JP2018163335A - Photomask and method for manufacturing display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photomask which can achieve both excellent resolution and production efficiency on exposure condition applied to manufacture of a display device.SOLUTION: A pattern for transfer of a photomask is a hole pattern for forming a hole onto a transferred body, and a photomask has a translucent part with a diameter W1 (μm) to which a transparent substrate is exposed, a light-shielding rim part with a width R (μm) surrounding the translucent part, and a phase shift part surrounding the light-shielding rim part. A phase difference with respect to light of a representative wavelength of exposure light between the phase shift part and the translucent part is approximately 180 degrees. In light intensity distribution in which exposure light penetrating through the phase shift part positioned on one side of the translucent part is formed on the transferred body, from a boundary position between the phase shift part and the light-shielding rim part toward the light-shielding rim part, a distance to a minimum value point B1 of a first valley is represented by d1 (μm) and a distance to a minimum value point B2 of a second valley is represented by d2 (μm), condition of (d1-0.5×W1)≤R≤(d2-0.5×W1) is satisfied.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a photomask for manufacturing an electronic device, and particularly to a photomask suitable for manufacturing a flat panel display (FPD), and a method of manufacturing a display device using the photomask.

  As a photomask for manufacturing a semiconductor device, a halftone phase shift mask is known. 11A and 11B show a configuration example of a conventional halftone phase shift mask. FIG. 11A is a schematic plan view, and FIG. 11B is a schematic cross-sectional view at the BB position in FIG.

  In the illustrated halftone phase shift mask, a phase shift film 101 is formed on a transparent substrate 100, and the phase shift film 101 is patterned to form a hole pattern. The hole pattern is composed of a light transmitting portion 103 where the transparent substrate 100 is exposed. A phase shift unit 104 surrounds the hole pattern. The phase shift unit 104 includes a phase shift film 101 formed on the transparent substrate 100.

  The transmittance of the exposure light of the phase shift unit 104 is about 6%, for example, and the phase shift amount is about 180 degrees. At this time, the light transmitted through the light transmitting unit 103 and the light transmitted through the phase shift unit 104 are in opposite phases. These light beams having opposite phases interfere with each other in the vicinity of the boundary between the light transmitting unit 103 and the phase shift unit 104, and have an effect of improving the resolution performance. It is known that such a halftone phase shift mask has an effect of improving not only the resolution performance but also the depth of focus (DOF) as compared with a so-called binary mask.

Isao Tabuchi, Morihisa Homoto, Yoichi Takehana, “Introductory Photomask Technology”, Industrial Research Co., Ltd., December 15, 2006, p. 245

  In display devices including liquid crystal display devices and organic EL (Organic ElectroLuminescence) display devices, it is brighter and more energy-saving, while improving display performance such as high definition, high-speed display, and wide viewing angle. It is desired.

  For example, in the case of a thin film transistor (“TFT”) used in the display device, the contact holes formed in the interlayer insulating film among the plurality of patterns constituting the TFT are surely the upper layer and lower layer patterns. If there is no action to connect, correct operation is not guaranteed. On the other hand, for example, in order to increase the aperture ratio of a liquid crystal display device as much as possible to obtain a bright and power-saving display device, the diameter of the contact hole is required to be sufficiently small. Along with demands, it is desired to reduce the diameter of the hole pattern (for example, less than 3 μm). For example, a hole pattern having a diameter of 0.8 μm or more and 2.5 μm or less, and further a diameter of 2.0 μm or less is required. Specifically, formation of a pattern having a diameter of 0.8 to 1.8 μm is also desired. it is conceivable that.

  By the way, in the field of a photomask for manufacturing a semiconductor device (LSI), which has a higher degree of integration and a remarkably fine pattern than a display device, the exposure device is high in order to obtain high resolution. There is a history of applying an optical system with a numerical aperture NA (for example, exceeding 0.2) to shorten the wavelength of exposure light. As a result, in this field, KrF and ArF excimer lasers (single wavelengths of 248 nm and 193 nm, respectively) have been frequently used.

  On the other hand, in the lithography field for manufacturing a display device, it is not general that the above-described method is applied to improve the resolution. For example, the NA (numerical aperture) of an optical system included in an exposure apparatus used in this field is about 0.08 to 0.12, and about 0.08 to 0.20 is applied even in the future. In the environment. In addition, i-line, h-line, or g-line is often used as an exposure light source, and by using a broad wavelength light source mainly including these, a light amount for irradiating a large area can be obtained, and production efficiency and cost can be reduced. Strong tendency to emphasize.

