JP2010204154A - Method of manufacturing color filter and solid state imaging element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of inexpensively manufacturing a color filter having superior color reproducibility by restraining color mixture. <P>SOLUTION: In this method, a device protective layer 36 is formed on a chip substrate 12a. A recessed part 37 is formed on the device protective layer 36. A porous silica layer 74 is formed on the device protective layer 36 to fill in the recessed part 37. Green/blue/red openings 76R, 76G, 76B are formed in order in the porous silica layer 74, and green/blue/red layers 83G, 83B, 83R corresponding to the colors of the openings are stacked in order on the porous silica layer 74 to fill in the opening every time each opening is formed. The respective surfaces of the respective color layers 83R, 83B, 83G and the porous silica layer 74 are subjected to polishing until a polishing stopper part 38, which is a peripheral edge part of the recessed part 37, is exposed, thereby forming a color filter 22 including the respective color pixels 40R, 40G, 40B and separation walls 41. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a manufacturing method of a color filter for a solid-state imaging device or a liquid crystal display device, and a solid-state imaging device including a color filter manufactured by the manufacturing method.

  The solid-state imaging device is provided with a semiconductor substrate on which a light receiving element (photodiode) and a protective film are formed, and a color filter composed of a red pixel, a green pixel, and a blue pixel two-dimensionally arranged on the semiconductor substrate. ing. In recent years, the increase in the number of pixels of a solid-state image sensor has been remarkable, and the pixel size has been significantly reduced when compared with a solid-state image sensor having the same inch size as a conventional one. In addition, as the pixel size is reduced, the performance requirements for color separation become stricter. To maintain device characteristics such as color shading characteristics and color mixing prevention, the performance required for color filters includes thinning, rectangularization, and coloring. There is a demand for eliminating an overlap region in which colors overlap between pixels.

  As a method for producing such a color filter, a photolithographic method has been widely used. In the photolithography method, a colored photosensitive composition is applied and dried on a support to form a colored layer, and then the colored layer is subjected to pattern exposure, development, and baking to form a colored pixel of the first color (for example, green). In the same manner, the remaining colored pixels are formed. As the colored photosensitive composition, for example, an alkali-soluble resin containing a photopolymerizable monomer and a photopolymerization initiator is used. The photolithographic method can reduce initial investment because the manufacturing process conforms to the photolithographic process of semiconductor manufacturing, and is suitable for manufacturing color filters due to high-precision exposure and overlay accuracy of the photolithographic process. It is widely used as a new method.

  Incidentally, the light incident on the light receiving surface of the solid-state imaging device is not necessarily perpendicular to the light receiving surface and parallel to each other, and may be incident on the light receiving surface from an oblique direction. For this reason, when the colored pixels of the color filter are in contact with each other on the surface, when light is incident on the green pixel obliquely, for example, the light may leak from the green pixel to the adjacent blue pixel. As a result, an output from the photodiode is generated even though there is no incident light on the light receiving element corresponding to the blue pixel. That is, color mixing occurs.

  Further, in the photolithography method using a photosensitive composition, it is necessary to contain an alkali-soluble resin in a photosensitive curing component such as a photoinitiator and a monomer, and the content of the colorant in the total solid content is relatively As a result, there is a demerit that the film thickness increases. Moreover, since it has a photocurable component, the thickness of the composition affects the film thickness of the color filter, and it is difficult to realize a film thickness of 0.7 μm or less. As a result, color shading (color unevenness) is deteriorated and the above-mentioned color mixture is likely to occur.

  As a method for solving the problem of color mixture, for example, a method of providing a separation wall at the boundary of each color pixel of a color filter is well known so that light does not leak to adjacent color pixels. The separation wall is made of, for example, a low refractive material having a refractive index lower than that of each colored pixel, and reflects light incident from the colored pixel toward the original colored pixel (see Patent Document 1). As a method for solving the problem in the case of using the photolithographic method, a method of forming a color filter using a non-photosensitive material that does not contain a photocurable component is well known.

Patent Document 2 describes a method for manufacturing a color filter that can simultaneously solve the problems of color mixing and photolithography. In Patent Document 2, after forming a separation layer on a semiconductor substrate, the separation layer is dry-etched to form an opening corresponding to the first color pixel in the separation layer. Next, after forming a colored layer of the first color on the semiconductor substrate so as to fill the opening, chemical mechanical polishing (Chemical Mechanical Polishing) is performed on the surface of the colored layer of the first color until the surface of the separation layer is exposed. CMP) treatment is performed. Thereby, a colored pixel of the first color is formed in the opening. In the same manner, by repeating the steps of dry etching, colored layer formation, and CMP in the same manner, the remaining colored pixels are formed, and a separation wall is formed at the boundary of each colored pixel.
JP 2006-295125 A JP 2006-351775 A

  However, in the method described in Patent Document 2 in which each process of dry etching, colored layer formation, and CMP is repeated in order, for example, when forming an N color filter, it is necessary to repeat the CMP process N times. As a result, the number of processes increases.

  Further, when performing the CMP step, if the polishing rate of the separation layer is substantially the same as the polishing rate of each colored layer, or higher than the polishing rate of each colored layer, there is a risk that each colored layer will be excessively shaved. is there. As a result, when the thickness of each colored pixel becomes thinner than a desired thickness, the amount of light transmitted through each colored pixel may change, and the optical characteristics of the color filter may change. In order to prevent this, a method of forming a polishing stopper layer having a low polishing rate on the separation layer and using this polishing stopper layer for end point detection of CMP can be considered, but in this case, in order to form a color filter Since the types of necessary materials increase, there arises a problem that costs increase.

  The present invention has been made to solve the above problems, and a color filter manufacturing method for manufacturing a color filter that suppresses color mixing and has excellent color reproducibility at low cost, and a color filter manufactured by this manufacturing method. It aims at providing a solid-state image sensor provided with.

  In order to achieve the above object, a color filter manufacturing method of the present invention is provided at a boundary between a plurality of colored pixels arranged two-dimensionally on a protective layer protecting the surface of a substrate and the different colored pixels. In the method for producing a color filter comprising a separation wall, a protective layer forming step for forming the protective layer on the substrate, a concave portion forming step for forming a concave portion in the protective layer, and at least the concave portion on the protective layer Forming a material layer for forming the separation wall so as to fill a gap, and forming an opening so as to leave a portion to be the separation wall by etching the material layer on the recess. And a colored solid layer forming step of forming a colored solid layer on the material layer so as to fill the opening, and the opening forming step and the colored solid layer forming step are alternately repeated a plurality of times to obtain the material. In order to form the openings corresponding to the colored pixels of the plurality of colors in order, and to fill the openings every time the openings are formed, the colored solid layer corresponding to the openings A repeating step of sequentially laminating on the material layer, and after the repeating step, until the peripheral portion of the concave portion of the protective layer is exposed, each surface of the colored solid layer and the material layer is subjected to a planarization treatment, A flattening treatment step of forming the plurality of colored pixels and the separation wall on the concave portion.

  The separation wall is preferably formed of a material having a refractive index lower than that of the colored pixels of the plurality of colors. Moreover, the said separation wall can use a porous silica suitably. Thereby, since light leakage from a certain colored pixel to an adjacent colored pixel with a separation wall interposed therebetween is prevented, the occurrence of color mixing can be suppressed.

  The separation wall preferably has a line width of 0.05 μm or more and 0.20 μm or less in a direction orthogonal to the film thickness direction of the material layer. As a result, it is possible to achieve both prevention of color mixing (0.05 μm or more) and an increase in the area ratio of each color pixel to the entire region of the color filter (0.20 μm or less).

  The planarization process is preferably performed by a chemical mechanical polishing process.

  The recess forming step is preferably performed by a dry etching method. The opening forming step is preferably performed by a dry etching method. By using the dry etching method, for example, the pattern cross section can be formed in a more rectangular shape than when wet etching is performed.

  A solid-state imaging device according to the present invention includes a color filter manufactured by the method for manufacturing a color filter according to any one of claims 1 to 7.

  The color filter manufacturing method and solid-state imaging device according to the present invention include a first step of forming a protective layer on a substrate, a second step of forming a concave portion 37 in the protective layer, and a protective layer so as to fill the concave portion. A third step of forming a material layer thereon, a fifth step of forming an opening in the material layer, a sixth step of forming a colored solid layer on the material layer so as to fill the opening, and a fifth step Step 6 and Step 6 are alternately repeated, and a colored solid layer is sequentially laminated on the material layer so as to fill the opening every time the opening is formed, and the peripheral edge of the concave portion of the protective layer Since the color filter having the separation layer is manufactured through the seventh step of flattening each surface of each colored solid layer and the material layer until the portion is exposed, the peripheral portion of the recess is a polishing stopper. To act as Door can be. For this reason, it is not necessary to separately form a polishing stopper, so that the number of materials necessary for forming the color filter can be reduced. In addition, the number of executions of the flattening process can be reduced to one. As a result, it is possible to manufacture a color filter that suppresses color mixing and has excellent color reproducibility at low cost.

  In the present invention, the color filter is formed in the concave portion of the protective layer, and the surface of the color filter and the surface of the protective layer are flattened by the flattening treatment. Are equal. For this reason, the film thickness of a color filter can be easily adjusted by adjusting the depth of a recessed part.

It is sectional drawing of a solid-state imaging device. It is sectional drawing of the imaging part of a solid-state image sensor. It is sectional drawing of a color filter and a device protective layer. It is a flowchart of a solid-state image sensor formation process. It is explanatory drawing for demonstrating the device protective layer formation process of FIG. It is explanatory drawing for demonstrating the photoresist layer formation process of the recessed part formation process of FIG. It is explanatory drawing for demonstrating the exposure * PEB * image development / baking process of the recessed part formation process. It is explanatory drawing for demonstrating the dry etching process of the recessed part formation process. It is explanatory drawing for demonstrating the porous silica layer formation process of FIG. It is explanatory drawing for demonstrating the photoresist layer formation process of the opening part for green of FIG. It is explanatory drawing for demonstrating the exposure * PEB * image development / baking process of the opening part formation process for the green. It is explanatory drawing for demonstrating the dry etching process of the dry etching and peeling process of the opening part for green. It is explanatory drawing for demonstrating the peeling process of the dry etching and peeling process. It is the enlarged view to which the opening part for green of FIG. 13 was expanded. It is explanatory drawing for demonstrating the green layer formation process of FIG. It is explanatory drawing for demonstrating the photoresist layer formation process of the opening part for blue of FIG. It is explanatory drawing for demonstrating the exposure, PEB, image development, and baking process of the opening part formation process for the blue. It is explanatory drawing for demonstrating the dry etching and peeling process of the opening part formation process for the blue. It is explanatory drawing for demonstrating the blue layer formation process of FIG. It is explanatory drawing for demonstrating the photoresist layer formation process of the opening part for red of FIG. It is explanatory drawing for demonstrating the exposure * PEB * image development / baking process of the opening part formation process for the said red. It is explanatory drawing for demonstrating the dry etching and peeling process of the opening part formation process for the said red. It is explanatory drawing for demonstrating the red layer formation process of FIG. It is explanatory drawing for demonstrating the CMP process of FIG. It is a top view of a color filter.

