JP2009244710A - Color filter array and method of manufacturing the same, and solid-state image sensor - Google Patents

Abstract

An end point of a planarization process (etchback process) is easily specified.
A color filter layer is formed on a semiconductor substrate. A transparent film 29 is formed on the color filter layer 28B. The color filter layer 28B is patterned to form the B color filter layer 13B and the transparent film 14 on the semiconductor substrate 18, and the region 18a for forming the R color filter layer 13R is formed. The color filter layer 28R is formed so as to cover the entire surface of the semiconductor substrate 18. The color filter layer 28R is etched back. If the plasma emission of SiF generated when the transparent film 14 is etched back is detected, it is determined that the etch back processing has reached the end point. By using the transparent film 14 for end point detection of the etch back process, the end point of the etch back process can be easily specified.
[Selection] Figure 1

Description

  The present invention relates to a color filter array in which a plurality of color filter layers are two-dimensionally arranged on a substrate, a method for manufacturing the same, and a solid-state imaging device including the color filter array.

  For liquid crystal display devices and solid-state imaging devices, a color filter array in which a plurality of color filter layers of blue (B), red (R), and green (G) are two-dimensionally arranged on a substrate such as a semiconductor substrate or a glass substrate. Is provided. As a method for producing such a color filter array, a pigment dispersion method is often used (see Patent Documents 1 to 5). In the pigment dispersion method, since a pigment is used as the color filter material, the obtained color filter array is excellent in light resistance and heat resistance.

  In the pigment dispersion method, a color filter material of the first color (for example, B color) is applied on a substrate using a spin coater or a roll coater, and then dried to form a coating film layer. A B color filter layer is formed by patterning using a photolithography method, a dry etching method, or the like (see Patent Documents 6 to 8).

  Next, a second color (for example, R color) color filter material is applied and dried on the entire surface of the substrate to form a coating layer covering the entire surface of the substrate including the B color filter layer. Then, the surface of the coating layer is flattened by an etch back method or a chemical mechanical polishing (CMP) method until the surface of the coating layer and the surface of the B color filter layer are flush with each other. Thus, an R color filter layer is formed (see Patent Document 9).

Then, after patterning the flattened R color filter layer to form a third color (G color) color filter layer on the glass substrate, the same as the R color filter layer The color filter layer of G color is formed by the forming method. Thereby, the color filter layers of B color, R color, and G color are two-dimensionally arranged on the glass substrate.
JP-A-2-181704 JP-A-2-199403 Japanese Patent Laid-Open No. 5-273411 JP-A-7-140654 JP 2005-326453 A JP-A-55-146406 JP 2001-249218 A JP 2003-332310 A JP 2006-351786 A

  By the way, in the above-mentioned patent document 9, when forming a color filter layer for the second and subsequent colors, a coating layer is formed on the glass substrate so as to cover the previously formed color filter layer, and then this coating layer is formed. An example in which the surface of the layer is planarized until it is flush with the surface of the previously formed color filter is disclosed. However, since Patent Document 9 does not describe a specific example for specifying the end point of etch back or CMP, the coating layer remains on the previously formed color filter (residual film).

  For example, if the coating layer is excessively shaved by etch back or CMP, the thickness of each color filter becomes thinner than a desired thickness. As a result, the amount of light transmitted through the color filters of each color changes, so that the optical characteristics of the color filters of each color change. Further, if another color coating layer remains on the previously formed color filter layer, the optical characteristics of the color filter change.

  The present invention is intended to solve the above-described problem, a color filter array that can easily identify the end point of the flattening process performed when forming the color filters for the second and subsequent colors, and a manufacturing method thereof, and An object of the present invention is to provide a solid-state imaging device including a color filter array.

  In order to achieve the above object, the present invention provides a method for manufacturing a color filter array in which a plurality of color filter layers are formed for each color on a surface of a substrate and arranged two-dimensionally. A first step of forming a color filter layer of color, a second step of forming a transparent film including at least one of silicon oxide and metal oxide on the color filter layer of the first color, A third step of patterning the first color filter layer and the transparent film to form a region for forming a second color filter layer on the surface of the substrate; and the second color A fourth step of forming the color filter layer of the second color so as to cover the surface of the substrate on which a region for forming the filter layer is formed; and a surface of the color filter layer of the second color. It characterized by having at least a fifth step of planarization treatment until the transparent film is exposed.

  The flattened Nth (N is a natural number of 2 or more) color filter layer is patterned to form a region for forming a (N + 1) th color filter layer on the surface of the substrate. And a seventh step of forming the (N + 1) th color filter layer so as to cover the surface of the substrate on which the region for forming the (N + 1) th color filter layer is formed. It is preferable to include a step and an eighth step of planarizing the surface of the (N + 1) th color filter layer until the transparent film is exposed.

  The planarization process is preferably performed by an etch back process or a chemical mechanical polishing process. The etch-back process is performed using a plasma gas, and the exposure of the transparent film is determined by plasma emission of a reaction product generated by etching the transparent film after the etch-back process is started. It is preferable to carry out by detecting with a spectroscopic device.

  The patterning is preferably performed using a dry etching method. The transparent film is preferably formed by a sol-gel method using a precursor polymer coating solution containing at least one of silicon oxide and metal oxide.

  The transparent film preferably has a refractive index substantially equal to the refractive index of the first color filter layer. Furthermore, the refractive index of the transparent film is preferably 1.4 to 1.8. Moreover, it is preferable that the film thickness of the said transparent film is formed by 50 nm-2000 nm.

  The color filter array of the present invention is manufactured by the method for manufacturing a color filter array according to any one of claims 1 to 9.

  The thickness of the transparent film is preferably 50 nm to 200 nm.

  A solid-state imaging device according to the present invention includes the color filter array according to claim 10.

  In the present invention, a transparent film is formed on the color filter layer formed for the first color, and the formed transparent film is used for end point detection when the color filter layer for the second color is formed by the planarization process. Therefore, the end point of the planarization process can be easily specified. Accordingly, when the second color filter layer is formed, excessive cutting or residual film (a color filter layer of another color remains on the previously formed color filter layer) is prevented. Further, the film thicknesses of the color filter layers of the first color and the second color can be made uniform. As a result, a color filter array having excellent optical characteristics can be obtained.

  As shown in FIG. 1, the solid-state imaging device 10 includes photodiodes 12 </ b> B, 12 </ b> R, 12 </ b> G, a color filter array 13, a transparent film 14, a planarization film 15, a microlens 16, and other parts provided on a semiconductor substrate 18. Composed.

  The photodiodes 12 </ b> B, 12 </ b> R, and 12 </ b> G are photoelectric conversion elements that photoelectrically convert light from a subject, and are two-dimensionally arranged on the semiconductor substrate 18. A color filter array 13 is provided on the photodiodes 12B, 12R, and 12G.

  The color filter array 13 includes a B color filter layer 13B, an R color filter layer 13R, and a G color filter layer 13G provided on the photodiodes 12B, 12R, and 12G, respectively. The photodiodes 12B, 12R, and 12G photoelectrically convert the B light, R light, and G light transmitted through the B color filter layer 13B, the R color filter layer 13R, and the G color filter layer 13G, respectively.

  As shown in FIG. 2, the color filter layers 13B, 13R, and 13G for the respective colors are also two-dimensionally arranged in the same manner as the photodiodes 12B, 12R, and 12G. The G color filter layer 13G (photodiode 12G) is arranged in a checkered pattern. The R color filter layer 13R (photodiode 12R) and the G color filter layer 13G (photodiode 12G) are arranged between the G color filter layers 13G. Note that the arrangement of the color filter layers (photodiodes) is not limited to this.

Returning to FIG. 1, the transparent film 14 is formed on the B color filter layer 13B that is formed first among the color filter layers 13B, 13R, and 13G of the respective colors. This transparent film 14 contains SiO ₂ (silicon oxide, silicon oxide), and is used to detect the end point of the etch-back process (see FIG. 11) performed when the R color and G color filter layers 13R and 13G are formed. It is done. Since the transparent film 14 is transparent to light in the visible region, even if it is formed on the B color filter layer 13B, it does not affect the optical characteristics of the B color filter layer 13B.

  The planarizing film 15 is formed so as to cover the surfaces (upper surfaces) of the R color filter layer 13R, the G color filter layer 13G, and the transparent film 14, and has a flat upper surface. The microlens 16 is a lens provided with the convex surface upward, and is provided on the upper surface of the planarizing film 15. The microlens 16 is provided at a position corresponding to each of the photodiodes 12B, 12R, and 12G, and efficiently guides light from the subject to each of the photodiodes 12B, 12R, and 12G.