  Also in the manufacture of display devices, there is an increasing demand for pattern miniaturization as described above. Here, there are some problems in applying the technology for manufacturing a semiconductor device as it is to the manufacture of a display device. For example, conversion to a high-resolution exposure apparatus having a high NA (numerical aperture) requires a large investment and cannot be consistent with the price of the display apparatus. Also, changing the exposure wavelength (using a short wavelength such as ArF excimer laser) is disadvantageous in that it requires considerable investment. In other words, the problem of photomasks for manufacturing display devices is that, while pursuing unprecedented pattern miniaturization, it is not possible to lose cost and efficiency, which are existing merits.

  According to the study by the present inventor, when the halftone phase shift mask shown in FIG. 11 is used as a photomask for manufacturing a display device, there is a problem to be described later and it is clear that there is room for further improvement. became.

  The desired performance for the photomask includes the following elements (1) to (3).

(1) Depth of focus (DOF)
When defocusing occurs during exposure, this refers to the depth of focus for the CD variation within a predetermined range (for example, within ± 10%) with respect to the target CD. If the DOF value is high, the pattern transfer can be performed stably without being affected by the flatness of the transfer target. Here, “CD” is an abbreviation for “Critical Dimension” and is used in the meaning of pattern width. Photomasks for display device manufacture are larger in size than photomasks for semiconductor device manufacture, and the transfer target (display panel substrate, etc.) is also large in size, all of which have perfect flatness Therefore, the significance of a photomask that can increase the numerical value of DOF is great.

(2) Mask error enhancement factor (MEEF)
It is a numerical value indicating the ratio of the CD error on the photomask to the CD error of the pattern formed on the transfer target. In general, as the pattern becomes finer, the CD error on the photomask tends to be enlarged on the transferred object. However, the CD accuracy of the pattern formed on the transferred object can be reduced by suppressing this as much as possible to lower the MEEF. Can be increased. Since the specifications of display devices have evolved, pattern miniaturization is required, and a photomask having a pattern close to the resolution limit of an exposure device is required. There is a high possibility that MEEF will be regarded as important in the future.

(3) Eop
This is the amount of exposure light necessary to form a pattern with a target dimension on the transfer target. In the manufacture of a display device, the size of the photomask substrate is large (for example, a main surface is a rectangle having a side of 300 to 2000 mm). For this reason, when a photomask having a high Eop value is used, it is necessary to reduce the speed of scan exposure, which hinders production efficiency. Therefore, when manufacturing a display device, it is desirable to use a photomask that can reduce the value of Eop.

  According to the study by the present inventor, it has been found that the halftone phase shift mask shown in FIG. 11 can provide an improvement effect of DOF, while further improvement is desired in terms of Eop and MEEF. Specifically, when the halftone phase shift mask is used, the required amount of light (Dose) increases due to loss of light intensity, so that Eop increases significantly, and accordingly, MEEF tends to increase. It has been found that there remains a problem as a photomask for manufacturing a display device.

  Therefore, an object of the present invention is to provide a photomask that can achieve both excellent resolution and production efficiency under the exposure conditions applied to the manufacture of a display device.