  As shown in FIG. 1, the solid-state imaging device 9 includes a rectangular solid-state imaging element 10 and a transparent cover glass 11 that is held above the solid-state imaging element 10 and seals the solid-state imaging element 10.

  The solid-state imaging device 10 photoelectrically converts an optical image formed on the imaging unit 10a serving as the light receiving surface, and outputs it as an image signal. The solid-state imaging device 10 includes a laminated substrate 12 in which two substrates are laminated. The laminated substrate 12 includes a rectangular chip substrate 12a and a circuit substrate 12b having the same size, and the circuit substrate 12b is laminated on the back surface of the chip substrate 12a.

  The kind of the substrate used as the chip substrate 12a is not particularly limited, and it is used for soda glass, borosilicate glass, quartz glass and the like in which a transparent conductive film is attached to a liquid crystal display device or the like, a solid-state imaging device, or the like. A photoelectric conversion element substrate such as a silicon substrate, an oxide film, or silicon nitride is used.

  An imaging unit 10a is provided at the center of the surface of the chip substrate 12a. A plurality of electrode pads 17 are provided on the surface edge of the chip substrate 12a. The electrode pad 17 is electrically connected to the imaging unit 10a via a signal line (not shown) provided on the surface of the chip substrate 12a (which may be a bonding wire).

  External connection terminals 18 are provided on the back surface of the circuit board 12b at positions substantially below the electrode pads 17 described above. Each external connection terminal 18 is connected to an electrode pad 17 via a through electrode 19 that vertically penetrates the multilayer substrate 12. Further, each external connection terminal 18 is connected to a control circuit that controls driving of the solid-state imaging device 10 and an image processing circuit that performs image processing on an imaging signal output from the solid-state imaging device 10 via a wiring (not shown). Has been.

  As shown in FIG. 2, the imaging unit 10 a is configured by each unit provided on a semiconductor substrate 25 such as a light receiving element 21, a color filter 22, a microlens 23. In FIG. 2 (the same applies to the other drawings), in order to clarify each part, the ratio of the thickness and the width is disregarded and a part is exaggerated.

  As the semiconductor substrate 25, various known substrates similar to the aforementioned chip substrate 12a are used. A p-well layer 26 is formed on the surface layer of the semiconductor substrate 25. In the p-well layer 26, light receiving elements 21 made of n-type layers and generating and storing signal charges by photoelectric conversion are arranged in a square lattice shape (or a honeycomb shape).

On one side of the light receiving element 21, a vertical transfer path 28 made of an n-type layer is formed via a read gate portion 27 on the surface layer of the p-well layer 26. Further, a vertical transfer path 28 belonging to an adjacent pixel is formed on the other side of the light receiving element 21 via an element isolation region 29 made of a p ⁺ type layer. The read gate unit 27 is a channel region for reading signal charges accumulated in the light receiving element 21 to the vertical transfer path 28.

  A gate insulating film 31 made of an ONO (Oxide-Nitride-Oxide) film is formed on the surface of the semiconductor substrate 25. A vertical transfer electrode 32 made of polysilicon or amorphous silicon is formed on the gate insulating film 31 so as to cover the vertical transfer path 28, the read gate portion 27, and the element isolation region 29. The vertical transfer electrode 32 functions as a drive electrode that drives the vertical transfer path 28 to perform charge transfer, and a read electrode that drives the read gate unit 27 to read signal charges. The signal charges are sequentially transferred from the vertical transfer path 28 to a horizontal transfer path (not shown) and an output unit (floating diffusion amplifier), and then output as a voltage signal.

  A light shielding film 34 made of tungsten or the like is formed on the vertical transfer electrode 32 so as to cover the surface thereof. The light shielding film 34 has an opening at a position directly above the light receiving element 21 and shields light from other regions. On the light shielding film 34, an insulating film 35 made of BPSG (borophosphosilicate glass), a device protective layer (also called a passivation film) 36 made of P-SiN, which corresponds to the protective layer of the present invention, and the like are provided. .

The device protection layer 36 is a film for protecting the surface of the semiconductor substrate 25 on which the light receiving element 21 and the like are formed from external damage. The light receiving element 21 is protected from mechanical damage, chemical damage, electrical damage, and the like. Protect etc. The device protection layer 36 is formed of silicon nitride (Si ₃ N ₄ ) or the like using a CVD method or the like at a high temperature (for example, 500 to 800 ° C.). Examples of the device protective layer 36 include silicon oxide (SiO ₂ ), glass (PSG), polyimide and the like, in addition to silicon nitride. In particular, silicon nitride suppresses impurity diffusion, suppresses ingress of ions, and has high moisture resistance. Is particularly preferred.

  As shown in FIG. 3, a substantially rectangular recess 37 is formed in the device protection layer 36 as a color filter 22 formation region (colored pixel formation region). For this reason, the device protective layer 36 is formed so that the thickness of the portion other than the concave portion 37 is larger than the thickness of the color filter 22. The device (imaging unit 10a) can be thinned by forming the device protective film 36 as thin as possible to ensure device reliability.

  The film thickness of the thinnest part of the device protective layer 36 (the lower part of the recess 37) is preferably 0.10 μm or more. The film thickness of the thinnest part is more preferably 0.15 μm or more, particularly preferably 0.20 μm or more, from the viewpoint of ensuring the function as the device protective layer. In addition, in order to suppress the thickness of the solid-state image sensor 10, it is preferable that it is 0.5 micrometer or less.

  The peripheral edge portion of the concave portion 37 of the device protective film 36 becomes a polishing stopper portion 38 when the color filter 22 is formed (at the time of CMP processing). That is, the device protective film 36 can have a function as a polishing stopper.

  The color filter 22 is formed so that the surface thereof is substantially flush with the device protection layer 36. In the following description, the colored solid layer (film) formed on the semiconductor substrate 25 without dividing the region is referred to as a “colored (red, green, blue) layer”, and the elements constituting the color filter 22 It is called “colored (red, green, blue) pixels”.

  Returning to FIG. 2, the color filter 22 includes a plurality of transmissive colored pixels of two-dimensional arrangement, specifically, a red pixel 40R, a blue pixel 40B, and a green pixel 40G. Each of the color pixels 40R, 40G, and 40B is formed above the light receiving element 21. The green pixels 40G are formed in a checkered pattern, and the red pixels 40R and the blue pixels 40B are formed between the green pixels 40G (see FIG. 25). 2 to 24, the color pixels 40R, 40G, and 40B are displayed in a line in order to explain that the color filter 22 includes three colored pixels.

  Each of the color pixels 40R, 40G, and 40B is formed of a known colored composition that does not include a photosensitive component (photolithographic component), for example, a colored thermosetting composition. This eliminates the need to contain a photosensitive component in the material (composition) of each of the color pixels 40R, 40G, and 40B, so that the color material ratio in the solid content can be increased and the color filter 22 can be made thin. it can. When the color filter 22 is thinned, the transmission amount of the oblique light component can be reduced, and the color shading characteristics are improved. In addition, since the thickness can be reduced, the device can be reduced in size.

  Separation walls 41 are formed at the boundaries between the color pixels 40R, 40G, and 40B to separate the color pixels 40R, 40G, and 40B from each other and prevent color mixing of the colors. The separation wall 41 is formed by a dry etching method so that the wall surface thereof is substantially parallel to the normal direction of the chip substrate 12a. For this reason, each color pixel 40R, 40G, 40B is formed in a rectangular cross section without rounding corners.

  The separation wall 41 is a low refractive index layer (light reflecting layer) formed of a low refractive material having a lower refractive index than the respective color pixels 40R, 40G, and 40B. When oblique light is incident from adjacent colored pixels, Is reflected toward the original colored pixel. Since the refractive indexes of the color pixels 40R, 40G, and 40B are 1.55 to 1.65, the refractive index n of the separation wall 41 (low refractive index material) is set to n ≦ 1.5, whereby each color pixel 40R. , 40G, and 40B can be provided with a difference in refractive index. The refractive index n of the separation wall 41 is more preferably 1.45 or less, and most preferably 1.4 or less from the viewpoint of obtaining a larger refractive index difference from the color pixels 40R, 40G, and 40B.

  Examples of the low refractive material include glass (n = 1.52), fluorine-based polymer (n = 1.3 to 1.4), and siloxane polymer (n = 1.5). Examples of the fluorine-based polymer include Opstar low refractive index material JN series manufactured by JSR, and examples of the siloxane polymer include NR and LS series manufactured by Toray Industries, Inc. In the present invention, porous silica is used.

Porous silica [porous layer of SiO ₂ film (silica; n = 1.21 to 1.35)] is generally referred to as a low-k agent. A low-k agent is a material having a low dielectric constant used as an interlayer insulating material for supporting LSI wiring, and has a feature of a low refractive index in addition to the performance of a low dielectric constant. A low-k agent can reduce the dielectric constant (k) and refractive index of a material by containing a large number of extremely fine pores (depletion), but has a low mechanical strength. For this reason, the Low-k agent is easy to process because it has a lower resistance to CMP than an SOG (Spin On Glass) film typified by a siloxane polymer. For the Low-k agent of the present invention, SOD (Spin On Dielectric: coating type) can be preferably used.

  Thus, the separation wall 41 can be made into a light reflection layer by forming the separation wall 41 with porous silica. For example, when oblique light is incident on the green pixel 40, a part of the incident light is transmitted through the green pixel 40G, but the rest is about to leak into the adjacent blue pixel 40B. The light that is about to leak out is totally reflected by the separation wall 41 when the incident angle with respect to the separation wall 41 is greater than or equal to the critical angle, so that light leakage to the blue pixel 40B is suppressed.

  In addition, the amount of light transmitted through the green pixel 40G increases because the light that is about to leak is totally reflected on the green pixel 40G. That is, since a lens effect is obtained in each of the color pixels 40R, 40G, and 40B, each of the color pixels 40R, 40G, and 40B (color filter 22) can function as a condensing unit. Thereby, it is possible to prevent color mixing and increase the sensitivity of the light receiving element 21 by increasing transmitted light.

  A line width (hereinafter simply referred to as a line width) in a direction orthogonal to the thickness direction of the color filter 22 of the separation wall 41 is formed to be 0.05 μm or more and 0.2 μm or less. When the line width of the separation wall 41 is within the above-described range (0.02 μm or less), the area ratio of the color pixels 40R, 40G, and 40B to the entire region of the color filter 22 can be increased. The color purity of 40G and 40B can be improved. Moreover, if the line width of the separation wall 41 is 0.05 μm or more, it can function as a low refractive index layer. The thickness of the separation wall 41 is preferably 0.08 μm or more and 0.15 μm or less.

