JP3919671B2 - Color filter manufacturing method and alignment mark - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a color filter manufacturing method using a colored resist (hereinafter referred to as a color resist), and an alignment mark used in the color filter manufacturing method.
[0002]
[Prior art]
  In recent years, applications of solid-state imaging devices such as CCDs (charge coupled devices) are spreading to digital still cameras, image input terminals for personal computers, and the like in addition to video movies and the like. At this time, it is necessary to use a primary color filter instead of the complementary color filter which has been the mainstream. The primary color filters are attracting attention because of their high signal processing simplicity and wide applicability. However, the manufacturing process is becoming increasingly finer, so the shift in dyeing is extremely large. It becomes difficult because it becomes larger (up to 1 μm in both horizontal and vertical directions).
[0003]
  Color filters manufactured by the traditional dyeing method are beginning to see limitations in resolution and uniformity, and primary color dyeing is somewhat lacking in process stability compared to complementary color dyeing. Therefore, immediate improvement measures are required. Under such circumstances, the formation of a color filter with the above-mentioned color resist, which has reached a certain level in the dispersibility and processability of pigments, although it still has some problems in terms of resolution and the like, attracts new attention. It ’s coming. In view of future progress in performance, the formation of a color filter using the color resist is considered to have a great effect not only in improving the characteristics of the solid-state imaging device but also in improving the yield during production and reducing the production cost. The color resist is a positive resist or negative resist in which a pigment is dispersed in a transparent base material, or a positive resist or negative resist in which a dye is uniformly dissolved.
[0004]
  However, the above-described method for manufacturing a color filter using a color resist has a problem in exposure alignment at the time of forming a blue filter as described in detail below. That is, in an exposure apparatus such as a stepper, the alignment mark on the substrate is usually detected using red light such as a He—Ne laser in the exposure alignment process. This is for avoiding resist exposure. However, on the other hand, there is a fact that the blue color resist has a very low transmittance of red light.
[0005]
  Normally, as shown in FIG. 6, the exposure alignment in the blue filter forming step is performed by using an alignment mark (base alignment mark) 2 formed on the base device substrate 1 as an overcoat film 3 that functions as a flattening film and blue. Detection is performed with the red light through the resist layer 4. However, since the red light is absorbed by the blue resist layer 4 in addition to the low contrast of the base alignment mark 2, the signal light reflected and diffracted by the base alignment mark 2 and incident on the detector (not shown) is It becomes extremely weak. Therefore, exposure alignment during the blue filter forming process is very difficult. Note that 5 is a filter of another color (for example, red), and 6 is a blue filter.
[0006]
  In order to solve the above-described problems, for example, improvement of the base alignment mark detectability is achieved by improving the alignment optical system as disclosed in JP-A-6-260390 and JP-A-4-133349. Or various methods such as a method of removing the color resist at the base alignment mark portion at the time of application as disclosed in JP-A-3-163403 and JP-A-8-297206. ing. However, both methods involve improvement of existing devices and introduction of new devices, and it is difficult to say that high throughput can be ensured and can be realized at low cost. Accordingly, there is a need for a simpler solution to the problem of exposure alignment during the blue filter forming process.
[0007]
  Recently, there has been proposed a method for manufacturing a color filter that improves the illuminance of an alignment mark without the need to improve the existing apparatus as described above or introduce a new apparatus (Japanese Patent Laid-Open No. 9-96712). In this color filter manufacturing method, as shown in FIG. 7A, the planarization layer 13 is formed so as to cover the alignment mark 12 on the substrate 11, and the transparent layer is formed at a position immediately above the alignment mark 12 in the planarization layer 13. 14 is formed. Next, the colored resist layer 15 is formed on the substrate 11 so that the thickness on the transparent layer 14 is thinner than the thickness of other portions. Then, the alignment mark 12 is detected by irradiation of the alignment light 16, and after aligning the photomask (not shown) with the substrate 11, exposure and development are performed, and a colored resist as shown in FIG. A color filter 17 having the pattern of the layer 15 is obtained. By doing so, since the colored resist layer 15 is thin immediately above the alignment mark 12, the illuminance of the alignment mark 12 is increased even when the colored resist layer 15 is a blue resist layer and the alignment light 16 is red light. It can be improved.
