KR102367141B1 - Photomask, method for manufacturing photomask, and method for manufacturing display device - Google Patents

Abstract

A photomask capable of reliably and stably transferring a fine pattern onto an object to be transferred is provided.
A photomask for manufacturing a display device has a transfer pattern including a light-transmitting portion 10 , a light-shielding portion 20 , and a semi-transmissive portion 30 . The light-transmitting part 10 is formed by exposing a transparent substrate. The light-shielding portion 20 is formed in contact with the outer edge of the complete light-shielding portion 21 with at least a light-shielding film formed on a transparent substrate, and a width formed by forming a semi-transmissive rim forming film on a transparent substrate. It has a rim portion 22 of γ. The semi-transmissive portion 30 is sandwiched between the light-shielding portions 20 and a transparent substrate is exposed with a predetermined width α. The width α is set so that the exposure light transmittance of the semi-transmissive portion 30 is smaller than the exposure light transmittance of the translucent portion 10 . In the rim formation film, the transmittance Tr with respect to the light of the representative wavelength of the exposure light is 5 to 60%, and the phase shift amount with respect to the light of the representative wavelength is 90 degrees or less.

Description

A photomask, the manufacturing method of a photomask, and the manufacturing method of a display device TECHNICAL FIELD

The present invention relates to a photomask for manufacturing an electronic device, and particularly to a photomask suitable for manufacturing a display device, and a manufacturing method thereof. The present invention also relates to a method of manufacturing a display device using the photomask. Here, the display device includes a device for constituting the final display device product.

For example, Patent Document 1 describes a multi-gradation photomask having a light-shielding region that blocks exposure light, a light-transmitting region that transmits exposure light, and a semi-transmissive region that transmits part of the exposure light. When a desired pattern is transferred to a resist film (positive photoresist) on an object using such a multi-gradation photomask, the amount of exposure light irradiated through the semi-transmissive region is less than the amount of exposure light irradiated through the transmissive region . For this reason, when a resist film is developed, a resist pattern with which the residual film value (residual film thickness) of a resist film differs according to the amount of irradiated light is formed. That is, the resist residual film value of the region irradiated with exposure light through the semi-transmissive region of the multi-gradation photomask becomes thinner than the resist residual film value of the region irradiated with exposure light through the light-shielding region.

As described above, if a multi-gradation photomask capable of forming a resist pattern having a different resist residual film value depending on the region is used, the number of photomasks used in the manufacture of a display device can be reduced, increasing production efficiency, and cost can lower

The said multi-gradation photomask is used for manufacture of the thin film transistor (TFT) applied to display apparatuses, such as a liquid crystal display device and an organic electroluminescence (EL) display device. In this case, the source/drain (S/D) electrode of the TFT and the channel region therebetween can be formed using one photomask in one photolithography process.

Japanese Patent Laid-Open No. 2010-197800

Currently, in display devices, the trend toward higher resolution is remarkable with an increase in pixel density. Moreover, in a portable terminal, especially the performance of brightness and power saving is calculated|required. And in order to implement|achieve these, refinement|miniaturization is strongly calculated|required also for the pattern of the photomask used for a manufacturing process.

However, in the field of photomasks for semiconductor device (LSI) manufacturing, in which the degree of integration is high compared to the display device and the pattern miniaturization has progressed remarkably, in order to obtain high resolution, the exposure device has a high numerical aperture NA (for example, 0.2). There is a case in which the wavelength of exposure light has been shortened by applying an optical system of NA). As a result, in this field, excimer lasers of KrF and ArF (single wavelengths of 248 nm and 193 nm, respectively) have come to be widely used.

On the other hand, in the field of lithography for manufacturing a display device, there has not been a trend in which the method is applied to improve resolution. For example, the NA (numerical aperture) of the optical system of the exposure apparatus used in this field|area is about 0.08-0.15. In addition, as for the exposure light source, i-line, h-line, or g-line are mainly used, and by using a light source having a wavelength region mainly including these, a large area (for example, a square with one side of the main surface of 300 to 2000 mm) is obtained. There is a strong tendency to obtain the amount of light to be irradiated and to focus on production efficiency and cost.

As an effective means of improving production efficiency, the multi-gradation photomask described in Patent Document 1 is very useful. For example, a process of forming TFTs, that is, S/D (source/drain) and channels for controlling the driving of the display device, is an essential part of the production process of the display device, but a multi-gradation photomask can be used. On the other hand, along with strong demands for image quality, operating speed, power saving, and the like of portable terminals, the demand for pattern miniaturization is remarkable. For example, the design dimension of the channel length in the TFT tends to become smaller and smaller.

Therefore, there is a strong demand for a photomask capable of reliably and efficiently transferring a pattern having such a high degree of difficulty.

Therefore, a resist pattern having a good profile is obtained by reliably and stably transferring a finer pattern than in the past by incorporating a new function into a photomask while taking advantage of the performance of an exposure apparatus used for display device manufacturing. About the means which can be formed, the present inventors studied and completed this invention.