(First aspect)
The first aspect of the present invention is:
A photomask for manufacturing a display device having a transfer pattern on a transparent substrate,
The transfer pattern is a hole pattern for forming a hole on a transfer object,
A transparent portion having a diameter W1 (μm) from which the transparent substrate is exposed;
A light shielding rim portion having a width R (μm) surrounding the light transmitting portion;
A phase shift part surrounding the light shielding rim part,
The phase difference between the phase shift portion and the light transmitting portion with respect to light having a representative wavelength of exposure light is approximately 180 degrees,
In the light intensity distribution formed on the transfer medium by the exposure light that passes through the phase shift portion located on one side of the light transmitting portion, the boundary position between the phase shift portion and the light shielding rim portion moves toward the light shielding rim portion side. On the other hand, when the distance to the minimum value point B1 of the first valley is d1 (μm) and the distance to the minimum value point B2 of the second valley is d2 (μm),
(D1-0.5 × W1) ≦ R ≦ (d2-0.5 × W1)
It is a photomask characterized by being.
(Second aspect)
The second aspect of the present invention is:
A photomask for manufacturing a display device having a transfer pattern on a transparent substrate,
The transfer pattern is a hole pattern for forming a hole on a transfer object,
A transparent portion having a diameter W1 (μm) from which the transparent substrate is exposed;
A light shielding rim portion having a width R (μm) surrounding the light transmitting portion;
A phase shift part surrounding the light shielding rim part,
The phase difference between the phase shift portion and the light transmitting portion with respect to light having a representative wavelength of exposure light is approximately 180 degrees,
In the light intensity distribution formed on the transfer medium by the exposure light that passes through the phase shift portion located on one side of the light transmitting portion, the boundary position between the phase shift portion and the light shielding rim portion moves toward the light shielding rim portion side. On the other hand, among the two points indicating 1/2 of the light intensity at the maximum point P of the first mountain, Q1 is a point on the inclined part near the light-shielding rim part of the mountain, and the inclination on the far side When the point in the part is Q2, the distance from the boundary position to Q1 is d3, and the distance to Q2 is d4,
(D3-0.5 × W1) ≦ R ≦ (d4-0.5 × W1)
It is a photomask characterized by being.
(Third aspect)
The third aspect of the present invention is:
The transfer pattern is a hole pattern for forming a hole having a diameter W2 (W2 ≦ W1) on the transfer object, according to the first aspect or the second aspect. This is a photomask.
(Fourth aspect)
The fourth aspect of the present invention is:
The photomask according to any one of the first to third aspects, wherein the phase shift unit has a transmittance of 2 to 10% with respect to the light of the representative wavelength. .
(Fifth aspect)
According to a fifth aspect of the present invention,
The transfer pattern is exposed using a projection exposure apparatus having a numerical aperture (NA) of 0.08 or more and less than 0.20 and having an exposure light source including i-line, h-line, or g-line. The photomask according to any one of the first to fourth aspects, which is used for forming a hole having a diameter W2 of 0.8 to 3.0 (μm) on a transfer target.
(Sixth aspect)
Preparing a photomask according to any one of the first to fourth aspects;
A numerical aperture (NA) of 0.08 to 0.15 is used, and the transfer pattern is exposed using an equal magnification projection exposure apparatus having an exposure light source including i-line, h-line, or g-line. Forming a hole having a diameter W2 of 0.8 to 3.0 (μm) on the transfer body.

  According to the present invention, it is possible to provide a photomask that can achieve both excellent resolution and production efficiency under the exposure conditions applied to the manufacture of a display device.

(A) is a figure which shows the cross section of the conventional halftone type | mold phase shift mask, (b) is a figure which shows the amplitude of the light which permeate | transmitted the phase shift part of the left side of the translucent part in (a). is there. In FIG. 1B, it is a diagram for explaining a consideration about a means for allowing a peak portion whose light phase has turned to the (+) side to pass through a translucent portion and reach the transfer target. 1A and 1B show a configuration example of a photomask according to an embodiment of the present invention, in which FIG. 1A is a schematic plan view, and FIG. 1B is a schematic cross-sectional view taken along line AA in FIG. (A) is a top view which shows a part of pattern for a transfer at the time of setting the width | variety of the light-shielding rim part narrowly in the photomask which concerns on embodiment of this invention, (b) is a photomask in that case FIG. 6 is a diagram (No. 1) showing a light intensity distribution formed on the transfer target by transmitted light that passes through the left phase shift portion. (A) is a top view which shows a part of transfer pattern at the time of setting the width | variety of the light-shielding rim part wide in the photomask which concerns on embodiment of this invention, (b) is a photomask in that case FIG. 6 is a diagram (No. 1) showing a light intensity distribution formed on the transfer target by transmitted light that passes through the left phase shift portion. (A) is a top view which shows a part of pattern for a transfer at the time of setting the width | variety of the light-shielding rim part narrowly in the photomask which concerns on embodiment of this invention, (b) is a photomask in that case FIG. 10 is a diagram (part 2) illustrating a light intensity distribution formed on the transfer target by transmitted light that passes through the left phase shift unit. (A) is a top view which shows a part of transfer pattern at the time of setting the width | variety of the light-shielding rim part wide in the photomask which concerns on embodiment of this invention, (b) is a photomask in that case FIG. 10 is a diagram (part 2) illustrating a light intensity distribution formed on the transfer target by transmitted light that passes through the left phase shift unit. It is a figure which shows the simulation result about the value of MEEF by the change of the width | variety of a light-shielding rim part. It is a figure which shows the simulation result about the value of Eop by the change of the width | variety of a light shielding rim part. When the photomask of the present embodiment (rim width R = 1.0 μm) is exposed by an exposure apparatus, an optical image (that is, the light intensity distribution of transmitted light) formed on the transfer target has the same diameter. It is the figure compared with the binary mask (Binary) which has a hole pattern, and the conventional halftone type phase shift mask (Att.PSM). The structural example of the conventional halftone type | mold phase shift mask is shown, (a) is a plane schematic diagram, (b) is a cross-sectional schematic diagram of the BB position of (a).

