JP4984400B2 - Solid-state imaging device and manufacturing method thereof - Google Patents

Description

  The present invention relates to an imaging device including a photoelectric conversion element typified by a C-MOS or CCD, and a manufacturing method thereof, and more particularly, to a color filter formed on the photoelectric conversion element.

  In recent years, solid-state imaging devices such as CCDs and C-MOSs mounted on digital cameras and the like have been increased in pixel size and miniaturization, and in particular, the pixel size of a finer one is less than 2 μm × 2 μm. .

  In addition, the solid-state imaging device has a color filter paired with the photoelectric conversion device for colorization. As a method for forming a color filter, a method of forming a pattern by a photolithography process is generally used (for example, see Patent Document 1).

  The region (opening) where the photoelectric conversion element on the solid-state image sensor contributes to photoelectric conversion depends on the size and the number of pixels of the solid-state image sensor, but is about 20 to 40% of the total area of the solid-state image sensor. However, since a small aperture leads to a decrease in sensitivity as it is, it is common to form a condensing microlens on the photoelectric conversion element to compensate for this.

  However, in recent years, the demand for high-definition CCD image sensors with more than 6 million pixels has increased, and the pixel size of the color filter associated with these high-definition CCDs has fallen below 2 μm × 2 μm. There is a problem that insufficient resolution of the color filter formed by the process adversely affects the characteristics of the solid-state imaging device. Such a lack of resolution appears as uneven color due to a defective shape of the pattern at a pixel size of 2.5 μm or less or in the vicinity of 1.8 μm. As the pixel size is reduced, the aspect ratio is increased (thickness is greater than the width), so the portion that should be removed (the non-effective portion of the pixel) cannot be completely removed, resulting in other residues It will adversely affect the color pixels.

  In order to remove the residue, a method such as extending the development time is performed. However, there has been a problem that the cured pixels are peeled off. Further, patterning by photolithography has a phenomenon that the edge of the pattern stands (can be horned), and when the pixel size becomes fine, this horn has an adverse effect on color filter performance such as color unevenness.

  Also, to obtain satisfactory spectral characteristics, the film thickness of the color filter must be increased, and as the film thickness of the color filter increases, the resolution of the pattern becomes rounder as the pixels become finer. It tends to decrease. When the concentration of the pigment contained in the color filter layer increases, the light necessary for the photocuring reaction does not reach the bottom of the color filter layer, so that the curing becomes insufficient, and peeling occurs in the development process in photolithography, resulting in pixel defects. was there.

  Furthermore, when the color filter is thick, not only the problem due to the manufacturing process, but also the problem that light incident from an oblique direction passes through another adjacent color filter pattern and enters the photoelectric conversion element, resulting in color mixing and a decrease in sensitivity. To do. This problem becomes more prominent as the pixel size of the color filter becomes smaller.

  From the above, in order to increase the number of pixels of the solid-state imaging device, in addition to the high-definition pattern of the color filter, thinning is also an important problem.

  The problem of color mixing of incident light also occurs when the distance between the color filter and the photoelectric conversion element is large.

  In addition, the aperture ratio of the microlens associated with a high-definition solid-state image sensor (that is, sensitivity reduction) and image quality degradation due to increased noise such as flare and smear have become major problems. In order to improve the light condensing property and to improve the S / N ratio in the photoelectric conversion element, it is necessary to make the microlens lower distance small (thin). When the microlens lower distance is large, there are the following two problems.

  First, when the distance under the lens is large, the incident light capturing angle becomes small, the incident light quantity decreases, and the display becomes dark overall. Secondly, in a camera using a photoelectric conversion element such as a C-MOS or CCD, the angle of incident light usually changes depending on the aperture (F value) of the objective lens, and oblique light increases on the open side, thereby collecting light. The sensitivity decreases due to the decrease, and the angle of the incident light is greatly different between the center and the end of the pixel area of the semiconductor chip on which the photoelectric conversion element is formed. Therefore, the incident light to the end pixel (photoelectric conversion element) It was lowered and the display was dark at the edge of the display screen.

On the other hand, a green resist has a lower refractive index after curing than a red resist or a blue resist, which has been a problem in designing a solid-state imaging device. In other words, it is difficult to select a resin having a high refractive index after curing because the color resist used in the photolithography process requires photosensitivity, and the difference in refractive index between the three color filters is difficult. Therefore, there has been a problem that the reflectance varies.
Japanese Patent Laid-Open No. 11-68076

  As described above, the color filter formed by the conventional photolithography process has a problem that sufficient resolution cannot be obtained, residue is likely to remain, and pixel peeling is likely to occur, which deteriorates the characteristics of the solid-state imaging device. There was a problem of letting. In addition, it has been difficult to reduce the thickness of the color filter to reduce the thickness of the solid-state imaging device. In addition, there is a problem that the distance between the color filter and the photoelectric conversion element is large.

  The present invention has been made in view of the above-described problems, and is formed without causing pattern shape defects, residues, peeling, etc., can be thinned, has a small distance from the photoelectric conversion element, and has a pixel. An object of the present invention is to provide a solid-state imaging device including a color filter having no variation in reflectance between the two and a method for manufacturing the same.

In order to solve the above-described problem, a first aspect of the present invention is a photoelectric conversion element that is two-dimensionally arranged on a semiconductor substrate, and is disposed on the semiconductor substrate corresponding to each of the photoelectric conversion elements. A method of manufacturing a solid-state imaging device comprising a color filter having a plurality of color filter patterns and a planarization layer formed on a part or all of the semiconductor substrate, wherein the plurality of color filter patterns are A color formed by a forming method for patterning a predetermined color filter layer by dry etching and a forming method for patterning another color filter layer by photolithography, and formed at least first among the color filter patterns of the plurality of colors By dry etching the filter pattern, unnecessary portions of the color filter layer and the underlying flattening layer And a step of forming and patterning step, and the other color filter patterns by photolithography to formation, and the contact other color filter pattern formed by the formed color filter pattern the photolithographic by the dry etching A method for manufacturing a solid-state imaging device is provided.

