JP2003101001A - Solid-state image pickup element and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid-state image pickup element, in which ghosts due to reflected light from a gap between lenses are reduced and image quality is improved without increasing the scattered light of the light which is made incident on the gap between the lenses and noise, such as smears due to oblique light which is made incident on a base part. SOLUTION: In the solid-state image pickup element sequentially provided with an undercoat layer 13 and multiple micro lenses, the microlens has a resin layer 12 which is selectively made thin on a microlens pattern 11 selectively thick on the gap between the microlens patterns and has an infrared ray absorbing function applied, and disposed thereon.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state image pickup device provided with a minute microlens, and more particularly to a solid-state image pickup which improves the image quality by reducing the scattering of light incident on the microlens and ghosts. The present invention relates to an element and a manufacturing method thereof.

[0002]

2. Description of the Related Art A region (opening) in which a light receiving element on a solid-state image pickup device such as a CCD contributes to photoelectric conversion depends on the size and the number of pixels of the solid-state image pickup device.
It will be limited to about 40%. The small opening means
Since it directly leads to a decrease in sensitivity, a microlens for condensing light is generally formed on the light receiving element to compensate for this. However, recently, a high-definition solid-state imaging device with more than 2 million pixels has been strongly demanded,
Micro lens attached to this high-definition solid-state image sensor,
In addition, deterioration of image quality (that is, deterioration of S / N ratio) due to reflected light from the gap between the microlenses has become a serious problem.

As a known technique for forming such a microlens, for example, Japanese Patent Laid-Open No. 60-530 is known.
No. 73 is shown in more detail. This JP-A-6
Japanese Patent Laid-Open No. 0-53073 discloses in detail a technique using heat fluidity (heat flow) of a resin by heat as a technique for forming a lens into a round hemisphere, and a technique for processing a lens by some etching methods. It is disclosed. in addition,
As a measure to improve the loss of light collection performance due to light scattering on the lens surface, polyglycidyl methacrylate (PG
A technique for forming an organic film such as MA) or an inorganic film such as OCD (a coating liquid for forming a SiO 2 film from Tokyo Ohka Kogyo Co., Ltd.) is also disclosed. Further, a technique for effectively condensing light by laminating a thin film having a refractive index different from that of a lens material on a microlens is disclosed in, for example, JP-A-60-53073.
Japanese Patent Laid-Open Publication No. 5-48057 and the like.

The microlens on the solid-state image pickup device is formed for the purpose of collecting light on the light-receiving portion, which is a photoelectric conversion element, so as to collect light on the light-receiving portion to compensate for the decrease in sensitivity. However, the scattered light that enters the inter-lens gap of the microlens and the oblique light that enters the hem of the microlens, which has poor light collection efficiency, increase noise such as smear, resulting in deterioration of the image quality of the input image. Bring Further, when the subject has a high-luminance portion, the inter-lens gap or the reflected light from the microlenses becomes a ghost, which causes white blurring and a decrease in saturation, resulting in a deterioration in the image quality of the input image.

[0005]

SUMMARY OF THE INVENTION The present invention increases the noise such as smear due to scattered light of light incident on the inter-lens gap of the microlens or oblique light incident on the skirt of the microlens, which has poor light collection efficiency. It is an object of the present invention to provide a solid-state imaging device that does not cause the above-mentioned problems and that significantly reduces ghosts and the like due to reflected light from the inter-lens gap and that improves image quality. Another object of the present invention is to provide a method for manufacturing the above solid-state imaging device.

[0006]

According to the present invention, there is provided a solid-state image pickup device comprising a semiconductor substrate having a plurality of photoelectric conversion elements formed thereon, and at least an undercoat layer and a plurality of microlenses in order. In the solid-state image pickup device, a resin layer having an infrared absorbing function is selectively thin and selectively thick, and a resin layer having an infrared absorbing function is selectively provided on the gap between the microlens patterns.

Further, according to the present invention, in the solid-state image pickup device according to the above-mentioned invention, the surface of the resin layer having an infrared absorbing function provided on the gap between the microlens patterns is not smooth. Is.

In the solid-state image pickup device according to the above invention, the resin layer having an infrared absorbing function is
It is a solid-state imaging device characterized by being a resin containing a plurality of infrared absorbers.

Further, the present invention is characterized in that, in the solid-state image pickup device according to the above invention, the plurality of infrared absorbing agents are infrared absorbing agents selected from a plurality of phthalocyanine compounds, diimonium compounds and azo compounds. Is a solid-state image sensor.

The present invention is also the solid-state image pickup device according to the above-mentioned invention, wherein the resin layer having an infrared absorbing function has a refractive index lower than that of the microlens pattern.

