CN102692816A - Manufacturing method of optical mask, image transferring method and manufacturing method of display device - Google Patents

Abstract

The present invention provides a method for manufacturing a photomask, a method for transferring a pattern, and a method for manufacturing a display device, which require substantially no additional investment even when a line and space pattern with a fine pitch width is formed on an object to be processed. Pattern formation is performed. The side etching width α is set based on the etching conditions when etching the workpiece. The line width _ML and the space width M _S of the pattern for transfer are determined from the side etching width α, the line width W _L and the space width _WS of the film pattern. And, determine the light transmittance of exposure condition and semi-transmissive film that are applied at the time of exposure, so that through the exposure and etching of the photomask using the transfer pattern with the determined line width M _L and gap width M _S , forming a film pattern of lines and spaces with a line width W _L and a space width _WS on the workpiece.

Description

Photomask manufacturing method, pattern transfer method, and display device manufacturing method

technical field

The present invention relates to a method of manufacturing a photomask, a method of pattern transfer, and a method of manufacturing a display device, which are used in the manufacture of flat panel displays (FPD: hereinafter referred to as "FPD"), etc., such as liquid crystal display devices.

Background technique

At present, there are VA (Vertical Alignment: vertical alignment) method and IPS (In Plane Switching: in-plane switching) method as methods used in liquid crystal display devices. By applying these methods, it is possible to provide an excellent dynamic image with fast liquid crystal response and a sufficiently large viewing angle. In addition, by using a line and space pattern based on a transparent conductive film, that is, a line and space pattern, in the pixel electrode portion of a liquid crystal display device to which these methods are applied, it is possible to achieve a response speed and a field of view. Corner improvement.

In recent years, in order to further improve the response speed and viewing angle of liquid crystals, there is a demand for pixel electrodes with finer line widths (CD (Critical Dimension: Critical Dimension)) of line and space patterns (for example, refer to Patent Document 1).

[Patent Document 1] Japanese Patent Laid-Open No. 2007-206346

In general, a photolithography process is performed for pattern formation of a pixel portion or the like of a liquid crystal display device. The photolithography process is as follows: use a photomask to transfer a predetermined pattern to a resist film formed on a workpiece to be etched, develop the resist film to form a resist pattern, and then use the resist film to form a resist pattern. The pattern is used as a mask to etch the object to be processed.

For example, among the above-mentioned liquid crystal display devices, a liquid crystal display device (comb-shaped pixel electrodes, etc.) in which a line-and-space pattern is formed on a transparent conductive film may be used, and as a photomask for forming the liquid crystal display device, a The so-called binary mask. The binary mask is a two-level photomask composed of a light-shielding portion (black) that blocks light and a light-transmitting portion (white) that transmits light by patterning a light-shielding film formed on a transparent substrate. In the case of forming a line and space pattern using a binary mask, a binary mask is used in which a line pattern (line pattern) formed on a transparent substrate is formed using a light-shielding portion, and a space pattern (space pattern) is formed using a light-transmitting portion. pattern).

However, there is a need to form such a line-and-space pattern with a finer pitch width than conventional ones. For example, in a VA-type liquid crystal display device, when the pitch width of pixel electrodes made of a transparent conductive film is miniaturized, the transmittance in the liquid crystal display device can be improved, and the illuminance of the backlight can be reduced to obtain a bright image. advantages, and the advantage of being able to improve the contrast of an image. In addition, since the pitch width is the total of the line width and the space width, when the pitch width is miniaturized, the line and/or space width is miniaturized.

In addition to the VA method, for example, the IPS method is expected to be able to form a finer line-and-space pattern. Furthermore, in addition to the above-mentioned applications, there is a need to use finer line and space patterns than conventional ones for wiring patterns of display devices and the like.

However, in order to reduce the pitch width of the line-space patterns formed on the photomask, there are the following problems. When the resist film formed on the object to be processed is irradiated with the transmitted light of the photomask through the line-and-space pattern of the photomask, when the pitch width becomes smaller, the gap width of light transmission becomes correspondingly smaller. It is small, and the influence of the diffraction of light becomes remarkable. As a result, the bright and dark amplitude of the light intensity of the transmitted light irradiated on the resist film becomes smaller, and the total amount of transmitted light irradiated on the resist film also decreases. In the case of forming a resist film with a positive photoresist, a reaction occurs due to light irradiation, thereby improving the solubility of the resist film. Although this part can be removed by a developing solution, it is irradiated to A reduction in the amount of light at the portion to be removed means that a desired pattern width cannot be obtained.

In addition, in dimension design of the line-and-space pattern formed as the transfer pattern of the photomask, it is necessary to consider the width of side etching (described later). That is, when etching an object to be processed, it is necessary to consider the reduction in the size of the line portion due to side etching, and add a size corresponding to the reduced portion to the line pattern of the photomask in advance (in this application, the This additional portion is referred to as "side etching width", which will be described in detail later). Especially in the case of applying wet etching, this dimensional change portion cannot be ignored.

In addition, even if the pitch width becomes smaller, the additional dimension is the same. Therefore, as the line-and-space pattern becomes finer and the pitch width decreases, the opening area of the transfer pattern decreases. That is, the ratio (M _S /M _L ) of the gap width M _S to the line width _ML of the transfer pattern described later becomes small.

For this reason, when exposure is performed using a photomask having a fine line-and-space pattern, the light quantity of transmitted light reaching the object to be processed decreases, and the light intensity distribution is flattened. Furthermore, even if the resist film is developed, a resist pattern serving as a mask for etching the object to be processed cannot be formed. In other words, sufficient resolution cannot be obtained due to the decrease in pitch width of the line-and-space pattern.

This point will be described using FIGS. 1 to 3 .

FIG. 1 is an enlarged plan view illustrating a transfer pattern 102p' included in a photomask 100'. The transfer pattern 102p' is formed by patterning an optical film such as a light-shielding film or a light-semitransmitting film formed on the transparent substrate 101'. FIG. 2 is a schematic diagram showing one step of the manufacturing process of the display device using the photomask 100 ′ illustrated in FIG. 1 . In FIG. 2 , (a) shows a state where exposure light is irradiated to the resist film 203 through a photomask 100 ′, and (b) shows a resist film 203 formed by developing the exposed resist film 203 . The state of the resist pattern 203p, (c) shows that the object to be processed (thin film to be patterned formed on the substrate 201) 202 is wet-etched using the resist pattern 203p as a mask to form the film pattern 202p , (d) shows the state after the resist pattern 203p is peeled off. In addition, FIG. 3( a ) is a schematic diagram showing a state where resist removal failure occurs with the miniaturization of the pitch width P of the transfer pattern 102p' illustrated in FIG. It is a schematic diagram of a state in which the irradiation light amount of the exposure light irradiated on the resist film decreases with the miniaturization of the pitch of the transfer pattern illustrated in FIG. 1 .

In FIG. 1 , an enlarged plan view of a line-and-space pattern having a pitch width P of 8 μm formed as a transfer pattern 102 p ′ is illustrated. Here, the side etching width α was set to 0.8 μm. That is, when the object to be processed 202 is wet-etched from FIG. The side etching was performed, and the resulting dimensional change was set to 0.8 μm (0.4 μm on each side). That is, adding 0.8 μm of line width reduction (assumed) in the etching process, 0.8 μm (0.4 μm on each side) is added to the line width of the resist pattern in advance. The amount of the side etching width α varies depending on the applied etching conditions, but if the etching conditions are fixed, the side etching width α is hardly affected by the pitch width P of the transfer pattern 102p′.

