JP6391495B2 - Photomask, photomask set, photomask manufacturing method, and display device manufacturing method - Google Patents

Description

  The present invention relates to a photomask having excellent pattern positional accuracy. In particular, the present invention relates to a photomask and a photomask set that can be advantageously used as a photomask for manufacturing a display device, a photomask manufacturing method, and a display device manufacturing method using the photomask.

  In manufacturing a display device, it is known to use a pattern formation method in which a lithography process is reduced by using a photomask having three or more gradations.

  For example, in Patent Document 1, a transparent substrate, a light shielding film, and a translucent film having a transmittance adjusting function are stacked in random order, and the light shielding region in which the light shielding film is provided on the transparent substrate, and the transparent A semitransparent region in which only the semitransparent film is provided on a substrate, and a transmissive region in which neither the light-shielding film nor the semitransparent film is provided on the transparent substrate, are used for manufacturing a display device. A display device manufacturing gradation mask is described.

JP 2013-61670 A

  In manufacturing a display device, a photomask having a transfer pattern based on the design of a device to be obtained is often used. As a device, liquid crystal display devices and organic EL display devices mounted on smartphones and tablet terminals are required not only to be bright and power-saving and have a high operating speed, but also to have high image quality such as high resolution and wide viewing angle. . For this reason, there is a trend that demands for further miniaturization and higher density are generated with respect to a pattern of a photomask used for the above-described applications.

  Incidentally, an electronic device such as a display device is three-dimensionally formed by stacking a plurality of thin films (layers) on which patterns are formed. Accordingly, it is important to improve the coordinate accuracy in each of the plurality of layers and to coordinate each other's coordinates. That is, if the pattern coordinate accuracy of each layer does not satisfy a predetermined level, problems such as malfunctions occur in the completed device. Therefore, the allowable range of coordinate deviation required for each layer is becoming increasingly severe.

  For example, in a color filter applied to a liquid crystal display device, in order to realize a brighter display screen, the arrangement area of a black matrix (BM) and photo spacers (PS) such as a main photo spacer and a sub photo spacer is further increased. It is in the direction of narrowing. Further, by disposing a photo spacer on the black matrix, a color filter that is more advantageous in terms of brightness and power consumption can be manufactured. Therefore, in a transfer pattern provided in the photomask, it is necessary to improve CD (Critical Dimension: hereinafter used to mean the line width of the pattern) accuracy and position accuracy.

  As described above, in a display device such as a color filter, a plurality of photomasks are used in the manufacturing process, patterning and film formation are performed as many times as necessary, and layers having necessary functions are stacked. The alignment of the plurality of photomasks is performed with reference to the alignment marks formed on the photomask on the exposure machine. However, there is a limit to the alignment mark reading accuracy and mask placement accuracy, and it is inevitable that a deviation of about ± 1 μm will occur in the overlay of transfer patterns of different photomasks. Under these circumstances, the present inventor has found a new problem relating to the CD accuracy and position accuracy of the photomask.

  FIG. 2 schematically shows an example of two masks (mask A and mask B) each provided with a transfer pattern transferred onto the same transfer target (color filter substrate) in an overlapping manner.

  In the transfer pattern of the mask A, an extraction pattern composed of a light-transmitting portion and a semi-light-transmitting portion having a predetermined diameter is arranged surrounded by a light shielding portion. For example, the translucent portion forms a main photo spacer (hereinafter also simply referred to as a main spacer), and the semi-transparent portion forms a sub photo spacer (hereinafter also simply referred to as a sub spacer) having a height lower than that of the main spacer. Pattern. These two types of extraction patterns are portions where the light-shielding film is removed and the semi-transparent film or the transparent substrate is exposed.

  On the other hand, the transfer pattern of the mask B is formed with a line pattern composed of a light-transmitting portion having a predetermined width M. This line pattern can be, for example, a black matrix forming pattern.

  FIG. 1 shows an arrangement when the two transfer patterns are accurately superimposed on the transfer object. In FIG. 1 and FIG. 3 to be described later, the line-shaped pattern having the width M of the mask B is black for easy viewing. However, this line pattern may be a light-transmitting part or a semi-light-transmitting part formed in the light-shielding part, or may be a light-shielding part formed in the light-transmitting part. Can be selected depending on the characteristics of the photosensitive resin pattern and the photosensitive resin used when the mask is used.

  In this example, the width of the black matrix is M (μm), and the sub-spacer (diameter D2 (μm)) and the main spacer (diameter D1 (μm)) have the same octagonal shape.

  Of course, D1 and D2 do not necessarily have to be equal, and D2 <D1 or D2> D1. The shape is not necessarily an octagon, and may be a circle or other polygons.

  Here, the center of gravity of the sub-spacer and the main spacer is on a straight line, and this straight line will be described as an example located on the line center line of the black matrix to be superimposed and transferred (see the dotted line in FIG. 2). In FIG. 1, M = 24 μm and D1 = D2 = 20 μm. At this time, the gap (N) between the edge of the main spacer pattern or sub-spacer pattern and the edge of the black matrix pattern is 2 μm per side.

  The positional deviation of the main spacer pattern, sub-spacer pattern, and black matrix pattern will be described with reference to FIG. FIG. 3A shows a case where the transfer patterns of the mask A and the mask B are ideally transferred onto the transfer target, that is, when the main spacer and the sub spacer are arranged on the black matrix as designed. Indicates.

However, in reality, in the manufacturing process of the mask B, misalignment is likely to occur between the formation positions of the two types of spacer patterns (main and sub). This case is shown in FIG. That is, in manufacturing the mask A , it is necessary to form a semi-translucent part and a light-shielding part in addition to the translucent part, and a process of drawing patterns on the light-shielding film and the semi-transparent film, respectively. That is, between these two drawing processes, the photomask substrate is removed from the drawing apparatus, and a process such as development and etching of the light shielding film or the semi-transparent film is performed. At this time, it is difficult to completely match the first and second drawing positions in the entire plane.

  According to the study by the present inventors, it has been found that a positional deviation of about ± 0.3 to 0.5 μm can occur between the two drawing operations. For example, in the example shown in FIG. 3B, the center of gravity of each pattern of the main spacer and the sub-spacer is shifted by 0.5 μm in the width direction of the black matrix.

