TW201303384A - Photomask substrate, photomask, photomask substrate set, photomask set, photomask manufacturing method, and pattern transfer method - Google Patents

Abstract

To improve transfer accuracy of a pattern when proximity exposure is carried out. A photomask substrate is for use in producing a photomask by forming a transfer pattern on a main surface of the photomask substrate. The main surface has a pattern region where the transfer pattern is to be formed. The maximum value of variation in height of the pattern region is 8.5 ( μ m) or less.

Description

Photomask substrate, photomask, photomask substrate set, photomask kit, photomask manufacturing method, and pattern transfer method

The present invention relates to a substrate for a photomask, a photomask, a substrate set for a photomask, a mask set, a method of manufacturing a photomask, and a pattern transfer method.

A liquid crystal display device included in a computer, a mobile terminal, or the like has a structure in which a TFT substrate having a TFT (Thin Film Transistor) array formed on a light-transmitting substrate, and a light-transmitting substrate A color filter having an RGB (Red Green Blue) pattern is formed thereon, and a liquid crystal is sealed therebetween. A color filter (hereinafter also referred to as CF, Color Filter) is manufactured by sequentially performing a black matrix which forms a boundary portion of a color on one main surface of a light-transmitting substrate. a step of forming a layer, and forming a color filter layer (hereinafter also referred to as a color layer) such as a red filter layer, a green filter layer, or a blue filter layer on one main surface of the light-transmitting substrate divided by the black matrix layer. A step of. The TFT and the color filter described above can be manufactured by photolithography using a photomask.

On the other hand, when the photomask is set on the exposure machine for pattern transfer, the photomask is slightly deflected by its own weight, and Patent Document 1 describes a support mechanism for an exposure machine for reducing the deflection. .

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. Hei 9-306832

The expectation of performance improvement required for liquid crystal display devices is increasing. In particular, display devices such as mobile terminals that are small in size and require high-definition images are required to exceed the performance of previous products in several respects. Including the sharpness of color (no color turbidity), reaction speed, resolution and so on. Because of this need, the pattern forming of the reticle for manufacturing TFT or CF is more accurate than before.

For example, in the photomask for forming a TFT, in order to increase the reaction speed of the liquid crystal display device, it is necessary to make the line width of the fine size finer when forming a pattern on the photomask, for example, to make the TFT pattern itself fine, or The main TFT is combined with a fine TFT and used. Moreover, although the TFT and the CF are used in an overlapping manner, if the coordinates of the pattern of each of the masks and the positioning at the time of transfer are not extremely finely controlled, a positional shift occurs between the two, thereby generating a liquid crystal. The risk of malfunction.

On the other hand, there is still a problem in the following aspects of the photomask for CF formation. As described above, the black matrix layer is used in combination with the color layer. However, as the pattern on the mask is formed more delicately, if the coordinate shift occurs due to variations or differences in the shape of the pattern surface during transfer, color is generated. Bad conditions such as turbidity.

When a black matrix layer or a color filter layer is formed on a light-transmitting substrate using a photomask, it is most advantageous to apply a proximity (proximity) exposure. The reason for this is that the configuration of the exposure machine does not require a complicated optical system as compared with projection (projection) exposure, so that the device cost is also low, and thus the production efficiency is high. However, if the proximity exposure is applied, it is difficult to perform the correction of the distortion at the time of transfer, and thus the transfer accuracy is liable to deteriorate as compared with the projection exposure.

In the proximity exposure, the transfer target body on which the photoresist film is formed is held facing the pattern of the photomask, and the pattern surface is directed downward, and light is irradiated from the back side of the photomask, thereby transferring the pattern to On the photoresist film. At this time, a specific minute interval (proximity gap) is provided between the photomask and the object to be transferred. Further, the photomask has a transfer pattern formed by performing a specific patterning treatment on the light-shielding film formed on the main surface of the transparent substrate.

In general, when the photomask is placed on the proximity exposure exposure machine, the region on which the transfer pattern is formed on the principal plane on which the transfer pattern is formed is held by the holding member of the exposure machine ( Also known as the outer side of the pattern area. Here, there is a case where the photomask mounted on the exposure machine is deflected by its own weight, and the deflection can be corrected to some extent by the holding mechanism of the exposure machine. For example, in the method of Patent Document 1, it is described that a force of a specific pressure is applied from above the mask to the outside of the support point of the holding member that supports the mask from below.

However, the inventors have found that it is useful to reduce the influence of pattern transfer caused by the deflection of the mask, but if it is only such, it is not sufficient to manufacture a precise display device for the above use. For example, it has been found that, in the case of the above-described proximity exposure, the accuracy of the transfer pattern formed on the transfer target is improved even though the formation accuracy of the transfer pattern of the photomask is sufficiently high and within the reference range. Insufficient, there is a possibility that the operation of the liquid crystal display device is poor, or the color is opaque. As the high definition of the liquid crystal display device advances, the deterioration of the overlay precision of such a pattern gradually becomes unacceptable.

The purpose of the invention of the present application is to form light in the light by proximity exposure. When the transfer pattern on the cover is transferred onto the transfer target, the transfer accuracy of the pattern is improved. In particular, the object is to improve the overlay accuracy of the pattern when a plurality of masks are sequentially used for transfer onto the same transfer target.

According to a first aspect of the present invention, a substrate for a photomask for forming a mask for forming a photomask on a main surface, and a height variation of a pattern region on the main surface is provided. The maximum value ΔZmax is 8.5 (μm) or less.

According to a second aspect of the present invention, there is provided a substrate for a reticle according to the first aspect, wherein each of the measurement points set at equal intervals in the pattern region by a predetermined distance P is opposed to the reference surface. When the height is set to Z, the maximum value ΔZmax of the above-described height variation is the difference between the maximum value and the minimum value of the above Z.