Using the photomask 100' having the transfer pattern 102p' illustrated in FIG. a)) and evaluated the cross-sectional shape of the resist pattern 203p ( FIG. 2( b )) obtained at the time of development. FIG. 3 shows a cross-sectional shape of a resist pattern 203p formed by simulation. As simulation conditions, the optical density of the light-shielding film constituting the transfer pattern 102p' is 3.0 or more, the numerical aperture NA of the optical system of the exposure device is 0.08, and the σ of the optical system (NA of the illumination optical system and NA of the projection optical system ratio) is 0.8, the exposure wavelength intensity ratio of g-line/h-line/i-line is 1:1:1, the material of substrate 201 is SiO ₂ , the material of resist film 203 is positive resist, resist The film thickness of the agent film 203 was 1.5 μm. In addition, a simulation was performed by gradually reducing the pitch width P of the pattern 102p' for transfer from 8 μm to 4 μm every 1 μm. In addition, since the side etching width is set to 0.8 μm, the line width _ML of the transfer pattern 102p′ is P/2+0.8 μm, and the gap width M _S is P/2−0.8 μm.

The conditions for the above simulation are set in consideration of the performance of a standard LCD (Liquid Crystal Display: liquid crystal display) exposure machine. For example, the numerical aperture NA can be set to a range of 0.06 to 0.10, and σ can be set to a range of 0.5 to 1.0. Such an exposure machine generally sets a resolution limit of about 3 μm. In order to cover the exposure machine more widely, numerical aperture NA can be made into the range of 0.06-0.14 or 0.06-0.15. This is because there is also a demand for a high-resolution exposure machine with a numerical aperture NA exceeding 0.08.

In FIG. 3( a ), changes in the shape of the resist pattern 203p when the pitch width P is gradually reduced (from 8 μm to 4 μm in steps of 1 μm) are arranged sequentially from top to bottom. It can be seen that as the pitch width P decreases, the removal amount of the resist film 203 due to the photoreaction of exposure decreases, and the undulation of the resist pattern 203p becomes smooth. In addition, it can be seen that when the pitch width P becomes 6 μm or less, resist removal failure becomes remarkable, and adjacent line portions of the resist pattern 203p are connected to each other. At this time, even if the object 202 to be processed is wet-etched using the resist pattern 203p as a mask, it is difficult to form the film pattern 202p having a desired line-and-space pattern. It is considered as one cause of the largeness that by reducing the pitch width P, the ratio (M _S /M _L ) of the gap width M _S of the transfer pattern 102p' to the line width _ML becomes smaller, thereby transmitting light The irradiation light amount of the exposure light reaching the resist film 203 is insufficient without masking the mask 100 ′.

In FIG. 3( b ), the light intensity distribution of the light transmitted through the photomask exemplifies a state in which the irradiation light amount of the exposure light is insufficient by reducing the pitch width P. FIG. The horizontal axis of FIG. 3( b ) shows the exposure position (μm) on the resist film 203 , and the vertical axis shows the irradiation light amount of the exposure light. As shown in FIG. 3( b ), it can be seen that as the pitch width P gradually decreases from 8.0 μm to 4.0 μm, the irradiation light amount of the exposure light reaching the resist film 203 gradually decreases. In addition, it can be seen that the difference between the portion irradiated with the exposure light (the portion corresponding to the gap portion) and the portion shielded from the exposure light (the portion corresponding to the line portion) becomes smaller. In addition, Bias in FIG. 3( b ) represents the above-mentioned side etching width α.

However, in order to improve the resolution at the time of exposure and form a finer pattern, it is conceivable to apply various methods such as applying a technique conventionally developed for LSI production. For example, it is conceivable to employ measures such as increasing the numerical aperture of the optical system included in the exposure apparatus, shortening the wavelength of exposure light, reducing the wavelength of exposure light to a single wavelength, and using a photomask for phase shift masking. However, in order to adopt these methods, not only a huge investment is required, so that the product price matching with the market expectation cannot be obtained, but also there are technical inconveniences and disadvantages in directly applying to a large-area processed object used in a display device. unreasonable.

In addition, in the transfer of the miniaturized line and space pattern, the above-mentioned decrease in the amount of transmitted light is a problem. On the other hand, for example, it is also conceivable to increase the exposure amount in the photolithography process more than conventionally, thereby increasing The intensity of the transmitted light. However, in order to increase the exposure amount, it is necessary to increase the light source output of the exposure device or to increase the irradiation time, which leads to further equipment investment and increased energy consumption, and is also disadvantageous in terms of lowering production efficiency.

Contents of the invention

The present invention has been made in view of the foregoing, and an object of the present invention is to provide a method for manufacturing a photomask, a method for transferring a pattern, and a method for manufacturing a display device that can form lines and spaces with a fine pitch width on a workpiece. In the case of a pattern, it is also possible to form a pattern without substantially requiring additional investment.

A first aspect of the present invention is a method of manufacturing a photomask,

This photomask has, on a transparent substrate, a pattern for transfer including a line-and-space pattern having a pitch width P having a line portion made of a semitransparent film formed on the transparent substrate and a pattern made of The gap portion formed by exposing the transparent substrate,

The photomask transfers the pattern for transfer on the resist film formed on the object to be processed by exposing using an exposure device and the photomask to form a resist pattern of lines and spaces,

By etching using the resist pattern as a mask, a film pattern of lines and spaces having a line width W _L and a space width _WS is formed on the object to be processed,

In the manufacturing method of this photomask,

determining a side etching width α based on etching conditions when etching the object to be processed,

According to the side etching width α, the line width W _L and the gap width _WS of the film pattern, the line width M _L and the gap width M _S of the transfer pattern are determined,

And, the exposure conditions applied at the time of the exposure and the light transmittance of the light semitransmissive film are determined so that by the exposure using the photomask and the etching, a The film pattern of the lines and spaces of the line width W _L and the space width _WS , and the transfer pattern of the line width M _L and the space width M _S are determined in the photomask.

A second aspect of the present invention is the method for producing a photomask described in the first aspect,

The light transmittance of the light semi-transmissive film is determined according to the determination of the exposure conditions applied during the exposure.

A third aspect of the present invention is the method for producing a photomask described in the first aspect,

Based on the determination of the light transmittance of the semi-transparent film, the exposure conditions applied during the exposure are determined.

A fourth aspect of the present invention is the photomask manufacturing method described in any one of the first to third aspects,

According to the side etching width α, the line width W _L and the gap width _WS of the film pattern, the line width _RL and the gap width _RS of the resist pattern are determined,

The line width _ML and the space width M _S of the transfer pattern are determined based on the line width _{RL and the space width RS of} the resist pattern.

A fifth aspect of the present invention is the photomask manufacturing method described in any one of the first to fourth aspects,

The _{line width RL and the space width RS of the resist pattern are equal to the line width ML and the space width M S of the transfer} pattern, respectively.

A sixth aspect of the present invention is the photomask manufacturing method described in any one of the first to fifth aspects,

The light transmittance of the semi-transparent film is 1-30% with respect to the i-line.

A seventh aspect of the present invention is the photomask manufacturing method described in any one of the first to sixth aspects, wherein

The phase shift amount of the semi-transparent film is 90 degrees or less with respect to the i-line.

An eighth aspect of the present invention is the photomask manufacturing method described in any one of the first to seventh aspects,

The pitch width P satisfies the following formula, and its unit is μm:

P≤2R,

Where R=k×(λ/NA)×1/1000

k: 0.61

λ: median value of the wavelength used for the exposure, in nm

NA: Numerical aperture of the optical system of the exposure apparatus used for the exposure.

