JP4608882B2 - Exposure mask, method for manufacturing the same, and method for manufacturing a liquid crystal device - Google Patents

Description

  The present invention relates to a technique for forming a scattering structure that scatters reflected light by making a surface of a reflective layer rough in a reflective or transflective liquid crystal device.

  In a so-called reflective liquid crystal display device, a reflective layer having light reflectivity is formed on a plate surface of a substrate holding liquid crystal. Then, external light such as sunlight and indoor illumination light incident from the observation side is reflected on the surface of the reflective layer, and this reflected light is used for image display. In this configuration, if the surface of the reflective layer is a perfect plane, the incident light on the liquid crystal display device is specularly reflected by the surface of the reflective layer and viewed by an observer. In this case, in addition to the original display image, there is a problem that an image of a person or an object facing the display surface of the liquid crystal display device is visually recognized, making it difficult to see the display.

  In order to prevent such reflection of the background, a large number of fine protrusions and depressions (hereinafter referred to as “scattering structures”) are formed on the surface of the reflective layer. According to this configuration, reflected light on the surface of the reflective layer is appropriately scattered and emitted to the observation side, so that reflection of the background can be prevented. Patent Document 1 discloses a method for forming this scattering structure. In this method, first, a large number of fine resin pieces are formed dispersed on the plate surface of the substrate, and secondly, in order to smooth the steps between these protrusions and the plate surface of the substrate. A film body covering the protrusion is provided, and third, a reflective layer is formed so as to cover the film body.

  In addition, as a method for forming such a scattering structure, a scattering structure is formed by forming a photosensitive resin material layer on a substrate of a liquid crystal display device, and exposing and developing the layer using an exposure mask. The method is known. However, when a so-called binary mask is used, it is necessary to perform a plurality of exposures in order to form a preferable scattering structure, resulting in a high manufacturing cost. Therefore, it is effective to use a multi-tone mask in order to produce an ideal scattering structure by one exposure. An example of a multi-tone mask is described in Patent Document 2.

  In consideration of mass productivity, it is efficient to expose a plurality of units of liquid crystal display substrate at a time with a large mask used in a batch exposure machine. That is, it is effective to use a multi-tone large format mask. However, the current large format mask drawing machine has a problem in alignment accuracy, so that the multi-level large format mask is manufactured by performing multiple drawing after accurately aligning the drawing machine with the mask base material. It ’s difficult.

JP 2003-75987 A JP 2002-365784 A

  The present invention has been made in view of the above problems, and a method of manufacturing a multi-tone large-format exposure mask suitable for forming a scattering structure of a reflective film without requiring high-precision alignment and its exposure It is an object of the present invention to provide a manufacturing mask and a method for manufacturing a liquid crystal device using the exposure mask.

In one aspect of the present invention, an exposure mask manufacturing method is a method of manufacturing an exposure mask that forms a mask pattern in a processing target region of a processing target, and includes a first method of forming a light shielding layer on a substrate. A step, a second step of selectively removing the light shielding layer to form a light shielding portion outside the processing target region and the processing target region, respectively , and semi-transmission on the base material on which the light shielding portion is formed A third step of forming a layer; and a step of selectively removing the semi-transmissive layer to form a light-transmitting portion, and forming a semi-transmissive portion while leaving the semi-transmissive layer at least covering the light-shielding portion. and a fourth step, in the fourth step, the processing object said shielding portion area outside formed by removing at the same time as the semi-transparent layer and forming the light transmitting portion.

  The exposure mask can be suitably used as a mask for an electro-optical device. Specifically, the exposure mask described above is suitable for forming a scattering structure in a reflective film of an electro-optical device such as a transflective or reflective liquid crystal display device, for example. And the translucent portion, the resin material formed on the substrate is selectively removed to form a scattering structure. In this exposure mask, a light shielding layer is first formed on a light-transmitting substrate such as glass, and the light shielding layer is selectively removed to form a light shielding portion. Next, a semi-transmissive layer is formed with a semi-transmissive material on the base material on which the light-shielding portion is formed, and the semi-transmissive portion and the translucent portion are formed by selectively removing the layer. Thus, a multi-tone exposure mask having a light shielding part, a semi-transmissive part, and a light transmissive part is formed on the substrate. By forming a plurality of unit mask structures corresponding to a plurality of liquid crystal display devices on a single substrate by this method, a so-called large exposure mask can be manufactured. In a preferred example, a plurality of the mask patterns can be formed on the substrate.

  In the above manufacturing method, the portion where the semi-transmissive layer is removed by the fourth step becomes the light-transmitting portion, and the portion where the semi-transmissive layer is not removed and the portion other than the light-shielding portion is the semi-transmissive portion. Become. Note that even if the semi-transmissive portion exists on the light shielding portion, the light shielding effect is not affected, and therefore it is not necessary to remove the semi-transmissive portion on the light shielding portion.

  In one aspect of the above-described exposure mask manufacturing method, the light-shielding portion and the semi-transmissive portion correspond to a processing target region of a processing target processed using the exposure mask, and the second step includes the processing target. The light shielding portion is left outside the region, and the fourth step forms the light transmitting portion by simultaneously removing the light shielding portion and the semi-transmissive layer outside the region to be processed. According to this aspect, even when it is necessary to finally form the light shielding portion only in the processing target region, in the first step, the light shielding portion is left outside the processing target region and the semi-transmissive layer is removed. At the same time, the light shielding portion outside the processing target area is removed. Thus, when the region to be removed is drawn in the second step and the fourth step by using a laser beam, an electron beam, or the like, even if the alignment accuracy of the drawing machine is not sufficient, it is formed on the exposure mask. Since the positions of all the elements that should be determined are determined based on the positions of the drawing machine in the fourth step, it is possible to prevent a problem that the relative positions between these elements are shifted. Therefore, even when the alignment accuracy of the drawing machine cannot be ensured, it is possible to manufacture an exposure mask in which each element is accurately arranged.