  The planarization film 42 is formed so as to cover the upper surface of the color filter 22 and has a flat upper surface. The micro lens 23 is a lens provided with the convex surface upward, and is provided on the upper surface of the planarizing film 42 and above each light receiving element 21. Each micro lens 23 efficiently guides light from the subject to each light receiving element 21. Note that an imaging device having a photoelectric conversion layer immediately below the color filter layer (for example, an element having a panchromatic organic photoelectric conversion film) has a close distance between the color filter and the photoelectric conversion layer and a large opening area of the photoelectric conversion layer. Therefore, the light collection efficiency is not deteriorated even if the upper layer of the color filter does not have a microlens. The present invention can also be applied to such a structure.

[Red / Green / Blue Thermosetting Composition]
Next, the non-photosensitive colored thermosetting composition (red / blue / green thermosetting composition) that is a material of each of the color pixels 40R, 40G, and 40B will be described. The red / green / blue thermosetting composition contains a colorant and a thermosetting compound, and the colorant concentration in the total solid content is preferably 30% by mass or more and less than 100% by mass. By increasing the colorant concentration, a thinner color filter can be formed.

<Colorant>
The colorant is not particularly limited, and various conventionally known dyes and pigments can be used alone or in combination.

  Examples of the pigment include conventionally known various inorganic pigments or organic pigments. Further, considering that it is preferable to have a high transmittance, whether it is an inorganic pigment or an organic pigment, it is preferable to use a pigment having an average particle size as small as possible, and considering the handling properties, the average particle size of the pigment is 0.01 μm to 0.1 μm is preferable, and 0.01 μm to 0.05 μm is more preferable.

  The following can be mentioned as such a pigment. However, the present invention is not limited to these.

C. I. Pigment yellow 11,24,108,109,110,138,139,150,151,154,167,180,185;
C. I. Pigment orange 36, 71;
C. I. Pigment red 122,150,171,175,177,209,224,242,254,255,264;
C. I. Pigment violet 19, 23, 32;
C. I. Pigment blue 15: 1, 15: 3, 15: 6, 16, 22, 60, 66;
C. I. Pigment Green 7, 36, 58
C. I. Pigment Black 1, Carbon Black

  In the present invention, when the colorant is a dye, the dye can be uniformly dissolved in the composition to obtain a non-photosensitive colored thermosetting resin composition. There is no restriction | limiting in particular as such a dye, A well-known dye can be used for color filters.

  The chemical structure is pyrazole azo, anilino azo, triphenyl methane, anthraquinone, anthrapyridone, benzylidene, oxonol, pyrazolotriazole azo, pyridone azo, cyanine, phenothiazine, pyrrolopyrazole azomethine, Xanthene-based, phthalocyanine-based, benzopyran-based and indigo-based dyes can be used.

  The colorant content in the total solid content of the colored thermosetting composition is not particularly limited, but is preferably 30% by mass or more and less than 100% by mass, and more preferably 50 to 80% by mass. By setting the content to 30% by mass or more, an appropriate chromaticity as a color filter can be obtained. Moreover, hardening can fully be advanced by setting it as less than 100 mass%, and the strength reduction as a film | membrane can be suppressed.

<Thermosetting compound>
The thermosetting compound is not particularly limited as long as the film can be cured by heating. For example, a compound having a thermosetting functional group can be used. As such a thermosetting compound, for example, a compound having at least one group selected from an epoxy group, a methylol group, an alkoxymethyl group, and an acyloxymethyl group is preferable.

  More preferable thermosetting compounds include (a) an epoxy compound, (b) a melamine compound, a guanamine compound, and a glycoluril substituted with at least one substituent selected from a methylol group, an alkoxymethyl group, and an acyloxymethyl group. Examples thereof include a compound or a urea compound, (c) a phenol compound, a naphthol compound or a hydroxyanthracene compound substituted with at least one substituent selected from a methylol group, an alkoxymethyl group and an acyloxymethyl group. Among these, a polyfunctional epoxy compound is particularly preferable as the thermosetting compound.

  (A) As an epoxy compound, as long as it has an epoxy group and has crosslinkability, any may be sufficient, for example, bisphenol A diglycidyl ether, ethylene glycol diglycidyl ether, butanediol diglycidyl ether, Divalent glycidyl group-containing low molecular weight compounds such as hexanediol diglycidyl ether, dihydroxybiphenyl diglycidyl ether, diglycidyl phthalate, and N, N-diglycidyl aniline; similarly, trimethylolpropane triglycidyl ether, trimethylol Trivalent glycidyl group-containing low molecular weight compounds typified by phenol triglycidyl ether, TrisP-PA triglycidyl ether, etc .; similarly, pentaerythritol tetraglycidyl ether, tetramethylol bis Tetravalent glycidyl group-containing low molecular weight compounds represented by enol A tetraglycidyl ether and the like; similarly, polyvalent glycidyl group-containing low molecular weight compounds such as dipentaerythritol pentaglycidyl ether and dipentaerythritol hexaglycidyl ether; And glycidyl group-containing polymer compounds represented by 1,2-epoxy-4- (2-oxiranyl) cyclohexane adduct of 2,2-bis (hydroxymethyl) -1-butanol and the like. .

  Commercially available products include alicyclic epoxy compounds: “CEL-2021”, etc., alicyclic solid epoxy resins: “EHPE-3150”, etc., epoxidized polybutadiene: “PB3600”, etc. Ring epoxy compound: etc. "CEL-2081", lactone modified epoxy resin: "PCL-G" etc. are mentioned (all are Daicel Chemical Industries Ltd. make). Other examples include “Celoxide 2000”, “Epolide GT-3000”, “GT-4000” (all manufactured by Daicel Chemical Industries, Ltd.), and the like. Among these, the alicyclic solid epoxy resin has the best curability, and “EHPE-3150” has the best curability. These compounds may be used alone or in combination of two or more, and combinations with other types shown below are also possible.

  The number of methylol groups, alkoxymethyl groups, and acyloxymethyl groups contained in (b) above is substituted with 2-6 in the case of melamine compounds, in the case of glycoluril compounds, guanamine compounds, urea compounds. Although it is 2-4, Preferably it is 5-6 in the case of a melamine compound, and 3-4 in the case of a glycoluril compound, a guanamine compound, and a urea compound. Hereinafter, the melamine compound, the guanamine compound, the glycoluril compound, and the urea compound in (b) are collectively referred to as a compound (containing a methylol group, an alkoxymethyl group, or an acyloxymethyl group) in (b).

  The methylol group-containing compound in (b) can be obtained by heating the alkoxymethyl group-containing compound in (b) in the presence of an acid catalyst such as hydrochloric acid, sulfuric acid, nitric acid, methanesulfonic acid or the like in alcohol. The acyloxymethyl group-containing compound in (b) can be obtained by mixing and stirring the methylol group-containing compound in (b) with acyl chloride in the presence of a basic catalyst.

  Hereinafter, specific examples of the compound in (b) having the substituent will be given. Examples of the melamine compound include hexamethylol melamine, hexakis (methoxymethyl) melamine, a compound in which 1 to 5 methylol groups of hexamethylol melamine are methoxymethylated, or a mixture thereof, hexakis (methoxyethyl) melamine, hexakis (acyloxymethyl) ) A compound in which 1 to 5 methylol groups of melamine and hexamethylolmelamine are acyloxymethylated, or a mixture thereof, and the like.

  Examples of the guanamine compound include tetramethylolguanamine, tetrakis (methoxymethyl) guanamine, a compound obtained by methoxymethylating 1 to 3 methylol groups of tetramethylolguanamine or a mixture thereof, tetrakis (methoxyethyl) guanamine, tetrakis (acyloxymethyl) ) A compound obtained by acyloxymethylating 1 to 3 methylol groups of guanamine and tetramethylolguanamine, or a mixture thereof.

  Examples of the glycoluril compound include tetramethylol glycoluril, tetrakis (methoxymethyl) glycoluril, a compound obtained by methoxymethylating 1 to 3 methylol groups of tetramethylol glycoluril or a mixture thereof, and a methylol group of tetramethylol glycoluril. Of 1 to 3 are acyloxymethylated or a mixture thereof.

  Examples of the urea compound include tetramethylol urea, tetrakis (methoxymethyl) urea, a compound obtained by methoxymethylating 1 to 3 methylol groups of tetramethylolurea or a mixture thereof, tetrakis (methoxyethyl) urea, and the like.

  In addition, the compounds in (b) may be used alone or in combination.

  The compound in (c), that is, the phenol compound, naphthol compound or hydroxyanthracene compound substituted with at least one group selected from a methylol group, an alkoxymethyl group and an acyloxymethyl group is the compound in (b) above. As in the case of, the intermixing with the overcoated photoresist is suppressed and the film strength is further increased. Hereinafter, these compounds may be collectively referred to as a compound (containing a methylol group, an alkoxymethyl group or an acyloxymethyl group) in (c).

  The number of methylol groups, acyloxymethyl groups or alkoxymethyl groups contained in the compound in (c) is at least 2 per molecule, and from the viewpoint of thermosetting and storage stability, Compounds in which the 2-position and 4-position are all substituted are preferred. In addition, the naphthol compound and hydroxyanthracene compound serving as the skeleton are also preferably compounds in which all of the ortho-position and para-position of the OH group are substituted. The 3-position or 5-position of the phenol compound may be unsubstituted or may have a substituent. Also in the naphthol compound, except for the ortho position of the OH group, it may be unsubstituted or may have a substituent.

  The methylol group-containing compound in (c) uses, as a raw material, a compound in which the 2-position or 4-position of the phenolic OH group is a hydrogen atom, and this is used as sodium hydroxide, potassium hydroxide, ammonia, tetraalkylammonium hydroxide, etc. It can be obtained by reacting with formalin in the presence of a basic catalyst. The alkoxymethyl group-containing compound in (c) can be obtained by heating the methylol group-containing compound in (c) in the presence of an acid catalyst such as hydrochloric acid, sulfuric acid, nitric acid, methanesulfonic acid, etc. in alcohol. Further, the acyloxymethyl group-containing compound in (c) can be obtained by reacting the methylol group-containing compound in (c) with an acyl chloride in the presence of a basic catalyst.

  Examples of the skeletal compound in (c) include phenol compounds, naphthols, hydroxyanthracene compounds, etc., in which the ortho-position or para-position of the phenolic OH group is unsubstituted. For example, phenol, cresol isomers, 2, 3 -Bisphenols such as xylenol, 2,5-xylenol, 3,4-xylenol, 3,5-xylenol and bisphenol A; 4,4'-dihydroxybiphenyl, TrisP-PA (Honshu Chemical Industry Co., Ltd.) Manufactured), naphthol, dihydroxynaphthalene, 2,7-dihydroxyanthracene, and the like.

