesses. When this resist pattern is used as an etching mask for processing a thin film formed on a transfer body, it functions as an etching mask having a different shape by reducing the film of the resist pattern after the first etching. However, since the second etching can be performed, the multi-gradation photomask can be said to be a photomask having a function corresponding to a plurality of photomasks. Therefore, the number of photomasks required for manufacturing the display device can be reduced, which contributes to the improvement of production efficiency.

Since the multi-gradation photomask has a semi-transmissive portion using a semi-transmissive film that partially transmits the exposure light, in addition to the light-shielding portion and the translucent portion, the light transmittance and transmitted light of this portion are provided. By appropriately controlling the phase characteristics with respect to the light, the partial thickness of the resist pattern formed on the transferred body, the cross-sectional shape thereof, and the like can be changed.

Further, the multi-gradation photomask of Patent Document 1 has a transfer pattern in which a plurality of patterned films (light-shielding film, semi-transmissive film, etc.) are laminated. In such a multi-gradation photomask, the desired transmittance and phase characteristics for the light used at the time of exposure are set, a film material and a film thickness suitable for the desired transmittance and a phase characteristic are selected, and the film formation conditions are adjusted. There is an advantage that a multi-tone photomask having desired optical characteristics can be stably designed.

Here, the method described in Patent Document 1, which is a prior art, will be described.
In the method described in Patent Document 1, the gray tone mask 200 shown in FIG. 3 (i) is manufactured by the process described in FIG. Specifically, first, a photomask blank 100 is prepared in which a light-shielding film 102 is formed on a transparent substrate 101, and a positive resist is applied thereto to form a resist film 103 (see FIG. 3A). ..

Then, it is drawn using a laser drawing machine or the like (first drawing) and developed. As a result, the resist film is removed in the region forming the translucent portion (region A in FIG. 3), and the region forming the light-shielding portion (region B in FIG. 3) and the region forming the translucent portion (C in FIG. 3). A resist pattern 103a in which the resist film remains is formed in the region) (see FIG. 3B).

Next, using the formed resist pattern 103a as a mask, the light-shielding film 102 is etched (first etching), and the light-shielding film pattern 102a is formed in the regions corresponding to the light-shielding portion (B region) and the translucent portion (C region). Form (see FIG. 3 (c)). Then, the resist pattern 103a is removed (see FIG. 3D).
By the first photolithography step described above, the region (A region) corresponding to the translucent portion is defined.

Next, a translucent film 104 is formed on the entire surface of the substrate with the light-shielding film pattern obtained as described above (see FIG. 3E). As a result, a semi-transmissive portion in the A region is formed.
Further, a positive resist is applied to the entire surface of the translucent film 104 to form a resist film 105 (see FIG. 3 (f)), and drawing is performed (second drawing). After development, the resist film 105 is removed from the translucent portion (C region), and a resist pattern 105a in which the resist film remains in the light-shielding portion (B region) and the semi-transmissive portion (A region) is formed (FIG. 3 (FIG. 3). g) See).

Using this as a mask, the semitransparent film 104 in the C region serving as the translucent portion and the light-shielding film pattern 102a are removed by etching (second etching) (see FIG. 3H). Here, by assuming that the etching characteristics of the semi-transmissive film and the light-shielding film are the same or similar, continuous etching is possible. Then, after the second etching, the resist pattern 105a is removed to complete the gray tone mask 200 (see FIG. 3 (i)).

According to the method described above, the light-shielding film and the semi-transmissive film are patterned by two lithography steps (drawing, development, etching), respectively, and a gray tone mask having a light-shielding portion, a translucent portion, and a semi-transmissive portion is obtained. Manufactured.

By the way, in display devices equipped with liquid crystals and organic EL, further technological improvements are required in many aspects such as image brightness, sharpness, reaction speed, reduction of power consumption, and cost reduction. There is. Under such circumstances, not only can a photomask for manufacturing these display devices form a finer pattern more precisely than before, but also the pattern can be transferred to a transfer target (panel substrate, etc.) at low cost. Function is required. In addition, the design of the required transfer pattern is also diversified and complicated.

Under these circumstances, the following new problems have been found through the examination by the present inventors.
According to the step of Patent Document 1 described above, in the second etching, two films, a semitransmissive film and a light-shielding film, are continuously etched and removed in one step (see FIG. 3H). Here, for example, assuming that the light-shielding film is a film containing chromium as a main component and the semi-transmissive film is made of a chromium compound, the etching required time of the light-shielding film of the former is X (for example, 50 seconds), and the latter Assuming that the required etching time of the semitransparent film is Y (for example, 10 seconds), the second etching requires an etching time of X + Y (for example, 60 seconds), and a single film of a light-shielding film or a semitransparent film is etched. It takes a long time compared to the case.

Here, as the etching method, wet etching is applied. This is because wet etching can be applied extremely advantageously to photomasks for manufacturing display devices. This is a relatively large area (for example, 300 mm or more on a side), and for photomasks for manufacturing display devices in which substrates of various sizes exist, wet etching is a facility compared to dry etching, which requires a vacuum device. This is because it is very advantageous both in terms of efficiency and efficiency.

In addition, wet etching has a strong isotropic etching property, and etching (side etching) proceeds not only in the depth direction of the film to be etched but also in the direction parallel to the surface of the film to be etched. In general, when a long etching time is required, the in-plane variation of the etching amount tends to increase. Therefore, as the wet etching time becomes longer, the side etching amount increases and the amount of in-plane etching increases. Variations in the area also increase. Therefore, when the two films, the semitransmissive film and the light-shielding film, are continuously etched and removed in one step by the second etching described above, the line width or dimension (CD: Critical Dimension) of the transfer pattern to be formed is formed. , The following is used to mean the line width or dimension of the pattern.) Accuracy tends to deteriorate. That is, the second etching that requires X + Y (seconds) has a problem in this respect. In addition, the amount of the etching agent used increases with the length of the etching time, and the burden of waste liquid treatment containing heavy metals also increases.

Further, the present inventors have paid attention to the possibility that the following problems may occur when the design of the transfer pattern is complicated or when there is a fine size (CD) pattern.

In FIG. 3 (i) showing the method of Patent Document 1, a pattern including a portion in which the semitransmissive portion and the light-shielding portion are adjacent to each other is formed. In addition to such a pattern, a pattern for manufacturing a recent display device is formed. The transfer patterns of photomasks include more complex ones. For example, there is a need for a transfer pattern having a portion in which a translucent portion and a semitransparent portion are adjacent to each other in addition to the adjacent portion.

Therefore, for example, consider the case where the transfer pattern shown in FIG. 3 has a portion in which the translucent portion and the semitransparent portion are adjacent to each other (see FIG. 4 (i)). The steps (second photolithography step) of FIGS. 4 (f) to 4 (i) correspond to FIGS. 3 (f) to 3 (i), respectively.
Here, in the step of FIG. 4 (h) showing the second etching, the portion (N) in which the semi-transmissive film 104 and the light-shielding film pattern 102a are continuously etched and removed as in the step of FIG. 3 (h) described above. ) Exists. For this reason, the etching time becomes long due to the large etching depth, and the side etching amount also increases according to the etching depth, so that the formed pattern size (CD) tends to be out of order. In addition, the distribution of CD errors in the plane tends to be large (see FIG. 4 (h')).

Further, in the step of FIG. 4H, a portion (N) in which the semi-transmissive film 104 and the light-shielding film pattern 102a are continuously etched and removed, and a portion (K) in which only the semi-transmissive film 104 is etched and removed. ) And occur. At this time, it becomes difficult to set the required time for the second etching. This is because when the latter K portion requires an etching time of T (seconds), the former N portion requires an etching time corresponding to T + α (seconds).

Therefore, in the step of FIG. 4H, when the etching of the N portion is actually completed, the etching proceeds excessively in the K portion, and side etching is performed on the semitransparent film 104 under the resist pattern 105a. (See FIG. 4 (h')). As a result, the size of the formed semitransparent film pattern 104a becomes smaller by W (μm) in the K portion with respect to the size of the resist pattern 105a, and the pattern size (CD) becomes inconsistent. The distribution of CD errors in the above tends to be large (see FIG. 4 (i')).