  In another aspect of the above-described exposure mask manufacturing method, the second step forms a mark light-shielding portion at a predetermined position on the substrate, and the fourth step performs the mark light-shielding together with the semi-transmissive layer. The mark is formed by selectively removing the portion. In this aspect, marks such as alignment marks that are required when the exposure mask is used in a manufacturing process of a liquid crystal display device or the like are formed. In this case, in the second step, a light shielding part is formed at a position where a mark is to be formed, and in the fourth process, the light shielding part is partially removed to form a mark. Since the mark position is determined based on the position of the drawing machine in the fourth step, the relative position between the mark and the other translucent part does not shift. In another aspect of the above-described exposure mask manufacturing method, the mark light-shielding portion is formed in a wider area than the mark. Thereby, a final mark can be easily formed by removing a part thereof in the fourth step.

  In another aspect of the above-described exposure mask manufacturing method, the second step removes the light shielding layer by etching using an etchant, and the fourth step uses the same etchant as the second step. Using the etching, a part of the light shielding part and the semi-transmissive layer remaining after the second step are removed by etching. Thereby, the light shielding part is formed in a region wider than the processing target area where the light shielding part should be originally formed in the second step, and not only the semi-transmissive layer but also the light shielding part outside the processing target area is simultaneously provided in the fourth process. It can be removed.

  In another aspect of the present invention, in an exposure mask having a light-transmitting portion, a light-shielding portion, and a semi-transmissive portion that transmits light at a light transmittance lower than that of the light-transmitting portion on the base material, the light shielding is performed. The part and the semi-transmissive part are formed in a region facing the processing target region of the processing target to be processed, and the light transmitting part is formed in a region facing the outside of the processing target region. As a result, it is possible to simultaneously expose a region where the resin layer or the like of the workpiece to be completely removed, a region to be completely left, and a region to be removed to some extent by batch exposure using the exposure mask. In a preferred example, at least a part of the semi-transmissive portion can be provided on the light shielding portion.

  In one aspect of the exposure mask, the light transmitting portion is also formed in a region facing the processing target region. When the object to be processed is, for example, a substrate of a transflective liquid crystal display device, an opening may be provided in the resin layer at the position of the opening of the reflective film. By forming the portion, exposure for forming the opening can be performed simultaneously.

  Another aspect of the exposure mask includes a mark formed of the same light shielding material as the light shielding portion. If the mark is formed of the same light shielding material as the light shielding portion, the light shielding portion and the mark can be formed simultaneously in the same manufacturing process of the exposure mask.

  In another aspect of the above-described exposure mask, the light-shielding portion and the semi-transmissive portion are made of a material that can be removed by the same etching solution. Thereby, in the manufacturing process of the said exposure mask, the light-shielding part and semi-transmission part which remain | survive outside the process object area | region can be simultaneously removed on the basis of the position of the same drawing machine. Therefore, it is possible to form the processing target area provided with the light shielding portion, the semi-transmissive portion, and the translucent portion with a correct relative positional relationship.

  In another aspect of the present invention, a method for manufacturing an electro-optical device includes a step of forming a photosensitive resin material layer on a substrate, and an exposure step in which the resin material layer is collectively exposed using the exposure mask. Removing the resin material layer in a region corresponding to the light transmitting portion of the exposure mask, and providing a rough surface having fine irregularities on the resin material layer in a region corresponding to the light shielding portion and the semi-transmissive portion. A developing step to be formed.

  In the above electro-optical device manufacturing method, a scattering structure is formed in the reflective film in the transflective or reflective electro-optical device. First, a photosensitive resin material is formed on a substrate such as glass, and an exposure process is performed using the exposure mask. Preferably, in the exposure step, the exposure mask is arranged so that the light shielding portion and the semi-transmissive portion face a region corresponding to a pixel region of the electro-optical device. Since the exposure mask has a light shielding portion, a semi-transmissive portion, and a light-transmitting portion, the processing target region where the scattering structure is to be formed is partially exposed by the light-shielding portion and the semi-transmissive portion, and the outer peripheral region is a light-transmissive portion. Completely exposed. Therefore, in the subsequent development process, a scattering structure having fine unevenness is formed on the resin material in the region to be processed, and the peripheral region is flattened by removing the resin material. Note that electrode wiring, a driver IC chip, and the like are provided in the peripheral region.

  Embodiments of the present invention will be described with reference to the drawings. In the drawings shown below, the dimensions and ratios of the constituent elements are different from actual ones for convenience of explanation.

[Configuration of liquid crystal display device]
First, a liquid crystal display device in which a scattering structure is formed in a reflective film using the exposure mask of the present invention will be described.