  Next, consider a case where the transfer pattern is transferred onto the transfer object using the photomask thus formed, that is, the photomask A having the transfer pattern shown in FIG. The positioning on the transfer target at this time is performed by detecting an alignment pattern formed on the photomask with an exposure apparatus. The alignment mark can be formed at an appropriate position outside the region when the transfer pattern is formed on the photomask. Accordingly, when the transfer pattern formed by the second drawing as described above is included, the alignment mark data can be included in the drawing data in the first or second drawing.

  However, there is a limit to the accuracy in the stage where the alignment mark is detected and aligned by the exposure apparatus. For this reason, even if the same exposure apparatus is used, a positional shift of a range of about ± 2.0 μm can occur in the alignment of the transfer patterns of a plurality of photomasks that are sequentially superimposed and exposed. It is in.

  Therefore, the amount of mutual displacement between a plurality of photomasks (here, photomask A and photomask B) generated by the exposure apparatus is set to 2.0 μm, and the above-described positional displacement of photomask A (± 0.5 μm) In addition, as shown in FIG. 3C, a positional shift due to the accumulation of these occurs on the transfer target. In this example, the relative displacement between the photomask A having the spacer pattern and the photomask B having the black matrix pattern on the transfer target (for example, the color filter substrate) is a result of accumulation of the displacement. As shown in FIG. 3C, a part of the main spacer protrudes from the width of the black matrix.

  Conventionally, a margin for arranging the main spacer or the sub-spacer on the black matrix (the gap N (μm) between the edge of the main spacer pattern or the sub-spacer pattern and the edge of the black matrix) is sufficiently large. Therefore, such misalignment between a plurality of layers (layers) has not been a particular problem. However, with the recent miniaturization and high integration of the mask pattern, the gap (margin) N has rapidly decreased (2.0 μm in the above example), which is an alignment shift (2. 5 μm) cannot be absorbed. Therefore, even when the gap (margin) N between the edge of the main spacer pattern or sub-spacer pattern and the edge of the black matrix is small, a part of the main spacer or sub-spacer protrudes from the width of the black matrix. In order not to cause a problem, it is a new technical problem to suppress misalignment between a plurality of layers.

  For this reason, in the manufacturing process of a photomask having a light-shielding part, a light-transmitting part, and a semi-light-transmitting part, as described in Patent Document 1, a first patterning process and a second patterning process (each including a drawing process) The present inventors paid attention to the problem that it is difficult to manufacture a high-precision display device by applying the above.

  The present invention solves the above-described problems, and provides a photomask that can be stably produced with a high yield even in a display device that is miniaturized and has a high degree of integration, and a method for manufacturing the photomask. Specifically, in the manufacturing process of the display device, even when the gap (margin) N between the edge of the main spacer pattern or sub-spacer pattern and the edge of the black matrix is small, a part of the main spacer or sub-spacer is black. An object of the present invention is to suppress misalignment between a plurality of layers (layers) so as not to cause a problem of protruding from the width of the matrix.

  In order to solve the above problems, the present invention has the following configuration. The present invention includes a photomask having the following configurations 1 to 11, a photomask set having the following configuration 12, and a photomask having the following configurations 14 to 15. A manufacturing method of a display device characterized by the following configuration 16.

(Configuration 1)
Configuration 1 of the present invention is a photomask having a transfer pattern obtained by patterning a semi-transparent film and a light-shielding film formed on a transparent substrate, and the transfer pattern includes a translucent portion and A light-shielding portion, a semi-transparent portion, and a semi-transparent rim portion, wherein the translucent portion is adjacent to the semi-transparent rim portion having a width W (μm), and the semi-transparent rim portion is A photomask that is adjacent to a light shielding portion and satisfies 0 <W ≦ 0.3.

(Configuration 2)
Configuration 2 of the present invention is the photomask according to Configuration 1, wherein the translucent rim portion is adjacent to the translucent portion from at least two symmetrical directions.

(Configuration 3)
Configuration 3 of the present invention is the photo according to Configuration 1 or 2, wherein in the transfer pattern, the semi-translucent portion is adjacent to the light shielding portion and surrounded by the light shielding portion. It is a mask.

(Configuration 4)
Configuration 4 of the present invention is the photomask according to any one of Configurations 1 to 3, wherein in the transfer pattern, the translucent portion is not adjacent to the semi-translucent portion.

(Configuration 5)
According to Configuration 5 of the present invention, in the transfer pattern, the translucent rim portion is disposed around the translucent portion, so that the translucent portion is surrounded by the translucent rim portion. The photomask according to any one of Configurations 1 to 4, wherein:

(Configuration 6)
Configuration 6 of the present invention is the photomask according to any one of Configurations 1 to 5, wherein D2 ≦ 20 when the diameter of the semi-translucent portion is D2 (μm).

(Configuration 7)
Configuration 7 of the present invention is the photomask according to any one of Configurations 1 to 6, wherein D1 ≦ 20 when the diameter of the light transmitting portion is D1 (μm).

(Configuration 8)
Configuration 8 of the present invention is the configuration 8 according to any one of the configurations 1 to 7, wherein the light-shielding portion includes a laminated body in which the semi-transparent film and the light-shielding film are stacked in this order on the transparent substrate. This is a photomask.

(Configuration 9)
The structure 9 of the present invention is characterized in that the stacked body includes a stacked body in which the semi-transparent film, the etching stopper film, and the light shielding film are stacked in this order on the transparent substrate. This is a photomask.

(Configuration 10)
The structure 10 of the present invention is the photomask according to any one of structures 1 to 9, which is a photomask for manufacturing a display device.

(Configuration 11)
The eleventh aspect of the present invention is the photomask according to the tenth aspect, which is for producing a color filter.

(Configuration 12)
Configuration 12 of the present invention includes the first photomask and a second photomask different from the first photomask when the photomask according to any one of Configurations 1 to 11 is used as the first photomask. In the photomask set, the second photomask includes a transfer pattern that is exposed to overlap with the first photomask, and the transfer pattern of the second photomask has a width M (μm) (provided that It is a photomask set including a linear pattern of 5 <M <25).