Further, in the semitransparent film used for such a multi-gradation photomask, control of the light transmittance is extremely important. However, in the method of the prior art of FIG. 3, when the semitransparent film is formed. Since a pattern made of a light-shielding film already exists on the transparent substrate, it is not easy to measure the light transmittance of the semitransparent film formed. In particular, since a photomask for manufacturing a display device has a large area (for example, a quadrangle having a side of 300 mm or more), a large device (such as a sputtering device) is used for film formation, but the film-forming material is uniformly deposited in the plane. There are also difficulties. For example, the film thickness may be distributed in the plane depending on the position relative to the sputtering target. If this film thickness is measured accurately and this tendency is correctly grasped, the influence can be offset by the second etching (patterning of the light-shielding film) in the manufacturing method of the present invention described later, but FIG. In the method of the prior art described in the above, there is a problem that it is difficult to accurately measure the transmittance of the semitransparent film at each position in the plane.

Therefore, it has been found that the method of the prior art shown in FIG. 3 still has a problem when trying to manufacture a multi-gradation photomask having finer and higher CD accuracy and transmittance accuracy.
Therefore, the present invention relates to a photomask manufacturing method capable of manufacturing a multi-gradation photomask having finer, higher CD accuracy and transmittance accuracy, a photomask, and a display device using the photomask. It is an object of the present invention to provide the manufacturing method of.

As a result of diligent studies to solve the above problems, the present inventor has found that the above problems can be solved by an invention having the following configuration, and has completed the present invention.
That is, the present invention has the following configuration.

(Structure 1)
A method for manufacturing a photomask having a transfer pattern including a light transmitting unit, a first transmission control unit, and a second transmission control unit on a transparent substrate, wherein a predetermined exposure light transmittance is provided on the transparent substrate. A step of preparing a photomask blank having a first thin film formed therein, a first patterning step of forming a first thin film pattern by etching the first thin film, and a step of forming the first thin film pattern. The second patterning step includes a second patterning step of forming a second thin film on the transparent substrate and etching the second thin film to form a second thin film pattern. In the second patterning step, the second thin film is formed. A method for manufacturing a photomask, which comprises etching only a thin film.

(Structure 2)
The transparent substrate surface of the transparent substrate is exposed, and the first transmission control portion has a portion on which only the first thin film is formed on the transparent substrate, and the second transmission control portion Is a method for manufacturing a photomask according to the first embodiment, wherein the transparent substrate has a portion on which only the second thin film is formed.
(Structure 3)
The method for producing a photomask according to the configuration 1 or 2, wherein the first thin film is made of a material having resistance to the etching agent of the second thin film.

(Structure 4)
The method for producing a photomask according to the configuration 1 or 2, wherein the first thin film is made of a material that is etched by the etching agent of the second thin film.
(Structure 5)
The configuration 4 comprises a step of forming an etching stopper film on the transparent substrate on which the first thin film pattern is formed after the first patterning step and before forming the second thin film. The method for manufacturing a photomask described.

(Structure 6)
The photomask according to configuration 5, further comprising a step of removing the light-transmitting portion or the etching stopper film of the light-transmitting portion and the first transmission control unit after the second patterning step. Production method.
(Structure 7)
The method for producing a photomask according to any one of configurations 1 to 6, wherein the first thin film is a translucent film that partially transmits exposure light.

(Structure 8)
The exposure light transmitted through the first transmission control unit is characterized in that the phase difference φ (degree) satisfies φ ≦ 90 with respect to the representative wavelength of the exposure light transmitted through the light transmission unit. The method for producing a photomask according to any one of 6.
(Structure 9)
The exposure light transmitted through the first transmission control unit has a phase difference φ (degree) of φ ≦ 90 with respect to the representative wavelength of the exposure light transmitted through the light transmission unit, and the first transmission control The method for manufacturing a photomask according to any one of configurations 1 to 6, wherein the light transmittance Tf (%) of the portion satisfies 5 ≦ Tf ≦ 60.

(Structure 10)
The exposure light transmitted through the first transmission control unit is characterized in that the phase difference φ (degree) satisfies 150 ≦ φ ≦ 210 with respect to the representative wavelength of the exposure light transmitted through the light transmission unit. The method for producing a photomask according to any one of 1 to 6.
(Structure 11)
The exposure light transmitted through the first transmission control unit has a phase difference φ (degree) of 150 ≦ φ ≦ 210 with respect to the representative wavelength of the exposure light transmitted through the light transmission unit, and has a light transmittance. The method for producing a photomask according to any one of configurations 1 to 6, wherein Tf (%) satisfies 5 ≦ Tf ≦ 60.

(Structure 12)
The method for producing a photomask according to any one of configurations 1 to 11, wherein the second thin film is a translucent film that partially transmits exposure light.
(Structure 13)
The exposure light transmitted through the second transmission control unit is characterized in that the phase difference φ (degree) satisfies 0 <φ ≦ 90 with respect to the representative wavelength of the exposure light transmitted through the light transmission unit. The method for producing a photomask according to any one of 1 to 11.

(Structure 14)
The exposure light transmitted through the second transmission control unit has a phase difference φ (degree) of 0 <φ ≦ 90 and a light transmittance with respect to the representative wavelength of the exposure light transmitted through the light transmission unit. The method for producing a photomask according to any one of configurations 1 to 11, wherein Tf (%) satisfies 5 ≦ Tf ≦ 80.
(Structure 15)
The exposure light transmitted through the second transmission control unit has a phase difference φ (degree) of 150 <φ≤210 and a light transmittance with respect to the representative wavelength of the exposure light transmitted through the light transmission unit. The method for producing a photomask according to any one of configurations 1 to 11, wherein Tf (%) satisfies 5 ≦ Tf ≦ 60.

(Structure 16)
The method for producing a photomask according to any one of configurations 1 to 11, wherein the second thin film is a light-shielding film.
(Structure 17)
The method for manufacturing a photomask according to the configuration 16, wherein a reflection reducing layer for reducing light reflection is provided on the surface portion of the second thin film.

(Structure 18)
The method for producing a photomask according to any one of configurations 1 to 17, wherein the photomask blank has an additional constituent film and a resist film on the first thin film.
(Structure 19)
The method for producing a photomask according to the configuration 18, wherein the adhesion between the additional constituent film and the resist film is higher than the adhesion between the first thin film and the resist film.

(Structure 20)
Prior to the first patterning step, there is a preliminary patterning step of etching the additional constituent film to form an additional constituent film pattern, and in the first patterning step, the additional constituent film pattern is used as a mask and the first The method for producing a photomask according to the configuration 18 or 19, which comprises etching a thin film.
(Structure 21)
The method for producing a photomask according to the configuration 20, wherein the additional constituent film pattern is removed after the first patterning step and before the second patterning step.

(Structure 22)
On the transparent substrate, a transfer pattern including a light transmitting unit, a first transmission control unit, and a second transmission control unit, and including an adjacent portion adjacent to the first transmission control unit and the second transmission control unit is provided. A method for manufacturing a photomask, which is a step of preparing a photomask blank having a first thin film having a predetermined exposure light transmittance formed on the transparent substrate, and a first in a region to be the first transmission control unit. A first patterning step of forming a first thin film pattern by forming a resist pattern and etching the first thin film, and a second thin film are formed on the transparent substrate on which the first thin film pattern is formed. The film forming step of forming and the second patterning step of forming the second resist pattern in the region to be the second transmission control unit and etching the second thin film to form the second thin film pattern. In the second patterning step, a laminated portion is formed in which the second resist pattern is laminated with the first thin film pattern in the adjacent portion, and the second thin film is used by using the second resist pattern. A method for manufacturing a photomask, which comprises etching only a photomask.

(Structure 23)
The transparent substrate surface of the transparent substrate is exposed, the first transmission control unit includes a portion in which only the first thin film is formed on the transparent substrate, and the second transmission control unit includes a portion in which only the first thin film is formed. The method for manufacturing a photomask according to the configuration 22, wherein a portion on which only the second thin film is formed is included on the transparent substrate.
(Structure 24)
The method for producing a photomask according to the configuration 22 or 23, wherein the width M1 of the laminated portion is in the range of 0.5 to 2 μm.

(Structure 25)
A photomask having a transfer pattern including a light-transmitting unit, a first transmission control unit, and a second transmission control unit on a transparent substrate, and the transfer pattern has a predetermined exposure light transmittance. The transparent substrate surface is exposed in the translucent portion including one thin film and the second thin film, and the first transmissive control unit does not form the second thin film on the transparent substrate. The first thin film is formed, and in the second transmission control unit, at least the second thin film is formed on the transparent substrate, and the boundary between the first transmission control unit and the second transmission control unit is set. , A photomask characterized in that the cross section to be etched of the first thin film is not formed, but the cross section to be etched of the second thin film is formed.