[0008]
  The color filter manufacturing method shown in FIG. 7 forms an alignment mark on a layer (for example, a polysilicon electrode or a light-shielding film layer) that determines a light receiving portion opening that has been conventionally performed in an on-chip process such as a solid-state imaging device. This method follows the method, and is considered to be a measure for improving the illuminance of the alignment mark without process improvement costs or significant process changes.
[0009]
[Problems to be solved by the invention]
  However, the conventional color filter manufacturing method has the following problems. That is, as shown in FIG. 7A, a thick planarization layer 13 is formed between the colored resist layer 15 that is the alignment target layer and the alignment mark 12. When such a planarization layer 13 is formed between the alignment target layer and the base alignment mark, a large distance difference occurs between the surface of the alignment target layer and the surface of the base alignment mark. Therefore, in particular, when laser light is used as alignment light, there is a problem that alignment errors are likely to occur due to refraction or ghost.
[0010]
  Furthermore, there remains a problem in terms of improving the contrast of the alignment mark necessary for mark recognition of the exposure apparatus. That is, the light intensity of the alignment light 16 is I, the light absorption coefficient of the colored resist 15 is α, and the film thickness of the colored resist 15 immediately above the alignment mark 12 is d1 / 2 (d1: the film thickness of the flat portion in the colored resist 15). When the reflectance of the substrate 11 is R0 and the reflectance of the alignment mark 12 is RM, the contrast C of the alignment mark 12 is expressed as C≈Ie−αd1 | (R0−RM) |. Therefore, the contrast C of the alignment mark 12 depends on the reflectance RM of the alignment mark 12. However, as described above, the base alignment mark is usually formed on a silicon compound layer that determines the opening of the light receiving portion such as a polysilicon electrode or a light shielding film layer. Accordingly, the reflectance RM is not significantly different from the reflectance R0 of the substrate 11 formed of silicon or silicon oxide, and the contrast C of the alignment mark 12 is lowered.
[0011]
  Furthermore, when the shape of the transparent layer 14 is the same as the shape of the alignment mark 12 and they are superimposed one on top of the other, either the light passing through the contours of both the transparent layer 14 and the alignment mark 12 Light passing through only one of them may be mixed, which may cause a false signal of the mark signal of the exposure apparatus.
[0012]
  That is, in the conventional color filter manufacturing method, an alignment error due to a large distance difference between the colored resist layer 15 and the alignment mark 12, a decrease in contrast of the alignment mark 12, generation of a false signal of the mark signal of the exposure apparatus, etc. The above problem remains, and there is a problem that high alignment accuracy cannot be ensured when the illuminance decreases due to absorption of red alignment light by the blue resist.
[0013]
  Therefore, the object of the present invention is to obtain high contrast under the blue resist when using red alignment light, to ensure high alignment accuracy, to ensure high throughput in the color filter forming process, and to increase the cost by improving the conventional process. Another object of the present invention is to provide a method for manufacturing a color filter capable of suppressing the above-described problem.
[0014]
[Means for Solving the Problems]
  In order to achieve the above object, the invention according to claim 1 provides several types of color filters.pluralIn the method for producing a color filter formed from a colored resist by photolithography technology, a colored resist having the lowest light transmittance for exposure alignment is selected from the colored resists. Different alignment marksUsing the color filter material for that colorAfter that, the color filter is formed by performing exposure alignment on the alignment mark.
