JP2017033004A - Photomask for manufacturing display device, method for manufacturing the photomask, method for pattern transfer, and method for manufacturing display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photomask for manufacturing a display device, having improved fine pattern transferability.SOLUTION: Provided is a photomask for manufacturing a display device, obtained by forming a transfer pattern containing a light-shielding part 15, a phase shift part 16, and a transmissive part 17. The light-shielding part is formed by laminating a phase shift film, an etching mask film, and a light-shieling film in this order. The phase shift part is either a phase shift film or is formed by laminating a phase shift film and an etching mask film in this order. The transmissive part is formed by exposing a surface of a transparent substrate 11. The phase shift film is formed of a material containing chromium, and the etching mask film is formed of a material having etching resistance against an etchant for the phase shift film. The phase shift part 16 and the transmissive part 17 have an adjacent portion, and the phase shift part and the transmissive part have a phase difference of about 180 degree in relation to a representative wavelength of exposure light through the photomask.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a photomask for manufacturing a display device capable of forming a fine pattern in manufacturing the display device, a method for manufacturing the photomask, a pattern transfer method using the photomask, and a method for manufacturing the display device.

  Patent Document 1 describes an invention relating to a method of manufacturing a phase shift mask capable of forming a fine and highly accurate exposure pattern. In this document, since the glass substrate for a flat panel has a size exceeding 300 mm, it is described that the waviness and surface roughness of the substrate become large and are easily affected by the depth of focus.

  Therefore, Patent Document 1 gives a phase difference of 180 ° to any light in a wavelength region of 300 nm or more and 500 nm or less by patterning a light shielding layer on a transparent substrate and sputtering a target of a chromium-based material. A phase shift layer is formed on the transparent substrate so as to cover the light shielding layer, and a method of manufacturing a phase shift mask is described in which the phase shift layer is patterned.

  Patent Document 2 is an FPD manufacturing photomask in which a blind region includes a light-shielding region and a light-transmitting region, and a main region includes a phase-inversion region and a light-transmitting region. The blind region is formed on a transparent substrate. A light shielding film pattern and a phase inversion film are laminated, and the light-transmitting area of the blind area includes the transparent substrate area exposed by sequentially etching the phase inversion film and the light shielding film pattern, and the main area The transparent region includes the transparent substrate region exposed by etching the phase inversion film stacked on the transparent substrate, and the light shielding film pattern has an etching rate of the phase inversion film with respect to the same etching substance. A photomask is described that is faster than the etch rate.

JP 2011-13283 A JP 2012-230379 A

  Currently, a VA (Vertical alignment) system, an IPS (In Plane Switching) system, and the like are employed in liquid crystal display devices. By adopting these, it is desired to improve display performance such as high definition, high speed display, and wide viewing angle as well as being bright and energy saving.

  For example, in a liquid crystal display device to which these methods are applied, a transparent conductive film formed in a line-and-space pattern is applied to the pixel electrode, and in order to improve the display performance of the display device, these patterns are increasingly miniaturized. Is desired. For example, it is desired that the pitch width P (the total of the line width L and the space width S) of the line and space pattern is narrowed from 6 μm to 5 μm, and further from 5 μm to 4 μm. In this case, at least one of the line width L and the space width S is often less than 3 μm. For example, there are many cases where L <3 μm, or L ≦ 2 μm, or S <3 μm, or S ≦ 2 μm.

  On the other hand, in the case of a thin film transistor (“TFT”) used in a liquid crystal display device or an EL display device, a contact hole formed in a passivation (insulating layer) among a plurality of patterns constituting the TFT is insulated. The structure which penetrates the layer and conducts to the connecting portion on the lower layer side is adopted. At this time, if the patterns on the upper layer side and the lower layer side are accurately positioned and the shape of the contact hole is not reliably formed, correct operation of the display device cannot be guaranteed. Also in this case, it is necessary to increase the integration of device patterns as well as to improve the display performance, and there is a demand for pattern miniaturization. That is, the diameter of the hole pattern is required to be less than 3 μm. For example, a hole pattern with a diameter of 2.5 μm or less and further with a diameter of 2.0 μm or less is required, and in the near future, formation of a pattern with a diameter of 1.5 μm or less, which is less than this, is considered desirable.

  Against this background, there is an increasing need for a photomask for manufacturing a display device that can cope with the miniaturization of line and space patterns and contact holes.

  By the way, in the field of photomasks for manufacturing semiconductors (LSIs, etc.), in order to obtain resolution, phase shift masks utilizing phase shift action have been developed together with optical systems with high NA (for example, 0.2 or more). There is a background. Phase shift masks are used with single-wavelength, short-wavelength light sources (such as KrF or ArF excimer lasers). This has coped with the high integration of various elements and the accompanying miniaturization of the photomask pattern.

  On the other hand, in the lithography field for manufacturing display devices, it has not been common to apply the above-described method for improving resolution and expanding the depth of focus. The reason for this is that the degree of pattern integration and fineness required in display devices were not as good as those in the semiconductor manufacturing field. Actually, the optical system and light source mounted on an exposure apparatus for manufacturing a display device (generally known as an LCD exposure apparatus or a liquid crystal exposure apparatus) are different from those for semiconductor manufacturing, and resolution and depth of focus. Therefore, production efficiency (for example, widening the wavelength range of the light source to obtain a large amount of irradiation light and shortening the production tact) has been emphasized.

  When the transfer pattern of the photomask is miniaturized, it becomes difficult to perform a process of accurately transferring the pattern to a transfer target (also referred to as a target to be etched, such as a thin film to be etched). The resolution limit of the above-described exposure apparatus that is actually used in the transfer process in the manufacture of the display device is about 3 μm. However, in the transfer pattern necessary for the display device, as described above, the CD ( This is because the critical dimension (line width) is already close to or less than this.

  Furthermore, since the mask for manufacturing a display device has a larger area than the mask for manufacturing a semiconductor, it has been difficult to transfer a transfer pattern having a CD of less than 3 μm uniformly in the surface in actual production.

  If a mask for manufacturing a display device is used in this way, it is difficult to transfer a fine pattern such as a CD of less than 3 μm. Therefore, the resolution improvement that has been developed for the purpose of manufacturing a semiconductor device has been developed. It is conceivable to apply various methods for the display device manufacturing field.

  However, there are some problems in applying the above-described method as it is to manufacturing a display device. For example, conversion to a high-resolution exposure apparatus having a high NA (numerical aperture) requires a large investment, and there is a discrepancy in consistency with the price of the display apparatus. Or, it is difficult to change the exposure wavelength (using a short wavelength such as ArF excimer laser as a single wavelength) for a display device having a relatively large area, or the manufacturing tact is likely to be extended. In addition, it is disadvantageous in that it requires considerable investment.

  Therefore, if the transferability of the fine pattern can be improved by devising the transfer pattern provided in the photomask for manufacturing the display device, it is very significant.

The gist of the present invention is as follows.
<1> On the transparent substrate, the phase shift film, the etching mask film, and the light shielding film are patterned by wet etching, thereby forming a transfer pattern including the light shielding part, the phase shift part, and the light transmitting part. A photomask for manufacturing a display device,
The light shielding portion is formed by laminating the phase shift film, the etching mask film, and the light shielding film in this order on the transparent substrate.
The phase shift portion is formed by forming the phase shift film or the phase shift film and the etching mask film on the transparent substrate,
The transparent portion is formed by exposing the transparent substrate surface,
The phase shift film is made of a material containing chromium,
The etching mask film is made of a material having etching resistance to the etching solution of the phase shift film,
The phase shift portion and the light transmitting portion have adjacent portions, and the phase shift portion and the light transmitting portion have a phase difference of about 180 degrees with respect to a representative wavelength of exposure light of the photomask. With
Photomask for display device manufacturing.

  <2> The transfer pattern includes a line and space pattern, and the line pattern of the line and space pattern includes a constant width light shielding portion, and a constant width phase shift portion adjacent to both sides of the constant width light shielding portion. The photomask for manufacturing a display device according to <1>, wherein

  <3> The transfer pattern includes a hole pattern, and the hole pattern includes a light-transmitting portion having a predetermined diameter, a phase shift portion having a constant width surrounding the light-transmitting portion, and a light-shielding portion surrounding the phase shift portion. The photomask for manufacturing a display device according to <1>, characterized by comprising:

<4> The phase shift portion is formed by forming the phase shift film on the transparent substrate,
The photomask for manufacturing a display device according to any one of <1> to <3>, wherein the phase shift film has a phase shift of about 180 degrees with respect to a representative wavelength of the exposure light.