  Examples of the phenol compound in the above (c) include trimethylolphenol, tris (methoxymethyl) phenol, a compound obtained by methoxymethylating one or two methylol groups of trimethylolphenol, trimethylol-3-cresol, tris. (Methoxymethyl) -3-cresol, a compound obtained by methoxymethylating one or two methylol groups of trimethylol-3-cresol, dimethylol cresol such as 2,6-dimethylol-4-cresol, tetramethylol bisphenol A, Tetrakis (methoxymethyl) bisphenol A, compounds obtained by methoxymethylating 1 to 3 methylol groups of tetramethylol bisphenol A, tetramethylol-4,4′-dihydroxybiphenyl, tetrakis (methoxymethyl) -4 4'-dihydroxybiphenyl, hexamethylol form of TrisP-PA, hexakis (methoxymethyl) form of TrisP-PA, compound obtained by methoxymethylating 1 to 5 methylol groups of hexamethylol form of TrisP-PA, bis (hydroxy Methyl) naphthalenediol, and the like.

  In addition, examples of the hydroxyanthracene compound include 1,6-dihydroxymethyl-2,7-dihydroxyanthracene, and examples of the acyloxymethyl group-containing compound include a part of the methylol group of the methylol group-containing compound, or Examples include compounds that are all acyloxymethylated.

  Among these compounds, preferred are trimethylolphenol, bis (hydroxymethyl) -p-cresol, tetramethylolbisphenol A, TrisP-PA (Honshu Chemical Co., Ltd.) hexamethylol, or their Examples include phenol compounds in which a methylol group is substituted with an alkoxymethyl group and both a methylol group and an alkoxymethyl group.

  These compounds in (c) may be used alone or in combination.

  Although the total content of the thermosetting compound in the thermosetting composition varies depending on the material, it is preferably 0.1 to 50% by mass with respect to the total solid content (mass) of the curable composition. 2 to 40% by mass is more preferable, and 1 to 35% by mass is particularly preferable.

<Various additives>
In the thermosetting composition, various additives such as a binder, a curing agent, a curing catalyst, a solvent, a filler, a polymer compound other than the above, and an interface are added as necessary as long as the effects of the present invention are not impaired. An activator, an adhesion promoter, an antioxidant, an ultraviolet absorber, an aggregation inhibitor, a dispersant, and the like can be blended.

<Binder>
The binder is often added at the time of preparing the pigment dispersion, does not require alkali solubility, and may be soluble in an organic solvent.

  The binder is preferably a linear organic polymer that is soluble in an organic solvent. Examples of such linear organic high molecular polymers include polymers having a carboxylic acid in the side chain, such as JP-A-59-44615, JP-B-54-34327, JP-B-58-12577, and JP-B-54-. No. 25957, JP-A-59-53836, JP-A-59-71048, methacrylic acid copolymer, acrylic acid copolymer, itaconic acid copolymer, crotonic acid copolymer, etc. Examples thereof include polymers, maleic acid copolymers, partially esterified maleic acid copolymers, and acidic cellulose derivatives having a carboxylic acid in the side chain are also useful.

  Among these various binders, from the viewpoint of heat resistance, polyhydroxystyrene resins, polysiloxane resins, acrylic resins, acrylamide resins, and acrylic / acrylamide copolymer resins are preferable. Acrylic resins, acrylamide resins, and acrylic / acrylamide copolymer resins are preferred.

  Examples of the acrylic resin include copolymers comprising monomers selected from benzyl (meth) acrylate, (meth) acrylic acid, hydroxyethyl (meth) acrylate, (meth) acrylamide, and the like, such as benzyl methacrylate / methacrylic acid. Each copolymer such as benzylmethacrylate / benzylmethacrylamide, KS resist-106 (manufactured by Osaka Organic Chemical Industry Co., Ltd.), cyclomer P series (manufactured by Daicel Chemical Industries, Ltd.) and the like are preferable. By dispersing the colorant in these binders at a high concentration, it is possible to impart adhesion to the lower layer and the like, which also contributes to the coated surface shape during spin coating and slit coating.

<Curing agent>
The curing agent is preferably added when an epoxy resin is used as the thermosetting compound. There are many types of curing agents for epoxy resins, and their properties, pot life with resin and curing agent mixture, viscosity, curing temperature, curing time, heat generation, etc. vary greatly depending on the type of curing agent used. An appropriate curing agent must be selected according to the purpose of use, use conditions, working conditions, and the like. The curing agent is described in detail in Chapter 5 of Hiroshi Kakiuchi “Epoxy resin (Shojodo)”. Examples of the curing agent are as follows.

  Those that act catalytically include tertiary amines, boron trifluoride-amine complexes, those that react stoichiometrically with functional groups of epoxy resins, polyamines, acid anhydrides, etc .; Examples include diethylenetriamine, polyamide resin, and medium temperature curing examples such as diethylaminopropylamine and tris (dimethylaminomethyl) phenol; examples of high temperature curing include phthalic anhydride and metaphenylenediamine. In terms of chemical structure, in the case of amines, diethylenetriamine as an aliphatic polyamine; metaphenylenediamine as an aromatic polyamine; tris (dimethylaminomethyl) phenol as a tertiary amine; phthalic anhydride as an acid anhydride; polyamide resin Polysulfide resin, boron trifluoride-monoethylamine complex; Synthetic resin initial condensate includes phenol resin, dicyandiamide and the like.

  These curing agents react with an epoxy group by heating and polymerize to increase the crosslinking density and cure. For thinning, both the binder and the curing agent are preferably as small as possible. In particular, the curing agent is 35% by mass or less, preferably 30% by mass or less, more preferably 25% by mass or less with respect to the thermosetting compound. It is preferable that

<Curing catalyst>
In order to realize a high colorant concentration, curing by reaction between epoxy groups is effective in addition to curing by reaction with the aforementioned curing agent. For this reason, a curing catalyst can be used without using a curing agent. The addition amount of the curing catalyst is about 1/10 to 1/1000, preferably about 1/20 to 1/500, more preferably 1/100 to 1/1000 on the mass basis with respect to an epoxy resin having an epoxy equivalent of about 150 to 200. It can be cured with a slight amount of about 30 to 1/250.

<Solvent>
The thermosetting composition can be used as a solution dissolved in various solvents. Each solvent used in the thermosetting composition is basically not particularly limited as long as the solubility of each component and the applicability of the thermosetting composition are satisfied.

<Dispersant>
A dispersant can be added to improve the dispersibility of the pigment. As the dispersant, known ones can be appropriately selected and used, and examples thereof include a cationic surfactant, a fluorosurfactant, and a polymer dispersant.

  As these dispersants, many types of compounds are used. For example, phthalocyanine derivatives (commercially available products EFKA-745 (manufactured by Efka)), Solsperse 5000 (manufactured by Nippon Lubrizol); organosiloxane polymer KP341 (Shin-Etsu) Chemical Industries, Ltd.), (meth) acrylic acid (co) polymer polyflow No. 75, no. 90, no. Cationic surfactants such as 95 (manufactured by Kyoeisha Yushi Chemical Co., Ltd.) and W001 (manufactured by Yusho Co., Ltd.); polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene Nonionic surfactants such as octyl phenyl ether, polyoxyethylene nonyl phenyl ether, polyethylene glycol dilaurate, polyethylene glycol distearate, sorbitan fatty acid ester; anionic interfaces such as W004, W005, W017 (manufactured by Yusho Co., Ltd.) Activator: EFKA-46, EFKA-47, EFKA-47EA, EFKA polymer 100, EFKA polymer 400, EFKA polymer 401, EFKA polymer 450 (manufactured by Morishita Sangyo Co., Ltd.), Disperseide , Disperse Aid 8, Disperse Aid 15, Disperse Aid 9100 (manufactured by San Nopco), etc .; Solsperse 3000, 5000, 9000, 12000, 13240, 13940, 17000, 24000, 26000, 28000, etc. Various Solsperse dispersants (manufactured by Nippon Lubrizol); Adeka Pluronic L31, F38, L42, L44, L61, L64, F68, L72, P95, F77, P84, F87, P94, L101, P103, F108, L121, P -123 (Asahi Denka Co., Ltd.) and Isonet S-20 (Sanyo Kasei Co., Ltd.).

  A dispersing agent may be used independently and may be used in combination of 2 or more type. Usually, the amount of the dispersant added to the colored thermosetting composition is preferably about 0.1 to 50 parts by mass with respect to 100 parts by mass of the pigment.

<Other additives>
Various additives can be further added to the colored thermosetting composition of the present invention as necessary. Specific examples of the various additives include, for example, various additives described in JP-A-2005-326453.

  Next, an example of the solid-state image sensor forming process 50 for forming the solid-state image sensor 10 will be described with reference to FIG. The solid-state imaging device forming step 50 is roughly divided into a device protective layer forming step 51, a color filter forming step 52, a planarizing film forming step 53, and a microlens forming step. Prior to the color filter forming step 52, a step of forming the light shielding film 34, the insulating film 35, etc. on the semiconductor substrate 25 on which the light receiving element 21 etc. are formed is performed. Is omitted.

  As shown in FIG. 5, in the device protective layer forming step 51, a device protective layer 36 made of silicon nitride is formed on the insulating film 35 using a CVD method or the like at a high temperature. The thickness of the device protective layer 36 is formed to be thicker than the thickness of the color filter 22 as described above, and is, for example, 0.7 μm.

  Returning to FIG. 4, in the color filter forming step 52, after forming the recess 37 in the device protection layer 36, the color filter 22 (the respective color pixels 40 </ b> R, 40 </ b> G, 40 </ b> B and the separation wall 41) is formed in the recess 37.

  The color filter forming step 52 is roughly divided into a concave portion forming step 58, a porous silica layer forming step 59, a green opening forming step 60, a green (solid) layer forming step 61, and a blue opening forming step. 62, a blue (solid) layer forming step 63, a red opening forming step 64, a red (solid) layer forming step 65, and a CMP step 66. Hereinafter, each step will be described in detail with reference to FIGS. 4 and 6 to 24. In addition, in order to prevent complication of the drawings, here, a case where the respective color pixels 40R, 40G, and 40B are formed in a line (see FIG. 24) will be described as an example.

  In the recess forming step 58, the device protective layer 36 is dry-etched (anisotropic etching) to form the recess 37 and the polishing stopper portion 38. The recess forming process 58 is roughly composed of a photoresist layer forming process 68, an exposure / development / baking process 69, and a dry etching process 70.

  In FIG. 6, in the photoresist layer forming step 68, a photoresist is applied on the device protection layer 36 using a known spin coater, and then subjected to a heat treatment by a known heating apparatus such as a hot plate or an oven, and the photoresist is formed. Layer 72 is formed. As the positive type photoresist, a positive type photosensitive resin composition sensitive to ultraviolet rays (g rays, i rays), far ultraviolet rays including excimer lasers such as KrF and ArF, and electron beams can be used. .