  If dry etching is used, the resin resist used as a mask can be freely selected from resists for semiconductors with higher resolution than color resists, so the color filter pattern of the fine pattern is smooth and the residue is peeled off. Patterning can be performed without any problem.

  At this time, when patterning the second and subsequent color filter patterns by dry etching, if the means for protecting the surface of the previously formed color filter pattern is not provided, the surface of the formed color filter pattern is roughened by dry etching. The problem of being degenerated occurs. In addition, there is a problem in that the unevenness of the color filter pattern formed earlier affects the color filter layer provided later.

  Therefore, at least the first color filter pattern is patterned by dry etching, and the remaining color filter patterns are patterned by photolithography. In particular, the first color filter pattern is patterned by dry etching.

  In this way, the surface of the color filter pattern of the first color will not be roughened by the patterning process of the remaining color filters without special protection, and the color filter patterns of the second and subsequent colors are firmly attached to the lower layer. By being sandwiched between the first color filter patterns, it is possible to prevent peeling during development.

  In addition, since the accuracy of the color filter pattern that is formed first greatly affects the accuracy of the entire color filter, at least the color filter pattern that is formed first has a high accuracy of the entire color filter according to the dry etching method. Therefore, a solid-state imaging device having a large number of pixels without color unevenness can be obtained.

  In general, the thickness of the color filter pattern differs because the spectral characteristics required for each color are different and the resin and pigment used are different. In addition, since the color filter pattern formed by dry etching does not need to have photosensitivity, the pigment concentration can be increased. Therefore, it can be made thinner than the color filter pattern by photolithography.

  When the color filter pattern is formed by dry etching, the thickness difference that differs from one color filter pattern to another, especially the color filter pattern formed by photolithography, is absorbed by the dry etching up to the planarization layer. Therefore, it is possible to provide a solid-state imaging device including a color filter having a small surface step due to color and a small distance from the photoelectric conversion device.

  According to a second aspect of the present invention, in the forming method for patterning the predetermined color filter by dry etching, an unnecessary portion of the predetermined color filter layer and a planarizing layer thereunder are dry-etched until reaching the semiconductor substrate. The method of manufacturing a solid-state imaging device according to claim 1, wherein the method is a construction method.

  Since the surface of the planarizing layer is rough during dry etching, the color filter pattern resist residue tends to remain. These residues are not preferable as the distance from the photoelectric conversion element becomes shorter, which may affect the image quality as noise or defect. Generation of this residue can be prevented by removing all of the planarization layer and providing a color filter pattern by photolithography directly on the semiconductor substrate. Specifically, etching is performed until all the planarization layer is removed during dry etching, so that no planarization layer remains in the lower layer of the color filter pattern formed by photolithography.

  Note that when a color filter pattern is directly formed on a semiconductor substrate by a photolithography method, there is a problem that the photoresist does not have sufficient adhesion to the semiconductor substrate and peels off during development. In the present invention, the color provided by dry etching is used. Since the color filter pattern provided by the dry etching adjacent to the filter pattern serves as an anchor, it is possible to prevent the color filter pattern provided by the photolithography method from dropping off.

  The third aspect of the present invention is the method of manufacturing a solid-state imaging device according to claim 1 or 2, wherein the color filter pattern having the widest area among the plurality of color filter patterns is patterned by dry etching. provide.

  If the color filter pattern with the widest area is patterned by dry etching, the color filter pattern by photolithography can be efficiently retained, and the accuracy of the color filter pattern with the widest area greatly affects the accuracy of the entire color filter. Because.

  Further, when the color filter pattern has a multilayer structure, it is still effective if the color filter pattern provided in the lower layer (the one closer to the semiconductor substrate) is provided by dry etching.

  According to a fourth aspect of the present invention, the filter patterns of the plurality of colors include a green filter pattern, a red filter pattern, and a blue filter pattern, and either or both of the green filter and the red filter are patterned by the dry etching. A method for producing a solid-state imaging device according to claim 1 or 2 is provided.

  By patterning either or both of the green filter layer and the red filter layer with high pigment concentration, which are likely to be insufficiently exposed by the photolithography method, by dry etching, it is possible to obtain a color filter with no residue or pattern peeling. Therefore, a solid-state imaging device with high definition and no color unevenness can be obtained.

  In a fifth aspect of the present invention, the color filter layer patterned by the dry etching includes at least a thermosetting resin, and the color filter layer patterned by the photolithography includes at least a photocurable resin. A method for manufacturing a solid-state imaging device according to any one of claims 1 to 4 is provided.

  Since the color filter pattern including the thermosetting resin is firmly attached to the semiconductor substrate or the planarization layer, the color filter pattern does not peel off. In addition, the color filter resist containing a thermosetting resin can increase the concentration of the color material contained in it, so that the color filter can be made thinner, color mixing of incident light can be prevented, and the solid-state imaging device can be made thinner. Can be achieved.

According to a sixth aspect of the present invention, there is provided a photoelectric conversion element two-dimensionally arranged on a semiconductor substrate, and a color filter pattern of a plurality of colors disposed on the semiconductor substrate corresponding to each of the photoelectric conversion elements. A solid-state imaging device comprising a color filter having a color filter and a planarization layer formed on a part or all of the semiconductor substrate, wherein the planarization layer under the color filter pattern of the plurality of colors is formed by dry etching a certain color filter patterns, the between the other color filter pattern formed by photolithography after forming the color filter pattern with a dry etching Ri is Do different thickness, the color filter pattern formed by the dry etching And other color filter patterns formed by photolithography are in contact with each other. To provide a solid-state imaging device, characterized in that.

