JP4984719B2 - Manufacturing method of color solid-state imaging device - Google Patents

Description

The present invention provides a color filter, a planarizing layer, and a green filter, a red filter, and a blue filter corresponding to the photoelectric conversion element using a photolithography method on a semiconductor substrate on which a plurality of photoelectric conversion elements are formed. relates to a method of manufacturing a color solid-state imaging device for producing a microlens, in particular, to pattern exposure by using a transmission rate control exposure mask to form a green filter with a step by performing a developing process, the remaining blue and red The present invention relates to a manufacturing method of a color solid-state imaging device for producing a colored filter and a microlens.

A colored filter such as blue, green, red, etc. is usually produced by using a photolithography method on a glass substrate or a substrate made of a semiconductor substrate on which a plurality of photoelectric conversion elements are formed. 10 (a) to 10 (f).
The color filter shown here is an example of a configuration of a color filter used in a color solid-state imaging device or the like, and is an example in which a black matrix is not provided between individual colored filters.

First, a green photosensitive resin solution in which a green pigment is dispersed in an acrylic photosensitive resin is applied onto a substrate 111 using a spinner or the like to form a green photosensitive resin layer 121 (see FIG. 10A).
Further, pattern exposure is performed using a predetermined exposure mask, and a series of patterning processes such as development and post-baking are performed to form a green filter 121G (see FIG. 10B).

  Next, a blue photosensitive resin solution in which a blue pigment is dispersed in an acrylic photosensitive resin is applied onto the substrate 111 on which the green filter 121G is formed using a spinner or the like, thereby forming a blue photosensitive resin layer 122 ( (Refer FIG.10 (c)).

Next, pattern exposure is performed using a predetermined exposure mask, and a series of patterning processes such as development and post-baking are performed to form a blue filter 122B (see FIG. 10D).
Here, since no black matrix is provided between the individual colored filters, the mask alignment and pattern are overlapped by about 0.5 μm so that there is no gap between the blue filter 121G and the blue filter 122B. Perform exposure.
In such a case, as shown in FIG. 10 (d), a protrusion 131 called a common angle (one) is formed at an overlap portion between the green filter 121G and the blue filter 122B.

  Next, a red photosensitive resin solution in which a red pigment is dispersed in an acrylic photosensitive resin is applied to the substrate 111 on which the green filter 121G and the blue filter 122B are formed using a spinner or the like, and the red photosensitive resin layer 123 is applied. (See FIG. 10E).

Next, pattern exposure is performed using a predetermined exposure mask, and a series of patterning processes such as development and post-baking are performed to form a red filter 123R (see FIG. 10F).
Here, as described above, the protrusion 132 is formed in the overlap portion between the green filter 121G and the blue filter 122B and the red filter 123R.

When the protrusions 131 and 132 are formed between the colored filters, a step of about 0.2 μm is generated.
In a solid-state imaging device, a macro lens is formed on the color filter in order to improve the light collecting property. However, if the surface of the color filter has poor flatness, a desired microlens shape cannot be obtained. is doing.

As a technique for improving the flatness of a color filter for solving the above problems, a color filter configuration using a stepped black matrix has been proposed (for example, see Patent Document 1).
FIG. 9A is a schematic partial cross-sectional view showing a configuration example of a color filter using a stepped black matrix. FIG. 9B is a partially enlarged configuration cross-sectional view of the stepped black matrix. FIGS. 9C and 9D are explanatory views showing an example of the shape of the color filter around the stepped black matrix of the color filter formed using the stepped black matrix.

  In the color filter using the stepped black matrix shown in FIG. 9A, the stepped black matrix 150BL is first formed on the substrate 111, and then the green filter 125G, the blue filter 126B, and the red filter 127R are sequentially formed. It is.

  As shown in FIG. 9B, the stepped black matrix 150BL forms a stepped portion by superimposing the lower layer black matrix 151BL and the upper layer black matrix 152BL having a pattern width narrower than that of the lower layer black matrix 151BL. Yes.