  FIG. 1 is a cross-sectional view illustrating a configuration of a liquid crystal display device according to the present embodiment, and FIG. 2 is a perspective view illustrating a part of the liquid crystal display device in an enlarged manner. A sectional view taken along line II in FIG. 2 corresponds to FIG. As shown in these drawings, the liquid crystal display device 100 includes a first substrate 10 and a second substrate 20 arranged so as to face each other through a sealing material 34 formed in a substantially rectangular frame shape. Have. These substrates are plate-like or film-like members made of a light-transmitting material such as glass or plastic. For example, a TN (Twisted Nematic) type liquid crystal 35 is sealed in a space surrounded by both substrates and the sealing material 34. In the following, as shown in FIGS. 1 and 2, the first substrate 10 side as viewed from the liquid crystal 35 is referred to as “observation side”. That is, it means the side where an observer who visually recognizes a display image by the liquid crystal display device 100 is located. On the other hand, when viewed from the liquid crystal 35, the second substrate 20 side is referred to as “back side”. A retardation plate 311 for improving the contrast of a display image and a polarizing plate 312 for polarizing incident light are attached to the observation-side plate surface of the first substrate 10. A similar retardation plate 321 and polarizing plate 322 are attached on the rear plate (not shown in FIG. 2). Further, the second substrate 20 has a portion (hereinafter referred to as “projected portion”) 20 a that projects from the periphery of the first substrate 10. An IC chip 38 having a circuit for driving the liquid crystal display device 100 is mounted on the overhanging portion 20a by a COG (Chip On Glass) technique.

  A plurality of pixel electrodes 11 are arranged in a matrix on the surface of the first substrate 10 facing the liquid crystal 35. Each pixel electrode 11 is a substantially rectangular electrode made of a conductive material having optical transparency such as ITO (Indium Tin Oxide). A scanning line 12 extending in the Y direction is formed in the gap between the pixel electrodes 11 adjacent in the X direction. Each pixel electrode 11 is connected to the scanning line 12 via a TFD (Thin Film Diode) element 13. The TFD element 13 is a two-terminal switching element having non-linear current-voltage characteristics. The plate surface of the first substrate 10 on which these elements are formed is covered with an alignment film 14 that has been subjected to a rubbing process (not shown in FIG. 2).

  On the other hand, a plurality of data lines 27 extending in the X direction are formed on the plate surface of the second substrate 20 facing the liquid crystal 35. Each data line 27 is an electrode made of a light-transmitting conductive material such as ITO, like the pixel electrode 11, and faces the plurality of pixel electrodes 11 that are arranged in the X direction on the first substrate 10. The plate surface of the second substrate 20 on which the data lines 27 are formed is covered with an alignment film 28 similar to the alignment film 14. With this configuration, the liquid crystal 35 sandwiched between the first substrate 10 and the second substrate 20 corresponds to the voltage applied from the IC chip 38 between each pixel electrode 11 and the data line 27 opposed thereto. The orientation direction changes. As shown in FIG. 2, each of the regions (hereinafter referred to as “sub-pixels”) Gs in which the orientation direction changes is assigned one of red, green, and blue.

  On the plate surface of the second substrate 20 facing the liquid crystal 35, the base layer 21, the reflective layer 22, the color filter 24, and the insulating layer 26 are laminated in this order from the second substrate 20 side. The data line 27 and the alignment film 28 described above are formed on the surface of the insulating layer 26. The color filter 24 is a resin layer provided corresponding to each sub-pixel Gs, and is colored in the color of each sub-pixel Gs by a pigment or a dye. The sub-pixel Gs corresponding to the three color filters 24 of red, green and blue constitutes a pixel which is the minimum unit of the display image. In addition, a light shielding layer 25 is formed in the gap between the color filters 24 of each color (that is, the gap between adjacent subpixels Gs). The light shielding layer 25 is formed of a resin material in which carbon black is dispersed or a metal material having a light shielding property such as chromium, and plays a role of shielding the gap between the sub-pixels Gs. The insulating layer 26 is a film body formed so as to cover the color filter 24 and the light shielding layer 25 with various resin materials such as epoxy and acrylic. The insulating layer 26 has a role of flattening the step between the color filter 24 and the light shielding layer 25 and a role of preventing the pigment and dye of the color filter 24 from leaking into the liquid crystal 35.

  On the other hand, the foundation layer 21 is a film body provided on the plate surface of the second substrate 20 and is made of a photosensitive resin material such as acrylic or epoxy. The underlayer 21 is selectively provided only in the region surrounded by the sealing material 34 on the surface of the second substrate 20 and does not exist in the overhanging portion 20a on which the IC chip 38 is mounted. Here, under the configuration in which the base layer 21 is formed over the entire surface of the second substrate 20 including the overhanging portion 20a (that is, the configuration in which the IC chip 38 is mounted on the surface of the base layer 21), the IC chip 38 is provided. There is a problem that the base layer 21 easily peels off from the second substrate 20 together with the IC chip 38 when an external force is applied. On the other hand, as in the present embodiment, the base layer 21 is completely removed from the overhanging portion 20a (that is, a configuration in which the IC chip 38 is mounted on the second substrate 20 without the base layer 21). According to this, there is an advantage that such a problem can be avoided.