<5> The phase shift portion is formed by laminating the phase shift film and the etching mask film in this order on the transparent substrate.
The lamination of the phase shift film and the etching mask film is a phase shift of approximately 180 degrees with respect to the representative wavelength of the exposure light, wherein any one of <1> to <3> Photomask for manufacturing display devices.

<6> In the portion where the translucent portion and the phase shift portion are included in the transfer pattern, the etched surface of the phase shift film is exposed,
In the cross section of the adjacent portion, the upper side, the lower side, and the side side corresponding to the upper surface, the lower surface, and the etched surface of the phase shift film satisfy the following conditions (A) and (B), <1> to <5 > The photomask for manufacturing a display device according to any one of the above.
(A) A straight line connecting a contact point between the upper side and the side side and a position of the side side at a height that is two-thirds lower than the film thickness of the phase shift film from the upper surface, The angle between the upper side is in the range of 85 to 120 degrees, and
(B) a first imaginary line that passes through the contact point between the upper side and the side side and is perpendicular to the main surface of the transparent substrate, and a height that is one tenth of the film thickness above the lower surface; The width of the second virtual line passing through the position of the side and perpendicular to the main surface of the transparent substrate is less than or equal to half of the film thickness.

<7> On the transparent substrate, the phase shift film, the etching mask film, and the light shielding film are patterned by wet etching, thereby forming a transfer pattern including the light shielding part, the phase shift part, and the light transmitting part. A method of manufacturing a photomask for manufacturing a display device,
The light shielding portion is formed by laminating the phase shift film, the etching mask film, and the light shielding film in this order on the transparent substrate.
The phase shift portion is formed by forming the phase shift film or the phase shift film and the etching mask film on the transparent substrate,
In the method of manufacturing a photomask for manufacturing a display device in which the transparent substrate surface is exposed,
A step of preparing a photomask blank in which a phase shift film, an etching mask film, and a light shielding film are laminated in this order on the transparent substrate, and further a first photoresist film is formed;
Forming a pattern for transfer by performing predetermined patterning on the phase shift film, the etching mask film, and the light shielding film, respectively.
The patterning of the phase shift film includes a step of wet etching the phase shift film using the patterned etching mask film as a mask,
The phase shift film is made of a material containing chromium,
The etching mask film is made of a material having etching resistance to the etching solution of the phase shift film,
The phase shift portion and the light transmitting portion have adjacent portions, and the phase shift portion and the light transmitting portion have a phase difference of about 180 degrees with respect to a representative wavelength of exposure light of the photomask. It is characterized by having
A method for manufacturing a photomask for manufacturing a display device.

<8> A step of preparing a photomask for manufacturing a display device according to <1>,
Using a display device manufacturing exposure apparatus that irradiates exposure light including i-line, h-line, and g-line, the transfer pattern included in the photomask is exposed, and the transfer pattern is transferred onto the transfer target. A pattern transfer method.

<9> A step of preparing a photomask for manufacturing a display device according to <1>,
Using a display device manufacturing exposure apparatus that irradiates exposure light including i-line, h-line, and g-line, the transfer pattern included in the photomask is exposed, and the transfer pattern is transferred onto the transfer target. The manufacturing method of a display apparatus including the process to do.

  According to the present invention, a photomask for manufacturing a display device capable of forming a fine pattern as designed in manufacturing the display device, a method for manufacturing the photomask, a pattern transfer method using the photomask, and a display A method of manufacturing a device is provided.

Schematic diagram (FIG. 1 (a)) of a top view of a phase shift mask of a line-and-space pattern in a simulation performed on a difference in phase shift effect due to a difference in cross-sectional shape of the phase shift film pattern, and a partial cross-sectional schematic diagram thereof FIG. 1B is a cross-sectional schematic diagram (FIG. 1C) of a phase shift mask of another shape (FIG. 1B) and a schematic cross-sectional diagram of a binary mask used for comparison (FIG. 1D). 3 is a light intensity distribution curve formed on a transfer target when exposure is performed using the three types of photomasks used in the simulation. It is a cross-sectional schematic diagram of the photomask blank prepared in the case of manufacture of the photomask of this invention. Sectional view (lower side) and corresponding top view (upper side) of the photomask of the present invention according to the first aspect (FIG. 4A), and photomask of the present invention according to the second aspect (FIG. b)) is a cross-sectional view (lower side) and a corresponding top view (upper side). The photomask of the present invention according to the first aspect (FIGS. 5A and 5B), and the photomask of the present invention according to the second aspect (FIG. 5C), in which the transfer pattern is a hole pattern. (D)) is a top view and a cross-sectional view. It is a figure for demonstrating the to-be-etched surface (side surface) shape of the patterned phase shift film. It is a figure which shows the example of the manufacturing method of the photomask of this invention by the 1st and 2nd aspect. It is a figure which shows the example of the manufacturing method of the photomask of this invention by the 1st and 2nd aspect. It is a figure which shows the example of the manufacturing method of the photomask of this invention of the 1st aspect using side etching. It is a cross-sectional photograph of a phase shift film pattern obtained when wet etching is performed using a resist pattern as a mask.

  In order to reliably transfer a fine pattern in the photolithography process, the light intensity distribution given to the resist film on the transfer target by the exposure process using a photomask is important. That is, if the contrast of the light intensity distribution curve is high and the profile of the resist pattern formed on the transferred body is improved, the etching process of the transferred body such as a display device substrate can be made more precise using this resist pattern. Yes. In a photomask for a display device, it is generally important that the area is large (300 mm or more on one side), that patterning can be performed uniformly over the entire surface, and that the uniformity of CD within the surface can be controlled. The shape of the light intensity distribution curve created by is particularly important.

  By the way, the above Patent Documents 1 and 2 describe that a photomask having a phase shift layer (or a phase inversion layer) is used in order to form a fine and highly accurate pattern or to obtain a high resolution. ing.

  According to Patent Document 1, a light-shielding film is formed on a transparent substrate with a chromium-based material or the like, and after etching the light-shielding film into a predetermined shape, a phase shift layer of a chromium-based material is formed so as to cover it, The phase shift layer is patterned using a photoresist resist pattern formed on the phase shift layer as a mask. Also. Also in Patent Document 2, a photomask is formed by etching a phase inversion film containing chromium formed on a light shielding film pattern containing chromium.

  Here, when the phase shift layer (or phase inversion film) is etched using the resist pattern as a mask, the phase shift film is expected to be faithfully patterned with respect to the resist pattern. However, the inventors have found that there are the following problems when wet etching is applied.

  For example, in order to perform desired patterning on a phase shift film containing chromium (hereinafter also referred to as a chromium phase shift film), a cross-section of the phase shift film pattern obtained when wet etching is performed using a resist pattern as a mask is illustrated. 10 shows. FIG. 10 is a cross-sectional photograph of the phase shift film pattern 102 obtained by etching the phase shift film made of CrOCN formed on the transparent glass substrate 101 using the resist pattern 103 of the positive photoresist as a mask.

  As is clear from FIG. 10, the cross section of the phase shift film (PS film) pattern 102 that is in contact with the etching solution is not perpendicular to the surface of the transparent glass substrate 101 but is greatly inclined (hereinafter also referred to as a taper shape). ) Was observed. This is because the adhesiveness at the interface between the phase shift film pattern 102 and the resist pattern 103 is insufficient, and etching proceeds faster on the upper surface side of the film than on the lower surface side (substrate side). This is because (the etching in the right direction in FIG. 10) proceeds.

  By the way, for the purpose of increasing the contrast of the transferred image and improving the depth of focus by utilizing the phase inversion of the transmitted light at the boundary between the light transmitting portion through which the exposure light is transmitted and the light shielding portion that attempts to shield the exposure portion. Photomasks having a phase shift effect are often used mainly in the field of semiconductor manufacturing. These phase shift masks have a transmittance of about 5 to 10% with respect to exposure light (for example, KrF or ArF excimer laser), and a phase shift film that shifts the phase of the exposure light by about 180 degrees. It is known to use.