  FIG. 1A is a diagram showing a cross section of a conventional halftone phase shift mask, and FIG. 1B shows the amplitude of light transmitted through one phase shift portion of the light transmitting portion in FIG. FIG. FIG. 1B shows the amplitude of the light transmitted through the phase shift unit 104 located on the left side of the light transmitting unit 103. The light transmitted through the phase shift unit 104 located on the right side of the light transmitting part 103 exhibits a transmitted light amplitude that is symmetrical with respect to the transmitted light amplitude in FIG. However, illustration is abbreviate | omitted.

  Here, when the phase of light (not shown) transmitted through the light transmitting portion 103 is (+) phase, the light is transmitted through the phase shift portion 104 and centered from the left boundary of the light transmitting portion 103 on the transfer target. The light reaching the area corresponding to the vicinity has a (−) phase. This light interferes with (+) phase light transmitted through the light transmitting portion 103. For this reason, the intensity | strength of the light which permeate | transmits the translucent part 103 is weakened relatively. That is, the intensity of the light that passes through the light transmitting portion 103 and reaches the transfer target is reduced by the interference between the (+) phase light and the (−) phase light. This phenomenon becomes prominent when the dimension of the light transmitting portion 103 is reduced.

  However, the amplitude curve of the light transmitted through the phase shift unit 104 further shifts from the boundary position to the (+) side on the light transmission unit 103 side (right side in the figure), and the maximum value point of the light amplitude is obtained. Form a mountain with. Therefore, the present inventor uses the (+) phase transmitted light that forms this peak portion to suppress the above-described effect of reducing the light intensity, but rather increase the light intensity, thereby improving Eop and MEEF. The possibility of obtaining was examined.

  FIG. 2 is a view in which the means for positioning the crest portion where the light phase turned to the (+) side in FIG. 1B is located at a position corresponding to the translucent portion on the transferred body. FIG. Here, a light shielding rim portion 105 is formed by a light shielding film 106 near the edge of the phase shift portion 104 on the light transmitting portion 103 side. When the light shielding rim portion 105 is formed in this way, the portion of the phase shift film 101 covered with the light shielding film 106 does not function as the phase shift portion 104. For this reason, the edge of the phase shift unit 104 on the light transmitting part 103 side is shifted to the left as compared with the case where the light shielding rim part 105 is not formed. This means that the light amplitude curve by the phase shift unit 104 is shifted to the left.

  Thereby, in the amplitude curve of the light transmitted through the phase shift unit 104, the peak portion whose phase has turned to the (+) side is shifted to the left side. For this reason, the vicinity of the maximum value point of the amplitude curve forming the mountain can be positioned within the width dimension of the light transmitting portion 103 (preferably, the central position of the light transmitting portion 103 or the vicinity thereof). In this way, the exposure light can be used more efficiently. The present invention has been made based on such knowledge of the present inventors.

<Configuration of Photomask of Embodiment>
3A and 3B show a configuration example of a photomask according to an embodiment of the present invention, in which FIG. 3A is a schematic plan view, and FIG. 3B is a schematic cross-sectional view at the AA position in FIG.

  The illustrated photomask is a photomask for manufacturing a display device provided with a transfer pattern on the transparent substrate 10. This transfer pattern is a hole pattern for forming a hole on the transfer object, and the transparent substrate 10 is exposed, the transparent portion 11 having a diameter W1 (μm), and the width surrounding the transparent portion 11. It has a light shielding rim portion 12 of R (μm) and a phase shift portion 13 surrounding the light shielding rim portion 12. The transparent substrate 10 is made of transparent glass or the like.

  A light shielding film 15 is formed on the transparent substrate 10 in the light shielding rim portion 12. The optical density (OD) of the light shielding film 15 is preferably OD ≧ 2, more preferably OD ≧ 3. The light shielding rim portion 12 may be a single layer of the light shielding film 15 or a laminated film of the phase shift film 14 and the light shielding film 15. There is no particular limitation on the stacking order of the phase shift film 14 and the light shielding film 15 (positional relationship in the thickness direction of the transparent substrate 10). The material of the light shielding film 15 may be Cr or a compound thereof (oxide, nitride, carbide, oxynitride, or oxynitride carbide), or may be a metal compound containing Mo, W, Ta, or Ti. May be. The metal compound may be metal silicide or the above compound of the silicide. The material of the light shielding film 15 is preferably a material that can be wet-etched and has etching selectivity with respect to the material of the phase shift film 14 (described later). Further, the light shielding film 15 and the phase shift film 14 may be provided with a reflection control layer for controlling light reflection on the front surface side and / or the back surface side thereof.