Further, according to the present invention, in a method of manufacturing a solid-state image pickup device, which comprises a semiconductor substrate having a plurality of photoelectric conversion elements formed thereon, at least an undercoat layer and a plurality of microlenses in order, the microlenses are A microlens that is selectively thin on the lens pattern and selectively thick on the gap between the microlens patterns and is covered with a resin layer having an infrared absorbing function, wherein the resin layer having an infrared absorbing function is composed of a plurality of infrared rays. It is a resin containing an absorber, and before forming a resin layer having an infrared absorbing function, a recess is formed on the surface of the undercoat layer at the position of the gap between the microlens patterns to cover the resin layer having an infrared absorbing function. A method for manufacturing a solid-state imaging device, which is characterized in that it is provided.

The present invention is also the method of manufacturing a solid-state image sensor according to the above-mentioned invention, wherein the etching rate of the undercoat layer is higher than the etching rate of the microlens pattern. .

In the method for manufacturing a solid-state image pickup device according to the present invention, a plurality of resin layers having an infrared absorbing function on the microlens pattern are contained after the resin layer having the infrared absorbing function is provided. The method for producing a solid-state image pickup device is characterized in that the infrared absorbent of (1) is decolorized to increase the transmittance in the visible region.

In the method for manufacturing a solid-state image pickup device according to the present invention, the resin layer having the infrared absorbing function is disposed, and then the resin layer having the infrared absorbing function on the microlens pattern is removed. A method for manufacturing a solid-state imaging device, characterized in that a resin layer having an infrared absorbing function is left on the gaps between the microlens patterns and on the bottoms of the microlens patterns.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION A solid-state image sensor according to the present invention will be described below based on its embodiments. FIG. 1 is a sectional view showing an embodiment of a solid-state image sensor according to the present invention. As shown in FIG. 1, the solid-state imaging device includes a flattening layer (17), a color filter (18), and a flattening layer on a semiconductor substrate (14) having a photoelectric conversion element (19) formed on the surface thereof. (16), an undercoat layer (13), a microlens pattern (11), and a resin layer (12) having an infrared absorbing function are sequentially formed.

In the solid-state image pickup device according to the present invention, the concave portion (15) is formed at the position of the gap between the microlens patterns on the surface of the undercoat layer (13), and the infrared absorbing function provided in the concave portion (15). And the resin layer (12) having an infrared absorbing function formed so as to cover the skirt of the microlens pattern (11), the scattered light of the light incident on the inter-lens gap and the microscopic The oblique light incident on the skirt of the lens is cut, and the resin layer (12) having an infrared absorbing function disposed in the recess (15) cuts the reflected light from the inter-lens gap to improve the image quality of the input image. Is to improve.

In the present invention, the microlens pattern means a bare lens before the resin layer having the infrared absorbing function is provided, and the microlens means the lens after the resin layer having the infrared absorbing function is provided. means. The inter-lens dimension refers to the dimension of the microlens pattern gap (W1) in the side direction of the microlens pattern.
Further, the dimension of the inter-lens gap (W2) of the microlens will be simply referred to as the gap dimension hereinafter. The gap dimension refers to the dimension between the inflection points with the position of the inflection point from the curved surface of the microlens to the concave portion as a guide. In addition, the depth of the concave portion roughly indicates the depth (D) from the inflection point from the curved surface of the microlens to the concave portion to the bottom of the concave portion. Further, the resin concave portion is a valley portion (2) between the inflection points on the concave portion surface where the resin layer having an infrared absorbing function is arranged.
6). The film thickness of the resin layer having an infrared absorbing function is, for example, an average film thickness when formed on a flat silicon substrate as a typical film thickness on a surface having irregularities such as a microlens pattern. It is represented by "average film thickness".

The resin layer having an infrared absorbing function in the present invention is selectively thin on the microlens pattern,
It is selectively thickly arranged on the gap between the microlens patterns. It is not desirable to dispose a light-absorbing thin film on the microlens pattern,
I want to make this thin film as thin as possible. For example, by using a resin containing a plurality of infrared absorbing agents and having an infrared absorbing function, the resin can be arranged in a thin film of about 0.01 μm to 0.1 μm.

This is because, for example, when a coating solution is prepared by using a plurality of infrared absorbing agents as light absorbing agents, fine filtration of at least 0.2 μm or less is possible,
This is because it becomes possible to apply a uniform thin film. When a coating solution is prepared using, for example, a pigment as the light absorber, it is affected by the pigment particles, such fine filtration cannot be performed, and it becomes impossible to apply a uniform thin film.