A ninth aspect of the present invention is the photomask manufacturing method described in any one of the first to eighth aspects,

The pitch width P is 6 μm or less.

In a tenth aspect of the present invention, in the method for producing a photomask described in any one of the first to ninth aspects, a photomask as follows is produced:

It is assumed that a line and space pattern with a line width M _L1 formed by a light-shielding film and a gap width M _S1 formed by exposing the transparent substrate and a pitch width P ₁ >2R is used on the transparent substrate. Expose the photomask of the photomask to form a resist pattern with a line width equal to M _L1 and a gap width equal to M _S1 on the resist film. When _S ,

In the determination of the exposure conditions applied at the time of said exposure, an effective irradiating light amount _{E E smaller} than the standard irradiating light amount ES is applied,

Where R=k×(λ/NA)×1/1000, the unit of R is μm

k: 0.61

λ: median value of the wavelength used for the exposure, in nm

NA: Numerical aperture of the exposure apparatus used for the exposure.

In an eleventh aspect of the present invention, in the photomask manufacturing method described in any one of the first to tenth aspects,

The manufacturing method of the photomask includes the following steps: patterning the semi-transparent film formed on the transparent substrate by photolithography to form the determined line width M _L and gap width M _S The pattern for transfer.

A twelfth aspect of the present invention is a pattern transfer method, wherein,

Using the photomask produced by the manufacturing method described in claim 11, the effective irradiation light amount E _E is applied by using the irradiation light having a wavelength range from i-line to g-line to the photomask formed on the object to be processed. The transfer pattern is transferred to the resist film.

A thirteenth aspect of the present invention is a pattern transfer method, wherein,

When the exposure device performs the irradiation of the standard irradiation light amount _ES , the irradiation time required when the irradiation area S is irradiated with the maximum illuminance L of the exposure device is the standard irradiation time T _S ,

The irradiation area _S is irradiated with an effective irradiation time _TE shorter than the standard irradiation time _TS by using the exposure device, applying an effective irradiation amount E _E smaller than the standard irradiation amount ES.

A fourteenth aspect of the present invention is a method for transferring a pattern to the resist film formed on the object to be processed using the photomask produced by the manufacturing method described in the tenth aspect. The pattern for transfer printing is described, and in the pattern transfer printing method, the following steps are included:

determining an irradiation time and an illuminance for irradiating light to the photomask using the exposure device based on the determined exposure conditions,

Exposure is performed using the determined irradiation time and illuminance.

A fifteenth aspect of the present invention is a pattern transfer method, wherein,

It is assumed that a line and space pattern with a line width M _L1 formed by a light-shielding film and a gap width M _S1 formed by exposing the transparent substrate and a pitch width P ₁ >2R is used on the transparent substrate. Expose with a photomask to form a resist pattern with a line width equal to M _L1 and a gap width equal to M _S1 on the resist film formed on the object to be processed. The light irradiation amount of the light of the exposure device is When the standard irradiation light intensity E _S ,

A line and space having a line width _ML formed by a semi-transparent film and a gap part having a gap width _Ms formed by exposing the transparent substrate on the transparent substrate, and a pitch width P is used. A patterned photomask is exposed with an effective irradiation light quantity _{E E} smaller than the standard irradiation light quantity E S to form a line width equal to M _L and a space width equal to M _S on the resist film. resist pattern,

Where R=k×(λ/NA)×1/1000, the unit of R is μm

k: 0.61

λ: median value of the wavelength used for the exposure, in nm

NA: Numerical aperture of the exposure apparatus used for the exposure.

A sixteenth aspect of the present invention is the pattern transfer method described in the thirteenth aspect,

The pitch width P is 6 μm or less.

A seventeenth aspect of the present invention is a method of manufacturing a display device using the pattern transfer method described in any one of the twelfth to sixteenth aspects.

According to the method for manufacturing a photomask, the method for pattern transfer, and the method for manufacturing a display device of the present invention, even when forming a line-and-space pattern with a fine pitch width on an object to be processed, it is possible to substantially require no additional investment. Pattern formation is performed.

Description of drawings

FIG. 1 is an enlarged plan view illustrating a pattern for transfer that a photomask has.

FIG. 2 is a schematic view showing one step of the manufacturing process of the display device using the photomask illustrated in FIG. 1 .

3( a ) is a schematic view showing a state where resist removal failure occurs with the miniaturization of the pitch of the transfer pattern illustrated in FIG. A schematic diagram of a state in which the irradiation light amount of the exposure light on the agent film is reduced.

4 is a flowchart showing one step of the manufacturing process of a display device using a photomask according to an embodiment of the present invention.

FIG. 5 is a flow chart showing a manufacturing process of a photomask according to an embodiment of the present invention.

6 is an enlarged plan view illustrating a pattern for transfer of a photomask used in a comparative example.

FIG. 7 is a schematic view showing a comparative example, showing a state where resist removal failure occurs as the pattern becomes finer.

FIG. 8 is a schematic view showing an embodiment of the present invention, showing a state in which poor resist removal is prevented by increasing the amount of irradiation light.

FIG. 9 is a schematic view showing an embodiment of the present invention, showing a state in which poor resist removal is prevented by making the line portion of the transfer pattern translucent.

Label description

100: Photomask

102p: pattern for transfer printing

202: Processed body

202p: Membrane Patterns

203: Resist film

203p: resist pattern

Detailed ways

Based on the above, the following process example will be described: by exposure using a photomask, a transfer pattern is transferred to a positive resist film formed on an object to be processed to form a resist pattern, and By etching using the resist pattern as a mask, a film pattern of lines and spaces having a line width W _L and a space width _WS is formed on the object to be processed.

FIG. 4 is a flowchart showing one step of the manufacturing process of the display device using the photomask 100 according to the present embodiment. In FIG. 4 , (a) shows a state where exposure light is irradiated to the resist film 203 through the photomask 100, and (b) shows a state where the exposed resist film 203 is developed to form a resist film. The state of the resist pattern 203p, (c) shows that the object to be processed (thin film to be patterned formed on the substrate 201) 202 is wet-etched using the resist pattern 203p as a mask to form the film pattern 202p. The state, (d) shows the state after the resist pattern 203p is peeled off.

As long as wet etching is used, the line width of the object to be processed (thin film such as a transparent conductive film to be etched) 202 is affected by side etching, and thus becomes smaller than the line width _RL of the resist pattern. Since this reduction in size must exist, the line width W _L in the film pattern 202p formed by patterning the object 202 is smaller than the line width _RL of the resist pattern 203p. In addition, the gap width _WS in the film pattern 202p _{is larger} than the gap width RS in the resist pattern 203p (see FIG. 4( c )).

Here, when the dimensional change due to the side etching is defined as the side etching width α, it is as follows.

line width W _L of the film pattern 202p < line width R _L of the resist pattern 203p (=W _L +α),

The gap width _WS of the film pattern 202p > the gap width _RS of the resist pattern (= _WS -α).

Therefore, the photomask 100 needs to form a resist pattern 203 p of lines and spaces having a line width _RL and a space width R _S on the resist film 203 .

Therefore, here also in the line-and-space pattern included in the transfer pattern 102p of the photomask 100, the line width M _L and the space width M _S are respectively set to be equal to the line width R _L of the resist pattern 203p. and the gap width R _S are the same (see (a) to (c) of FIG. 4 ).

That is, set to

line width M _L of the transfer pattern 102p = line width R _L of the resist pattern 203p,

Gap width M _S of transfer pattern 102p = gap width R _S of resist pattern 203p.

