JP4857569B2 - Solid-state imaging device and manufacturing method thereof - Google Patents

Description

  The present invention relates to an image sensor represented by a photoelectric conversion element such as a C-MOS or CCD, and a method for manufacturing the same, and more particularly to a color filter formed corresponding to 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. .

  Further, the solid-state imaging device has a color filter paired with the photoelectric conversion device to achieve 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 of 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. Since the limited small opening portion leads to a decrease in sensitivity as it is, it is common to form a condensing microlens on the photoelectric conversion element in order 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. Insufficient 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 decreases, the aspect ratio increases (thickness relative to the width), so the portion that should be removed (the non-effective portion of the pixel) cannot be completely removed, leaving other residues. Adversely affects the color pixels. In order to remove the residue, a method such as extending the development time is performed. However, there is 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, the 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 this high-definition solid-state image sensor (that is, sensitivity reduction) and the 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 reduce the lens lower distance. When the lens 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. Second, in cameras using photoelectric conversion elements such as CMOS and 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.

  In general, a color filter is formed on a semiconductor substrate by forming a flattening layer on the semiconductor substrate in order to improve the adhesion to the base, and the above-described distance between the lenses is reduced, and the solid-state imaging device. In order to reduce the size, it is desirable to eliminate the planarization layer. However, since the color resist used in the photolithography process has poor adhesion to the semiconductor substrate and peels off during development, it is difficult to eliminate the planarization layer.

  In order to prevent such problems, it has been proposed to treat the surface of the semiconductor substrate with chemicals and introduce functional groups that easily bind to the resin to the surface of the semiconductor substrate. It was not possible to obtain sufficient adhesion.

On the other hand, the green resist has a low refractive index after curing due to the properties of the color material, compared with the red resist and the blue resist, and has been a problem in designing a solid-state imaging device. That is, it is difficult to select a color resist subjected to the photolithography process having a high refractive index after curing due to the restriction that photosensitivity is required. Due to the difference in refractive index, there is a problem that the light condensing effect by the microlens is different and 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, there is a problem that the distance between the color filter and the photoelectric conversion element and the distance between the microlens and the photoelectric conversion element (lens distance below) are large.

  The present invention has been made in view of the above-described problems, and is formed without causing a pattern shape defect or residue peeling. The distance from the photoelectric conversion element is small, and the reflectance varies between pixels. It is an object of the present invention to provide a solid-state imaging device including a color filter having no color and a manufacturing method thereof.

  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 for manufacturing a solid-state imaging device having a color filter comprising a plurality of color filter patterns, wherein the plurality of color filter patterns are formed by patterning a predetermined color filter layer by dry etching, and other color filter layers And a patterning method of patterning by photolithography, wherein at least the first color filter pattern of the plurality of color filter patterns is formed by dry etching, and the remaining color filter pattern is patterned by photolithography. A method for manufacturing a solid-state imaging device That.

  With dry etching, a resist for semiconductors with higher resolution than a color resist can be freely selected as a resin resist that serves as a mask. 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.

  According to a second aspect of the present invention, a photoelectric conversion element is two-dimensionally arranged on a semiconductor substrate, and a plurality of color filter patterns are arranged on the semiconductor substrate corresponding to each of the photoelectric conversion elements. A method of manufacturing a solid-state imaging device having a color filter, wherein the plurality of color filter patterns are formed by patterning a predetermined color filter layer by dry etching and patterning another color filter layer by photolithography. A solid-state imaging device manufacturing method is provided, wherein a color filter pattern having the widest area among the plurality of color filter patterns is patterned by dry etching.

  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.

  In the solid-state imaging device manufacturing method according to the first and second aspects of the present invention, the color filter can be directly formed on the semiconductor substrate. As described above, the distance under the lens can be reduced by eliminating the flattening layer conventionally formed on the semiconductor substrate.

  In addition, 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 filter provided by dry etching Since the color filter pattern provided by dry etching adjacent to the pattern serves as an anchor, it is possible to prevent the color filter pattern provided by the photolithography method from dropping off.

  According to a third aspect of the present invention, a photoelectric conversion element is two-dimensionally disposed on a semiconductor substrate, and a plurality of color filter patterns are disposed on the semiconductor substrate corresponding to the photoelectric conversion element. In the solid-state imaging device including a color filter, the plurality of color filter patterns include a predetermined color filter pattern including a thermoset resin and another color filter pattern including a photocured resin. An imaging device is provided.