  In the exposure / PEB (Post Exposure Bake) / development / bake process 69, first, a well-known exposure apparatus (i-line stepper) is used to irradiate the photoresist layer 72 with an exposure beam, and this photo The resist layer 72 is exposed. For example, when a positive type photoresist is used, the exposure light beam is irradiated on the formation region of the recess 37 (hereinafter referred to as the recess formation region) in the photoresist layer 72. Next, after performing PEB processing, the exposed photoresist layer 72 is developed with a known developer.

  As shown in FIG. 7, the exposed portion of the photoresist layer 72 (unexposed portion when a negative photoresist is used) is removed by development processing, and a resist pattern 72 a is formed on the device protection layer 36. The In addition, as a developing solution, the combination of various organic solvents and alkaline aqueous solution can be used. The resist pattern 72a exposes the recessed portion forming region of the device protective layer 36 and covers other regions. After the development processing is completed, the resist pattern 72a is post-baked using the above-described heating device or the like. Thus, the exposure / development / baking step 69 is completed.

  In the dry etching step 70, first, a known dry etching apparatus is used, and the device protection layer 36 is dry etched using the resist pattern 72 a as a mask. The dry etching process is preferably performed in such a form that the recess forming region of the device protective layer 36 is removed by a dry etching process using a mixed gas containing a gas selected from fluorine, chlorine and bromine and an oxygen gas.

<Dry etching>
The mixed gas used in dry etching has a composition containing at least one fluorine-based gas and oxygen gas from the viewpoint that the colored layer portion (the portion to be etched) removed by the dry etching method can be processed into a rectangular shape. Most preferred.

A known fluorine-based gas can be used as the fluorine-based gas, but a fluorine-based compound gas represented by the following formula (1) is preferable.
C _n H _m F _l Formula (1)
In said formula (1), n represents 1-6, m represents 0-13, and l represents 1-14.

Examples of the fluorine-based gas represented by the above formula (1) include CF ₄ , C ₂ F ₆ , C ₃ F ₈ , C ₂ F ₄ , C ₄ F ₈ , C ₄ F ₆ , C ₅ F ₈ , And at least one selected from the group of CHF ₃ . As the fluorine-based gas in the present invention, one kind of gas can be selected from the above group, and two or more kinds of gases can be used in combination. Furthermore, among these, from the viewpoint of maintaining the rectangularity of the etched portion, the fluorine-based gas may be at least one selected from the group consisting of CF ₄ , C ₂ F ₆ , C ₄ F ₈ , and CHF _3. CF ₄ or C ₄ F ₆ is preferable, and a mixed gas of CF ₄ and C ₄ F ₆ is most preferable.

In addition, the mixed gas used in dry etching may contain other gases in addition to the above-described fluorine-based gas and oxygen gas from the viewpoint of maintaining the partial pressure control stability of the etching plasma and maintaining the perpendicularity of the shape to be etched. preferable. Other gases include helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and other rare gases, and halogens including halogen atoms such as chlorine, fluorine, and bromine atoms. It is preferable to include at least one selected from the group of system gases (for example, CCl ₄ , CClF ₃ , AlF ₃ , AlCl _3, etc.), N ₂ , CO, and CO ₂ , and Ar, He, Kr, N ₂ , And at least one selected from the group of Xe, more preferably at least one selected from the group of He, Ar, and Xe.

  In addition, when it is possible to maintain the partial pressure control stability of the etching plasma and the perpendicularity of the shape to be etched, the mixed gas used in the dry etching is composed of only a fluorine-based gas and an oxygen gas. Also good.

Moreover, when performing dry etching, it is preferable to obtain | require the etching process time in advance with the following method.
(1) The etching rate [nm / min] of the device protective layer 36 is calculated.
(2) The processing time required to etch a desired thickness by dry etching is calculated from the etching rate calculated in (1) above.

  As shown in FIG. 8, a recess 37 and a polishing stopper portion 38 are formed in the device protection layer 36 by performing the dry etching process described above. Since the depth of the concave portion 37 is equal to the thickness of the color filter 22, the thickness of the color filter 22 can be adjusted by adjusting the depth (etching amount) of the concave portion 37. The polishing stopper portion 38 is used for confirming the CMP end point during the CMP step 66.

  After the dry etching process using a fluorine-based gas or the like is completed, the resist pattern 72a (photoresist) is removed by oxygen ashing using oxygen plasma. This oxygen ashing is performed using a known oxygen ashing apparatus. The oxygen ashing conditions are, for example, oxygen flow rate: 100 ml, pressure: 5 Pa, and other conditions can be set as appropriate. When the device protective layer 36 is an inorganic film, WET cleaning may be performed. Thus, the dry etching process 70 is completed.

  As shown in FIG. 9, in the porous silica layer forming step 59, a porous silica layer 74 that is a low refractive index layer (material layer) is formed so as to fill the concave portion 37 while covering the device protective layer 36. . At this time, the thickness of the porous silica layer 74 on the concave portion 37 is formed to be larger than the depth of the concave portion 37.

  The porous silica layer 74 is obtained by applying the film forming composition described in JP-A-2008-231174 to the chip substrate 12a (device protective layer) by any coating method such as spin coating, roller coating, dip coating, or scanning. 36) After coating on, the solvent in the coating layer is removed by heat treatment to cure the coating layer. As a coating method, a spin coating method and a scanning method are preferable, and a spin coating method is particularly preferable.

  The above-mentioned heat treatment method of the coating layer is not particularly limited, but generally used hot plate heating, heating method using a furnace, light irradiation heating using a xenon lamp by RTP (Rapid Thermal Processor), etc. Can be applied. A heating method using hot plate heating or furnace is preferable. Commercially available equipment can be used as the hot plate, and the Clean Track Series (manufactured by Tokyo Electron), D-Spin Series (manufactured by Dainippon Screen Mfg. Co., Ltd.), SS Series or CS Series (Tokyo Ohka Kogyo ( It is preferable to use the product etc. As the furnace, α series (manufactured by Tokyo Electron Ltd.) or the like is preferably used.

  The film-forming composition (coating layer) described above is cured by heating, for example, when a carbon triple bond undergoes a polymerization reaction. The temperature during the heat treatment is preferably 100 to 450 ° C, more preferably 200 to 420 ° C, and particularly preferably 350 to 400 ° C. The heat treatment conditions are preferably in the range of 1 minute to 2 hours, more preferably 10 minutes to 1.5 hours, and particularly preferably 30 minutes to 1 hour. The heat treatment may be performed in several times. Further, this heating is particularly preferably performed in a nitrogen atmosphere in order to prevent thermal oxidation by oxygen. Instead of performing the heat treatment, the coating layer may be cured by irradiating the coating layer with a high energy ray to cause the above-described polymerization reaction of the carbon triple bond. Examples of high energy rays include electron beams, ultraviolet rays, and X-rays, but are not particularly limited to any of these.

The energy when an electron beam is used as the high energy beam is preferably 0 to 50 keV, more preferably 0 to 30 keV, and particularly preferably 0 to 20 keV. The total dose of the electron beam is preferably 0 to 5 μC / cm ² , more preferably 0 to ² μC / cm ² , and particularly preferably 0 to 1 μC / cm ² . 0-450 degreeC is preferable, as for the substrate temperature at the time of irradiating an electron beam, 0-400 degreeC is more preferable, and 0-350 degreeC is especially preferable. Further, the inside of the chamber in which the chip substrate 12a is set is pressurized during electron beam irradiation. This pressure is preferably 0 to 133 kPa, more preferably 0 to 60 kPa, and particularly preferably 0 to 20 kPa.

  From the viewpoint of preventing oxidation of the polymer, the atmosphere around the substrate is preferably an inert atmosphere such as Ar, He, or nitrogen. Further, a gas such as oxygen, hydrocarbon, or ammonia may be added for the purpose of reaction with plasma, electromagnetic waves, or chemical species generated by interaction with an electron beam. Furthermore, the electron beam irradiation may be performed a plurality of times. In this case, the electron beam irradiation conditions need not be the same each time, and may be performed under different conditions each time.

Moreover, you may use an ultraviolet-ray as a high energy ray. The irradiation wavelength region when using ultraviolet rays is preferably 190 to 400 nm, and the output is preferably 0.1 to 2,000 mWcm ² immediately above the substrate. The substrate temperature at the time of ultraviolet irradiation is preferably 250 to 450 ° C, more preferably 250 to 400 ° C, and particularly preferably 250 to 350 ° C. As in the case of using the electron beam described above, the atmosphere around the substrate is preferably an inert atmosphere such as Ar, He, or nitrogen from the viewpoint of preventing oxidation of the polymer. The pressure is preferably 0 to 133 kPa.

  Returning to FIG. 4, in the green opening forming step 60, the porous silica layer 74 on the recess 37 is etched to open the green opening 76G (see FIG. 25) where the green pixel 40G formation region (see FIG. 25) is opened. 12). As a method for etching the porous silica layer 74, dry etching is preferable. Dry etching can be performed using ammonia plasma, fluorocarbon plasma, or the like as appropriate. These plasmas can use not only Ar but also oxygen, or gases such as nitrogen, hydrogen, and helium. In addition, after etching, the photoresist (resist pattern) used as an etching mask is preferably dissolved and removed with an organic solvent. However, if no damage (film reduction or the like) occurs due to the ashing process, the ashing process may be performed. In addition, a cleaning process may be performed.

  The green opening forming step 60 includes a photoresist layer forming step 77, an exposure / development / baking step 78, and a dry etching / peeling step 79.

  As shown in FIG. 10, in the photoresist layer forming step 77, as in the above-described photoresist layer forming step 68, a photoresist (either positive type or negative type) is formed on the porous silica layer 74 using a spin coater or the like. Is applied, and then a heat treatment is performed by a heating device to form a photoresist layer 81.

  In the exposure / PEB / development / bake process 78, as in the above-described exposure / development / bake process 69, the photoresist layer 81 is first irradiated with exposure light, and this photoresist layer 81 is exposed. For example, when a positive photoresist is used, the exposure light beam is irradiated onto the formation area (see FIG. 25) of the green pixel 40G in the photoresist layer 81. Next, after performing the PEB process, the exposed photoresist layer 81 is developed with a well-known developer to perform a post-bake process.

  As shown in FIG. 11, the exposed portion of the photoresist layer 81 (positive type) is removed by development processing, and a resist pattern 81 a is formed on the porous silica layer 74. The resist pattern 81a exposes the green pixel formation region of the porous silica layer 74 and covers other regions (locations serving as the separation wall 41 and blue / red pixel formation regions). Then, after the development processing is completed, the exposure / development / baking step 78 is completed by post-baking the resist pattern 81a with the above-described heating device or the like.