(Configuration 13)
Configuration 13 of the present invention is a transfer pattern including a translucent part, a light-shielding part, a semi-translucent part, and a semi-transparent rim part formed by patterning a semi-transparent film and a light-shielding film on a transparent substrate. A photomask manufacturing method comprising: a step of preparing a photomask blank in which the translucent film, the light-shielding film, and a resist film are laminated in this order on the transparent substrate; By applying different irradiation energy depending on the region, drawing on the resist film, and developing, a part of the light-shielding film is exposed, and the remaining film portion has a different remaining film thickness depending on the region. Forming a resist pattern; a resist pattern forming step; and a first etching step of etching the light-shielding film and the semi-transparent film using the first resist pattern as a mask; Reducing the first resist pattern to newly form a second resist pattern that exposes a part of the light shielding film; and etching the light shielding film using the second resist pattern as a mask; A second etching step, and the first etching step and the second etching step include a pattern including the translucent part, the light shielding part, the semi-translucent part, and the semi-transparent rim part. The translucent part is formed with a pattern adjacent to the light-shielding part through the semi-translucent rim part having a width W (μm), and 0 <W ≦ 0.3. And a photomask manufacturing method.

(Configuration 14)
According to the fourteenth aspect of the present invention, there is provided a transfer pattern including a translucent part, a light-shielding part, a semi-translucent part, and a semi-transparent rim part formed by patterning a semi-transparent film and a light-shielding film on a transparent substrate. A method of manufacturing a photomask, comprising: preparing a photomask blank in which the semi-transparent film, the etching stopper film, the light-shielding film, and a resist film are laminated in this order on the transparent substrate; and drawing Using the apparatus, by applying different irradiation energy depending on the region, drawing on the resist film and developing, a part of the light shielding film is exposed, and in the remaining film part, the remaining film thickness depends on the region Forming a first resist pattern having a different pattern, a resist pattern forming step, and using the first resist pattern as a mask, the light shielding film, the etching stopper film, and the front A first etching step for etching the semi-transparent film; a resist thinning step for reducing the first resist pattern to form a second resist pattern for newly exposing a part of the light shielding film; A second etching step that etches at least the light-shielding film using the resist pattern as a mask, and the light-transmitting portion, the light-shielding portion, and the semi-transmissive portion are formed by the first etching step and the second etching step. A pattern including a light part and the semi-transparent rim part, wherein the translucent part is formed with a pattern adjacent to the light shielding part via the semi-transparent rim part having a width W (μm), And it is 0 <W <= 0.3, It is a manufacturing method of the photomask characterized by the above-mentioned.

(Configuration 15)
The structure 15 of the present invention is the photomask manufacturing method according to the structure 13 or 14, characterized in that the drawing process is performed only once.

(Configuration 16)
Configuration 16 of the present invention includes the photomask according to any one of Configurations 1 to 11, the photomask set according to Configuration 12, or the transfer pattern of the photomask produced by the manufacturing method according to Configurations 13 to 15, It is a manufacturing method of a display apparatus which has the process of transferring to a transferred object using an exposure device.

  According to the present invention, it is possible to provide a photomask that can be stably manufactured with high yield and a manufacturing method thereof even in a display device that is further miniaturized and has a high degree of integration.

It is a schematic diagram showing an example of an arrangement when two transfer patterns are accurately superimposed on a transfer target. It is a schematic diagram showing an example of two masks (mask A and mask B) each provided with a transfer pattern transferred onto the same transfer target in an overlapping manner. It is a schematic diagram for demonstrating position shift of a main spacer pattern, a sub-spacer pattern, and a black matrix pattern. It is a plane schematic diagram which shows an example of the pattern for transfer of the photomask of this invention. It is a cross-sectional schematic diagram which shows the manufacturing method 1 of the photomask of this invention. It is a cross-sectional schematic diagram which shows the manufacturing method 2 of the photomask of this invention. It is a schematic diagram which shows an example of a pattern position accuracy test | inspection. It is a figure which shows the result of the propriety of the edge detection around a translucent part when changing the width W of a semi-translucent rim part. It is a figure which shows the change of a light intensity curve when changing the width W (Rim width W) of a semi-transparent rim part in the pattern shown in FIG.4 (b). It is a schematic diagram which shows an example of the manufacturing process of the conventional photomask.

  A conventional photomask, for example, a photomask described in Patent Document 1, is manufactured by the following process. FIG. 10 shows a conventional photomask manufacturing process.

  In the conventional photomask manufacturing process shown in FIG. 10, a mask blank in which a semitransparent film 3a and a light-shielding film 4a are first laminated in this order on a transparent substrate 2 is prepared (FIG. 10A). Next, a resist material is applied on the light shielding film 4a to form a first resist film 23a (FIG. 10B). Next, pattern exposure of the semitransparent film and the light shielding film is performed. Subsequently, the first resist film 23a is developed to form a first resist pattern 23b (FIG. 10C). Next, the transparent film 3a and the light shielding film 4a exposed from the first resist pattern 23b are etched to form the semitransparent film pattern 3b and the light shielding film intermediate pattern 4b (FIG. 10D). Next, the remaining first resist pattern 23b is removed (FIG. 10E). Next, a resist material is applied to form a second resist film 24a (FIG. 10F). Subsequently, the second resist pattern 24b is formed by pattern exposure of the light shielding film and development (FIG. 10G). Next, the light shielding film intermediate pattern 4b exposed from the second resist pattern 24b is etched to form a light shielding film pattern 4c (FIG. 10H). Then, the remaining second resist pattern 24b is removed to obtain a photomask (FIG. 10 (i)).

  In the above-described conventional photomask manufacturing process, it is inevitable that the formation position of the first resist pattern and the formation position of the second resist pattern are shifted from each other. This is because it is necessary to remove and remount the substrate from the drawing apparatus during the drawing process for forming each resist pattern. For this reason, for example, as shown in FIG. 10 (g2), the position of the second resist pattern 24b is deviated from the pattern formed by the first resist pattern (see the one-dot chain line in FIG. 10 (g2)). ). Therefore, in the present invention, in order to completely prevent relative displacement from occurring in the drawing process for forming the first and second resist patterns, a process for drawing all necessary patterns at one time is considered. .