  In the solid-state imaging device according to the third aspect of the present invention configured as described above, since the color filter has a color filter pattern including a thermoset resin, a semiconductor substrate without a planarizing layer Therefore, by forming directly on the semiconductor substrate, it is possible to obtain a solid-state imaging device having a small lens lower distance. In particular, since thermosetting resin is used, the concentration of the coloring material in the solid content can be increased, so that the color filter can be formed thinly, preventing color mixing of incident light, and the color filter and photoelectric conversion element. Can be obtained, and the distance below the microlens is small, and a solid-state imaging device with good sensitivity can be obtained. In addition, uneven color due to the shape of the pattern edge of the color filter can be eliminated.

  According to a fourth aspect of the present invention, a photoelectric conversion element is two-dimensionally disposed on a semiconductor substrate, and a plurality of color filter patterns are disposed on the semiconductor substrate corresponding to the photoelectric conversion element. In the solid-state imaging device having a color filter, the color filter pattern having the largest area among the filter patterns of the plurality of colors is a color filter pattern including a thermoset resin, and the other color filter patterns are photocured. Provided is a solid-state imaging device characterized by being a color filter pattern containing a resin.

  In the solid-state imaging device according to the fourth aspect of the present invention configured as described above, since the color filter pattern having the largest area contains a heat-cured resin, the adhesion with the semiconductor substrate is effectively maintained. can do. In addition, since the planarization layer can be eliminated, a solid-state imaging device with a small lens distance can be obtained. In particular, since the thermosetting resin is used, the concentration of the colorant in the solid content can be increased, so that the color filter can be formed thinly, preventing color mixing of incident light, and the color filter and photoelectric conversion element accordingly. Can be obtained, and the distance below the microlens is small, and a solid-state imaging device with good sensitivity can be obtained. In addition, uneven color due to the shape of the pattern edge of the color filter can be eliminated.

  When a color filter pattern is directly formed on a semiconductor substrate with a photo-curable resin (photoresist), the photoresist does not have sufficient adhesion to the semiconductor substrate, causing a problem of peeling during development. In the solid-state imaging device according to the fourth aspect, the heat-cured color filter pattern is adjacent to the heat-cured color filter pattern, and this heat-effect color filter pattern serves as an anchor, so that the photocured color filter pattern can be prevented from falling off. . Therefore, the color filter can be formed directly on the semiconductor substrate. Therefore, the distance between the color filter and the photoelectric conversion element and the distance between the microlens and the photoelectric conversion element (lens-under distance) can be reduced.

  The multi-color filter pattern includes a green filter pattern, and a resin included in the green filter pattern may have a higher refractive index than a resin included in another filter pattern. By doing so, the refractive indexes of the filter patterns of a plurality of colors can be approximated, and thereby the 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.

  Moreover, in order to eliminate the unevenness | corrugation of the said color filter surface, a planarization layer can be formed on a color filter and a micro lens can be formed on this planarization layer.

  Further, a microlens can be formed on the color filter, and the peripheral portion of the microlens can be constituted by a part of the color filter. With such a configuration, the distance below the microlens can be reduced, and a solid-state imaging device with good sensitivity can be obtained.

  According to the first aspect of the present invention, since at least the first pattern formation step is performed by patterning the color filter layer by dry etching, a semiconductor resist capable of high-definition patterning can be freely selected as a mask. Thus, there is provided a method for manufacturing a solid-state imaging device that makes it possible to form a color filter with a fine pattern in a good shape without residue and without causing pixel peeling. That is, in such a method, a predetermined color filter pattern with good adhesion can be formed first by dry etching the color filter layer that has been heat-cured, and then adjacent to it by photolithography. Even when other color filter patterns are formed, the color filter pattern having good adhesion formed first prevents peeling of adjacent color filter patterns. In addition, since the color filter pattern formed first is completely cured, it does not peel off in the subsequent photolithography development process.