As described above, by selectively thinly coating the microlens pattern with the resin layer having an infrared absorbing function, the microlenses are affected even if the content of a plurality of infrared absorbing agents is increased. Is less,
Therefore, it is possible to dispose a resin having an infrared absorbing function with a high content of a plurality of infrared absorbing agents on the gap between the microlens patterns. By increasing the content of the plurality of infrared absorbers, it is possible to increase the light absorption in the visible region of the plurality of infrared absorbers, the scattered light of the light incident on the inter-lens gap of the microlens or , It effectively cuts the oblique light that enters the skirt of the microlens, which has a poor light collection efficiency, and effectively cuts the reflected light from the inter-lens gap.

The surface shape of the resin layer having an infrared absorbing function formed on the gap between the microlens patterns has a micro-rough surface, a matte surface or a curved surface so that the reflection component of light in a specific direction is not increased. surface,
That is, it is desirable that the surface is not smooth.

The infrared absorption function required in the present invention is C
Since it is intended for solid-state imaging devices such as CDs and CMOSs, it is desirable to have large absorption in the infrared region of 700 nm to 1100 nm and small flat absorption in the visible region of 400 nm to 700 nm. Further, there is no infrared absorbing agent having absorption in a wide range in the infrared region, and it is desirable to use a mixture of a plurality of infrared absorbing agents. As the infrared absorber, a color filter, which is a component of the solid-state image sensor,
It is desired that the flattening film, the undercoat layer, the microlenses, and the like have heat resistance of about 180 ° C. to 250 ° C., which is the temperature at which the organic resin is completely hardened. Results of studies by the present inventors, phthalocyanine compounds, diimonium compounds,
It was found that the azo compound is superior to the infrared absorbers such as the polymethine compound, the cyanine compound and the anthraquinone compound.

The resin having an infrared absorbing function of the present invention is
A resin having a refractive index similar to that of the microlens pattern may be used, but it is desirable that the refractive index be low in order to suppress light reflection and rereflection on the microlens surface. As a result of analysis by the present inventors, it has been found that the reflected light from the non-aperture portion of the microlens (that is, the gap between the microlens patterns) is more problematic than the reflected light from the microlens. From this point, it is desirable that the refractive index of the resin having the infrared absorbing function is lower than that of the microlens pattern. In a system in which an infrared absorber such as a dye is dispersed in a low refractive index resin, the apparent refractive index is higher than that of the low refractive index resin,
It is also possible to restore the original low refractive index by increasing the transmittance of the infrared absorber in the visible region by decoloring it by heat treatment, ultraviolet treatment, alkali dipping treatment, etc. in the process of manufacturing a solid-state imaging device.

The resin material used in the present invention, including the material of the microlens pattern and the material of the undercoat layer, has a high transmittance in the visible region and has practical reliability such as heat resistance, light resistance and heat resistance cycle. Good and not particularly limited. For example, acrylic resin, epoxy resin, polyester resin, urethane resin, melamine resin, urea resin, phenol resin, or copolymers thereof can be used. For the material of the microlens pattern
Phenol-based, phenol novolac-based, or styrene-based photosensitive resins are typically used. Alternatively,
A low molecular weight melamine-epoxy copolymer may be used.

The present invention is an expensive method such as vacuum film formation,
There is a merit that a resin having an infrared absorption function can be formed by a low cost and simple method such as spin coating without taking a complicated process of photolithography.
In order to stably reproduce the resin layer having an infrared absorption function in the submicron region of m or less, sufficient condition setting is indispensable.

When a resin layer having an infrared absorbing function is formed on the microlens pattern by coating, this coating solution may flow into the gap between the microlens patterns and damage the lens shape. In order to avoid this, it is preferable that the surface of the gap between the microlens patterns is previously dug by dry or wet etching. When etching the surface of the gap between microlens patterns in advance,
It is necessary to selectively etch the undercoat layer with respect to the microlens pattern. That is, when the etching rate of the microlens pattern is higher than that of the undercoat layer, the etching of the microlens pattern precedes, which deteriorates the lens shape. Therefore, it is preferable that the etching rate of the undercoat layer is higher than the etching rate of the microlens pattern.

Further, by using a resin having a good heat flow property as the resin having the infrared absorbing function, after coating the resin layer having the infrared absorbing function on the microlens pattern,
It is also possible to raise the temperature all at once to a temperature at which the resin has flowability, fluidize the resin layer, and pour the resin into the recesses between the microlens patterns to selectively form the resin. Alternatively, by using a resin liquid having a high cohesive force such as having thixotropy, a resin having a relatively thick infrared absorbing function can be formed on the microlens pattern.