In the case where a colored filter is formed on the substrate 111 on which the stepped black matrix 150BL is formed, the behavior and shape of the color resist around the stepped black matrix 150BL will be described.
First, when, for example, a blue color resist is applied on the substrate 111 on which the stepped black matrix 150BL is formed by a spin coating method or the like, the step around the upper portion of the stepped black matrix 150BL serves as a slope, As shown in FIG. 9C, the color resist flows along the inclination, and no protrusion is generated around the upper portion of the stepped black matrix 150BL.

  Further, in the pattern exposure step, pattern exposure is performed with a pattern slightly smaller than the upper black matrix 151BL of the stepped black matrix 150BL, and patterning processing such as development is performed, as shown in FIG. The blue filter is slightly depressed at the periphery of the 150BL upper black matrix 151BL, and flatness is ensured.

Thus, by forming a color filter using a stepped black matrix, a color filter having excellent flatness can be obtained.
Furthermore, it has been found that a color filter using a stepped black matrix can also be applied to a color filter configuration without a black matrix.
However, in order to obtain the above stepped black matrix 150BL, it is formed in two layers of a lower layer black matrix 151BL and an upper layer black matrix 152BL, so that a stepped black matrix or a step adhesion color filter is formed. However, there is a problem that the man-hour increases by one.
JP-A-6-331815

  The present invention has been devised in view of the above problems, and a colored filter and a microlens corresponding to the photoelectric conversion element are formed on a semiconductor substrate on which a plurality of photoelectric conversion elements are formed using a photolithography method. Color solid-state image pickup device for efficiently producing a colored filter excellent in surface smoothness by forming a step-attached color filter by a single exposure and development process in a manufacturing method of a color solid-state image pickup device to be manufactured It aims at providing the manufacturing method of.

In order to achieve the above object in the present invention, first, in claim 1, a green color corresponding to the photoelectric conversion element using a photolithography method is formed on a semiconductor substrate on which a plurality of photoelectric conversion elements are formed. A color filter and a microlens composed of a filter, a red filter, and a blue filter are formed, and the green filter is a stepped green filter provided with a step in a peripheral portion, and sequentially the remaining coloring filter, microlens, In the method for manufacturing a color solid-state image pickup device for forming a color solid-state image pickup device, the color solid-state image pickup device is manufactured by the following steps in order.
(A) A colored photosensitive layer is formed on a substrate on which a plurality of photoelectric conversion elements are formed, and the colored photosensitive layer is formed using a transmittance control exposure mask composed of a transmission pattern, a light shielding pattern, and a transmittance control pattern. Pattern exposure and performing development processing to form a stepped green filter.
(B) A colored photosensitive layer is formed, and a series of patterning processes in order from pattern exposure and development are performed by pattern exposure using a normal exposure mask composed of a transmission pattern and a light shielding pattern, and the remaining blue or A step of sequentially forming red colored filters in a state where they are overlapped with the step portions of the stepped green filter .
(C) A step of forming a microlens.

Also, the green filter is obtained by a method for manufacturing a color solid-state imaging device according to claim 1, characterized in that it is formed using a negative type colored resist.

  According to the method for manufacturing a color solid-state imaging device of the present invention, the step-attached color filter is manufactured by patterning processing such as pattern exposure and development once, so that the manufacturing process can be shortened and surface flatness and A color filter having excellent adhesion can be produced, and as a result, a color solid-state imaging device having excellent sensitivity characteristics can be obtained.

Hereinafter, embodiments of the present invention will be described.
FIG. 1A is a schematic plan view showing an embodiment of a solid-state image sensor manufactured by the method for manufacturing a color solid-state image sensor of the present invention, and FIG. The schematic structure sectional drawing of the solid-state image sensor cut | disconnected by A 'is shown, respectively.
Since the solid-state imaging device manufactured by the method for manufacturing a color solid-state imaging device according to the present invention manufactures a step-attached color filter to be described later by patterning processing such as pattern exposure and development once, the manufacturing process is shortened. Therefore, a color filter having excellent surface flatness and adhesion can be produced.