[0015]
  According to the said structure, the alignment mark used when forming the color filter of the specific color with the lowest light transmittance for exposure alignment is a color other than the said specific color.Using the color filter material for that colorIt is formed. Therefore, when forming the color filter of the specific color having the lowest light transmittance for the exposure alignment, an alignment mark having a color higher in transmittance than the specific color can be used. Alternatively, a higher contrast can be obtained than when a transparent alignment mark is used.
[0016]
  In the invention according to claim 2, a plurality of types of color filters are provided.pluralIn a manufacturing method of a color filter formed from a colored resist by a photolithography technique, first, an alignment mark having the same color as the light color of the alignment optical system is formed.Using the color filter material for that colorAfter that, the color filter is formed by performing exposure alignment on the alignment mark.
[0017]
  According to the above configuration, when forming a color filter having a color different from the light color of the alignment optical system, exposure alignment is performed on the alignment mark having the same color as the light color of the alignment optical system. Therefore, for example, when the light of the alignment optical system is red, when forming a blue color filter having a low transmittance of red light, the red alignment mark having the highest transmittance is used. Thus, a higher contrast can be obtained than when the blue or transparent alignment mark is used.
[0018]
  According to a third aspect of the invention, there is provided a color filter manufacturing method for forming a blue filter from a blue colored resist by a photolithography technique using an exposure apparatus having a red light alignment optical system. Prior to the same color of light as the alignment optical systemRed color filter materialRed colored resist to red filter andRedWhen the alignment mark is formed and the blue filter is formed, the aboveRedThe alignment optical system performs exposure alignment on the alignment mark.
[0019]
  According to the above configuration, when forming a blue filter from a blue colored resist having low transmittance of red light from the alignment optical system, the red alignment mark having the highest transmittance is used. A higher contrast can be obtained than when the blue or transparent alignment mark is used.
[0020]
  According to a fourth aspect of the present invention, in the color filter manufacturing method according to the third aspect of the present invention, prior to forming an alignment mark from the red colored resist, at least the alignment mark is formed below the alignment mark formation region. It is characterized in that an undercoat layer having a size that covers the mark formation region and exhibiting a reflectance of a predetermined value or more is formed.
[0021]
  According to the above configuration, the undercoat layer having a high reflectivity is formed below the red alignment mark so as to cover at least the alignment mark formation region. Therefore, the red light emitted from the alignment optical system is efficiently incident on the alignment optical system with little loss and is used for detecting the alignment mark.
[0022]
  The invention according to claim 5 is the method for producing a color filter according to claim 3, wherein an antireflection layer exhibiting a refractive index of a predetermined value or less is formed on the blue colored resist for forming the blue filter. It is characterized by doing.
[0023]
  According to the above configuration, since the antireflective layer having a low refractive index is formed on the blue colored resist, the reflected light on the blue colored resist surface is weakened. Thus, the reflected light that becomes noise with respect to the light incident on the alignment optical system from the red alignment mark is weakened, and the contrast of the alignment mark is further increased.
[0024]
  The invention according to claim 6When forming multiple types of color filters from multiple colored resists by photolithography ,Depending on the alignment optics of the exposure equipmentPhoto mask for color filterAlignment mark used during exposure alignment, the same color as the light of the alignment optical systemUsing the color filter materialIt is characterized by being formed.
[0025]
  According to the above configuration, when forming a primary color filter having a color different from the light color of the alignment optical system, exposure alignment can be performed on the alignment mark of the same color as the light color of the alignment optical system. . Therefore, for example, when the light of the alignment optical system is red, when forming a blue primary color filter having a low transmittance of red light, the red alignment mark having the highest transmittance is used. A higher contrast can be obtained than when the blue or transparent alignment mark is used.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments. FIG. 1 shows an exposure alignment method when forming a blue filter in the first embodiment. A method for manufacturing a color filter in the present embodiment will be described with reference to FIG.
[0027]
  As shown in FIG. 1A, a base alignment mark 22 is formed on the base device substrate 21 by patterning a light shielding film layer or the like that determines a light receiving opening. Then, in order to flatten the unevenness of the underlying device and facilitate the formation of the color filter, a transparent acrylic resin is applied to the entire underlying device substrate 21 to form the overcoat film 23. After this, the color filter forming process is started.