FIG. 2 is a plan view of the solid-state image pickup device in FIG. FIG. 3A is a cross-sectional view showing the concave portion (24) in the diagonal direction of the microlens (microlens pattern + resin layer having an infrared absorbing function) (21) in FIG. FIG. 3B shows a side recess (2
It is sectional drawing which shows 5) by BB 'cross section. In the present invention, since the depth of the concave portions between the microlens patterns and the properties of the coating liquid of the resin layer having an infrared absorption function disposed on the microlens patterns can be adjusted, the microlens (microlens pattern + infrared absorption) can be adjusted. The depth (D1) of the concave portion in the diagonal direction of the resin layer having a function) and the depth (D2) of the concave portion in the side direction can be arbitrarily set at a practical level. Further, the difference between the depth (D1) of the concave portion in the diagonal direction and the depth (D2) of the concave portion in the side direction can be adjusted to be large or small. This means that the lens aberration can be adjusted to some extent.

If a resin having a strong pseudo-collection property is adopted for the resin layer having an infrared absorbing function, the lens shape can be emphasized (formed into a rounder shape), or the refractive index of the resin layer having an infrared absorbing function can be increased. By adjusting, the reflection of light on the lens surface can be adjusted to some extent. In addition, a material for imparting thixotropy or a surfactant may be added to the coating liquid for the resin layer having the infrared absorbing function. Further, if the refractive index of the microlens pattern and the resin used for the resin layer having the infrared absorbing function are the same, the lens design can be simplified.

Further, according to the present invention, the resin layer having an infrared absorbing function is formed extremely thin on the microlens pattern, and conversely, it is formed thick on the concave portion in the adjacent side direction of the microlens pattern to improve the light absorption property. It has a feature in having it. As described above, this light-absorbing property is obtained by disposing a thin resin layer having an infrared absorbing function selectively on the microlens pattern so that the microlens can be formed even if the content of a plurality of infrared absorbing agents is increased. Therefore, it is possible to dispose a resin layer having an infrared absorbing function with a high content of a plurality of infrared absorbing agents on the gap between the microlens patterns. By increasing the content of the plurality of infrared absorbers, it is possible to increase the light absorption in the visible region of the plurality of infrared absorbers, the scattered light of the light incident on the inter-lens gap of the microlens or , It effectively cuts the oblique light that enters the skirt of the microlens, which has a poor light collection efficiency, and effectively cuts the reflected light from the inter-lens gap.

The film thickness after application of the resin layer having an infrared absorbing function and the filling degree of the recesses are determined by the polarity of the solvent, the cohesive force of the resin used, the thixotropy, the presence or absence of a surfactant and the amount added, the liquid temperature and the substrate temperature. It is affected by the base condition, coat condition, etc. As a result of intensive studies, the present inventors have found that the resin layer having an infrared absorbing function needs to have an average film thickness (average film thickness after hardening) of 0.3 μm or less. . If the film thickness exceeds 0.3 μm, the valleys (resin recesses) on the surface of the recess in which the resin layer having the infrared absorbing function is provided are too filled, and a high aperture ratio (narrow gap) cannot be obtained. For the following average thin films,
Since the resin coating solution is a dilute solution system, it becomes unstable and it is difficult to form a uniform film during coating.

Further, since the concave portions between the microlens patterns are more likely to be filled in the concave portions in the side direction than in the diagonal direction of the microlens pattern, it is necessary to pay attention to the concave portions in the side direction in order to control the narrow gap. The filling degree of the concave portion in the lateral direction depends on the properties of the coating liquid and the coating conditions as described above, but it is only necessary to consider the filling degree of 20 times at maximum to the filling degree of at least 1.5 times. The inventors have found.

Therefore, the depth of the recesses to be formed on the surface of the undercoat layer in the lateral direction between the microlens patterns before applying the resin layer having the infrared absorbing function is 20 times the maximum of 0.3 μm. From 6.0 μm to a minimum of 0.
It is sufficient to consider 0.05 μm, which is 1.5 times 03 μm. However, if the depth of the recess is greater than 1.5 μm, unevenness is likely to occur during application of the resin layer having an infrared absorption function, which is not practical, so the depth of the recess is 1. It can be said that the range of 5 μm to 0.05 μm is preferable.

The preformed recess shown above is
Although it is not necessary to form this, it is preferable to form it from the viewpoint of improving the aperture ratio of the resin lens. The above method is a method of forming the light absorbing resin extremely thin on the resin lens, but according to another manufacturing method of the present invention such as dry etching after forming the resin layer having an infrared absorbing function, the microlens is used. It is also possible to make the thickness of the resin layer having the infrared absorbing function on the pattern almost zero.