  The phase shift unit 13 is formed by forming a phase shift film 14 on the transparent substrate 10. The phase shift film 14 may be Cr or a compound thereof (oxide, nitride, carbide, oxynitride, or oxynitride carbide), or a metal compound containing Mo, W, Ta, or Ti. Also good. The metal compound may be a metal silicide or the above compound of the silicide. As a material of the phase shift film 14, a material containing any of Zr, Nb, Hf, Ta, Mo, Ti and Si, or an oxide, nitride, oxynitride, carbide, or oxynitride carbide of these materials It may be made of a material containing Si, and may be the above compound of Si. The material of the phase shift film 14 is preferably a material that can be wet-etched.

Here, the phase difference φ1 between the phase shift portion 13 and the light transmitting portion 11 with respect to the light having the representative wavelength of the exposure light is approximately 180 degrees. About 180 degrees means 120 to 240 degrees. The phase difference φ1 is preferably 150 to 210 degrees.
Further, the wavelength dependence of the phase shift amount of the phase shift film is preferably such that the fluctuation range is within 40 degrees with respect to the i-line, h-line, and g-line.

The light-shielding rim portion 12 is a light-shielding film 15 that does not substantially transmit light having a representative wavelength of exposure light, and a film having an optical density OD ≧ 2 (preferably OD ≧ 3) is formed on the transparent substrate 10. It will be. Moreover, it is preferable that the phase shift unit 13 has a transmittance T1 (%) of 2 to 10% with respect to light having a representative wavelength of exposure light. More preferably, it is 3 to 8%, and further preferably 3 <T1 <6. If the transmittance is excessively high, the resist pattern formed on the transfer material is liable to cause a disadvantage that the remaining film thickness is impaired. If the transmittance is too low, the transmission of the inversion phase described below will occur. The contribution of the light intensity curve is difficult to obtain.
Here, the transmittance is the transmittance of light having the above representative wavelength when the transmittance of the transparent substrate 10 is used as a reference (100%). In addition, as the exposure light, light including any of i-line, h-line, and g-line, or broad wavelength light including all of i-line, h-line, and g-line can be used. The representative wavelength is any wavelength (for example, i-line) among wavelengths included in light used for exposure.

In the photomask of this embodiment, the diameter W1 (μm) of the light transmitting portion 11 is preferably 0.8 ≦ W1 ≦ 4.0. In the transfer pattern illustrated in FIG. 3, the planar view shape of the light transmitting portion 11 is a square, and in this case, the diameter W <b> 1 is a dimension of one side of the square. When the planar view shape of the translucent part 11 is a rectangle, the dimension of a long side is set to the diameter W1. The shape of the light transmitting portion 11 is preferably a quadrangle, and particularly preferably a square.
If W1 is too large, the resolution limit dimension of the exposure apparatus for a display device is sufficiently exceeded, so that sufficient resolution can be obtained with a conventional photomask, and the improvement effect of the present invention does not remarkably occur. On the other hand, if W1 is too small, it is difficult to obtain a stable and accurate CD during photomask manufacturing. More preferably, 0.8 ≦ W1 ≦ 3.5. If further miniaturization is desired, 1.0 <W1 <3.0, or 1.2 <W1 <2.5 may be satisfied.

  In the case where a hole having a diameter W2 (μm) is formed on the transfer target by the transfer pattern provided in the photomask of this embodiment, preferably 0.8 ≦ W2 ≦ 3.0. The diameter W2 of the hole formed on the transferred body is the length of the largest portion of the distance between the two opposing sides.

  That is, the relationship between the diameter W1 of the translucent portion 11 of the photomask and the diameter W2 of the hole of the transfer target is preferably W1 ≧ W2, and more preferably W1> W2. When β (μm) is a mask bias value (W1-W2) and β> 0 (μm), the bias value β (μm) is preferably 0.2 ≦ β ≦ 1.0, and more Preferably, 0.2 ≦ β ≦ 0.8.

  FIG. 4A shows a part of the transfer pattern (portion surrounded by a dotted line in FIG. 3) when the width of the light-shielding rim portion is set relatively narrow in the photomask according to the embodiment of the present invention. FIG. 4B is a diagram illustrating a light intensity distribution formed on the transfer target by transmitted light that passes through the phase shift portion on the left side of the photomask in that case. FIG. 5A shows a part of the transfer pattern when the width of the light-shielding rim part is set relatively wide in the photomask according to the embodiment of the present invention (the part surrounded by the dotted line in FIG. 3). FIG. 6B is a diagram showing a light intensity distribution formed on the transferred body by transmitted light that passes through the phase shift portion on the left side of the photomask in that case.