<Manufacturing method 1>
FIG. 5 shows a photomask manufacturing method in which the drawing process of a photomask provided with a light-transmitting portion, a light-shielding portion, and a semi-light-transmitting portion is performed once as manufacturing method 1.

  First, as in FIG. 10, a photomask blank is prepared in which a semi-transparent film and a light-shielding film are laminated in this order on a transparent substrate, and a resist film is further formed (FIG. 5A).

  The transparent substrate is made of, for example, synthetic quartz, and both main surfaces are polished flat and smooth. The first main surface is a rectangle having a side of 300 mm to 1400 mm and a thickness of about 5 to 13 mm.

  The semi-transparent film transmits part of the exposure light when using a photomask, and its transmittance is preferably 5 to 60%, more preferably 10 when the transparent substrate is 100%. ~ 50%. This is for the representative wavelength included in the exposure light. Here, the exposure light is preferably light having a wavelength range of 365 nm (i-line) to 436 nm (g-line), and preferably a light source including all i-line, h-line, and g-line is used. To expose. The representative wavelength mentioned above can be a wavelength within the above range. For example, any one of i-line, h-line, and g-line is set as the representative wavelength.

  There is no particular limitation on the phase shift effect of the exposure light that the semi-transparent film has.

  The light-shielding film formed on the semi-transparent film does not substantially transmit exposure light. For example, the optical density OD can be 3 or more, preferably OD4 or more.

  In addition, there is no restriction | limiting in particular about the raw material of a semi-transparent film and a light shielding film, However, The thing which can be etched is preferable, The thing which can be wet-etched is especially preferable. Here, the light shielding film includes Cr as a main component, and the semi-transparent film includes molybdenum silicide. Examples of other usable materials will be described later.

  Any film can be formed by a known film forming apparatus such as a sputtering apparatus. In this manufacturing method, due to the difference in the materials of the semi-translucent film and the light-shielding film, they have etching selectivity with each other, that is, one etchant has the other and etching resistance.

  The film thickness of the semi-light-transmitting film or the light-shielding film is determined by the material to be used and the light transmittance to be obtained by the optical film. The film thickness of the semi-transparent film or the light shielding film is, for example, 20 to 2000 mm (angstrom), and particularly the light shielding film can be 1000 to 2000 mm. The film thickness of the semi-translucent film can be 20 to 500 mm.

  As the resist, a photoresist can be used. The photoresist may be either a positive type or a negative type, but in the example of this embodiment, the description will be made using a positive type. The resist film can be formed by a known coating apparatus such as a slit coater or a spin coater. The film thickness is preferably 3000 to 10,000 mm.

  Next, two types of energy intensity (here, the dose of the laser beam) for exposing the resist film during one drawing are applied. This dose change is determined based on the pattern to be obtained. For example, drawing is performed using a low dose in a region to be a semi-transparent portion and a high dose in a region to be a translucent portion (FIG. 5B).

  Raster drawing can be applied as a drawing method. At the time of drawing, drawing may be performed while changing the dose during one scan, so that the irradiation dose amount varies depending on the region. Alternatively, when the standard dose is 100%, the irradiation dose may be different depending on the region by irradiating once or plural times depending on the region while applying a lower dose. That is, it is necessary not to remove the photomask blank from the drawing apparatus between the start and end of drawing, which is referred to as one drawing in the present application.

  The drawing apparatus may be an electron beam drawing apparatus or a laser drawing apparatus, but a laser drawing apparatus is useful as a photomask for manufacturing a display device.

  Next, the resist film is developed. Since the drawing dose differs depending on the region, a resist pattern having a three-dimensional shape with a different remaining film thickness can be formed depending on the region. Since a positive resist is used here, the resist is completely eluted and removed at the portion where high dose drawing has been performed, and the transparent substrate surface is exposed. Thereby, a translucent part is formed. On the other hand, only a part of the portion where low dose drawing has been performed is eluted because the resist is not completely exposed, and a predetermined film thickness remains (thin film portion). In the undrawn portion, the resist having a film thickness close to the initial film thickness remains (thick film portion).

  Using this resist pattern as a mask, the exposed light shielding film is removed by etching, and further the semi-transparent film is removed by etching (FIG. 5C).

  As an etchant, an etchant containing ceric ammonium nitrate can be used for the Cr-based film, and an etchant containing buffered hydrofluoric acid can be used for the molybdenum silicide-based film.

  Next, the resist pattern is thinned (FIG. 5D). That is, the thickness of the resist pattern is reduced uniformly. For this purpose, a part of the resist surface may be lost by bringing a chemical solution (oxidant, etc.) or gas (plasma ashing, ozone, etc.) into contact with the resist surface, or performing additional development with a developer. The resist in the thin film portion is removed, the light shielding film is exposed at a position corresponding to the semi-translucent portion, and the thick film portion remains in a state where the film thickness is uniformly reduced (FIG. 5 ( d)).

  The light-shielding film newly exposed in the step of FIG. 5D is removed by etching to form a semi-translucent portion (FIG. 5E).

  When the remaining resist pattern is removed, a photomask provided with a three-tone transfer pattern having a light transmitting portion, a light shielding portion, and a semi-light transmitting portion is completed (FIG. 5F). The photomask of the present invention further has a semi-transparent rim portion.

  Here, the mutual positional relationship between the finally formed light-transmitting portion (corresponding to the main spacer) and the semi-light-transmitting portion (corresponding to the sub-spacer) is the same as that performed in the process shown in FIG. Determined by the drawing process. Therefore, the mutual displacement of the translucent part and the semi-translucent part does not occur.

  However, the transfer pattern formed by this manufacturing method has the following characteristics. That is, as shown in FIG. 5F, the light transmitting portion and the light shielding portion are not directly adjacent to each other, and a narrow semi-transparent rim portion is formed therebetween. That is, the translucent part is adjacent to the semi-transparent rim part, and the semi-transparent rim part is adjacent to the light shielding part. The semi-transparent rim portion is formed by forming a semi-transparent film on a transparent substrate and has a constant width of W (μm).