In addition, the pitch width P is constant in any of the transfer pattern 102p of the photomask 100 , the resist pattern 203p , and the film pattern 202p obtained by processing the object 202 .

Here, it is considered that the pitch width P of the line-and-space pattern of the film pattern 202p to be obtained (that is, the pitch width P of the transfer pattern 102p of the photomask 100 and the pitch width P of the resist pattern 203p) is finely adjusted. change. At this time, even if the line width W _L of the film pattern 202p to be obtained becomes smaller, the size of the side etching width α does not change if the etching conditions are constant. Therefore, when the pitch width P is to be miniaturized, the size of the gap width R _S becomes smaller rapidly than the size of the line width _RL of the resist pattern 203 p decreases. As a result, as the transfer pattern 102p of the photomask 100, it is necessary to form a line-and-space pattern with a very small gap width M _S .

However, even if it is possible to form a line-and-space pattern with a fine gap width _MS (for example, less than 1 μm) as the transfer pattern 102p, it is very difficult to form a resist having the same size as the transfer pattern 102p using the photomask 100. pattern 203p. The reason for this is that the photomask 100 has a small gap width _MS , and the gap width _MS is close to the exposure wavelength (generally i-line to g-line), so the influence of light diffraction caused by the fine slits is significant, Thus, no amount of light sufficient to sensitize the resist film 203 is transmitted.

As a result, when the line-and-space pattern as the film pattern 202p is miniaturized, the transfer pattern 102p formed on the photomask 100 is also miniaturized, so the film pattern 202p using the photomask 100 cannot be formed.

Therefore, the present inventors conducted intensive studies on a photomask manufacturing method, a pattern transfer method, and a display device manufacturing method capable of forming such a line-and-space pattern with such a fine pitch width P on the object 202 to be processed. The following insights were thus obtained.

That is, in pattern transfer using a conventional so-called binary mask as a photomask, of the exposure light reaching the resist, only the pattern for transfer transmitted through the photomask is used. The light in the gap portion of the line and gap pattern. However, when the pitch width P is miniaturized (the pattern is miniaturized) as described above, insufficient light intensity occurs, resulting in poor removal of the resist or the like. The inventors of the present invention have obtained the knowledge that it is effective to provide a certain degree of translucency also to the line portion of the transfer pattern provided on the photomask for such a problem (insufficient light quantity). In addition, it was also found that the amount of irradiation light irradiated by the exposure device is also appropriately controlled, and as a result, the shape of the resist pattern to be formed can be controlled, and fine patterning of the object to be processed can be realized. That is, in FIG. 4 , it is shown that using a semitransparent film pattern for the transfer pattern 102p can solve the above-mentioned problem of insufficient light quantity.

Hereinafter, various aspects of the invention of the present application completed based on the above knowledge will be shown.

(first method)

A first aspect of the present invention is a method of manufacturing a photomask 100,

This photomask 100 has, on a transparent substrate 101, a transfer pattern 102p including a line-and-space pattern having a pitch width P having a line portion made of a semitransparent film formed on the transparent substrate 101. , and the gap portion formed by exposing the transparent substrate 101,

By exposure using the exposure device and the photomask 100, the transfer pattern 102p is transferred to the resist film 203 formed on the object 202 to form a resist pattern 203p of lines and spaces,

And by etching using the resist pattern 203p as a mask, a film pattern 202p of lines and spaces having a line width W _L and a space width _WS is formed on the object 202 to be processed. In the manufacturing method of the photomask 100 middle,

Determine the side etching width α based on the etching conditions when etching the workpiece 202,

According to the side etching width α, the line width W _L and the gap width _WS of the film pattern 202p, the line width _ML and the gap width M _S of the transfer pattern 102p are determined,

And, determine the exposure conditions used in exposure and the light transmittance of the light semitransmissive film, so that the exposure through the photomask 100 using the transfer pattern 102p having the determined line width M _L and gap width M _S , and etching, a film pattern 202p of lines and spaces having a line width W _L and a space width _WS is formed on the object 202 to be processed.

Among the above, wet etching is preferably used for etching. In addition, the lower etching width α is a positive value (α>0).

In addition, the pitch width P is as follows.

Pitch width P = line width W _L of film pattern + gap width W _S

= line width R _L of resist pattern + space width R _S

= Line width M _L of transfer pattern + Gap width M _S

The effect of this embodiment is remarkable when the pitch width P is, for example, 6 μm or less.

(the second method)

After determining the side etching width α, how to set the line width RL and gap width _R of the resist pattern 203p can be determined according to the side etching width α and the line width W _L and gap width _WS of the film pattern to be obtained The value of _S. Then, the exposure conditions for forming the resist pattern 203p having the line width _RL and the space width _RS and the transmittance of the transfer pattern 102p (transmittance of the light semitransmissive film) can be determined.

In the second aspect, the transmittance of the pattern 102p for transfer (the transmittance of the light semitransmissive film) is determined based on determination of exposure conditions. That is, first, a desired exposure condition (irradiation light amount or irradiation time) is determined, and an appropriate transmittance (of the light semi-transmissive film) of the transfer pattern 102p under the condition is determined.

(the third method)

Contrary to the second aspect, exposure conditions can also be determined by determining the transmittance of the transfer pattern 102p (that is, the transmittance of the light semi-transmissive film). That is, it is possible to determine an appropriate transmittance of the pattern 102p for transfer (that is, of the light semitransmissive film) and determine desired exposure conditions (irradiation light amount or irradiation time) under the conditions.

Here, the exposure conditions include the amount of irradiation light. The irradiation light amount is the product of the light source illuminance of the exposure device and the irradiation time. The irradiation time is related to the time required for scanning exposure of the entire irradiation surface. The illuminance that can be irradiated by the exposure device can be determined, and the irradiation time (and the time required for scanning exposure) can be determined based on the illuminance. Alternatively, the illuminance can also be determined according to a desired irradiation time.

(the fourth method)

As described above, the line width RL and the space width R _S of the resist pattern _203p are determined according to the side etching width α, the line width W _L and the space width _WS of the film pattern 202p,

The line width M _L and the space width M _S of the transfer pattern 102p can be determined from the line width R _L and the space width _RS of the resist pattern 203p. In addition, the line width M _L and the space width M _S of the transfer pattern 102p can be directly determined from the side etching width α, the line width W _L and the space width _WS of the film pattern 202p. Hereinafter, the former will be used for description.

FIG. 4 shows a state in which the resist film 203 on the object to be processed 202 is exposed through the photomask 100 of this embodiment.

Here, there is no particular restriction on the value of the pitch width P of the line-and-space pattern. However, the invention of this embodiment can obtain a remarkable effect when processing a fine line-and-space pattern, for example, a particularly remarkable effect can be obtained when the pitch width P is 6 μm or less.

In addition, the line-and-space pattern as the transfer pattern 102p formed on the photomask 100 can be formed by patterning a light semitransmissive film formed on the transparent substrate 101 by photolithography. At this time, a line-and-space pattern composed of line portions obtained by forming a semitransparent film on the transparent substrate 101 and gap portions exposed from the transparent substrate 101 can be used as the transfer pattern 102p (see FIG. a)).

When designing the photomask 100 having such transfer pattern 102p, the light intensity distribution reaching the resist film 203 on the object 202 can be appropriately controlled. Therefore, in the invention of this embodiment, first, the value of the side etching width α based on the etching conditions of the object 202 to be processed is determined. In addition, here, it is preferable to apply a positive resist as a material of the resist film 203 .