Hereinafter, the manufacturing method of the color solid-state image sensor of this invention is demonstrated.
2 (a) to 2 (e) and FIGS. 3 (f) to 3 (h) are partial schematic cross-sectional views showing an embodiment of the method for manufacturing a color solid-state imaging device of the present invention in the order of steps.
First, a transparent resin solution made of an acrylic resin or the like is applied on the semiconductor substrate 11 on which the photoelectric conversion element 12 is formed by spin coating or the like, and heated and cured at a predetermined temperature to form the planarization layer 21 (FIG. 2 (a) and (b)).
As the transparent resin, in addition to the acrylic resin, urea resin such as epoxy, polyester, urethane, melamine, and area, styrene resin, phenol resin, or a copolymer thereof can be used.

Next, a negative type photosensitive resin is coated with a color pigment (for example, CI Pigment Yellow 150, CI Pigment Green 36 and CI Pigment Green 7), an organic solvent such as cyclohexanone or PGMEA, and an acid. A negative green resist prepared by kneading a degradable resin, a photoacid generator, and a dispersant with a roll mill or the like is applied by spin coating or the like to form a green photosensitive layer 31g (see FIG. 2C). .
Here, the reason for using the negative type green resist is that in the checkered pattern (Bayer array) solid-state image sensor, the green filter is formed first, so the resolution of the green filter is the same as that of the color filter of the solid-state image sensor. It is affected by pattern reproducibility and resolution. For this reason, a negative photosensitive resin capable of forming a color filter with good spectral characteristics and high resolution is set.

The negative photosensitive resin is, for example, a combination of a novolak resin and a quinone azide compound, and an alkali-soluble vinyl polymer can be further added to this combination.
In addition, polyvinyl phenol derivatives and acrylics may be used.

  The color material may be an organic pigment or a dye in addition to the above-described pigment.

  Furthermore, a lactic acid ester may be added to the organic solvent.

  The acid-decomposable resin is a resin having a group that can be converted to alkali-soluble (for example, a carboxyl group, a phenolic hydroxyl group, etc.) by contact with an acid.

  A photoacid generator is a compound that generates an acid when irradiated with light, and one or more of such compounds can be used. Examples of the photoacid generator include salts of onium halide ions, BF4 ions, PF6 ions, AsF6 ions, SbF6 ions, CF3SO3 ions, etc., organic halogen compounds, naphthoquinone diazide sulfonic acid compounds, and photosulfonic acid generating compounds. Etc. can be used.

  In addition, when adding an organic pigment as a color material to a negative photosensitive resin, considering the quality in various manufacturing processes when manufacturing a color filter from a negative colored photosensitive layer, the organic in the negative green resist The solid ratio of the pigment is preferably 30 to 50%, particularly preferably around 40%.

  When the solid ratio is lower than 30%, a sufficient coloring effect on the colored photosensitive layer cannot be obtained. On the other hand, if the solid ratio exceeds 50%, it is difficult to accurately process the colored photosensitive layer into a color filter shape, and the residue mainly composed of pigment increases after development.

Next, pattern exposure for producing a stepped green filter is performed using the transmittance control exposure mask 50g shown in FIGS. 4A and 4B (see FIG. 2D).
Here, the transmittance control exposure mask 50g will be described.
4A is a partial schematic plan view of the transmittance control exposure mask 50g, and FIG. 4B is a partial schematic cross section of the transmittance control exposure mask 50g obtained by cutting FIG. 4A along the line AA ′. Each figure is shown.
The transmittance control exposure mask 50g includes a transmission pattern 61, a light shielding pattern 62, and a transmittance control pattern 63. The transmittance control pattern 63 controls the step shape (width and height) of the edge of the green filter. It is something to try.

FIG. 5 shows an example of pattern sizes of the transmission pattern 61, the light shielding pattern 62, and the transmittance control pattern 63 of the transmittance control exposure mask 50g.
A 1.8 μm square transmission pattern 61 and a 2.1 μm square light shielding pattern 62 are set for a cell size of 2.2 μm square, and a transmittance control pattern 63 having a width of 0.2 μm is formed around the transmission pattern 61. This is an example of forming a stepped green filter by arranging a transmittance control pattern 63 having a width of 0.05 μm around the light shielding pattern 62.