  In addition to the photodiodes 12B, 12R, and 12G described above, the semiconductor substrate 18 covers other than the well-known transfer electrodes formed of polysilicon and the portions where the photodiodes 12B, 12R, and 12G are formed. A light shielding mask or the like is provided.

  Next, the color filter array forming step 20 for forming the color filter array 13 of the present invention will be described with reference to FIG. The color filter array forming step 20 is roughly composed of a B color filter layer forming step 21, an R color filter layer forming step 22, and a G color filter layer forming step 23.

  The B color filter layer forming step 21 includes a coating / drying step 25, a transparent film forming step 26, and a patterning step 27. In the coating and drying step 25, the color filter material of the B color filter layer 13B is coated and dried (heated) on the entire surface of the semiconductor substrate 18 to form the color filter layer 28B (see FIG. 5). The color filter layer 28 </ b> B is a B color filter layer formed so as to cover the entire surface of the semiconductor substrate 18.

  In the transparent film forming step 26, a transparent film 29 (see FIG. 6) is formed using a sol-gel method so as to cover the entire surface of the color filter layer 28B. The transparent film 29 is a transparent film formed so as to cover the entire surface of the color filter layer 28B. In the patterning step 27, the color filter layer 28B and the transparent film 29 are patterned using a dry etching method. Thus, the B color filter layer 13B and the transparent film 14 are formed, and a region for forming the R color filter layer 13R is formed on the surface of the semiconductor substrate 18.

  The R color filter layer forming step 22 includes a coating / drying step 30 and an etch-back step 31. In the coating and drying step 30, the color filter material of the R color filter layer 13R is applied and dried on the entire surface of the semiconductor substrate 18 on which the B color filter layer 13B and the transparent film 14 are formed, and the color filter layer 28R ( 9). The color filter layer 28 </ b> R is an R color filter layer formed so as to cover the entire surface of the semiconductor substrate 18.

  In the etch back step 31, the entire surface of the color filter layer 28R is etched back (entire etching process, see FIG. 5) using plasma gas. This etch-back process is performed until the transparent film 14 is exposed. Specifically, when the transparent film 14 is exposed by an etch-back process using a plasma gas, and the exposed transparent film 14 is further etched by the plasma gas, a reaction product (hereinafter, simply referred to as “etched reaction product”) is generated. Plasma emission of reaction product) occurs. Therefore, when the plasma emission of the reaction product of the transparent film 14 is detected, it is determined that the transparent film 14 is exposed, and the etch-back process is completed. That is, the transparent film 14 is used for end point detection of the etch back process (see FIG. 13).

  When the transparent film 14 is exposed by the etch-back process, the surface of the color filter layer 28R and the surface of the previously formed B color filter layer 13B (transparent film 14) are substantially flush, and the R color filter Layer 13R is formed. In this way, in the etch back step 31, the entire surface of the color filter layer 28R is planarized by the etch back method until the transparent film 14 is exposed.

  The G color filter layer forming step 23 includes a patterning step 33, a coating / drying step 34, and an etch-back step 35. In the patterning step 33, the R color filter layer 13R formed in the region where the G color filter layer 13G is formed is removed. Thus, a region for forming the G color filter layer 13G is formed on the semiconductor substrate 18.

  In the coating and drying step 34, the color filter material of the G color filter layer 13G is applied and dried on the entire surface of the semiconductor substrate 18 on which the B color filter layer 13B (transparent film 14) and the R color filter layer 13R are formed. Then, the color filter layer 28G (see FIG. 15) is formed. The color filter layer 28G is a G color filter layer formed so as to cover the entire surface of the semiconductor substrate 18.

  In the etch-back process 35, as in the above-described etch-back process 31, the entire surface of the color filter layer 28G is etched back until the transparent film 14 is exposed. The surface of the color filter layer 28G and the surface of the previously formed B color filter layer 13B (transparent film 14) are substantially flush with each other, whereby the G color filter layer 13G is formed. Thus, the color filter array 13 in which the color filter layers 13B, 13R, and 13G of the respective colors are two-dimensionally arranged on the semiconductor substrate 18 is formed.

  Next, the dry etching apparatus 41 used for the etch back process will be described with reference to FIG. As the dry etching apparatus 41, for example, RIE-ECR: U-621 (manufactured by Hitachi High-Technologies Corporation) is used. The dry etching apparatus 41 is also used for the dry etching process of the patterning steps 27 and 33.

  The dry etching apparatus 41 is roughly divided into a chamber 42, a mixed gas supply unit 43, an RF oscillator 44, a plasma emission intensity diagnostic monitor 46, and a control unit 47 that controls operations of these units. In the chamber 42, a planar electrode 48 on which the semiconductor substrate 18 is installed, and a counter electrode 49 provided above the planar electrode 48 are provided. Further, the chamber 42 is provided with a gas supply path 50 for supplying the aforementioned mixed gas into the chamber 42 from the mixed gas supply unit 43 and an observation window 51 for observing plasma emission.

  The planar electrode 48 and the counter electrode 49 are each connected to the RF oscillator 44. A blocking capacitor 52 is provided between the planar electrode 48 and the RF oscillator 44. When a high frequency voltage is applied between the planar electrode 48 and the counter electrode 49 by the RF oscillator 44 in a state where the mixed gas is supplied from the etching gas supply unit 43 into the chamber 42, plasma gas is generated between the electrodes 48 and 49. appear.

  The electrons in the generated plasma gas immediately gather on the planar electrode 48 and the counter electrode 49, respectively. Since the counter electrode 49 is connected to the ground 53, the potential does not change even if electrons are collected. On the other hand, since the DC current is blocked by the blocking capacitor 52, the flat electrode 48 accumulates electrons and has a negative potential. When the planar electrode 48 becomes negative potential in this way, positive ions in the plasma gas are attracted to the planar electrode 48 (negative potential). As a result, positive ions in the plasma gas are perpendicularly incident on the entire surface of the color filter layers 28R and 28G of the semiconductor substrate 18, so that the color filter layers 28R and 28G are entirely anisotropic etched, that is, etched back. .

  For example, HR4000 (manufactured by Ocean Optics) or C7640 (manufactured by Hamamatsu Photonics) is used as the plasma emission intensity diagnostic monitor (hereinafter simply referred to as “diagnostic monitor”) 46. The diagnostic monitor 46 includes a detector 46a connected by an optical fiber cable. The detector 46 a is disposed at a position facing the observation window 51 of the chamber 42. The detector 46 a detects plasma emission generated in the chamber 42, converts it into a voltage signal, and outputs it to the diagnostic monitor 46.

  Next, each step constituting the color filter array forming step 20 will be described in detail. However, the present invention is not limited to the following description.

[B color filter layer forming step]
As shown in FIG. 5, in the coating / drying step 25, a B coat color is used on a semiconductor substrate 18 (photodiodes 12B, 12R, and 12G are not shown) using a spin coater (SCWC80A: manufactured by Dainippon Screen Mfg. Co., Ltd.). A color filter material for the filter layer 13B is applied. Next, the color filter material is cured by heat-treating the semiconductor substrate 18 with a known heating device such as a hot plate or an oven under the heating conditions of an atmospheric temperature of 200 ° C. to 250 ° C. and a heating time of 5 to 10 minutes. Thereby, the color filter layer 28 </ b> B is formed on the semiconductor substrate 18.

  The heat treatment is performed at a temperature of 130 ° C. to 300 ° C., preferably a temperature of 150 ° C. to 280 ° C., more preferably a temperature range of 170 ° C. to 260 ° C., and 10 seconds to 3 hours, preferably 30 seconds to 2 hours. More preferably, it can be performed in a time range of 60 seconds to 60 minutes. However, considering productivity, the time required for curing is preferably short. In addition, a drying process may be performed before the heat treatment.

  The film thickness of the color filter layer 28B (B color filter layer 13B) formed in the coating and drying step 25 is 0.05 μm to 0.9 μm, preferably 0.07 μm, from the viewpoint of the function as a color filter and thinning. It is formed so as to be within a range of ˜0.8 μm, more preferably 0.1 μm to 0.7 μm.

As shown in FIG. 6, in the transparent film forming step 26, a transparent film 29 is formed by a sol-gel method using a precursor polymer containing at least silicon oxide (SiO ₂ ). The sol-gel method is a method in which a precursor polymer (sol) is made into a gel that loses fluidity by hydrolysis and polycondensation reaction, and this gel is heated to obtain an oxide film (transparent film 29).

  By using the sol-gel method, the transparent film 29 can be formed using the above-described spin coater (rotary coating), roll coater (roll coating), slit coater (slit coating), and die coater (casting coating). That is, the transparent film 29 can be formed by the same formation method as that for the color filter layers 28B, 28R, and 28G. Therefore, the production facilities for the color filter layers 28B, 28R, 28G and the transparent film 29 can be integrated in one place. As a result, production efficiency can be improved.