[0028]
  In the color filter forming step, the red filter 24 is formed prior to the formation of the blue color filter. The red filter 24 is formed by applying a red resist (not shown) on the overcoat film 23, aligning a red filter photomask (not shown) with the base alignment mark 22, and then exposing, developing, and developing. It is formed by performing a post-baking process.
[0029]
  In the present embodiment, at the time of forming the red filter 24, at least the red alignment mark 25 used as an alignment mark at the time of forming the blue filter is simultaneously formed in the same manner as the red filter 24. The red alignment mark 25 has a shape used for normal alignment. Here, the red alignment mark 25 is desirably formed from a color resist layer having excellent mask linearity in terms of the finishing accuracy of the alignment mark. However, since the swelling due to dyeing is large, the dimensional shift is large, and if the bleeding and color mixing associated therewith can be taken into consideration in advance, it may be formed by the dyeing method described above.
[0030]
  Thus, when the red filter 24 and the red alignment mark 25 are formed, a blue filter 27 is formed as shown in FIG. 1B continuously or after forming an intermediate layer (for example, a green filter). To do. The blue filter 27 is formed by coating the entire surface with a blue resist 26 and irradiating the red alignment mark 25 formed simultaneously with the red filter 24 with the red alignment light 28 to align the photomask for blue filter (not shown). Then, exposure, development, and post-baking are performed to transfer the blue photomask filter pattern to the blue resist 26.
[0031]
  Here, in the normal film formation of the blue resist 26, the blue resist 26 is applied with a film thickness of about 1.0 μm. In the exposure alignment of the blue filter photomask, He-Ne laser light (red light) is used as a light source, and the film thickness d1 (see FIG. 2) of the blue color resist 26 immediately above the red alignment mark 25 and the red alignment mark 25 are used. When the ratio d1 / d0 to the film thickness d0 of the blue color resist 26 at the outer flat portion is d1 / d0 = 1/2, and the transmittance of the blue resist 26 with a film thickness of 1.0 μm is about 15%, the red alignment The ratio I1 / I0 between the transmitted light amount I1 of the mark 25 and the transmitted light amount I0 of the flat portion is I1 / I0≈2.6.
[0032]
  When a color resist having a high ability to bury a step is used as the blue resist 26, the film thickness d1 of the blue color resist 26 immediately above the red alignment mark 25 is relatively small. Accordingly, in this case, the value of the transmitted light amount ratio I1 / I0 can be increased, which is favorable from the viewpoint of signal detection of the exposure apparatus. However, the transmitted light of the blue color resist 26 in the flat portion and the transmitted light of the blue color resist 26 immediately above the red alignment mark 25 are reflected again by the surface of the underlying device (the reflectance is generally not high), and then again. The light passes through the blue resist 26 and enters the detection system of the exposure apparatus. Therefore, the transmitted light amounts IR1 and IR0 incident on the detection system are weak signals. Therefore, actually, as shown in FIG. 2, the reflected light R 1 and R 1 ′ at the boundary between the blue resist 26 and the overcoat film 23 and the red alignment mark 25 are greatly involved in the contrast of the red alignment mark 25. It is.
[0033]
  Here, exposure alignment is performed on the red alignment mark 25 with red alignment light as in the present embodiment, and exposure alignment is performed on the base alignment mark 12 via the transparent layer 14 as shown in FIG. Compare the contrast with the case.
[0034]
  In FIG. 3, the thickness of the color resist layer 15 on the transparent layer 14 is d5, the reflectance of the base alignment mark 12 is RM, and the reflectance of the base device substrate is R0. Further, the thickness of the color resist layer 26 on the red alignment mark 25 is d6, the thickness of the color resist layer 26 on the flat portion other than the alignment mark 25 is d7, and the reflectance of the alignment mark 25 is RM ′. The reflectance between the alignment mark 25 and the overcoat film 23 is R0 ′.