According to a third aspect of the invention, there is provided a substrate for a photomask according to the second aspect, wherein the separation distance P is 5 (mm) ≦ P ≦ 15 (mm).

According to a fourth aspect of the present invention, there is provided a method of manufacturing a reticle, comprising the step of preparing a substrate for a reticle according to any one of the first to third aspects, on a main surface of the reticle substrate An optical film is formed thereon, and the optical film is patterned to form a transfer pattern.

According to a fifth aspect of the present invention, a photomask is provided which is formed with a transfer pattern on a main surface, and a maximum value ΔZmax of a height variation of a pattern region on the main surface is 8.5 (μm) or less.

According to a sixth aspect of the present invention, there is provided a reticle according to the fifth aspect, wherein a height of each of the measurement points set at equal intervals apart by a specific separation distance P in the pattern region is set to a height of the reference surface. In the case of Z, the maximum value ΔZmax of the above-described height variation is the difference between the maximum value and the minimum value of the above Z.

According to a seventh aspect of the invention, there is provided a reticle according to the sixth aspect, wherein said separation distance P is 5 (mm) ≦ P ≦ 15 (mm).

According to an eighth aspect of the present invention, there is provided a reticle according to any one of the fifth to seventh aspects, which is used for proximity exposure.

According to a ninth aspect of the present invention, there is provided a reticle according to any one of the fifth to eighth aspect, wherein the reticle has a color filter manufacturing pattern in the pattern region.

According to a tenth aspect of the present invention, a pattern transfer method is provided, wherein the photomask of any of the fifth to ninth aspects is provided on the exposure machine for the proximity exposure, and the pattern is transferred to the object to be transferred. Printed.

According to an eleventh aspect of the present invention, there is provided a substrate kit for a photomask, comprising: a first photomask formed by forming a transfer pattern transferred onto a transfer target onto a main surface a substrate for a photomask and a transfer pattern for transferring the transfer pattern onto the transfer target by superimposing the transfer pattern on the main surface to form a second light In the case of the second photomask substrate, the height of an arbitrary point M in the pattern region set on the main surface of the first photomask substrate is set to Zm with respect to the reference surface, and is located in the second photomask. The height of the point N at the position corresponding to the point M on the first mask substrate in the pattern region on the main surface of the substrate is Zn with respect to the reference surface, and the difference between the Zm and the Zn is obtained. In Zd, the maximum value ΔZdmax of Zd is 17 (μm) or less in the pattern region.

According to a twelfth aspect of the present invention, a photomask kit includes a first photomask formed on a main surface and having a transfer pattern transferred onto the transfer target, and formed on the main surface. a second mask that is transferred to the transfer pattern on the transfer target in a pattern overlapping with the transfer pattern, and is disposed at any point in the pattern region on the main surface of the first mask The height of M with respect to the reference surface is Zm, and the height of the point N at a position corresponding to the point M on the first mask in the pattern region on the main surface of the second mask is higher than the height of the reference plane When Zn is reported and the difference Zd between Zm and Zn is obtained, the maximum value ΔZdmax of Zd is 17 (μm) or less in the pattern region.

According to a thirteenth aspect of the present invention, there is provided a pattern transfer method using an exposure machine for proximity exposure, The transfer pattern of the first photomask according to the twelfth aspect is transferred onto the same transfer target body in a superimposed manner on the transfer pattern of the second photomask according to the twelfth aspect.

According to the invention of the present application, when the transfer pattern formed on the photomask is transferred onto the transfer target by the proximity exposure, the transfer precision of the pattern can be improved. In particular, when a plurality of masks are sequentially used and transferred onto the same transfer target, the overlap accuracy of the pattern can be improved.

<Embodiment of the Invention>

Hereinafter, an embodiment of the present invention will be described.

(1) Manufacturing steps of color filter

First, a manufacturing procedure of a color filter used in a liquid crystal display device or the like will be described with reference to FIGS. 1 to 3. Fig. 1 is a flow chart showing an outline of a manufacturing procedure of the color filter of the embodiment. Fig. 2(a) is a side view showing a state in which a close exposure is performed in the manufacturing process of the color filter of the embodiment, and Fig. 2(b) is a plan view thereof. Fig. 3(a) is a plan view showing a planar configuration of a photomask according to the embodiment, and Fig. 3(b) is a plan view showing a modification thereof.

As shown in FIG. 1, the color filter 10 for a liquid crystal display device is manufactured by sequentially performing a step of forming a black matrix layer constituting a boundary portion of a color on one main surface of the light-transmitting substrate 11. The step of 12p (Fig. 1 (a) to (e)), and the red filter layer 14p, the green filter layer 15p, and the blue filter are formed on one main surface of the light-transmitting substrate 11 divided by the black matrix layer 12p. Light layer 16p The steps of the color filter layer (Fig. 1 (f) ~ (j)). Hereinafter, each step will be described.

(formation of the black matrix layer)

First, a light-transmitting substrate 11 including a light-transmitting resin or glass is prepared, a light-shielding film 12 is formed on one main surface of the light-transmitting substrate 11, and a photoresist film 13 is formed on the light-shielding film 12. 1(a)).

Then, the first photomask 100 for forming a black matrix, and the light-transmitting substrate 11 on which the light-shielding material film 12 and the photoresist film 13 are formed as a transfer target are disposed in the exposure machine 500 for proximity exposure ( Figure 1 (b), Figure 2).