Although the SiO ₂ film corresponding to the transparent film 14 can be formed by, for example, a chemical vapor deposition (CVD) apparatus, the formation method differs from the color filter layers 28B, 28R, and 28G. It is difficult to consolidate manufacturing facilities in one place, and the production efficiency is inferior when compared with this embodiment.

  Further, the sol-gel method can form the transparent film 14 (transparent film 29) at a lower temperature than the CVD method. On the other hand, in the CVD method, since the semiconductor substrate 18 needs to be heated to about 900 ° C., the optical characteristics of the B color filter layer 13B may change. Further, the sol-gel method can form a film at a lower cost than the CVD method or the like.

  The sol-gel method can easily adjust the refractive index of the transparent film 14 by adjusting the components of the precursor polymer. For example, if the refractive index of the transparent film 14 is different from that of the B color filter layer 13B, light incident from the outside is easily reflected at the interface between the two, so that the light transmittance of the B color filter layer 13B is reduced. End up. For this reason, in the present embodiment, the refractive index of the transparent film 14 is adjusted to be the same as that of the B color filter layer 13B. The refractive index of the transparent film 14 is preferably 1.5 to 1.7, more preferably 1.55 to 1.65.

  Furthermore, the sol-gel method can easily adjust the etching rate of the transparent film 14 by adjusting the components of the precursor polymer. As described above, the end point of the etch-back process (planarization process) is detected by detecting the generation of plasma emission of the reaction product of the transparent film 14 etched by the plasma gas. At this time, if the etching rate of the transparent film 14 becomes too high, the transparent film 14 is removed immediately after the etch-back process, making it difficult to detect the plasma emission of the reaction product. On the other hand, if the etching rate of the transparent film 14 becomes too low, the amount of reaction product generated decreases, making it difficult to detect plasma emission of the reaction product. For this reason, in the present embodiment, the etching rate of the transparent film 14 is adjusted to be higher than that of the R and G color filter layers 13R and 13G and not to be too high.

  In the transparent film forming step 26, the precursor polymer is applied onto the color filter layer 28B using the above-described spin coater. Next, the semiconductor substrate 18 is heat-treated by the above-described known heating device under the heating conditions of an atmospheric temperature of 200 ° C. to 250 ° C. and a heating time of 5 to 10 minutes, and the precursor polymer is cured (gelled). Thereby, the transparent film 29 is formed on the color filter layer 28B. The temperature range and time range of the heat treatment are the same as those in the coating and drying step 25 described above.

  The film thickness of the transparent film 29 (transparent film 14) is 0.01 μm to 0.2 μm, more preferably 0.05 μm to 0.1 μm. This is because when the film thickness of the transparent film 14 is less than 0.01 μm, the transparent film 14 is immediately removed by the etch-back process, and it is difficult to detect the plasma emission of the reaction product. In other words, if the film thickness of the transparent film 14 is secured to 0.01 μm or more, the plasma emission of the reaction product of the transparent film 14 can be detected, so that the end point of the etch back process can be detected.

  In addition, the reason why the film thickness of the transparent film 29 (transparent film 14) is 0.2 μm or less is as follows. As described above, the transparent film 14 remains on the upper surface of the B color filter layer 13B of the finished color filter array 13. For this reason, when the film thickness of the transparent film 14 exceeds 0.2 μm, the reflectance at which the transparent film 14 reflects light incident from the outside increases, and the light transmittance of the B color filter layer 13B decreases. . In other words, if the film thickness of the transparent film 14 is suppressed to 0.2 μm or less, reflection of light by the transparent film 14 can be suppressed and a decrease in the light transmittance of the B color filter layer 13B can be suppressed.

The precursor polymer is represented by the general formula Si (OR ¹ ) _a or R ² _b Si (OR ³ ) _c , and has one or more metal alkoxide derivatives selected from these partial hydrolysates or condensates as a main component. It is manufactured by dissolving it in an organic solvent. In addition, a metal atom selected from Ti, Ta, Zn, and Zr may be included. When adjusting the refractive index and the etching rate of the transparent film 14 as described above, it is preferable that silicon oxide is contained in an amount of less than 30 to 100%, more preferably 50% to 95%, and further more preferably 70% to 90%. % Or less is particularly preferable. Moreover, the refractive index of the transparent film 14 can be adjusted by adjusting the mixing amount of Ti (TiO ₂ ) having a high refractive index. Specifically, the refractive index of the transparent film 14 can be increased as the mixing amount of TiO ₂ is increased. Moreover, when the mixing amount of TiO ₂ is excessive, the etching rate is lowered, and it becomes difficult to detect the end point as described above.

^{Further, R 1, R 2, R} 3 in formula are each independently an alkyl group having 1 to 8 carbon atoms, a methyl group, an ethyl group, an isopropyl group, n- butyl group, an isobutyl group, n- amyl Group and octyl group. Therefore, hydrophilicity becomes high by the OH group generated by hydrolysis of a part of each of these alkyl groups. Thereby, the adhesiveness of the transparent film 14 and the B color filter layer 13B becomes high. In the above general formula, a is the valence of Si, b and c are each an integer of 1 or more, and b + c is the valence of M. As such a precursor polymer, for example, VR1 and VR7 manufactured by Rasa Industry Co., Ltd. are used.

  In the patterning step 27, the formation process of the photoresist layer 55, the exposure process, the development process, the dry etching process, and the peeling process of the photoresist layer 55 are sequentially performed. First, as shown in FIG. 7A, a positive photoresist (FHi622BC: manufactured by FUJIFILM Electronics Materials) is applied on the transparent film 29 using the above-described spin coater. Next, the semiconductor substrate 18 is pre-baked (at a temperature of 80 to 100 ° C. for 60 seconds) using a hot plate or the like. As a result, the photoresist is cured and a photoresist layer 55 is formed. In addition to the above, a known positive photoresist can be used as the photoresist. As the positive photoresist, there can be used a positive photosensitive resin composition that is sensitive to ultraviolet rays (g rays, i rays), far ultraviolet rays including excimer lasers such as KrF and ArF, and electron beams.

  When the photoresist layer 55 is formed, the exposure process is started. The light source used for exposure is preferably i-line (ultraviolet light having a wavelength of 365 nm) because the color filter pattern only needs to have a resolving power of about 1.0 μm. The i-line is applied to the photoresist layer 55 through a mask 56 (for example, a photomask) having a mask pattern substantially the same as the pattern of the B color filter layer 13B (see FIG. 2) and a stepper (not shown). Irradiation is performed to expose the photoresist layer 55. The i-line is irradiated outside the region where the B color filter layer 13B is formed.

  When the exposure processing is completed, the semiconductor substrate 18 is subjected to PEB (Post Exposure Bake) processing (temperature 100 ° C. to 120 ° C., 90 seconds) using a hot plate or the like. Next, after the semiconductor substrate (photoresist layer 55) is subjected to paddle development processing with a developer, PEB processing is further performed with a hot plate, and the photoresist other than the region where the B color filter layer 13B is formed is removed. As a result, as shown in (B), an opening 55a is formed in the region of the photoresist layer 55 where the R and G color filter layers 13R and 13G are to be formed. The developer is not particularly limited as long as it does not affect the B color filter layer 13B and the like and dissolves the exposed portion of the photoresist layer 55 and the uncured portion of the negative resist. For example, a combination of various organic solvents or an alkaline aqueous solution is used.

  When the development process and the PEB process are completed, as shown in (C), by using the mixed gas (plasma gas) in which the fluorocarbon gas and the oxygen gas are mixed by the dry etching apparatus 41 (see FIG. 3) described above, The color filter layer 28B and the transparent film 29 are anisotropically etched using the photoresist layer 55 as a mask (dry etching process). Thereby, the color filter layer 28B and the transparent film 29 which are exposed from the opening 55a of the photoresist layer 55, that is, other than the region where the B color filter layer 13B is formed, are removed by the etching process. Hereinafter, the etching conditions of the dry etching process will be described in detail.

[Mixed gas (plasma gas)]
The mixed gas used in the dry etching process is at least one fluorine-based gas from the viewpoint of processing (removing) the color filter layer 28B and the transparent film 29 (referred to as an etched portion) removed by the dry etching process into a rectangular shape. And at least oxygen gas.

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 (1)
N of Formula (1) represents 1-6, m represents 0-13, and 1 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 , Mention may be made of at least one selected from the group of CHF ₃ . As the fluorine-based gas used in the present embodiment, one kind of gas can be selected and used, or two or more kinds of gases can be used in combination. Furthermore, from the viewpoint of maintaining the rectangularity of the etched portion, it is preferable to select one of CF ₄ , C ₂ F ₆ , C ₄ F ₈ , and CHF ₃ , and at least CF ₄ and C ₂ F ₆ are selected. It is more preferable to select one of them, and it is particularly preferable to select CF ₄ .