[0035]
  The contrast CA when exposure alignment is performed on the base alignment mark 12 via the color resist layer 15 and the transparent layer 14 is CA = | SA0−SA1 | ≈Ie−2αd5 | R0−RM |. On the other hand, the contrast CB in the present embodiment is CB = | SB0− (SB1 + SB1 ′) | ≈Ie−2αd6 | (e−2α (d7−d6) −1) R0′−RM ′ |. Here, if d7 >> d6, since e−2α (d7−d6) ≈0, CB≈Ie−2αd6 | R0 ′ + RM ′ | Therefore, the contrast ratio CA / CB of both is CA / CB≈ | (R0−RM) / (R0 ′ + RM ′) | · e−2α (d5−d6).
[0036]
  Usually, as the length of the transparent layer 14 or the alignment mark 25 formed on the flat layers 13 and 23 along the flat layers 13 and 23 becomes longer, the color resist layers 15 and 26 on the transparent layer 14 or the alignment mark 25 become longer. The thickness increases. Therefore, the size relationship between the length LT of the transparent layer 14 and the length LM of the alignment mark 12 (= the length of the alignment mark 25) is expressed as LT >> LM so that a false signal of the mark signal of the exposure apparatus is not generated. Then, d5> d6. Accordingly, the term “e-2α (d5-d6)” in the CA / CB formula is e-2α (d5-d6) <1. Further, as described above, the reflectance RM of the base alignment mark 12 made of transparent resin and the reflectance R0 of the base device substrate made of silicon or silicon oxide are substantially equal, and the term “R0− in the expression of the contrast ratio CA / CB”. “RM” is (R0−RM) ≈0. As a result, CA / CB becomes CA / CB <1. From the above, the contrast CB according to the present embodiment is higher than the contrast CA in the case of using the base alignment mark as shown in FIG.
[0037]
  As described above, in the present embodiment, after the light-shielding film layer and the like are patterned on the base device substrate 21 to form the base alignment mark 22, the overcoat film 23 is formed using a transparent acrylic resin. Then, after applying the red resist on the overcoat film 23, exposure alignment using the base alignment mark 22 is performed, and the red alignment mark 25 for forming the red filter 24 and the blue filter 27 is simultaneously formed by the photolithography technique. Further, when the blue filter 27 is formed, exposure alignment using the red alignment mark 25 is performed after the blue resist 26 is applied, and the blue filter 27 is formed by a photolithography technique. Thus, when the blue filter 27 is formed, the red alignment mark 25 that does not absorb red alignment light is used as a target for exposure alignment, and the transmitted light amount I1 of the red alignment mark 25 is used as the base alignment mark 22. Can be bigger. Further, the reflected light (R 1 + R 1 ′) relating to the red alignment mark 25 can be made larger than when the base alignment mark 22 is used. Therefore, according to the present embodiment, the contrast of the alignment mark when the blue filter 27 is formed can be sufficiently increased as compared with the case where the base alignment mark 22 is used.
[0038]
  Further, the alignment mark 25 at the time of forming the blue filter 27 is formed immediately below the blue resist 26 which is an alignment target layer, that is, on the color filter forming surface. Therefore, the surface of the alignment target layer 26 and the surface of the alignment mark 25 can be brought close to each other, and even when laser light is used as alignment light, alignment errors due to refraction and ghost are unlikely to occur.
[0039]
  Furthermore, in the present embodiment, as in the color filter manufacturing method disclosed in Japanese Patent Laid-Open No. 9-96712, a false signal with respect to the mark signal of the exposure apparatus is placed above the base alignment mark 22 and the red alignment mark 25. Does not form a transparent layer that can cause signal generation. Therefore, the generation of the false signal can be eliminated and the alignment accuracy can be improved.