  However, since photomasks (phase shift masks) used in this field are generally manufactured by applying dry etching, the problems caused by adopting the above-described wet etching have never become obvious. However, as described above, a photomask for manufacturing a display device has a relatively large size (uses a rectangular substrate having a side of 300 mm or more (usually 1800 mm or less)), and has various types of sizes. For this reason, it is advantageous to apply wet etching rather than using dry etching.

  On the other hand, in a photomask for manufacturing a display device, a multi-tone photomask having a transfer pattern having a semi-transparent part that partially transmits exposure light in addition to a light-shielding part and a translucent part is conventionally used. It has been. This photomask is a resist formed on a transfer medium by making the light transmittances of the light transmitting portion, the light shielding portion, and the semi-light transmitting portion different from each other (substantially zero in the light shielding portion). A three-dimensional level difference is formed in the pattern shape, and by using this, the number of steps when processing the transfer object is reduced.

  The semi-transparent portion in the multi-tone photomask is created by forming a semi-transparent film (a film having a transmittance that transmits about 20 to 80% of exposure light) on a transparent substrate. Sometimes.

  However, in the manufacture of such a multi-tone photomask, the phase difference of the exposure light transmitted through each of the translucent part and the translucent part is not set to about 180 degrees. If the phase difference is close to 180 degrees, a substantially light-shielding line pattern is generated at this boundary portion, and there is a problem that the three-dimensional shape of the resist pattern to be obtained cannot be obtained.

  That is, in the photomask for manufacturing a display device, the problem due to the fact that the cross section of the semi-transparent film is inclined with respect to the substrate surface has never been realized.

  The inventors of the present invention have no influence on the transferability of the photomask by forming a cross-sectional shape of the photomask that is not etched perpendicular to the surface of the substrate and forming an inclined cross-sectional shape. A simulation was conducted to see if That is, the phase shift effect obtained by reversing the phases of the exposure light passing through each of the photomask transfer patterns at the boundary between the light transmitting portion and the phase shift portion and interfering with each other is the effect of the phase shift film. We examined how it changes depending on the cross-sectional shape to be etched.

<Simulation results>
Before describing the embodiment of the present invention, the difference in phase shift effect due to the difference in cross-sectional shape of the phase shift film pattern will be described using the results of the simulation.

  The simulation was performed by applying the optical conditions of the exposure apparatus for manufacturing the display device. Broad wavelength light including an optical system having a numerical aperture (NA) of 0.085, a coherence factor (σ) of 0.9, exposure light of g-line, h-line and i-line (intensity ratio is g-line: h-line: i-line = 0.95: 0.8: 1.0).

This simulation
A phase shift mask (PSM (A)) having a phase shift film pattern in which the cross-sectional shape of the edge portion is vertical,
A phase shift mask (PSMTP (A)) modeled on the phase shift film pattern of FIG.
Binary mask (Bin)
Went about. The schematic diagram of each cross section is shown in FIGS.

  FIG. 1A is a schematic top view of the line and space pattern used in this simulation, and shows a part of the line and space pattern in PSM (A). FIG. 1B is a view showing a cross section of a part of the phase shift mask having the line and space pattern.

  As shown in FIG. 1B, the phase shift mask PSM (A) has a phase shift film pattern 12a formed on the transparent substrate 11, an etching mask film pattern 13a formed thereon, and A light shielding film pattern 14a is formed thereon. In this top view (that is, FIG. 1A), the portion of the light shielding film pattern 14a is the light shielding portion 15, and a part of the phase shift film pattern 12a that is not covered with the light shielding film pattern 14a is the phase shift. The exposed portion of the transparent substrate 11 that is not laminated on the transparent substrate 11 constitutes the light transmitting portion 17.

  The phase shift mask PSM (A) is a line and space pattern having a line width L of 2.0 μm and a space width S of 2.0 μm (pitch P is 4.0 μm). The line pattern 2a has a width of 1.0 μm. Phase shift portions 16 each having a width of 0.5 μm are provided on both edges of the light shielding portion 15. The space patterns 3a, 3b, and 3c are translucent portions 17 formed by exposing the transparent substrate 11.

  Here, the light shielding portion 15 is a portion on the transparent substrate 11 where at least the light shielding film pattern 14a is formed, and the exposure light transmittance thereof is substantially zero. The phase shift portion 16 is a portion on the transparent substrate 11 where the phase shift film pattern 12a having a light transmittance of 6% (vs. i line) is formed, and the phase difference from the light transmission portion 17 is 180 degrees ( (I line).

  Next, the phase shift mask PSMTP (A) shown in FIG. 1C is also composed of a line-and-space pattern having a line width L of 2.0 μm and a space width S of 2.0 μm, and the line pattern is 1.0 μm. Each of the light shielding portions has a phase shift portion having a width of 0.5 μm at both edges. The space pattern is composed of a light transmitting portion where the transparent substrate is exposed. However, in the phase shift portion, the thickness of the phase shift film formed on the transparent substrate is gradually reduced to 10 steps from the light shielding portion side to the light transmitting portion side (in the width direction of the line pattern). Is formed. That is, the portion closest to the light-shielding portion has a transmittance of 6% (vs. i line) and a phase difference of 180 degrees from the light transmitting portion (vs. i line), whereas the portion closest to the light transmitting portion is The light transmittance is 57.5% (vs i line), and the phase difference from the light transmitting part (vs i line) is 20.19 degrees.

  Subsequently, the binary mask (Bin) shown in FIG. 1 (c) has a line-and-space pattern with a line width L of 2.0 μm and a space width S of 2.0 μm, and the line portion is formed on the transparent substrate with a light shielding film. The light-transmitting portion is a portion where the surface of the transparent substrate is exposed.

  FIG. 2 is a light intensity distribution curve formed on the transferred material when exposed using the above-described PSM (A), PSMTP (A), and Bin. The center of the line pattern 2a was set to the zero position. Here, the light intensity is 1.0 when the transmittance is 100%. When the maximum value (maximum light intensity) of the light intensity distribution curve is Imax and the minimum value (minimum light intensity) is Imin, the contrast can be calculated as (Imax−Imin) / (Imax + Imin).

  Table 1 below shows the numerical values of Imax, Imin, and contrast for each of the PSM (A), PSMTP (A), and Bin masks.

  From these results, in the phase shift mask (PSM (A)) in which the edge cross section of the phase shift film pattern is not tapered (the cross section is perpendicular to the substrate), the edge cross section of the phase shift film pattern is tapered. The contrast is higher than in the case of a certain phase shift mask (PSMTP (A)) or binary mask (Bin).

  As shown in Table 1 above, the contrast when PSM (A) is used is 0.67273, but according to the study by the inventors, it is desirable that a contrast of 0.65 or more is obtained. Further, it is desirable to obtain a value of 0.1 or less as the minimum value Imin.

  In PSMTP (A), the contrast is lower than that of Bin. Since the edge portion of the phase shift film pattern of PSMTP (A) is tapered, the transmittance increases as it approaches the light transmitting portion, and the phase difference from the light transmitting portion decreases. For this reason, it can be seen that, at the boundary between the phase shift portion and the light transmitting portion, the contrast improvement effect due to the interference of the light of the inverted phase is reduced.

  This means that the contrast of the light intensity distribution formed on the transferred body is deteriorated, that is, the profile (resist cross-sectional shape) of the resist pattern formed thereon is deteriorated.

  As described above, by making the cross section of the edge portion of the phase shift film pattern perpendicular to the substrate surface, the contrast improvement effect due to the interference of the light of the inverted phase at the boundary between the light transmitting portion and the phase shift portion is improved. I understand.

  Next, a method for suppressing the inclination of the edge of the phase shift film pattern at the boundary between the phase shift portion and the light transmitting portion was examined.

  Infiltration of the etchant during wet etching into the interface between the resist film (formed with the photosensitive resin composition) and the chromium-based phase shift film has sufficient adhesion between the chromium-based phase shift film and the resist film. Due to not. This not only deteriorates (inclines) the shape of the cross section to be etched of the phase shift film pattern, but also deteriorates the contrast of the light intensity of the portion, as well as the CD (line width) of the phase shift portion. It also leads to difficult control.

  In other words, the CD accuracy of the pattern can be improved by improving the cross-sectional shape of the phase shift film pattern to be etched. This enables production of a photomask for a display device capable of transferring a fine pattern, and contributes to a stable high yield of a display device manufactured using the photomask.