An example of the transmittance setting of the transmittance control pattern 63 will be described.
FIG. 6 shows the remaining film rate of the green photosensitive layer 31 g when the green photosensitive layer is subjected to pattern exposure while changing the transmittance of the transmittance control pattern 63.
For example, in order to obtain a green filter having a thickness of 0.8 μm using the green photosensitive layer 31 g having a thickness of 1.4 μm, it is understood that the transmittance control pattern 63 having a transmittance of 20% may be used. Thus, if the transmittance and residual film curve of such an exposure pattern are measured for every green photosensitive layer, the optimal transmittance of the transmittance control pattern can be set in accordance with the residual film thickness.

Next, it develops with an exclusive developing solution, heat-hardens, and forms the stepped green filter 31G in the predetermined position on the smooth layer 21 (refer FIG.2 (e)).
Here, since the negative green photosensitive layer 31g is used, the pattern-exposed portion of the transmission pattern 61 is cured, and the cured portion remains after development, thereby forming a filter cell for forming another colored filter. Is done.
Further, since the pattern is not exposed in the light shielding pattern 62, it is uncured and removed by development.
Further, in the transmittance control pattern 63, a film thickness step corresponding to the transmittance of the transmittance control pattern 63 is formed.

Next, a negative blue resin prepared by kneading a negative photosensitive resin with a blue pigment (for example, CI Pigment Blue 15: 6, CI Pigment Violet 23) and a dispersing agent using a roll mill or the like. A resist is applied by spin coating or the like, a blue photosensitive layer is formed, pattern exposure is performed using an exposure mask 50b in which a light-transmitting region 64 is formed in the light-shielding region 66 shown in FIGS. 7A and 7B, development, etc. A blue filter 31B is formed between the stepped green filters 31G (see FIG. 3F).
Here, the edge portion of the blue filter 31B is formed so as to be overlapped with the step portion of the stepped green filter 31G, so there is no rise in the step portion, and even if the pixel size is around 2 μm, the filter peels off. There is no such thing as causing

  Next, a red pigment (for example, CI Pigment Red 177, CI Pigment Red 48: 1 and CI Pigment Yellow 139) and a dispersing agent, etc., are added to the negative photosensitive resin with a roll mill or the like. A negative-type red resist produced by kneading is applied by spin coating or the like to form a red photosensitive layer, and an exposure mask 50r in which a transmission pattern 65 is formed in the light-shielding region 66 shown in FIGS. 8A and 8B is formed. Using the pattern exposure, a series of patterning processes such as development are performed to form a red filter 31R between the stepped green filters 31G (see FIG. 3G). Here, since the edge part of the red filter 31R is formed in a state of being overlapped with the step part of the stepped green filter 31G, the filter part is peeled off even when the pixel size is around 2 μm without the rise of the step part. There is no such thing as causing

  Next, an acrylic photosensitive resin solution having thermal reflow properties is applied by spin coating, dried and cured to form a photosensitive resin layer having a predetermined thickness, and a series of patterning such as pattern exposure and development using an exposure mask. Processing is performed to form a lens pattern on the green filter 31G, the blue filter 31B, and the red filter 31R, and the lens pattern is heated and reflowed at a predetermined temperature to form a microlens 41 having a predetermined curvature. A solid-state image sensor is obtained (see FIG. 3 (h)).

Regarding the microlens formation technique, as a known technique, in addition to the method using the thermal fluidity (heat flow) of the resin by the above heat flow, a technique for processing a lens by several etching techniques is disclosed. Therefore, it may be properly used.

Hereinafter, the present invention will be described in detail by way of examples.
First, a transparent resin solution made of an acrylic resin or the like is applied to the semiconductor substrate 11 on which the photoelectric conversion element 12 is formed by spin coating or the like, and is heated and cured at 200 ° C. for 9 minutes to flatten a thickness of 0.6 μm. A layer 21 was formed (see FIGS. 2A and 2B).