Further, as shown in the plan view of FIG. 3( a ), the first photomask 100 has a pattern region 133 having a specific patterning of the light shielding film formed on one main surface of the transparent substrate 101. The transfer pattern 112p to be formed (hereinafter, the predetermined region to be formed may be set as the pattern region 133 in addition to the region in which the transfer pattern is formed). The shape of the transfer pattern 112p is formed, for example, in a lattice shape to form a black matrix layer 12p. Further, on one main surface of the transparent substrate 101 of the first photomask 100, there is an exposure machine 500 in the vicinity of each of the opposite sides of the outer periphery of the main surface of the main surface of the transparent substrate 101 on the outer side of the pattern region 133. The abutting surface 103 against which the holding member 503 abuts. A light shielding film may be formed on the abutting surface 103, or one of the main surfaces of the transparent substrate 101 may be exposed.

As shown in FIG. 2(a), the abutting surface 103 is supported by the holding member 503 of the exposure machine 500 from below, whereby the first mask 100 is placed in the exposure machine 500 in a horizontal posture. Further, the transfer pattern 112p included in the first photomask 100 faces the photoresist film 13 formed on the light-transmitting substrate 11, for example, It is arranged with a close gap of 10 μm or more and 300 μm or less.

The first photomask 100 and the light-transmitting substrate 11 on which the light-shielding material film 12 and the photoresist film 13 are formed are disposed in the exposure machine 500 for proximity exposure, and after the alignment is completed, the light source 501 and the illumination system 502 are used. The light is irradiated with ultraviolet light or the like from the back side of the first photomask 100, and the photoresist film 13 is exposed through the transfer pattern 112p to expose one portion of the photoresist film 13 (Fig. 1 (c), Fig. 2 (a)). . For exposure, the source of the i-line to g-line can be used.

Then, the first photomask 100 and the exposed light-transmitting substrate 11 on which the light-shielding material film 12 and the photoresist film 13 are formed are removed from the exposure machine 500. Then, the photoresist film 13 is developed to form a photoresist pattern 13p partially covering the light shielding film (Fig. 1 (d)).

Next, the light-shielding film 12 is etched using the formed photoresist pattern 13p as a mask, and a black matrix layer 12p is formed on one main surface of the light-transmitting substrate 11 (Fig. 1(e)). After the black matrix layer 12p is formed, the photoresist pattern 13p is removed.

(formation of red filter layer)

Then, on one main surface of the light-transmitting substrate 11 on which the black matrix layer 12p is formed, for example, a red photoresist film 14 containing a photosensitive resin material is formed (FIG. 1(f)).

Then, the second photomask 200 for forming a red filter layer and the light-transmitting substrate 11 having the black matrix layer 12p and the red photoresist film 14 as the transfer target are disposed in the proximity exposure. Inside the exposure machine 500 (Fig. 1(g)).

Furthermore, as illustrated in the planar configuration of FIG. 3( a ), a pattern region 233 is formed on one main surface of the transparent substrate 201 of the second mask 200, and the pattern region 233 has a transfer pattern 212p formed by processing a light-shielding film into a specific transfer pattern. Further, the shape of the transfer pattern 212p is formed into a shape for forming the red filter layer 14p, and has a shape different from that of the transfer pattern 112p of the first mask 100. Further, on one main surface of the transparent substrate 201 of the second mask 200, in the region outside the pattern region 233 and in the vicinity of each of the opposite sides of the outer periphery of the transparent substrate 201, there is an exposure machine 500. The abutting surface 203 to which the holding member 503 abuts. On the contact surface 203, a light shielding film may be formed, or one main surface of the transparent substrate 201 may be exposed.

As shown in FIG. 2(a), the contact surface 203 is supported by the holding member 503 of the exposure machine 500 from below, whereby the second mask 200 is placed in the exposure machine 500 in a horizontal posture. Further, the transfer pattern 212p included in the second photomask 200 is opposed to the red photoresist film 14 formed on the light-transmitting substrate 11, and is disposed to be interposed between the adjacent gaps.

The second photomask 200 and the translucent substrate 11 on which the black matrix layer 12p and the red photoresist film 14 are formed are disposed in the exposure machine 500 for proximity exposure, and after the alignment is completed, the light source 501 and the illumination system are used. 502, a light such as ultraviolet light is irradiated from the back side of the second photomask 200, and the red photoresist film 14 is exposed through the transfer pattern 212p, and one portion of the red photoresist film 14 is exposed (FIG. 1(h)).

Then, the second photomask 200 and the light-transmitting substrate 11 of the exposed red photoresist film 14 are removed from the exposure machine 500. Then, the red photoresist film 14 is developed and the excess red photoresist film 14 is removed, and the remaining red photoresist film 14 is baked to be hardened to form a red filter layer 14p (FIG. 1(i)). .

(formation of green filter layer and blue filter layer)

Then, the green filter layer 15p is formed in the same manner as the formation of the red filter layer 14p. The blue filter layer 16p is formed, and the color filter such as the red filter layer 14p, the green filter layer 15p, and the blue filter layer 16p is formed on one main surface of the light-transmitting substrate 11 partitioned by the black matrix layer 12p. Layer step (Fig. 1(j)).

(Formation of ITO (Indium Tin Oxides) electrode)

Although not shown, an ITO film is formed as a transparent electrode so as to cover the upper surface of the color filter layer such as the black matrix layer 12p, the red filter layer 14p, the green filter layer 15p, and the blue filter layer 16p. The manufacture of the color filter 10 is finished.

(2) About the transfer precision of the pattern

As described above, in order to manufacture a color filter, a plurality of exposures are performed by proximity exposure using a mask that forms the black matrix layer 12p, the red filter layer 14p, the green filter layer 15p, and the blue filter layer 16p. However, when the proximity exposure is performed, even if the processing accuracy of the transfer pattern included in each mask is sufficiently high and within the reference range, as a result of the overlap of the transfer patterns, the transfer accuracy is not found. full.