(first aspect)

A first aspect of the present invention is

A photomask for manufacturing a display device having a transfer pattern comprising a light-transmitting portion, a light-shielding portion and a semi-transmissive portion for forming a resist pattern having a plurality of different residual film values on a transfer object by exposure, the photomask comprising:

The light-transmitting part is made by exposing a transparent substrate,

The light blocking unit,

a complete light-shielding portion in which at least a light-shielding film is formed on the transparent substrate;

a rim portion having a width γ formed in contact with an outer edge of the complete light shielding portion and formed with a semi-transmissive rim forming film on the transparent substrate;

The semi-transmissive part is sandwiched between the light-shielding parts, and the transparent substrate is exposed to a predetermined width α,

The width α is set so that the light transmittance of the semi-transmissive part is smaller than the exposure light transmittance of the light-transmitting part;

The said rim formation film is a photomask whose transmittance|permeability Tr with respect to the light of the representative wavelength of exposure light is 5 to 60 %, and the phase shift amount with respect to the light of the said representative wavelength is 90 degrees or less.

(Second aspect)

A second aspect of the present invention is

The photomask according to the first aspect, wherein the width γ of the rim is 0.1 μm≤γ<1.0 μm.

(Third aspect)

A third aspect of the present invention is

The photo according to the first or second aspect, wherein the transfer pattern forms a removal pattern having a pattern width of 1 to 4 µm on a transfer object corresponding to the semi-transmissive portion by an exposure apparatus for display device manufacturing. it's a mask

(4th aspect)

A fourth aspect of the present invention is

It is the photomask in any one of said 1st thru|or 3rd aspect for the said transcription|transfer pattern is for being exposed with the broad-wavelength light source within the range of 300-500 nm by the exposure apparatus for display apparatus manufacture.

(5th aspect)

A fifth aspect of the present invention is

The said transfer pattern is a pattern for thin film transistor manufacturing, The said semi-transmissive part is the photomask in any one of said 1st thru|or 4th aspect corresponding to the channel part of a thin film transistor.

(Sixth aspect)

A sixth aspect of the present invention is

A method of manufacturing a photomask having a transfer pattern comprising a light-transmitting portion, a light-shielding portion and a semi-transmissive portion for forming a resist pattern having a plurality of different residual film values on a transfer object by exposure, the method comprising:

A step of preparing a photomask blank in which a rim forming film and a light-shielding film are laminated in this order on a transparent substrate;

a first patterning step of using a resist pattern formed on the light-shielding film as an etching mask and patterning the light-shielding film using an etchant for a light-shielding film;

a second patterning process of patterning the rim-forming film using the etchant for the rim-forming film;

a third patterning step of side-etching the light-shielding film by using the resist pattern as an etching mask and using an etchant for a light-shielding film;

A peeling process of peeling the resist pattern

It is a method of manufacturing a photomask for manufacturing the photomask according to any one of the first to fifth aspects having a.

(Seventh aspect)

A seventh aspect of the present invention is

A method of manufacturing a display device, comprising the steps of: preparing the photomask according to any one of the first to fifth aspects;

A step of transferring the transfer pattern onto a transfer target by exposing the photomask using an exposure apparatus for manufacturing a display device

A method of manufacturing a display device having

(8th aspect)

The eighth aspect of the present invention is

The method for manufacturing the display device according to the seventh aspect, wherein the display device includes a thin film transistor.

According to the present invention, when a transfer pattern of a photomask is transferred onto a transfer object, an optical image having an excellent profile can be stably formed, thereby contributing to improvement in performance and yield of a display device.

BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing which illustrates the principal part of the photomask which concerns on one Embodiment of this invention, (a) is a figure which shows an example of the transfer pattern, (b) is a partial enlarged view of the transfer pattern. .
Fig. 2 is an explanatory diagram showing an example of a transfer pattern, (a) is a diagram showing a pattern example of the photomask of Comparative Example 1, (b) is a diagram showing a pattern example of the photomask of Reference Example 1 Drawing (c) is a figure which shows the pattern example of the photomask of Example 1 of this invention.
3 is an explanatory diagram showing simulation results for evaluating the transfer performance of the photomask of Example 1 of the present invention, and (d-1) and (d-2) are diagrams showing simulation results for Comparative Example 1 , (d-3) and (d-4) are diagrams showing simulation results for Reference Example 1 and Example 1.
4 is a side cross-sectional view illustrating a resist pattern formed on an object to be transferred.
5 : is explanatory drawing which shows the procedure of the manufacturing method of the photomask which concerns on one Embodiment of this invention, (a) is a figure which shows an example of a photomask blank, (b) shows an example of pattern drawing (c) is a diagram showing an example of the first and second etching, (d) is a diagram showing an example of the third etching, (e) is a diagram showing an example of resist pattern peeling.
6 is an explanatory diagram illustrating a transfer pattern (channel width 5.0 µm) formed on a conventional photomask, (a) is a diagram showing an example of the transfer pattern, (b) is the transfer pattern It is a figure which shows the example of the optical image (transfer image) formed on the to-be-transferred object.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of the photomask which concerns on this invention, and its manufacturing method is described.