As a method of forming such a concave portion, a deep concave portion is formed by subjecting the resin of the undercoat layer to the undercoat layer formed as a base of the microlens pattern by ashing or dry etching with high anisotropy. The method of forming is a simple method.
The microlens pattern is formed by using a known photolithography technique and heat flow technique using a photosensitive resin material. The resin layer having an infrared absorbing function is applied so as to cover the entire surface. However, when the resin layer having an infrared absorbing function is applied, excess resin liquid is dropped into the recesses so that the microlenses are filled in the lateral direction. Is small and has a narrow gap to improve the aperture ratio of the lens.

Therefore, as described above, in the dry etching process, the etching amount of the undercoat layer needs to be suppressed to an amount from 0.05 μm to at most 1.5 μm. Further, in the present invention, in order to maintain the shape of the microlens, the etching rate of the microlens pattern needs to be slower than that of the material of the undercoat layer. From this viewpoint, the etching rate of the resin material of the undercoat layer used in the present invention becomes important together with the optical characteristics such as the refractive index of the material.

In order to utilize the present invention more effectively, the inter-lens dimension in the side direction of the microlens pattern is set to 0.
It is important to process to 6 μm or less, for example, 0.5 μm to 0.1 μm. In the present invention, since it is a technology of a fine region of 0.3 μm or less, that is, a semiconductor level, it is preferable to form the microlens pattern with a dimension between lenses of 0.6 μm or less. When the inter-lens dimension is 0.7 μm or more, for example, 1 μm, the thickness of the resin layer having the infrared absorbing function in the concave portions between the microlens patterns tends to be small, and the resin layer enters the interlens gap of the microlens. The effect of cutting the scattered light of the light and the oblique light incident on the hem part is slightly diminished.

The dimension between lenses is formed to be 0.6 μm or less,
By forming a large film thickness in the recesses between the microlens patterns of the resin layer having an infrared absorbing function, it becomes extremely easy to reduce noise such as smear. Note that the present inventors have found that the reflected light / re-reflected light that causes noise can be suppressed by making the inter-lens gap small (narrow) or forming the lens thick in an aspherical shape.

The film thickness of the resin layer having an infrared absorbing function is
If the film thickness is 0.3 μm or less, the lens shape after etching can be maintained and the film thickness of the resin layer having the infrared absorbing function on the microlens pattern can be thinned. The thicker the film exceeds 0.4 μm, the more difficult it becomes to reproduce the lens matrix and the resin recesses become flat, leaving a resin layer having an infrared absorbing function on the microlens pattern, which may reduce effective light transmission. .

An organic resin thin film having a thickness of 0.3 μm or less
When forming by a general and low cost coating method such as spin coating, for example, it is necessary to reduce the solid content ratio of the resin to greatly reduce the viscosity of the coating liquid. However, if the solid content ratio is lowered too much, the resin content will be quasi-collected and become land-like when the coating liquid is dried. Alternatively, it becomes unstable due to the dilute solution, and the resin is already quasi-assembled in the solvent solution, so that a uniform film cannot be formed. Practically, the lower limit of the average film thickness of the light absorbing resin is 0.03 μm. In addition, a surfactant may be added to the coating liquid in order to improve coatability and dispersibility, a plurality of solvent species may be mixed, or the molecular weight of the resin or another resin may be added. Further, as a pretreatment for coating, light etching treatment, plasma treatment, ultraviolet cleaning or the like may be performed.

The resin layer having an infrared absorbing function in the present invention is a film that is as thin as possible (for example, 0.1 μm or less) on the microlens pattern, and can secure infrared and visible light absorbing performance in the gap between the microlens patterns. It is desirable to arrange with a thickness. However, in the method of disposing the resin layer having an infrared absorbing function including the infrared absorbing agent by coating, a thin film of the resin layer having an infrared absorbing function is formed on the microlens pattern.

In general, since the infrared absorbing material has some light absorption in the visible region, the microlens, although a thin film, has absorption in the visible region, which is not desirable. Therefore, in the present invention, after disposing a resin layer having an infrared absorbing function, decolorizing a plurality of infrared absorbents contained in the resin layer having an infrared absorbing function on the microlens pattern, the transmittance of the visible region It is characterized by increasing. It is possible to decolorize a plurality of infrared absorbers, for example, by immersing them in an organic solvent, a mixed liquid of an organic solvent and an alkali, a strong alkaline aqueous solution, or by exposing to strong ultraviolet light.