(Structure 26)
The transparent substrate surface of the transparent substrate is exposed, and the first transmission control portion has a portion on which only the first thin film is formed on the transparent substrate, and the second transmission control portion 25 is the photomask according to the configuration 25, wherein the transparent substrate has a portion on which only the second thin film is formed.
(Structure 27)
The photomask according to the configuration 25 or 26, wherein the first thin film is made of a material that is resistant to the etching agent of the second thin film.

(Structure 28)
The first thin film is made of a material that is etched by the etching agent of the second thin film, and the second transmission control unit is a portion in which an etching stopper film and the second thin film are laminated in this order. The photomask according to configuration 25, wherein the photomask has.
(Structure 29)
The configuration according to any one of configurations 25 to 28, wherein the edge portion of the second transmission control unit adjacent to the first transmission control unit has a laminated portion of the first thin film and the second thin film. Photomask.

(Structure 30)
The photomask according to the configuration 29, wherein the width M2 of the laminated portion is in the range of 0.5 to 2 μm.
(Structure 31)
The photomask according to any one of configurations 25 to 30, wherein the first thin film is a translucent film and the second thin film is a light-shielding film.

(Structure 32)
A photomask having a transfer pattern including a light-transmitting unit, a first transmission control unit, and a second transmission control unit on a transparent substrate, and the transfer pattern has a predetermined exposure light transmittance. A first thin film pattern composed of one thin film and a second thin film pattern composed of a second thin film are included, the transparent substrate surface is exposed in the translucent portion, and the first transmission control unit is on the transparent substrate. The second transmission control unit has a portion on the transparent substrate in which only the first thin film pattern is formed, and the first transmission control unit has a portion in which only the second thin film pattern is formed. A photomask characterized by having a laminated portion in which the first thin film pattern and the second thin film pattern are laminated, which is sandwiched between the control unit and the second transmission control unit.

(Structure 33)
The photomask according to the configuration 32, wherein the width M2 of the laminated portion is in the range of 0.5 to 2 μm.
(Structure 34)
The photomask according to configuration 32 or 33, wherein the edge of the first thin film pattern and the second thin film pattern has a wet-etched cross section of the first thin film and the second thin film, respectively.

(Structure 35)
The photomask according to any one of configurations 32 to 34, wherein the first thin film is a translucent film that partially transmits exposure light.
(Structure 36)
The exposure light transmitted through the first transmission control unit is characterized in that the phase difference φ (degree) satisfies φ ≦ 90 with respect to the representative wavelength of the exposure light transmitted through the light transmission unit. The photomask according to any of 34.

(Structure 37)
The exposure light transmitted through the first transmission control unit has a phase difference φ (degree) of φ ≦ 90 with respect to the representative wavelength of the exposure light transmitted through the light transmission unit, and has a light transmittance Tf ( %) Is the photomask according to any one of configurations 32 to 34, wherein 5 ≦ Tf ≦ 60 is satisfied.
(Structure 38)
The exposure light transmitted through the first transmission control unit is characterized in that the phase difference φ (degree) satisfies 150 ≦ φ ≦ 210 with respect to the representative wavelength of the exposure light transmitted through the light transmission unit. The photomask according to any one of 32 to 34.

(Structure 39)
The exposure light transmitted through the first transmission control unit has a phase difference φ (degree) of 150 ≦ φ ≦ 210 with respect to the representative wavelength of the exposure light transmitted through the light transmission unit, and has a light transmittance. The photomask according to any one of configurations 32 to 34, wherein Tf (%) satisfies 5 ≦ Tf ≦ 60.
(Structure 40)
The photomask according to any one of configurations 32 to 39, wherein the second thin film is a light-shielding film.

(Structure 41)
The photomask according to any one of configurations 32 to 39, wherein the second thin film is a translucent film that partially transmits exposure light.
(Structure 42)
The exposure light transmitted through the second transmission control unit is characterized in that the phase difference φ (degree) satisfies 0 <φ ≦ 90 with respect to the representative wavelength of the exposure light transmitted through the light transmission unit. The photomask according to any one of 32 to 39.

(Structure 43)
The exposure light transmitted through the second transmission control unit has a phase difference φ (degree) of 0 <φ ≦ 90 and a light transmittance with respect to the representative wavelength of the exposure light transmitted through the light transmission unit. The photomask according to any one of configurations 32 to 39, wherein Tf (%) satisfies 5 ≦ Tf ≦ 80.
(Structure 44)
The exposure light transmitted through the second transmission control unit has a phase difference φ (degree) of 150 <φ≤210 and a light transmittance with respect to the representative wavelength of the exposure light transmitted through the light transmission unit. The photomask according to any one of configurations 32 to 39, wherein Tf (%) satisfies 5 ≦ Tf ≦ 60.

(Structure 45)
The photomask according to any one of configurations 25 to 44, wherein the transfer pattern is a pattern for manufacturing a display device.
(Structure 46)
The photomask obtained by the method for producing a photomask according to any one of configurations 1 to 24 or the photomask according to any one of configurations 25 to 44 is prepared, and the transfer pattern is obtained using an exposure apparatus. A method for manufacturing a display device, which comprises a step of transferring to a transfer target.

According to the present invention, in each etching step of the first thin film and the second thin film, only each film is etched, so that the etching time can be set as compared with the case where a plurality of laminated films are continuously etched. Since it is short, it is possible to reduce fluctuations in the pattern size (CD) due to side etching. In particular, if a single film is etched in each of the etching steps, the etching time required can be calculated in advance based on the film quality and film thickness, so that dimensional variation due to side etching can be minimized. it can. Further, if the configuration of the photomask of the present invention is adopted, the design and management of the optical characteristics (for example, transmittance) of the first transmission control unit and the second transmission control unit are simpler and more accurate, and thus are high. The manufacture of high-spec display devices that realize fine and energy-saving is of great significance.
That is, according to the present invention, it is possible to provide a photomask manufacturing method capable of manufacturing a photomask having finer and higher CD accuracy and optical physical property (transmittance, etc.) accuracy, and a photomask. it can.
Further, according to the present invention, by manufacturing a display device using the photomask, it is possible to manufacture a high-spec display device that realizes high definition and energy saving.

It is a figure which shows the process of 1st Embodiment of the manufacturing method of the photomask which concerns on this invention. It is a figure which shows the process of the 2nd Embodiment of the manufacturing method of the photomask which concerns on this invention. It is a figure which shows the manufacturing process of the conventional photomask disclosed in the prior art. It is a reference figure which shows the manufacturing process of the conventional photomask for explaining the problem of the prior art.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.
[First Embodiment]
In the method for producing a photomask according to the present invention, as described in the above configuration 1, a photomask having a transfer pattern including a light transmitting unit, a first transmission control unit, and a second transmission control unit on a transparent substrate is provided. The first thin film pattern is obtained by preparing a photomask blank in which a first thin film having a predetermined exposure light transmittance is formed on the transparent substrate, and by etching the first thin film. The second thin film pattern is formed by forming the second thin film on the transparent substrate on which the first thin film pattern is formed and etching the second thin film. The second patterning step includes a second patterning step, and the second patterning step is characterized in that only the second thin film is etched.
In the first embodiment described below, the first transmission control unit is a semi-transmissive unit that partially transmits exposure light, and the second transmission control unit is a light-shielding unit. Then, the first thin film is used as a translucent film, and the second thin film is used as a light-shielding film.

FIG. 1 is a diagram showing a process of the first embodiment of the method for manufacturing a photomask according to the present invention.
Hereinafter, each step will be described in order.
First, a photomask blank (a substrate with a semitransparent film) 10 having a semitransparent film 2 having a predetermined exposure light transmittance formed on the transparent substrate 1 is prepared (see FIG. 1A).

Here, as the transparent substrate 1, a transparent material made of quartz glass or the like is polished flat and smooth. The transparent substrate used for the photomask for manufacturing a display device preferably has a main surface of a quadrangle having a side of 300 mm or more and a thickness of 5 to 13 mm.
A semi-transmissive film 2 is formed on one main surface of the transparent substrate 1 by a known film forming means such as a sputtering method. The material and film thickness of the translucent film 2 can be determined in advance so as to have a desired transmittance with respect to the exposure light used when exposing the photomask.

As the exposure light, for example, a light source including i-line, h-line, and g-line, which is included in an exposure apparatus for liquid crystal, can be used. Therefore, the standard of transmittance can be set for light in these wavelength ranges, and can be generally expressed as a numerical value for a representative wavelength (here, i-line) included in these wavelengths.

The light transmittance Tf of the semitransparent film 2 is preferably 5 to 60% (the transparent substrate is 100%) with respect to the i-line. Further, it is preferably 10 to 40%.