In Fig. 6(a), a transfer pattern (channel width) formed in a photomask for manufacturing a channel/S/D layer (hereinafter, simply referred to as “S/D layer”) of TFT, described in Patent Document 1 above. 5.0 μm). This photomask is a multi-gradation photomask provided with the light-shielding part 120 , the semi-transmissive part 130 , and the light-transmitting part 110 . A semi-transmissive film having a transmittance Tr of 40% is used for the semi-transmissive portion 130 . In addition, when this is exposed with an exposure apparatus (NA = 0.08, coherence factor σ = 0.8, i-line: h-line: g-line = 1:1:1), the optical image (transfer image) formed on the object to be transferred is , is (b) of FIG. 6 . In Fig. 6B, a portion with a large amount of reaching light is displayed in a bright color (white to gray), and a portion having a small amount of light is displayed in a dark color (black), respectively.

However, according to the studies of the present inventors, when a multi-gradation photomask in which only a semi-transmissive film is formed on the transparent substrate of the channel region as described above is exposed and the transfer pattern is transferred onto the transfer object, the image A problem arose in the shape of the resist pattern to be formed. That is, in the photomask, since a semi-transmissive film having a width equal to the width of the channel region is sandwiched between the light blocking portions 120, at the end (edge portion) of the portion corresponding to the channel region of the resist pattern, A significant slope was generated on the side surface of the resist pattern. Then, when a film (a thin film to be processed) formed on the surface of a display panel substrate or the like is processed using this resist pattern as an etching mask, a fine, precise, and dense CD (pattern width) is formed on the film. It is not easy to do. For this reason, it turned out that it is difficult to form stably the channel part of fine dimensions.

Then, the present inventors investigated which optical image (light intensity distribution) was formed on the to-be-transferred object according to the shape of the transfer pattern which the photomask which forms a channel part has. For example, if it is possible to obtain a photomask capable of forming a resist pattern having a more vertical side shape (to be described later, a larger inclination angle θ and close to 90 degrees), a pattern having a fine width (for example, a wider This small channel portion) can be formed more stably and reliably. In addition, if the inclination angle θ of the side surface of the resist pattern can be finely adjusted to a desired value of 90 degrees or less, a fine pattern can be formed with high precision and a resist pattern capable of fine adjustment of CD can be formed.

Fig. 1 illustrates an essential part of a photomask according to an embodiment of the present invention.

This photomask is a so-called multi-gradation photomask (also called gradation photomask, gray tone mask, etc.) that forms a resist pattern having a plurality of different residual film values on an object to be transferred by exposure using an exposure apparatus. .

In addition, here, the pattern design for forming the S/D layer of TFT used for a display apparatus (a liquid crystal display device, an organic electroluminescent display apparatus, etc.) by one photolithography process is shown as an example, for example.

The transfer pattern included in this photomask is formed on a transparent substrate, and has a light transmitting portion 10 , a light blocking portion 20 , and a semi-transmissive portion 30 . That is, it is a photomask having three or more grayscales.

In the photomask of the present invention, a removal pattern having a pattern width of about 1 to 4 μm can be formed at the position of the transfer pattern on a transfer target (eg, a display panel substrate) corresponding to the semi-transmissive portion 30 . . For example, it can be applied as a photomask for forming a channel width (Cp (µm)) of this dimension. In this embodiment, it is assumed and demonstrated that a fine channel width less than 3 micrometers is formed. For example, it is applicable to the manufacture of a TFT in which 1≤Cp<3 (µm), more specifically 1.5≤Cp<3 (µm).

The light-transmitting part 10 is formed by exposing the transparent substrate surface. This part is a part which has a dimension wide enough with respect to the resolution performance of an exposure apparatus. For example, it has a dimension greater than 5 μm, more specifically a dimension greater than 10 μm.

The light-shielding portion 20 includes a complete light-shielding portion 21 having a predetermined width β (μm) and a rim portion 22 having a predetermined width γ (μm). The complete light blocking portion 21 is formed by forming a light blocking film on a transparent substrate. The rim portion 22 is formed by forming a rim forming film on the transparent substrate so as to be in contact with the outer edge of the complete light shielding portion 21 .

Of these, the complete light-shielding portion 21 has at least a light-shielding film formed on a transparent substrate. The optical density OD (Optical Density) of the light-shielding film is 2 or more, more preferably 3 or more. In the complete light-shielding portion 21 , a light-shielding film and another film may be laminated. For example, a rim formation film (described later) may be laminated on the lower layer side or the upper layer side of the light shielding film. Preferably, the rim forming film and the light shielding film are laminated in this order.