Further, according to the present invention, after the resin layer having the infrared absorbing function is provided, the resin layer having the infrared absorbing function on the microlens patterns is removed, and the gap between the microlens patterns and the hem of the microlens pattern are removed. The resin layer having an infrared absorbing function is left in the part. After the resin layer having the infrared absorbing function is formed, if the resin layer having the infrared absorbing function of the thin film of the microlens is removed by dry etching or the like, the light absorbing effect is practically eliminated on the microlens. Alternatively, it is possible to remove only the thin film of the resin layer having the infrared absorbing function on the microlens pattern by a method such as dry etching after formation of the resin layer having the infrared absorbing function, or immersion in an organic alkali stripping solution. .

In general, dry etching using a positive resist is performed in order to remove the resin on the electrode pads in almost the final process of the process of processing an image pickup device such as a CCD. After this dry etching, there is a stripping step using an organic solvent, an organic alkali or the like to remove the positive resist. In this peeling process, it is easy to remove the ultrathin film of the light absorbing resin at the same time as the positive resist. Further, an infrared absorber may be contained in a transparent resin having a refractive index lower than that of the microlens pattern to form an optical thin film having an antireflection effect on the microlens pattern.

[0045]

EXAMPLES Examples of the present invention will be described below. Example 1 FIG. 1 is a sectional view showing a solid-state image sensor according to Example 1. As shown in FIG. 1, the solid-state imaging device includes a flattening layer (17), a color filter (18), and a flattening layer on a semiconductor substrate (14) having a photoelectric conversion element (19) formed on the surface thereof. (16), an undercoat layer (13), a microlens pattern (11), and a resin layer (12) having an infrared absorbing function are sequentially formed.

In the solid-state image pickup device according to the present invention, the concave portion (15) is formed at the position of the gap between the microlens patterns on the surface of the undercoat layer (13), and the infrared absorbing function provided in the concave portion (15). And the resin layer (12) having an infrared absorbing function formed so as to cover the skirt of the microlens pattern (11), the scattered light of the light incident on the inter-lens gap and the microscopic The oblique light that enters the skirt of the lens is cut off, and the reflected light from the inter-lens gap is reduced to improve the image quality of the input image.

This microlens pattern (11) is
An array pitch of 3.3 μm and a microlens pattern gap (W1) of 0.2 μm were made corresponding to the array of the photoelectric conversion elements (19). The microlens pattern is made of phenolic resin and has a height of 1.2 μm. A thin layer of a resin layer (12) having an infrared absorbing function is provided on the microlens pattern.

The inter-lens gap (W2) after forming the resin layer (12) having an infrared absorbing function is about 0.2 μm.
And there is a narrow gap. The thickness of the resin layer having an infrared absorbing function in the concave portions of the microlens pattern is 0.
The thickness is slightly larger than 6 μm, which is sufficient for cutting scattered light and oblique light. The thickness (T) of the thin layer of the resin layer having the infrared absorbing function on the surface (convex portion) of the microlens pattern is about 0.08 μm after the resin layer having the infrared absorbing function is hardened. It is thick.

FIG. 2 is a plan view of the solid-state image sensor according to the first embodiment. 3A is a cross-sectional view of the concave portion (24) of the microlens (21) in FIG. 2 in the diagonal direction taken along the line AA ′, and FIG.
It is shown in the B ′ cross section. As shown in FIGS. 2 and 3, a diagonal search (D
1) is about 0. 0 from the search for the concave portion in the side direction (D2).
It is shown that a recess is formed deeply by 3 μm and the gentle curvature of the lens in the AA ′ direction is complemented by the deep recess. By forming a deep recess and arranging a resin layer that has an infrared absorption function, the aperture ratio is improved and at the same time, unnecessary reflection of oblique light incident on the image sensor is mitigated, and smear is eliminated. Can be provided.

FIGS. 4A to 4E are explanatory views showing in cross section the method for manufacturing a solid-state image pickup device according to the present invention. First, an undercoat layer (13) of epoxy resin is formed on a semiconductor substrate having a photoelectric conversion element, a flattening layer, a color filter, a flattening layer, etc. formed on the surface thereof by a known technique.
Was formed by spin coating.

Next, as shown in FIG.
After the coating layer (13) was hardened, a photosensitive phenolic resin (10) (380R (trade name) manufactured by JSR Corporation) was applied and formed so that the film thickness after drying was 1.1 μm. Through a high-precision photomask (reticle manufactured by Toppan Printing Co., Ltd.), exposure is performed using a stepper and subsequent development is performed.
A 0.4 μm gap (44) shown in (B) was provided.

Next, heat flow treatment is performed by heating on a hot plate at 180 ° C. for 3 minutes, the gap between microlens patterns (W1) is 0.2 μm, the film thickness of the microlens pattern (height of the microlens pattern). (4
1) A microlens pattern (11) having a size of 1.35 μm was formed. In the heat flow treatment, the rectangular shape after development of this layer is flown by 0.1 μm on one side, but if the flow amount is not controlled to 0.2 μm or less, unevenness due to sticking of microlenses will occur. .