  In the dry etching / peeling step 79, the porous silica layer 74 is first dry etched using a known dry etching apparatus with the resist pattern 81a as a mask. This dry etching is performed in two stages, ie, a first stage etching and a second stage etching. In the first stage etching, a mixed gas of fluorine-based gas and oxygen gas is used, and the porous silica layer 74 is etched to a region (depth) where the device protective layer 36 is not exposed.

  In the second-stage etching, after the first-stage etching, a mixed gas of nitrogen gas and oxygen gas is used, and etching is performed up to a region (depth) where the device protection layer 36 is exposed. In the second stage etching, the amount of etching can be suppressed by using a mixed gas of nitrogen gas and oxygen gas. As a result, the etching amount can be accurately controlled. Furthermore, etching damage to the chip substrate 12a (device protective layer 36) due to the fluorine-based gas can be avoided.

<First stage etching>
The calculation method of the mixed gas (fluorine-based gas, oxygen gas) and etching time used in the first stage etching is basically the same as the etching in the dry etching process 70 described above, and thus the description thereof is omitted. However, as the fluorine-based gas, CF ₄ and / or C ₂ F ₆ are preferable, and CF ₄ is particularly preferable.

  In the first-stage etching, it is preferable that the content ratio of fluorine-based gas and oxygen gas (fluorine-based gas / oxygen gas) is 2/1 to 8/1 in terms of flow rate. By making it within this range, adhesion of the etching product to the side wall of the resist pattern 81a during the etching process can be prevented, and further, the resist pattern 81a can be suppressed by suppressing the generation of the side wall protective film during the resist pattern peeling described later. Is easy to peel off. In particular, the content ratio of the fluorine-based gas and the oxygen gas is 2/1 to 6/1 in order to prevent the redeposition of the etching product to the photoresist layer side wall while maintaining the rectangular shape of the etched portion. Is preferable, and 3/1 to 5/1 is particularly preferable.

  The mixed gas used in the first etching step may contain other gas in addition to the fluorine-based gas and oxygen gas when the oxygen gas is set to 1 in terms of the rectangularity of the etching pattern. The flow rate ratio is preferably 25 or less, more preferably 10 or more and 20 or less, and particularly preferably 14 or more and 18 or less.

<Second stage etching>
The mixed gas used in the second stage etching includes nitrogen gas and oxygen gas, but may contain a fluorine-based gas as long as the effects of the present invention are not impaired. The content ratio of the fluorine-based gas to the oxygen gas (fluorine-based gas / oxygen gas) is preferably 5% or less by flow rate ratio, and particularly preferably does not contain the fluorine-based gas. When the content of the fluorine-based gas is within the above range, damage to the chip substrate 12a (device protective layer 36) can be more effectively suppressed.

  The content ratio of nitrogen gas to oxygen gas (nitrogen gas / oxygen gas) in the mixed gas is preferably 10/1 to 3/1 in terms of flow rate. By setting it within this range, adhesion of the etching product to the side wall of the resist pattern 81a can be more effectively suppressed, and further, the resist pattern 81a can be more easily peeled off. In particular, from the viewpoint of maintaining the rectangularity of the part to be etched and preventing the reattachment of the etching product, the flow ratio is preferably in the range of 20/1 to 3/1, more preferably 15/1 to 4/1. 10/1 to 5/1 is particularly preferable.

  In addition to the nitrogen gas and the oxygen gas, in addition to the nitrogen gas and the oxygen gas, the above-mentioned mixed gas may further contain helium (He), It preferably includes at least one gas selected from the group of neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe), and at least one selected from the group of He, Ar, and Xe More preferably, it contains seed gas. However, when it is possible to maintain the partial pressure control stability of the etching plasma and the perpendicularity of the shape to be etched, the mixed gas is composed only of nitrogen gas and oxygen gas.

  The content of other gases that the above-mentioned mixed gas may further contain in addition to nitrogen gas and oxygen gas is preferably 25 or less in terms of a flow rate ratio when oxygen gas is 1, and is 5 or more and 20 or less. It is preferable that it is 8 or more and 12 or less.

  In the second stage etching, for example, the dry etching process is terminated after the processing time calculated in the same manner as in the first stage etching. Further, the dry etching processing time may be managed by detecting the end point. Specifically, the end point is the time when a plasma gas that emits light when the device protective layer 36 is etched with the plasma gas is detected by a known plasma emission monitor. The management of the dry etching processing time is preferably performed in the latter (end point detection). The etching processing time is preferably within 10 minutes, and more preferably within 7 minutes.

  The second stage etching preferably further includes an over-etching process. After removing the green pixel formation region of the porous silica layer 74 by the second stage etching, the etching residue remaining while maintaining the rectangularity of the pattern can be efficiently removed by further over-etching, In addition, the occurrence of damage to the chip substrate 12a (device protection layer 36) can be more effectively suppressed.

  The overetching treatment is preferably performed by setting an overetching time. Although the over-etching time can be arbitrarily set, the etching processing time (t1) in the first-stage etching and the etching processing time in the second-stage etching in terms of maintaining the etching resistance of the photoresist and the rectangularity of the pattern to be etched. It is preferably 30% or less of the total processing time (t1 + t2) with (t2), more preferably 5 to 25%, and particularly preferably 15 to 20%.

  As shown in FIG. 12, the portion of the porous silica layer 74 not covered with the resist pattern 81a is removed by dry etching. As a result, a green opening 76 </ b> G is formed in the porous silica layer 74 on the recess 37. Next, a peeling process of the resist pattern 81a (photoresist) is performed. This stripping treatment is performed using an organic solvent or a photoresist stripping solution. In the second stage etching, a mixed gas containing nitrogen gas and oxygen gas is used, so that the resist pattern 81a can be more easily peeled off with an organic solvent or a stripping solution. In addition, the peeling process of the resist pattern 72a in the dry etching process 70 of the above-described device protective layer 36 may be performed by the same method.

  As shown in FIG. 13, the resist pattern 81a on the porous silica layer 74 is removed by the peeling process. Note that a solvent removal treatment (cleaning treatment) and a dehydration treatment (baking treatment) may be performed after the peeling treatment.

  As shown in FIG. 14, the line width of the green opening 76G (the width in the direction orthogonal to the film thickness direction of the porous silica layer 74) is larger than the pitch P of the color pixels 40R, 40G, 40B of the color filter 22. It is preferable to form it small. Separation walls having a line width of (P−W) × 2 between the color pixels 40R, 40G, and 40B by forming the color openings 76R, 76G, and 76B (see FIGS. 4 and 24) with the same size. 41 can be formed. The line width of the separation wall 41 is preferably 0.05 μm or more and 0.20 μm or less.

  As shown in FIG. 15, in the green layer forming step 61, the aforementioned green thermosetting composition is applied onto the porous silica layer 74 using a spin coater or the like so as to fill the green opening 76G. Next, the coating layer (film) is post-baked using a heating device or the like. As a result, a green layer 83G is formed on the porous silica layer 74.

  The blue opening forming step 62 (see FIG. 4) includes a photoresist layer forming step, an exposure / PEB / development / baking step, a dry etching / peeling step, as in the green opening forming step 60 described above. Are sequentially performed to form a blue opening portion 76B (see FIG. 18) in the porous silica layer 74 having an opening in the formation region (see FIG. 25) of the blue pixel 40B.

  As shown in FIG. 16, in the photoresist layer forming step, a photoresist layer 84 is formed on the green layer 83G in the same manner as the photoresist layer forming step 77 described above. Then, as shown in FIG. 17, in the exposure / PEB / development / bake process, the photoresist layer 84 is exposed / PEB / development / bake process in the same way as the exposure / PEB / development / bake process 78 described above, and the porous layer is porous. A blue pixel formation region of the porous silica layer 74 is exposed, and a resist pattern 84a is formed to cover the region other than this region (the portion to be the separation wall 41 and the green / red pixel formation region).

  Next, as shown in FIG. 18, in the dry etching / peeling step, the green layer 83G and the porous silica layer 74 are dry-etched using the resist pattern 84a as a mask in the same manner as the dry etching / peeling step 79 described above. The pattern 84a is peeled off. As a result, a blue opening 76 </ b> B is formed in the green layer 83 </ b> G and the porous silica layer 74 on the recess 37. The blue opening 76B is formed in the same size as the above-described green opening 76G so that a portion that becomes the separation wall 41 remains (see FIG. 14).

  As shown in FIG. 19, in the blue layer forming step 63, the blue layer is formed on the porous silica layer 74 (green layer 83G) so as to fill the blue opening 76B in the same manner as the green layer forming step 61 described above. 83B is formed.

  In the red opening forming step 64 (see FIG. 4), the photoresist layer forming step, the exposure / PEB / development / baking step, and the dry etching / peeling step are performed in the same manner as each of the opening forming steps 60 and 62 described above. Are sequentially executed to form red openings 76R (see FIG. 22) in the formation regions of red pixels 40R (see FIG. 25) in the green / blue layers 83G and 83B and the porous silica layer 74.

  As shown in FIG. 20, in the photoresist layer forming step, a photoresist layer 85 is formed on the green layer 83G. Then, as shown in FIG. 21, in the exposure / PEB / development / bake process, the photoresist layer 85 is exposed / PEB / development / bake to expose the red pixel formation region of the porous silica layer 74. A resist pattern 85a is formed to cover areas other than the areas (locations that become the separation walls 41 and green / blue pixel formation areas).

  Next, as shown in FIG. 22, in the dry etching / peeling step, the green / blue layers 83G and 83B and the porous silica layer 74 are dry etched using the resist pattern 85a as a mask, and then the resist pattern 85a is peeled off. As a result, a red opening 76 </ b> R is formed in the green / blue layer 83 </ b> G and the porous silica layer 74 on the recess 37. The red opening 76R is formed in the same size as each of the openings 76G and 76B described above so that a portion that becomes the separation wall 41 remains (see FIG. 14).

  As shown in FIG. 23, in the red layer forming step 65, the porous silica layer 74 (blue layer 83 </ b> B) is formed so as to fill the red opening 76 </ b> R in the same manner as each of the color layer forming steps 61 and 63 described above. A red layer 83R is formed. In this manner, the openings 76G, 76B, and 76R corresponding to the color pixels 40G, 40B, and 40R are sequentially formed in the porous silica layer 74 by repeating the opening forming process and the colored layer forming process three times alternately. In addition, the color layers 83G, 83B, and 83R are sequentially laminated on the porous silica layer 74 so as to fill the openings whenever the openings 76G, 76B, and 76R are formed.