  As shown in FIGS. 1 and 2, an opening 211 that penetrates the base layer 21 in the thickness direction is provided in a portion of the base layer 21 corresponding to the vicinity of the center of each sub-pixel Gs. Yes. On the other hand, the reflective layer 22 is a thin film formed on the surface of the base layer 21 by a material having light reflectivity such as a single metal such as aluminum or silver or an alloy containing these metals as a main component. The light-transmitting portion 221 is opened to correspond to the opening 211. Accordingly, a part of each color filter 24 laminated on the base layer 21 and the reflective layer 22 reaches the surface of the second substrate 20 through the light transmitting part 221 of the reflective layer 22 and the opening 211 of the base layer 21. With the configuration described above, the light emitted from the backlight unit that has entered the second substrate 20 from the back side of the liquid crystal display device 100 is transmitted through the opening 211 of the base layer 21 and the light transmitting portion 221 of the reflective layer 22. Through the color filter 24 and the liquid crystal 35, and further through the first substrate 10 to be emitted to the observation side. In this way, transmissive display is realized by the transmitted light from the back side of the liquid crystal display device 100 to the observation side. On the other hand, outside light such as room illumination light and sunlight incident on the first substrate 10 from the observation side of the liquid crystal display device 100 passes through the liquid crystal 35 and the color filter 24 and reaches the surface of the reflective layer 22. The light is reflected from the surface and emitted from the first substrate 10 to the observation side. Thus, the reflective display is realized by the light emitted to the observation side after being reflected by the reflective layer 22.

  Here, if the surface of the reflective layer 22 is a perfect plane, the incident light from the observation side with respect to the liquid crystal display device 100 is specularly reflected on the surface of the reflective layer 22. There may be a problem that a background image opposite to the image appears in the display image. In order to solve this problem, a scattering structure for appropriately scattering the reflected light is formed on the surface of the reflective layer 22 in the present embodiment. More specifically, the surface of the base layer 21 is a rough surface having a number of fine protrusions (convex portions) or depressions (concave portions), and the surface of the reflective layer 22 formed in a thin film shape on the rough surface. In the figure, fine undulations (that is, scattering structures) reflecting the rough surface of the underlayer 21 appear.

  FIG. 3 is an enlarged cross-sectional view of a part of the surface shape of the foundation layer 21 in the present embodiment. As shown in the figure, the surface of the base layer 21 is a rough surface on which a plurality of fine protrusions 213 are formed. Alternatively, if the plane including the tops of these protrusions 213 is used as a reference, the surface of the base layer 21 can be regarded as a rough surface on which a large number of fine depressions 214 are formed. Since the reflective layer 22 is formed on the base layer 21, the surface of the reflective layer 22 is a rough surface having a concavo-convex shape reflecting the fine concavo-convex shape of the base layer 21.

[Method for manufacturing liquid crystal display device]
Next, a method for manufacturing the liquid crystal display device 100 according to the present embodiment will be described with particular attention paid to the step of forming the base layer 21 and the reflective layer 22 on the second substrate 20. FIG. 4 is a process diagram (corresponding to the cross section shown in FIG. 1) showing the configuration of elements on the second substrate 20 in each manufacturing process. First, as shown in FIG. 4A, a film body 51 to be the base layer 21 is formed on the plate surface on the second substrate 20. The film body 51 is obtained by applying a positive resin material having photosensitivity on the second substrate 20 by a method such as a spin coat method. Next, the film body 51 is dried in a reduced pressure environment and then heated (pre-baked) at a temperature in the range of 85 ° C. to 105 ° C.

  Thereafter, as shown in FIG. 4B, the film body 51 is exposed through a mask (hereinafter referred to as “exposure mask”) 70. More specifically, after an exposure mask 70 is arranged with a gap (proximity gap) of about 60 μm from the surface of the film body 51, emitted light (for example, i-line) from the light source to the film body 51 ) Is irradiated. As shown in FIG. 4B, in the present embodiment, a region (that is, the sealing material 34) around the region (hereinafter referred to as “processing target region”) 511 of the film body 51 to be left as a base layer. 513, a region 515 corresponding to the opening 211 of the base layer 21, and a region to be the depression 214 on the surface of the base layer 21 in the processing target region 511. Are exposed together. The specific configuration of the exposure mask 70 used in this exposure step will be described in detail later.

  Next, the film body 51 is developed. By this development, as shown in FIG. 4C, a portion of the film body 51 that has been photolyzed by exposure is selectively removed. Subsequently, the film body 51 is heated (melt-baked) at a temperature in the range of 120 ° C. to 130 ° C. By this step, only the surface layer portion of the film body 51 is partially melted, and the uneven corners appearing on the surface of the film body 51 by development are rounded. Thereafter, the film body 51 is baked (post-baked) at a temperature of about 220 ° C. By these steps, as shown in FIG. 4D, the surface shape of the entire film body 51 is determined, and the base layer 21 is obtained. Here, the heating of the film body 51 after the development is performed in two stages. If the film body 51 after the development is immediately heated to a temperature of about 220 ° C., the unevenness on the surface thereof is excessively melted. This is because the surface has many flat portions, and as a result, the light scattering effect is impaired. That is, it can be said that the step of heating the film body 51 in the range of 120 ° C. to 130 ° C. prior to post-baking is a process for maintaining and stabilizing the surface shape of the film body 51 in an intended shape.

  Next, as illustrated in FIG. 4E, the reflective layer 22 having the light transmitting portion 221 is formed on the surface of the base layer 21. That is, a thin film made of a light-reflective material is formed on the surface of the base layer 21 by a film formation method such as sputtering, and the thin film is patterned by a photolithography technique and an etching technique to obtain the reflection layer 22. . As described above, a scattering structure reflecting the rough surface of the base layer 21 is formed on the surface of the reflective layer 22.