  Next, a negative type photosensitive resin, a color pigment (CI Pigment Yellow 150, CI Pigment Green 36 and CI Pigment Green 7), an organic solvent such as cyclohexanone and PGMEA, and acid-decomposable A negative green resist prepared by kneading a resin, a photoacid generator, and a dispersant with a roll mill was applied by spin coating or the like, and prebaked at 70 ° C. for 1 minute to form a green photosensitive layer 31 g (see FIG. 2 (c)).

  Next, transmittance control exposure in which a transmission pattern 61, a light shielding pattern 62, and a transmittance control pattern 63 corresponding to a filter size of 2.2 μm shown in FIGS. 4A and 4B are arranged in a checkered pattern (Bayer array). The mask 50g was set on a Nikon-i112 stepper, and pattern exposure for producing a stepped green filter was performed in 700 msec (see FIG. 2D).

  Next, spray development is performed for 60 seconds with a developer composed of an organic alkali aqueous solution, rinsed with pure water, hardened by heat curing at 200 ° C. for 6 minutes on a hot plate, and predetermined on the smooth layer 21. A stepped green filter 31G was formed at the position (see FIG. 2E).

  Next, a negative blue resist prepared by kneading a negative photosensitive resin with a blue pigment (CI Pigment Blue 15: 6, CI Pigment Violet 23), a dispersant and the like using a roll mill or the like. A blue photosensitive layer is formed by spin coating at 1200 rpm, and an exposure mask 50b in which a transmissive pattern 64 is arranged in a light shielding region 66 corresponding to a filter size of 2.2 μm shown in FIGS. 7A and 7B is used. The pattern was exposed to light and a series of patterning processes such as development were performed to form a blue filter 31B (see FIG. 3F).

Since the edge portion of the blue filter 31B is formed in a state of being overlapped with the step portion of the stepped green filter 31G, even if the filter size is 2.2 μm, the filter is not peeled off.
The film thickness difference from the upper part of the blue filter 31B was 0.1 μm or less, and high flatness was obtained.

  Next, a red pigment (CI Pigment Red 177, CI Pigment Red 48: 1 and CI Pigment Yellow 139) and a dispersant are kneaded with a negative photosensitive resin with a roll mill or the like. The negative red resist produced in this way is applied by spin coating or the like to form a red photosensitive layer, and a transmission pattern 65 is arranged in the light shielding region 66 corresponding to the filter size of 2.2 μm shown in FIGS. Pattern exposure was performed using the exposed exposure mask 50r, and a series of patterning processes such as development were performed to form a red filter 31R (see FIG. 3G).

Since the edge portion of the red filter 31R is formed so as to be overlapped with the step portion of the stepped green filter 31G, even if the filter size is 2.2 μm, the filter is not peeled off.
The film thickness difference from the upper part of the red filter 31R was 0.1 μm or less, and high flatness was obtained.

  Next, an acrylic photosensitive resin solution having thermal reflow properties is applied by spin coating, dried and cured to form a photosensitive resin layer having a predetermined thickness, and a series of patterning such as pattern exposure and development using an exposure mask. Processing is performed to form a lens pattern on the green filter 31G, the blue filter 31B, and the red filter 31R, and the lens pattern is heated and reflowed at a predetermined temperature to form a microlens 41 having a predetermined curvature. A solid-state image sensor was obtained (see FIG. 3 (h)).

  As described above, according to the method for manufacturing a color solid-state imaging device of the present invention, the step-attached color filter is manufactured by patterning processing such as pattern exposure and development once, so that the manufacturing process can be shortened. In addition, a color filter excellent in surface flatness and adhesion can be produced, and as a result, a color solid-state imaging device excellent in sensitivity characteristics can be obtained.