  The mixed gas preferably has a flow rate ratio of 2/1 to 8/1 of the fluorine gas / oxygen gas content ratio (fluorine gas / oxygen gas). Thereby, adhesion of the etching product (reaction product) to the sidewall of the photoresist layer (wall surface of the opening 55a) during the etching process can be prevented, and the photoresist layer 55 can be removed during the peeling process of the photoresist layer 55 described later. Easy to peel. In particular, the content ratio of the fluorine-based gas and the oxygen gas is 2/1 to 6/1 in terms of preventing the re-deposition of the etching product to the photoresist sidewall while maintaining the rectangularity of the etched portion. It is preferable that the ratio is 3/1 to 5/1.

In addition to the fluorine-based gas and the oxygen gas, the mixed gas is further mixed with helium (He), neon (from the viewpoint of maintaining the partial pressure control stability of the etching plasma and the rectangular shape of the etched shape. Ne), argon (Ar), krypton (Kr), xenon (Xe) and other rare gases, and halogen gases containing halogen atoms such as chlorine atoms, fluorine atoms, bromine atoms (for example, CCl ₄ , CClF ₃ , AlF ₃ , AlCl _3, etc.), N ₂ , CO, and CO ₂ , preferably at least one of Ar, He, Kr, N 2, and Xe, more preferably He More preferably, at least one of Ar, Ar, and Xe is included. However, when it is possible to maintain the partial pressure control stability of the etching plasma and the rectangular shape of the shape to be etched, the mixed gas may consist only of a fluorine-based gas and an oxygen gas.

  In addition, the mixed gas has a gas content other than fluorine-based gas and oxygen gas, preferably 25 or less, more preferably 10 or more and 20 or less in terms of a flow ratio when oxygen gas is 1. It is particularly preferably 14 or more and 18 or less.

[Calculation method of etching time]
When performing the above-described dry etching treatment, it is preferable to obtain the etching treatment time in advance by the following method.
(1) The etching rate (nm / min) during the dry etching process is calculated.
(2) From the etching rate calculated in (1), the etching processing time required to etch a desired thickness during dry etching processing is calculated.

  The etching rate (1) can be calculated, for example, by measuring in advance data indicating the relationship between the etching time and the remaining film. Further, the etching processing time of (2) is preferably within 10 minutes, and more preferably within 7 minutes.

[Internal pressure of chamber]
During the dry etching process, the internal pressure of the chamber 42 (see FIG. 4) is preferably 2.0 to 6.0 Pa, and more preferably 4.0 to 5.0 Pa. Thereby, the rectangularity of the pattern (B color filter layer 13B) is improved, and adhesion of the sidewall protective film generated by etching to the photoresist can be suppressed. Further, the internal pressure of the chamber 42 can be adjusted by appropriately controlling the flow rate of the mixed gas and the degree of decompression of the chamber, for example.

[Semiconductor substrate temperature]
During the dry etching process, the temperature of the semiconductor substrate 18 is preferably 30 ° C. or higher and 100 ° C. or lower. Thereby, adhesion of the etching product to the side wall of the photoresist layer can be further suppressed, and the photoresist layer 55 can be more easily peeled in the step of peeling the photoresist layer 55 described later. In particular, the temperature of the semiconductor substrate 18 (wafer stage: planar electrode 48) is 30 ° C. to 80 ° C. from the viewpoint of maintaining the rectangularity of the etched portion and suppressing the reattachment of the etching product to the sidewall of the photoresist layer. It is more preferable, and it is especially preferable that it is 40 to 60 degreeC.

[Other conditions]
The conditions of the dry etching process vary depending on the material and layer thickness of the color filter layer to be processed, but preferable conditions other than the above conditions will be described below.
(1) The gas flow rate of the mixed gas in the present invention is preferably 1500 mL / min (0 ° C., 1013 hPa) or less, and more preferably 500 to 1000 mL / min (0 ° C., 1013 hPa).
(2) The frequency of the high-frequency voltage can be selected from 400 kHz, 60 MHz, 13.56 MHz, 2.45 GHz, etc., and can be processed with an RF power of 50 to 2000 W, preferably 100 to 1000 W.
(3) Regarding the relationship between source power (RF) and bias, RF power / antenna bias / substrate bias (wafer bias) is preferably 600 to 1000 W / 300 to 500 W / 150 to 250 W, respectively, more preferably It is 700-900W / 350-450 / 200W.

  In the dry etching process, the so-called over-etching process for continuing the dry etching process is performed in order to reliably remove the color filter layer 28B and the transparent film 29 in the region where the R color filter layer 13R is to be formed. May be.

  The overetching treatment is preferably performed by setting an overetching time. The overetching time can be arbitrarily set, but the color filter layer 28B and the transparent film 29 in the region where the R color filter layer 13R is to be formed are used in terms of the etching resistance of the photoresist layer 55 and the rectangularity of the pattern to be etched. It is preferable that it is 30% or less of the total processing time (t1 + t2) of the etching processing time t1 required to remove both and the etching processing time t2 required to remove only the color filter layer 28B. It is more preferably 25%, and particularly preferably 15 to 20%.

  As shown in FIG. 7D, when the dry etching process performed under the above-described conditions is performed, the color filter layer 28B and the transparent film 29 other than the region where the B color filter layer 13B is formed are all removed. Is done. Thereby, the B color filter layer 13B and the transparent film 14 are formed. A region 18 a for forming the R color filter layer 13 </ b> R is formed on the semiconductor substrate 18.

  When the dry etching process is completed, the photoresist layer 55 is stripped using a solvent or a photoresist stripping solution, and the photoresist layer 55 remaining on the transparent film 14 is removed. Thereafter, a dehydration bake treatment may be performed as the solvent removal and dehydration treatment.

  The stripping process of the photoresist layer 55 is performed by, for example, applying a stripping solution or a solvent on the photoresist layer 55 so that the photoresist layer 55 can be removed, and cleaning the photoresist layer 55 with cleaning water. And removal processing. As the former process, for example, a peeling solution or a solvent may be applied on the photoresist layer 55, and paddle development may be performed for a predetermined time. Although there is no restriction | limiting in particular as time to make stripping solution or a solvent stagnant, It is preferable that it is several dozen seconds to several minutes. As the latter treatment, for example, a step of removing the photoresist layer 55 by spraying cleaning water onto the photoresist layer 55 from a spray-type or shower-type spray nozzle can be cited. In addition, the following are used as the stripping solution.

  The stripping solution generally contains an organic solvent, but may further contain an inorganic solvent. Examples of the organic solvent include (1) hydrocarbon compounds, (2) halogenated hydrocarbon compounds, (3) alcohol compounds, (4) ether or acetal compounds, (5) ketones or aldehyde compounds, (6) ester compounds, (7) polyhydric alcohol compounds, (8) carboxylic acids or acid anhydride compounds, (9) phenol compounds, (10) nitrogen compounds, (11) sulfur compounds, (12) Fluorine-containing compounds are exemplified. The stripping solution preferably contains a nitrogen-containing compound, and more preferably contains an acyclic nitrogen-containing compound and a cyclic nitrogen-containing compound.

The acyclic nitrogen-containing compound is preferably an acyclic nitrogen-containing compound having a hydroxyl group. Specific examples include monoisopropanolamine, diisopropanolamine, triisopropanolamine, N-ethylethanolamine, N, N-dibutylethanolamine, N-butylethanolamine, monoethanolamine, diethanolamine, triethanolamine and the like. Preferably, they are monoethanolamine, diethanolamine, and triethanolamine, and more preferably monoethanolamine (H ₂ NCH ₂ CH ₂ OH).

  Examples of cyclic nitrogen-containing compounds include isoquinoline, imidazole, N-ethylmorpholine, ε-caprolactam, quinoline, 1,3-dimethyl-2-imidazolidinone, α-picoline, β-picoline, γ-picoline, 2-pipecoline, 3-pipecoline, 4-pipecoline, piperazine, piperidine, pyrazine, pyridine, pyrrolidine, N-methyl-2-pyrrolidone, N-phenylmorpholine, 2,4-lutidine, 2,6-lutidine and the like are preferable, N-methyl-2-pyrrolidone and N-ethylmorpholine are preferable, and N-methyl-2-pyrrolidone (NMP) is more preferable.

  Thus, the B color filter layer forming step 21 is completed. As shown in FIG. 8, a B color filter layer 13B is formed on a semiconductor substrate 18, and a transparent film 14 is formed on the upper surface thereof. Further, a region 18 a for forming the R color filter layer 13 </ b> R and the like is formed on the surface of the semiconductor substrate 18.