  Subsequently, the color filter 24 and the light shielding layer 25 are formed, and the insulating layer 26 is formed so as to cover them. Further, after the data line 27 is formed on the surface of the insulating layer 26, an alignment film 28 is formed by an organic thin film such as polyimide and subjected to a rubbing process. Meanwhile, each element on the first substrate 10 can be manufactured by various known techniques. Next, the first substrate 10 and the second substrate 20 that have undergone the above-described processes are bonded together with the sealing material 34 in a state where the alignment films 14 and 28 face each other. Further, a liquid crystal 35 is sealed in a space surrounded by both substrates and the sealing material 34, and this space is sealed with a sealing material (not shown). Thereafter, the retardation plates 311 and 321 and the polarizing plates 312 and 322 are attached to the first substrate 10 and the second substrate 20, respectively, and the IC chip 38 is mounted on the overhanging portion 20a of the second substrate 20, The liquid crystal display device 100 shown in FIG. 1 is obtained.

[Configuration of exposure mask]
Next, the configuration of the exposure mask 70 used in the exposure process of FIG. 4B (hereinafter simply referred to as “exposure process”) will be described. 5 is a plan view of the exposure mask 70, FIG. 5 (a) is a plan view in a completed state, and FIG. 5 (b) is a plan view in the middle of manufacture.

  First, the configuration of the exposure mask 70 in a completed state will be described with reference to FIG. As shown in the drawing, the exposure mask 70 is a so-called large format mask and corresponds to a plurality of liquid crystal display devices. In FIG. 5, the unit mask structure 80 corresponding to each liquid crystal display device is indicated by a broken line. Note that the unit mask structure 80 is illustrated for convenience of explanation for the portion corresponding to one liquid crystal display device 100, and lines and boundaries corresponding to the unit mask structure 80 are actually formed on the exposure mask 70. I don't mean.

  The exposure mask 70 is disposed to face a large glass substrate (not shown) corresponding to a plurality of liquid crystal display devices aligned in the vertical and horizontal directions. That is, as described in the above-described method for manufacturing a liquid crystal display device, a base layer 21 is formed of a photosensitive resin material on a single large glass substrate, and a large exposure mask 70 is disposed opposite thereto. Then, exposure for forming the scattering structure of the underlayer 21 is performed.

  A processing target region 511 exists inside each unit mask structure 80. The processing target region 511 is a region corresponding to a region where the scattering structure of the base layer 21 is to be formed on the liquid crystal display device 100 side, that is, a display region (region where pixels are formed) of the liquid crystal display device 100.

  A plurality of marks 84 are formed outside the plurality of unit mask structures 80 on the exposure mask 70. The mark 84 is an alignment mark for positioning the exposure mask 70 with respect to the large-sized glass substrate mainly during the manufacturing process of the liquid crystal display device 100, and is necessary during the manufacturing process of the liquid crystal display device 100. Marks for applications other than alignment marks may be included.

  FIG. 6 is a cross-sectional view showing the correspondence between a part of the exposure mask 70 and the scattering structure of the underlayer 21 on the liquid crystal display device 100 side formed correspondingly. That is, FIG. 6 shows a state where the exposure mask 70 is disposed opposite to the large glass substrate to expose the underlying layer 21 that is a photosensitive resin material layer. However, FIG. 6 shows a part of one liquid crystal display device 100, and the exposure mask 70 side is a part of the unit mask structure 80 shown in FIG.

  As described above, the scattering structure is formed on the base layer 21 made of the resin material on the second substrate 20 of the liquid crystal display device 100. In addition, an opening 211 is provided in each sub-pixel Gs. On the other hand, the exposure mask 70 is formed on a translucent base material 72 such as glass, and includes a light shielding portion 74, a semi-transmissive portion 76, and a translucent portion 78. The light shielding portion 74 is made of a light shielding material, and for example, two layers of chromium (Cr) and chromium oxide (CrOx) are suitable. In this case, chromium functions as a light shielding layer, and chromium oxide functions as a low reflection layer. The semi-transmissive layer 76 is made of a semi-transmissive material, and for example, chromium oxide is suitable. In the translucent part 78, no other layer is formed, and the translucent base material 78 is exposed. The translucent part 78 includes a translucent part 78 a corresponding to the peripheral region 513 described above and a translucent part 78 b corresponding to the opening 211 of the base layer 21.

  The light-shielding part 74 and the semi-transmissive part 76 are disposed so as to face a region in the processing target region 511 of the liquid crystal display device 100 where a scattering structure is to be formed in the base layer 21. On the other hand, the translucent portion 78 is disposed opposite to the peripheral region 513 outside the processing target region 511 of the liquid crystal display device 100 and the region 511 corresponding to the opening 211 of the base layer in the processing target region 511 (see FIG. 4). reference).

  When light 65 is irradiated from the back side of the exposure mask 70 during exposure, the light is completely blocked by the light shielding portion 74 and the light is completely transmitted by the light transmitting portion 78. The semi-transmissive portion 76 transmits light with a light transmittance lower than that of the light-transmissive portion 78. Therefore, as described in the column of the manufacturing method of the liquid crystal display device 100, the base layer 21 is formed on the substrate 20 with a resin material made of a positive photosensitive material, and is developed after being exposed with the exposure mask 70. As a result, in the region corresponding to the light shielding portion 74 and the semi-transmissive portion 76 of the exposure mask 70, the base layer 21 is partially removed to form a scattering structure. On the other hand, the underlying layer 21 is completely removed in the region corresponding to the light transmitting portion 78 of the exposure mask 70. Thus, as shown in FIGS. 4 and 6, in the peripheral region 513 outside the processing target region 511 on the second substrate 20 side, and in the region 515 corresponding to the opening 211 of the base layer 21 in the processing target region 511, The formation 21 is removed. In addition, a scattering structure having fine irregularities is formed in a region other than the opening 211 of the base layer 21 in the processing target region 511.