Here, Tf is the light transmittance of the semitransparent film 2 used as described above. When a fine pattern is formed on the semi-transmissive film 2, the effective light transmittance of the semi-transmissive portion is affected by the diffraction and interference of light by the light-shielding portion and the translucent portion arranged around it. Although it may be different from that at the time of film formation, here, it refers to the transmittance peculiar to the film, which is not affected by light diffraction and interference due to the surrounding pattern. If the semi-transmissive film 2 has a laminated structure, it has a unique transmittance as the laminated structure.

Further, the semitransparent film 2 can have a desired phase shift action with respect to the representative wavelength of the exposure light. Considering that a resist pattern having a plurality of residual film thicknesses is formed on the transfer target as a multi-gradation photomask, the phase shift amount (φ) of the semitransparent film 2 is 0 <φ ≦ 90. The degree is preferably 5 ≦ φ ≦ 60 degrees. This is to prevent the generation of unnecessary protrusions (in the case of positive resist) of the resist pattern at the positions corresponding to the semitransparent portion and the translucent portion of the multi-gradation photomask.
Of course, in order to control the shape of the resist pattern formed on the transferred body by the phase shift action, it may be about 150 ≦ φ ≦ 210 degrees, or 60 ≦ φ ≦ 120 degrees.

The material of the translucent film 2 can be, for example, a film containing Si, Cr, Ta, Zr, etc., and an appropriate one can be selected from these oxides, nitrides, carbides, and the like. .. As the Si-containing film, a Si compound (SiON or the like), a transition metal silicide (MoSi or the like), or a compound thereof can be used. Examples of the MoSi compound include MoSi oxides, nitrides, oxide nitrides, and carbides of oxide.

When the material of the semitransparent film 2 is a Cr-containing film, Cr compounds (oxides, nitrides, carbides, nitrides oxides, carbides, carbides oxides) can be used.

In the present embodiment, it is desirable that the semi-transmissive film 2 has etching selectivity (different etching characteristics) from each other with the light-shielding film 5 described later. That is, it is preferable that the semi-transmissive film 2 is resistant to the etching agent of the light-shielding film 5 (specifically, it is an etching solution because wet etching is applied in this embodiment). Here, resistance means that the etching rate ratio of the semitransparent film 2 to the etching solution of the light-shielding film 5 with respect to the light-shielding film 5 is 1/50 or less, preferably 1/100 or less. Is desired. From this point of view, for example, if a film containing Cr is used for the light-shielding film 5, a Si-based film (for example, one containing MoSi) can be applied to the translucent film 2. Alternatively, the reverse can be done.

A known method or apparatus such as a sputtering method can be applied to the film formation of the semitransparent film 2. The film thickness of the semi-transmissive film 2 is a film thickness determined in advance so as to have a desired transmittance with respect to the exposure light used when exposing the photomask.

After the semitransmissive film 2 is formed, it is preferable to set an appropriate number of measurement points in the plane and measure the light transmittance (absolute value and its in-plane distribution). For example, a spectrophotometer can be used for the measurement. Since some film thickness distribution tendency may occur in the semitransparent film 2 after film formation depending on the position of the main surface of the substrate due to the film forming apparatus and the film forming conditions, the data obtained by the measurement is stored. However, it can be used for the purpose of product warranty or for reflection in drawing data in the subsequent process. As described above, the transmittance management of the semi-transmissive film is simpler and more accurate, so that the transmittance accuracy can be improved.

Next, a resist film 3 is applied and formed on the surface of the prepared photomask blanks 10 to obtain a blank with a resist. A predetermined pattern is drawn 4 (first drawing) (see FIG. 1B). If necessary, the surface of the semi-transmissive film 2 can be subjected to a surface treatment for improving the adhesion with the resist film 3.
Further, in order to supplement the adhesion between the semitransparent film 2 and the resist film, a constituent film may be additionally arranged between them.
The material of the constituent film can be selected so that the adhesion between the constituent film and the resist film is higher than the adhesion between the semitransparent film and the resist film. That is, by arranging the constituent film, the adhesion between the resist film and the translucent film that come into direct contact with the constituent film can be improved. The material of the additional constituent film shall have a higher adhesion to the resist film than the adhesion between the semitransmissive film and the resist film. For example, it can be a Cr compound.

For the coating formation of the resist film 3, known materials such as a slit coater and a spin coater can be used. Either a positive type or a negative type resist can be used as appropriate, but here, an example using a positive type will be described.

The first patterning step is carried out. First, the resist film 3 formed by coating is drawn 4 with drawing data based on a desired pattern using a drawing device. As the drawing device, an electron beam or a laser-applied drawing device can be used, but laser drawing can be usefully used as a photomask for manufacturing a display device.

Next, the drawn resist film 3 is developed to form a resist pattern 3a (first resist pattern) (see FIG. 1C).

Next, the semitransparent film 2a is formed by wet etching (first etching) using the formed resist pattern 3a as an etching mask (see FIG. 1D). Here, since the etching target is only the semitransmissive film 2, the etching end point can be accurately set by referring to the etching rate grasped in advance.

Then, the remaining resist pattern 3a is peeled off and removed (see FIG. 1 (e)).
Here, the pattern dimension (CD) of the semitransparent film pattern 2a is measured as needed. Since the pattern edge is only a translucent film, measurement can be performed relatively easily.

When an additional constituent film is formed between the translucent film 2 and the resist film 3, the constituent film is wet-etched (pre-etched) using the resist pattern 3 as an etching mask to form the additional film. The semi-transmissive film pattern 2a can be formed by wet-etching (first etching) the semi-transmissive film 2 using the constituent film pattern of 1 as an etching mask.
In this case, it is preferable to remove the additional constituent film pattern before the second patterning step below.

Next, a light-shielding film 5 is formed on the entire surface of the transparent substrate 1 on which the semi-transmissive film pattern 2a is formed on the main surface (see FIG. 1 (f)). Here, as in the case of forming the semitransparent film 2, the existing film forming apparatus can be applied.

The material of the light-shielding film 5 can be selected from the same materials as those mentioned as the material of the semi-transmissive film 2. Alternatively, the above-mentioned metal such as Cr and Si may be used alone. Further, a reflection reduction layer for reducing (suppressing) light reflection may be provided on the surface portion of the light-shielding film.

As described above, in the present embodiment, the light-shielding film 5 is selected to have different etching characteristics from the material used for the semi-transmissive film 2. For example, the light-shielding film 5 has an etching rate ratio of 1/50 or less, preferably 1/100 or less, with respect to the etching solution of the semi-transmissive film 2. desirable. Therefore, for example, a Si-containing material can be used for the semi-transmissive film 2, a Cr-containing material can be used for the light-shielding film 5, and vice versa.

Further, the film thickness of the light-shielding film 5 is set in consideration of the fact that the light-shielding property can be sufficiently exhibited and that the etching described later does not require an excessive time. Specifically, the optical density OD can be 3 or more, preferably 4 or more, for example, 4 ≦ OD ≦ 6.

Next, a resist film 6 (also a positive type) is applied and formed on the light-shielding film 5, and a predetermined pattern is drawn 7 (second drawing) (see FIG. 1 (g)). The drawing method is the same as in the case of the first drawing described above.
However, if there is an unacceptable variation in the in-plane transmittance distribution data obtained by measuring after the film formation of the semi-transmissive film 2, and this is to be corrected by the pattern of the light-shielding film 5. , The drawing data for the second drawing can be processed. This is because, for example, in a fine semi-transmissive portion adjacent to a light-shielding portion, the transmission intensity of the exposure light transmitted through the semi-transmissive portion tends to decrease.
Using this principle, for example, for a semi-transmissive part in a region where the transmittance is lower than the design value, the dimension is made larger than the design value to correct in the direction of increasing the transmission intensity of the exposure light. Can be done.

Next, the drawn resist film 6 is developed to form a resist pattern 6a (second resist pattern) (see FIG. 1 (h)).

Next, the light-shielding film pattern 5a is formed by wet-etching (second etching) the light-shielding film 5 using the formed resist pattern 6a as an etching mask (see FIG. 1 (i)). Since the etching target here is only the light-shielding film 5, there is no difficulty in setting the etching end point by referring to the etching rate grasped in advance. Further, as described above, in the present embodiment, the semi-transmissive film 2 is made of a material that is resistant to the etching agent of the light-shielding film 5. Therefore, in the second etching, the semi-transmissive portion forming region is formed. On the top, only the light-shielding film 5 is removed by etching, and the semitransparent film pattern 2a in the lower layer is not affected by etching.