According to an intensive study by the inventors, it has been found that the deterioration of the transfer accuracy is caused by a change in the transfer coordinates caused by a slight height variation of the pattern regions in the respective masks. Further, regarding the deterioration of the transfer precision, it has been found that if the transfer pattern of the plurality of masks is superimposed on the transfer target and is enlarged, the function of the final product may be affected. 4 is a schematic view showing a case where the transfer precision of the pattern is deteriorated when the proximity exposure is continued, and FIG. 4(a) shows an enlarged cross-sectional view of the photomask 100' forming the black matrix layer, and FIG. 4(b) shows a red filter. A cross-sectional enlarged view of the photomask 200' of the optical layer, and Fig. 4(c) shows the transfer pattern on the photoresist films 13, 14. condition. Of course, they may also be photomasks used to form other layers.

As shown in FIG. 4(c), the premise that the exposure light irradiated from the exposure apparatus 500 through the masks 100' and 200' to the photoresist film is incident perpendicularly to one main surface of the mask 100', 200'. However, in reality, it is impossible to completely exclude the case where the incident angle is slightly inclined, and there is a case where the angle is inclined by a specific angle (for example, θ). In reality, the upper limit of θ is about 1 degree. In this case, since the projection is obliquely projected, the position of the pattern transferred onto the resist films 13 and 14 is shifted by a certain amount in the horizontal direction in accordance with the magnitude of the inclination θ of the exposed light. In FIG. 4(c), it is shown that the exposed light is incident with respect to the normal inclination angle θ of one of the main surfaces of the reticle 100', 200', so that the transfer position of the pattern is shifted only by S0 in the horizontal direction. .

Even if the above-described transfer shift occurs, as long as the offset amount S0 is fixed across the entire surfaces of the photoresist films 13, 14, the deterioration of the transfer accuracy is hardly affected. However, according to intensive research by the inventors and the like, it is known that the offset S0 varies locally depending on the flatness of one of the main surfaces of the transparent substrates 101', 201'. Further, it can be seen that as the shift amount S0 fluctuates, partial deterioration of the transfer precision of the pattern occurs. In particular, it has been found that even if the amount of variation in the amount of the offset is within the allowable range of each of the mask blanks, when a plurality of masks are used in sequence to overlap the patterns, the direction of the change in the specific overlapping position is specified. Different from each other (for example, in a reticle, the amount of shift at a specific overlapping position is increased, and the other reticle is changed in such a manner that the offset is small at the position), and there is overlap. The cumulative value of the variation locally exceeds the allowable range of the transfer accuracy.

Fig. 4(a) shows one of the transparent substrates 101' in the transfer pattern 112p' An enlarged cross-sectional view of the reticle 100' having a concave structure of depth Zm on the surface. As shown in FIG. 4(c), when the photomask 100' is used for the near-exposure exposure, the transfer position 112 is formed in the concave structure at the height position (Z position) and the other flat regions are transferred. Compared with the height position (Z position) of the pattern 112p', the maximum (at the M point) is only higher than Zm. As a result, the offset amount S1 of the concave structure portion due to the exposure light tilt angle θ is locally larger than the offset amount S0 of the flat portion (S1>S0).

On the other hand, FIG. 4(b) is an enlarged cross-sectional view showing the second photomask 200' having a convex structure having a high degree of Zn on one main surface of the transparent substrate 201' in the transfer pattern 212p'. As shown in FIG. 4(c), when the second photomask 200' is used for proximity exposure, the height position (Z position) of the transfer pattern 212p' formed on the convex structure and other flat regions are The maximum position (at the N point) of the transfer pattern 212p' is lower than the Zn level at the height position (Z position). As a result, the amount of shift S2 of the convex structure portion due to the light tilt angle θ of the exposure is locally smaller than the shift amount S0 of the flat portion (S2 < S0).

Further, the deterioration of the transfer precision of the above-described pattern is caused by the use of a single close exposure of one mask, but it is known from the inventors' intensive research that a plurality of masks are used in particular. When the same transfer target is subjected to the close exposure, the variation of the offset amount S0 exerts a greater influence, and there is a case where the transfer precision of the pattern is further deteriorated. That is, for example, as shown in FIG. 4(c), when the concave structure existing on the first photomask 100' overlaps with the convex structure existing on the photomask 200' on the vertical axis, the proximity exposure is continued, Therefore, the coordinate positions of the black matrix layer and the red filter layer in the portion of the uneven structure are only locally maximally offset | S1-S2 | (=| -Zm-(+Zn)|‧tanθ). In other words, even in the case where the coordinate of the mask of the transfer pattern is used as a reference, the mask of the photomask set of the transfer pattern is used for processing or screening. Further, it is clear that the flatness of the substrate for the photomask having the possibility of manufacturing the photomask of the photomask set needs to be more strictly evaluated.

After intensive research, the inventors have found that in order to improve the transfer precision of the pattern when performing the proximity exposure, it is effective to control the height variation of one of the main surfaces of the transparent substrate in the pattern region.

According to the embodiment to which the present invention is applied, a substrate for a photomask for forming a mask for forming a photomask on a main surface and a height of a pattern region on the main surface is used. The maximum value of variation ΔZmax is 8.5 (μm) or less.

In other words, the substrate for a mask having a maximum value ΔZmax in the pattern region of the above-mentioned | -Zm-(+Zn)| is 8.5 μm or less. If the value is exceeded, there is a combination of height variations of the pattern regions of the photomasks for overlapping exposure on the same transfer target, so that the coordinate offset generated on the transfer target is out of the allowable range. situation. Furthermore, the allowable range of the coordinate offset referred to herein will be described below.