[Exposure Mask Manufacturing Method]
Next, a method for manufacturing the above-described exposure mask 70 will be described with reference to FIGS. FIGS. 7A to 7C are enlarged views of the unit mask structure 80 shown in FIG. 5, and show states in each manufacturing process of the exposure mask 70. FIGS. 7D to 7F show states in each manufacturing process of the mark 84 provided on the exposure mask 70. 8A is an enlarged view of the region A1 of the unit mask structure 80 shown in FIGS. 7A to 7C, and FIGS. 8B and 8C are X- It is sectional drawing of a X 'cross section and a YY' cross section. 9A shows a manufacturing process of the exposure mask 70, and FIGS. 9B and 9C show the XX ′ section and the YY ′ section in FIG. 8A in each process. Each layer structure is shown.

  First, with reference to FIGS. 9A and 9B, the entire manufacturing process of the exposure mask 70 will be described. The manufacture of the exposure mask 70 is basically performed by a two-stage film formation process. The first film-forming process is a process of forming the light-shielding part 74 with a light-shielding material, and the second film-forming process is a process of forming the translucent part 76 and the translucent part 78 with a semi-transmissive material.

  The process will be described below with reference to the process diagram of FIG. 9A and the X-X ′ cross-sectional view of the region A1 of the unit mask structure 82 shown in FIG. As shown in FIG. 8A, the XX ′ cross section includes a light transmitting portion 78a corresponding to the peripheral region 513, a light transmitting portion 78b corresponding to the opening 211 of the base layer 21, and three light shielding portions. Part 74a-74c is included.

  First, a light shielding layer 74x of chromium and chromium oxide is formed by sputtering on the entire surface of a translucent substrate 72 such as glass (step S1). Next, the light shielding layer 74x is partially removed to form a plurality of light shielding portions 74a to 74c (step S2). Specifically, a resist is applied on the light shielding layer 74x, and writing is performed on the resist corresponding to the pattern of the light shielding portion by a laser beam or an electron beam (hereinafter referred to as “beam”). Then, etching is performed using an etching solution corresponding to the material of the light shielding layer, whereby the light shielding layer is partially removed to form a plurality of light shielding portions 74a to 74c. When a positive resist is applied, a region other than the light shielding portions 74a to 74c is drawn with a beam, and the drawn region is removed by subsequent etching to leave the light shielding portions 74a to 74c. On the other hand, when a negative resist is applied, the regions of the light shielding portions 74a to 74c are drawn with a beam, and the regions not drawn are removed by subsequent etching to leave the regions of the light shielding portions 74a to 74c. Thus, the first film formation process is completed.

  Next, a semi-transmissive layer 76x of chromium oxide is formed by sputtering on the entire surface of the base material 72 on which the light shielding portions 74a to 74c are formed (step S3). And a resist is apply | coated on the semi-transmissive layer 7, and it draws with a beam. At this time, the regions of the translucent portions 78a and 78b are removed, drawing is performed so as to leave other regions, and then etching is performed. Thereby, the translucent layers 76x are removed from the translucent portions 78a and 78b. Since the semi-transmissive layer 76x is removed only by the light-transmitting portions 78a and 78b, the semi-transmissive layer 76x remains on the light-shielding portions 74a to 74c. Is blocked by the light blocking portions 74a to 74c, it is not necessary to remove the semi-transmissive layer 76x on the light blocking portions 74a to 74c.

  In this way, the multi-tone exposure mask 70 having the light shielding portion 74, the semi-transmissive portion 76, and the light transmissive portion 78 is manufactured by two film forming steps. The Y-Y ′ cross section shown in FIG. 9C is basically formed in the same manner. However, as shown in FIG. 8A, the YY ′ cross section does not include the light transmitting portion 78 b corresponding to the opening 211 of the base layer 21, and includes only the light transmitting portion 78 a corresponding to the peripheral region 513. It is.

  Next, a region where film formation is performed in the above-described exposure mask manufacturing process will be described with reference to FIGS. FIGS. 7A to 7C show states in each process of the unit mask structure 80 shown in FIG. FIG. 7A shows a state in which a plurality of light shielding portions 74 are formed in step S2, FIG. 7B shows a state in which a semi-transmissive film 76x is formed in step S3, and FIG. The state where the semipermeable membrane 76x is removed is shown. For convenience of explanation, the light transmitting portion 78b corresponding to the opening 211 of the base layer 21 is not shown.

  As described above, in step S <b> 2, the light shielding layer 74 x formed on the entire surface of the base material 72 is selectively removed to form a plurality of light shielding portions 74. The part to be left as the light shielding part 74 and the part to be removed are defined by the drawing in step S2. Here, since the light shielding portion 74 is a portion necessary for forming a scattering structure in the base layer 21, the light shielding portion 74 is originally left only in the processing target region 511 and does not need to be left in the peripheral region 513. However, in the present invention, in step S2, drawing is performed so that the light shielding portion 74 is left in a region 520 wider than the processing target region 511 where the light shielding portion 74 should finally be left, and the light shielding layer 74 is removed in an outer region. I do. The state of the exposure mask 70 at this time is shown in FIG. As can be seen from comparison with FIG. 5A, the light shielding portion 74 is formed over a region 520 wider than the processing target region 511.

  Then, in step S3, a semi-transmissive layer 76x is formed on the entire surface (see FIG. 7B), and at the same time as removing the semi-transmissive layer 76x in step S4, the light-shielding portion 74 existing outside the original processing target region 511. Also remove. In this way, in the finally completed exposure mask (see FIG. 7C), the light shielding portion 74 remains only in the processing target region 511.