[R color filter layer forming step]
When the B color filter layer forming step 21 is completed, the R color filter layer forming step 22 is started. As shown in FIG. 9, in the coating and drying step 30, the color filter material of the R color filter layer 13R is applied on the semiconductor substrate 18 on which the B color filter layer 13B and the transparent film 14 are formed using a spin coater. After that, heat treatment is performed with a hot plate or the like. Thereby, the color filter layer 28 </ b> R is formed so as to cover the entire surface (including the region 18 a) of the semiconductor substrate 18.

  As shown in FIG. 10, after the color filter layer 28R is formed, a flat layer 58 is formed thereon. The flat layer 58 is formed so that the surface thereof is flat. This is because the entire surface of the color filter layer 28R is uniformly etched during the etch-back process. Therefore, if the surface of the color filter layer 28R is uneven, this uneven shape is formed on the surface of the R color filter layer 13R. This is to prevent transfer. As the flat layer 58, it is preferable to use CT-2000 (manufactured by FUJIFILM Electronics Materials). The thickness of the flat layer 58 is 0.1 μm to 0.5 μm, more preferably 0.2 to 0.4 μm, from the viewpoint of improving the flatness of the surface.

  In the etch-back step 31, an etch-back process (entire anisotropic etching) is performed with the surface of the flat layer 58 as an etch-back start surface using the dry etching apparatus 41 (see FIG. 4). As the dry etching apparatus 41, for example, RIE-ECR: U-621 (manufactured by Hitachi High-Technologies Corporation) is used. The etch-back process (flattening process) is performed until the transparent film that is the end point is reached (until the transparent film 14 is exposed).

[Mixed gas]
The etch-back process is performed using a mixed gas (plasma gas) in which at least oxygen gas, nitrogen gas, and fluorine-based gas are mixed. The fluorine gas is preferably contained in an amount of 1% or more and 10% or less, and more preferably 3% or more and 6% or less with respect to the total flow rate of oxygen gas and nitrogen gas. By suppressing the flow rate of the fluorine-based gas within the above range, the etching surface can be suppressed.

[Internal pressure of chamber]
The internal pressure of the chamber 42 is preferably 1.0 to 5.0 Pa, and more preferably 2.0 to 4.0 Pa. By performing the etch-back process under the conditions that satisfy the mixing ratio of the mixed gas and the internal pressure of the chamber 42, the R color filter layer 13R can be formed without damaging the flatness of the surface of the R color filter layer 13R. The uniformity of the film thickness can be maintained.

[Other conditions]
The frequency of the high-frequency voltage applied to the planar electrode 48 and the counter electrode 49 can be selected from 400 kHz, 60 MHz, 13.56 MHz, 2.45 GHz, and the like, for example, with an RF power of 50 to 2000 W, preferably 100 to 1000 W. It can be processed with RF power. Moreover, as a relationship between the source power (RF) and the bias at the time of the etch back process, it is preferable that the RF power / antenna bias / substrate bias is 400 to 800 W / 50 to 200 W / 100 to 300 W, respectively, more preferably. It is 500-700W / 100-150W / 200-300W.

  Further, as the conditions other than those described above (for example, the temperature of the semiconductor substrate), the conditions described in the above dry etching process can be suitably applied.

The diagnostic monitor 46 (see FIG. 4) is a reaction product produced by etching back the transparent film 14, specifically, the luminescent species SiF (SiO ₂ Si ions and plasma gas fluorine ions are combined. Change in plasma emission intensity (wavelength 440 nm). That is, the plasma emission intensity of SiF is 0 V until the transparent film 14 is exposed after the etch back process is started. Then, when the transparent film 14 is exposed by the etch-back process, and when the transparent film 14 is further etched-back, SiF is generated and the plasma emission intensity of SiF increases. For this reason, by detecting the change in the plasma emission intensity of SiF, it is possible to determine whether or not the transparent film 14 is exposed, that is, whether or not the etch-back process has reached the end point.

Further, when measuring the plasma emission intensity (emission spectrum intensity), from the viewpoint of reproducibility and sensitivity, in addition to SiF, the plasma emission intensity of each emission species such as CO, CN, Si, SiF ₂ , SiO, TiF, etc. These changes may be measured simultaneously. For example, in this embodiment, as shown in FIG. 12, the plasma emission intensities of SiF and TiF (other than SiF and TiF will be described in the examples) were measured. Until about 20 seconds elapse after the etch back process is started (0 seconds), the plasma emission intensity of SiF and TiF is 0 V, so the transparent film 14 is not exposed (the etch back process reaches the end point). Not)). Then, after 20 seconds, the plasma emission intensity of the luminescent species SiF and TiF increases rapidly, so that it can be seen that the etch-back process of the transparent film 14 has started (the transparent film 14 has been exposed). It is determined that the back process has reached the end point.

  If it is determined that the etch back process has reached the end point, the etch back process is stopped. The determination of whether or not the etch-back process has ended and the stop of the etch-back process are based on the exposure signal (SiF, TiF emission detection signal) output from the diagnostic monitor 46, and the control unit 47 (see FIG. 4). Do. The etch back processing time is preferably within 10 minutes, more preferably within 7 minutes.

  Further, after determining that the etch-back process has reached the end point, an over-etch process in which the etch-back process is continued for a predetermined time may be performed. This over-etching treatment is preferably performed by setting an over-etching time within a range where the transparent film 16 remains. The over-etching time can be arbitrarily set, but is preferably 30% or less of the total etch-back processing time in terms of maintaining the surface flatness of the R color filter layer 13R and the uniformity of the film thickness. More preferably, it is -25%, and it is especially preferable that it is 15-20%.

  As shown in FIG. 13, when the transparent film 14 is exposed by the etch-back process described above, the surface of the color filter layer 28R and the surface of the previously formed B color filter layer 13B (transparent film 14) are substantially planes. The R color filter layer 13 </ b> R is formed on the semiconductor substrate 18. The R color filter layer 13R is also formed in a region where the G color filter layer 13G is formed. The R color filter layer forming step 22 is thus completed.

[G color filter forming process]
When the R color filter layer forming step 22 is completed, the G color filter layer forming step 23 is subsequently started. As shown in FIG. 14A, in the patterning step 33, a photoresist layer 55 is formed on the transparent film 29 and the R color filter layer 13R by the same method as the patterning step 27 (see FIG. 7). Thereafter, the region of the photoresist layer 55 where the G color filter layer 13G is to be formed is irradiated with i-line through a mask 56a and the like to perform exposure processing.

  As shown in (B), when the exposure process is completed, a development process or the like is performed in the same manner as the patterning step 27 described above. Thereby, an opening 55b is formed in the region of the photoresist layer 55 where the G color filter layer 13G is to be formed. Next, similarly to the patterning step 27, a dry etching process, a peeling process of the photoresist layer 55, and the like are performed. As a result, as shown in (C), the R color filter layer 13R exposed from the opening 55b of the photoresist layer 55, that is, the R color filter layer 13R formed in the region 18b where the G color filter layer 13G is formed, is removed. The

  As shown in FIG. 15, when the patterning step 33 is completed, the coating and drying step 34 is started. In the coating / drying step 34, the entire surface of the semiconductor substrate 18 (including the R color filter layer 13 </ b> R, the transparent film 14, and the region 18 b) is covered by the same method as the coating / drying step 30 (see FIG. 9). A color filter layer 28G is formed. Next, the above-described flat layer 58 is formed on the color filter layer 28G.

  As shown in FIG. 16A, when the flat layer 58 is formed, the etch-back process 35 is started. In the etch-back process 35, the etch-back process (flattening process) of the color filter layer 28G and the flat layer 58 is started under the same conditions as the etch-back process 31 described above. As described above, the etch-back process determines that the etch-back process has reached the end point (the transparent film 14 is exposed) when the plasma emission intensity of the luminescent species SiF and TiF increases rapidly as measured by the diagnostic monitor 46. .

  As shown in (B), when the etch back process reaches the end point, the surface of the color filter layer 28G and the surface of the previously formed B color filter layer 13B (transparent film 14) become substantially flush. The G color filter layer 13G is formed on the semiconductor substrate 18. Thus, the G color filter layer forming step 23 is completed.

  As described above, the color filter layer forming steps 21, 22, and 23 are sequentially performed, and the color filter layer forming step 23 is completed, so that the color filter layers 13B, 13B, and 13G are two-dimensional. The arranged color filter array 13 is formed.