[0040]
  Further, the red alignment mark 25 characterizing the present embodiment is formed simultaneously with the same technique as the red filter 24 forming technique when the red filter 24 is formed. Therefore, it is not necessary to make any changes to the manufacturing process of the conventional color filter that uses the base alignment mark as a target during exposure alignment. Therefore, the cost increase from the conventional color filter manufacturing process can be suppressed, and high throughput can be secured in the color filter forming process.
[0041]
  That is, in this embodiment, high exposure alignment accuracy can be obtained. Therefore, as shown in FIG. 1, even when the blue filters 27, 27,... Are formed between the red filters 24, 24,. Thus, a clear color filter pattern can be obtained.
[0042]
  FIG. 4 shows an exposure alignment method when forming a blue filter in the second embodiment. In the first embodiment, as described above, the light transmitted through the red alignment mark 25 is reflected on the surface of the underlying device having a low reflectance, so that the light incident on the detection system of the exposure apparatus is weak. Become. Therefore, in the present embodiment, the amount of reflected light transmitted through the red alignment mark is increased to effectively use the alignment light, thereby improving the exposure alignment accuracy. Hereinafter, a method for manufacturing a color filter in the present embodiment will be described with reference to FIG.
[0043]
  When forming the pattern of the light-receiving opening (not shown) and the base alignment mark 32 by using a highly reflective material such as the light shielding film (for example, Al (aluminum): surface reflectance is about 90%) in manufacturing the base device. Then, the mark undercoat layer 38 of the highly reflective material having a size enough to cover the entire area of the red alignment mark 35 is formed immediately below the formation position of the red alignment mark 35 on the base device substrate 31. Thereafter, in the same manner as in the first embodiment, an overcoat film 33, a red filter 34, a red alignment mark (blue filter forming alignment mark) 35, a blue resist 36, and a blue filter 37 are sequentially formed.
[0044]
  As described above, in the present embodiment, the mark undercoat layer 38 is formed of a highly reflective material immediately below the position where the red alignment mark 35 is formed on the underlying device substrate 31. Therefore, the transmitted light when the alignment light 39 is irradiated to the red alignment mark 35 is reflected by the mark undercoat layer 38 having a surface reflectance of about 90% formed immediately below. As a result, as in the first embodiment, it is possible to obtain a reflected light amount much higher than the case where the transmitted light of the red alignment mark 25 is simply reflected by the base device substrate 31, and the red light from the alignment optical system is lost. It is possible to efficiently use it for mark detection of an exposure apparatus without causing it to occur. Therefore, the exposure alignment accuracy when forming the blue filter using the red light alignment optical system can be dramatically improved.
[0045]
  FIG. 5 shows a cross section in the vicinity of the red alignment mark in the third embodiment. In order to emphasize the blue resist 46 and the reflected light R1, R1 'at the boundary between the overcoat film 43 and the red alignment mark 45, which are greatly involved in the contrast of the red alignment mark 45, reflection on the surface of the blue resist 46 is performed. The presence of the light Rb cannot be ignored. The reflected light Rb acts as a so-called noise component (offset) that has no useful information for the mark signal in the exposure apparatus. Therefore, in this embodiment, an antireflection layer 49 (for example, an antireflection material AZ Aquatar: manufactured by Clariant Japan Co., Ltd.) having a low refractive index (for example, a refractive index n = 1.4) is spun on the blue resist 46. Form by coating. Then, the reflected light Rb is canceled by reflecting the light Rb ′ having the opposite phase to the reflected light Rb from the surface of the antireflection layer 49. The refractive index and coating thickness of the antireflection layer 49 are determined by the wavelength of the incident light and the phase relationship between the reflected light Rb ′ on the surface of the antireflection layer 49 and the reflected light Rb on the surface of the blue resist 46. It may be determined by considering it.