Regarding the line width W _L and space width WS in the line-and-space pattern of the object to be processed 203 finally obtained, and the line width R _{S and} space width of the resist pattern 203p used as an etching mask when etching the object 203 R _S relationship, as described below.

As described above, the side etching width α (>0) is each of the line width R _L and space width _RS of the resist pattern 203p and the line width W _L and space width of the film pattern 202p formed on the object 202 to be processed. Dimensional difference in width _WS ,

Therefore, the line width _RL of the resist pattern 203p = the line width W _L of the film pattern 202p + the side etching width α,

Gap width R _S of the resist pattern 203p = gap width W _S of the film pattern 202p - side etching width α (see FIG. 4( d )( e )).

Therefore, the transfer pattern 102p on the photomask 100 for forming the resist pattern 203p having such values of the line width _RL and the space width _RS is determined.

(the fifth mode)

Preferably, the line width R _L and the space width R _S of the resist pattern 203p are equal to the line width M _L and the space width M _S of the transfer pattern 102p, respectively.

That is, it is preferable to form a line-and-space pattern having the same line width M _L and space width M _S as the line-and-space pattern of the transfer pattern 102p included in the photomask 100 as the resist pattern 203p. By setting in this way, it is easy to control the line width accuracy of the resist pattern 203p most stably.

And, determine the light transmittance of exposure condition and semi-transmissive film that are applied when exposing, so that can utilize the photomask 100 of the transfer pattern 102p that has determined line width M _L and space width M _S , form the photomask 100 that has The resist pattern 203p has a line width _RL and a space width _RS . This is based on the inventor's knowledge that, depending on the exposure conditions applied at the time of exposure, even if the values of the line width M _L and the space width M _S of the transfer pattern 102p are constant, the line width R _L of the resist pattern 203p and the value of the gap width _RS will also change. That is, when the exposure conditions change, the intensity distribution of light transmitted through the fine line-and-space pattern changes, and the change in the light intensity distribution changes the shape of the resist pattern 203p formed on the object 202 to be processed. In addition, the light transmittance of the semi-transparent film also affects the light intensity distribution. Therefore, in order to obtain the desired line width _RL and space width R _S , the exposure conditions to be applied and the light transmittance of the light semitransmissive film are found.

In the above, the exposure conditions include the amount of irradiation light when the photomask 100 is irradiated with light from the exposure apparatus. For example, when the amount of irradiated light is changed, a curve of light transmission intensity transmitted through the photomask 100 having the pattern 102p for transfer can be obtained by simulation, and the desired resist pattern (for example, M _L =R _L , M _S =the amount of irradiation light of the resist pattern like R _S ) 203p.

Therefore, for example, as shown in the second mode, when the light transmittance of the light semitransmissive film used for the transfer pattern 102p of the photomask 100 is determined, and the transfer pattern 102p based on this semitransparent film is used , the appropriate exposure conditions can be determined by the above simulation.

Alternatively, for example, as shown in the third aspect, after the exposure conditions are determined, the light semi-transmissive film of what kind of light transmittance is used may be obtained by the above-mentioned simulation based on the exposure conditions.

Alternatively, instead of the above-mentioned simulation, the line width _RL and the gap width _RS obtained when the light transmittance and exposure conditions of the semi-transparent film are respectively changed are respectively obtained, and their correlation is grasped, and used to obtain Conditions for desired line width W _L and space width _WS .

Here, the irradiation light amount is the product of the illuminance possessed by the exposure apparatus and the irradiation time. Therefore, in order to obtain a predetermined amount of irradiation light in the step of determining the exposure conditions, the irradiation time can be determined based on the illuminance of a predetermined light source included in the exposure apparatus. Alternatively, a desired irradiation time may be determined, and an illuminance sufficient for the required irradiation light amount within the irradiation time may be determined.

For example, if the illuminance of the exposure device to be used is increased to set, and the set irradiation time is shortened compared to the past, the production efficiency of the final product (such as a liquid crystal display device) can be improved, thereby becoming an advantage in mass production. Great advantage.

As can be understood from the above, if the transfer pattern 102p is determined, the amount of irradiation light required to expose the resist film 203 can depend on the exposure conditions (illuminance and irradiation time) and the light intensity used in the transfer pattern 102p. The combination of the transmittance of the semi-transparent film is determined. Therefore, optimum production conditions can be obtained by appropriately selecting these three by the manufacturer of the display device. This brings a significant advantage over production using conventional binary masks.

Here, according to the study of the inventors, the light transmittance of the light semitransmissive film is preferably 1 to 30% with respect to the irradiation light of the exposure device. Here, the light transmittance of the light semi-transmissive film refers to the light transmittance of the line portion of the pattern 102p for transfer, but as described above, the light transmittance of a part of the pattern 102p for transfer will be affected by the light at the edge of the pattern. Diffraction or the like of the film varies, so the film transmittance (light transmittance in an area sufficiently large for the resolution limit under exposure conditions) of the light semitransmissive film to be used is set here.

(the sixth method)

In the invention of the present embodiment, it is preferable to expose the resist film 203 using irradiation light that includes i-line to g-line in the wavelength range. When the representative wavelength is the i-line, the light transmittance of the semi-transparent film is preferably 1 to 30% for the i-line. When this range is exceeded, the side surface of the resist pattern to be formed is inclined, and it may become difficult to control the line width when etching an object to be processed using this as an etching mask. More preferably, it is 1 to 20%, More preferably, it is 2 to 10%.

In addition, it is preferable that the phase difference between the exposure light transmitted through the transparent substrate 101 and the exposure light transmitted through the transparent substrate 101 and the semi-transparent film is 90 degrees or less. In other words, the phase shift amount of the exposure light of the light semitransmissive film is preferably 90 degrees or less. For example, when the representative wavelength of exposure light is i-line, the above-mentioned phase difference of the light semitransmissive film with respect to i-line is preferably 90 degrees or less. More preferably, it is 60 degrees or less.

This is because, according to the research of the inventors, when the above-mentioned phase difference of the semitransparent film used for transferring the pattern is close to 180 degrees, the shape of the resist pattern 203p formed on the object 202 will not be optimized, On the contrary, the phase shift effect by the light semitransmissive film may reduce the advantage of increasing the light reaching the resist film.

(the seventh mode)

This embodiment is particularly advantageous when forming a pattern finer than before. That is, it is particularly advantageous when the pitch width P is not more than twice the minimum resolution dimension R (μm)=k×(λ(nm)/NA)×(1/1000) defined by Rayleigh's formula. Here, it is set to 2 times because the space width is the total of the line width and the space width.

That is, the pitch width P satisfies

When P≤2R,

The effect of the present invention becomes greater.

Among them, in the above,

k: 0.61 (according to Rayleigh's resolution limit)

λ: wavelength for exposure (nm)

NA: Numerical aperture of the optical system of the exposure apparatus used for exposure.

(the eighth mode)

In addition, the effect of the invention is remarkable when the pitch width P (μm) is 6 (μm) or less. For example, the effect of the present invention is particularly remarkable when the line width W _L or the space width _WS of the film pattern 202p is smaller than 3 μm. That is, considering that the wavelength range of a generally used exposure device is 365-436nm (median value 400nm), and the NA of the optical system is 0.08, a remarkable effect can be obtained when a fine pattern with a pitch width P≤6μm is to be realized. Furthermore, when it is desired to realize a fine pattern with a pitch width P≦5 μm, a more remarkable effect can be obtained.