[Photomask for Display Device Production of the Present Invention]
The photomask for manufacturing a display device according to the present invention (hereinafter also referred to as the photomask of the present invention)
Manufacturing a display device in which a phase shift film, an etching mask film, and a light shielding film are patterned on a transparent substrate by wet etching, thereby forming a transfer pattern including a light shielding part, a phase shift part, and a light transmitting part. Photomask for
The light shielding portion is formed by laminating the phase shift film, the etching mask film, and the light shielding film in this order on the transparent substrate.
The phase shift portion is formed by forming the phase shift film or the phase shift film and the etching mask film on the transparent substrate,
The transparent portion is formed by exposing the transparent substrate surface,
The phase shift film is made of a material containing chromium,
The etching mask film is made of a material having etching resistance to the etching solution of the phase shift film,
The phase shift portion and the light transmitting portion have adjacent portions, and the phase shift portion and the light transmitting portion have a phase difference of about 180 degrees with respect to a representative wavelength of exposure light of the photomask. It has something.

  The photomask of the present invention can be manufactured by preparing a photomask blank in which a phase shift film 12, an etching mask film 13, and a light shielding film 14 are formed in this order on a transparent substrate 11 ( (See FIG. 3 below). However, other films may be interposed between these films or between any film and the transparent substrate 11 as long as the effects of the present invention are not hindered.

  In the photomask of the present invention, the phase shift film 12, the etching mask film 13, and the light shielding film 14 are formed on the transparent substrate 11 by patterning by wet etching based on a predetermined pattern design. It has a pattern.

  A typical configuration of the photomask of the present invention is the PSM (A) shown in FIG. 1B used for the above simulation (note that FIG. 1B shows a part of the photomask). Is).

  In the top view of the photomask (FIG. 1A), the light shielding portion 15 is formed by a laminated portion of the light shielding film pattern 14a and the etching mask film pattern 13a and the phase shift film pattern 12a corresponding to the light shielding film pattern 14a.

  Further, the portion of the phase shift film pattern 12a that is not covered with the light shielding film pattern 14a in the top view and is exposed (the portion in which the phase shift film pattern 12a can be seen in the top view) constitutes the phase shift portion 16.

  Further, the exposed portion of the transparent substrate 11 (the portion where the transparent substrate 11 can be seen in the top view) constitutes the light transmitting portion 17. The translucent portion 17 and the phase shift portion 16 have adjacent portions.

  The exposure light transmitted through the phase shift portion 16 is shifted in phase by about 180 degrees with respect to the exposure light transmitted through the light transmitting portion, and interferes with the exposure light transmitted through the light transmitting portion 17 and the adjacent portion. . As a result, the contrast of the light in the portion is increased, and the shape of the edge of the exposure light intensity curve becomes sharper. Therefore, the photomask of the present invention can cope with a fine pattern in display device manufacturing that has been required in recent years.

  Such a photomask of the present invention is not particularly limited as long as it has the above-described configuration, but typical embodiments of the photomask of the present invention will be described below.

<First photomask>
A cross-sectional view of the photomask of the present invention according to the first aspect is shown in the lower side of FIG. As the photomask 10a, for example, a photomask blank in which a phase shift film 12, an etching mask film 13, a light shielding film 14, and a first photoresist film 18 are formed in this order on a transparent substrate 11 shown in FIG. 3 is prepared. The phase shift film 12, the etching mask film 13, and the light shielding film 14 can be patterned.

This photomask 10a is
On the transparent substrate 11, the phase shift film 12, the etching mask film 13, and the light shielding film 14 are patterned by wet etching, so that a transfer pattern including the light shielding part 15, the phase shift part 16, and the light transmitting part 17 is formed. A display device manufacturing photomask 10a formed,
The light shielding portion 15 is formed by laminating the phase shift film 12, the etching mask film 13, and the light shielding film 14 in this order on the transparent substrate.
The phase shift unit 16 is formed by forming the phase shift film 12 on the transparent substrate,
The translucent part 17 is formed by exposing the surface of the transparent substrate 11.
The phase shift film 12 is made of a material containing chromium,
The etching mask film 13 is made of a material having etching resistance to the etching solution of the phase shift film 12;
The phase shift unit 16 and the translucent unit 17 have adjacent portions, and the phase shift unit 16 and the translucent unit 17 are substantially the same as the representative wavelength of the exposure light of the photomask 10a. It has a phase difference of 180 degrees.

  4A is a top view of the first photomask 10a, and when the photomask 10a is viewed from above, the patterned light shielding film 14 (that is, the light shielding film pattern 14a) can be seen. The portion constitutes the light shielding portion 15, the portion where the patterned phase shift film 12 (that is, the phase shift film pattern 12 a) can be seen constitutes the phase shift portion 16, the transparent substrate 11 is exposed, and the phase shift film 12 is etched. The portion that is not covered with either the mask film 13 or the light shielding film 14 constitutes the light transmitting portion 17.

  The configuration of the first photomask 10a can be as follows.

(Transparent substrate 11)
The material of the transparent substrate 11 is not particularly limited as long as it is a material having translucency with respect to the exposure light to be used. Examples thereof include synthetic quartz glass, soda lime glass, and alkali-free glass.

(Phase shift film 12)
Since the phase shift film 12 in the present invention transmits part of the exposure light, it can be said to be a semi-transparent film. It also has the effect of shifting the phase of the exposure light by a predetermined amount.

  The phase shift film 12 in the present invention is made of a material containing chromium. For example, chromium oxide (CrOx), nitride (CrNx), carbide (CrCx), oxynitride (CrOxNy), nitrided carbide (CrCxNy), oxidized carbide (CrOxCy), oxynitride carbide (CrOxNyCz), chromium fluoride It is preferable to contain any of the compounds (CrFx).

In order to obtain optical properties described later, a chromium-containing film having a chromium content of less than 50 atomic% is preferable.
The thickness of the phase shift film is preferably 800 to 1800 mm.

  A known etching solution can be used for wet etching of the phase shift film 12. For example, a mixed aqueous solution of ceric ammonium nitrate and perchloric acid can be used.

  In the first photomask 10a, the exposure light transmittance of the phase shift film 12 can be 2 to 15%, more preferably 3 to 8%. Here, the exposure light is a light source generally employed in an LCD exposure apparatus, and light including any of i-line, h-line, and g-line can be used. More preferably, light including all of these is used. . In the present application, as the exposure light transmittance, one of the above is used as a representative wavelength, and the transmittance and the phase difference (or phase shift amount) are defined.

  In the first photomask 10a, the phase shift amount of the exposure light (eg, i-line as a representative wavelength) of the phase shift film 12 is set to about 180 degrees. Here, substantially 180 degrees can be 160 degrees to 200 degrees, and preferably 170 degrees to 190 degrees.

  Further, the fluctuation range of the phase shift amount in the light from the wavelength 365 nm (i line) to 436 nm (g line) is preferably within 40 degrees, and more preferably within 30 degrees. When the fluctuation range is in such a range, the effect of setting the phase shift amount of the representative wavelength to approximately 180 degrees can be sufficiently obtained.

(Etching mask film 13)
It is important that the etching mask film 13 in the present invention is made of a material having high adhesion to the phase shift film 12 and etching selectivity with the phase shift film 12. That is, the etching mask film 13 is resistant to etching with respect to the etching solution for the phase shift film 12.

  Examples of the material of the etching mask film 13 in the present invention include aluminum (Al), cobalt (Co), tungsten (W), molybdenum (Mo), vanadium (V), titanium (Ti), manganese (Mn), and iron. (Fe), nickel (Ni), zirconium (Zr), magnesium (Mg), copper (Cu), yttrium (Y), sulfur (S), indium (In), tin (Sn), tantalum (Ta), hafnium A material containing one or more substances of (Hf), niobium (Nb), and silicon (Si) can be given.

  Specific examples of the material include nitride, oxide, carbide, oxynitride, carbonitride, oxycarbide, and oxycarbonitride of the substance.

  Among these, a material containing molybdenum (Mo), silicon (Si), tantalum (Ta), hafnium (Hf), aluminum (Al), or titanium (Ti) is preferably used.

  For example, when a titanium-containing material is used, titanium oxide, titanium nitride, or titanium oxynitride can be used. In that case, a mixed aqueous solution of potassium oxide and hydrogen peroxide can be used as an etchant used to remove the etching mask film 13 by etching.