The substrate for a photomask according to the present embodiment can be obtained by precision polishing of a transparent substrate and further by screening of a substrate. However, if the value of the above-mentioned maximum value is excessively small, the processing capability of the processing apparatus may be exceeded or excessive processing time may be required when the surface of the substrate is processed. Therefore, the maximum value ΔZmax in the pattern region is preferably 1 μm or more.

When the height Z with respect to the reference plane at any point in the pattern region is found, the maximum value ΔZmax of the height variation of the pattern region can be set as the difference between the maximum value and the minimum value.

Further, the arbitrary points can be determined and benchmarked, for example, as follows. In other words, a point which is set at a predetermined interval by a predetermined distance P in the pattern region can be set as an arbitrary point. For example, in the pattern region of the reticle substrate, all the lattice points in the XY direction are separated by a specific distance P (preferably 5 mm or more and 15 mm or less, for example, 10 mm), and the height Z is taken as When measuring a point, the difference between the maximum value and the minimum value can be set to the maximum value ΔZmax.

Here, the height Z can be measured using a flatness measuring machine as described below, and can be obtained using a reference plane defined by the apparatus. Further, when measuring the height Z of each point of the pattern region, it is preferable to perform measurement while the substrate for the mask is made vertical and the influence of bending due to its own weight is substantially eliminated.

The flatness control of the substrate for the photomask has the following advantages.

The miniaturization of the device pattern of the liquid crystal display device is progressing. The expectation of thinning is particularly strong for the black matrix (BM) used in color filters. The previous BM width was considered to be sufficient for about 10 μm, and it has recently been expected to be about 8 μm or 6 μm, and the difficulty of manufacturing technology has further increased.

For example, consider the case where a 6 μm BM is to be formed (Fig. 7(a)). When a color plate is superimposed on the BM, the maximum value of the coordinate offset allowed by one (for example, BM. The same applies hereinafter) is 3 μm (Fig. 7(b)). The reason is that if the boundaries of the color plates (such as red (red) and blue (blue)) exceed the width of BM, it will be generated. Poor conditions such as turbidity. Furthermore, considering the line width error of the color plate itself and the line width error of the BM itself, the coordinate offset of one side must be controlled within (3 μm × 1/2 × 1/2 =) 0.75 μm (Figure 7 ( c)).

However, since the drawing reproducibility of the drawing device is about 0.15 μm, the margin on the mask substrate side is (0.75 - 0.15 =) 0.60 μm. This is the allowable value of the coordinate offset caused by the reticle (Fig. 7(d)).

However, the coordinate offset caused by the reticle substrate is not only caused by the flatness (height variation) of the main surface of the reticle. According to the research by the inventors and the like, there are a plurality of factors, which are significant (as a factor cannot be ignored), and distortion of the transfer pattern caused by the contact of the holding member 503 of the exposure machine 500 with the photomask, Or an element corresponding to the shape of the second main surface (back surface) of the pattern region. Here, the shape of the second main surface is related to the coordinate shift generated when the transfer pattern is drawn, and thus cannot be ignored.

Therefore, in order to assign the allowable coordinate offset to the above-mentioned main three factors (Fig. 7(e)) and satisfy the Cpk (Complex Process Capability Index) 1.3, the height of the pattern region is changed. The allowable offset must be set within 0.15 μm in a separate mask (thus, the offset due to the combination of the two masks is 0.3 μm or less) (S1-S2 in Fig. 4(c)).

As described above, the offset is [ΔZmax‧tan θ], and the upper limit of θ is 1 degree, so ΔZmax‧tan θ ≦ 0.15 (μm), ΔZmax ≦ 8.59 (deg), As the maximum variation ΔZmax of the height variation, the coordinate shift caused by the element can be suppressed to the extent that the performance of the BM is not affected by 8.5 μm or less.

Further, it is more preferable that the maximum value ΔZmax of the height variation of the pattern region is 7.5 (μm) or less. In this case, the coordinate accuracy of the sub-liquid crystal display device in which the black matrix line width is changed to about 5.5 μm is sufficient.

A plurality of measurement points can be set at equal intervals apart from the specific separation distance P in the pattern transfer area of the main surface. The main object of the present embodiment is to suppress the deterioration of the coordinate accuracy at the time of transfer caused by the uneven surface shape in the pattern region, and if the distance between the measurement points is too large, the accuracy of the obtained height variation value is lowered. However, since the transparent glass substrate for the photomask is subjected to the stage of precision polishing to remove the irregularities having a small period, a sufficient height variation profile can be obtained by setting the measurement points at a distance of 5 mm or more. Specifically, the distance between the measurement points can be set to 5 ≦ P ≦ 15 (mm). For example, it is preferable to use a lattice point of a grid of 10 mm width as a measurement point.

(3) Method of manufacturing photomask

Hereinafter, a method of manufacturing the photomask according to the embodiment will be described with reference to Figs. 5 and 6 . Fig. 5 is a flow chart showing the steps of manufacturing the photomask of the embodiment. Fig. 6 is a view showing a case where flatness is measured by incident laser light. In the following description, a case where the first photomask 100 for forming a black matrix is manufactured will be described as an example. However, the second to fourth photomasks for forming a color filter layer may be manufactured. The manufacture of the photomask 100 is performed in the same manner.