(the ninth mode)

In the conventional method of forming a line-and-space pattern on the workpiece 202 using a so-called binary mask, there is no problem in resolution when the pitch width P of the line-space pattern is large. On the other hand, according to the present embodiment, compared with the conventional method of forming a line-and-space pattern on the object 202 using a binary mask, the intensity of light reaching the resist film 203 can be increased, and the intensity of light reaching the resist film 203 can be appropriately selected. The control of the light intensity distribution is performed based on both conditions of the exposure conditions and the transmittance of the light semi-transmissive film, so it is possible to manufacture a photomask with higher productivity than conventional ones.

That is, it is assumed that a line having a line width M _L1 formed by a light-shielding film and a gap portion of a gap width M _S1 formed by exposing the transparent substrate 101 is used on the transparent substrate 101, and a line having a pitch width P ₁ >2R is used. The amount of light irradiated by the exposure device when a resist pattern 203p of a line-and-space pattern having a line width equal to M _L1 and a space width equal to M _S1 is formed on the resist film 203 is When the standard irradiation light intensity E _S ,

In determining the exposure conditions applied at the time of exposure, the photomask can be designed by applying the effective irradiation light amount E _E smaller than the standard irradiation light amount _ES . Photomasks can be fabricated using this design.

Where R(μm)=k×(λ/NA)×1/1000

k: 0.61

λ: median value of the wavelength used for the exposure (nm)

NA: Numerical aperture of the exposure apparatus used for the exposure.

Conventionally, in the line-and-space pattern whose pitch width P exceeds twice the resolution limit R, the problem of poor resolution due to the insufficient amount of transmitted light from the photomask described above hardly becomes a problem. The inventors of the present invention studied a photomask 100 capable of forming a resist pattern 203 p having a shape sufficient as an etching mask even in a finer line-and-space pattern. Furthermore, as a solution to this problem, selection of the light transmittance of the light semitransmissive film used for the transfer pattern 102p of the photomask 100 and the exposure conditions at the time of exposing the photomask 100 was found. In the present form, this means is further developed, and a method is proposed in which the amount of irradiation light is further reduced than before and a fine pattern transfer is performed.

Here, the light-shielding film refers to a film having an optical density OD of 3.0 or more. It is the same as the light-shielding film used in conventional so-called binary masks.

In addition, a photomask having a line-and-space pattern (line width M _L1 , space width M _S1 ) having a pitch width P ₁ >2R means that the pitch width (line width + gap width) is the resolution limit obtained from Rayleigh's formula The photomask for transferring the pattern is more than 2 times larger, and the photomask is used to form such a line and space pattern on the object 202 to be processed. The pitch width _P1 is greater than 2R in Rayleigh's formula above. Preferably, the pitch width _P1 can be set to be 8 μm or more and about 10 μm. In addition, it is preferable that the line width M _L1 and the gap width M _S1 are larger than the resolution limit R in the above-mentioned Rayleigh's formula (M _L1 >R, M _S1 >R).

For example, both the line width _ML1 and the space width M _S1 are preferably not less than 3 μm and not more than 6 μm.

A photomask having such a line-and-space pattern can be used to expose the resist film 202 to obtain a resist pattern of a line-and-space pattern with a line width R _L1 equal to M _L1 and a space width R _S1 equal to M _S1 203p. When the irradiated light amount at this time is set as the standard irradiated amount _ES , according to the present embodiment, the resist pattern 203p of a desired line and space pattern can be obtained with the standard irradiated amount E _E smaller than the standard irradiated amount _ES .

In addition, in the above, the conditions of the optical system used for an exposure apparatus, the resist development conditions for forming the resist pattern 203p, etc. were made constant. In addition, it is also possible to make the wavelength range of irradiation light the same.

That is, by making the film forming the pattern of the photomask translucent, it is possible to change the required irradiation amount of the exposure device.

(the tenth mode)

The photomask 100 can be manufactured by performing a photolithography process after performing the above-mentioned photomask design process for setting the line width M _L , the gap width M _S , and the transmittance of the transfer pattern 102p. FIG. 5 is a flowchart showing the manufacturing process of the photomask 100 of this embodiment.

First, a photomask blank 100 b in which a light semitransmissive film 102 and a resist film 103 are sequentially laminated on a transparent substrate 101 is prepared. Then, the blank 100b for a photomask is drawn by a laser drawing machine etc., and the resist film 103 is partially exposed to light (FIG.5(a)). Next, a developing solution is supplied to the resist film 103 to perform development, and a resist pattern 103p covering the line portion of the transfer pattern 102p to be formed is formed ( FIG. 5( b )). Next, using the formed resist pattern 103p as a mask, the optical film 102 is etched to form a transfer pattern 102p ( FIG. 5( c )). Then, the resist pattern 103p is removed, and the manufacture of the photomask 100 of this embodiment is completed (FIG.5(d)).

In addition, the transparent substrate 101 is made of, for example, quartz (SiO ₂ ) glass, or includes SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ , RO (R is an alkaline earth metal), R ₂ O (R ₂ is an alkali metal) Flat plates made of low-expansion glass, etc. The main surfaces (front and back) of the transparent substrate 101 are polished or the like to be flat and smooth. The transparent substrate 101 can be, for example, a square shape with a side of about 500 mm to 1300 mm. The thickness of the transparent substrate 101 can be, for example, about 3 mm to 13 mm.

In addition, the semi-transmissive film 102 can use a material containing chromium (Cr), such as chromium compounds such as chromium nitride (CrN), chromium oxide (CrO), chromium oxynitride (CrON), chromium fluoride (CrF), etc., or Metal silicides (MoSix, MoSiO, MoSiN, MoSiON, TaSix, etc.) are formed.

In addition, the resist film 103 can be formed using a positive photoresist. In this case, for example, a method such as a slit coater or a spin coater can be used.

(the eleventh mode)

A pattern transfer method can be carried out by using the photomask 100 produced by the manufacturing method described in any one of the first to tenth aspects, using the irradiation light having the wavelength range of the i-line to the g-line, and applying effective irradiation The amount of light E _E transfers the transfer pattern 102p to the resist film 203 formed on the object 202 to be processed.

(the twelfth mode)

The following pattern transfer method can be implemented: when the exposure device performs the irradiation of the standard irradiation light amount _ES , the irradiation time required when the irradiation area S is irradiated with the maximum illuminance L of the exposure device is the standard irradiation time T _S ,

The irradiation area S is irradiated by using an exposure device, applying an effective irradiation amount E _E smaller than a standard irradiation amount _ES , and using an effective irradiation time T _E smaller than a standard irradiation time T _S .

(the 13th mode)

A pattern transfer method in which a transfer pattern 102p is transferred to a resist film 203 formed on a workpiece 202 on the photomask 100 produced by the manufacturing method described in the tenth aspect can be implemented. The transfer method includes the steps of determining the irradiation time and illuminance for irradiating light to the photomask 100 using an exposure device based on the determined exposure conditions, and performing exposure using the determined irradiation time and illuminance.

(the 14th mode)

It is possible to implement a pattern transfer method using a line portion including a line width _ML1 formed by a light-shielding film and a gap portion having a gap width M _S1 formed by exposing the transparent substrate 101 on the transparent substrate 101, and the pitch width The photomask of the line-and-space pattern with P ₁ >2R is exposed, and the resist film of the line-and-space pattern with the line width equal to M _L1 and the space width equal to M _S1 is formed on the resist film 203 formed on the object 202 to be processed. When the amount of light irradiated by the exposure device at the time of the etch pattern is the standard irradiated light amount _ES ,

Using the transparent substrate 101 has the line portion including the line width _ML formed by the semi-transparent film and the gap portion formed by the transparent substrate 101 exposed to the gap width M _S , and the line and gap pattern of the pitch width P The photomask 100 is exposed with an effective irradiation light quantity _{E E smaller} than the standard irradiation light quantity ES, and a resist of a line-and-space pattern having a line width equal to M _L and a space width equal to M _S is formed on the resist film 203. pattern.