  In the CMP process 66 (see FIG. 4), a polishing process (planarization process) is performed on the entire exposed surface of the chip substrate 12a using a CMP apparatus. Specifically, the red layer 83R, until the surface of the polishing stopper portion 38 of the device protective layer 36 is exposed (the porous silica layer 74 and the color layers 83G, 83B, 83R on the polishing stopper portion 38 are removed). Polishing is sequentially performed on the surfaces of the blue layer 83 </ b> B, the green layer 83 </ b> G, and the porous silica layer 74.

[Polishing]
As is well known, the CMP apparatus supplies each of the color layers 83R, 83B, 83G and the porous silica layer by supplying slurry between both surfaces while bringing the surface of each layer into contact with the polishing surface of the turntable with a rotating polishing pad. 74 is polished. As polishing conditions, a slurry in which silica fine particles are dispersed is used as an abrasive, slurry flow rate: 100 to 250 ml / min, wafer pressure: 0.2 to 5.0 psi, retainer ring pressure: 1.0 to 2.5 psi. Use abrasive cloth made of urethane foam. The polishing time is the time until the polishing stopper portion 38 is exposed, and the overpolishing rate is set to 20%, for example, to complete the polishing process. Note that overpolishing may be performed after the polishing stopper portion 38 is exposed.

  As shown in FIG. 24, when the surface of the polishing stopper portion 38 is exposed by the polishing process, the thickness of each of the color layers 83R, 83B, 83G and the porous silica layer 74 is uniform, that is, equal to the depth of the concave portion 37. The color filter 22 including the red / blue / green pixels 40R, 40B, and 40G and the separation wall 41 is formed. Thus, in this embodiment, the film thickness of the color filter 22 can be easily adjusted by adjusting the depth of the recess 37. Thus, all the steps of the color filter forming step 52 are completed.

  As shown in FIG. 25, when the color filter forming step 52 is completed, the color pixels 40R, 40B, and 40G are two-dimensionally arranged on the concave portion 37, and a separation wall 41 is provided at the boundary between the color pixels 40R, 40B, and 40G. It is done. As described above, in FIGS. 5 to 24, the case where the color pixels 40R, 40G, and 40B are formed in a line is described in order to prevent the drawings from becoming complicated. It is formed with the arrangement pattern shown.

  Returning to FIG. 4, in the planarization film forming step 53, the planarization film 42 is formed so as to cover the surfaces of the color filter 22 and the device protection layer 36. In the microlens formation step 54, the microlenses 23 are formed on the planarizing film 42 and above the light receiving element 21. With the above, all steps of the solid-state image sensor forming step 50 are completed, and the solid-state image sensor 10 is formed.

  As described above, according to the present invention, when the color filter 22 including the color pixels 40R, 40B, and 40G and the separation wall 41 is manufactured, the color filter 22 is formed in the concave portion 37 of the device protection layer 36, whereby the device The polishing stopper portion 38 of the protective layer 36 can be used for end point detection in the CMP process 66. As a result, it is not necessary to separately form a polishing stopper layer, so that an increase in the types of materials necessary for forming the color filter 22 is prevented.

  In addition, the number of executions of the CMP step 66 can be reduced to one by performing the CMP step 66 after alternately repeating the opening formation step for each color and each color layer forming step three times.

  Further, by forming the separation wall 41 at the boundary between the color pixels 40R, 40B, and 40G, the occurrence of color mixing can be suppressed. Furthermore, each color pixel 40R, 40B, 40G is formed of a colored thermosetting composition that does not contain a photosensitive component, so that the photosensitive component has a film thickness of the color filter as when each color pixel is formed of a photosensitive composition. There is no risk of affecting it. As a result, each of the color pixels 40R, 40B, and 40G can be thinned, so that deterioration of color shading and occurrence of color mixing can be suppressed.

  As described above, according to the present invention, the color filter 22 that suppresses color mixing, has excellent color reproducibility, and suppresses color shading can be manufactured at a lower cost than the prior art. In addition, the cost of manufacturing the solid-state imaging device 10 can be reduced by reducing the cost of the car filter 22.

  In the above embodiment, the device protective layer 36 is dry-etched to form the recesses 37 and the like. However, the present invention is not limited to this, and if the depth of the recesses 37 can be controlled, for example, Alternatively, wet etching using buffered hydrofluoric acid may be performed.

  In the above embodiment, the case where the CMP process is executed after the formation of the color layers 83R, 83G, and 83B to perform the flattening process (polishing process) on the entire exposed surface of the chip substrate 12a has been described. It is not limited to this. For example, as a planarization process, an etch back process may be performed using a dry etching apparatus.

  In the above embodiment, the case where the green layer 83G, the blue layer 83B, and the red layer 83R are formed in the order has been described as an example. However, the present invention is not limited to this, and the order is appropriately changed. May be. The present invention can also be applied when the color filter is composed of four or more colored pixels.

  In the above embodiment, the case where the separation wall 41 is formed of a low refractive index material such as porous silica has been described. However, the present invention is not limited to this, and a non-permeable coloring material is used as the separation wall. A so-called black matrix may be formed. Also in this case, the occurrence of color mixing is suppressed.

  In the above embodiment, the method for producing a color filter used in a solid-state imaging device has been described. However, the present invention is not limited to this, and the present invention is also applied to the production of a color filter used in a liquid crystal display or the like. Can be applied.

  Examples for obtaining the color filter according to the present invention will be specifically described below. In this embodiment, the porous silica used for forming the separation wall 41 and the red / green / blue thermosetting composition used for forming the red, green, and blue pixels 40R, 40G, and 40B are as follows. Prepared.

[Preparation of porous silica]
Porous silica (coating solution) was prepared according to the method described in JP-A-2008-231174.

[Preparation of blue thermosetting composition]
Before preparing the blue thermosetting composition, the following blue pigment dispersion was first prepared.
-"Pigment Blue 15: 6" 125 parts by mass-"Pigment Violet" 25 parts by mass-Dispersant PLADDED211 (manufactured by Enomoto Kasei Co., Ltd.) 40 parts by mass-Benzyl methacrylate / glycidyl methacrylate copolymer 15 parts by mass -PGMEA 755 parts by mass Each of the above materials was agitated with a homogenizer, and then finely dispersed with a disperser (Dispermat, manufactured by GETZMANN) using 0.3 mm zirconia beads for 5 hours to give a blue pigment. A dispersion was prepared.

Next, a non-photosensitive coloring composition, that is, a blue thermosetting composition was prepared by further adding the following thermosetting resin to the blue pigment dispersion.
EHPE-3150 0.5 parts by mass (based on the blue pigment dispersion)
Furthermore, PGMEA was added to the blue pigment dispersion and the thermosetting resin, and the solid content of the composition was diluted to 13.0%.

[Preparation of red thermosetting composition]
First, the following red pigment dispersion was prepared.
-"Pigment Red 254" 80 parts by mass-"Pigment Yellow 139" 20 parts by mass-Dispersant EDAPLAN472 (manufactured by Enomoto Kasei Co., Ltd.) 30 parts by mass-Benzyl methacrylate / glycidyl methacrylate copolymer 10 parts by mass PGMEA 700 parts by mass or less, and the same treatment as that for preparing the blue pigment dispersion was performed to prepare a red pigment dispersion.

Next, a non-photosensitive coloring composition, that is, a red thermosetting composition was prepared by further adding a thermosetting resin to the red pigment dispersion.
EHPE-3150 0.8 part by mass (based on the above red pigment dispersion)
Furthermore, PGMEA was added to the red pigment dispersion and the thermosetting resin, and the solid content of the composition was diluted to 15.0%.

[Preparation of green thermosetting composition]
First, the following green pigment dispersion was prepared.
-"Pigment Green 36" 90 parts by mass-"Pigment Green 7" 25 parts by mass-"Pigment Yellow 139" 40 parts by mass-Dispersant PALDDED 151 (manufactured by Enomoto Kasei Co., Ltd.) 20 parts by mass-Benzyl methacrylate / Glycidyl methacrylate copolymer 10 parts by mass / PGMEA 630 parts by mass or less The same treatment as in the preparation of the blue pigment dispersion was performed to prepare a green pigment dispersion.

Next, a non-photosensitive coloring composition, that is, a green thermosetting composition was prepared by further adding a thermosetting resin to the green pigment dispersion.
EHPE-3150 0.8 part by mass (based on the green pigment dispersion)
Furthermore, PGMEA was added to the green pigment dispersion and the thermosetting resin, and the solid content of the composition was diluted to 13.0%.

[Manufacture of color filters]
The color filter 22 was formed by the following procedure using the porous silica and the red / green / blue thermosetting composition. In this embodiment, the color filter 22 is manufactured on the Si wafer substrate instead of the above-described chip substrate 12a.

[Device protection layer formation process]
A device protection layer 36 made of silicon nitride and having a thickness of 0.7 μm was formed on the Si wafer substrate by CVD. Thereafter, annealing was performed at 850 degrees for 60 minutes.

[Recess formation step]
<Photoresist layer formation process>
A photoresist (FHi622BC: manufactured by FUJIFILM Electronics Materials) was applied on the device protective layer 36, and then prebaked at 90 ° C. for 60 seconds to form a photoresist layer 72 having a thickness of 3.0 μm.

<Exposure / PEB / Development / Bake process>
Using an i-line stepper (manufactured by Nikon), the photoresist layer 72 is exposed at an exposure amount of 300 mJ / cm ² , further subjected to PEB treatment at 110 ° C. for 1 minute, and a developer (FHD-5: Fuji Film Electronics). The material was developed for 2 minutes, and then rinsed with pure water and dried by spin drying. Thereafter, a post-baking process was further performed at 110 ° C. for 1 minute to form a frame-shaped resist pattern 72a.

  Both the outer diameter of the resist pattern 72a and the shape of the opening were formed in a rectangular shape. The line width in the direction orthogonal to the film thickness direction of the resist pattern 72a was formed to 100 μm, and the major axis of the opening was set to 4000 μm.

<Dry etching process>
Using a dry etching apparatus (manufactured by Hitachi High-Technologies: U-621), the device protective layer 36 was dry-etched under the following etching conditions using the resist pattern 72a as a mask. The etching time was set to the depth of the recess 37 (0.5 μm in this embodiment) ÷ 0.1 (etching rate) = 5 (min).

<Etching conditions>
・ RF power: 800W
・ Antenna bias: 400W
・ Wafer bias: 200W
-Chamber internal pressure: 4.0 Pa
-Substrate temperature: 20 ° C
Mixed gas type and flow rate: Ar / CF ₄ / O ₂ = 800/200/50 ml
Si etching rate: 100 nm / min
-Photoresist etching rate: 300 nm / min
・ Over etching rate: 0%

  After the dry etching process was completed, the resist pattern 72a was removed by an oxygen ashing process. The conditions for the oxygen ashing treatment were set such that the oxygen flow rate was 100 ml and the pressure was 5 Pa. Thereafter, a cleaning process was performed on the Si wafer substrate. Specifically, using a photoresist stripping solution (MS-230C: manufactured by FUJIFILM Electronics Materials), cleaning is performed for 120 seconds, followed by pure water cleaning and spin drying to clean the Si wafer substrate. Went. Next, heat treatment (dehydration treatment) was performed at 100 ° C. for 2 minutes.