Then, the remaining resist pattern 6a is peeled off to complete a photomask 20 (multi-gradation photomask) including a transfer pattern including a light-transmitting portion, a light-shielding portion, and a semi-transmissive portion (FIG. 1 (FIG. 1). j) See).

The photomask 20 (multi-gradation photomask) illustrated here has the following configuration. That is, the surface of the transparent substrate was exposed in the translucent portion, and only the semitransparent film (the first thin film) was formed on the transparent substrate in the semitransparent portion (first transmission control unit). The light-shielding portion (second transmission control unit) has a portion in which only the light-shielding film (the second thin film) is formed on the transparent substrate.

Further, the photomask 20 has a portion adjacent to a light-shielding portion and a semi-transmissive portion. In the light-shielding portion, a laminated portion of a semi-transmissive film (semi-transmissive film pattern 2a) and a light-shielding film (light-shielding film pattern 5a) is provided in the vicinity of the edge in contact with the semi-transmissive portion with a predetermined constant width. This is done in consideration of the possibility that the light-shielding portion and the semi-transmissive portion are not adjacent to each other and are separated from each other when the alignment deviation occurs in the above two drawings (first drawing and second drawing). It is an alignment margin for absorbing the deviation, and can be formed by processing the drawing data of the first drawing or the second drawing. For example, in the vicinity of the boundary between the light-shielding portion and the semi-transmissive portion, the edge portion of the second resist pattern partially overlaps (overlaps) with the already formed edge portion of the semi-transmissive film pattern. The dimensions of the second resist pattern can be set. At this time, the width of the laminated portion (referred to as M1) is not particularly limited in the processing of the drawing data, but is, for example, 0.5 μm or more, preferably 0.5 to 2 μm, and more preferably 0. It can be 5 to 1 μm.
That is, in the photomask by the above-mentioned manufacturing method, only the semi-transmissive film is formed on the transparent substrate in the semi-transmissive portion, and only the light-shielding film is formed on the transparent substrate in the light-shielding portion except for the laminated portion as the alignment margin. It is formed.

The present invention also provides a photomask.
The photomask 20 obtained by the present embodiment has the following features.
That is, it is a photomask provided with a transfer pattern including a light-transmitting portion, a light-shielding portion, and a semi-transmissive portion on a transparent substrate, and the transparent substrate surface is exposed in the transparent portion. In the semi-transmissive portion, the light-shielding film is not formed on the transparent substrate, the semi-transmissive film is formed, and in the light-shielding portion, at least the light-shielding film is formed on the transparent substrate. The boundary between the semi-transmissive portion and the light-shielding portion is a photomask characterized in that the cross-section to be etched of the semi-transmissive film is not formed, but the cross-section to be etched of the light-shielding film is formed. is there.
That is, as is clear from FIG. 1 (j), the edges of the semi-transmissive film pattern and the light-shielding film pattern have wet-etched cross sections of the semi-transmissive film and the light-shielding film, respectively, but the semi-transmissive film pattern The edge position does not match the edge position of the light-shielding film pattern. The cross section to be etched here is a cross section obtained by wet etching in the present embodiment.
The fact that the positions of the cross sections to be etched of the semi-transmissive film and the light-shielding film do not match in this way is related to the above-mentioned alignment margin.

The materials for the semi-transmissive film and the light-shielding film in the photomask are as described above, and in the photomask of the present embodiment, the semi-transmissive film is an etching agent for the light-shielding film. It is made of a material that is resistant to resistance.
Further, the edge portion adjacent to the semi-transmissive portion of the light-shielding portion has a laminated portion of the semi-transmissive film and the light-shielding film, and the width M of the laminated portion (see FIG. 1 (j)) is, for example, 0. The range is preferably 5 to 2 μm.
Further, in the photomask of the present embodiment, the transfer pattern is, for example, a pattern for manufacturing a display device, and is particularly useful for manufacturing a display device.

As described above, according to the present embodiment, in each etching step of the semitransmissive film and the light-shielding film, only each film is etched, as compared with the case where a plurality of laminated films are continuously etched. Since the etching time is set short, the pattern dimension (CD) fluctuation due to side etching can be reduced. In particular, if a single film is etched in each of the etching steps, the etching time required can be calculated in advance based on the film quality and film thickness, so that dimensional variation due to side etching can be minimized. it can. Further, if the photomask configuration of the present embodiment is adopted, the transmittance management of the semitransmissive film is simpler and more accurate, so that it is possible to manufacture a high-spec display device that realizes high definition and energy saving. , Has great significance.
That is, according to the present embodiment, it is possible to provide a photomask manufacturing method capable of manufacturing a multi-gradation photomask having both finer and higher CD accuracy and transmittance accuracy, and a photomask. ..

In the above embodiment, the first transmission control unit is a semi-transmissive unit that partially transmits exposure light, the second transmission control unit is a light-shielding unit, and the first thin film is a semi-transmissive film or a second thin film. Although the light-shielding film has been described as an example, the production method of the present invention can obtain excellent effects even when other thin films are applied. For example, the first thin film and the second thin film may be semi-transmissive films having predetermined exposure light transmittances, respectively. In this case, the first thin film and the second thin film can be films containing Si, Cr, Ta, Zr, etc., which are exemplified as the above-mentioned semitransparent film materials, respectively, and oxides and nitrides thereof. , Carbides, etc. can be selected as appropriate.
When the first thin film and the second thin film are semi-transmissive films each having a predetermined exposure light transmittance, and if they are to have resistance to each other's etching agents, for example, one is Cr-based and the other is Cr. Can be Si-based or transition metal VDD-based.

Further, in the photomask of the present invention, as a method of applying these first thin films and second thin films, for example, more specifically,
a. The exposure light transmitted through the first transmission control unit having a portion where only the first thin film is formed on the transparent substrate is relative to a representative wavelength of the exposure light transmitted through the transparent portion where the surface of the transparent substrate is exposed. , When the phase difference φ (degree) satisfies φ ≦ 90,
b. The exposure light transmitted through the first transmission control unit has a phase difference φ (degree) of φ ≦ 90 with respect to the representative wavelength of the exposure light transmitted through the light transmission unit, and has a light transmittance Tf ( %) Satisfies 5 ≦ Tf ≦ 60
c. When the phase difference φ (degree) of the exposure light transmitted through the first transmission control unit satisfies 150 ≦ φ ≦ 210 with respect to the representative wavelength of the exposure light transmitted through the light transmission unit,
d. The exposure light transmitted through the first transmission control unit has a phase difference φ (degree) of 150 ≦ φ ≦ 210 with respect to the representative wavelength of the exposure light transmitted through the light transmission unit, and has a light transmittance. When Tf (%) satisfies 5 ≦ Tf ≦ 60
e. The exposure light transmitted through the second transmission control unit having a portion where only the second thin film is formed on the transparent substrate has a phase difference φ (degrees) with respect to the representative wavelength of the exposure light transmitted through the transmissive unit. ) Satisfies 0 <φ ≦ 90
f. The exposure light transmitted through the second transmission control unit has a phase difference φ (degree) of 0 <φ≤90 and a light transmittance with respect to the representative wavelength of the exposure light transmitted through the light transmission unit. When Tf (%) satisfies 5 ≦ Tf ≦ 80
g. The exposure light transmitted through the second transmission control unit has a phase difference φ (degree) of 150 <φ≤210 and a light transmittance with respect to the representative wavelength of the exposure light transmitted through the light transmission unit. When Tf (%) satisfies 5 ≦ Tf ≦ 60
Etc. are useful examples. In either case, the CD accuracy is high and controllable, the effect of the present invention can be obtained, and the optical characteristics of the first transmission control unit and the second transmission control unit can be independently designed. , High quality photomasks with desired design values can be produced.

For example, as an example of the photomask described in the first embodiment, the above-mentioned a. Or b. When a light-shielding film is applied to the second thin film, a multi-gradation photomask can be obtained as the photomask of the present invention. As described above, such a multi-gradation photomask functions as a plurality of photomasks to improve the manufacturing efficiency of the display device, or to form a three-dimensional structure having a step by transferring. It has the advantage of being used as a photomask for manufacturing.
Further, on the first thin film, the above c. Or d. When is applied, the photomask of the present invention can be configured as a phase shift mask. In this case, a light-shielding film may be applied to the second thin film, or the above e. Or f. The translucent film described in the above may be applied. The phase shift mask has a function of improving contrast and DOF (Depth of Focus) by utilizing the interference of light generated at the boundary between a semitransparent portion in which the phase of transmitted light is inverted and a translucent portion in which the phase of transmitted light is not inverted.
In particular, on the first thin film, the above c. Or d. Is applied to the second thin film, and the above e. Or f. When is applied, a photomask having the functions of a multi-gradation photomask and a phase shift mask can be configured.