  As shown in FIGS. 4B and 5B, the light intensity formed on the transfer target by the exposure light that passes through the phase shift unit 13 located on one side (left side in the drawing) of the light transmitting unit 11. When the distribution is drawn with a curve, the first valley, the first mountain, and the second valley are formed from the boundary position between the phase shift unit 13 and the light shielding rim portion 12 toward the light shielding rim portion 12 side (right side in the drawing). Appear. The first peak corresponds to the peak of the portion where the phase turns to the (+) side in the light amplitude curve shown in FIG.

Here, the distance from the boundary position to the minimum value point B1 (FIG. 4) of the first valley is d1 (μm), and the distance to the minimum value point B2 (FIG. 5) of the second valley is d2 ( μm), the width R (μm) of the light shielding rim portion 12 is preferably set so as to satisfy the following expression (1).
(D1-0.5 × W1) ≦ R ≦ (d2-0.5 × W1) (1)
4 shows the lower limit of the width R of the light shielding rim portion 12 in the above equation (1), and FIG. 5 shows the upper limit.

  When the width R of the light shielding rim portion 12 is set so as to satisfy the above formula (1), the transmitted light having the (+) phase among the transmitted light of the phase shift portion 13 can be positioned at the center of the light transmitting portion 11. it can. That is, of the transmitted light transmitted through the phase shift unit 13, at least a part of the (+) phase portion is caused to reach the transferred body together with the transmitted light of the (+) phase transmitted through the light transmitting unit 11. An effect of increasing the peak of the light intensity can be obtained.

  Next, a pattern configuration for causing more of the (+) phase of the transmitted light transmitted through the phase shift unit 13 to reach the transfer target will be considered with reference to FIGS. 6 and 7.

  FIG. 6A shows a part of the transfer pattern (portion surrounded by a dotted line in FIG. 3) when the width of the light-shielding rim portion is set relatively narrow in the photomask according to the embodiment of the present invention. FIG. 4B is a diagram illustrating a light intensity distribution formed on the transfer target by transmitted light that passes through the phase shift portion on the left side of the photomask in that case. FIG. 7A shows a part of a transfer pattern (a part surrounded by a dotted line in FIG. 3) when the width of the light-shielding rim part is set relatively wide in the photomask according to the embodiment of the present invention. FIG. 6B is a diagram showing a light intensity distribution formed on the transferred body by transmitted light that passes through the phase shift portion on the left side of the photomask in that case.

As shown in FIGS. 6B and 7B, the light intensity formed on the transfer target by the exposure light that passes through the phase shift unit 13 located on one side (left side in the drawing) of the light transmitting unit 11. When the distribution is drawn in a curved line, the first valley, the first mountain, the first peak from the boundary position between the phase shift unit 13 and the light shielding rim portion 12 toward the light shielding rim portion 12 side (right side in the figure), as described above. A valley of 2 appears.
In this case, of the two points indicating ½ of the light intensity at the local maximum point P of the first mountain, the slope is on the side closer to the light shielding rim portion 12 (left side in the figure) of the first mountain. The point is Q1, the point on the far side (right side in the figure) is Q2, the distance from the boundary position to Q1 is d3 (FIG. 6), and the distance to Q2 is d4 (FIG. 7). At this time, the width R (μm) of the light shielding rim portion 12 is preferably set so as to satisfy the following expression (2).
(D3-0.5 × W1) ≦ R ≦ (d4-0.5 × W1) (2)
6 shows the lower limit of the width R of the light shielding rim portion 12 in the equation (2), and FIG. 7 shows the upper limit.

  When the width R of the light shielding rim portion 12 is set so as to satisfy the above expression (2), the portion of the transmitted light of the phase shift portion 13 that is in the (+) phase and has a high light intensity (about half above) Can be positioned at the center of the light transmitting portion 11. That is, of the transmitted light that passes through the phase shift unit 13, a portion close to the peak of the (+) phase peak (maximum point P) is surely positioned near the center in the dimension of the light transmitting unit 11 to be transferred. An effect of increasing the peak of the light intensity more efficiently can be obtained.