The width β of the complete light shielding portion 21 is preferably 1.5 µm or more. When the width β is too narrow, it becomes difficult to function as the complete light-shielding portion 21 . The width β of the complete light shielding portion 21 is more preferably 2 µm or more, for example, 1.5 to 4 µm, more specifically 2.0 to 3.5 µm.

Of the light-shielding portions 20, the rim portion 22 is formed by forming a semi-transmissive rim-forming film that partially transmits exposure light on a transparent substrate. The rim portion 22 is formed with a predetermined width (hereinafter, rim width) γ along the outer edge of the complete light shielding portion 21 .

The rim width γ can be 0.1≤γ<1.0 (µm). The rim width γ can be more preferably 0.1≤γ<0.5 (µm).

If the rim width γ is too wide, the effect of improving the inclination angle θ, which will be described later, becomes small, and it is difficult to form a finer channel or tends to lead to a loss of the film thickness of the resist pattern formed on the transfer object. there is. When the rim width γ is too small, the effect of improving the depth of focus (DOF), which will be described later, during transfer becomes insufficient.

The rim width γ can more preferably be 0.2≤γ<0.4 (μm).

In FIG. 1, the rim part 22 is formed in contact with all the outer edges of the complete light-shielding part 21. As shown in FIG. However, if the rim portion 22 is formed at least in the region where the light-shielding portion 20 is adjacent to the semi-transmissive portion 30 , the rim portion 22 does not necessarily need to be formed on the outer edge of the other regions. That is, it is preferable that the rim part 22 is formed in the area|region corresponding to the channel part of TFT among the outer periphery of the complete light-shielding part 21. As shown in FIG. More preferably, the rim portion 22 has the above width, is in contact with all the outer edges of the complete light shielding portion 21 in the photomask surface, and is formed with a uniform width.

As the exposure light transmittance Tr (%) of the rim forming film for forming the rim 22 , 5 ? Tr ? 60 (%) is applicable. This is the transmittance based on the transparent substrate (100%), and it is the transmittance|permeability with respect to the representative wavelength of the light contained in exposure light.

The exposure light transmittance Tr is preferably 5 ≤ Tr < 40 (%), more preferably 5 ≤ Tr < 30 (%).

When the value of the transmittance Tr is too small, there arises a problem that Eop (required exposure amount) for obtaining a desired channel width becomes large. Also, when the value of the transmittance Tr is too large, it becomes difficult to form a fine channel width on the transfer target body.

However, when the transmittance Tr is somewhat large in the above range (for example, 20 ≤ Tr ≤ 40 (%)), the inclination of the cross-section of the resist pattern formed on the transfer object becomes gentle, and the inclination angle θ described later becomes fine. If you want to make adjustments, that's an advantage.

Here, as the exposure light, light having a wavelength within the range of 300 to 500 nm is applied, and specifically, it is preferable to include any of i-line, h-line, and g-line. More specifically, a light source including a plurality of wavelengths (also referred to as a broad-wavelength light source) may be used, and for example, in a wavelength region including two wavelengths or all three wavelengths among i-line, h-line, and g-line. In some cases, a light source that spans is used. This is preferable from the viewpoint of production efficiency of the display device. Among these, the representative wavelength can be any wavelength in the wavelength range included in the exposure light, for example, i-line.

Moreover, as for the rim formation film for forming the rim part 22, it is more preferable that the phase shift amount with respect to exposure light is 90 degrees or less, and it is 3-60 degrees. In the photomask according to the present invention, a phenomenon in which the transmitted light of the light transmitting portion 10 and the rim portion 22 is canceled by mutual interference is suppressed, and there is no problem of increasing the dose required for exposure.

The semi-transmissive portion 30 is formed by exposing a transparent substrate to a predetermined width. As shown in FIG. 1 , the semi-transmissive portion 30 is sandwiched between the light-shielding portions 20 , and more specifically, the rim portion 22 of the light-shielding portion 20 is sandwiched from two opposing directions. there is.

The width α (μm) of the semi-transmissive portion 30 is set so that the exposure light transmittance of the semi-transmissive portion 30 is smaller than that of the light transmitting portion 10 when the photomask is exposed with an exposure apparatus for manufacturing a display device. there is. That is, the semi-transmissive portion 30 has a structure in which the surface of the transparent substrate is exposed similarly to the transparent portion 10 , but the peak of the light intensity distribution formed by the transmitted light on the transfer target is Since it is lower than the light intensity of transmitted light, it functions as the semi-transmissive part 30 . Therefore, when the transmittance of the transparent portion 10 having a sufficient area is 100%, and the peak of the transmittance distribution formed on the transfer target in the region corresponding to the semi-transmissive portion 30 is Ta (%), Ta is It can be set as 30 to 70 %, and it is more preferable that it is 40 to 60 %.

The width α of the semi-transmissive portion 30 may be, for example, 0.8≤α<3.0 (µm), more specifically, 1.0≤α<2.0 (µm).