When both the first transmission control unit and the second transmission control unit are semi-transmissive units, and a laminated portion in which the first thin film and the second thin film are laminated is formed near the boundary, the width thereof is wide. Because it is small enough, it does not substantially interfere with the optical action of the photomask. In this case, the width of the laminated portion can be more preferably 1 μm or less, further 0.75 μm or less. More preferably, it is 0.25 to 0.75 μm.
Further, the width M1 of the laminated portion on the drawing data can be set to the same range.
On the other hand, the dimensions of the first transmittance control unit and the second transmittance control unit (or the light-shielding unit) preferably exceed 2 μm, preferably more than 3 μm, even in the smallest portion.

[Second Embodiment]
FIG. 2 is a diagram showing a process of a second embodiment of the photomask manufacturing method according to the present invention.
Hereinafter, each step will be described in order.
First, a photomask blanks 10 having a semitransparent film 2 having a predetermined exposure light transmittance formed on the transparent substrate 1 are prepared (see FIG. 2A).

The photomask blanks 10 are the same as the photomask blanks prepared in the first embodiment described above. Therefore, the range of the light transmittance Tf of the semitransparent film 2 can be the same as that of the first embodiment. Further, the material of the semitransparent film 2 may be appropriately selected from those exemplified in the first embodiment.
However, in the present embodiment, since the etching stopper film is provided between the semi-transmissive film and the light-shielding film as described later, the etching characteristics differ between the semi-transmissive film 2 and the light-shielding film 5 described later. It doesn't have to be. Therefore, for example, there is no problem in using a Cr-based material for the semi-transmissive film 2 and using the light-shielding film 5 as a Cr-based material.

Further, after the film formation of the semi-transmissive film 2, it is preferable to set an appropriate number of measurement points in the plane and measure the light transmittance as in the first embodiment. Since it is formed on the substrate in a single film state, it can be measured easily and accurately.

Next, a resist film 3 is applied and formed on the above photomask blanks 10, and a predetermined pattern is drawn 4 (first drawing) (see FIG. 2B). If necessary, the surface of the semitransmissive film 2 can be subjected to a surface treatment for improving the adhesion with the resist film.

For the coating formation of the resist film 3, known materials such as a slit coater and a spin coater can be used as described above. Either a positive type or a negative type resist can be appropriately used, but this embodiment also describes an example in which the positive type is used.
The formed resist film 3 is drawn with drawing data based on a desired pattern using a drawing device. As in the first embodiment, the drawing apparatus is assumed to have a laser applied.

Then, the drawn resist film 3 is developed to form a resist pattern 3a (first resist pattern) (see FIG. 2C).

Next, the semitransparent film 2a is formed by wet etching (first etching) using the formed resist pattern 3a as an etching mask (see FIG. 2D). .. Again, since the etching target is only the semitransmissive film 2, the etching end point can be set accurately by referring to the etching rate grasped in advance.

The remaining resist pattern 3a is peeled off and removed (see FIG. 2E).
Here, the pattern dimension (CD) of the semitransparent film pattern 2a is measured as needed. Since the pattern edge is only a translucent film, measurement can be performed relatively easily.

In the present embodiment, the etching stopper film 8 is then formed on the entire surface of the transparent substrate 1 on which the semitransparent film pattern 2a is formed on the main surface (see FIG. 2 (f)).
The etching stopper film 8 is made of a material having resistance to the etching agent of the light-shielding film 5 described later. For example, in the etching stopper film 8, the etching rate ratio between the etching solution of the light-shielding film 5 and the light-shielding film 5 is 1/50 or less, preferably 1/100 or less.

Therefore, for example, when a Cr-containing material is used for the light-shielding film 5, a Si-containing material can be used for the etching stopper film 8 or vice versa. In consideration of these, the material of the etching stopper film 8 can be selected from the same materials as those mentioned as the material of the translucent film and the light-shielding film in the first embodiment.

Next, a light-shielding film 5 is further formed on the etching stopper film 8, that is, on the main surface of the transparent substrate 1 on which the semitransparent film pattern 2a and the etching stopper film 8 are formed (FIG. 2 (g). )reference).

Both the etching stopper film 8 and the light-shielding film 5 can be formed by applying the same film forming apparatus as described above.
Further, the material of the light-shielding film 5 may be appropriately selected from those exemplified in the first embodiment, but as mentioned above, in the present embodiment, the material of the light-shielding film 5 is the above half. Mutual etching selectivity with the translucent film 2 is not required.

Next, a resist film 6 (also referred to as a positive type) is applied and formed on the light-shielding film 5, and a predetermined pattern is drawn 7 (second drawing) (see FIG. 2H). The drawing method is the same as in the case of the first drawing described above.
As described above, the in-plane transmittance distribution data obtained by measuring after the film formation of the semi-transmissive film 2 has an unacceptable variation, and an attempt is made to correct this by the pattern of the light-shielding film 5. In this case, the drawing data for the second drawing can be processed.

Next, the drawn resist film 6 is developed to form a resist pattern 6a (second resist pattern) (see FIG. 2 (i)).

Next, the light-shielding film pattern 5a is formed by wet-etching (second etching) the light-shielding film 5 using the formed resist pattern 6a as an etching mask (see FIG. 2 (j)). Since the etching target here is only the light-shielding film 5, there is no difficulty in setting the etching end point by referring to the etching rate grasped in advance. Further, as described above, in the present embodiment, since the etching stopper film 8 is made of a material resistant to the etching agent of the light-shielding film 5, only the light-shielding film 5 is removed by etching in the second etching. Etching.

Then, the remaining resist pattern 6a is peeled off to complete a photomask 30 (multi-gradation photomask) including a transfer pattern including a light-transmitting portion, a light-shielding portion, and a semi-transmissive portion (FIG. 2 (FIG. 2). k) See).

After that, if necessary, the etching stopper film 8 exposed on the surface of the photomask 30 is removed. When removing the etching stopper film 8, it is assumed that there is etching selectivity between the semitransparent film 2 and the etching stopper film 8 in advance. That is, for example, the translucent film 2 and the light-shielding film 5 can both be Cr-containing films, and the etching stopper film 8 can be a Si-containing film, or vice versa. The etching stopper film 8 may be left unremoved if the light transmittance in the semitransparent portion or the translucent portion of the photomask 30 is not particularly affected.

The photomask 30 (multi-gradation photomask) illustrated in the present embodiment also has a light-shielding portion and a semi-transmissive portion adjacent to each other. In the light-shielding portion, a laminated portion of a semi-transmissive film (semi-transmissive film pattern 2a) and a light-shielding film (light-shielding film pattern 5a) is provided in the vicinity of the edge in contact with the semi-transmissive portion with a predetermined constant width. This is done in consideration of the possibility that the light-shielding portion and the semi-transmissive portion are not adjacent to each other and are separated from each other when the alignment deviation occurs in the above two drawings (first drawing and second drawing). It is an alignment margin for absorbing the deviation, and can be formed by processing the drawing data of the first drawing or the second drawing. For example, the width M of the laminated portion (see FIG. 2 (k)) is not particularly limited, but can be, for example, 0.5 to 2 μm, preferably 0.5 to 1 μm. This is also the same as the first embodiment.

Further, the photomask 30 obtained by the present embodiment also has the following features as in the first embodiment.
That is, it is a photomask provided with a transfer pattern including a light-transmitting portion, a light-shielding portion, and a semi-transmissive portion on a transparent substrate, and the transparent substrate surface is exposed in the transparent portion. In the semi-transmissive portion, the light-shielding film is not formed on the transparent substrate, the semi-transmissive film is formed, and in the light-shielding portion, at least the light-shielding film is formed on the transparent substrate. The boundary between the semi-transmissive portion and the light-shielding portion is a photomask characterized in that the cross-section to be etched of the semi-transmissive film is not formed, but the cross-section to be etched of the light-shielding film is formed. is there.

The materials for the semi-transmissive film and the light-shielding film in the photomask are as described above, and in the photomask of the present embodiment, etching is performed between the semi-transmissive film and the light-shielding film. No selectivity is needed.
Further, the edge portion adjacent to the semi-transmissive portion of the light-shielding portion has a laminated portion of the semi-transmissive film and the light-shielding film, and this laminated portion may have a width in the range of 0.5 to 2 μm, for example. As mentioned above.
Further, also in the photomask of the present embodiment, the transfer pattern is, for example, a pattern for manufacturing a display device, and is particularly useful for manufacturing a display device.