[0046]
  In each of the above embodiments, red light such as He—Ne laser light is used as alignment light used during exposure alignment, and a blue color filter having the lowest transmittance for the red light among the three RGB colors is used. The case of forming is described as an example. However, the present invention is not limited to this. In short, a colored resist having a specific color with the lowest transmittance of the alignment light is selected from the colored resists forming the primary color filter, and a color different from the selected colored resist (preferably the transmittance is the highest). The alignment mark for the specific color may be formed with a high color).
[0047]
【The invention's effect】
  As apparent from the above, the color filter manufacturing method according to the first aspect of the present invention uses a specific color resist having the lowest light transmittance for exposure alignment among the color resists used for forming the color filter. Select an alignment mark with a color different from the selected specific color.Using the color filter material for that colorThe alignment filter is formed, and the alignment mark is subjected to exposure alignment, and the color filter is formed by a photolithography technique. Therefore, when forming the color filter of the specific color having the lowest light transmittance for the exposure alignment, It is possible to use an alignment mark of a color having a higher transmittance than the specific color. Therefore, a higher contrast can be obtained than when the alignment mark of the specific color or the transparent base alignment mark is used.
[0048]
  That is, according to the present invention, since the high contrast of the alignment mark can be obtained as described above, the mark detection accuracy by the exposure apparatus can be improved and the exposure alignment accuracy can be increased.
[0049]
  In the color filter manufacturing method according to the second aspect of the invention, first, an alignment mark for alignment having the same color as the light color of the alignment optical system is provided.Using the color filter material for that colorAfter that, the alignment mark is subjected to exposure alignment, and the color filter is formed by a photolithography technique. Therefore, a blue color filter having a low alignment light transmittance is formed by an exposure device of a red light alignment optical system. In this case, exposure alignment can be performed on the red alignment mark having the highest transmittance. Therefore, a higher contrast can be obtained than when the blue alignment mark or the transparent base alignment mark is used.
[0050]
  According to a third aspect of the present invention, when the blue filter is formed from the blue colored resist using the exposure apparatus having the red light alignment optical system, the light of the alignment optical system is firstly used. Same color asRed color filter materialRed colored resist to red filter andRedWhen the alignment mark is formed and the blue filter is formed, exposure alignment is performed on the red alignment mark. Therefore, when forming the blue filter from a blue colored resist having a low transmittance of red alignment light. The red alignment mark having the highest transmittance can be used. Therefore, a higher contrast can be obtained when forming a blue filter than when a blue alignment mark or a transparent alignment mark is used.
[0051]
  Furthermore, since the red alignment mark is formed together with the red filter from the red colored resist, the red alignment mark can be formed directly under the alignment target layer (colored resist layer). Therefore, the distance between the alignment layer and the alignment mark can be reduced, and alignment errors due to refraction and ghost can be prevented. That is, according to the present invention, the mark detection accuracy by the exposure apparatus can be improved, and the exposure alignment accuracy can be increased.
[0052]
  Furthermore, since the formation of the red alignment mark in the present invention is simultaneously performed by the same method when forming the red filter, the base alignment mark can be used as a target at the time of exposure alignment only by changing the pattern of the photomask for the red filter. This can be carried out without any change in the manufacturing process of the color filter. Therefore, it is possible to secure a high throughput in the color filter forming process while suppressing an increase in cost for the conventional color filter manufacturing process.
[0053]
  According to a fourth aspect of the present invention, there is provided a color filter manufacturing method that covers at least the alignment mark formation region below the alignment mark formation region prior to forming an alignment mark from the red colored resist. Since an undercoat layer exhibiting a reflectance greater than or equal to a predetermined value is formed, the amount of light that passes through the red alignment mark and returns to the alignment optical system can be increased, and the red light from the alignment optical system can be efficiently lost. It can be used for mark detection of the exposure apparatus. Therefore, it is possible to dramatically improve the alignment accuracy when forming the blue filter using the red light alignment optical system.
