JP2017117830A - Method of manufacturing colar filter for solid imaging element, colar filter for solid imaging element and solid imaging element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color filter for a solid imaging element having a comparative high opening ratio while suppressing mixed color due to enter of light from colored layers adjacent to each other.SOLUTION: A method of manufacturing a color filter for a solid imaging element includes a step in which, after coating colored resist of a first colored layer 3 on a partition layer 10 on which a reverse pattern of the first colored layer 3 is formed, by a photolithography method using a photo mask 4 for the first colored layer 3, a first color filter pattern composed of a plurality of first colored layers 3, at least one of an exposure amount and development time in the photolithography method is adjusted and the upper end of the first color filter pattern is made protrude on the reverse pattern of the first colored layer 3 formed in the partition layer 10.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method for manufacturing a color filter for a solid-state image sensor, a color filter for a solid-state image sensor, and a solid-state image sensor.

As a solid-state image pickup device that picks up a color image, for example, incident light is passed through green, red, and blue colorant layers of a color filter, and is color-divided into light of three colors, green, red, and blue, and is color-divided Some devices detect the intensity of light with a photoelectric conversion element and output an image signal. As a method for manufacturing a color filter, a photolithography method is often used.
Here, if there is no partition between the colored layers and a plurality of colored layers are simply arranged, light enters from the adjacent colored layers and color mixing occurs. As a method of preventing this color mixture, there is a method of forming a partition made of a material having a refractive index smaller than that of the colored layer between the colored layers (see Patent Documents 1 and 2).

Japanese Patent Laying-Open No. 2015-92521 JP 2009-75172 A

However, in the technique described in Patent Document 1, since a photomask that masks only the partition walls, that is, a dedicated photomask is used, the cost and the number of processes increase. In order to increase the aperture ratio, it is preferable that the partition wall width is small. However, in the technique described in Patent Document 1, it is difficult to form a narrow partition wall because the partition wall is easily collapsed. On the other hand, in the technique described in Patent Document 2, since a photomask that masks portions other than the colored layer is used, it is difficult to form a narrow partition wall with high dimensional accuracy due to the influence of positional accuracy.
The present invention pays attention to the above points, and a method for manufacturing a color filter for a solid-state image sensor capable of forming a partition wall layer having a narrow width and excellent dimensional accuracy while reducing the number of photomasks, and a color filter for a solid-state image sensor And it aims at providing a solid-state image sensor.

  In order to solve the above problems, according to one embodiment of the present invention, a first step of laminating a protective film and a partition layer in this order on a semiconductor substrate on which a photoelectric conversion element is formed, and a positive type on the partition layer A second step of forming a resist pattern having a reverse pattern of the first colored layer on the positive photoresist by photolithography using a photomask for the first colored layer after applying the photoresist; and a resist pattern A third step of performing dry etching on the partition layer using the mask as a mask to form a reverse pattern of the first colored layer on the partition layer, and a first colored layer on the partition layer on which the reverse pattern of the first colored layer is formed After applying the colored resist, a first color filter pattern composed of a plurality of first colored layers is formed by a photolithography method using a photomask for the first colored layer. In addition, by adjusting at least one of the exposure amount and the development time in the photolithography method, the upper end of the first color filter pattern protrudes on the reverse pattern of the first colored layer formed on the partition wall layer. The fourth step and the first color filter pattern as a mask are dry-etched on the partition layer to form reverse patterns of the second and third colored layers on the partition layer, and are provided around each colored layer. After applying the colored resist of the second colored layer on the fifth step of forming the partition, the partition layer on which the reverse pattern of the second and third colored layers is formed, and the first color filter pattern, A second color filter pattern composed of a plurality of second colored layers is formed by photolithography using a photomask for the second colored layer, and third The sixth step of forming the reverse pattern of the colored layer again, and the third color on the partition layer, the first color filter pattern, and the second color filter pattern on which the reverse pattern of the third colored layer is formed After applying the color resist of the layer, a color filter is formed by forming a third color filter pattern composed of a plurality of third colored layers by photolithography using a photomask for the third colored layer. And a seventh step of forming.