  The material of the etching mask film 13 can also be a material containing metal silicide, that is, a material containing metal and silicon. Examples of the metal include transition metals such as molybdenum (Mo), tantalum (Ta), tungsten (W), and titanium (Ti). The metal silicide is, for example, a metal silicide nitride, a metal silicide oxide, a metal silicide carbide, a metal silicide oxynitride, a metal silicide carbonitride, a metal silicide oxycarbide, or a metal silicide oxycarbide. Nitride may be used.

  Specifically, molybdenum silicide (MoSi) nitride, oxide, carbide, oxynitride, carbonitride, oxycarbide, and oxycarbonitride, tantalum silicide (TaSi) nitride, oxide, carbide, Oxynitrides, carbonitrides, oxycarbides, and oxycarbonitrides, tungsten silicide (WSi) nitrides, oxides, carbides, oxynitrides, carbonitrides, oxycarbides, and oxycarbonitrides, and titanium Examples include silicide (TiSi) nitrides, oxides, carbides, oxynitrides, carbonitrides, oxycarbides, and oxycarbonitrides.

  As described above, as a material for forming the etching mask film 13, a material containing metal silicide can be used, and as mentioned above, a material not containing metal silicide can also be used.

  The film thickness of the etching mask film 13 can be 1 to 500 mm, more preferably 25 to 200 mm.

  The etching mask film 13 is preferably laminated in contact with the phase shift film 12 described above. The adhesiveness between the phase shift film 12 and the etching mask film 13 is higher than the adhesiveness between the phase shift film and the photoresist film in the conventional configuration, and the intrusion of the etching solution hardly occurs.

  Therefore, when the phase shift film 12 is patterned by wet etching, the surface to be etched can be brought close to the surface of the transparent substrate 11 perpendicularly. By doing in this way, the interference of the light of the inversion phase which arises in the boundary (adjacent part) of the phase shift part 16 and the translucent part 17 can fully be produced, and the contrast of light transmission intensity can be made high. This is advantageous in that the resolution and the depth of focus are advantageous, and the CD (line width) control of the final product (display device) is uniformly generated in the plane.

  The exposure light transmittance of the etching mask film 13 is not particularly limited in the first photomask 10a. For example, in the laminated state of the phase shift film 12, the etching mask film 13, and the light shielding film 14, the light shielding part 15 may have sufficient light shielding properties.

  The phase shift amount of the exposure light that the etching mask film 13 has is not limited. Therefore, the first mask is advantageous because the degree of freedom in selecting the material and film thickness of the etching mask film 13 is large.

(Light shielding film 14)
The light-shielding film 14 preferably has a sufficient light-shielding property (optical density OD3 or more) in the laminated state of the phase shift film 12 and the etching mask film 13. It is more preferable that the single light shielding film 14 has the same light shielding property. Further, the light shielding film 14 preferably has etching selectivity with the etching mask film 13. That is, it is desirable that the etching mask film 13 be resistant to the etching solution for the light shielding film 14.

  As the material of the light shielding film 14, a material containing Cr is preferably used. For example, in addition to chromium, chromium oxide (CrOx), nitride (CrNx), carbide (CrCx), oxynitride (CrOxNy), nitrided carbide (CrCxNy), oxycarbide (CrOxCy), oxynitride carbide (CrOxNyCz) It is preferable to contain any of these. Furthermore, it can be any one of chromium carbide, chromium nitride carbide, chromium oxycarbide, or chromium oxynitride carbide.

  When a material containing tantalum (Ta) is used for the etching mask film 13, molybdenum silicide can be used as the material of the light shielding film 14.

  The light shielding film 14 may be provided with an antireflection layer on the surface thereof. In that case, the antireflection layer can be any one of chromium oxide, chromium nitride, and chromium oxynitride.

  The thickness of the light shielding film 14 can be 500 to 2000 mm, more preferably 800 to 1500 mm, and still more preferably 900 to 1300 mm.

  A conventionally known etching solution for the light shielding film 14 can be used without any particular limitation. However, when the light shielding film 14 is formed of a material containing chromium, the etching solution used for the light shielding film 14 is the above-described one. This is the same as described in the phase shift film 12.

  The first photomask 10a is advantageous because it has a high chemical resistance because the entire surface exposed to the surface can be a chromium-based film.

<Second photomask>
Next, a cross-sectional view of the photomask according to the second aspect is shown on the lower side of FIG. Similarly to the photomask 10a, the photomask 10b can be manufactured, for example, by preparing a photomask blank shown in FIG. 3 and patterning the phase shift film 12, the etching mask film 13, and the light shielding film 14.

This photomask 10b
On the transparent substrate 11, the phase shift film 12, the etching mask film 13, and the light shielding film 14 are patterned by wet etching, so that a transfer pattern including the light shielding part 15, the phase shift part 16, and the light transmitting part 17 is formed. A display device manufacturing photomask formed,
The light shielding portion 15 is formed by laminating the phase shift film 12, the etching mask film 13, and the light shielding film 14 in this order on the transparent substrate.
The phase shift unit 16 is formed by forming the phase shift film 12 and the etching mask film 13 on the transparent substrate.
The translucent part 17 is formed by exposing the surface of the transparent substrate 11.
The phase shift film 12 is made of a material containing chromium,
The etching mask film 13 is made of a material having etching resistance to the etching solution of the phase shift film 12;
The phase shift unit 16 and the translucent unit 17 have adjacent portions, and the phase shift unit 16 and the translucent unit 17 are substantially the same as the representative wavelength of the exposure light of the photomask 10b. It has a phase difference of 180 degrees.

  4B is a top view of the second photomask 10b, and when the photomask 10b is viewed from above, the patterned light shielding film 14 (that is, the light shielding film pattern 14a) can be seen. The portion constitutes the light shielding portion 15, and the portion where the patterned etching mask film 13 (that is, the etching mask film pattern 13 a) can be seen (under the patterned phase shift film 12 (that is, the phase shift film pattern 12 a) exists. ) Constitutes the phase shift portion 16, and the portion where the transparent substrate 11 is exposed and is not covered with any of the phase shift film 12, the etching mask film 13 and the light shielding film 14 constitutes the light transmitting portion 17.

  Here, the difference between the second photomask 10 b and the first photomask 10 a is the configuration of the phase shift unit 16. That is, the phase shift unit 16 functions in a state where the patterned phase shift film 12 and the etching mask film 13 are laminated on the transparent substrate 11. Accordingly, in this laminated state, the phase difference (with respect to the representative wavelength) from the light transmitting portion 17 is approximately 180 degrees.

  The phase shift amount of the phase shift film 12 alone is preferably 160 to 200 °. At this time, the phase shift amount of the etching mask film 13 is preferably 1 to 50 °.

  Further, the fluctuation range of the phase shift amount at wavelengths of 365 nm (i-line) to 436 nm (g-line) in the stack is preferably within 40 degrees, more preferably within 30 degrees. When the fluctuation range is in such a range, the phase inversion effect with respect to the representative wavelength can be sufficiently obtained.

  The exposure light transmittance is also set to 2 to 15%, preferably 3 to 8% (vs. representative wavelength) in the laminated state of the phase shift unit 16.

  The exposure light transmittance of the phase shift film 12 alone is preferably 3 to 20%. The exposure light transmittance of the etching mask film 13 alone is preferably 70 to 99%.

  Except for the above-described points relating to the configuration of the phase shift unit 16, it can be the same as the first photomask 10 a.

  For each constituent film in the first and second photomasks, a sputtering method, an ion plating method, a vapor deposition method, or the like can be adopted as a film forming method. However, in terms of enhancing the interfacial adhesion between the two films. The sputtering method is preferable.

  There are no particular restrictions on the use of the photomask of the present invention described above. For example, the present invention can be suitably applied to a photomask including a line and space pattern for forming a pixel electrode of a display device as a transfer pattern.

  The line pattern of the line and space pattern preferably has a constant width light shielding portion and a constant width phase shift portion adjacent to both sides of the constant width light shielding portion.

  In the simulation model used in FIG. 1, line width L = space width S, and the width of each phase shift portion adjacent to both edges of the light shielding portions of PSM (A) and PSMTP (A) (referred to as rim width R). ) Was assumed to be R = 1 / 4L. However, the present invention is not limited to this.