Next, as shown in FIG. 4 (D), O2 gas was introduced by a dry etching apparatus to a pressure of 20P.
a, RF power was 1 kW, substrate temperature was room temperature, and etching time was 25 seconds to form recesses (15) having a depth of 0.5 μm between the microlens patterns. The height of the microlens pattern was 1.2 μm. The height (42) of the microlens pattern is initially 0.5 μm lower than the height of the lens, which is reduced by etching. The height and curvature of the lens may be optimized according to the optical positional relationship between the photoelectric conversion element and the lens, and a process design that allows for the reduction due to etching should be made in advance.

The etching rate of the resin used in Example 1 is shown in Table 1. In each case, the etching rate in oxygen plasma after hardening was shown by comparison with the photosensitive phenolic resin which is the material of the microlens pattern. The higher the etching rate, the faster the etching.

[0055]

[Table 1]

As shown in Table 1, since the etching rate of the photosensitive phenolic resin which is the material of the resin lens is lower than that of the epoxy resin, the lens shape can be maintained and the change of the lens curvature can be reduced even if the etching proceeds. In addition, since the epoxy resin, which is the material for the undercoat layer, has a high etching rate, it is possible to deeply process the concave portions in the diagonal direction between the microlens patterns. As a result, the light absorbing resin can be selectively formed in the concave portions between the microlens patterns, the lens effect can be complemented, and the effect of eliminating smear can be provided.

Next, as shown in FIG. 4 (E), after etching, an infrared ray containing 5% of an infrared absorbing agent in a fluorine-based acrylic resin having a refractive index of 1.46 was formed so as to cover the microlens pattern and the concave portion. Resin with absorption function,
Coating was performed with an average film thickness of 0.1 μm. Infrared absorber
Phthalocyanine compounds (Yamamoto Kasei), diimonium compounds (Nippon Kayaku), azo compounds (Hakko Chemical)
The mixture was used. As a result, the film thickness of the resin layer having an infrared absorbing function formed in the concave portion between the microlens patterns is 0.6 μm, which is a film thickness sufficient to cut oblique light and scattered light, and is formed on the black lens pattern. Was formed with a resin layer having an infrared absorbing function with a thickness of about 0.08 μm.

After the final step of immersing the solid-state image pickup device in an organic alkaline solution, the infrared absorbing agent on the surface of the microlenses is almost decolorized, and at the same time, the gap between the microlens patterns is a black color capable of absorbing visible light and infrared rays. It was possible to obtain an image sensor in which the infrared absorbing resin of No. 1 was formed. In addition, in Example 1, an ultraviolet absorber, a quencher, or the like is not added to the resin having an infrared absorbing function, but these may be added to improve light resistance. Alternatively, a resin layer containing an ultraviolet absorber may be separately formed.
Further, the infrared absorbent may be contained in the undercoat layer, the flattening layer, the color filter and the like which include the microlens pattern and are located under the microlens pattern.

[0059]

The present invention provides a solid-state imaging device in which at least an undercoat layer and a plurality of microlenses are sequentially provided on a semiconductor substrate on which a plurality of photoelectric conversion elements are formed. Since it is a microlens that is selectively thin and is thick on the gap between the microlens patterns and is coated with a resin layer having an infrared absorbing function, the scattered light of the light entering the gap between the lenses and the light collection efficiency A solid-state imaging device that does not increase noise such as smear due to oblique light incident on the skirt of a microlens, which is not good, and greatly reduces ghosts due to reflected light from the inter-lens gap to improve image quality.

Further, according to the present invention, since the surface of the resin layer having an infrared absorbing function disposed on the gap between the microlens patterns is not smooth, the reflection component of the light in the specific direction does not become strong. Further, the resin layer having an infrared absorbing function,
It is a resin containing a plurality of infrared absorbers, and since the plurality of infrared absorbers are infrared absorbers selected from a phthalocyanine compound, a diimonium compound, and an azo compound, the infrared region is 700 nm to 1100 nm. It has a large absorption and has a heat resistance suitable for the constituent elements. Moreover, since the refractive index of the resin layer having the infrared absorbing function is lower than the refractive index of the microlens pattern, it is possible to suppress reflection and rereflection of light on the surface of the microlens.

According to the present invention, in the method for manufacturing a solid-state image pickup device described above, a recess is formed on the surface of the undercoat layer at the position of the gap between the microlens patterns before disposing the resin layer having an infrared absorbing function, Since a resin layer with an infrared absorption function is provided, noise such as smear caused by scattered light that enters the interlens gap of the microlens or oblique light that enters the hem of the microlens, which has poor light collection efficiency, increases The present invention provides a method for manufacturing a solid-state imaging device in which the ghost and the like due to the reflected light from the inter-lens gap are significantly reduced and the image quality is improved.