  According to the second aspect of the present invention, since the color filter pattern with the largest area is formed by dry etching, a color filter with a fine pattern is formed in a good shape without residue and without pixel peeling. There is provided a method of manufacturing a solid-state imaging device that can be performed. That is, in such a method, the color filter pattern having the largest area can be formed with good adhesion by dry-etching the heat-cured color filter layer, so other adjacent color filter patterns can be formed. Even when formed by photolithography, peeling of adjacent color filter patterns is prevented because of the good adhesion of the color filter pattern having the largest area. In addition, since the color filter pattern having the largest area is completely cured, the color filter pattern is not peeled off in the development process of photolithography when other color filter patterns are formed.

  According to the third aspect of the present invention, since the color filter has a color filter pattern including a thermoset resin, the adhesion to the semiconductor substrate is achieved even if there is no planarization layer under the color filter pattern. Therefore, by forming directly on the semiconductor substrate, a solid-state imaging device having a small distance between the color filter and the photoelectric conversion element and a distance below the lens is provided. In particular, since a thermosetting resin is used, the concentration of the colorant in the solid content can be increased, so that the color filter can be formed thin, and the distance under the microlens is short, and the solid has good sensitivity. An image sensor can be obtained. In addition, uneven color due to the shape of the pattern edge of the color filter can be eliminated.

  According to the fourth aspect of the present invention, since the color filter pattern having the largest area contains a heat-cured resin, since the adhesion with the semiconductor substrate is good, the planarization layer can be eliminated. A solid-state imaging device having a small lower distance is provided. In particular, since the thermosetting resin is used, the concentration of the color material in the solid content can be increased, so that the color filter can be formed thin, and the distance between the color filter and the photoelectric conversion element and the microlens A solid-state imaging device with a short distance and good sensitivity can be obtained. In addition, uneven color due to the shape of the pattern edge of the color filter can be eliminated.

  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. And a color filter 12 for color-separating incident light, a flattening layer 13 for flattening the surface of the color filter 12, and a plurality of transfer lenses 14 arranged on the flattening layer 13. Note that the planarization layer 13 may not be provided depending on circumstances.

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

  First, as shown in FIG. 2B, a first color resist layer 22 is formed on a semiconductor substrate 20 (see FIG. 2A) having the photoelectric conversion elements 21 arranged two-dimensionally. The first color resist layer 22 is formed by applying a first resin dispersion liquid containing a thermosetting resin as a main component and having a pigment dispersed on the semiconductor substrate 20 and thermosetting it.

Next, as shown in FIG. 2B, a predetermined resin pattern 23 is formed on the first color resist layer 22 by photolithography, for example. As the resin pattern 23, for example,
As the resin pattern 23, for example, acrylic resin, epoxy resin, polyimide resin, phenol novolac resin, and other photosensitive resins can be used singly or as a mixture or copolymerized. 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 imaging devices that require high pixels and miniaturization. It is common.

Next, using the resin pattern 23 as a mask, the first color resist layer 22 is patterned by dry etching to form a first color filter pattern 24a as shown in FIG. As a dry etching method, for example, ECR, parallel plate magnetron, DRM, ICP, or two-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, after forming a second color resist layer on the entire surface, the second color resist layer is patterned by dry etching or photolithography in the same manner as the first color filter pattern 24a, as shown in FIG. 3B. Thus, the second color filter pattern 24b is formed.

  Next, after forming a third color resist layer on the entire surface, the third color resist layer is patterned by photolithography to form a third color filter pattern (not shown). A color filter 25 composed of a third color filter pattern is formed.

  FIG. 4 is a plan view showing the arrangement of the color filter patterns of the color filter 25. As shown in FIG. 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 planarizing layer 26 is formed on the color filter 25 formed as described above. As the planarizing layer, a resin containing one or more resins such as acrylic, epoxy, polyimide, phenol novolac, polyester, urethane, melamine, urea, and styrene can be used. Note that the planarization layer 26 is not necessarily provided.

  Finally, as shown in FIG. 3D, a microlens 27 is formed on the planarizing layer 26 by a heat flow method, which is a well-known technique, to complete a solid-state imaging device.