  According to one embodiment of the present invention, it is possible to provide a method for manufacturing a color filter for a solid-state imaging device capable of forming a partition wall having a narrow width and excellent dimensional accuracy while reducing the number of photomasks.

It is sectional drawing showing the structure of a color filter. It is a sectional side view for demonstrating the manufacturing method of a color filter. It is a sectional side view for demonstrating the manufacturing method of a solid-state image sensor.

Embodiments according to the present invention will be described below.
FIG. 1 is a cross-sectional view showing the structure of the color filter 17. 2A to 2O are side cross-sectional views for explaining a method for manufacturing the color filter 17.

(Configuration of solid-state imaging device and color filter 17)
As shown in FIG. 1, the solid-state imaging device is formed by laminating a protective film 2 and a color filter 17 in this order on a semiconductor substrate 1 on which photoelectric conversion devices are formed. The color filter 17 includes a plurality of colored layers that transmit light in a predetermined wavelength range, and a partition wall 9 provided around each of the plurality of colored layers. In this embodiment, it has the 1st colored layer 3, the 2nd colored layer 5, and the 3rd colored layer 7 as a some colored layer. Further, just one colored layer of the plurality of colored layers 3, 5, 7 is laminated immediately above the partition wall 9. In the present embodiment, the first colored layer 3 is used as one colored layer.

(Manufacturing method of the color filter 17)
Next, the manufacturing method of the color filter for solid-state image sensors is demonstrated.
First, in the first step, as shown in FIG. 2A, a protective film 2 and a partition wall layer 10 are laminated (deposited) in this order on a semiconductor substrate 1 on which a photoelectric conversion element is formed.
Next, in the second step, a positive photoresist 11 is applied on the partition wall layer 10. Next, as shown in FIG. 2B, a resist pattern having a reverse pattern of the first colored layer 3 is formed on the positive photoresist 11 by photolithography using the photomask 4 for the first colored layer 3. Form. The photomask 4 is a mask that transmits exposure light only to the formation region of the first colored layer 3. Specifically, the positive photoresist 11 is exposed using the photomask 4 for the first colored layer 3, and the exposed positive photoresist 11 is developed as shown in FIG. Thus, a resist pattern is formed.

Next, in the third step, as shown in FIG. 2D, the partition layer 10 is dry-etched using the resist pattern formed in the second step as a mask, and then the resist pattern is peeled and washed. A reverse pattern of the first colored layer 3 is formed on the partition layer 10.
Next, in a 4th process, as shown in FIG.2 (e), the coloring resist of the 1st colored layer 3 is apply | coated to the partition layer 10 in which the reverse pattern of the 1st colored layer 3 was formed. Next, a first color filter pattern is formed on the colored resist by photolithography using the photomask 4 for the first colored layer 3, that is, the mask used in the second step. Specifically, using the photomask 4 for the first colored layer 3, the colored resist of the first colored layer 3 is exposed, and as shown in FIG. 2 (f), the exposed first colored resist is exposed. Is developed to form a first color filter pattern composed of a plurality of first colored layers 3.

  At that time, by adjusting at least one of the exposure amount and the development time in the photolithography method, the upper end of the first color filter pattern is put on the reverse pattern of the first colored layer 3 formed on the partition layer 10. Let me. Thereby, the pixel size of the first color filter pattern is made larger than the pixel size of the reverse pattern of the first colored layer 3.

  Next, in the fifth step, as shown in FIG. 2G, the partition layer 10 is dry-etched using the first color filter pattern formed in the fourth step as a mask, and the partition layer 10 is subjected to the second and second steps. The reverse pattern of the third colored layers 5 and 7 is formed. Thereby, the partition wall 9 provided around each of the colored layers 3, 5, 7 is formed in the partition layer 10. In the dry etching, the first colored layer 3 is laminated directly on the partition wall 9. The reverse patterns of the second and third colored layers 5 and 7 may be formed using a negative photoresist instead of the first colored layer 3. In this case, after the reverse patterns of the second and third colored layers 5 and 7 are formed, the negative photoresist is peeled and washed, and then the first color filter pattern is removed from the colored resist of the first colored layer 3. Steps up to the formation of are performed.