  In the color filter array forming step 20 of the present invention, the transparent film 14 is formed on the B color filter layer 13B formed in the first color, and the formed transparent film 14 is formed into an R color and G color filter layer forming step. By using it for the end point detection of the etch back process performed in 22 and 23, the end point of the etch back process (flattening process) can be easily specified. Accordingly, when forming the R and G color filter layers 13R and 13B for the second and subsequent colors, excessive shaving or remaining film (a color filter layer of another color remains on the previously formed color filter). Is prevented from occurring. Moreover, the film thickness of each color filter layer 13B, 13R, 13G can be made uniform. As a result, the color filter array 13 having excellent optical characteristics can be obtained.

  Further, since the transparent film 14 is transparent to light in the visible region, the above-described effects can be obtained without affecting the optical characteristics of the B color filter layer 13B.

Further, by using silicon oxide (SiO ₂ ) as the main component of the transparent film 14, whether or not the etch-back process has reached the end point based on the presence or absence of detection of the SiF plasma emission in which the change in emission intensity is most noticeable. Can be determined. That is, the determination can be performed accurately.

  In addition, by using the sol-gel method as a method for forming the transparent film 14, the transparent film 14 can be formed using various coating apparatuses such as a spin coater similarly to the color filter layers 28B, 28R, and 28G. Therefore, unlike the case where the transparent film 14 is formed by an apparatus other than a coating apparatus such as a CVD apparatus, for example, the production facilities for the color filter layers 28B, 28R, 28G and the transparent film 29 can be integrated in one place. Thereby, production efficiency can be improved. Further, as described above, a part of the precursor polymer used in the sol-gel method generates OH groups by hydrolysis, so that the hydrophilicity is increased. As a result, the adhesion between the transparent film 14 and the B color filter layer 13B is increased. Sexuality can be increased.

  In the above embodiment, the case where the color filter layers 28R and 28G are planarized using the dry etching apparatus 41 (etch back method) has been described as an example. However, the present invention is not limited to this. It is not something. For example, as shown in FIG. 17, the color filter layers 28R and 28G may be planarized using a CMP apparatus 60 (CMP method) until the transparent film 14 is exposed. When the planarization process is performed using the CMP method, the above-described flat layer 58 (see FIGS. 10 and 15) may not be formed.

  The CMP apparatus 60 is roughly composed of a turntable 61, a polishing pad (polishing cloth) 62, a top ring 63, a retainer ring 64, and a slurry supply unit 65. The turntable 61 is formed in a substantially disk shape. A rotation shaft 66 is provided on the lower surface of the turntable 61. When the rotating shaft 66 is rotated by a shaft rotating mechanism (not shown), the turntable 61 rotates around the rotating shaft 66. A polishing pad 62 is provided on the upper surface of the turntable 61.

  The top ring 63 is provided above the polishing pad 62 and has a substantially reverse concave shape in cross section. The top ring 63 has an airbag 67 on its lower surface side, and holds the semiconductor substrate 18 with the surface thereof (the surface on which the color filter array 13 is formed) facing downward, with the airbag 67 interposed therebetween. The surface of the semiconductor substrate 18 is pressed against the polishing pad 62 by applying a pressure [1.4 kP to 34.5 kP (0.2 to 5.0 psi)] from the back surface side by the airbag 67. A rotation shaft 68 is provided on the upper surface of the top ring 63. When the rotation shaft 68 is rotated by a shaft rotation mechanism (not shown), the top ring 63 rotates about the rotation shaft 68.

  The retainer ring 64 is attached to the substantially annular lower end of the top ring 63 and is used for preventing the semiconductor substrate 18 from falling off. The retainer ring pressure at which the retainer ring 64 presses the polishing pad 62 is adjusted to be 6.9 to 17.2 kP (1.0 to 2.5 psi). The slurry supply unit 65 supplies a slurry in which silica particles are dispersed (slurry flow rate: 100 to 250 ml / min) onto the polishing pad 62.

  While the slurry is supplied from the slurry supply unit 65 onto the polishing pad 62, the turntable 61 and the top ring 63 are rotated in the same direction and at the same rotation speed per hour, so that the surface of the semiconductor substrate 18 [ The color filter layer 28R (see FIG. 11) and the color filter layer 28G (see FIG. 16A)] are planarized (chemical mechanical polishing). This flattening process is performed until the transparent film 14 is exposed, similarly to the above-described etch-back processes 31 and 35. The polishing rate ratio between the transparent film 14 and the color filter layers 28R and 28G is preferably 2 (transparent film 14 / color filter layers 28R and 28G) or more from the viewpoint of end point determination.

  Whether the CMP process has reached the end point can be determined by various methods. For example, an optical sensor is embedded in the turntable 61 and the polishing pad 62. The optical sensor is embedded at a position where it passes under the semiconductor substrate 18 once while the turntable 61 rotates once. Then, light is irradiated from the optical sensor to the polishing surface (surface on which the color filter array 13 is formed) of the semiconductor substrate 18 and the reflected light is observed. When the transparent film 14 is exposed, light having a specific frequency is absorbed. By detecting this, it can be determined whether or not the transparent film 14 is exposed, that is, whether or not the CMP process has reached the end point.

  Alternatively, whether or not the CMP process has reached the end point may be determined based on whether or not a predetermined polishing time has elapsed since the planarization process was started. Specifically, the polishing amount of the color filter layers 28R and 28G per unit time by the CMP apparatus 60 is obtained in advance. The film thickness of each color filter layer 28R, 28G on the transparent film 14 is generally constant. Therefore, based on the polishing amount per unit time of the CMP apparatus 60 and the film thicknesses of the color filter layers 28R and 28G on the transparent film 14, the planarization process is started until the transparent film 14 is exposed. Required polishing time is required. Therefore, in this embodiment, a time obtained by adding the overpolishing time of 20% of the required polishing time to the obtained required polishing time is set as the polishing time. Then, it is determined whether or not the transparent film 14 is exposed based on whether or not the set polishing time has elapsed since the planarization process was started. The method for determining whether the CMP process has reached the end point is not limited to these, and various known determination methods may be used.

  As described above, even when the color filter layers 28R and 28G are planarized using the CMP apparatus 60 (CMP method) until the transparent film 14 is exposed, the transparent film 14 is used for detecting the polishing stopper layer, that is, the end point. Thus, the end point of the etch-back process (planarization process) can be easily specified. Thereby, the effect similar to the effect demonstrated by the said embodiment is acquired.

  The color filter array forming step 20 of the above embodiment is performed in the order of the B color filter layer forming step 21, the R color filter layer forming step 22, and the G color filter layer forming step 23. It is not limited to this, The order of these steps may be changed as appropriate.

  In the above embodiment, the color filter array used in the solid-state imaging device 10 has been described as an example. However, the present invention is not limited to this, and for example, a color filter used in a liquid crystal monitor (LCD). The present invention can also be applied to a filter array and a manufacturing method thereof. In this case, a glass substrate is used instead of the semiconductor substrate 18 described above.

  In the above embodiment, the description has been given by taking etch back (entire anisotropic dry etching) or CMP as an example of the planarization method of the color filter layers 28R and 28G, but the present invention is not limited to this. Instead, various planarization methods may be used.

[Composition of color filter layer]
The colorant that can be used in the present invention is not particularly limited, and various conventionally known dyes and pigments can be used alone or in combination.

[Pigment]
Examples of the pigment that can be used in the present invention 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.

Also. Examples of pigments that can be preferably used in the present invention include the following. It is preferable to select an inorganic pigment having high light resistance. In the following, C.I. 15: 3 is a representative example.
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 Black 1

[dye]
In the present invention, when the colorant is a dye, it can be uniformly dissolved in the composition to obtain a non-photosensitive thermosetting colored resin composition.

  Moreover, there is no restriction | limiting in particular in the dye which can be used as a coloring agent which comprises the composition in this invention, A well-known dye can be used for conventional 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.

[Colorant concentration]
The colorant content in the total solid content of the colored thermosetting composition in the present invention is not particularly limited, but is preferably 50% by mass or more and less than 100% by mass, and 55% by mass or more and 90% by mass or less. Is more preferable. When the content is 50% by mass or more, an appropriate chromaticity as a color filter can be obtained. Moreover, photocuring 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 that can be used in the present invention 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 said thermosetting compound, what has at least 1 group chosen from an epoxy group, a methylol group, an alkoxymethyl group, and an acyloxymethyl group, for example 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. 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.

  Although the total content of the thermosetting compound in the colored 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. 0.2-40 mass% is more preferable, and 1-35 mass% is especially preferable.