  For example, the effect of the present invention is high when 4 ≦ pitch width P <6 (μm), L ≧ 1.5 (μm), and S ≦ 3.5 (μm).

  For example, in a line and space pattern having a rim of the phase shift portion 16 such as PSM (A), and a fine line and space pattern having a width P <6 (μm), a resist in the photomask manufacturing process is used. From the viewpoint of preventing pattern detachment, the width of the light-shielding portion 15 represented by (LR) is preferably 0.6 μm or more.

  Further, according to the study by the present inventors, in the case of emphasizing the high contrast at the time of transfer, it is preferable that L ≧ S in a fine line and space pattern of P <6 (μm). In the case of P <5 (μm), it became more remarkable. At this time, R ≧ 0.8 (μm) was more preferable.

  As shown in FIG. 5, the transfer pattern can be applied to a pattern including a hole pattern for forming a contact hole. The hole pattern includes a pattern in which a plurality of contact holes are arranged with a certain regularity (pitch).

  For example, the hole pattern includes a translucent portion 17 having a predetermined diameter, a phase shift portion 16 having a certain width surrounding the translucent portion 17, and a light shielding portion 15 surrounding the phase shift portion 16 (FIG. 5A to FIG. 5A). (See (d)).

  Here, the hole diameter (the length of one side in the case of a square, the length of a short side in the case of a rectangle, the diameter in the case of a circle) made of the translucent portion 17 is 1.5 to 5 (μm), The width (rim width R) of the phase shift unit 16 can be set to 0.3 ≦ R ≦ 1.5 (μm).

  The photomask of the present invention has a light shielding portion 15 in addition to the light transmitting portion 17 and the phase shift portion 16. This contributes to the effect of increasing the contrast of the light intensity distribution of the transmitted light as well as the inversion and interference effects of the light by the phase shift unit 16.

  On the other hand, on the photomask, a light shielding film can be formed outside the transfer pattern region to form a light shielding portion. Thereby, the reading accuracy of mark patterns such as alignment marks can be maintained high. That is, since the mark portion can be formed by a combination of the light transmitting portion and the light shielding portion, the contrast is high.

<Surface shape>
The photomask of the present invention or the photomask manufactured by the manufacturing method of the present invention described later can have the following configuration.

The etched surface of the phase shift film 12 is exposed at a portion of the transfer pattern where the light transmitting portion 17 and the phase shift portion 16 are adjacent to each other.
The photomask for manufacturing a display device, wherein, in a cross section of the adjacent portion, an upper side, a lower side, and a side side corresponding to the upper surface, the lower surface, and the etched surface (side surface) of the phase shift film 12 satisfy the following conditions.

(A) A straight line connecting the contact point between the upper side and the side side and the position of the side side at a height that is two-thirds lower than the film thickness of the phase shift film 12 from the upper surface, An angle formed with the upper side is within a range of 85 degrees to 120 degrees, and
(B) A first imaginary line that passes through the contact point between the upper side and the side side and is perpendicular to the main surface of the transparent substrate 11 and a height that is one tenth of the film thickness above the lower surface. The width of the second virtual line that passes through the position of the side of the transparent substrate 11 and is perpendicular to the main surface of the transparent substrate 11 is less than or equal to half the film thickness.

  6A and 6B illustrate the shape of the etched surface (side surface) of the patterned phase shift film 12 in the portion where the light transmitting portion 17 and the phase shift portion 16 are adjacent to each other in the photomask of the present invention. It is drawing for doing. Here, a cross section is shown in a state where the etching target surface of the phase shift film 12 is exposed. That is, in FIGS. 6A and 6B, the layer denoted PS is a patterned phase shift film 12, and the layer denoted QZ is the transparent substrate 11.

  Here, in the cross section of the adjacent portion, the upper side, the lower side and the side side corresponding to the upper surface, the lower surface and the etched surface of the phase shift film 12 satisfy the above two conditions (A) and (B).

  That is, the cross section of the adjacent portion is composed of an upper side, a lower side, and a side side 23 corresponding to the upper surface, the lower surface, and the etched surface of the phase shift film 12, respectively. In FIG. 6, the auxiliary line 21 indicates the position of the upper side corresponding to the upper surface of the phase shift film 12, and the auxiliary line 22 indicates the position of the lower side corresponding to the lower surface of the phase shift film 12. In this case, the angle formed between the upper side and the straight line connecting the contact point 26 between the upper side and the side side 23 and the position 27 of the side side at a height that is two-thirds lower than the film thickness (T) from the upper surface. θ (also referred to as a side surface angle) is in the range of 85 to 120 degrees. In FIG. 6, the auxiliary line 24 indicates a position where the height is lowered by two thirds of the film thickness from the upper surface of the phase shift film 12.

  Also, a first imaginary line 29 that passes through the contact point 26 between the upper side and the side side 23 and is perpendicular to the main surface of the transparent substrate 11 and a height that is one tenth of the film thickness higher than the lower surface of the phase shift film 12. The ratio (D / T) of the width (also referred to as the skirt width) D and the film thickness (T) of the second imaginary line 30 that passes through the position 28 of the side edge and is perpendicular to the main surface of the transparent substrate 11 ) Is 1/2 or less. In FIG. 6, the auxiliary line 25 indicates a position at a height that is one tenth of the film thickness from the lower surface.

  In the photomask of the present invention, the shape of the surface to be etched satisfies the above conditions. That is, the cross section of the edge portion of the patterned phase shift film 12 has a shape that is perpendicular or nearly perpendicular to the surface of the transparent substrate 11. From this, high contrast can be obtained in the light intensity distribution reaching the photoresist film as the transfer object due to the interference of the exposure light of the inverted phase at the boundary between the light transmitting portion 17 and the phase shift portion 16. Further, since the side surface angle of the edge of the phase shift portion 16 is small (close to 90 ° with respect to the surface of the transparent substrate 11), the phenomenon that the line width (CD) deviates from the design value can be suppressed, and the finer A pattern can be formed.

  In contrast, in FIG. 10 showing a cross section of a phase shift film pattern obtained by wet etching using a resist pattern as a mask with respect to a phase shift film containing chromium, a film having a side angle θ of 173 degrees and a skirt width is shown. The thickness ratio (D / T) was 5.6.

  Further, according to the study by the present inventors, the surface to be etched when a chromium phase shift film is wet-etched using a photoresist pattern as a mask has a θ of 120 degrees or less or a D / T of 1/2. It was difficult to:

[Photomask manufacturing method]
The present invention includes the following method for manufacturing a photomask for manufacturing a display device.

Manufacturing a display device in which a phase shift film, an etching mask film, and a light shielding film are patterned on a transparent substrate by wet etching, thereby forming a transfer pattern including a light shielding part, a phase shift part, and a light transmitting part. A method of manufacturing a photomask,
The light shielding portion is formed by laminating the phase shift film, the etching mask film, and the light shielding film in this order on the transparent substrate.
The phase shift portion is formed by forming the phase shift film or the phase shift film and the etching mask film on the transparent substrate,
In the method of manufacturing a photomask for manufacturing a display device in which the transparent substrate surface is exposed,
A step of preparing a photomask blank in which a phase shift film, an etching mask film, and a light shielding film are laminated in this order on the transparent substrate, and further a first photoresist film is formed;
Forming a pattern for transfer by performing predetermined patterning on the phase shift film, the etching mask film, and the light shielding film, respectively.
The patterning of the phase shift film includes a step of wet etching the phase shift film using the patterned etching mask film as a mask,
The phase shift film is made of a material containing chromium,
The etching mask film is made of a material having etching resistance to the etching solution of the phase shift film,
The phase shift portion and the light transmitting portion have adjacent portions, and the phase shift portion and the light transmitting portion have a phase difference of about 180 degrees with respect to a representative wavelength of exposure light of the photomask. A method for producing a photomask for manufacturing a display device, comprising:

  Here, in the step of preparing a photomask blank, a photomask in which a phase shift film 12, an etching mask film 13, and a light shielding film 14 are laminated on the transparent substrate 11, and a first photoresist film 18 is further formed. A blank is prepared (FIG. 3). Each film can be formed as follows, for example.

  Specifically, a phase shift film 12 containing chromium is formed on the main surface of a synthetic quartz glass transparent substrate 11 (size 330 mm × 450 mm) by sputtering (film formation step). After that, it is preferable to continuously expose the phase shift film 12 to an atmospheric gas described later (exposure step) without being exposed to the atmosphere.