  This semi-transparent rim portion is formed by eroding the side surface of the resist pattern when the resist film is reduced in the steps of FIG. 5C to FIG. 5D. The width W of this semi-translucent rim portion (also simply referred to as “rim width W”) varies in the range of W> 0 depending on the film reduction method and conditions.

  As described above, the present invention is characterized in that the above three gradations can be formed by one drawing. In other words, as in the present invention, in the transfer pattern in which the semi-transparent rim portion is arranged between the translucent portion and the light-shielding portion, it is possible to completely eliminate the positional deviation in the transfer pattern. become. If a transfer pattern is designed in consideration of the presence of the semi-translucent rim portion, a photomask having excellent accuracy and suitability for the above-described applications can be provided.

  Accordingly, the present inventor has intensively studied the design of a transfer pattern including a semi-transparent rim portion.

  In the photomask manufacturing process, there is an inspection process for evaluating the quality of the transfer pattern after the transfer pattern is formed. Here, the edge position of the pattern is optically detected, and it is confirmed whether or not the pattern as designed is formed.

  FIG. 7 shows a schematic diagram of pattern position accuracy inspection performed by irradiating the pattern of FIG. 4B formed with the above-described process with inspection light. That is, the edge position of each film is detected by irradiating the transfer pattern with laser light from a coordinate measuring machine and detecting the reflected light.

  Here, it is ideal that the reflected light from each of the light shielding film, the semi-transparent film, and the transparent substrate can be received with an appropriate contrast. Actually, if the width W of the semi-translucent rim portion is sufficiently small, the edge of the light shielding film (that is, the edge of the light shielding portion) can be detected. At this time, the semi-transparent rim portion is not recognized as an independent pattern, but there is no problem because the position accuracy of the pattern can be inspected by measuring the center of gravity.

  Moreover, if the width W of the semi-transparent rim portion is sufficiently large, the edge of the light shielding film and the edge of the semi-transparent film forming the semi-transparent rim portion can be detected independently. For this reason, an accurate inspection can be performed.

  However, depending on the size of the width W of the semi-transparent rim portion, the signal indicating the edge of the light-shielding film and the signal for detecting the edge of the semi-transparent rim portion are mixed indistinguishably, and the evaluation of the inspection value is accurate. I can't do it.

  FIG. 8 shows a result of whether or not edge detection (Edge detection) around the light shielding portion is possible when the width W (Rim width W) of the semi-transparent rim portion is changed from 0.3 μm to 0.45 μm. According to the study of the present inventor, as shown in FIG. 8, the inspection is possible if the width W of the semi-transparent rim portion is set to either W ≦ 0.3 μm or W ≧ 0.45 μm. I understood.

  However, when the width W of the semi-translucent rim portion is large, the amount of light transmitted through the translucent portion is reduced, which is equivalent to partially losing the exposure amount. In the distribution of the light intensity that reaches the transfer target when the transfer pattern including the semi-transparent rim portion is exposed, the above point is not necessarily obtained from the point that an appropriate contrast is obtained with a sufficient amount of light. It is not preferable.

  Therefore, the pattern of the light-transmitting portion adjacent to and surrounded by the semi-transparent rim portion shown in FIG. 4B is exposed by an exposure device to be formed on a transfer target (for example, a color filter substrate). The light intensity distribution was obtained by simulation. The result is shown in FIG.

  As the exposure conditions, optical conditions used for an FPD exposure apparatus (here, a proximity exposure apparatus) were applied. That is, the light source wavelength includes i-line, h-line, and g-line, and the proximity gap is 100 μm.

  FIG. 9 shows changes in the light intensity curve when the width W (Rim width W) of the semi-translucent rim portion is changed between 0 and 0.5 μm in the pattern shown in FIG. 4B. As shown in FIG. 9, as the rim width W increases, the peak position of the light intensity curve decreases, and the side inclination gradually decreases. For example, when the diameter D1 is 10 μm and the rim width W exceeds 0.4 μm, the peak value of the light intensity is reduced by 10% (FIG. 9).

That is, from the viewpoint of pattern position accuracy inspection, it is desirable that the rim width W is smaller than or larger than a predetermined range. However, in consideration of a change in transferability due to loss of exposure light when using a mask, the rim width W W is preferably not too large. Therefore, the width W of the semi-transparent rim portion is
0 <W ≦ 0.3
Is most preferable.

  In order to adjust the rim width W, in the manufacturing method 1, the conditions for resist thinning are adjusted in the step shown in FIG. It is possible to select an optimum solution by adjusting the liquid agent having a film reducing action, the ashing conditions, the time, or the like, or selecting the developer and the developing time that cause the film reduction. In addition, there is a method of adjusting the thickness of a resist film to be applied in advance in order to obtain a desired rim width W, and a method of adjusting a dose at the time of drawing in order to apply a desired development time. . There is also a method of adjusting the rim width W by the etching time and the etching agent employed in the second etching step.

As described above, the photomask of the present invention is a photomask having a transfer pattern obtained by patterning the semi-transparent film and the light-shielding film formed on the transparent substrate,
The transfer pattern includes a translucent part, a light shielding part, a semi-translucent part, and a semi-translucent rim part,
The translucent part is adjacent to the semi-transparent rim part having a width W (μm), the semi-transparent rim part is adjacent to the light shielding part, and
0 <W ≦ 0.3
It is.

  The use of the photomask of the present invention is not particularly limited, but is extremely advantageous as a photomask for manufacturing a display device, particularly as a photomask for manufacturing a color filter of a display device. Therefore, the light transmissive portion corresponds to the main spacer in the color filter of the liquid crystal display device, and the semi-light transmissive portion will be described below as a mask for forming the sub-spacer.

  FIG. 4A is a schematic plan view showing an example of the transfer pattern of the photomask of the present invention. An enlarged view of the translucent part shown in FIG. 4 (a) is shown in FIG. 4 (b), and an enlarged view of the semi-transparent part is shown in FIG. 4 (c). Further, cross-sectional views of this photomask are shown in FIGS. 5 (f) and 6 (f).