Where R(μm)=k×(λ/NA)×1/1000

k: 0.61

λ: median value of the wavelength used for the exposure (nm)

NA: Numerical aperture of the exposure apparatus used for the exposure.

(the 15th mode)

In the pattern transfer method of the twelfth aspect, the pitch width P can be set to 6 μm or less. That is, considering that the wavelength range of a generally used exposure device is 365-436nm (median value 400nm), and the NA of the optical system is 0.08, a remarkable effect can be obtained when a fine pattern with a pitch width P≤6μm is to be realized. Furthermore, when it is desired to realize a fine pattern with a pitch width P≦5 μm, a more remarkable effect can be obtained.

(the 16th mode)

A display device can be manufactured by the pattern transfer method described in any one of the eleventh to fifteenth aspects.

Conventionally, when forming a line-and-space pattern on the object 202 to be processed, a photomask including a line-and-space pattern having a light-shielding portion and a light-transmitting portion as a pattern for transfer has been used. At this time, there is no variable such as the transmittance of the line portion, and the design is performed considering the transmittance to be substantially zero.

However, in this embodiment, the transmittance of this portion is not set to zero but is set to be a variable within a predetermined range, thereby greatly increasing the degree of freedom of the designable line and space pattern. Furthermore, by setting the transmittance of the pattern as a variable, it is possible to freely select the exposure conditions (illuminance, irradiation time) of the exposure device which is another element determining the light intensity distribution curve of the transmitted light of the photomask 100 . That is, in order to realize the shape of the desired line-and-space pattern on the object 202 to be processed, when determining the light intensity distribution for exposing the resist film 203, the lines passing through the transfer pattern 102p included in the photomask 100 can be The combination of the transmittance of the part and the exposure conditions of the exposure device is selected to select the optimal condition.

In addition, the various methods described in the above-mentioned first to sixteenth aspects can preferably be used in the case of manufacturing a pixel electrode of a display device. This pixel electrode can be obtained by patterning a transparent conductive film made of ITO or IZO.

【Example】

The object to be processed (here, ITO transparent conductive film) is wet-etched, and the line and space patterns are processed to form lines with a pitch width P = 5 μm (line width W _L = 2.5 μm, gap width W _S = 2.5 μm) Membrane pattern with gaps. According to wet etching conditions, here, the side etching width α was set to 0.5 μm. In addition, the conditions applied in the following simulations are the same as those described in FIGS. 1 to 3 . In addition, in the following description, the standard irradiation amount is normalized to 100 mJ/cm ^<2> about the irradiation light amount of an exposure apparatus.

(comparative example)

First, as a comparative example, the exposure simulation results of a photomask having a line and space pattern formed by patterning a light-shielding film (optical density 3.0 or higher) as a transfer pattern (see FIG. 6 ) are shown (see FIG. 7).

Fig. 7(a) is a pattern for transfer with a pitch width P ₁ =8 μm (M _L1 =4.5 μm, M _S1 =3.5 μm) used in a line and space pattern based on a light-shielding film. The cross-sectional shape of the resist pattern when the target line width (W _L1 = _WS1 =4 μm) is formed. The amount of irradiation light applied at this time was set to E _S =100 mJ/cm ² . In addition, the side etching width α is constant and does not depend on the pitch width P of the pattern, so α=0.5 μm.

In addition, the exposure light used here is i-line - g-line, and the median value of a wavelength is 400 nm. In addition, the NA (numerical aperture) of the exposure device to be used is 0.08, so according to Rayleigh's formula, the value of the resolution limit R is:

R=k×(λ/NA)×(1/1000)=3.05

k: 0.61 (according to Rayleigh's resolution limit).

On the other hand, since the P ₁ mentioned above is 8 μm, it is larger than twice the value of the resolution limit R.

In addition, in order to form a resist pattern of a line and space pattern with high line width accuracy on the object to be processed, set

The line width _RL of the resist pattern = the line width _ML of the photomask, and the gap width R _M of the resist pattern = the gap width M _S of the photomask.

According to FIG. 7( a ), there is shown a resist pattern which may be sufficient to be used as an etch mask. Next, FIGS. 7( b ) to ( d ) show changes in the shape of the resist pattern when the pitch width P is gradually reduced every 1 μm (miniaturization of the line and space pattern). Exposure conditions are constant. As the pattern is miniaturized, the resist pattern shape is flattened, the amplitude becomes small, and the separation in the gap portion is insufficient.

In Fig. 7(d), when the line width _ML = 3.0 (= 2.5 + 0.5) μm and the gap width M _S = 2.0 (= 2.5-0.5) μm, the resist pattern is not fully separated and cannot be used as a line. The state of the etch mask with the gap pattern.

(Example)

Here, in order to make up for the lack of light reaching the resist film, a case where a mask design is performed by controlling the exposure conditions and the light transmittance of the pattern for transfer will be described below.

Here, FIG. 8 shows the cross-sectional shape of the resist pattern when the amount of irradiated light is increased by changing the illuminance or irradiation time of the exposure device. That is, according to the state of FIG. 7( d ), it can be seen that when the irradiation amount is increased and the amount of irradiation light capable of forming a resist pattern with line width R _L =gap width R _S =2.5 μm is simulated, it can be set to 125 mJ/ The condition of cm ² is to set the irradiation light to 1.25 times.

However, in order to make up the amount of light with the existing exposure apparatus (without increasing the illuminance), the irradiation tact time must be increased by 1.25 times, and the production efficiency is greatly reduced.

Next, FIG. 9 shows a resist pattern shape obtained when a light semi-transmissive film is used for the transfer pattern of the photomask. The translucent transfer pattern shown here is set to be the same as the pattern formed by patterning the semitransmissive film formed on the transparent substrate. As a raw material, for example, metal silicide or its compound is used. Formed semi-transparent film.

9( a ) to ( f ) show changes in the shape of the resist pattern when the transmittance of the light semitransmissive film used for the line portion of the transfer pattern is changed in the range of 3% to 20%. In addition, here, all the phase shift amounts of exposure light possessed by the light semitransmissive film were set to 40 degrees.

According to FIG. 9( a), it can be seen that when the transmittance of the semi-transparent film is set to 3%, at the irradiation dose increased by 2.5% relative to the reference irradiation dose _ES , the lines of the resist pattern are partially separated, thereby Can be used as an etch mask. Furthermore, it was found that by combining the light transmittance of the light semitransmissive film and the irradiation conditions of the exposure device, a resist pattern with a good shape can be formed with an irradiation dose (effective irradiation dose E _E ) smaller than the reference irradiation dose _ES .

<Other embodiments of the present invention>

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

For example, the present invention is also suitably applied to a method of manufacturing a photomask having a light-transmitting portion and a light-semi-transmitting portion formed by patterning a semi-transmissive film formed on a transparent substrate. A method for producing a pattern for transfer, that is, a photomask in which a portion with a remaining resist film and a portion without a remaining resist film are formed on a resist film on a transfer target. Specifically, it can be suitably applied to a case where a line-and-space pattern having a pitch width P of 6 μm or less is formed on a workpiece. In the above case, corresponding to the light-transmitting portion, a portion without remaining resist film is formed on the transfer target, and a portion having resist remaining film is formed corresponding to the semi-transparent portion.