[Dispersant]
Moreover, the said dispersing agent can be added in order to improve the dispersibility of a pigment. As the dispersant, known ones can be appropriately selected and used, and examples thereof include a cationic surfactant, a fluorine surfactant, 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 Industry Co., Ltd.), (meth) acrylic acid (co) polymer polyflow No. 75, No. 90, No. 95 (manufactured by Kyoeisha Chemical Co., Ltd.), W001 (manufactured by Yusho Co., Ltd.), etc. Cationic surfactants of: polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl ether, polyethylene glycol dilaurate, polyethylene glycol distearate, sorbitan Fat Nonionic surfactants such as acid esters; Anionic surfactants such as W004, W005, W017 (manufactured by Yusho Co., Ltd.); EFKA-46, EFKA-47, EFKA-47EA, EFKA polymer 100, EFKA polymer 400 , EFKA polymer 401, EFKA polymer 450 (manufactured by Morishita Sangyo Co., Ltd.), disperse aid 6, disperse aid 8, disperse aid 15, disperse aid 9100 (manufactured by San Nopco) Various Solsperse dispersants (manufactured by Nippon Lubrizol Corporation) such as Solsperse 3000, 5000, 9000, 12000, 13240, 13940, 17000, 24000, 26000, 28000; Adeka Pluronic L31, F38, L42, L44, L61, L64, F68 L72, P95, F77, P84, F87, P94, L101, P103, F108, L121, P-123 (manufactured by Asahi Denka Co.) and Isonetto S-20 (manufactured by Sanyo Chemical Co.) and the like.

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

[Various additives]
In the colored thermosetting composition of the present invention, various additives such as a binder, a curing agent, a curing catalyst, a solvent, a filler, and a high amount other than those described above may be used as long as the effects of the present invention are not impaired. Molecular compounds, surfactants, adhesion promoters, antioxidants, ultraviolet absorbers, aggregation inhibitors, dispersants, and the like can be blended.

[binder]
The binder is often added at the time of preparing the pigment dispersion, and does not need 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 composed of 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 benzyl methacrylate / 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 state during spin coating and slit coating.

[Curing agent]
In this invention, when using an epoxy resin as a thermosetting compound, it is preferable to add a hardening | curing agent. 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 above 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 in the present invention, curing by reaction between epoxy groups is effective in addition to curing by reaction with the curing agent. For this reason, a curing catalyst can be used without using a curing agent. The amount of the curing catalyst added is about 1/10 to 1/1000, preferably about 1/20 to 1/500, more preferably 1/30, based on the mass of the epoxy resin having an epoxy equivalent of about 150 to 200. It can be cured with a slight amount of about 1/250.

[solvent]
The colored thermosetting composition in the present invention can be used as a solution dissolved in various solvents. Each solvent used in the colored thermosetting composition in the present invention is basically not particularly limited as long as the solubility of each component and the coating property of the colored thermosetting composition are satisfied.

Examples of the present invention and comparative examples will be shown below to specifically describe the present invention. However, the present invention is not limited to these examples and comparative examples. As an example, a color filter array “first example” having a transparent film 14 mainly composed of silicon oxide (SiO ₂ ) and a color filter having a transparent film 14 mainly composed of titanium oxide (TiO ₂ ). Two examples of the array “second embodiment” were prepared.

Further, as a comparative example, a color filter array “Comparative Example 1” formed by performing an etch-back process or the like without forming the transparent film 14 and a color filter formed by providing another film instead of the transparent film 14 Four examples of arrays “Comparative Example 2” to “Comparative Example 4” were prepared. In Comparative Example 2, an organic film was provided instead of the transparent film 14. In Comparative Example 3, an SiO ₂ film formed by the CVD method was provided instead of the transparent film 14. In Comparative Example 4, a Ta ₂ O ₅ film formed by the CVD method was provided instead of the transparent film 14.

  In each example and comparative example, evaluation was performed by forming only the B color filter layer 13B and the R color filter layer 13R.

[Example 1]
The color filter array of Example 1 was formed by the following procedures (1) to (8).
(1) The color filter layer 28B was formed on the entire surface of the semiconductor substrate 18 with a film thickness of 0.4 μm. The composition (blue pigment / dispersant / resin / monomer / surfactant) of the pigment-containing thermosetting composition (BLUE) used for the color filter material of the color filter layer 28B is 55.25 / 17.35 / It adjusted to 26.07 / 0.83 / 0.5W%.
(2) On the color filter layer 28B, a precursor polymer (VR1 product: Lhasa Industrial Co., Ltd.) containing silicon oxide (SiO ₂ ) is spin-coated, followed by post-baking at 200 ° C. for 5 minutes to form a transparent film 29 Was formed on the color filter layer 28B.
(3) After the photoresist layer 39 was formed on the transparent film 29, i-line exposure, development processing, and the like were performed to form an opening 55a (see FIG. 7B) in the photoresist layer 55.
(4) The color filter layer 28B and the transparent film 29 exposed from the opening 55a were removed under a desired etching condition using a dry etching method to form a B color filter layer 13B. A region 18 a for forming the R color filter layer 13 </ b> R was formed on the semiconductor substrate 18. The etching conditions are as follows: (a) the processing time is 90 seconds, (b) the mixing ratio (CF ₄ / O ₂ / Ar) of the mixed gas (plasma gas) used for etching is 200/50/500 [ml / min], ( c) Source / upper bias / lower bias of high-frequency voltage applied to the planar electrode 48 and the counter electrode 49 are 800 W / 400 W / 200 W, (d) chamber pressure is 4 Pa, and processing temperature (temperature of the semiconductor substrate 18) is 50 ° C. Adjusted.
(5) The remaining photoresist layer 55 is stripped with a stripping solution. As the stripping solution, MS230C (manufactured by Fuji Film Electronics Materials) was used. After performing paddle processing (processing with a small amount of processing solution left on the photoresist layer 55) for 120 seconds, DIW (ultra pure water) was used. ) And a rinsing treatment for 60 seconds and a dehydration baking treatment at a temperature of 120 ° C. for 60 seconds.
(6) The color filter layer 28 </ b> R was formed on the entire surface of the semiconductor substrate 18 including the B color filter layer 13 </ b> B and the transparent film 14. The composition of the pigment-containing thermosetting composition (RED) used for the color filter material of the color filter layer 28R (blue pigment / dispersant / resin / monomer / surfactant) is 55.00 / 17.60 / It adjusted to 26.07 / 0.83 / 0.5W%.
(7) The entire surface of the color filter layer 28R (which may be provided with the flattening layer 39, the same applies hereinafter) is etched back, and when the above-described diagnostic monitor 46 confirms the plasma emission of SiF, the etch back processing ends. Thus, the formation of the R color filter layer 13R was completed. The etch-back process conditions are as follows: (a) the processing time is 40 seconds, (b) the mixture ratio (O ₂ / O ₂ / Ar / CF ₄ ) of the mixed gas used for the etch-back process is 500/25/500/25 [ml. / Min], (c) Source / upper bias / lower bias of high frequency voltage applied to the planar electrode 48 and the counter electrode 49, 600W / 100W / 500W, (d) chamber pressure is adjusted to 2 Pa, processing temperature is adjusted to 50 ° C. did.

[Example 2]
In place of the transparent film 29 made of silicon oxide (SiO ₂ ) in Example 1, a metal alkoxide solution of titanium oxide (TiO ₂ ) (manufactured by Kojundo Chemical Laboratory Co., Ltd .: trade name SYM-Ti5) was formed, and The conditions were the same as those in Example 1 except that the end point of the etch-back process was determined when the emission intensity of TiF was confirmed by the end-point detection of the etch-back process.

[Comparative Example 1]
Example 1 (2) is omitted, the etch back process is performed based on the etch back process time calculated by the following method, instead of forming the transparent film 29, and instead of detecting the end point by the transparent film 29 in the etch back process. The conditions were the same as in Example 1 except for the end. In the etch back process, the etch back process time is calculated based on the remaining film thickness of the color filter layer 28R on the B color filter layer 13B, and the time when the etch back process time has elapsed since the start of the etch back process is calculated. The end point of the etch back process was taken as the end point.

[Comparative Example 2]
In place of the transparent film 29 made of silicon oxide (SiO ₂ ) of Example 1, the organic film layer (CT2000L: manufactured by FUJIFILM Electromaterials) was formed, and the emission intensity of CO by detecting the end point of the etch-back process The conditions were the same as in Example 1 except that the time point at which this was confirmed was the end point of the etch-back process.

[Comparative Example 3]
The conditions were the same as in Example 1 except that a CVD method SiO ₂ thin film was formed instead of the transparent film 29 made of silicon oxide (SiO ₂ ) in Example 1. The CVD SiO ₂ thin film was formed with a plasma CVD apparatus (manufactured by Samco: PD-270STL).