Such a width is effective because it functions as the semi-transmissive portion 30 during exposure. In addition, a narrow pattern (here, the width of the channel portion formed on the object to be transferred) can be stably formed by the semi-transmissive portion 30 .

Further, if necessary, by finely adjusting the rim width γ and the transmittance Tr of the rim forming film, the inclination angle of the cross section of the resist pattern formed on the transfer object (inclination angle θ to be described later) is adjusted to a desired value, and the fine CDs can be easily obtained.

With the photomask of the present invention having such a semi-transmissive portion 30 , a TFT having the channel width Cp can be formed on an object to be transferred.

In addition, the drawings accompanying this specification are schematic diagrams for easy understanding, and the dimension etc. of a pattern do not necessarily correspond with the actual scale.

The use of the photomask of the present invention is not particularly limited. For example, it is used for manufacturing thin film transistors (TFTs) for LCD (Liquid Crystal Display) or organic EL displays, and is particularly suitable for multi-gradation photomasks used when processing S/D layers and semiconductor layers by one photolithography process. , can be advantageously applied.

Hereinafter, what kind of transfer performance the photomask having the rim portion 22 as described above has is shown in Examples. In addition, for comparison, it shows also about a comparative example and a reference example together.

(Example)

In order to confirm the effect of the photomask of the present invention, the following optical simulation was performed with respect to the photomask shown in FIG. 2 . The three photomasks shown in FIGS. The light-shielding portion has an optical density OD (Optical Density) of 3 or more, and the light-transmitting portion is formed by exposing a transparent substrate, and its dimensions are sufficiently wide with respect to the resolution limit of the exposure machine. The structure of the semi-transmissive part is comprised as follows, respectively.

FIG. 2A shows a photomask of Comparative Example 1. As shown in FIG. This photomask has the same configuration as in Patent Document 1, that is, a light-shielding portion 120 in which a light-shielding film is formed on a transparent substrate, a light-transmitting portion 110 in which the transparent substrate is exposed, and a semi-transmissive film formed on the transparent substrate. It has a semi-transmissive part 130 . The exposure light transmittance Tr of the semitransmissive film used in this photomask is 55%, and the width d1 of the semitransmissive part 130 is 4.5 micrometers. In addition, the phase shift amount of the semitransmissive film was made into 0 degree|times.

Fig. 2B shows the photomask of Reference Example 1. As shown in Figs. This photomask has the light-shielding portion 220 and the light-transmitting portion 210 similar to those of Comparative Example 1, while having the semi-transmissive portion 230 with the transparent substrate exposed. The width d2 of the semi-transmissive portion 230 is set to 2.15 μm so that the exposure light transmittance of the semi-transmissive portion 230 is lower than the transmittance of the light transmitting portion 210 .

Fig. 2(c) shows a photomask of Example 1 of the present invention. As described above, this photomask has a light-shielding portion 20 , a light-transmitting portion 10 , and a semi-transmissive portion 30 on a transparent substrate, and the light-shielding portion 20 is a complete light-shielding portion 21 and a rim portion 22 . ) and is composed of

Here, the translucent portion 30 has a width α of 2.00 μm and is formed by exposing a transparent substrate. For the rim portion 22 of the light shielding portion 20, the rim width γ is 0.2 µm, and a semi-transmissive film (ie, a rim formation film) having a transmittance Tr of 10% was used for forming the rim. The phase shift amount of the rim formation film was made into zero.

The simulation conditions and evaluation items were as follows (refer to FIG. 3).

(Simulation condition)

ㆍExposure optical system: NA = 0.085, σ = 0.9 (assuming equal magnification projection exposure apparatus for display device manufacturing)

ㆍIntensity of exposure wavelength: i-line: h-line: g-line = 1:0.8:0.95

(evaluation item)

(1) Panel CD (㎛)

The resist pattern (refer to FIG. 4) formed on the to-be-transferred object has the cross-sectional shape of "valley" corresponding to a channel part. Here, the initial set resist thickness of the unexposed part is 24000 Å, and the target resist residual film value (Z in FIG. ) is 6800 Å.

In addition, there are two portions on both sides of the valley where the thickness of the resist pattern is 12000 Å (that is, 1/2 of the thickness of the unexposed portion). Assuming that it corresponds to Cp, its dimension was calculated and it was referred to as Panel CD (μm).

That is, when a photomask user forms a channel part using the photomask of this embodiment, it is assumed that the resist pattern formed on the to-be-transferred object is reduced to 1/2 thickness.

(2) The inclination angle θ of the cross section of the resist pattern in the portion of the resist pattern having a residual film value of 12000 angstroms (1/2 with respect to the thickness of the unexposed portion) was determined.

(3) DOF (depth of focus, μm)

The range of the defocus for transferring on the transfer target in the range of ±10% with respect to the target dimension was calculated|required.

(4) EL (Exposure Latitude)

The amount of change in exposure energy to be transferred onto the object to be transferred in a range of ±10% with respect to the target dimension was determined.

(Evaluation results)

3(d-1) to (d-4) show the simulation results.