As described above, also in the present embodiment, since only each film is etched in each etching step of the semitransmissive film and the light-shielding film, as compared with the case where a plurality of laminated films are continuously etched. Since the etching time is set short, the pattern dimension (CD) fluctuation due to side etching can be reduced. In particular, if a single film is etched in each of the etching steps, the etching time required can be calculated in advance based on the film quality and film thickness, so that dimensional variation due to side etching can be minimized. it can. Further, if the photomask configuration of the present embodiment is adopted, the transmittance management of the semitransmissive film is simpler and more accurate, so that it is possible to manufacture a high-spec display device that realizes high definition and energy saving. , Has great significance.
That is, according to the present embodiment, it is possible to provide a photomask manufacturing method capable of manufacturing a multi-gradation photomask having both finer and higher CD accuracy and transmittance accuracy, and a photomask. ..

Also in the above embodiment, the first transmission control unit is a semi-transmissive unit that partially transmits the exposure light, the second transmission control unit is a light-shielding unit, and the first thin film is a semi-transmissive film and a second. The light-shielding film has been described as an example of the thin film, but the present invention is not limited to this, and excellent effects can be obtained even when other thin films are applied. For example, the first thin film and the second thin film may be semi-transmissive films having predetermined exposure light transmittances, respectively.

Further, also in the photomask of the present embodiment, as a method of applying these first thin films and second thin films, for example, more specifically,
a. The exposure light transmitted through the first transmission control unit having a portion where only the first thin film is formed on the transparent substrate is relative to a representative wavelength of the exposure light transmitted through the transparent portion where the surface of the transparent substrate is exposed. , When the phase difference φ (degree) satisfies φ ≦ 90,
b. The exposure light transmitted through the first transmission control unit has a phase difference φ (degree) of φ ≦ 90 with respect to the representative wavelength of the exposure light transmitted through the light transmission unit, and has a light transmittance Tf ( %) Satisfies 5 ≦ Tf ≦ 60
c. When the phase difference φ (degree) of the exposure light transmitted through the first transmission control unit satisfies 150 ≦ φ ≦ 210 with respect to the representative wavelength of the exposure light transmitted through the light transmission unit,
d. The exposure light transmitted through the first transmission control unit has a phase difference φ (degree) of 150 ≦ φ ≦ 210 with respect to the representative wavelength of the exposure light transmitted through the light transmission unit, and has a light transmittance. When Tf (%) satisfies 5 ≦ Tf ≦ 60
e. The exposure light transmitted through the second transmission control unit having a portion where only the second thin film is formed on the transparent substrate has a phase difference φ (degrees) with respect to the representative wavelength of the exposure light transmitted through the transmissive unit. ) Satisfies 0 <φ ≦ 90
f. The exposure light transmitted through the second transmission control unit has a phase difference φ (degree) of 0 <φ≤90 and a light transmittance with respect to the representative wavelength of the exposure light transmitted through the light transmission unit. When Tf (%) satisfies 5 ≦ Tf ≦ 80
g. The exposure light transmitted through the second transmission control unit has a phase difference φ (degree) of 150 <φ≤210 and a light transmittance with respect to the representative wavelength of the exposure light transmitted through the light transmission unit. When Tf (%) satisfies 5 ≦ Tf ≦ 60
Etc. are useful examples. In either case, the CD accuracy is high and controllable, the effect of the present invention can be obtained, and the optical characteristics of the first transmission control unit and the second transmission control unit can be independently designed. , High quality photomasks with desired design values can be produced.
Further, with respect to the photomask of the present invention according to the second embodiment, as in the first embodiment, the above-mentioned a. ~ G. The configuration such as the above can be appropriately selected to suit the application.

The first embodiment and the second embodiment of the present invention have been described above.
In the above embodiment, the other constituent film is above, below, or in the middle of any of the semitransmissive film 2, the light-shielding film 5, and the etching stopper film 8 as long as the action and effect of the present invention are not impaired. It may exist.

The present invention also provides a method for manufacturing a display device, which comprises, for example, preparing a photomask according to the above embodiment and using an exposure apparatus to transfer a transfer pattern to a transfer target. It is a thing. According to the present invention, by manufacturing a display device using the photomask, it is possible to manufacture a high-spec display device that realizes high definition and energy saving.

That is, there are no restrictions on the use of the photomask of the present invention. For example, it may be provided with transfer patterns used in various layers for manufacturing a panel substrate of a display device (for example, a liquid crystal display or an organic EL display).

For example, those provided with a transfer pattern for manufacturing a TFT (Thin Film Transistor) are exemplified. In a bottom gate type TFT using an amorphous Si or an oxide semiconductor, it is advantageously applied as a photomask used in a step of forming a semiconductor layer and a source / drain layer in a single exposure.

Alternatively, the photomask of the present invention is also advantageously applied when the spacer for a liquid crystal is manufactured by a photosensitive insulating layer. It can be used in the process of forming a stepped structure on the photosensitive insulating film with a single exposure, and a spacer that forms a cell gap and a spacer with a slightly lower height to prevent destruction when pressure is applied are used once. It can be efficiently formed by the exposure of.

As an exposure apparatus for use in the exposure of the photomask of the present invention, for example, the numerical aperture (NA) of the optical system is 0.08 to 0.15, and the coherence factor (σ) is 0.5 to 0.9. A 1x projection exposure method can be used. Alternatively, a proximity exposure method may be applied. Of course, it may be applied to an exposure apparatus for reduced exposure or enlarged exposure.

1 Transparent substrate 2 Semi-transmissive film 3, 6 Resist film 4, 7 Drawing 5 Light-shielding film 8 Etching stopper film 10 Photomask blanks (Substrate with semi-transparent film)
20, 30 photomask

Claims (46)