  By absorbing different thicknesses between the color filter patterns with the planarization layer, it is possible to provide a solid-state imaging device including a color filter having a uniform surface thickness.

According to a seventh aspect of the present invention, there is provided a photoelectric conversion element two-dimensionally arranged on a semiconductor substrate, and a color filter pattern of a plurality of colors disposed on the semiconductor substrate corresponding to each of the photoelectric conversion elements. A solid-state imaging device comprising a color filter having a planarization layer formed on a part or all of the semiconductor substrate, wherein the color filter is formed on the semiconductor substrate via the planarization layer. a color filter pattern formed by dry etching which is formed directly, color filters der with both other color filter pattern formed by photolithography after forming the color filter pattern by the dry etching The color filter pattern formed by the dry etching and the photolithography To provide a solid-state imaging device, characterized in that the other color filter patterns more formed is in contact.

  By absorbing different thicknesses between color filter patterns with a flattening layer, a color filter with a uniform surface thickness is provided, and a flattening layer is provided only in the minimum necessary locations, so that the color filter and photoelectric conversion are provided. A solid-state imaging device having a small distance from the device can be provided.

According to an eighth aspect of the present invention, there is provided a photoelectric conversion element two-dimensionally arranged on a semiconductor substrate, and a color filter pattern of a plurality of colors disposed on the semiconductor substrate corresponding to each of the photoelectric conversion elements. a color filter having, a solid-state imaging device having a planarizing layer part or formed all over the semiconductor substrate, a portion of the color filter pattern among the plurality of colors of color filter pattern is thermoset includes a resin having sex, the thermosetting remaining colors formed after forming the color filter pattern comprising a resin having a filter pattern viewed contains a resin having a photo-curable, a resin having the thermosetting Provided is a solid-state imaging device characterized in that a color filter pattern including a color filter pattern including the photocurable resin is in contact.

  Since the color filter pattern including the thermosetting resin is firmly attached to the semiconductor substrate or the planarization layer, the color filter pattern does not peel off. In addition, the color filter resist containing a thermosetting resin can increase the concentration of the color material contained in it, so that the color filter can be made thinner, color mixing of incident light can be prevented, and the solid-state imaging device can be made thinner. Can be achieved.

  According to a ninth aspect of the present invention, the plurality of color filter patterns include a green filter pattern, and a resin included in the green filter pattern has a higher refractive index than a resin included in another color filter pattern. A solid-state imaging device according to any one of claims 6 to 8 is provided.

  By making the refractive index of the resin contained in the green filter pattern higher than that of the resin contained in the other color filter patterns, the refractive index between the color filter patterns is approximated, and the condensing effect by the micro lens is on each color filter. An equivalent solid-state imaging device can be obtained.

  Furthermore, since a resin having a high refractive index tends to have a low etching rate, a smooth color filter pattern can be obtained by patterning a layer to which a resin having a high refractive index is added by dry etching.

  The tenth aspect of the present invention further includes a microlens disposed on the color filter, either directly or indirectly, corresponding to each of the photoelectric conversion elements. The solid-state imaging device according to claim 6, wherein the solid-state imaging device is configured by a part of a color filter.

  By configuring the peripheral portion of the microlens with a part of the color filter, a solid-state imaging device having a small microlens lower distance can be obtained.

  According to the first aspect of the present invention, there is provided a solid-state imaging device having a color filter that is high-definition, has no residue or omission, has a smooth edge, has a small surface step due to color, and has a small distance from the photoelectric conversion device. A manufacturing method is provided.

  According to the second aspect of the present invention, there is provided a solid-state imaging device having a color filter that further enhances the same effect as the first aspect of the present invention, has no residue, and has a smaller distance from the photoelectric conversion element. A manufacturing method is provided.

  According to the first aspect and the second aspect of the present invention, the distance between the color filter and the photoelectric conversion element is reduced. Therefore, if the solid-state imaging device including the microlens is used, the microlens and the photoelectric conversion element The distance can also be reduced.

  According to the third aspect of the present invention, the same effect as the first aspect or the second aspect of the present invention can be obtained.

  According to the fourth aspect of the present invention, the same effect as the first aspect or the second aspect of the present invention can be obtained.

  According to the fifth aspect of the present invention, in addition to the same effects as those of the first aspect or the second aspect of the present invention, the color filter can be made thin, so that color mixing of incident light is prevented, and a solid-state image sensor is provided. Can be made thinner.

  According to the sixth aspect of the present invention, there is provided a solid-state imaging device including a color filter that is high-definition, has no residue or omission, has a smooth edge, has a small surface step due to color, and has a small distance from the photoelectric conversion device. Provided.

  According to the seventh aspect of the present invention, there is provided a solid-state imaging device having a color filter that further enhances the same effect as the sixth aspect of the present invention, has no residue, and has a smaller distance from the photoelectric conversion element. Provided.

  According to the sixth aspect and the seventh aspect of the present invention, since the distance between the color filter and the photoelectric conversion element is small, the distance between the microlens and the photoelectric conversion element is obtained when the solid-state imaging device includes the microlens. Can also be reduced.

  According to the eighth aspect of the present invention, there is provided a solid-state imaging device provided with a thin color filter with high definition, no residue or omission, smooth edges, and the like.