Further, in the present invention, since the etching rate of the undercoat layer is higher than the etching rate of the microlens pattern, the undercoat layer is not selectively etched with respect to the microlens pattern and the lens shape is not damaged. Further, since the infrared absorbent is decolorized or the resin layer having the infrared absorbing function on the microlens pattern is removed after disposing the resin layer having the infrared absorbing function, solid-state imaging with enhanced transmittance in the visible region. This is a method for manufacturing an element.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a solid-state image sensor according to the present invention.

FIG. 2 is a plan view of the solid-state image sensor in FIG.

FIG. 3A is a cross-sectional view showing a diagonal concave portion of the microlens in FIG. 2 taken along the line AA ′. (B)
[Fig. 4] is a cross-sectional view showing a concave portion in the side direction by a BB 'cross section.

4 (A) to 4 (E) are explanatory views showing in cross section the method for manufacturing a solid-state image sensor according to the present invention.

[Explanation of symbols]

10 ... Photosensitive phenolic resin 11 ... Micro lens pattern 12 ... Resin layer having infrared absorbing function 13 ... Undercoat layer 14 ... Semiconductor substrate 15 ... Recessed undercoat layer 16 ... Flattening layer 17 ... Flattening layer 18 ... Color filter 19 ... Photoelectric conversion element 21 ... Micro lens 24 ... Diagonal recess 25 ... a concave portion in the side direction 26 ... Resin recess (valley between inflection points) 41, 42 ... Height of microlens pattern D1 ... Depth of concave part in diagonal direction D2 ... Depth of recess in side direction T ... Thickness of thin resin layer having infrared absorbing function W1 ... Gap between micro lens patterns W2 ... Gap between micro lenses

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H042 AA03 AA06 AA09 AA15 AA21                 2H048 CA04 CA09 CA12 CA19 CA22                       CA24                 2K009 BB14 BB15 CC21 DD02 DD12                       EE00                 4M118 AA05 AB01 GC08 GC11 GD04                       GD07 GD20

Claims (9)

[Claims] 1. A solid-state imaging device comprising a semiconductor substrate on which a plurality of photoelectric conversion elements are formed, and at least an undercoat layer and a plurality of microlenses in order, wherein the microlenses are selectively thin on the microlens pattern. A solid-state image pickup device, characterized in that a resin layer having a thick and infrared absorbing function is selectively provided on the inter-pattern gap. 2. The solid-state image pickup device according to claim 1, wherein the surface of the resin layer having an infrared absorbing function provided on the gap between the microlens patterns is not smooth. 3. The solid-state imaging device according to claim 1, wherein the resin layer having an infrared absorbing function is a resin containing a plurality of infrared absorbing agents. 4. The solid-state image pickup device according to claim 3, wherein the plurality of infrared absorbers are infrared absorbers selected from a plurality of phthalocyanine compounds, diimonium compounds and azo compounds. 5. The solid according to claim 1, wherein the resin layer having an infrared absorbing function has a refractive index lower than that of the microlens pattern. Image sensor 6. A method of manufacturing a solid-state imaging device, comprising: a semiconductor substrate having a plurality of photoelectric conversion elements formed thereon, and at least an undercoat layer and a plurality of microlenses in order. A microlens that is selectively thin and is thick on the gap between the microlens patterns to cover the resin layer having an infrared absorbing function, wherein the resin layer having an infrared absorbing function contains a plurality of infrared absorbing agents. Before forming the resin layer having the infrared absorbing function, a recess is formed on the surface of the undercoat layer at the position of the gap between the microlens patterns, and the resin layer having the infrared absorbing function is provided by coating. And a method for manufacturing a solid-state image sensor. 7. The method for manufacturing a solid-state imaging device according to claim 6, wherein the etching rate of the undercoat layer is higher than the etching rate of the microlens pattern. 8. After disposing the resin layer having the infrared absorbing function, a plurality of infrared absorbing agents contained in the resin layer having the infrared absorbing function on the microlens pattern are decolorized to enhance the transmittance in the visible region. The method for manufacturing a solid-state imaging device according to claim 6 or 7, characterized in that. 9. After disposing the resin layer having the infrared absorbing function, the resin layer having the infrared absorbing function on the microlens patterns is removed, and infrared rays are provided on the gaps between the microlens patterns and on the skirts of the microlens patterns. The method for manufacturing a solid-state imaging device according to claim 6, wherein the resin layer having an absorbing function is left.