  A 1000 μm × 4000 μm recess 37 was formed in the device protective layer 36 by dry etching. The depth of the concave portion 37 was formed to be about 0.5 μm.

[Porous silica layer forming step]
The porous silica described above is applied on the device protection layer 36 so as to fill the concave portion 37, and then heated on a hot plate under a nitrogen stream at 250 ° C. for 60 seconds, and further in a nitrogen-substituted 400 ° C. oven for 60 seconds. The porous silica layer 74 having a film thickness of 0.55 μm (on the concave portion 37) was formed by baking for a minute.

[Green opening forming process]
<Photoresist layer formation process>
A photoresist layer 81 having a thickness of 0.8 μm was formed on the porous silica layer 74 in the same manner as the photoresist layer forming step of the above-described recess forming step.

<Exposure / PEB / Development / Bake process>
Basically, the photoresist layer 81 was exposed, PEB, developed, and baked under the same conditions as those in the photoresist layer forming step in the recess forming step described above to form a resist pattern 81a. However, the i-line stepper was changed to Canon, and the development processing time was changed to 1 minute. The opening width of the opening portion of the resist pattern 81a was 0.9 μm and the pitch was 1.0 μm.

<Dry etching process>
Using the resist pattern 81a as a mask, the porous silica layer 74 was dry etched (first stage etching, second stage etching, and overetching) under the following conditions.

<First stage etching conditions>
・ RF power: 800W
・ Antenna bias: 400W
・ Wafer bias: 200W
・ Internal pressure of chamber: 4.0 Pa
-Substrate temperature: 50 ° C
Mixed gas type and flow rate: Ar / CF ₄ / O ₂ = 800/200/40 ml
・ Etching time: 60 seconds

<Second-stage etching / over-etching conditions>
・ RF power: 600W
・ Antenna bias: 100W
・ Wafer bias: 250W
-Chamber internal pressure: 2.0 Pa
-Substrate temperature: 50 ° C
Mixed gas type and flow rate: N ₂ / O ₂ / Ar = 500/50/500 ml
・ Over etching rate: 20%

  The amount of scraping of the porous silica layer 74 in the first stage etching process was 500 nm, that is, the etching amount was about 91%, and the thickness of the remaining film of the porous silica layer 74 was about 50 nm. Further, the etching rate of the porous silica layer 74 in the second stage etching was 600 nm / min or more, and it took about 10 seconds to etch the remaining film of the porous silica layer 74. The etching time was calculated by adding 60 seconds of the first stage etching time and 10 seconds of the second stage etching time. As a result, the etching time was 60 + 10 = 70 seconds, the overetching time was 70 × 0.2 = 14 seconds, and the total etching time was set to 70 + 14 = 84 seconds.

  Dry etching was performed under the above conditions to form a green opening 76G in the porous silica layer 74. Next, using a photoresist stripping solution “MS230C” (manufactured by FUJIFILM Electronics Materials), stripping treatment for 120 seconds was performed to remove the resist pattern 81a. Since the opening width W of the green opening 76G is 0.96 μm and the pitch P is 1.0 μm, the line width of the separation wall 41 is assumed to be (P−W) × 2 = 0.08 μm.

[Green layer forming process]
A green thermosetting composition is applied on the porous silica layer 74 so as to fill the green opening 76G, and then subjected to a post-bake treatment at 200 ° C. for 5 minutes using a hot plate. 83G was formed. The thickness of the green layer 83G in the green opening 76G was formed to be 0.61 μm, and the thickness of the green layer 83G on the surface of the porous silica layer 74 (other than the concave portion 37) was formed to be 0.15 μm.

[Blue opening forming process]
In the same manner as the green opening forming step, a 1.2 μm-thick photoresist layer 84 is formed on the green layer 83G, and then the photoresist layer 84 is exposed, PEB, developed, and baked to form a resist pattern. 84a was formed. However, the exposure amount at the time of exposure was changed to 375 mJ / cm ² . In addition, the opening width and pitch of the openings of the resist pattern 84a are the same as those of the resist pattern 81a.

Next, the green layer 83G and the porous silica layer 74 were dry-etched using the resist pattern 84a as a mask under basically the same conditions as in the green opening forming step described above to form the blue opening 76B. However, “chamber internal pressure”, “mixed gas species and flow rate”, and “etching time” in the first stage etching were changed as follows.
・ Internal pressure of chamber: 3.0Pa
Mixed gas type and flow rate: Ar / CF ₄ / O ₂ = 800/200/50 ml
・ Etching time: 78 seconds

  The amount of scraping of the green layer 83G and the porous silica layer 74 in the first stage etching process was 463 nm, and the thickness of the remaining film of the porous silica layer 74 was about 398 nm. Further, the etching rates of the green layer 83G and the porous silica layer 74 in the second stage etching are 7000 nm / min or more and 600 nm / min or more, respectively, and about 34 for etching the remaining film of the porous silica layer 74. It took a second. The sum of 78 seconds of the first stage etching time and 34 seconds of the second stage etching time was calculated as the etching time. As a result, the etching time was 78 + 34 = 112 seconds, the overetching time was 112 × 0.2 = 22 seconds, and the total etching time was set to 112 + 22 = 134 seconds.

  Next, the resist pattern 84a was stripped under the same conditions as those for the resist pattern 81a. The opening width W of the blue opening 76B was 0.95 μm.

[Blue layer forming step]
Similarly to the formation of the green layer 83G, a blue layer 83B was formed on the green layer 83G (porous silica layer 74) so as to fill the blue opening 76B. The blue layer 83B in the blue opening 76B has a thickness of 0.60 μm.

[Red opening formation process]
In the same manner as the blue opening forming step, a photoresist layer 85 was formed on the blue layer 83B, and then the photoresist layer 85 was exposed, PEB, developed, and baked to form a resist pattern 85a. Next, under the same conditions as the blue opening forming step, the green / blue layers 83G and 83B and the porous silica layer 74 are dry-etched using the resist pattern 85a as a mask to form the red opening 76R, and then the resist pattern 85a was peeled off. However, the etching time for the first stage of the dry etching process was changed to 98 seconds, the etching time for the second stage was 34 seconds, the overetching time was 26 seconds, and the total etching time was 158 seconds. The opening width W of the red opening 76R was 0.95 μm.

[Red layer forming step]
Similarly to the formation of the green / blue layers 83G and 83B, the red layer 83R was formed on the blue layer 83B (the green layer 83G and the porous silica layer 74) so as to fill the red opening 76R. The red layer 83R in the red opening 76R has a thickness of 0.67 μm.

[CMP process]
Using a polishing (CMP) apparatus (BC-15 manufactured by AMT), the red / blue / green layer 83R until the polishing stopper portion 38 is exposed with a slurry semi-sparse 25 diluted solution (stock solution: pure water = 1: 19). 83B, 83G and the porous silica layer 74 were polished. At this time, the polishing treatment was performed under the conditions of slurry dilution liquid flow rate: 300 ml / min, wafer pressure: 1.2 psi, retainer ring pressure: 1.5 psi, polishing PAD rotation speed 50 rpm, and wafer rotation speed 30 rpm. The color filter 22 including the red, blue, and green pixels 40R, 40B, and 40G and the separation wall 41 was formed on the concave portion 37 by the polishing process.

  Further, the surface of the color filter 22 and the surface of the polishing stopper portion 38 (the surface other than the concave portion 37 of the device protective layer 36) were formed flat by polishing (CMP) treatment. The polishing time for flattening both was 120 sec (the film thickness of both was 0.5 μm). When the additional polishing was further performed for 30 seconds, the film thickness of the color filter 22 was about 0.47 μm. For this reason, it was determined that the amount of additional polishing was within the range of the over-polishing margin. After the polishing treatment, pure water cleaning and dehydration baking were performed, and the CMP process was completed.

  As a result of observing the cross section of the color filter 22 after performing the polishing process for 180 seconds in the CMP process, the pitch of the color pixels 40R, 40G, and 40B is about 1.0 μm, and the color pixels 40R, 40G, and 40B are separated from each other. The wall 41 had a uniform film thickness of about 0.47 μm, and the line width of the separation wall 41 was 0.08 μm to 0.09 μm, and the desired shape was obtained. As described above, in this example, it was confirmed that the color filter 22 of the present invention was formed without any problem.

DESCRIPTION OF SYMBOLS 10 Solid-state image sensor 10a Image pick-up part 22 Color filter 36 Device protection layer 37 Concave part 38 Polishing stopper part 40R, 40G, 40B Red pixel, green pixel, blue pixel 41 Separation wall 76R, 76G, 76B Red opening part, Green opening part , Opening for blue 83R, 83G, 83B Red layer, green layer, blue layer

Claims (8)

In a method for producing a color filter comprising a plurality of colored pixels arranged two-dimensionally on a protective layer that protects the surface of a substrate, and a separation wall provided at a boundary between different colored pixels,
A protective layer forming step of forming the protective layer on the substrate;
A recess forming step for forming a recess in the protective layer;
Forming a material layer of the separation wall on the protective layer so as to fill at least the recess;
Etching the material layer on the recess to form an opening so as to leave a portion to be the separation wall; and
A colored solid layer forming step of forming a colored solid layer on the material layer so as to fill the opening,
The opening forming step and the colored solid layer forming step are alternately repeated a plurality of times to sequentially form openings corresponding to the colored pixels of the plurality of colors in the material layer, and the openings are formed. Repeated steps of sequentially stacking a colored solid layer of a color corresponding to the opening on the material layer in order to fill the opening each time,
After the repeating step, each surface of the colored solid layer and the material layer is subjected to a flattening process until the peripheral edge of the concave portion of the protective layer is exposed, and the colored pixels of the plurality of colors and the surface of the concave layer A planarization process for forming a separation wall;
A method for producing a color filter, comprising:   The method for manufacturing a color filter according to claim 1, wherein the separation wall is formed of a material having a refractive index lower than that of the colored pixels of the plurality of colors.   The method for producing a color filter according to claim 1, wherein the separation wall is made of porous silica.   4. The color filter according to claim 1, wherein the separation wall has a line width in a direction orthogonal to a film thickness direction of the material layer of 0.05 μm to 0.20 μm. Method.   The color filter manufacturing method according to claim 1, wherein the flattening process is performed by a chemical mechanical polishing process.   6. The method of manufacturing a color filter according to claim 1, wherein the recess forming step is performed by a dry etching method.   The method for manufacturing a color filter according to claim 1, wherein the opening forming step is performed by a dry etching method.   A solid-state imaging device comprising a color filter manufactured by the method for manufacturing a color filter according to claim 1.

Images