(A) is a partial schematic plan view showing an example of a color solid-state imaging device manufactured by the method for manufacturing a color solid-state imaging device of the present invention. (B) is a partial schematic cross-sectional view of a color solid-state imaging device obtained by cutting (a) along the line A-A ′. (F)-(h) is a partial schematic cross section which shows a part of one Example of the manufacturing method of the color solid-state image sensor of this invention to process order. (A)-(e) is a partial schematic cross section which shows a part of one Example of the manufacturing method of the color solid-state image sensor of this invention to process order. (A) is a partial schematic plan view which shows one Example of the pattern arrangement | sequence of the transmittance | permeability control exposure mask 50g. (B) is a partial schematic cross-sectional view of a transmittance control exposure mask 50g obtained by cutting (a) along the line A-A ′. It is explanatory drawing which shows an example of the pattern size of the transmission pattern 61, the light shielding pattern 62, and the transmittance control pattern 63 of the transmittance control exposure mask 50g. It is explanatory drawing which shows an example of the residual film curve which investigated the residual film rate of the green photosensitive layer at the time of pattern exposure changing the transmittance | permeability of the transmittance | permeability control pattern 63 about a green photosensitive layer. (A) is a partial schematic plan view which shows an example of the pattern arrangement | sequence of the exposure mask 50b for blue filter preparation. (B) is a partial schematic cross-sectional view of the exposure mask 50 b obtained by cutting (a) along the line A-A ′. (A) is a partial schematic plan view which shows an example of the pattern arrangement | sequence of the exposure mask 50b for red filter preparation. (B) is a partial schematic cross-sectional view of the exposure mask 50 b obtained by cutting (a) along the line A-A ′. (A) is a typical fragmentary sectional view which shows the structure of the color filter using the black matrix with a level | step difference. (B) is a partial enlarged configuration sectional view of a stepped black matrix. (C) And (d) is explanatory drawing which shows the shape of the color filter of the black matrix with a level | step difference of the color filter formed using the level | step difference black matrix. (A)-(f) is a partial schematic cross section which shows an example of the manufacturing method of a color filter in order of a process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Semiconductor substrate 12 ... Photoelectric conversion element 21 ... Planarization layer 31g ... Green photosensitive layer 31G ... Green filter 31B ... Blue filter 31R ... Red filter 41 ... Micro lens 50g ... Transmission control exposure Mask 50b, 50r ... Exposure mask 51 ... Glass substrate 61, 64, 65 ... Transmission pattern 62 ... Light shielding pattern 63 ... Transmission control pattern 66 ... Light shielding region 111 ... Substrate 121 ... Red photosensitive resin Layers 121R, 125R ... Red filter 122 ... Green photosensitive resin layers 122G, 126G ... Green filter 123 ... Blue photosensitive resin layers 123B, 127B ... Blue filters 131, 132 ... Protrusions 150BL ... Stepped Black matrix 151BL …… Lower layer black matrix 151BL …… Upper layer black matrix

Claims (2)

On a semiconductor substrate on which a plurality of photoelectric conversion elements are formed, a colored filter and a microlens composed of a green filter, a red filter, and a blue filter are formed corresponding to the photoelectric conversion element using a photolithography method. The green filter is a stepped green filter provided with a step in the periphery, and in order to produce a color solid-state image sensor by sequentially forming the remaining colored filters and microlenses, A manufacturing method of a color solid-state imaging device, which is manufactured by the following steps.
(A) A colored photosensitive layer is formed on a substrate on which a plurality of photoelectric conversion elements are formed, and the colored photosensitive layer is formed using a transmittance control exposure mask composed of a transmission pattern, a light shielding pattern, and a transmittance control pattern. Pattern exposure and performing development processing to form a stepped green filter.
(B) A colored photosensitive layer is formed, and a series of patterning processes in order from pattern exposure and development are performed by pattern exposure using a normal exposure mask composed of a transmission pattern and a light shielding pattern, and the remaining blue or A step of sequentially forming red colored filters in a state where they are overlapped with the step portions of the stepped green filter .
(C) A step of forming a microlens.   The method for manufacturing a color solid-state imaging device according to claim 1, wherein the green filter is formed using a negative coloring resist.