  That is, in the transfer pattern of the photomask of the present invention shown in FIG. 4, the light-transmitting portion is not directly adjacent to the light-shielding portion, and the light-shielding portion is interposed via the semi-transparent rim portion having a width W (μm). Adjacent to. This semi-transparent rim portion is formed by forming a semi-transparent film on a transparent substrate and has a constant width W (μm). The rim width W satisfies 0 <W ≦ 0.3.

  Preferably, the translucent part is adjacent to and surrounded by the semi-translucent rim part. The semi-transparent rim portion is further adjacent to and surrounded by the light shielding portion. This is useful as a pattern for forming the main spacer of the color filter.

  In the pattern of FIG. 4, the translucent part is not adjacent to the semi-transparent part other than the semi-transparent rim part. That is, in the transfer pattern shown in FIG. 4, all the translucent portions are adjacent to the semi-transparent rim portion. When viewed from the semi-translucent rim portion, one edge of the width is adjacent to the translucent portion, and the other edge is adjacent to the light shielding portion. A semi-translucent rim portion is always interposed between the light transmitting portion and the light shielding portion. That is, in the transfer pattern shown in FIG. 4, the translucent rim portion is disposed around the translucent portion, so that the translucent portion is surrounded by the translucent rim portion.

  On the other hand, in the transfer pattern of FIG. 4, the semi-translucent portion is adjacent to the light shielding portion and is surrounded by the light shielding portion. This is useful as a pattern for forming the sub-spacer of the color filter.

  In the photomask shown in FIG. 4, the semi-translucent portion for forming the sub-spacer is a regular octagon with a diameter D2. And, when the diameter of the semi-translucent portion is D2 (μm), it is preferable that D2 ≦ 20. This is a dimension that is advantageous as a pattern for a display device to be miniaturized, and is a preferable dimension particularly for a display device with a brighter field of view.

In the case of a regular polygon, the diameter is the diameter of an inscribed circle or a circumscribed circle. In the case of a rectangle or an ellipse, the major axis or the minor axis can be used. When the semi-transparent portion serving as the sub-spacer is overlapped with the black matrix (BM) layer, the diameter of the sub-spacer pattern and the width direction of the black matrix is defined as the diameter D2. More preferably, the diameter D2 is
2 ≦ D2 ≦ 20
It is. More preferably,
5 ≦ D2 ≦ 12
It is. Furthermore, when the diameter of the translucent part for forming the main spacer is D1 (μm),
D1 ≦ 20
It is preferable that More preferably,
2 ≦ D1 ≦ 20
It is. More preferably,
5 ≦ D1 ≦ 12
It is.

In the present invention, the pattern shape is not necessarily limited to the shape shown in FIG. That is, in the transfer pattern shown in FIG. 4, both the translucent portion and the semi-transparent portion are regular octagons, but the shape is not limited to this. The shape of the translucent part and the semi-translucent part is, for example, a closed pattern (circular or polygonal shape) having a predetermined diameter, and is preferably a rotationally symmetric shape. Examples of the shape of the light transmitting part and the semi-light transmitting part include a regular octagon, a regular hexagon, and a square.

  Moreover, the shape and diameter of the light-transmitting part and the semi-light-transmitting part are not necessarily the same.

  In the photomask (transfer pattern) shown in FIG. 4, the translucent part is surrounded by a semi-translucent rim part having a width W (μm), and the light shielding part surrounds the outer periphery thereof. Therefore, the semi-transparent rim portion of the photomask of FIG. 4 is adjacent to the translucent portion and surrounds the translucent portion as a regular octagonal band having a width W. Further, the outer periphery of the light-shielding portion is adjacently surrounded.

The translucent rim width W (μm) is
0 <W ≦ 0.3
Is within a range of substantially constant width. That is, in consideration of the in-plane distribution of the rim width W on the mask, when the center value of the rim width W is WA (μm),
(WA−0.05) ≦ W ≦ (WA + 0.05)
Is within the range.

  Particularly, in the transfer pattern of the present invention, the translucent rim portion is adjacent to the translucent portion from at least two symmetrical directions (from both the left and right directions with respect to the central translucent portion shown in FIG. 5F). doing. Further, in the schematic plan view of FIG. 4B, the semi-transparent rim portion is adjacent to the translucent portion from eight directions. Here, when taking one of the directions (for example, the vertical direction in FIG. 4B), the widths W1 and W2 (μm) of the semi-translucent rim portion in the vertical direction are 0. It is in the range of 05 μm.

  In addition, as described above, in the photomask manufacturing process that requires a plurality of times of drawing, which is a conventional technique, such as the method described in Patent Document 1, film patterns such as a semitransparent film pattern and a light shielding film pattern Inevitable misalignment. Therefore, for example, the method described in Patent Document 1 cannot form a rim pattern having a constant rim width W as in the present invention. On the other hand, if the manufacturing method of the present invention is applied, a thin rim pattern having a constant rim width W can be precisely formed.

  In the transfer pattern shown in FIG. 4, the translucent part is not adjacent to the semi-transparent part other than the semi-transparent rim part. That is, the effect of the present invention is remarkable in a transfer pattern in which a semi-transparent portion other than the semi-transparent rim portion does not have a portion adjacent to the translucent portion. If the manufacturing method 2 described later is applied to suppress a positional shift in a pattern in which the semi-translucent part and the translucent part are adjacent, the CD accuracy tends to deteriorate in the semi-transparent part and the translucent part. is there.

  Moreover, it is preferable that each of the translucent part and the semi-translucent part is regularly arranged. In the pattern shown in FIG. 4, a plurality of light-transmitting portions and semi-light-transmitting portions are arranged with regularity in a region surrounded by a light shielding portion. Further, in this example, when the centroids of the plurality of translucent parts are connected, it goes on a straight line S1, and when the centroids of the plurality of translucent parts are connected, it goes on a straight line S2. Further, the two straight lines are the same straight line.