  Next, in the sixth step, as shown in FIG. 2 (h), the partition layer 10 in which the reverse patterns of the second and third colored layers 5 and 7 are formed in the fifth step, and the fourth step is formed. A colored resist for the second colored layer 5 is applied on the first color filter pattern thus formed. Next, a second color filter pattern composed of a plurality of second colored layers 5 is formed on the colored resist by photolithography using the photomask 6 for the second colored layer 5. The photomask 6 is a mask that transmits exposure light only to the formation region of the second colored layer 5. Specifically, using the photomask 6 for the second colored layer 5, the colored resist of the second colored layer 5 is exposed, and the exposed colored resist is developed as shown in FIG. 2 (i). Thus, the second color filter pattern is formed in the concave portion of the reverse pattern of the second colored layer 5. The photomask 6 is a mask that transmits exposure light only to the formation region of the third colored layer 7. At that time, in the photolithography method, the reverse pattern of the third colored layer 7 is formed again.

  Next, in the seventh step, as shown in FIG. 2 (j), the partition layer 10 in which the reverse pattern of the third colored layer 7 is formed in the sixth step, and the first color formed in the fourth step. The colored resist of the third colored layer 7 is applied onto the filter pattern and the second color filter pattern formed in the sixth step. Next, a third color filter pattern composed of a plurality of third colored layers 7 is formed on the colored resist by photolithography using the photomask 8 for the third colored layer 7. Specifically, using the photomask 8 for the third colored layer 7, the colored resist of the third colored layer 7 is exposed, and the exposed colored resist is developed as shown in FIG. Thus, the third color filter pattern is formed in the concave portion of the reverse pattern of the third colored layer 7. Thereby, the color filter 17 having the first, second and third color filter patterns and the partition walls 9 is formed.

(Effect of this embodiment)
The invention according to this embodiment has the following effects.
(1) The manufacturing method of the color filter 17 which concerns on this embodiment is, after apply | coating the coloring resist of the 1st colored layer 3 to the partition layer 10 in which the reverse pattern of the 1st colored layer 3 was formed, 1st A first color filter pattern composed of a plurality of first colored layers 3 is formed by a photolithography method using a photomask 4 for the colored layer 3, and at least one of an exposure amount and a development time in the photolithography method. And adjusting the first color filter pattern so that the upper end of the first color filter pattern protrudes on the reverse pattern of the first colored layer 3 formed on the partition wall layer 10, and using the first color filter pattern as a mask The partition layer 10 is dry-etched to form reverse patterns of the second and third colored layers 5 and 7 on the partition layer 10, and around the colored layers 3, 5 and 7. And a fifth step of forming a partition wall provided.
According to such a configuration, the manufacturing method of the color filter 17 capable of forming the partition wall 9 having a small width and excellent dimensional accuracy without increasing the number of photomasks used in the conventional color filter manufacturing method by the photolithography method. Can provide.

(2) The color filter 17 according to the present embodiment is provided around each of the plurality of colored layers 3, 5, 7 that transmits light in a predetermined wavelength range, and the plurality of colored layers 3, 5, 7. The partition wall 9 is provided. Then, just above the partition wall 9, only one colored layer (first colored layer 3) selected from among the plurality of colored layers 3, 5, 7 is laminated.
According to such a configuration, it is possible to provide the color filter 17 having a relatively high aperture ratio while suppressing color mixing due to the entrance of light from the adjacent colored layer.

(3) A solid-state image sensor according to this embodiment includes the color filter for a solid-state image sensor described in (2) above.
According to such a configuration, color mixing can be suppressed, and a highly sensitive solid-state imaging device can be provided.

Examples according to the present invention will be described below.
First, in the first step, as shown in FIG. 2A, a coating liquid containing an acrylic resin is spin-coated on a semiconductor substrate 1 on which a photoelectric conversion element is formed, and heated at 230 ° C. for 10 minutes on a hot plate. A protective film 2 having a thickness of 0.13 μm was formed by processing, and then a partition layer 10 made of a silicon oxide film was formed on the protective film 2 to a thickness of 0.8 μm by a CVD method.