  According to the ninth aspect of the present invention, there is provided a color filter having high definition, no residue or omission, smooth edges, little color filter pattern surface roughness, and the same light collecting effect between the color filter patterns. A solid-state imaging device is provided.

  According to the tenth aspect of the present invention, a solid-state imaging device having a small microlens lower distance is provided.

  Hereinafter, embodiments of the present invention will be described in detail.

  First, two color filter pattern forming methods used in the present invention will be described.

  The formation method of patterning by dry etching used in the present invention is to form a resin pattern in the shape of the object on the object forming layer, and dry etching using this as a mask to form the object in the object forming layer. This is a method of transferring and patterning. Specifically, as shown in FIG. 6, the object forming layer is a color filter layer 32 formed on the base material 31, and the photosensitive resin layer 33 is patterned on the object, A resin pattern 34 in the shape of an object is formed of a photosensitive resin, and the shape of the resin pattern 34 is transferred to the color filter layer 32 using this as a mask to form a color filter pattern 35 as a target object.

  The formation method of patterning by photolithography used in the present invention is to form a photosensitive object-forming layer, expose it through a mask, photocure, develop and remove unnecessary portions to perform patterning This is a method for obtaining the desired object. Specifically, as shown in FIG. 7, a color filter layer 42, which is an object-forming layer, is formed on a substrate 41 with a photosensitive resin composition, and this is exposed and cured through a mask, and developed. The unnecessary portion 42b is removed with a liquid to leave the photocuring portion 42a, and heat curing is performed as necessary to form the color filter pattern 43 that is the object.

  FIG. 1 is a partial cross-sectional view of a solid-state imaging device according to an embodiment of the present invention. 2 and 3 are partial cross-sectional views for explaining the manufacturing method of the solid-state imaging device shown in FIG. 1 in the order of steps. FIG. 4 is a plan view of FIG.

  As shown in FIG. 1, a solid-state imaging device according to an embodiment of the present invention is two-dimensionally arranged on a semiconductor substrate 10 on which a photoelectric conversion device 11 having a function of converting light into an electrical signal is formed. A leveling layer 12 having a level difference, a color filter 13 for color-separating incident light formed on the leveling layer 12, and a plurality of transfer lenses 14 disposed on the color filter 12. .

  Such a solid-state imaging device can be manufactured by the method shown in FIGS.

  First, as shown in FIG. 2B, the first planarization layer 22 is formed on the semiconductor substrate 20 (see FIG. 2A) having the photoelectric conversion elements 21 arranged two-dimensionally. As the first planarizing layer, a resin containing one or more resins such as acrylic, epoxy, polyimide, phenol novolac, polyester, urethane, melamine, urea, and styrene is used. Can do.

  Next, as shown in FIG. 2C, a green resist layer 23 is formed on the first planarization layer 22. The green resist layer 23 is formed by applying a thermosetting resin as a main component and applying a resin dispersion in which a green pigment is dispersed on the planarizing layer 22 and thermosetting it.

  Next, a predetermined resin pattern 24 is formed on the green resist layer 22 by photolithography, for example, as shown in FIG. As the resin pattern 24, for example, acrylic resin, epoxy resin, polyimide resin, phenol novolac resin, and other resins having photosensitivity can be used singly or in a mixture or copolymerization. There are steppers, aligners, mirror projection aligners, etc., which are used in the photolithography process for patterning photosensitive resin, but steppers are usually used to form color filters for solid-state image sensors that require high pixels and miniaturization. It is common to use.

  Thereafter, using this resin pattern 24 as a mask, the green resist layer 23 is patterned by dry etching to form a green filter pattern 25a as shown in FIG. As dry etching, for example, ECR, parallel plate magnetron, DRM, ICP, or dual frequency type RIE can be used.

  The gas used for dry etching may be a reactive (oxidative / reducing) gas, that is, an etching gas, for example, a gas having a halogen element such as fluorine, chlorine, bromine, etc. In addition, a gas having an oxygen or sulfur element in its structure can be used, but it is not limited thereto.

  Thereafter, a blue filter pattern 25b and a red filter pattern (not shown) are formed by photolithography, and as shown in FIG. 3B, a color filter 26 composed of green, blue and red filter patterns is formed.

  FIG. 4 is a plan view showing the arrangement of each color filter pattern of the color filter 26. The arrangement shown in FIG. 4 is a so-called Bayer arrangement in which a G (green) filter is provided every other pixel, and an R (red) filter and a B (blue) filter are provided every other row between the G filters. A sectional view taken along line A-A 'in FIG. 4 is shown in FIG.

  Next, as shown in FIG. 3C, a second planarization layer 27 is formed on the color filter 26 formed as described above. As the second planarization layer, a resin such as acrylic, epoxy, polyimide, phenol novolac, polyester, urethane, melamine, urea, styrene, etc. is used as in the first planarization layer. One or a plurality of resins can be used.

  Next, as shown in FIG. 3D, a lens matrix 28 is formed on the second planarization layer 27 by a heat flow method that is a well-known technique. The lens matrix 28 is preferably a photosensitive resin, and an alkali-soluble and heat-flowable resin such as an acrylic resin, a phenol resin, or a polystyrene resin can be used.

  Finally, an etching process is performed using the lens matrix 28 as a mask, and the shape of the lens matrix 28 is transferred to the second planarization layer 27 to form the microlens 29. At this time, the color filter 26 is removed from the boundary surface of each pattern to a depth of 0.03 μm to 0.5 μm, and the solid-state imaging device is completed as shown in FIG.

  In the manufacturing method of the solid-state imaging device described above, the green filter pattern 25a is formed by patterning by dry etching after completely curing the green resist layer 23, so that the development process in the later photolithography is performed. In this case, no pixel defect occurs.