(Checking the preparation and flatness of the transparent substrate)

First, a transparent substrate 101 as a mask substrate is prepared (Fig. 5(a)). Further, as shown in FIG. 3(a), the transparent substrate 101 has a rectangular plate shape in plan view, and its size can be set, for example, to a long side L1 of 600 to 1400 mm and a short side L2 of 500 to 1300 mm. The thickness T is about 6 to 13 mm. The transparent substrate 101 may contain, for example, quartz (SiO ₂ ) glass or a low-expansion glass containing SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ , RO, R ₂ O, or the like. On one main surface of the transparent substrate 101, a predetermined region where the transfer pattern 112p is formed is provided. Further, the exposure machine 500 holding member 503 abuts on the outer side of the formation predetermined region of the transfer pattern 112p and is on the opposite sides (the long side L1 in the present embodiment) which constitute the outer periphery of the transparent substrate 101. The abutting surface 103 in the vicinity.

The main surfaces (surface and back surface) of the transparent substrate 101 are polished and are flat and smooth, respectively. As described above, the flatness of one main surface of the transparent substrate 101 is precisely polished so that the maximum value ΔZmax of the height variation of the pattern region is 8.5 (μm) or less. Alternatively, as the transparent substrate 101, the filter is satisfied.

The measurement of the flatness is performed in the following manner. In order to find the maximum value ΔZmax of the height variation, the height Z of each measurement point is measured. When a plurality of measurement points are determined on the main surface, the height Z of each point becomes the distance between each measurement point and the reference surface. Moreover, the in-plane difference of the height Z becomes the said height change. For example, when the distance is measured using a flatness measuring instrument, the reference surface which the measuring instrument has may be used as the reference surface. For example, as shown in FIG. 6, a method of injecting laser light onto one main surface of the support area may be used. an examination. For example, it can be carried out by using a flatness measuring machine FFT-1500 (registered trademark) manufactured by Kuroda Seiko Co., Ltd., or a Japanese Patent Publication No. 2007-46946.

FIG. 8 illustrates a contour of a height variation in a pattern region of the photomask substrate obtained in this manner.

As the measurement point, as described above, the entire width of the measurement point is obtained as a grid point which is spaced apart from the pattern area by a distance of a distance P (preferably 5 mm or more and 15 mm or less, for example, 10 mm). Then, the maximum value ΔZmax of the height variation is obtained. In this case, even if only the photomasks having a ΔZmax of 8.5 μm or less are combined and exposed on the same transfer target, the deterioration of the coordinate accuracy caused by the variation in the height of the pattern region is not substantially a problem. On the other hand, even when it exceeds 8.5 μm, it can be used as a mask set as long as the height of the other masks used in combination is the same. This point will be described below.

(Formation of light-shielding film and photoresist film)

Then, on the main surface of the transparent substrate 101, for example, a light-shielding film 112 containing Cr as a main component is formed (FIG. 5(b)). The light shielding film 112 can be formed, for example, by a method such as sputtering or vacuum evaporation. The thickness of the light shielding film 112 is a thickness sufficient to shield the exposure light of the exposure machine 500, and can be set, for example, to about 90 to 140 nm. Further, on the upper surface of the light shielding film 112, an antireflection layer containing, for example, CrO or the like as a main component is preferably formed. Further, the light shielding film 112 may not be formed on the contact surface 103.

Next, a photoresist film 113 is formed on the light shielding film 112 (Fig. 5(b)). The photoresist film 113 can be made of a positive type resistive material or a negative type resistive material. Composition. In the following description, the photoresist film 113 is set to be formed of a positive photoresist material. The photoresist film 113 can be formed, for example, by a spin coating method or a slit coating method.

(patterning step)

Then, the resist film 113 is subjected to drawing exposure by a laser drawing machine or the like to partially absorb a portion of the resist film 113. Thereafter, the developer is supplied to the photoresist film 113 by a method such as a spray method, and developed to form a photoresist pattern 113p covering a portion of the light shielding film 112 (FIG. 5(c)).

Then, a portion of the light shielding film 112 is etched by using the formed photoresist pattern as a mask. The etching of the light shielding film 112 can be performed by supplying a chromium (chrome) etching solution to the light shielding film 112 by a method such as a spraying method. As a result, a transfer pattern 112p formed by patterning the light shielding film 112 is formed on one main surface of the transparent substrate 101 (FIG. 5(d)). Then, the photoresist pattern 113p is removed, and the manufacture of the first mask 100 is completed (FIG. 5(e)).

Furthermore, the measurement of the flatness described above can also be performed after the mask is formed. The method can be the same as described above.

<Other Embodiments of the Present Invention>

In the above-described embodiment, the case of using the photomask substrate which satisfies the requirement that the maximum value ΔZmax of the height variation is 8.5 (μm) or less has been described. However, the present invention is not limited to the above embodiment, and the substrate set for a photomask described below can be used.

That is, a substrate set for a photomask including a transfer pattern for transferring onto a transfer target onto a main surface to form a first photomask can be used. The first photomask substrate and the second photomask for forming the second photomask by forming a transfer pattern for transferring the transfer pattern onto the transfer target by superimposing the transfer pattern on the main surface In the substrate, the height of an arbitrary point M in the pattern region set on the main surface of the first mask substrate is set to Zm with respect to the reference surface, and is located on the main surface of the second mask substrate. The height of the point N in the pattern region corresponding to the point M on the first mask substrate is Zn with respect to the reference surface, and when the difference Zd between the Zm and the Zn is obtained, the pattern is In the region, the maximum value ΔZdmax of the Zd is 17 (μm) or less.

Thereby, a liquid crystal display device or the like excellent in coordinate accuracy can be manufactured. In other words, even if the substrate for the photomask is not satisfied with the "maximum height variation ΔZmax of 8.5 (μm) or less", when the plurality of mask substrate sets obtain the contour of the height variation, that is, When the reticle substrate in which a plurality of height variations are common is combined to satisfy the criterion that "the maximum value ΔZdmax of the height variation of the package is 17 (μm) or less", the mask can be used for the mask. The substrate is used satisfactorily as a substrate set for a photomask for superimposing a pattern on the same transfer target.