  Next, in the second step, a positive type i-line photoresist (TDMR-AR80: manufactured by Tokyo Ohka Kogyo Co., Ltd.) is spin-coated on the partition wall layer 10 and prebaked at 90 ° C. for 1 minute. 11 was formed to a thickness of 1 μm. Next, as shown in FIG. 2B, the positive photoresist 11 was exposed by an i-line stepper exposure machine using the photomask 4 for the first colored layer 3. Next, as shown in FIG. 2C, the exposed positive photoresist 11 was developed with an aqueous 2.38% TMAH (tetramethylammonium hydride) solution for 1 minute. Thereby, a resist pattern having a reverse pattern of the first colored layer 3 was formed on the partition wall layer 10.

  Next, in the third step, as shown in FIG. 2D, dry etching is performed on the partition wall layer 10 using a fluorocarbon gas using the resist pattern of the reverse pattern formed in the second step as a mask. The reverse pattern of the first colored layer 3 was formed on the layer 10. The resist pattern was peeled and washed using NMP (N-methyl-2-pyrrolidone).

  Next, in the fourth step, as shown in FIG. 2 (e), a green resist is spin-coated on the partition layer 10 on which the reverse pattern of the first colored layer 3 is formed in the third step. Pre-baking was performed to form a colored resist of the first colored layer 3 with a thickness of 1.5 μm, and the photomask 4 for the first colored layer 3 was used and exposed by an i-line stepper. Next, as shown in FIG. 2 (f), the colored resist exposed to the first colored layer 3 is developed with a 1.19% TMAH aqueous solution for 1 minute, and then baked on a hot plate at 230 ° C. for 3 minutes. One color filter pattern was formed. The exposure amount was set so that the pixel size of the first color filter pattern was larger than the pixel size of the reverse pattern of the first colored layer 3 formed on the partition layer 10. The pixel size of the first color filter pattern may be adjusted using the development time, or may be adjusted using both the exposure time and the development time.

  Next, in the fifth step, as shown in FIG. 2G, dry etching is performed on the partition wall layer 10 using a fluorocarbon gas using the first color filter pattern formed in the fourth step as a mask. A reverse pattern of the second and third colored layers 5 and 7 was formed on the partition wall layer 10. The height h1 of the first color filter pattern need only be higher than the height h2 of the partition wall 9 and cover the upper end of the partition wall 9. The film thickness of the first colored layer 3 is dry. You may set arbitrarily by the selection ratio of the 1st colored layer 3 and the partition layer 10 in an etching. The height h1 of the partition wall 9 is preferably at least three quarters of the height h2 of the first color filter pattern. Further, as a gas for dry etching, a mixed gas with a chlorine-based gas, a halogen gas, hydrogen, nitrogen, oxygen, a rare gas, or the like may be used in addition to the fluorine-based gas.

  Next, in the sixth step, as shown in FIG. 2 (h), the partition layer 10 in which the reverse patterns of the second and third colored layers 5 and 7 are formed in the fifth step, and the fourth step is formed. A blue resist is spin-coated on the first color filter pattern, and pre-baked at 90 ° C. for 1 minute to form a colored resist of the second colored layer 5 with a thickness of 1 μm. The second colored layer 5 Using an i-line stepper, the photomask 6 was exposed. Next, as shown in FIG. 2I, the exposed colored resist was developed with a 1.19% TMAH aqueous solution and then baked on a hot plate at 230 ° C. for 3 minutes to form a second color filter pattern. At that time, the reverse pattern of the third colored layer 7 was again formed by exposure and development of the blue resist.

  Next, in the seventh step, as shown in FIG. 2 (j), the partition layer 10 in which the reverse pattern of the third colored layer 7 is formed in the sixth step, and the first color formed in the fourth step. A red resist is spin-coated on the filter pattern and the second color filter pattern formed in the sixth step, pre-baked at 90 ° C. for 1 minute, and the colored resist of the third colored layer 7 is applied in a thickness of 1 μm. Then, it was exposed with an i-line stepper using a photomask 8 for the third colored layer 7. Next, as shown in FIG. 2 (k), the exposed colored resist was developed with a 1.19% TMAH aqueous solution and then baked on a hot plate at 230 ° C. for 3 minutes to form a third color filter pattern. Thereby, the color filter 17 having the first, second and third color filter patterns and the partition walls 9 was formed.