First, when the photomask of Comparative Example 1 shown in Fig. 2(a) is transferred, the pattern formed on the transfer object has a Panel CD exceeding 3.39 µm, and a finer CD portion (e.g., TFT channel) was found to be difficult to form. In addition, it is considered that the inclination angle θ of the resist pattern formed on the transfer object is small, and the sharpness of the cross-sectional inclination is related (refer to (d-1) and (d-2) of Fig. 3).

In Fig. 2(b), in Comparative Example 1, instead of the semi-transmissive film formed over the entire area of the semi-transmissive portion 130, a transparent substrate is exposed to a minute predetermined width to form the semi-transmissive portion 230. Reference Example 1 is shown. When the photomask of Reference Example 1 was transferred, the numerical value of Panel CD could be significantly reduced compared to Comparative Example 1, and it was found that a fine CD could be achieved. In addition, it was found that the cross-sectional inclination of the resist pattern was also suppressed (see FIGS. 3 (d-3) and (d-4)).

However, in Reference Example 1, it was found that the value of DOF was low and the margin for defocusing of the exposure apparatus was narrow (refer to FIG. 3 (d-4)).

DOF is an allowable range of defocus that satisfies the allowable range of CD, and is related to the flatness of a photomask and a transfer target substrate. In particular, in display device manufacturing, the size of the photomask is large (for example, a square with one side of the main surface of 300 to 2000 mm), and the panel substrate used as a transfer object is also larger (for example, 1000 on one side of the main surface). to 3400 mm square), it is difficult to process it into an ideal plane, and it is easy to cause fluctuations in flatness. In other words, in order to obtain a substrate having excellent flatness, a large number of steps and costs are required. Therefore, it is very important to secure a margin for defocus.

Next, using the photomask of Example 1 of the present invention shown in FIG. 2C , a simulation was performed in the same manner as in Reference Example 1 to obtain a Panel CD having a diameter of about 2.4 µm. This photomask is in contact with the outer edge of the complete light-shielding portion 21 having an optical density of OD 3 or higher, and a semi-transmissive rim portion 22 is formed (refer to Fig. 3 (d-3)).

In the transferred image with the photomask of Example 1, an extremely fine TFT channel of about 2.4 μm can be formed similarly to Reference Example 1, and the angle θ of the cross section of the resist pattern is sufficiently large compared to Comparative Example 1. close), the CD fluctuation is small, and the CD distribution in the plane can be made small (refer to Fig. 3 (d-4)).

Moreover, the DOF value of the photomask of Example 1 exceeds 48 micrometers, and it is equipped with sufficient margin with respect to the defocusing at the time of exposure (refer FIG.3(d-4)).

In addition, the numerical value of the exposure margin EL is remarkably improved as compared with Comparative Example 1 and Reference Example 1 (refer to Fig. 3 (d-4)).

Since EL is a margin for energy fluctuations due to exposure light, it can be seen that, when this numerical value is large, transfer performance with higher CD precision can be obtained and the yield can be maintained high. In particular, in an exposure apparatus for manufacturing a display device, it is not easy to irradiate a large area with a uniform amount of light, so a photomask having a large EL is significant.

That is, when the photomask of the present invention is used, a pattern having a fine CD with a panel CD of less than 2.5 μm can be formed on a transfer object, and the exposure light amount or focus margin at that time is large, so that production stability and It was found to contribute to the yield. This means that when the transfer pattern of the photomask of the present invention is transferred onto an object to be transferred, an optical image having an excellent profile can be stably formed, thereby contributing to the improvement of the performance and yield of the display device. . In other words, according to the photomask of the present invention, a finer pattern than before is reliably and stably transferred onto a transfer object by adding a new function to the photomask while taking advantage of the performance of the exposure apparatus used for manufacturing a display device. Thus, a resist pattern having a good profile can be formed.

The photomask of this invention can be manufactured by the following manufacturing methods. The procedure of such a manufacturing method is demonstrated, referring FIG.

1. Prepare a photomask blank.

Specifically, when manufacturing a photomask, first, a photomask blank 50 as shown in FIG. 5A is prepared. In the photomask blank 50, a rim forming film 52 and a light blocking film 53 are formed in this order on a transparent substrate 51 made of glass or the like, and a first photoresist film (here, a positive type) ) (54) may be applied.

The rim forming film 52 has a transmittance as described for the transmittance Tr with respect to light having a representative wavelength of the exposure light. The phase shift amount of the rim formation film 52 is 90 degrees or less, More preferably, it is 3-60 degrees.

The rim forming film 52 is preferably made of a wet-etchable material, and preferably has etching selectivity with the light-shielding film material.

The rim forming film 52 may be, for example, a Cr compound (oxide, nitride, carbide, oxynitride, or oxynitride carbide) or may be the compound of Si. The rim forming film 52 may be a silicide of any metal among Mo, W, Ta, Ti, and Zr, or the compound of the silicide. As a film forming method of the rim forming film 52, a well-known method, such as a sputtering method, is applicable.