  In the embodiment described above, it is desirable that the green filter pattern 25a has the largest area. By doing so, the adhesiveness with the base can be further strengthened, and pixel defects can be more effectively prevented. The area of the green filter pattern having the largest area can be, for example, 1 to 2 times the area of the color filter pattern having the smallest area. Further, by forming the color filter pattern having the largest area by the dry etching method, the color filter pattern occupying the widest area can be accurately patterned, and the accuracy of the entire color filter is improved. Specifically, the green filter pattern often has the largest area.

  In addition, by forming a color filter layer with a high pigment concentration, i.e., a low content of resin involved in curing, by patterning by a dry etching method, curing is insufficient in a normal photolithography process. Even a color filter layer can be formed with high accuracy and no residue or peeling. Specifically, this effect is obtained in the case of a red filter pattern or a green filter pattern.

  Alternatively, by forming a color filter layer by patterning by dry etching, the color filter layer that is insufficiently exposed due to the low transmittance of the exposure wavelength used for patterning by photolithography, resulting in a decrease in resolution and peeling, Even a color filter layer that is insufficiently cured by a normal photolithography process can be formed with high accuracy and without residue or peeling. This effect is particularly effective in the case of a blue filter pattern.

  For any reason, if the first pattern is formed by the dry etching method, it adheres to the underlying substrate, has no residue or peeling, and has a high-resolution color filter pattern. If the next color filter pattern is formed by the lithography forming method, the first formed color filter pattern is an accurate pattern and firmly adhered to the substrate, so even if it is a photolithography forming method, It is possible to accurately form a color filter pattern without peeling.

  In the case of a color filter consisting of three colors, there is a problem that when the color filter pattern is continuously formed by the dry etching forming method, the unevenness of the color filter pattern formed first cracks in the color filter layer to be formed later. In the case of a color filter comprising the first one color and four colors, it is preferable that the first color or the first and second colors are patterned by a dry etching method, and the remaining colors are patterned by a photolithography method.

  Moreover, the resin contained in the green filter pattern can have a higher refractive index than the resin contained in the blue and red filter patterns. Conventionally, since the refractive index of the green filter pattern is lower than the refractive index of other filter patterns, there is a problem that the reflectance of the color filter is not uniform. In order to increase the refractive index of the green filter pattern, a resin having a high refractive index may be used. However, because of the limitation of being used for photolithography, a resin having a narrow selection range and a resin having a high refractive index should be selected. Was difficult.

  On the other hand, in this embodiment, since the green filter pattern is formed by dry etching without depending on photolithography, a resin having a high refractive index among thermosetting resins is used as a resin for the green filter pattern. A wide selection is possible.

  In this way, the refractive index of the three-color filter pattern can be approximated by making the resin contained in the green filter pattern have a higher refractive index than the resin contained in the blue and red filter patterns. As a result, the light condensing effect by the microlens can be made equal, so that a good solid-state imaging device can be obtained.

  Furthermore, since a resin having a high refractive index tends to have a low etching rate, a smooth color filter pattern can be obtained by patterning a layer to which a resin having a high refractive index is added by dry etching.

  Since the green filter pattern of the present invention can obtain the same refractive index when it becomes a color filter pattern, it is about 0.05 to 0.2 than the refractive index of the resin contained in the blue and red filter patterns. A resin having a high refractive index is preferably used.

  In addition, as resin contained in the filter pattern of blue and red, acrylic, epoxy, polyimide, phenol novolac, polyester, urethane, melamine, urea having a refractive index of 1.5 to 1.6 As a resin contained in the green filter pattern, an acrylic, epoxy, polyimide, phenol novolac, polyester, urethane, melamine having a refractive index of 1.55 to 1.7 is used. Resins containing one or more resins such as those based on urea, urea, styrene, and copolymers thereof can be used. In particular, in order to achieve a high refractive index, a phenol resin, a polystyrene resin, or a polymer or monomer having a benzene ring or aromatic ring introduced, or an acrylic resin having a halogen group or a group having a sulfur atom introduced into the skeleton Can be used.

  Further, in the microlens formation step, as shown in FIG. 3E, the boundary portion between adjacent filter patterns is removed from the surface to a depth of 0.03 μm to 0.5 μm, and the peripheral portion of the microlens is a color filter. 26, the distance below the microlens can be reduced, and a solid-state imaging device with good sensitivity can be obtained.

  Here, the reason why the lower limit of the depth to be removed at the boundary portion between adjacent filter patterns is set to 0.03 μm is that it is the minimum value that can effectively identify the film thickness by SEM or AFM. The reason why the upper limit is set to 0.5 μm is that when the thickness exceeds 0.5 μm, the film surface becomes rough and the sensitivity is lowered due to surface scattering. Further, if it exceeds 0.5 μm, the effective color filter film thickness may be increased to, for example, 1 μm or more, and the film thickness is not one of the problems of the present invention.

  Hereinafter, the present invention will be described more specifically by showing examples of the present invention.

Example 1
With reference to FIG.2 and FIG.3, the manufacturing method of the solid-state image sensor which concerns on a present Example is demonstrated.

  After spin-coating a coating liquid mainly composed of an acrylic resin at a rotational speed of 2000 rpm on a semiconductor substrate 20 including two-dimensionally arranged photoelectric conversion elements 21 as shown in FIG. Baking was performed at 230 ° C. for 6 minutes using a hot plate to form the first planarization layer 22 as shown in FIG. At this time, the thickness of the first planarization layer 22 was 0.45 μm.