A method for manufacturing a photomask having a transfer pattern including a light transmitting unit, a first transmission control unit, and a second transmission control unit on a transparent substrate.
A step of preparing a photomask blank having a first thin film having a predetermined exposure light transmittance formed on the transparent substrate, and
The first patterning step of forming the first thin film pattern by etching the first thin film, and
The present invention includes a second patterning step of forming a second thin film on the transparent substrate on which the first thin film pattern is formed and etching the second thin film to form a second thin film pattern.
A method for producing a photomask, which comprises etching only the second thin film in the second patterning step. In the translucent portion, the surface of the transparent substrate is exposed.
The first transmission control unit has a portion on which only the first thin film is formed on the transparent substrate.
The method for manufacturing a photomask according to claim 1, wherein the second transmission control unit has a portion on which only the second thin film is formed on the transparent substrate. The method for producing a photomask according to claim 1 or 2, wherein the first thin film is made of a material that is resistant to the etching agent of the second thin film. The method for producing a photomask according to claim 1 or 2, wherein the first thin film is made of a material that is etched by the etching agent of the second thin film. 4. The fourth aspect of the present invention includes a step of forming an etching stopper film on the transparent substrate on which the first thin film pattern is formed after the first patterning step and before forming the second thin film. The method for manufacturing a photomask described in 1. The photomask according to claim 5, further comprising a step of removing the light-transmitting portion or the etching stopper film of the light-transmitting portion and the first transmission control unit after the second patterning step. Manufacturing method. The method for producing a photomask according to any one of claims 1 to 6, wherein the first thin film is a translucent film that partially transmits exposure light. The exposure light transmitted through the first transmission control unit is characterized in that the phase difference φ (degree) satisfies φ ≦ 90 with respect to the representative wavelength of the exposure light transmitted through the light transmission unit. The method for producing a photomask according to any one of 6 to 6. The exposure light transmitted through the first transmission control unit has a phase difference φ (degree) of φ ≦ 90 with respect to the representative wavelength of the exposure light transmitted through the light transmission unit, and the first transmission control The method for manufacturing a photomask according to any one of claims 1 to 6, wherein the light transmittance Tf (%) of the portion satisfies 5 ≦ Tf ≦ 60. The exposure light transmitted through the first transmission control unit is characterized in that the phase difference φ (degree) satisfies 150 ≦ φ ≦ 210 with respect to the representative wavelength of the exposure light transmitted through the light transmission unit. Item 8. The method for producing a photomask according to any one of Items 1 to 6. The exposure light transmitted through the first transmission control unit has a phase difference φ (degree) of 150 ≦ φ ≦ 210 with respect to the representative wavelength of the exposure light transmitted through the light transmission unit, and has a light transmittance. The method for producing a photomask according to any one of claims 1 to 6, wherein Tf (%) satisfies 5 ≦ Tf ≦ 60. The method for producing a photomask according to any one of claims 1 to 11, wherein the second thin film is a translucent film that partially transmits exposure light. The exposure light transmitted through the second transmission control unit is characterized in that the phase difference φ (degree) satisfies 0 <φ ≦ 90 with respect to the representative wavelength of the exposure light transmitted through the light transmission unit. Item 8. The method for producing a photomask according to any one of Items 1 to 11. The exposure light transmitted through the second transmission control unit has a phase difference φ (degree) of 0 <φ ≦ 90 and a light transmittance with respect to the representative wavelength of the exposure light transmitted through the light transmission unit. The method for producing a photomask according to any one of claims 1 to 11, wherein Tf (%) satisfies 5 ≦ Tf ≦ 80. The exposure light transmitted through the second transmission control unit has a phase difference φ (degree) of 150 <φ≤210 and a light transmittance with respect to the representative wavelength of the exposure light transmitted through the light transmission unit. The method for producing a photomask according to any one of claims 1 to 11, wherein Tf (%) satisfies 5 ≦ Tf ≦ 60. The method for producing a photomask according to any one of claims 1 to 11, wherein the second thin film is a light-shielding film. The method for manufacturing a photomask according to claim 16, wherein a reflection reducing layer for reducing light reflection is provided on the surface portion of the second thin film. The method for producing a photomask according to any one of claims 1 to 17, wherein the photomask blank has an additional constituent film and a resist film on the first thin film. The method for producing a photomask according to claim 18, wherein the adhesion between the additional constituent film and the resist film is higher than the adhesion between the first thin film and the resist film. Prior to the first patterning step, there is a pre-patterning step of etching the additional constituent film to form an additional constituent film pattern.
The method for producing a photomask according to claim 18 or 19, wherein in the first patterning step, the first thin film is etched using the additional constituent film pattern as a mask. The method for producing a photomask according to claim 20, wherein the additional constituent film pattern is removed after the first patterning step and before the second patterning step. On the transparent substrate, a transfer pattern including a light transmitting unit, a first transmission control unit, and a second transmission control unit, and including an adjacent portion adjacent to the first transmission control unit and the second transmission control unit is provided. A method of manufacturing photomasks
A step of preparing a photomask blank having a first thin film having a predetermined exposure light transmittance formed on the transparent substrate, and
A first patterning step in which a first resist pattern is formed in a region to be a first transmission control unit and a first thin film pattern is formed by etching the first thin film.
A film forming step of forming a second thin film on the transparent substrate on which the first thin film pattern is formed, and
It includes a second patterning step of forming a second resist pattern in a region to be a second transmission control unit and etching the second thin film to form a second thin film pattern.
In the second patterning step, a laminated portion in which the second resist pattern is laminated with the first thin film pattern is formed in the adjacent portion.
A method for producing a photomask, which comprises etching only the second thin film using the second resist pattern. In the translucent portion, the surface of the transparent substrate is exposed.
The first transmission control unit includes a portion on which only the first thin film is formed on the transparent substrate.
The method for manufacturing a photomask according to claim 22, wherein the second transmission control unit includes a portion on which only the second thin film is formed on the transparent substrate. The method for producing a photomask according to claim 22 or 23, wherein the width M1 of the laminated portion is in the range of 0.5 to 2 μm. A photomask having a transfer pattern including a light transmitting unit, a first transmission control unit, and a second transmission control unit on a transparent substrate.
The transfer pattern includes a first thin film having a predetermined exposure light transmittance and a second thin film.
In the translucent portion, the surface of the transparent substrate is exposed.
In the first transmission control unit, the second thin film is not formed on the transparent substrate, but the first thin film is formed.
In the second transmission control unit, at least the second thin film is formed on the transparent substrate.
The boundary between the first transmission control unit and the second transmission control unit is characterized in that the cross section to be etched of the first thin film is not formed but the cross section to be etched of the second thin film is formed. mask. In the translucent portion, the surface of the transparent substrate is exposed.
The first transmission control unit has a portion on which only the first thin film is formed on the transparent substrate.
The photomask according to claim 25, wherein the second transmission control unit has a portion on which only the second thin film is formed on the transparent substrate. The photomask according to claim 25 or 26, wherein the first thin film is made of a material that is resistant to the etching agent of the second thin film. The first thin film is made of a material that is etched by the etching agent of the second thin film, and the second transmission control unit is a portion in which an etching stopper film and the second thin film are laminated in this order. The photomask according to claim 25, wherein the photomask is provided. According to any one of claims 25 to 28, the edge portion of the second transmission control unit adjacent to the first transmission control unit has a laminated portion of the first thin film and the second thin film. The photomask described. The photomask according to claim 29, wherein the width M2 of the laminated portion is in the range of 0.5 to 2 μm. The photomask according to any one of claims 25 to 30, wherein the first thin film is a translucent film and the second thin film is a light-shielding film. A photomask having a transfer pattern including a light transmitting unit, a first transmission control unit, and a second transmission control unit on a transparent substrate.
The transfer pattern includes a first thin film pattern composed of a first thin film having a predetermined exposure light transmittance and a second thin film pattern composed of a second thin film.
In the translucent portion, the surface of the transparent substrate is exposed.
The first transmission control unit has a portion on the transparent substrate in which only the first thin film pattern is formed.
The second transmission control unit has a portion on the transparent substrate in which only the second thin film pattern is formed.
A photomask characterized by having a laminated portion in which the first thin film pattern and the second thin film pattern are laminated, sandwiched between the first transmission control unit and the second transmission control unit. The photomask according to claim 32, wherein the width M2 of the laminated portion is in the range of 0.5 to 2 μm. The photomask according to claim 32 or 33, wherein the edges of the first thin film pattern and the second thin film pattern have a wet-etched cross section of the first thin film and the second thin film, respectively. The photomask according to any one of claims 32 to 34, wherein the first thin film is a translucent film that partially transmits exposure light. 32. The exposure light transmitted through the first transmission control unit is characterized in that the phase difference φ (degree) satisfies φ ≦ 90 with respect to the representative wavelength of the exposure light transmitted through the light transmission unit. The photomask according to any one of 34 to 34. The exposure light transmitted through the first transmission control unit has a phase difference φ (degree) of φ ≦ 90 with respect to the representative wavelength of the exposure light transmitted through the light transmission unit, and has a light transmittance Tf ( %) Is the photomask according to any one of claims 32 to 34, wherein 5 ≦ Tf ≦ 60 is satisfied. The exposure light transmitted through the first transmission control unit is characterized in that the phase difference φ (degree) satisfies 150 ≦ φ ≦ 210 with respect to the representative wavelength of the exposure light transmitted through the light transmission unit. Item 8. The photomask according to any one of Items 32 to 34. The exposure light transmitted through the first transmission control unit has a phase difference φ (degree) of 150 ≦ φ ≦ 210 with respect to the representative wavelength of the exposure light transmitted through the light transmission unit, and has a light transmittance. The photomask according to any one of claims 32 to 34, wherein Tf (%) satisfies 5 ≦ Tf ≦ 60. The photomask according to any one of claims 32 to 39, wherein the second thin film is a light-shielding film. The photomask according to any one of claims 32 to 39, wherein the second thin film is a translucent film that partially transmits exposure light. The exposure light transmitted through the second transmission control unit is characterized in that the phase difference φ (degree) satisfies 0 <φ ≦ 90 with respect to the representative wavelength of the exposure light transmitted through the light transmission unit. Item 3. The photomask according to any one of Items 32 to 39. The exposure light transmitted through the second transmission control unit has a phase difference φ (degree) of 0 <φ ≦ 90 and a light transmittance with respect to the representative wavelength of the exposure light transmitted through the light transmission unit. The photomask according to any one of claims 32 to 39, wherein Tf (%) satisfies 5 ≦ Tf ≦ 80. The exposure light transmitted through the second transmission control unit has a phase difference φ (degree) of 150 <φ≤210 and a light transmittance with respect to the representative wavelength of the exposure light transmitted through the light transmission unit. The photomask according to any one of claims 32 to 39, wherein Tf (%) satisfies 5 ≦ Tf ≦ 60. The photomask according to any one of claims 25 to 44, wherein the transfer pattern is a pattern for manufacturing a display device. The photomask obtained by the method for producing a photomask according to any one of claims 1 to 24 or the photomask according to any one of claims 25 to 44 is prepared and used for the transfer using an exposure apparatus. A method for manufacturing a display device, which comprises a step of transferring a pattern to a transfer target.

Images