On the rim forming film 52 of the photomask blank 50 , a light blocking film 53 is formed. As a film-forming method of the light-shielding film 53, a well-known means, such as a sputtering method, can be applied similarly.

The material of the light shielding film 53 may be Cr or a compound thereof (oxide, nitride, carbide, oxynitride, or oxynitride carbide), or a metal silicide containing Mo, W, Ta, Ti, or the silicide described above. A compound may be sufficient.

However, the material of the light shielding film 53 is preferably a material that can be wet-etched like the rim formation film 52 and has etching selectivity with respect to the material of the rim formation film 52 . That is, it is preferable that the light-shielding film 53 has resistance to the etching agent of the rim-forming film 52 , and the rim-forming film 52 has resistance to the etching agent of the light-shielding film 53 .

2. The drawing apparatus draws by predetermined pattern data.

Specifically, as shown in FIG. 5B , pattern writing is performed on the first photoresist film 54 of the photomask blank 50 . For pattern writing, laser writing can be applied.

3. The first photoresist film 54 is developed, and the light shielding film 53 and the rim forming film 52 are etched.

Specifically, as shown in FIG. 5(c), the first photoresist film 54 is developed, and corresponding to the transmissive part 10 (FIG. 1) and the semi-transmissive part 30 (FIG. 1). A resist pattern 55 having an opening in the position is formed. Then, using the resist pattern 55 as an etching mask, the light-shielding film 53 is etched (first etching) using an etchant for the light-shielding film to form a light-shielding film pattern (first patterning step). Further, using the patterned light-shielding film pattern as an etching mask, the rim formation film 52 is etched (second etching) using an etchant for the rim formation film to form a rim formation film pattern (second patterning step). A well-known etching agent is used for each etching of the light shielding film 53 and the rim formation film 52 according to a material. At this time, it is preferable to apply wet etching. Thereby, the transparent substrate 51 is exposed in the part corresponding to the translucent part 10 and the semi-transmissive part 30 .

4. Side etching of the light-shielding film 53 (light-shielding film pattern) is performed.

Specifically, as shown in Fig. 5(d), an etchant for a light-shielding film material is applied again, and the resist pattern 55 is used as an etching mask to form the side of the light-shielding film 53 (light-shielding film pattern). Etching (third etching) is performed (third patterning process). Thereby, the rim part 22 is formed.

5. The resist pattern 55 is peeled off.

Specifically, as shown in Fig. 5E, the resist pattern 55 is removed by peeling. Thereby, the transparent substrate 51 has the light-transmitting part 10 (FIG. 1), the light-shielding part 20, and the semi-transmissive part 30, of which the light-shielding part 20 is the complete light-shielding part 21 and the rim part. A photomask configured with (22) is completed. More specifically, the light-shielding portion 20 includes at least a complete light-shielding portion 21 on which the light-shielding film 53 is formed, and a rim portion 22 formed by the rim-forming film 52, and a semi-transmissive portion ( 30 is sandwiched between the light blocking portions 20 to expose the transparent substrate 51 , and a photomask having a configuration in which the transmittance of the exposure light is set to be smaller than the transmittance of the light transmitting portion 10 is completed.

As mentioned above, it is preferable to manufacture the photomask of this invention by making a drawing process only once. In addition, according to this manufacturing method, although it is necessary to pattern two films, the light-shielding film 53 and the rim forming film 52, respectively, the alignment misalignment due to a plurality of times of drawing does not occur. ) can be uniformly formed over the inside of the photomask surface.

The present invention includes a method for manufacturing a display device, which comprises transferring a transfer pattern onto a transfer target by performing exposure by an exposure apparatus using the photomask. In addition, the display device here includes the module and components which comprise a part of a display device.

By exposing and developing the photomask of the present invention with an exposure apparatus, a three-dimensional resist pattern having portions having different residual film values is formed on the transfer target. For example, when a positive resist is used, a resist residual film is not formed at a position corresponding to the light-transmitting part, but a resist residual film having a predetermined thickness H1 is formed at a position corresponding to the light-shielding part, and the semi-transmissive part At a position corresponding to , a resist residual film having a thickness H2 smaller than H1 is formed.

As an exposure apparatus used for this manufacturing method, the thing of the same magnification projection exposure system with NA of 0.08-0.2 and sigma (coherence factor) of 0.5-0.9 can be used. As the light source, a light source including any of i-line, h-line, and g-line may be used, or a plurality of these may be used together, or a broad-wavelength light source including all of i-line, h-line, and g-line may be used. .

Incidentally, as the light source of the exposure apparatus to be used, deformed illumination (here, a light source that shields a light component incident perpendicularly to the photomask, including an oblique incident light source such as annular illumination) may be used, but non-deformation illumination The excellent effect of the invention can be obtained by (normal illumination which does not block the vertically incident component).