[0054]
  In the color filter manufacturing method of the invention according to claim 5, an antireflection layer exhibiting a refractive index of a predetermined value or less is formed on the blue colored resist for forming the blue filter. Reflected light on the surface of the blue colored resist that becomes noise with respect to light incident on the alignment optical system is weakened. Therefore, the contrast of the alignment mark when forming the blue filter can be further increased, and the exposure alignment accuracy can be increased.
[0055]
  Further, since the alignment mark of the invention according to claim 6 is the same color as the light of the alignment optical system, when forming a color filter of a color different from the color of the alignment light, the light of the alignment optical system is used. The exposure alignment can be performed on the alignment mark of the same color as this color. That is, for example, when using a red light alignment optical system, when forming the blue primary color filter having a low red light transmittance, the red alignment mark having the highest alignment light transmittance should be used. Therefore, a higher contrast can be obtained than when the blue alignment mark or the transparent alignment mark is used.
[Brief description of the drawings]
FIG. 1 is a diagram showing an exposure alignment method when forming a blue filter in the color filter manufacturing method of the present invention.
FIG. 2 is an explanatory diagram of reflected light regarding the red alignment mark in FIG. 1;
FIG. 3 is a comparison diagram of reflected light related to a red alignment mark in FIG. 1 and reflected light related to a conventional base alignment mark.
4 is a view showing an exposure alignment method when forming a blue filter different from FIG. 1. FIG.
FIG. 5 is a cross-sectional view of the vicinity of a red alignment mark when a blue filter different from FIGS. 1 and 4 is formed.
FIG. 6 is a view showing an exposure alignment method using a base alignment mark when forming a blue filter in a conventional color filter manufacturing method.
7 is a view showing an exposure alignment method using a base alignment mark at the time of forming a blue filter different from FIG. 6. FIG.
[Explanation of symbols]
21, 31 Base device substrate
22, 32 Base alignment mark
23, 33, 43 Overcoat film
24, 34 Red filter
25, 35, 45 Red alignment mark
26, 36, 46 Blue resist
27, 37 Blue filter
38 mark undercoat
49 Antireflection layer

Claims (6)

In a method for producing a color filter, in which a plurality of types of color filters are formed from a plurality of colored resists by photolithography technology,
Among the colored resists, a colored resist of a specific color having the lowest light transmittance for exposure alignment is selected, and an alignment mark of a color different from the selected specific color is selected using a color filter material for the color. Forming,
Then, the said color filter is formed by performing exposure alignment with respect to the said alignment mark, The manufacturing method of the color filter characterized by the above-mentioned. In a method for producing a color filter, in which a plurality of types of color filters are formed from a plurality of colored resists by photolithography technology,
First, an alignment mark of the same color as the light color of the alignment optical system is formed using the color filter material for the color ,
Then, the said color filter is formed by performing exposure alignment with respect to the said alignment mark, The manufacturing method of the color filter characterized by the above-mentioned. In a method of manufacturing a color filter that forms a blue filter from a blue colored resist by a photolithography technique using an exposure apparatus having an alignment optical system for red light,
Prior to the formation of the blue filter, a red filter and a red alignment mark are formed from a red colored resist, which is a red color filter material that is the same color as the light of the alignment optical system,
When forming the blue filter, the alignment optical system performs exposure alignment on the red alignment mark. In the manufacturing method of the color filter of Claim 3,
Prior to forming an alignment mark from the red colored resist, an undercoat layer that is at least a size that covers the alignment mark formation region and exhibits a reflectance of a predetermined value or more is formed below the alignment mark formation region. A method for producing a color filter characterized by the above. In the manufacturing method of the color filter of Claim 3,
A method for producing a color filter, comprising forming an antireflection layer exhibiting a refractive index of a predetermined value or less on a blue colored resist for forming the blue filter. An alignment mark used during exposure alignment of a photomask for a color filter by an alignment optical system of an exposure apparatus when a plurality of types of color filters are formed from a plurality of colored resists by photolithography technology ,
An alignment mark formed using a color filter material having the same color as the light of the alignment optical system.

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