[Comparative Example 4]
Etch back treatment in which the Ta ₂ O ₅ thin film was used in place of the transparent film 29 made of silicon oxide (SiO ₂ ) in Example 1 and when the TaF emission intensity was confirmed by detecting the end point of the etch back treatment. The same conditions as in Example 1 were used except that the end point of was set. The Ta ₂ O ₅ thin film was formed by a high-frequency sputtering apparatus (RFS-200 manufactured by ULVAC).

  Examples 1 and 2 and Comparative Examples 1 to 4 formed as described above are classified into “ease of end point detection”, “film thickness uniformity”, “throughput”, “spectral characteristics”, and “adhesion”. Evaluation was made on a total of five items (see Table 1 below).

“Ease of end point detection” is shown in FIG. 12, in the etch-back process, the transparent film (SiO ₂ ), transparent film (TiO ₂ ), organic film layer, CVD method SiO _{2 of} each example and comparative example. When etching reached a thin film and a Ta ₂ O ₅ thin film (hereinafter referred to as a transparent film, etc.), the determination was made based on the intensity of the specific emission wavelength of the reaction product produced by etching each film. When the emission intensity is 9500 (cps: count per second) or more, “◯: good”, and when the emission intensity is 4000 (cps) to less than 9500 (cps), “Δ: slightly good”, 4000 (cps). ), It was judged as “x: bad”. The SiF of Example 1 has a high emission intensity of 15000 (cps) and can easily detect the end point. Further, the TiF (produced by combining the Si ions of TiO ₂ and the fluorine ions of the plasma gas) of Example 2 also has a lower emission intensity than SiF, but the emission intensity is 9000 (cps) compared to other types. The end point is easy to detect. On the other hand, the organic film layer and the Ta ₂ O ₅ thin film of Comparative Example 3 and Comparative Example 4 have low emission intensity and are not easily detected.

  For “uniformity of film thickness”, the film thickness distribution of the color filter array (two colors) on the 6-inch size semiconductor substrate 18 was obtained after the planarization process. The film thickness distribution was calculated from an average value obtained by measuring the film thickness of the color filter array at each point on the semiconductor substrate 18 using a film thickness meter Filmmetrics F20 (manufactured by Filmetrics Co., Ltd.). When the film thickness distribution is within 5%, “◯: good”, when the film thickness distribution is ± 5%, “△: slightly good”, and when the film thickness distribution is larger than 10%, “×: bad”. Was determined. In Examples 1 and 2, the film thickness of the color filter array was uniform, whereas in Comparative Examples 1 and 2, the film thickness was non-uniform.

  “Throughput” was evaluated by the processing time of the formation process of the transparent film or the like. When the processing time is within 7 minutes, “◯: good” is determined, when the processing time is within 10 minutes, “△: slightly good”, and when the processing time exceeds 10 minutes, “×: bad” is determined. . In Examples 1 and 2, the throughput (processing time) was shortened, while in Comparative Examples 3 and 4, the throughput was long.

  In the “spectral characteristics”, the spectral characteristics of the color filter layer after the flattening process (etch back process) were evaluated using a Hitachi spectrophotometer U-4100). If the spectral characteristics obtained by the measurement match the desired spectral characteristics at 1% or less, “◯: good”, and if they match at 3% or less, “Δ: slightly good”, 5% When it changed over, it was judged as “x: bad”. In Example 1, desired spectral characteristics were obtained. In Example 2, the degree of coincidence with the desired spectral characteristic was lower than that in Example 1, but the coincidence was 3% or less. On the other hand, in Comparative Example 4, desired spectral characteristics were not obtained.

  “Adhesion” means whether or not the transparent film or the like is peeled off by the second color (R color) color filter or the solvent contained in the photoresist after the formation of the transparent film or the like, and is transparent in the photoresist peeling process. It was evaluated using a general optical microscope and an electron microscope (SEM: manufactured by Hitachi) whether or not the film was peeled off. Then, when there was no peeling at all, it was judged as “◯: good”, when some peeling occurred, “Δ: somewhat good”, and when almost peeled off, “×: bad”. In Examples 1 and 2, the transparent film or the like did not peel off, whereas in Comparative Examples 3 and 4, the transparent film or the like peeled off.

  “Comprehensive evaluation” is “○: good” when there is no “x” in all the above-mentioned evaluations, “△: good” when all the above-mentioned evaluations are “Δ”, or any of the above-mentioned evaluations. When there was even one x, it was determined that “x: bad”.

  As shown in Table 1, the transparent film 14 is formed on the B color filter layer 13B formed in the first color, and the formed transparent film 14 is formed into the R color and G color filter layer forming steps 22 and 23. Are used to detect the end point of the etch back process performed in each of the etch back processes 31 and 35, so that “ease of end point detection”, “thickness uniformity”, “throughput”, “spectral characteristics”, “adhesion” ”Was confirmed to improve.

It is sectional drawing of the solid-state image sensor of this invention. It is a top view of a color filter array. It is a flowchart of a color filter formation process. It is the schematic of a dry etching apparatus. It is explanatory drawing for demonstrating the application | coating drying process of a B color filter formation process. It is explanatory drawing for demonstrating the transparent film formation process of a B color filter formation process. It is explanatory drawing for demonstrating the patterning process of a B color filter formation process. It is explanatory drawing for demonstrating the state which the B color filter formation process was completed. It is explanatory drawing for demonstrating the application | coating drying process of a R color filter formation process. It is explanatory drawing for demonstrating that the flat film was formed in starting the etch-back process of R color filter formation process. It is explanatory drawing for demonstrating the etch back process of a R color filter formation process. It is explanatory drawing for demonstrating performing the end point detection of an etch back process based on the change of emitted light intensity, such as SiF and TiF. It is explanatory drawing for demonstrating the state which the R color filter formation process was completed. It is explanatory drawing for demonstrating the patterning process of a G color filter formation process. It is explanatory drawing for demonstrating the application | coating drying process (flat film formation) of a G color filter formation process. It is explanatory drawing for demonstrating the etch back process of G color filter formation process. 1 is a schematic view of a CMP (Chemical Mechanical Polishing) apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Solid-state image sensor 13 Color filter array 13B B color filter layer 13R R color filter layer 13G G color filter layer 20 Color filter array formation process 25, 30, 34 Application | coating drying process 26 Transparent film formation process 27, 33 Patterning process 28B, 28R, 28G Color filter layer 31, 35 Etch back process 41 Dry etching device 60 CMP device

Claims (11)

In a method for manufacturing a color filter array in which a plurality of color filter layers are formed for each color and arranged two-dimensionally on the surface of a substrate,
A first step of forming a first color filter layer on the surface of the substrate;
A second step of forming a transparent film including at least one of silicon oxide and metal oxide on the color filter layer of the first color;
A third step of patterning the color filter layer of the first color and the transparent film to form a region for forming a color filter layer of the second color on the surface of the substrate;
A fourth step of forming the color filter layer of the second color so as to cover the surface of the substrate on which a region for forming the color filter layer of the second color is formed;
A method for manufacturing a color filter array, comprising: at least a fifth step of flattening a surface of the color filter layer of the second color until the transparent film is exposed. The flattened Nth (N is a natural number of 2 or more) color filter layer is patterned to form a region for forming a (N + 1) th color filter layer on the surface of the substrate. And a sixth step to
A seventh step of forming the (N + 1) th color filter layer so as to cover the surface of the substrate on which the region for forming the (N + 1) th color filter layer is formed;
The method of manufacturing a color filter array according to claim 1, further comprising an eighth step of planarizing a surface of the (N + 1) th color filter layer until the transparent film is exposed.   3. The method of manufacturing a color filter array according to claim 1, wherein the flattening process is performed by an etch back process or a chemical mechanical polishing process.   The etch-back process is performed using a plasma gas, and the exposure of the transparent film is determined by plasma emission of a reaction product generated by etching the transparent film after the etch-back process is started. 4. The method of manufacturing a color filter array according to claim 3, wherein the method is performed by detecting with a spectroscopic device.   5. The method of manufacturing a color filter array according to claim 1, wherein the patterning is performed using a dry etching method.   6. The transparent film is formed by a sol-gel method using a precursor polymer coating solution containing at least one of silicon oxide and metal oxide. Manufacturing method of color filter array.   7. The method of manufacturing a color filter array according to claim 1, wherein the transparent film has a refractive index substantially equal to that of the first color filter layer.   8. The method of manufacturing a color filter array according to claim 7, wherein the refractive index of the transparent film is 1.4 to 1.8.   9. The method of manufacturing a color filter array according to claim 1, wherein the transparent film has a thickness of 50 nm to 200 nm.   A color filter array manufactured by the method for manufacturing a color filter array according to claim 1.   A solid-state imaging device comprising the color filter array according to claim 10.

Images