There is no restriction|limiting in particular in the use of the photomask to which this invention is applied. The photomask of the present invention can be used as a transmissive photomask which can be preferably used in the manufacture of a display device including a liquid crystal display device, an EL display device, or the like. And it is useful as a multi-gradation photomask used for the process of processing the S/D layer and channel of a TFT in one photolithography process.

According to the photomask of the present invention, in the production of high-definition display devices (so-called flat panel displays) including mobile portable terminals, a very important factor such as realization of miniaturization of patterns and securing of margins in the process is achieved. compatible.

As mentioned above, although embodiment of this invention was described concretely, the technical scope of this invention is not limited to the above-mentioned embodiment, Various changes are possible in the range which does not deviate from the summary.

That is, the use, configuration, and manufacturing method of the photomask of the present invention are not limited to those exemplified above, as long as the effects of the present invention are not impaired.

As long as the effects of the present invention are not impaired, an additional optical film or a functional film may be used for the photomask to which the present invention is applied. For example, in order to prevent a problem that the light transmittance of the light-shielding film interferes with inspection or position detection of the photomask, the light-shielding film may be formed in a region other than the transfer pattern. Moreover, you may provide the antireflection layer for reducing reflection of drawing light and exposure light on the surface of a semitransmissive film (rim formation film) or a light shielding film. An antireflection layer may be provided on the back surface of the semitransmissive film (rim forming film).

In addition, for example, in the above, the material which has mutual etching selectivity was used for the rim formation film and the light-shielding film. However, both may use a material that is etched by the same etchant. In that case, as an etching stopper film between the two films, one having etching selectivity with respect to the material of the two films may be interposed. For example, both the light-shielding film and the rim forming film are made of a Cr-based film (Cr has the largest content among the metals it contains), and the etching stopper film is made of a Si-based (Si compound or metal silicide compound is included) film. can

10: light emitter
20: light blocking part
21: complete light-shielding part
22: Rimbu
30: translucent part
50: photomask blank
51: transparent substrate
52: rim forming film
53: light shield
54: first photoresist film
55: resist pattern

Claims (8)

A photomask for manufacturing a display device having a transfer pattern comprising a light-transmitting portion, a light-shielding portion and a semi-transmissive portion for forming a resist pattern having a plurality of different residual film values on a transfer object by exposure, the photomask comprising:
The light-transmitting part is made by exposing a transparent substrate,
The light blocking unit,
a complete light-shielding portion in which at least a light-shielding film is formed on the transparent substrate;
a rim portion having a width γ formed in contact with an outer edge of the complete light shielding portion and formed with a semi-transmissive rim forming film on the transparent substrate;
The semi-transmissive part is formed by being sandwiched between the rim part from only two opposing directions, and the transparent substrate is exposed with a predetermined width α,
The width α is set such that the transflective portion has an exposure light transmittance that is smaller than the exposure light transmittance of the translucent portion;
The said rim formation film|membrane is 5 to 60 % of transmittance|permeability Tr with respect to the light of the representative wavelength of the exposure light, and the phase shift amount with respect to the light of the said representative wavelength is 90 degrees or less, The photomask. According to claim 1,
The width γ of the rim is 0.1㎛≤γ<1.0㎛, the photomask. 3. The method of claim 1 or 2,
The transfer pattern is a photomask that forms a removal pattern having a pattern width of 1 to 4 µm on an object to be transferred corresponding to the semi-transmissive portion by an exposure apparatus for manufacturing a display device. 3. The method of claim 1 or 2,
The photomask for which the said transfer pattern is for exposure with the broad-wavelength light source within the range of 300-500 nm by the exposure apparatus for display apparatus manufacture. 3. The method of claim 1 or 2,
The transfer pattern is a thin film transistor manufacturing pattern, and the semi-transmissive portion corresponds to a channel portion of the thin film transistor, a photomask. A method of manufacturing a photomask having a transfer pattern comprising a light-transmitting portion, a light-shielding portion and a semi-transmissive portion for forming a resist pattern having a plurality of different residual film values on a transfer object by exposure, the method comprising:
A step of preparing a photomask blank in which the rim forming film and the light-shielding film are laminated in this order on a transparent substrate;
a first patterning step of using a resist pattern formed on the light-shielding film as an etching mask and patterning the light-shielding film using an etchant for a light-shielding film;
a second patterning step of patterning the rim forming film using an etchant for the rim forming film;
a third patterning step of side-etching the light-shielding film using the resist pattern as an etching mask and using an etchant for a light-shielding film;
A peeling process of peeling the resist pattern
A method of manufacturing a photomask for manufacturing the photomask according to claim 1 or 2, which has. A method for manufacturing a display device, comprising the steps of: preparing the photomask according to claim 1 or 2;
A step of transferring the pattern for transfer onto an object to be transferred by exposing the photomask using an exposure apparatus for manufacturing a display device
A method of manufacturing a display device having 8. The method of claim 7,
The method of claim 1 , wherein the display device includes a thin film transistor.

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