  Here, the straight lines S1 and S2 do not necessarily have to be on the same straight line. However, it is preferable that the distance between the straight line S1 and the straight line S2 (that is, the offset amount of the center of gravity of the semi-translucent portion with respect to the straight line connecting the centers of gravity of the translucent portions) is always a constant value. In this way, the translucent part and the semi-translucent part are regularly arranged on a narrow area, and it is easy to overlap with another photomask pattern having a certain area (for example, a black matrix layer). Become.

  The transfer pattern of the present invention can have a cross-sectional structure shown in FIG. That is, the light shielding part can be formed as a laminated body in which a semi-transparent film and a light shielding film are laminated in this order on a transparent substrate.

  In addition, the semi-transparent part and the semi-transparent rim part can have a configuration in which a semi-transparent film is formed on a transparent substrate and no light shielding film is formed. The translucent part is formed by exposing the surface of the transparent substrate.

  Therefore, in the present invention, the semi-transparent rim portion is a region having a width W sandwiched between the light-shielding portion and the translucent portion, and the semi-transparent film is formed on the transparent substrate, and the light-shielding film is not formed. It is an area. The semi-translucent portion is a region where the semi-transparent film is formed on the transparent substrate and the light-shielding film is not formed, and is a region other than the semi-transparent rim portion. Preferably, the semi-translucent portion has a width exceeding 0.5 μm.

  It should be noted that other films than the above may be present above, below, or in the middle of the present invention as long as the effects of the present invention are not impaired. For example, when the etching characteristics of the semi-transparent film and the light-shielding film are common, an etching stopper film may be interposed between the semi-transparent film and the light-shielding film. This will be described in the manufacturing method 2. .

<Manufacturing method 2>
In FIG. 6, the process of the manufacturing method 2 is shown. The difference from the manufacturing method 1 (FIG. 5) is that both the semi-light-transmitting film and the light-shielding film have common etching characteristics (for example, both contain Cr). An etching stopper film is disposed between them, and the process is changed accordingly.

  First, a semi-transparent film, an etching stopper film (ES film), and a light-shielding film are laminated in this order on a transparent substrate, and a photomask blank having a resist film is prepared (FIG. 6A). . Here, the semi-transparent film is a film containing Cr, the light shielding film is also a film containing Cr, and the etching stopper film is a film containing molybdenum silicide.

  Next, drawing is performed in the same manner as in manufacturing method 1 (FIG. 6B).

  In the same manner as in manufacturing method 1, the resist film is developed to form a resist pattern. Similar to the manufacturing method 1, a resist pattern having a three-dimensional structure, in which the remaining film thickness varies depending on the region, is formed. Thereafter, using this resist pattern as a mask, the exposed light shielding film is removed by etching, and then the etching stopper and further the semi-transparent film are removed by etching (FIG. 6C).

  Next, the resist pattern is thinned. Appropriate conditions for obtaining the width W of the semi-translucent rim portion to be formed are employed during the film reduction. Due to the reduction of the resist pattern, a part of the light shielding film is newly exposed at a position corresponding to the semi-translucent portion (FIG. 6D).

  In step (d), the newly exposed semi-transparent film is removed by etching. Preferably, the etching stopper film is also etched away after the semi-transparent film. Thereby, a semi-translucent portion is formed (FIG. 6E).

  When the remaining resist pattern is removed, a photomask provided with a three-gradation transfer pattern having a light-transmitting portion, a light-shielding portion, and a semi-light-transmitting portion is completed as in manufacturing method 1 (FIG. 6F). )).

  The photomask produced by the production method 2 differs from the production method 1 in the film material and the laminated structure. That is, the light shielding part formed here includes a laminate in which a semi-transparent film, an etching stopper film, and a light shielding film are laminated in this order on a transparent substrate. However, the shape of the transfer pattern in plan view is the same as in manufacturing method 1, and more importantly, the mutual positional relationship between the translucent part (corresponding to the main spacer) and the semi-transparent part (corresponding to the sub-spacer) is Since it is determined by one drawing process performed in the process shown in FIG. 6B, there is no mutual displacement.

  Examples of materials that can be used as photomask blank materials applied to the manufacturing methods 1 and 2 are given below.

  Examples of the material for the semi-transparent film include SiON and SOG containing silicon. In addition, metal silicide and its oxide, nitride, carbide, oxynitride, and oxynitride carbide can also be used. Examples of the metal silicide include molybdenum silicide and tantalum silicide.

  Another material for the semi-translucent film is a film containing chromium (Cr). For example, a film containing any of chromium oxide, nitride, carbide, oxynitride, and oxynitride carbide can be used. Furthermore, metals other than chromium, for example, Mo, Ta, W, Zr, Nb, Ti, or compounds thereof (oxide, nitride, carbide, oxynitride, oxynitride carbide) and the like may be used.

  Examples of the material of the light shielding film include a film containing chromium (Cr). In addition to a film made of chromium, a film containing any of chromium oxide, nitride, carbide, oxynitride, and oxynitride carbide can be used. Furthermore, an optical film made of a metal other than chromium, for example, Mo, Ta, W, Zr, Nb, Ti, or a compound thereof can also be applied. For example, a metal silicide or a material containing an oxide, nitride, carbide, oxynitride, or oxynitride carbide thereof can be used. Examples of the metal silicide include molybdenum silicide and tantalum silicide.

  In the manufacturing method 1 described above, the light-shielding film and the semi-transparent film have etching selectivity with respect to each other. For example, if Si-based is used for the semi-transparent film, Cr-based is used for the light shielding film. Or vice versa.

  On the other hand, in the manufacturing method 2, Cr system can be used for the light shielding film and the semi-transparent film, and Si system can be used for the etching stopper film.

  It is preferable that the light shielding film has an antireflection layer for suppressing light reflectance on the surface thereof. In this case, for example, a layer made of a Cr compound (oxide, nitride, carbide, etc.) can be disposed as an antireflection layer on the surface portion of the light shielding film containing Cr as a main component. This antireflection layer has a function of suppressing reflection with respect to exposure light used when using a photomask, but also has an antireflection function with respect to laser light used for drawing.

  The present invention includes a photomask set.