  The phase shift film 12 preferably contains carbon (C) or fluorine (F) in addition to chromium. The phase shift film 12 containing these elements is considered effective because the shape of the surface to be etched is preferably controlled during wet etching.

  In the film forming process, using a sputtering target containing chromium or a chromium compound with a known apparatus, together with an inert gas, oxygen gas, nitrogen gas, nitrogen monoxide gas, nitrogen dioxide gas, carbon dioxide gas, hydrocarbon A mixed gas with an active gas containing either a system gas or a fluorine-based gas can be used. For example, a sputtering gas atmosphere containing carbon dioxide gas, hydrocarbon gas, or fluorine gas is preferable. These are effective in controlling (slowing down) the wet etching rate of the phase shift film 12.

For example, using a target made of chromium, a mixed gas of argon (Ar) gas, nitrogen (N ₂ ) gas, and carbon dioxide (CO ₂ ) gas is introduced into a sputtering chamber (not shown), and sputtering power is applied. A phase shift film 12 made of CrCON can be formed on the transparent substrate 11. It is preferable that the formed film is continuously sent to the next step in a gas atmosphere containing an active gas such as carbon dioxide gas, hydrocarbon gas, or fluorine gas without touching the atmosphere. This exposure gas atmosphere may contain inert gas (helium gas, neon gas, argon gas, krypton gas, xenon gas, etc.), and active gas includes oxygen gas, nitrogen gas, etc. May be.

  The phase shift film 12 may be composed of a single layer or a plurality of layers. In the case of being composed of a plurality of layers, the film formation step and the exposure step are performed a plurality of times.

  Next, an etching mask film 13 is formed on the phase shift film 12 by sputtering. As an example, formation of the etching mask film 13 containing MoSi will be described below.

  As a sputtering target, a sputtering gas (for example, a mixed gas of argon (Ar) gas and nitrogen monoxide (NO) gas) is introduced into a sputtering chamber in which molybdenum silicide (for example, Mo: Si = 1: 4) is disposed. By applying sputtering power, the etching mask film 13 made of MoSiON can be formed on the phase shift film 12.

  The surface reflectance of the etching mask film 13 formed in this way can be 15% or less (vs. representative wavelength).

  According to the study by the present inventors, the stack of the phase shift film 12 and the etching mask film 13 formed as described above is less than the result of the composition analysis in the depth direction by X-ray photoelectron spectroscopy (XPS). It has been found that a favorable tendency can be obtained. That is, in a region where the chromium (Cr) peak attributed to the phase shift film 12 and the silicon (Si) peak attributed to the etching mask film 13 (or molybdenum (Mo) peak) overlap (referred to as a composition gradient region), carbon The content of (C) increases stepwise or continuously toward the surface of the etching mask film 13 (in the direction away from the surface of the transparent substrate 11). Here, since carbon has a function of lowering the wet etching rate of the phase shift film 12, the shape of the surface to be etched of the phase shift film 12 is improved (the cross section of the edge portion of the phase shift film 12 is a transparent substrate). It is thought that this contributes to a shape that is perpendicular or nearly perpendicular to the surface.

  On the other hand, as the etching mask film 13, for example, a sputtering method using a titanium target is applied, and a sputtering atmosphere in which oxygen gas and nitrogen gas are introduced can be used to form a titanium oxynitride film. It is. The etching mask film 13 may be a single layer or may be composed of a plurality of layers.

  Next, a light shielding film 14 is formed on the etching mask film 13 by sputtering. The light shielding film 14 also has a function of indirectly improving the adhesion between the etching mask film 13 and the first photoresist film 18 formed on the light shielding film 14. At this time, when the light shielding film 14 is formed of a material containing chromium, for example, a sputtering target containing chromium or a chromium compound is used, together with an inert gas, oxygen gas, nitrogen gas, carbon dioxide gas, nitrogen oxide system The sputtering method is performed in a sputtering gas atmosphere composed of a mixed gas with an active gas containing at least one selected from the group consisting of a gas, a hydrocarbon-based gas, and a fluorine-based gas.

After the light shielding film 14 is formed, a first photoresist film 18 is further applied.
Thus, a photomask blank is manufactured. In the production of the photomask of the present invention, this photomask blank is prepared.

  The patterning of the phase shift film 12, the etching mask film 13, and the light shielding film 14 can include the following steps.

<Method 1 Method of FIG. 7>
FIG. 7 is a diagram showing an example of a photomask manufacturing method according to the first and second aspects of the present invention.

First, after preparing the photomask blank (FIG. 7A),
By drawing and developing on the first photoresist film 18, a first resist pattern 18a is formed (FIG. 7B),
The light-shielding film pattern 14a is formed by wet etching the light-shielding film 14 using the first resist pattern 18a as a mask (FIG. 7C),
After peeling off the first resist pattern 18a (FIG. 7D),
A second photoresist film 19 is formed on the entire surface of the transparent substrate 11 on which the light shielding film pattern 14a is formed (FIG. 7E),
By drawing and developing the second photoresist film 19, a second resist pattern 19a is formed (FIG. 7F),
The etching mask film 13 is wet-etched using the second resist pattern 19a as a mask (FIG. 7G),
The phase shift film 12 is wet-etched using the obtained etching mask film pattern 13a as a mask (FIG. 7H).
Then, when the second resist pattern 19a is peeled off, the photomask 10b of the second aspect described above is completed ((FIG. 7 (i)).

  After that, it is preferable that the etching mask film 13 is wet-etched using the formed light shielding film pattern 14a as a mask. Thereby, the photomask 10a of the first aspect described above is completed (FIG. 7 (j)).

<Production Method 2 Method of FIG. 8>
FIG. 8 is a diagram showing an example of a photomask manufacturing method according to the first and second aspects of the present invention. Here, a case where both the light shielding film 14 and the phase shift film 12 are films containing chromium is shown.

After preparing the photomask blank (FIG. 8A),
By drawing and developing on the first photoresist film 18, a first resist pattern 18a is formed (FIG. 8B),
The light-shielding film 14 is wet-etched using the first resist pattern 18a as a mask, and the etching mask film 13 and the phase shift film 12 are sequentially wet-etched to form a light-transmitting portion 17 that is an exposed portion of the transparent substrate 11. (FIG. 8 (c)),
After removing the first resist pattern 18a (FIG. 8D), a second photoresist film 19 is formed on the entire surface of the transparent substrate 11 on which the light transmitting portion 17 is formed (FIG. 8E),
By drawing and developing the second photoresist film 19, a second resist pattern 19a is formed (FIG. 8F),
The light shielding film pattern 14a is wet-etched using the second resist pattern 19a as a mask (FIG. 8G).
Then, by removing the second resist pattern 19a, the photomask 10b of the second aspect of the present invention is obtained (FIG. 8 (h)).
More preferably, after the light shielding film pattern 14a is wet etched, the etching mask film pattern 13a is wet etched using the second resist pattern 19a and the etched light shielding film pattern 14a as a mask (FIG. 8 (i)). . Thereafter, the second resist pattern 19a is removed to obtain the photomask 10a of the first aspect of the present invention (FIG. 8 (j)).

<Method 3 of FIG. 9>
FIG. 9 is a diagram showing an example of another method for manufacturing the photomask according to the first aspect of the present invention.

After preparing the photomask blank (FIG. 9A),
By drawing and developing on the first photoresist film 18, a first resist pattern 18a is formed (FIG. 9B),
Using the first resist pattern 18a as a mask, the light shielding film 14 is wet etched with a first etching solution to form a light shielding film pattern 14a (FIG. 9C).
Next, the etching mask film 13 is wet etched with a second etching solution to form an etching mask film pattern 13a (FIG. 9D),
Further, using the etching mask film pattern 13a as a mask, the phase shift film 12 is wet-etched with a first etchant, and the light-shielding film pattern 14a is side-etched (FIG. 9E),
The etching mask film pattern 13a is etched again with the second etchant using the light-shielding film pattern 14a subjected to the side etching as a mask (FIG. 9F),
Thereafter, the first resist pattern 18a is removed (FIG. 9G).

  This manufacturing method is advantageous in that drawing and development can be performed once and the influence of mutual misalignment due to a plurality of drawing processes can be reduced to zero. It is excellent that the phase shift portion 16 can be accurately formed (see FIG. 9F).