  Next, in the eighth step, as shown in FIG. 3A, a coating liquid containing an acrylic resin is spin-coated on the color filter 17, and a heat treatment is performed at 230 ° C. for 10 minutes on a hot plate to obtain a. A planarizing layer 13 having a thickness of 13 μm was formed. Next, an acrylic photosensitive resin was spin-coated on the formed flattening layer 13 and baked at 90 ° C. for 1 minute to form a transparent resin layer 14. Next, as shown in FIG. 3B, the formed transparent resin layer 14 was exposed by an i-line stepper using a microlens photomask 15. Next, as shown in FIG. 3C, the exposed transparent resin layer 14 is developed with a 1.19% TMAH aqueous solution, and as shown in FIG. 3D, the developed transparent resin layer 14 is developed at 230 ° C. Bake for 10 minutes. Thereby, the solid-state imaging device was formed (manufactured) by forming the microlens 16.

  According to the present invention, a partition wall having a small width and excellent dimensional accuracy can be formed without increasing the number of photomasks used in a conventional color filter manufacturing method by photolithography, and light enters from adjacent pixels. It is possible to provide a color filter for a solid-state imaging device and a solid-state imaging device with little color mixing and a high aperture.

DESCRIPTION OF SYMBOLS 1 ... Semiconductor substrate 2 ... Protective film 3 ... 1st colored layer 4 ... Photomask 5 for 1st colored layers ... 2nd colored layer 6 ... 2nd Photomask 7 for colored layer ... Third colored layer 8 ... Photomask 9 for third colored layer ... Partition 10 ... Partition layer 11 ... Positive photoresist 12 ... Photomask 13 for barrier ribs ... Flattening layer 14 ... Transparent resin layer 15 ... Photomask 16 for microlenses ... Microlens

Claims (3)

A first step of laminating a protective film and a partition layer in this order on the semiconductor substrate on which the photoelectric conversion element is formed;
After applying a positive photoresist on the partition layer, a resist pattern having a reverse pattern of the first colored layer is applied to the positive photoresist by a photolithography method using a photomask for the first colored layer. A second step of forming;
A third step of performing dry etching on the partition layer using the resist pattern as a mask, and forming a reverse pattern of the first colored layer on the partition layer;
After applying the colored resist of the first colored layer to the partition layer on which the reverse pattern of the first colored layer is formed, a plurality of photolithography methods using a photomask for the first colored layer are used. Forming a first color filter pattern comprising the first colored layer and adjusting at least one of an exposure amount and a development time in the photolithography method so that the upper end of the first color filter pattern is positioned on the partition layer. A fourth step of protruding on the reverse pattern of the first colored layer formed in
Using the first color filter pattern as a mask, the partition wall layer is dry-etched to form reverse patterns of the second and third colored layers on the partition layer, and the partition walls provided around each colored layer A fifth step of forming,
After applying the coloring resist of the second colored layer on the partition layer on which the reverse patterns of the second and third colored layers are formed, and the first color filter pattern, the second coloring A sixth step of forming a second color filter pattern composed of a plurality of the second colored layers and again forming a reverse pattern of the third colored layer by a photolithography method using a photomask for the layers; When,
After applying the colored resist of the third colored layer on the partition layer, the first color filter pattern, and the second color filter pattern on which the reverse pattern of the third colored layer is formed, A seventh step of forming a color filter by forming a third color filter pattern comprising a plurality of the third colored layers by a photolithography method using a photomask for the third colored layer; A method for producing a color filter for a solid-state imaging device, comprising: A plurality of colored layers that transmit light in a predetermined wavelength range;
A partition provided around each of the plurality of colored layers,
A color filter for a solid-state imaging device, wherein only one colored layer selected from the plurality of colored layers is laminated immediately above the partition.   A solid-state imaging device comprising the color filter for a solid-state imaging device according to claim 2.

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