  Next, a pigment-dispersed green resist is spin-coated on the first planarization layer 22 at a rotation speed of 1000 rpm, and baked at 230 ° C. for 6 minutes. As shown in FIG. Formed. At this time, the color index of the green pigment is C.I. I. PG36 is used, and the pigment concentration is 35% by weight and the film thickness is 0.5 μm. Further, as the resin which is the main component of the green resist, a thermosetting acrylic high refractive index resin was used. Therefore, the refractive index of the green resist layer 23 is 1.65.

  As described above, by using a thermosetting acrylic high refractive index resin, a thermosetting agent is required, but a photopolymerization initiator and other sensitizers can be eliminated, and alkali development characteristics and photocuring properties can be eliminated. Since the photolithography characteristics such as the above are not necessary, the green filter can be made thinner by increasing the pigment concentration.

  Next, a coating solution mainly composed of an acrylic photosensitive resin is spin-coated on the green resist layer 23 at a rotational speed of 3000 rpm, and then patterned by photolithography. As shown in FIG. A pattern 24 was formed. At this time, since the transparent resin serving as a mask can be selected from a resin that does not contain a substance that hinders resolution such as a pigment, patterning can be performed with high definition.

  Thereafter, using the transparent resin pattern 24 as a mask, the green resist layer 23 was etched using a chlorofluorocarbon gas with a dry etching apparatus to form a green filter pattern 25a as shown in FIG. . At this time, the film thickness of the green filter pattern 25a is 0.5 μm, and the first planarizing layer 22 is partially removed, so that there is a 0.4 μm step between the adjacent first planarizing layer 22. Was formed.

  Thereafter, as shown in FIG. 3B, a blue filter pattern 25b and a red filter pattern (not shown) were sequentially formed by photolithography to obtain a color filter 26. At this time, the pigments used for the blue resist are C.I. I. PB15: 6, C.I. I. PV23, the pigment concentration is 30% by weight, the film thickness is 0.9 μm, the refractive index is 1.64, and the pigment used for the red resist is C.I. I. PR117, C.I. I. PR48: 1, C.I. I. PY139, the pigment concentration was 40% by weight, the film thickness was 0.9 μm, and the refractive index was 1.69.

  Further, on the color filter 26 formed in this manner, a coating solution containing an acrylic resin to which a UV absorber is added is spin-coated at a rotation speed of 1000 rpm, and subjected to a heat treatment at 200 ° C. for 10 minutes on a hot plate. The resin was cured to form a second planarization layer 27 as shown in FIG.

  Next, as shown in FIG. 3D, a lens matrix 28 made of an acrylic resin having photosensitivity and heat flow was formed on the planarizing layer 27 by a heat flow method that is a well-known technique.

  Finally, in a dry etching apparatus, an etching process is performed by using a fluorocarbon gas using the lens matrix 28 as a mask, and the shape of the lens matrix 28 is transferred to the second planarizing layer 27 to obtain a microlens. 29 was formed. At this time, it was removed to a depth of 0.2 μm from the boundary surface of each pattern of the color filter 26 to complete a solid-state imaging device as shown in FIG.

  In the manufacturing method of the solid-state imaging device as described above, the green filter pattern 25a is formed by using a pattern forming method by dry etching, so that a thin color filter having a fine pattern thickness can be obtained with a good shape and no residue. It was possible to form without pixel peeling. In addition, since the thermosetting resin is used for the green filter layer, the concentration of the color material in the solid content can be increased, so that the color filter can be formed thin, and a thin solid-state imaging device can be obtained. .

  In this example, a thermosetting acrylic resin was used as the main component of the green resist and blue resist formed by the shape transfer technique by dry etching, but epoxy resin, polyimide resin, phenol, and the like were not particularly concerned with acrylic resin. It is also possible to use a resin including one or more kinds of resins such as a novolac resin, a polyester resin, a urethane resin, a melamine resin, a urea resin, a styrene resin, and a copolymer thereof.

  In particular, in order to achieve a high refractive index, a phenol resin, a polystyrene resin, or a polymer or monomer into which a benzene ring or an aromatic ring is introduced, and an acrylic resin in which a halogen group or a sulfur group is introduced into the skeleton of these polymers, etc. Can be used.

  This makes it possible to achieve a high refractive index even in a green filter pattern that has the lowest refractive index and a large surface reflection compared to the blue filter pattern and the red filter pattern, and has a good sensitivity. Can be obtained.

  In the above embodiments, the green filter pattern is formed by patterning using dry etching. However, a blue filter pattern or a red filter pattern having a high pigment concentration that is easily peeled off by a photolithography process is formed by dry etching. It doesn't matter. However, since the adhesion and pattern accuracy of the first color green filter pattern are the most important, it is necessary to form the green filter pattern by a shape transfer technique using a dry etching technique. In addition, a red filter pattern may be formed as the second color after the green filter pattern is formed. However, since the red filter pattern has a high pigment concentration, residue is likely to remain, so the blue filter pattern is formed as the second color. Is desirable.

  In the present embodiment, a step of 0.4 μm is provided in the first planarizing layer 22 disposed below the color filter 26. However, the transparent resin pattern 24 serving as a matrix for forming the green filter pattern is provided. The first planarization layer may be etched within the range of 0.03 μm to 0.5 μm by adjusting the etching rate by selecting the thickness and material. Here, the lower limit is set to 0.03 μm because it is the minimum value that allows effective identification of the film thickness by SEM or AFM, and the upper limit is set to 0.5 μm. This is because if the level difference exceeds, there will be a film surface and the sensitivity will decrease due to surface scattering.

  Further, in this embodiment, the microlens is formed by dry etching, but the microlens may be formed by a conventional heat flow method. However, in order to reduce the thickness under the microlens, it is more preferable to form the microlens using a shape transfer technique by dry etching.