  Thus, in the method for manufacturing an exposure mask according to the present invention, in the first film forming process, that is, in the formation process of the light shielding part, the light shielding part is left in an area wider than the processing target area 511 where the light shielding part should finally be left, The processing target region 511 is simultaneously defined in the second film forming step, that is, the step of defining the semi-transmissive portion 76 and the light transmitting portion 78. The reason for this is that there is a limit to the alignment accuracy of the drawing machine when drawing is performed a plurality of times in the manufacture of a large exposure mask. That is, if drawing is performed up to the outer edge of the processing target area 511 in the first film formation step (ie, step S2) and all the light shielding film outside the processing target area 511 is removed, the position of the light shielding portion 74 is the first time. It is defined based on the position of the drawing machine in the film forming process. Then, in the second film formation step (ie, step S4), the semi-transmissive film 76x is removed to define the semi-transmissive portion 76 and the light-transmissive portion 78. Then, when the alignment accuracy of the drawing machine cannot be ensured by the first film formation step and the second film formation step, the light shielding unit 74, the semi-transmission unit 76, and the light transmission unit 78 (particularly the light transmission unit 78) Deviation occurs in the relative position.

  Therefore, in the exposure mask manufacturing method of the present invention, the light shielding portion 74 is left in the region 520 wider than the original processing target region 511 in the first film forming step, and the processing target is processed in the second film forming step. Only the light shielding portion 74 in the region 511 is left (that is, the light shielding portion 74 outside the processing target region 511 is removed simultaneously with the semi-transmissive film). In this way, the formation region of the light-shielding portion 74 corresponding to the processing target region 511, the semi-transmissive portion 76, and the light-transmissive portion 78 are all determined depending on the position of the second drawing machine. It is possible to prevent relative displacement of the position of the region. Therefore, even when the alignment accuracy of the drawing machine in the exposure mask manufacturing machine is not sufficient, it is possible to manufacture the exposure mask 70 in which the light shielding portion 74, the semi-transmissive portion 76, and the light transmitting portion 78 are accurately formed. Therefore, in the method for manufacturing an exposure mask according to the present invention, the light-shielding portion 74 left outside the original processing target region 511 in the first film formation step S2 needs to be removed in the second film formation step S4. It is necessary that the light-shielding material constituting the light-shielding layer 74x and the semi-transmissive material constituting the semi-transmissive layer 76x can be removed with the same etching solution. For this reason, in this embodiment, chromium and chromium oxide are used as the material of the light shielding portion 74, and chromium oxide is used as the material of the semi-transmissive portion 76. However, the material of the light-shielding portion and the semi-transmissive portion is not limited to the above example as long as the material can be removed using the same etching solution in the second film formation step.

  Although the relationship between the processing target region 511 and the light shielding portion 74 has been described so far, the light transmitting portion 78b corresponding to the opening 211 of the base layer 21 is formed in the same manner. That is, in the first film forming step S2, the light shielding portion 74 is formed within the original light transmitting portion 78b (see FIG. 8A), and in the second film forming step S4, the original light transmitting portion 78b is formed. What is necessary is just to remove the light-shielding part 74 which exists inside. Thereby, the position of the translucent part 78b does not shift relative to the semi-transmissive film 76 and the translucent part 78a.

  Next, a method for forming the mark 84 will be described. As shown in FIG. 5A, the mark 84 is mainly used as an alignment mark used in manufacturing a liquid crystal display device using an exposure mask, and a plurality of marks 84 are formed on the side of the exposure mask 70. The In this example, the mark 84 has a substantially cross shape, but may have other shapes.

  7D to 7F show a method of forming the upper right mark 84 in FIG. The marks 84 are also formed simultaneously in the exposure mask manufacturing steps S1 to S4 described with reference to FIG. FIG. 7D shows the state after step S2, FIG. 7E shows the state after step S3, and FIG. 7F shows the state after step S4.

  First, after the light shielding layer 74x is formed on the entire surface of the base material 72 in step S1, the light shielding layer 74x is left in the rectangular region 84a as shown in FIG. 7D in step S2. The rectangular area 84a needs to be wider than the mark 84 to be finally formed.

  Next, when the semi-transmissive layer 76x is formed on the entire surface of the substrate 72 in step S3, the region 84a is covered with the semi-transmissive layer 76x as shown in FIG. Next, when drawing is performed in order to remove the semi-transmissive layer 76x in step S4, the four corners of the rectangular region 84a are removed, and drawing is performed so that a cross-shaped mark remains as shown in FIG. Do.

  As described above, also in the formation of the mark 84, the light shielding layer 74x is left in a wider range than the mark 84 to be finally formed in the first film formation step S2, and the final film formation step S4 is performed. The shape of the mark 84 is drawn. As described above, when the alignment accuracy of the drawing machine is insufficient, if the mark 84 is formed in the first film forming step S2, an error generated in the alignment of the drawing machine in the second film forming step is caused. This is reflected in the position of the mark 84 on the exposure mask, and an error occurs in the relative position between the light shielding portion 74 and the light transmitting portion 78 and the mark 84. Therefore, the mark 84 is formed in the second film forming step, and the mark 84 is formed together with the light shielding portion 74 and the light transmitting portion 78 on the basis of the position of the second drawing machine. Therefore, also in the formation of the mark 84, it is necessary that the light shielding layer 74x and the semi-transmissive layer 76x can be removed by the same etching solution in the same process.