According to the photomask of this embodiment, among the amplitude curves of the light transmitted through the phase shift unit 13, the position of the peak portion that has changed to the (+) phase is shifted, and more of the (+) phase peaks. The portion can be positioned within the dimension of the light transmitting portion 11. This makes it possible to use the exposure light more efficiently. As a result, it is possible to achieve both excellent resolution and production efficiency under the exposure conditions applied to the manufacture of the display device. Specifically, for example, in an exposure condition where the numerical aperture (NA) is 0.08 ≦ NA ≦ 0.20 and the coherence factor (σ) is 0.4 ≦ σ ≦ 0.9, a photo excellent in MEEF and Eop. A mask can be realized.
More preferably, 0.08 <NA <0.20.
Furthermore, 0.10 <NA <0.15
It is desirable that
More preferably,
0.4 <σ <0.7
More preferably,
0.4 <σ <0.6
It is.
The transfer pattern included in the photomask of this embodiment is for forming holes on the transfer target, and surrounds the light-transmitting portion having a diameter W1 (μm) with the transparent substrate exposed and the light-transmitting portion. , A light shielding rim portion having a width R (μm) and a phase shift portion surrounding the light shielding rim portion. In other words, the MEEF and Eop improving effects can be obtained without including other configurations (such as auxiliary patterns for assisting transferability) for forming the holes.
The photomask of this embodiment is suitably used as a photomask for forming isolated holes on the transfer target. Alternatively, a photomask for forming dense holes on the transfer target can be used. A dense hole is one in which a plurality of hole patterns are regularly arranged and have an optical effect on each other.

  The present invention includes a method for manufacturing a display device, in which the photomask of the present embodiment is used for exposure by an exposure apparatus, and the transfer pattern is transferred onto a transfer target.

  In the display device manufacturing method of the present invention, first, the photomask of this embodiment is prepared. Next, the transfer pattern is exposed using an exposure apparatus to form holes having a diameter W2 of 0.8 to 3.0 (μm) on the transfer target. For exposure, an exposure apparatus having a numerical aperture (NA) of 0.08 to 0.20 and an exposure light source including i-line, h-line, or g-line is used. The exposure is a projection exposure apparatus that performs projection exposure at the same magnification, and the numerical aperture (NA) of the optical system is 0.08 to 0.15 (coherence factor (σ) is 0.4 to 0.9. It is preferable to use an exposure apparatus having an exposure light source that includes at least one of i-line, h-line, and g-line in exposure light. When applying a single wavelength as the exposure light, it is preferable to use i-line. Further, the exposure light may be broad wavelength light including all of i-line, h-line, and g-line. The light source of the exposure apparatus to be used may use oblique illumination (annular illumination or the like) excluding the normal incident component, but the present invention may be applied to normal illumination including the normal incident component without applying oblique illumination. The excellent effect of is sufficiently obtained.

The photomask according to the embodiment of the present invention is manufactured, for example, by preparing a photomask blank having a structure in which the phase shift film 14 and the light shielding film 15 are sequentially laminated on the transparent substrate 10 and then patterning both films. Can do. For the formation of the phase shift film 14 and the light shielding film 15, a known film formation method such as a sputtering method may be applied. In manufacturing a photomask, a known lithography can be used in a photolithography process, and a laser drawing apparatus or the like can be used. When the photomask of FIG. 3 is manufactured, it is desired that the width R of the light shielding rim portion 12 be precisely controlled. This is because the profile of the aerial image formed on the transfer medium during exposure is affected.
Preferably, when the photomask of FIG. 3 is manufactured, drawing is performed on the photomask blank on which the resist film is formed, and the light shielding film 15 is first etched to form the light shielding rim portion 12 (light shielding rim portion). Next, it is preferable that a resist film is formed again and drawing is performed to etch the phase shift film 14 to form the light transmitting portion 12.

Next, an optical simulation performed using the photomask according to the embodiment of the present invention will be described.
In the optical simulation, a photomask having a transfer pattern (hole pattern) similar to that shown in FIG. 3 was used. In this case, when the diameter W1 of the light transmitting portion 11 is 2 μm and a hole having a W2 of 1.5 μm is transferred onto the transfer target (bias β = 0.5 μm), depending on the width R of the light shielding rim portion 12 We examined how the optical performance of MEEF and Eop changes. Note that the transmittance of the exposure light of the phase shift unit 13 is 5.2% with respect to the i line.

The optical conditions used for the simulation are as follows.
The optical system of the exposure apparatus has a numerical aperture NA of 0.1 and a coherence factor σ of 0.5. Further, a light source (broad wavelength light source) including all of i-line, h-line, and g-line was used as the exposure light source, and the intensity ratio was g: h: i = 1: 1: 1.

  FIG. 8 is a diagram showing a simulation result for the MEEF value due to a change in the width of the light shielding rim portion, and FIG. 9 is a diagram showing a simulation result for the Eop value due to a change in the width of the light shielding rim portion. 8 and 9, Rim Size (μm) on the horizontal axis represents the width R of the light shielding rim portion 12. The case where the width R of the light shielding rim portion 12 is 0 corresponds to the case where the conventional halftone phase shift mask similar to that shown in FIG. 11 is used.