For example, as shown in FIG. 9 , at least one of the substrate for the first photomask 100 ′ and the substrate for the second photomask 200 ′ in which the transfer pattern is to be superimposed and exposed on the same transfer target satisfies “the height variation”. In addition to the case where the maximum value ΔZmax is 8.5 (μm) or less, for example, when both of the pattern surfaces are concave, it is possible to provide "the maximum variation in height" as the substrate set for the masks. The value ΔZdmax is 17 μm or less. This is based on the fact that the allowable offset caused by the height variation of the pattern area is within 0.15 μm of the single reticle (thereby, the offset due to the combination of the two reticle is Within 0.3 μm) (S1-S2 of Figure 4(c)). That is, as long as the flatness profile of the reticle of the group is known, even if the maximum value ΔZmax of the height variation of each reticle exceeds 8.5 μm, it is allowed. Thereby, the required standard of the flatness of the single substrate for the photomask can be alleviated, and the production cost of the photomask can be reduced without deteriorating the coordinate accuracy.

In the above description, the same transfer system refers to a film to be patterned in a layer, or a layer which is laminated during the patterning process, and the position of the transfer pattern of each mask is aligned. The object to be transferred in the same order. For example, a mask for a black matrix or a color plate may be sequentially superposed and transferred onto a transfer target to thereby produce a color filter, or a thin film transistor may be superposed thereon to be transferred to the photomask. A liquid crystal display device is thereby fabricated on the transferred body. Further, the transfer target body also includes a state in which a photoresist film to be patterned as a mask is applied.

The maximum value ΔZdmax of the difference between the height of the substrate for the first photomask 100' and the substrate for the second photomask 200' constituting the mask set for the photomask (Zd=|-Zm-(-Zn)|) The method can be the same as described above.

That is, a plurality of measurement points M1, M2, M3, . . . are set on the substrate for the first photomask 100'. The measurement points M1... are plurally arranged at equal intervals in the pattern area on the substrate for the first mask 100'. For example, it is possible to set a lattice point when the lattice is drawn in the XY direction at a specific interval (for example, 10 mm) in the pattern region. Moreover, regarding M1, M2, M3, ..., relative to the base The height of the quasi-surface Zm1, Zm2, Zm3.... On the other hand, in the substrate for the second photomask 200', similarly, when the lattice points N1, N2, N3, ... are set at positions corresponding to the substrate for the first photomask 100', The heights of the reference planes are Zn1, Zn2, Zn3, .... Then, the maximum value ΔZdmax can be obtained from the difference (Zd=| -Zm-(-Zn)|) of the heights of the two substrates located at the corresponding positions.

Moreover, the same evaluation as described above can be performed in the photomask group which is formed by forming the transfer pattern on the substrates for the masks, respectively. Therefore, in the present invention, the photomask set as described below can be used in the same manner as in the present embodiment.

That is, a photomask kit including a first photomask having a transfer pattern transferred onto the transfer target on the main surface, and a transfer surface formed on the main surface and the transfer surface may be used. The second mask that is transferred to the transfer pattern on the transfer target is superposed on the pattern, and the arbitrary point M in the pattern region set on the main surface of the first mask is relative to the reference surface. The height is set to Zm, and the height of the point N at a position corresponding to the point M on the first mask in the pattern region on the main surface of the second mask is set to Zn with respect to the reference surface. When the difference Zd between the above Zm and the above Zn is obtained, the maximum value ΔZdmax of Zd is 17 (μm) or less in the pattern region.

Further, in the above-described mask cover and the photomask kit, the ΔZdmax is preferably 15 (μm) or less.

Furthermore, in the present embodiment, the use of the reticle sets can be performed. Transfer method. In other words, the transfer pattern of the first photomask is transferred onto the same transfer target by superimposing the transfer pattern included in the first photomask with the exposure machine for the proximity exposure. Thereby, an electronic device such as a liquid crystal display device having excellent coordinate accuracy can be obtained.

<Other Embodiments of the Present Invention>

The embodiment of the present invention has been specifically described above, but the present invention is not limited to the embodiment described above, and various modifications can be made without departing from the spirit and scope of the invention.

For example, the black matrix layer 12p is not limited to a case where a metal material such as Cr is used as a main component, and may be formed of a light-shielding photosensitive resin or the like. In the case of using a photosensitive resin, the black matrix layer 12p can be formed by sequentially performing exposure, development, and baking as in the case of a color filter layer.

Furthermore, in the above-described embodiment, a case has been described in which a transparent glass substrate produced by polishing quartz or the like is used as a substrate for a photomask, but the present invention is not limited to this embodiment. For example, as a substrate for a photomask, a photomask substrate in which an optical film or a photoresist film is formed on the transparent glass substrate, or a step of forming a specific transfer pattern on the photomask is used. The present invention can also be preferably applied in the case of a mask intermediate or the like.

According to the present invention, the transfer performance of each of the photomask substrates used for the overlap transfer can be evaluated from the stage of the transparent substrate before the transfer pattern is formed. Further, from the analysis of the height variation of the pattern area, the performance evaluation of each mask and the performance evaluation of the reticle set used in combination can be respectively used to provide an advantage in mass production. This advantage is not limited to color The color filter can be effectively utilized for the manufacture of a product such as a thin film transistor or an organic EL which can be applied with a proximity exposure.