  In the manufacturing method of the solid-state imaging device described above, the first color filter pattern 24a is formed by patterning by dry etching after the first color resist layer 22 is completely thermoset, so that the semiconductor substrate Adhesion with 20 is very strong. By providing the first color filter pattern 24a with good adhesion in this way, even if the second and third color filter patterns are formed by photolithography, the second and third color filter patterns are: Since it is held by the adjacent first color filter pattern 24a, the adhesion of the color filter 25 is improved as a whole. Therefore, it can be formed directly on the semiconductor substrate 20 without providing a planarizing layer.

  In this case, it is desirable that the first color filter pattern 24a has the largest area among the color filter patterns of a plurality of colors. By doing so, adhesiveness with a semiconductor substrate can be strengthened more. The area of the color 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 the method according to the present embodiment, the green filter pattern can be formed by dry etching without depending on photolithography, so that the resin of the green filter pattern has a high refractive index among thermosetting resins. Can be selected widely.

  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.

  As another embodiment, as shown in FIG. 5, the microlens 27 is formed directly on the color filter 25, and the boundary portion of the adjacent filter pattern is removed from the surface to a depth of 0.03 μm to 0.5 μm. It can be a structure. In such a structure, since the peripheral portion of the microlens is constituted by a part of the color filter 25, 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 if a step exceeding 0.5 μm is formed, the film surface becomes rough and the sensitivity is reduced due to surface scattering. Further, at a step exceeding 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 A method for manufacturing a solid-state imaging device according to this example will be described with reference to FIGS. 2 and 3.

  As shown in FIG. 2A, a pigment-dispersed green resist is spin-coated at 1000 rpm on a semiconductor substrate 20 provided with two-dimensionally arranged photoelectric conversion elements 21 and then baked at 230 ° C. for 6 minutes. Then, as shown in FIG. 2B, a green resist layer 22 was 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 0.6 μm. Further, a thermosetting acrylic resin was used as the resin as the main component of the green resist.

  Next, a coating solution containing an acrylic photosensitive resin as a main component is spin-coated on the green resist layer 22 at a rotation speed of 3000 rpm, followed by patterning by photolithography. As shown in FIG. Formed. Thereafter, using the resin pattern 23 as a mask, the green resist layer 22 was etched using a chlorofluorocarbon gas in a dry etching apparatus to form a green filter pattern 24a as shown in FIG. The film thickness of the green filter pattern 24a at this time was 0.8 μm.

  Next, as shown in FIG. 3B, a blue filter pattern 24b was formed by a patterning method using dry etching in the same manner as the green filter pattern 24a using a pigment-dispersed blue resist. At this time, the pigments used for the blue resist are C.I. I. PB156, C.I. I. PV23 has a pigment concentration of 40% by weight and a film thickness of 0.8 μm. A thermosetting acrylic resin was used as the resin that is the main component of the blue resist.

  Thereafter, as shown in FIG. 3B, a red filter pattern (not shown) was formed by photolithography using a pigment-dispersed red resist to obtain a color filter 25. At this time, 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 45% by weight, and the film thickness was 0.8 μm.

  Further, a coating solution containing an acrylic resin is spin-coated at 1000 rpm on the color filter 25 formed in this manner, and heat treatment is performed at 200 ° C. for 10 minutes on a hot plate to cure the resin. As shown in FIG. 3C, the planarizing layer 26 was formed.

  Finally, as shown in FIG. 3D, a microlens 27 was formed on the planarizing layer 26 by a heat flow method, which is a well-known technique, to complete a solid-state imaging device.

  In the solid-state imaging device obtained as described above, the color filter 25 is directly formed on the surface of the semiconductor substrate 20, and since a thermosetting resin is used, the concentration of the color material in the solid content can be increased. As a result, the color filter 25 can be formed thin, and therefore the distance under the lens is small and the sensitivity is good. In addition, there was no uneven color due to the shape of the pattern edge of the color filter.

  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.

  Furthermore, by using a high refractive index resin for the green resist and setting the refractive index of the green filter pattern, red filter pattern, and blue filter pattern to the same level, surface reflection can be reduced and sensitivity is good. A solid-state imaging device can be obtained.