  According to FIG. 8, the MEEF value fluctuates due to the change in the width R of the light-shielding rim portion 12. In particular, when the width R is 0.5 to 1.5 μm, the MEEF value is less than 6, and the width It can be seen that when R is 0.5 to 1.0 μm, the MEEF value is further suppressed. The value of MEEF at this time is lower than 5.25, and is a value lower than half compared to a conventional halftone phase shift mask having a translucent portion (hole pattern) having the same diameter W1.

  Further, according to FIG. 9, the photomask of the present embodiment has a significantly reduced Eop compared to the conventional halftone phase shift mask, and in particular, the width R of the light shielding rim portion 12 is 0.5 to 2.0 μm. It can be seen that the amount of dose required for exposure is reduced by 25% or more over the range. In particular, when the width of the light shielding rim portion 12 is 0.75 to 1.5, it is reduced by 35% or more.

  FIG. 10 shows an optical image (that is, an image formed on a transfer target when the photomask of the present embodiment used in the simulation (with a rim width R = 1.0 μm) is exposed by an exposure apparatus (that is, It is the figure which compared the light intensity distribution of the transmitted light with the binary mask (Binary) which has the hole pattern of the same diameter, and the conventional halftone type phase shift mask (Att.PSM).

  According to FIG. 10 described above, the aerial image formed by the photomask of this embodiment has a higher peak than the aerial image formed by other photomasks, and has a steeper slope (nearly vertical), and a fine hole. It can be seen that this is an excellent profile that is advantageous for forming.

DESCRIPTION OF SYMBOLS 10 ... Transparent substrate 11 ... Translucent part 12 ... Light shielding rim part 13 ... Phase shift part 14 ... Phase shift film 15 ... Light shielding film

Claims (6)

A photomask for manufacturing a display device having a transfer pattern on a transparent substrate,
The transfer pattern is a hole pattern for forming a hole on a transfer object,
A transparent portion having a diameter W1 (μm) from which the transparent substrate is exposed;
A light shielding rim portion having a width R (μm) surrounding the light transmitting portion;
A phase shift part surrounding the light shielding rim part,
The phase difference between the phase shift portion and the light transmitting portion with respect to light having a representative wavelength of exposure light is approximately 180 degrees,
In the light intensity distribution formed on the transfer medium by the exposure light that passes through the phase shift portion located on one side of the light transmitting portion, the boundary position between the phase shift portion and the light shielding rim portion moves toward the light shielding rim portion side. On the other hand, when the distance to the minimum value point B1 of the first valley is d1 (μm) and the distance to the minimum value point B2 of the second valley is d2 (μm),
(D1-0.5 × W1) ≦ R ≦ (d2-0.5 × W1)
A photomask characterized by being. A photomask for manufacturing a display device having a transfer pattern on a transparent substrate,
The transfer pattern is a hole pattern for forming a hole on a transfer object,
A transparent portion having a diameter W1 (μm) from which the transparent substrate is exposed;
A light shielding rim portion having a width R (μm) surrounding the light transmitting portion;
A phase shift part surrounding the light shielding rim part,
The phase difference between the phase shift portion and the light transmitting portion with respect to light having a representative wavelength of exposure light is approximately 180 degrees,
In the light intensity distribution formed on the transfer medium by the exposure light that passes through the phase shift portion located on one side of the light transmitting portion, the boundary position between the phase shift portion and the light shielding rim portion moves toward the light shielding rim portion side. On the other hand, among the two points indicating 1/2 of the light intensity at the maximum point P of the first mountain, Q1 is a point on the inclined part near the light-shielding rim part of the mountain, and the inclination on the far side When the point in the part is Q2, the distance from the boundary position to Q1 is d3, and the distance to Q2 is d4,
(D3-0.5 × W1) ≦ R ≦ (d4-0.5 × W1)
A photomask characterized by being.   3. The photomask according to claim 1, wherein the transfer pattern is a hole pattern for forming a hole having a diameter W2 (W2 ≦ W1) on the transfer target.   The photomask according to claim 1, wherein the phase shift unit has a transmittance of 2 to 10% with respect to the light of the representative wavelength.   The transfer pattern is exposed using an equal magnification projection exposure apparatus having a numerical aperture (NA) of 0.08 to 0.20 and having an exposure light source including i-line, h-line, or g-line. The photomask according to any one of claims 1 to 4, which is used for forming a hole having a diameter W2 of 0.8 to 3.0 (µm) on a transfer body. Preparing the photomask according to any one of claims 1 to 5,
The transfer pattern is exposed using an equal magnification projection exposure apparatus having a numerical aperture (NA) of 0.08 to 0.20 and having an exposure light source including i-line, h-line, or g-line. Forming a hole having a diameter W2 of 0.8 to 3.0 (μm) on the transfer body.