[Modification]
The embodiments described above are merely examples, and various modifications can be made without departing from the spirit of the present invention. Specifically, the following modifications can be considered.

  In the above embodiment, as illustrated in FIG. 8A, the configuration in which the opening 211 is provided in the base layer 21 so as to correspond to each pixel is illustrated, but the opening 211 is not provided in the base layer 21. Configurations can also be employed. A part of the unit mask structure 80 of the exposure mask 70 in this case (corresponding to FIG. 8A) is shown in FIG. However, in this case, part of the light traveling from the second substrate 20 side to the first substrate 10 side is absorbed by the base layer 21 in the transmissive display.

  In the above-described embodiment, the opening 211 of the base layer 21 is provided in the center of each subpixel Gs independently for each subpixel Gs. Instead, the opening 211 is provided in stripes at both ends or the center of each subpixel. Also good. FIG. 10B shows an example in which openings are provided at both ends of the sub-pixel Gs. FIG. 10B also shows a part of the unit mask structure 80 of the exposure mask 70 (corresponding to FIG. 8A).

  In each of the above embodiments, the so-called transflective liquid crystal display device 100 capable of both reflective display and transmissive display has been exemplified. However, the present invention also applies to the liquid crystal display device 100 capable of only reflective display. Can be applied. In this case, the opening 211 of the reflective layer 22 and the light transmitting part 221 of the reflective layer 22 are not provided. Therefore, the light-transmitting portion 78 b corresponding to the opening 211 of the underlayer 21 is not provided in the exposure mask 70.

In each of the above embodiments, the light-shielding portion 74 is composed of two layers of chromium and chromium oxide, but it may be a chromium layer alone.
In the above embodiment, the planar shape of the light shielding portion 74 of the exposure mask 70 is a polygon, but the planar shape of the light shielding portion 74 is arbitrary, and may be, for example, a polygon other than a regular polygon or a circle.

  In the above-described embodiment, the example in which the exposure mask according to the present invention is used for forming irregularities on the surface of the base layer 21 of the liquid crystal display device 100 has been shown. It can be used for the purpose of producing irregularities for various materials.

  In the above embodiment, the present invention is applied to the liquid crystal display device 100 as an example of an electro-optical device. For example, an electroluminescence device, an organic electroluminescence device, a plasma display device, an electrophoretic display device, a field emission display ( The present invention can be similarly applied to various electro-optical devices such as field emission display devices.

It is sectional drawing which shows the structure of the liquid crystal display device manufactured by applying this invention. It is a perspective view which expands and shows the structure of the principal part of a liquid crystal display device. It is sectional drawing which shows the shape of a base layer and a reflecting film among liquid crystal display devices. It is sectional drawing which shows the manufacturing process of each element on a 2nd board | substrate among liquid crystal display devices. It is a top view of the mask for exposure which concerns on this invention. It is a figure which shows the correspondence of each layer of the mask for exposure, and the base layer of a liquid crystal display device. A unit mask structure of an exposure mask and a manufacturing process of a mark are shown. It is the enlarged view and sectional drawing of a part of unit mask structure of an exposure mask. It is a manufacturing process figure of the mask for exposure, and sectional drawing of a part of mask for exposure. It is an enlarged view of the mask structure for exposure corresponding to the other example of a liquid crystal display device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Liquid crystal display device, 10 ... 1st board | substrate, 11 ... Pixel electrode, 12 ... Scan line, 13 ... TFD element, 14 ... Alignment film, 20 ... 2nd board | substrate, 21 ... Underlayer, 211 ... Opening part, 22 ... Reflective layer, 221 ... translucent portion, 24 ... color filter, 25 ... light shielding layer, 26 ... insulating layer, 27 ... data line, 34 ... sealing material, 35 ... liquid crystal, 38 ... IC chip, 51 ... film body, 511 ... Processing target area, 513 ... peripheral area, 70 ... exposure mask, 72 ... base material, 74 ... light-shielding part, 76 ... transflective part, 78 ... translucent part

Claims (5)

A method for manufacturing an exposure mask for forming a mask pattern in a processing target region of a processing target,
A first step of forming a light shielding layer on the substrate;
A second step of selectively removing the light shielding layer and forming a light shielding portion outside the processing target region and the processing target region ;
A third step of forming a semi-transmissive layer on the base material on which the light shielding portion is formed;
A fourth step of selectively removing the semi-transmissive layer to form a light-transmitting portion and leaving the semi-transmissive layer to cover at least the light-shielding portion to form a semi-transmissive portion;
Wherein in the fourth step, the manufacturing method of the exposure mask, and forming the processing object said shielding portion area outside formed by removing at the same time as the semi-transparent layer the light-transmitting portion. In the second step , a mark light-shielding portion is formed at a predetermined position outside the processing target area on the base material,
2. The method of manufacturing an exposure mask according to claim 1 , wherein, in the fourth step , the mark is formed by selectively removing the mark light-shielding portion together with the semi-transmissive layer. 3. The method of manufacturing an exposure mask according to claim 2 , wherein the mark light-shielding portion is formed in a wider area than the mark. The said mask pattern is formed in multiple numbers on the said base material, The manufacturing method of the mask for exposure as described in any one of Claim 1 thru | or 3 characterized by the above-mentioned. In the second step , the light-shielding layer is removed by etching using an etching solution, and in the fourth step , the remaining left after the second step by etching using the same etching solution as the second step. method of manufacturing an exposure mask according to any one of claims 1 to 4, wherein removing a portion and the semi-transparent layer of the light-shielding portion.

Images