Example 2
With reference to FIG.2 and FIG.5, the manufacturing method of the solid-state image sensor which concerns on a present Example is demonstrated.

  After spin-coating a coating liquid mainly composed of an acrylic resin at a rotational speed of 2000 rpm on a semiconductor substrate 20 including two-dimensionally arranged photoelectric conversion elements 21 as shown in FIG. Baking was performed at 230 ° C. for 6 minutes using a hot plate to form the first planarization layer 22 as shown in FIG. At this time, the film thickness of the first planarizing layer 22 was 0.4 μm.

  Next, a pigment-dispersed green resist is spin-coated on the first planarization layer 22 at a rotation speed of 1000 rpm, and baked at 230 ° C. for 6 minutes. As shown in FIG. Formed. At this time, the color index of the green pigment is C.I. I. PG36 is used, and the pigment concentration is 40% by weight and the film thickness is 0.5 μm. Further, as the resin which is the main component of the green resist, a thermosetting acrylic high refractive index resin was used. Therefore, the refractive index of the green resist layer 23 is 1.65.

  As described above, by using a thermosetting acrylic high refractive index resin, a thermosetting agent is required, but a photopolymerization initiator and other sensitizers can be eliminated, and alkali development characteristics and photocuring properties can be eliminated. Since the photolithography characteristics such as the above are not necessary, the green filter can be made thinner by increasing the pigment concentration.

  Next, a coating solution mainly composed of an acrylic photosensitive resin is spin-coated on the green resist layer 23 at a rotational speed of 3000 rpm, and then patterned by photolithography. As shown in FIG. A pattern 24 was formed. At this time, since the transparent resin serving as a mask can be selected from a resin that does not contain a substance that hinders resolution such as a pigment, patterning can be performed with high definition.

  Thereafter, using the transparent resin pattern 24 as a mask, the green resist layer 23 was etched using a chlorofluorocarbon gas in a dry etching apparatus, thereby forming a green filter pattern 25a as shown in FIG. . At this time, the film thickness of the green filter pattern 25a was 0.5 μm, and the first planarization layer 22 not covered with the green filter pattern 25a was completely removed.

  Thereafter, as shown in FIG. 5B, a blue filter pattern 25b and a red filter pattern (not shown) were sequentially formed by photolithography to obtain a color filter 26. At this time, the pigments used for the blue resist are C.I. I. PB15: 6, C.I. I. PV23, the pigment concentration is 30% by weight, the film thickness is 0.9 μm, the refractive index is 1.64, and the pigment used for the red resist is C.I. I. PR117, C.I. I. PR48: 1, C.I. I. PY139, the pigment concentration was 40% by weight, the film thickness was 0.9 μm, and the refractive index was 1.69.

  Further, on the color filter 26 formed in this manner, a coating solution containing an acrylic resin to which a UV absorber is added is spin-coated at a rotation speed of 1000 rpm, and subjected to a heat treatment at 200 ° C. for 10 minutes on a hot plate. The resin was cured to form a second planarization layer 27 as shown in FIG.

  Next, as shown in FIG. 5D, a lens matrix 28 made of an acrylic resin having photosensitivity and heat flow was formed on the planarizing layer 27 by a heat flow method that is a well-known technique.

  Finally, in a dry etching apparatus, an etching process is performed by using a fluorocarbon gas using the lens matrix 28 as a mask, and the shape of the lens matrix 28 is transferred to the second planarizing layer 27 to obtain a microlens. 29 was formed. At this time, it was removed to a depth of 0.1 μm from the surface of the boundary portion of each pattern of the color filter 26 to complete a solid-state imaging device as shown in FIG.

  In the manufacturing method of the solid-state imaging device as described above, the green filter pattern 25a is formed by using a pattern forming method by dry etching, so that a thin color filter having a fine pattern thickness can be obtained with a good shape and no residue. It was possible to form without pixel peeling. Moreover, since the thermosetting resin is used for the green filter layer, the concentration of the color material in the solid content can be increased, so that the color filter can be formed thin, and a thin solid-state imaging device can be obtained. .

  Further, in this embodiment, the first planarization layer 22 disposed under the color filter pattern formed by the photolithography pattern formation method is completely removed, but the green filter pattern formation matrix and The first planarizing layer may be left by adjusting the etching rate by selecting the thickness and material of the transparent resin pattern 24 to be formed. However, in order not to leave a residue of the color filter layer for the second and subsequent colors, it is preferable to remove them completely.

  Further, in this embodiment, the microlens is formed by dry etching, but the microlens may be formed by a conventional heat flow method. However, in order to reduce the thickness under the microlens, it is more preferable to form the microlens using a shape transfer technique by dry etching.

  In addition, the boundary part of adjacent color filters was etched at a depth of 0.1 μm from the surface, and the peripheral part of the microlens was made up of part of the color filter. The depth to be removed in the range of 0.03 μm to 0.5 μm from the surface can be set by selecting the material from the selection, the layer configuration of the layer to which the lens shape is transferred, the thickness, the etching rate, and the like. Here, the lower limit is set to 0.03 μm because it is the minimum value that can identify the film thickness by SEM or AFM, and the upper limit is set to 0.5 μm when dry etching is performed deeper than this. This is because the surface of the microlens is rough and the sensitivity is lowered due to surface scattering.