  In this embodiment, the green filter pattern and the blue filter pattern are formed by using a patterning technique by dry etching, and the red filter pattern is formed by photolithography. However, only the green filter pattern is formed by using a patterning technique by dry etching. The blue filter pattern and the red filter pattern may be formed by photolithography, or the green filter pattern and the red filter pattern may be formed by using a dry etching patterning technique, and the blue filter pattern may be formed by photolithography. May be. The color filter pattern formed first may be formed by dry etching, and the color filter pattern formed last may be formed by photolithography. However, since the green filter pattern and the blue filter pattern are more likely to be peeled off than the red filter pattern in the photolithography process, it is more preferable to form the green filter pattern and the blue filter pattern by a patterning technique using a dry etching technique.

  Furthermore, in the present embodiment, the microlens is formed by the heat flow method, but it is more preferable to form the microlens by using a dry etching patterning technique capable of forming a thickness below the microlens. This is done by forming a transparent resin layer that will eventually become a microlens on the color filter, then forming a microlens matrix (lens matrix) on it using a thermal flow method, and using the lens matrix as a mask for dry etching In this method, the shape of the lens matrix is transferred to the transparent resin layer. At this time, the boundary portion of the adjacent filter pattern is removed from the surface within the range of 0.03 μm to 0.5 μm by adjusting the etching rate by selecting the height of the lens mold used for transferring the lens shape and the material. However, it is preferable to form the peripheral portion of the microlens with a part of the color filter because the distance below the lens can be further reduced.

  In this embodiment, a thermosetting acrylic resin is used as the green resist resin, but it is also possible to use a radiation curing (photocuring) acrylic resin similar to the resin used for the red resist and the blue resist. is there. In this case, it is preferable to reduce the amount of monomers and photopolymerization initiators necessary for thinning, and more preferably a resin material similar to a thermosetting resin. In this case, the resin material is not suitable for the exposure / development process.

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 a fragmentary sectional view of the solid-state image sensing device concerning other embodiments of the present invention. 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, 25 ... Color filter, 13, 27 ... Microlens, 22 ... First color resist layer, 23 ... Resin pattern, 24a ... -1st color (green) filter pattern, 24b ... 2nd color (blue) filter pattern, 26 ... Flattening layer, 27 ... Microlens, 31, 41 ... Base material, 32, 42 ... Color Filter layer, 33 ... photosensitive resin layer, 34 ... resin pattern, 35, 43 ... color filter pattern, 42a ... photocuring part, 42b ... unnecessary part.

Claims (7)

A solid-state imaging device comprising: a photoelectric conversion element arranged two-dimensionally on a semiconductor substrate; and a color filter comprising a plurality of color filter patterns arranged on the semiconductor substrate corresponding to each of the photoelectric conversion elements A manufacturing method comprising:
The multi-color filter pattern is 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,
A method of manufacturing a solid-state imaging device, comprising: patterning at least a first color filter pattern of the plurality of color filter patterns by dry etching and patterning the remaining color filter patterns by photolithography. A solid-state imaging device comprising: a photoelectric conversion element arranged two-dimensionally on a semiconductor substrate; and a color filter comprising a plurality of color filter patterns arranged on the semiconductor substrate corresponding to each of the photoelectric conversion elements A manufacturing method comprising:
The multi-color filter pattern is 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,
A method of manufacturing a solid-state imaging device, wherein a color filter pattern having the widest area among the plurality of color filter patterns is patterned by dry etching. A solid-state imaging device comprising: a photoelectric conversion element arranged two-dimensionally on a semiconductor substrate; and a color filter comprising a plurality of color filter patterns arranged on the semiconductor substrate corresponding to each of the photoelectric conversion elements ,
The multi-color filter pattern includes a predetermined color filter pattern including a thermoset resin and another color filter pattern including a photocured resin. A solid-state imaging device comprising: a photoelectric conversion element arranged two-dimensionally on a semiconductor substrate; and a color filter comprising a plurality of color filter patterns arranged on the semiconductor substrate corresponding to each of the photoelectric conversion elements ,
Among the plurality of color filter patterns, the color filter pattern having the largest area is a color filter pattern including a thermoset resin, and the other color filter patterns are color filter patterns including a photocured resin. A solid-state imaging device.   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. Solid-state image sensor.   The solid-state imaging device according to claim 3, further comprising a planarization layer on the color filter.   A microlens further disposed on the color filter corresponding to each of the photoelectric conversion elements directly or indirectly, and a peripheral portion of the microlens is configured by a part of the color filter. The solid-state imaging device according to claim 3, wherein the solid-state imaging device is provided.

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