  For example, as described above, the photomask set of the present invention is different from the first photomask when the photomask having the transfer pattern shown in FIG. 4 is used as the first photomask. 2 is a photomask set including two photomasks. The second photomask included in the photomask set of the present invention includes a transfer pattern that is exposed while being superimposed on the first photomask. The transfer pattern of the second photomask includes a line pattern having a width M (μm) (where 5 <M <25). More preferably, 5 <M <15.

  The present invention also includes a method for manufacturing a display device, which is performed using the photomask, the photomask set, or the photomask obtained by the manufacturing method. The production method of the present invention includes a transfer step of transferring the transfer pattern of the photomask to the transfer target. As an exposure apparatus used for the transfer process, it is preferable to use an apparatus for projection exposure or proximity exposure used for FPD.

  In projection exposure, the numerical aperture (NA) of the optical system is 0.08 to 0.15 (coherence factor (σ) is 0.4 to 0.9), and at least one of i-line, h-line, and g-line. An exposure apparatus of the same magnification exposure that uses a light source containing one of the two in the exposure light can be preferably used.

  Alternatively, the present invention is extremely effective in obtaining a transfer pattern with high CD and coordinate accuracy while using proximity exposure to optimize production efficiency and cost.

  As is apparent from the above, according to the present invention, a display device or the like can be stably produced with a high yield even in a display device that is miniaturized and has a high degree of integration. In particular, in the manufacturing process of the display device, even when the gap (margin) N between the edge of the main spacer pattern or sub-spacer pattern and the edge of the black matrix is small, a part of the main spacer or sub-spacer has a width of the black matrix. It is possible to suppress misalignment between a plurality of layers (layers) so as not to cause a problem of overhanging.

Claims (12)

For manufacturing a photo spacer having a transfer pattern including a translucent part, a light-shielding part, a semi-translucent part, and a semi-transparent rim part formed by patterning a semi-transparent film and a light-shielding film on a transparent substrate, respectively . A photomask manufacturing method of
The manufacturing method of the photomask has a drawing process only once,
The method for producing the photomask comprises:
Preparing a photomask blank in which the semi-transparent film, the light-shielding film, and the resist film are laminated in this order on the transparent substrate;
Using a drawing apparatus, applying different irradiation energy depending on the region, performing the drawing step for drawing on the resist film, and developing to expose a part of the light shielding film and a remaining film portion Forming a first resist pattern in which the remaining film thickness varies depending on the region, and a resist pattern forming step;
Etching the light-shielding film and the semi-transparent film using the first resist pattern as a mask;
Reducing the first resist pattern to newly form a second resist pattern exposing a part of the light shielding film;
A second etching step of etching the light shielding film using the second resist pattern as a mask,
In the first etching step and the second etching step, the translucent portion, the light shielding portion, the semi-translucent portion, and the semi-transparent rim portion are included in the pattern. A pattern adjacent to the light shielding part is formed through the semi-transparent rim part of W (μm), and
0 <W ≦ 0.3
A method for producing a photomask, characterized in that: For manufacturing a photo spacer having a transfer pattern including a translucent part, a light-shielding part, a semi-translucent part, and a semi-transparent rim part formed by patterning a semi-transparent film and a light-shielding film on a transparent substrate, respectively . A photomask manufacturing method of
The manufacturing method of the photomask has a drawing process only once,
The method for producing the photomask comprises:
Preparing a photomask blank in which the semi-transparent film, the etching stopper film, the light shielding film, and the resist film are laminated in this order on the transparent substrate;
Using a drawing apparatus, applying different irradiation energy depending on the region, performing the drawing step for drawing on the resist film, and developing to expose a part of the light shielding film and a remaining film portion Forming a first resist pattern in which the remaining film thickness varies depending on the region, and a resist pattern forming step;
Etching the light-shielding film, the etching stopper film, and the semi-transparent film using the first resist pattern as a mask; and
Reducing the first resist pattern to newly form a second resist pattern exposing a part of the light shielding film;
A second etching step of etching at least the light-shielding film using the second resist pattern as a mask,
In the first etching step and the second etching step, the light-transmitting portion, the light-shielding portion, the semi-light-transmitting portion, and the semi-light-transmitting rim portion are included in the pattern. A pattern adjacent to the light shielding part is formed through the semi-transparent rim part of (μm), and
0 <W ≦ 0.3
A method for producing a photomask, characterized in that:   The method of manufacturing a photomask according to claim 1, wherein the translucent rim portion is adjacent to the translucent portion from at least two symmetrical directions.   4. The photomask according to claim 1, wherein in the transfer pattern, the semi-translucent portion is adjacent to the light shielding portion and surrounded by the light shielding portion. 5. Manufacturing method.   5. The method of manufacturing a photomask according to claim 1, wherein the translucent part is not adjacent to the semi-translucent part in the transfer pattern.   In the transfer pattern, the translucent rim portion is disposed around the translucent portion so that the translucent portion is surrounded by the translucent rim portion. Item 6. The method for producing a photomask according to any one of Items 1 to 5.   The photomask manufacturing method according to claim 1, wherein D2 ≦ 20 when the diameter of the semi-translucent portion is D2 (μm).   8. The method of manufacturing a photomask according to claim 1, wherein D <b> 1 ≦ 20 when the diameter of the light transmitting part is D <b> 1 (μm). 9.   9. The photomask according to claim 1, wherein the light shielding part includes a stacked body in which the semi-transparent film and the light shielding film are laminated in this order on the transparent substrate. Production method.   The said laminated body contains the laminated body which laminated | stacked the said semi-transparent film, the etching stopper film | membrane, and the said light shielding film in this order on the said transparent substrate, The any one of Claims 1-8 characterized by the above-mentioned. The manufacturing method of the photomask as described.   The process of manufacturing a 1st photomask by the manufacturing method of any one of Claims 1-10,
  Preparing a second photomask, which is a transfer pattern that is exposed by being superimposed on the first photomask, and includes a line-shaped pattern having a width M (μm) (where 5 <M <25);
A method for manufacturing a photomask set, comprising: A photomask produced by the method for producing a photomask according to any one of claims 1 to 10 , or a photomask set produced by the method for producing a photomask set according to claim 11 , and using an exposure apparatus , A method for manufacturing a display device, comprising a step of transferring a transfer pattern onto a transfer target.