11‧‧‧Transparent substrate

12‧‧‧ shading film

13‧‧‧Photoresist film

100‧‧‧1st mask

101‧‧‧Transparent substrate (substrate for the first mask)

103‧‧‧Abutment

112p‧‧·Transfer pattern

133‧‧‧pattern area

200‧‧‧2nd mask

201‧‧‧Transparent substrate (substrate for second mask)

203‧‧‧Abutment

212p‧‧·Transfer pattern

233‧‧‧pattern area

500‧‧‧Exposure machine

501‧‧‧Light source

502‧‧‧ illumination system

503‧‧‧Support components

Fig. 1 (a) to (j) are flowcharts showing an outline of a manufacturing procedure of the color filter of the embodiment.

Fig. 2(a) is a side view showing a state in which the proximity exposure is performed in the manufacturing process of the color filter of the embodiment, and Fig. 2(b) is a plan view thereof.

Fig. 3(a) is a plan view showing a planar configuration of a photomask according to the embodiment, and Fig. 3(b) is a plan view showing a modification thereof.

4 is a schematic view showing a case where the transfer precision of the pattern on the transfer target on which the transfer pattern is superposed is deteriorated, and FIG. 4(a) is a cross-sectional enlarged view showing the first photomask forming the black matrix layer, FIG. 4 (FIG. 4 (FIG. 4) b) shows a cross-sectional enlarged view of the second photomask forming the red filter layer, and FIG. 4(c) shows a case where the pattern is transferred to the photoresist film.

5(a) to 5(e) are flowcharts showing the steps of manufacturing the photomask of the embodiment.

Fig. 6 is a schematic view showing a case where flatness is measured by obliquely incident laser light.

7(a) to (f) are diagrams showing the relationship between the overlap of the mask and the coordinate shift.

Figure 8 is a diagram illustrating the flatness profile of the major surface.

FIG. 9 is a schematic view showing a state in which the transfer precision of the pattern on the transfer target of the transfer pattern is superposed, and FIG. 9( a ) is an enlarged cross-sectional view showing the first photomask having a specific flatness tendency. 9(b) is an enlarged cross-sectional view showing a second photomask having the same flatness as that of the first photomask, and FIG. 9(c) is a view showing a state in which a pattern is transferred to the photoresist film.

11‧‧‧Transparent substrate

12‧‧‧ shading film

13‧‧‧Photoresist film

100‧‧‧1st mask

101‧‧‧Transparent substrate

103‧‧‧Abutment

112p‧‧·Transfer pattern

500‧‧‧Exposure machine

501‧‧‧Light source

502‧‧‧ illumination system

503‧‧‧ Keeping components

Claims (13)

A substrate for a photomask, which is used for forming a transfer pattern on a main surface to form a photomask, and a maximum value ΔZmax of a height variation of a pattern region on the main surface is 8.5 (μm) the following. The substrate for a photomask according to claim 1, wherein the height of each of the measurement points set at equal intervals in the pattern region by a predetermined distance P is set to Z at the same time The value ΔZmax is the difference between the maximum value and the minimum value of the above Z. The substrate for a photomask according to claim 2, wherein said separation distance P is 5 (mm) ≦ P ≦ 15 (mm). A method of manufacturing a reticle, comprising the steps of: preparing a reticle substrate according to any one of claims 1 to 3, forming an optical film on the main surface of the reticle substrate, The film is patterned to thereby form a transfer pattern. A photomask characterized in that a transfer pattern is formed on a main surface, and a maximum value ΔZmax of a height variation of a pattern region on the main surface is 8.5 (μm) or less. The reticle of claim 5, wherein the height of each of the measurement points is set to Z when the heights of the measurement points set at equal intervals apart from each other by a specific distance P in the pattern region are Δ Zmax is the difference between the maximum value and the minimum value of Z described above. The reticle of claim 6, wherein the separation distance P is 5 (mm) ≦ P ≦ 15 (mm). A reticle according to any one of claims 5 to 7 for use in proximity exposure. The reticle according to any one of claims 5 to 7, which has a pattern for color filter production in the pattern region. A pattern transfer method characterized in that the photomask according to any one of claims 5 to 7 is placed on an exposure machine for proximity exposure, and pattern transfer is performed to the object to be transferred. A substrate kit for a photomask, comprising: a first mask substrate on which a transfer pattern transferred onto a transfer target is formed on a main surface to form a first mask; And a second mask substrate on which the transfer pattern for transferring the transfer pattern onto the transfer target is formed on the main surface to form the second mask, and is set to The height of an arbitrary point M in the pattern region on the main surface of the first mask substrate is set to Zm with respect to the reference surface, and is located in the pattern region on the main surface of the second mask substrate The height of the point N at the position corresponding to the point M on the substrate for the mask is set to Zn with respect to the reference surface, and when the difference Zd between the Zm and the Zn is obtained, the maximum value of the Zd in the pattern region is obtained. ΔZdmax is 17 (μm) or less. A photomask kit comprising a first photomask having a transfer pattern transferred onto a transfer target on a main surface, and a transfer surface formed on the main surface and the transfer surface a second mask that is transferred to the transfer pattern on the transfer target by overlapping printing, and The height of an arbitrary point M in the pattern region set on the main surface of the first mask is set to Zm with respect to the reference surface, and the first region located in the pattern region on the main surface of the second mask is the first The height of the point N at the position corresponding to the point M on the mask is Zn with respect to the reference surface. When the difference Zd between the Zm and the Zn is obtained, the maximum value ΔZdmax of the Zd in the pattern region is 17 (μm) or less. A pattern transfer method comprising: using a exposure machine for proximity exposure, a transfer pattern of the first photomask as claimed in claim 12 and the second photomask as claimed in claim 12; The transfer pattern is superimposedly transferred onto the same transfer target.