It is a fragmentary sectional view of the solid-state image sensor obtained by the manufacturing method concerning one embodiment of the present invention. It is sectional drawing which shows the manufacturing method of the solid-state image sensor which concerns on one Embodiment of this invention in process order. It is sectional drawing which shows the manufacturing method of the solid-state image sensor which concerns on one Embodiment of this invention in process order. FIG. 2 is a partial plan view of the solid-state image sensor shown in FIG. 1. It is sectional drawing which shows the manufacturing method of the solid-state image sensor which concerns on other embodiment of this invention in process order. It is process sectional drawing explaining the formation construction method patterned by the dry etching used by this invention. It is process sectional drawing explaining the formation construction method patterned by the photolithography used by this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10,20 ... Semiconductor substrate, 11, 21 ... Photoelectric conversion element, 12 ... Planarization layer, 13, 26 ... Color filter, 14, 29 ... Micro lens, 22 ... First planarization layer, 23 ... Green resist layer, 24 ... Resin pattern, 25a ... Green filter pattern, 25b ... Blue filter pattern, 27 ... Second planarization layer, 28 ... Lens matrix, 31, 41 ... Base material, 32, 42 ... Color filter layer, 33 ... Photosensitive resin layer 34... Resin pattern 35 and 43 Color filter pattern 42 a Light curing part 42 b Unnecessary part

Claims (13)

Two-dimensionally arranged photoelectric conversion elements on a semiconductor substrate, a color filter having a plurality of color filter patterns disposed on the semiconductor substrate corresponding to each of the photoelectric conversion elements, and the semiconductor substrate A method for producing a solid-state imaging device comprising a planarization layer formed on a part or all of the above,
The plurality of color filter patterns are formed by a forming method of patterning a predetermined color filter layer by dry etching and a forming method of patterning another color filter layer by photolithography,
Forming a color filter pattern formed at least first among the color filter patterns of the plurality of colors by dry-etching an unnecessary portion of the color filter layer and a flattening layer below the color filter layer; and other color filter patterns Having a process of patterning by photolithography ,
A method of manufacturing a solid-state imaging device, wherein a color filter pattern formed by the dry etching is in contact with another color filter pattern formed by the photolithography .   The forming method of patterning the predetermined color filter by dry etching is a method of dry etching until an unnecessary portion of the predetermined color filter layer and a planarizing layer thereunder reach a semiconductor substrate. Item 2. A method for manufacturing a solid-state imaging device according to Item 1.   3. The method of manufacturing a solid-state imaging device according to claim 1, wherein a color filter pattern having the widest area among the plurality of color filter patterns is patterned by dry etching.   The filter pattern of the plurality of colors includes a green filter pattern, a red filter pattern, and a blue filter pattern, and either or both of the green filter and the red filter are patterned by the dry etching. The manufacturing method of the solid-state image sensor of description.   The color filter layer patterned by the dry etching includes at least a thermosetting resin, and the color filter layer patterned by the photolithography includes at least a photocurable resin. 5. A method for producing a solid-state imaging device according to any one of 4 above. Two-dimensionally arranged photoelectric conversion elements on a semiconductor substrate, a color filter having a plurality of color filter patterns disposed on the semiconductor substrate corresponding to each of the photoelectric conversion elements, and the semiconductor substrate A solid-state imaging device comprising a planarization layer formed on a part or all of the above,
Said plural colors flattening layer below the color filter pattern of a certain color filter pattern formed by dry etching, and other color filter pattern formed by photolithography after forming the color filter patterns in by the dry etching Ri is Do different thickness between,
A solid-state imaging device , wherein a color filter pattern formed by the dry etching is in contact with another color filter pattern formed by the photolithography . Two-dimensionally arranged photoelectric conversion elements on a semiconductor substrate, a color filter having a plurality of color filter patterns disposed on the semiconductor substrate corresponding to each of the photoelectric conversion elements, and the semiconductor substrate A solid-state imaging device comprising a planarization layer formed on a part or all of the above,
The color filter includes a color filter pattern formed by dry etching formed on the semiconductor substrate through a planarization layer, and a color filter pattern formed directly by the dry etching, and then a photo filter. the color filter der with both other color filter pattern formed by lithography is,
A solid-state imaging device , wherein a color filter pattern formed by the dry etching is in contact with another color filter pattern formed by the photolithography . Two-dimensionally arranged photoelectric conversion elements on a semiconductor substrate, a color filter having a plurality of color filter patterns disposed on the semiconductor substrate corresponding to each of the photoelectric conversion elements, and the semiconductor substrate A solid-state imaging device comprising a planarization layer formed on a part or all of the above,
Among the plurality of color filter patterns, some of the color filter patterns include a thermosetting resin, and the remaining color filter patterns formed after forming the color filter pattern including the thermosetting resin are: a resin having a photocurable seen including,
A solid-state imaging device , wherein the color filter pattern containing the thermosetting resin is in contact with the color filter pattern containing the photocurable resin .   9. The multi-color filter pattern includes a green filter pattern, and a resin included in the green filter pattern has a higher refractive index than a resin included in another color filter pattern. The solid-state image sensor described in 1.   A microlens is disposed on the color filter directly or indirectly corresponding to each of the photoelectric conversion elements, and a peripheral portion of the microlens is configured by a part of the color filter. The solid-state imaging device according to claim 6, wherein the solid-state imaging device is provided. The film thickness of the color filter pattern formed by the dry etching is thinner than the film thickness of the color filter pattern formed by the photolithography, and the film thickness of the planarization layer under the color filter pattern formed by the dry etching. 11. The solid-state imaging device according to claim 6, wherein the solid-state imaging element is thicker than a film thickness of a planarizing layer under a color filter pattern formed by the photolithography. The solid-state imaging device according to claim 6, wherein the color filter pattern formed by the dry etching is a color filter pattern having the widest area among the filter patterns of the plurality of colors. The multi-color filter pattern includes a green filter pattern, a red filter pattern, and a blue filter pattern, and the color filter pattern formed by the dry etching is one or both of the green filter and the red filter. The solid-state imaging device according to claim 6.

Images