[Pattern Transfer Method and Display Device Manufacturing Method]
The present invention includes a pattern transfer method. That is, it includes a method of transferring a transfer pattern of the photomask using the above-described photomask and exposure apparatus.

  Further, a display device manufacturing method including pattern transfer using the above-described photomask and exposure apparatus is also included.

That is, the present invention
Using the step of preparing a photomask for manufacturing a display device of the present invention and an exposure device for manufacturing a display device that irradiates exposure light including i-line, h-line, and g-line, a transfer pattern included in the photomask is prepared. Exposing, and transferring the transfer pattern onto a transfer object, a pattern transfer method,
Using the step of preparing a photomask for manufacturing a display device of the present invention and an exposure device for manufacturing a display device that irradiates exposure light including i-line, h-line, and g-line, a transfer pattern included in the photomask is prepared. And a method for manufacturing a display device, the method including exposing and transferring the transfer pattern onto a transfer target.

  The exposure apparatus to be used can be a standard 1X exposure apparatus for LCD. That is, by using a light source having a wavelength range including i-line, h-line, and g-line (also referred to as a broad wavelength light source), a sufficient amount of irradiation light can be obtained. However, only light having a specific wavelength (for example, i-line) may be used by using an optical filter.

  The optical system of the exposure apparatus can have a numerical aperture NA of 0.06 to 0.10 and a coherence factor σ of 0.5 to 1.0. Such an exposure apparatus generally has a resolution limit of about 3 μm.

  Of course, the present invention can also be applied during transfer using a wider range of exposure apparatus. For example, the NA can be in the range of 0.06 to 0.14 or 0.06 to 0.15. There is also a need for a high-resolution exposure apparatus with an NA exceeding 0.08, which can be applied to these.

  As is clear from the above, the photomask of the present invention has the surface of the phase shift film to be etched more perpendicular to the transparent substrate, so that the profile of the photoresist pattern shape on the surface to be transferred obtained by exposure is obtained. It became possible to improve.

  According to the study by the present inventors, in the following photomask for manufacturing a display device manufactured using the manufacturing method 1, the boundary between the translucent portion and the phase shift portion of the transfer pattern (the etched surface of the phase shift film is exposed). Nine arbitrary locations were inspected across the surface. That is, when the side surface angle θ and the skirt width film thickness ratio D / T are measured, θ is in the range of 100 to 105 degrees, and all D / T is 0.45 or less (0.40 to 0.45). Within the range.

(Photomask according to the first aspect)
Transparent substrate: Synthetic quartz glass Size (330mm x 450mm)
Formed pattern: Line width 3 μm, space width 3 μm, phase shift part (rim width) 0.5 μm per side of the phase and space pattern phase shift film: CrOCN film thickness 1200 mm
Exposure light transmittance (vs. i-line): 6%
Phase difference (vs. i-line): 180 degree etching mask film: MoSiON film thickness 100 mm
Light-shielding film (with antireflection function layer): CrOCN / CrC / CrON film thickness 1000mm Optical density (OD) ≥ 3

2a, 2b, 2c Line pattern 3a, 3b, 3c Space pattern 10a Photomask 10b Photomask 11 Transparent substrate 12 Phase shift film 12a Phase shift film pattern 13 Etching mask film 13a Etching mask film pattern 14 Light shielding film 14a Light shielding film pattern 15 Light shielding Part 16 Phase shift part 17 Translucent part 18 First photoresist film 18a First resist pattern 19 Second photoresist film 19a Second resist pattern 101 Transparent glass substrate 102 Phase shift film pattern 103 Resist pattern

Claims (9)

Manufacturing a display device in which a phase shift film, an etching mask film, and a light shielding film are patterned on a transparent substrate by wet etching, thereby forming a transfer pattern including a light shielding part, a phase shift part, and a light transmitting part. Photomask for
The light shielding portion is formed by laminating the phase shift film, the etching mask film, and the light shielding film in this order on the transparent substrate.
The phase shift portion is formed by forming the phase shift film or the phase shift film and the etching mask film on the transparent substrate,
The transparent portion is formed by exposing the transparent substrate surface,
The phase shift film is made of a material containing chromium,
The etching mask film is made of a material having etching resistance to the etching solution of the phase shift film,
The phase shift portion and the light transmitting portion have adjacent portions, and the phase shift portion and the light transmitting portion have a phase difference of about 180 degrees with respect to a representative wavelength of exposure light of the photomask. With
Photomask for display device manufacturing.   The transfer pattern includes a line-and-space pattern, and the line pattern of the line-and-space pattern has a constant-width light shielding portion and a constant-width phase shift portion adjacent to both sides of the constant-width light shielding portion. The photomask for manufacturing a display device according to claim 1, wherein:   The transfer pattern includes a hole pattern, and the hole pattern includes a light-transmitting portion having a predetermined diameter, a phase shift portion having a constant width surrounding the light-transmitting portion, and a light-shielding portion surrounding the phase shift portion. The photomask for manufacturing a display device according to claim 1, wherein the photomask is characterized in that: The phase shift portion is formed by forming the phase shift film on the transparent substrate,
4. The display device manufacturing photomask according to claim 1, wherein the phase shift film has a phase shift of approximately 180 degrees with respect to a representative wavelength of the exposure light. 5. The phase shift portion is formed by laminating the phase shift film and the etching mask film in this order on the transparent substrate,
The lamination of the phase shift film and the etching mask film is a phase shift of approximately 180 degrees with respect to the representative wavelength of the exposure light. Photomask for manufacturing display devices. In the portion where the translucent portion and the phase shift portion are included in the transfer pattern, the etched surface of the phase shift film is exposed,
The upper side, the lower side, and the side corresponding to the upper surface, the lower surface, and the surface to be etched of the phase shift film satisfy the following conditions (A) and (B) in a cross section of the adjacent portion, respectively. The photomask for display apparatus manufacture of any one of Claims 1.
(A) A straight line connecting a contact point between the upper side and the side side and a position of the side side at a height that is two-thirds lower than the film thickness of the phase shift film from the upper surface, The angle between the upper side is in the range of 85 to 120 degrees, and
(B) a first imaginary line that passes through the contact point between the upper side and the side side and is perpendicular to the main surface of the transparent substrate, and a height that is one tenth of the film thickness above the lower surface; The width of the second virtual line passing through the position of the side and perpendicular to the main surface of the transparent substrate is less than or equal to half of the film thickness. Manufacturing a display device in which a phase shift film, an etching mask film, and a light shielding film are patterned on a transparent substrate by wet etching, thereby forming a transfer pattern including a light shielding part, a phase shift part, and a light transmitting part. A method of manufacturing a photomask,
The light shielding portion is formed by laminating the phase shift film, the etching mask film, and the light shielding film in this order on the transparent substrate.
The phase shift portion is formed by forming the phase shift film or the phase shift film and the etching mask film on the transparent substrate,
In the method of manufacturing a photomask for manufacturing a display device in which the transparent substrate surface is exposed,
A step of preparing a photomask blank in which a phase shift film, an etching mask film, and a light shielding film are laminated in this order on the transparent substrate, and further a first photoresist film is formed;
Forming a pattern for transfer by performing predetermined patterning on the phase shift film, the etching mask film, and the light shielding film, respectively.
The patterning of the phase shift film includes a step of wet etching the phase shift film using the patterned etching mask film as a mask,
The phase shift film is made of a material containing chromium,
The etching mask film is made of a material having etching resistance to the etching solution of the phase shift film,
The phase shift portion and the light transmitting portion have adjacent portions, and the phase shift portion and the light transmitting portion have a phase difference of about 180 degrees with respect to a representative wavelength of exposure light of the photomask. It is characterized by having
A method for manufacturing a photomask for manufacturing a display device. Preparing a photomask for manufacturing a display device according to claim 1;
Using a display device manufacturing exposure apparatus that irradiates exposure light including i-line, h-line, and g-line, the transfer pattern included in the photomask is exposed, and the transfer pattern is transferred onto the transfer target. A pattern transfer method. Preparing a photomask for manufacturing a display device according to claim 1;
Using a display device manufacturing exposure apparatus that irradiates exposure light including i-line, h-line, and g-line, the transfer pattern included in the photomask is exposed, and the transfer pattern is transferred onto the transfer target. The manufacturing method of a display apparatus including the process to do.