In addition, for example, the present invention is not limited to the case where the resist film on the transfer target is formed with a positive resist, but is also applicable to the case where it is formed with a negative resist. However, the resist film is preferably formed using a positive resist.

As described above, the photomask of the present invention is particularly suitably applied to the case of exposing by an exposure apparatus having a wavelength range of i-line to g-line, for example. Moreover, as an exposure apparatus, a projection exposure machine, for example, can be suitably used. However, the photomask of the present invention is not limited to these forms, and can be suitably applied to the case of exposing with an exposure apparatus having another wavelength range.

As described above, the photomask of the present invention is suitably applied to, for example, the formation of a line-and-space pattern for pixel electrodes used in a VA system or an IPS system liquid crystal display device. However, it is also suitable for use in the case of manufacturing a liquid crystal display device of another type or a device other than a display device using photolithography.

In the above embodiment, the values of the specific line width W _L and space width _WS of the line-and-space pattern to be obtained are not limited, but are preferably set to be, for example, 0.8W _L ≤ W _S ≤ 1.2W _L . From the viewpoint of line width control during drawing and design freedom of side etching width α and mask bias β, it is preferable that the dimensions of line width and gap width do not deviate extremely.

From the above, according to the present invention, it is possible to use the exposure light of the i-line to the g-line by using the exposure device for LCD, without reducing the amount of exposure radiation and without reducing the production efficiency, and it is possible to form fine lines that cannot be resolved conventionally on the object to be processed. with gap pattern.

Claims (17)

1. A method for manufacturing a photomask having, on a transparent substrate, a transfer pattern comprising a line-and-space pattern of a pitch width P, the line-and-space pattern being formed on the transparent substrate by The line portion formed by the semi-transparent film and the gap portion formed by exposing the transparent substrate, The photomask transfers the pattern for transfer on the resist film formed on the object to be processed by exposing using an exposure device and the photomask to form a resist pattern of lines and spaces, By etching using the resist pattern as a mask, a film pattern of lines and spaces having a line width W _L and a space width _WS is formed on the object to be processed, In the manufacturing method of this photomask, it is characterized in that, determining a side etching width α based on etching conditions when etching the object to be processed, According to the side etching width α, the line width W _L and the gap width _WS of the film pattern, the line width M _L and the gap width M _S of the transfer pattern are determined, And, the exposure conditions applied at the time of the exposure and the light transmittance of the light semitransmissive film are determined so that by the exposure using the photomask and the etching, a The film pattern of the lines and spaces of the line width W _L and the space width _WS , and the transfer pattern of the line width M _L and the space width M _S are determined in the photomask. 2. The method of manufacturing a photomask according to claim 1, wherein: The light transmittance of the light semi-transmissive film is determined according to the determination of the exposure conditions applied during the exposure. 3. The method of manufacturing a photomask according to claim 1, wherein: Based on the determination of the light transmittance of the semi-transparent film, the exposure conditions applied during the exposure are determined. 4. The method of manufacturing a photomask according to claim 1, wherein: According to the side etching width α, the line width W _L and the gap width _WS of the film pattern, the line width _RL and the gap width _RS of the resist pattern are determined, The line width _ML and the space width M _S of the transfer pattern are determined based on the line width _{RL and the space width RS of} the resist pattern. 5. The method of manufacturing a photomask according to claim 1, wherein: The _{line width RL and the space width RS of the resist pattern are equal to the line width ML and the space width M S of the transfer} pattern, respectively. 6. The method of manufacturing a photomask according to claim 1, wherein: The light transmittance of the semi-transparent film is 1%-30% with respect to the i-line. 7. The method of manufacturing a photomask according to claim 1, wherein: The phase shift amount of the semi-transparent film is 90 degrees or less with respect to the i-line. 8. The method of manufacturing a photomask according to claim 1, wherein: The pitch width P satisfies the following formula, and its unit is μm: P≤2R, Where R=k×(λ/NA)×1/1000 k: 0.61 λ: median value of the wavelength used for the exposure, in nm NA: Numerical aperture of the optical system of the exposure apparatus used for the exposure. 9. The method of manufacturing a photomask according to claim 1, wherein: The pitch width P is 6 μm or less. 10. The method of manufacturing a photomask according to claim 1, wherein: Fabricate a photomask as follows: It is assumed that a line and space pattern with a line width M _L1 formed by a light-shielding film and a gap width M _S1 formed by exposing the transparent substrate and a pitch width P ₁ >2R is used on the transparent substrate. A photomask is used for exposure, and when forming a resist pattern with a line width equal to M _L1 and a gap width equal to M _S1 and a line and space on the resist film, the light irradiation light quantity of the exposure device is the standard light irradiation light quantity E _S hour, In the determination of the exposure conditions applied at the time of said exposure, an effective irradiating light amount _{E E smaller} than the standard irradiating light amount ES is applied, Where R=k×(λ/NA)×1/1000, the unit of R is μm k: 0.61 λ: median value of the wavelength used for the exposure, in nm NA: Numerical aperture of the exposure apparatus used for the exposure. 11. The method of manufacturing a photomask according to claim 9, wherein: The manufacturing method of the photomask includes the following steps: patterning the semi-transparent film formed on the transparent substrate by photolithography to form the determined line width M _L and gap width M _S The pattern for transfer. 12. A pattern transfer method, characterized in that, Using the photomask produced by the manufacturing method described in claim 11, the effective irradiation light amount E _E is applied by using the irradiation light having a wavelength range from i-line to g-line to the photomask formed on the object to be processed. The transfer pattern is transferred to the resist film. 13. The pattern transfer printing method according to claim 12, characterized in that, When the exposure device performs the irradiation of the standard irradiation light amount _ES , the irradiation time required when the irradiation area S is irradiated with the maximum illuminance L of the exposure device is the standard irradiation time T _S , The irradiation area _S is irradiated with an effective irradiation time _TE shorter than the standard irradiation time _TS by using the exposure device, applying an effective irradiation amount E _E smaller than the standard irradiation amount ES. 14. A pattern transfer method for transferring the pattern for transfer to the resist film formed on the object to be processed using a photomask produced by the manufacturing method according to claim 10 , in the pattern transfer printing method, it is characterized in that, comprises the following steps: determining an irradiation time and an illuminance for irradiating light to the photomask using the exposure device based on the determined exposure conditions, Exposure is performed using the determined irradiation time and illuminance. 15. A pattern transfer method, characterized in that, It is assumed that a line and space pattern with a line width M _L1 formed by a light-shielding film and a gap width M _S1 formed by exposing the transparent substrate and a pitch width P ₁ >2R is used on the transparent substrate. Expose with a photomask to form a resist pattern with a line width equal to M _L1 and a gap width equal to M _S1 on the resist film formed on the object to be processed. The light irradiation amount of the light of the exposure device is When the standard irradiation light intensity E _S , A line and space having a line width _ML formed by a semi-transparent film and a gap part having a gap width _Ms formed by exposing the transparent substrate on the transparent substrate, and a pitch width P is used. A patterned photomask is exposed with an effective irradiation light quantity _{E E} smaller than the standard irradiation light quantity E S to form a line width equal to M _L and a space width equal to M _S on the resist film. resist pattern, Where R=k×(λ/NA)×1/1000, the unit of R is μm k: 0.61 λ: median value of the wavelength used for the exposure, in nm NA: Numerical aperture of the exposure apparatus used for the exposure. 16. The pattern transfer printing method according to claim 15, characterized in that, The pitch width P is 6 μm or less. 17. A method of manufacturing a display device, wherein the pattern transfer method described in any one of claims 12 to 16 is used.

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