JP5200358B2 - Imaging device, solid-state imaging device, and manufacturing method thereof - Google Patents

Description

  The present invention relates to a solid-state imaging device equipped with optical filters having different characteristics corresponding to a plurality of pixels, a manufacturing method thereof, and an imaging device using the solid-state imaging device.

In general, a solid-state imaging device such as a CMOS image sensor or a CCD image sensor is provided with a color filter that transmits a specific color component light for each of a plurality of pixels.
Also, in such a solid-state imaging device, external light is efficiently incident on the photodiode (photoelectric conversion means) of each pixel by the light collecting means. Techniques for improving the light collection efficiency by using concave lenses, in-layer convex lenses, and the like have been proposed.
However, in recent years, even with a condensing technology that combines lenses, the decrease in the number of electrons per pixel that is the source of the output signal of the solid-state imaging device is compensated by the decrease in the absolute amount of incident light accompanying the reduction in the unit pixel size. However, the sensitivity of the solid-state imaging device tends to decrease. This reduction in sensitivity deteriorates the ratio (S / N ratio) between the signal output and light shot noise, dark current noise, which is inherent noise generated in the pixel, noise mixed during transfer, and the like. It is causing a decline.
In order to compensate for this decrease in sensitivity, the rate at which electrons are converted into voltage, so-called conversion efficiency, is increased. However, light shot noise, dark current noise, and noise mixed during transfer are also amplified. There is a problem that the / N ratio is not improved.

  On the other hand, as a technique for improving the sensitivity, a signal of a pixel that is not spectrally separated by a color filter is used as a luminance signal, or a signal of a pixel having a low S / N ratio is used not only in the visible light near the pixel but also in the near infrared region. There has been proposed a technique such as replacement with a signal having a high S / N ratio obtained from a pixel without a color filter that also transmits light of the wavelength (so-called IR fitting). In order to use these methods, for example, as shown in FIG. 5A, an unfiltered portion 14 having no filter is arranged between the three types of color filters 11, 12, 13, or FIG. ), A color filter array in which a non-filter part 23 having no filter is disposed between the two types of color filters 21 and 22 is used.

  By the way, as a color filter material, generally, a negative color resist in which an acrylic resin in which a pigment is dispersed is made photosensitive is used. In this color resist, polymerization of the photosensitive composition proceeds by exposure light, but the degree of polymerization in the vicinity of the interface with the base affects the adhesion of the formed pattern. In particular, since the color resist contains a dye, exposure light does not easily reach the interface with the base, and there is a problem that the adhesion is insufficient due to insufficient polymerization and the pattern is easily peeled off.

FIG. 6 shows a general RGB primary color filter arrangement.
In this color filter array, a Green filter 31 is arranged in a checkered pattern, and a Red filter 32 and a Blue filter 33 are arranged therebetween.
In such a filter, by forming a pattern with Green as the first color, not only the contact with the base but also the patterns are in contact with each other at the four corners, thereby improving the adhesion and making it difficult to peel off. . Further, since the second and third colors are in close contact with the side wall of the green pattern, sufficient adhesion can be secured to such an extent that the second and third colors do not peel off.

However, in the case of the color filter array as shown in FIG. 5, a part where the color filter is present in isolation with the non-filter portion interposed is generated, and the color filter is peeled off due to insufficient adhesion. In addition, due to the reduction in the adhesion area of the color filter pattern accompanying the reduction in pixel size, the lack of adhesion is promoted.
For improving the adhesion of the color filter, various methods have been proposed so far, such as a method of forming a filter after etching the surface of the underlying layer (see, for example, Patent Document 1). The effect on is not enough.
JP 2001-28432 A

  As described above, in a configuration in which pixels without a color filter are arranged to improve sensitivity, there is a problem in that the adhesion between the color filter and the base layer is lowered and peeling is likely to occur.

  Accordingly, an object of the present invention is to provide an imaging device, a solid-state imaging device, and a method for manufacturing the same, in which separation does not occur even in an isolated color filter pattern arrangement and sensitivity can be easily improved.

In order to achieve the above-described object, a solid-state imaging device of the present invention includes a pixel array unit in which a plurality of pixels each having a photoelectric conversion unit are arranged, and an optical filter layer disposed above the pixel array unit. The optical filter layer has a transparent resin pattern containing a transparent resin, and a spectral filter pattern containing the transparent resin and a pigment having the same composition as the transparent resin pattern,
The transparent resin pattern is not more than the film thickness of the spectral filter and is arranged in a checkered pattern corresponding to the arrangement of the pixels, above the pixel array portion where the transparent resin pattern is not arranged, The spectral filter is patterned so as to be embedded in every other vertical and horizontal pixels of the pixel so as to be in close contact with the side wall surface of the transparent resin pattern .

The image pickup apparatus of the present invention includes a solid-state image pickup device including a pixel array unit in which a plurality of pixels each having a photoelectric conversion unit are arranged, and an optical filter layer disposed above the pixel array unit, and the optical The filter layer includes a transparent resin pattern containing a transparent resin, and a spectral filter pattern containing the transparent resin and a pigment having the same composition as the transparent resin pattern, and the transparent resin pattern is formed of the spectral filter. It is less than the film thickness and is arranged in a checkered pattern corresponding to the arrangement of the pixels so as to be in close contact with the side wall surface of the transparent resin pattern above the pixel array portion where the transparent resin pattern is not arranged. In addition, the spectral filter is patterned in a state of being embedded every other vertical and horizontal pixels of the pixel .

The manufacturing method of the present invention includes a step of forming a transparent resin pattern containing a transparent resin in a checkered pattern corresponding to the arrangement of the pixels above the pixel array unit in which a plurality of pixels having photoelectric conversion units are arranged. The transparent resin pattern contains the transparent resin and the dye having the same composition as the transparent resin pattern above the pixel array portion where the transparent resin pattern is not disposed, and is in close contact with the side wall surface of the transparent resin pattern. And a step of patterning the spectral filter that is thicker than the resin pattern in a state of being embedded every other vertical and horizontal pixels .

According to the solid-state imaging device and the imaging device of the present invention, in a solid-state imaging device having a pixel that receives light obtained by separating incident light and a pixel that receives light without dispersing the incident light, a spectral filter made of a normal filter material. By configuring the optical filter layer with the filter-free part made of a transparent resin film, the adhesion between the base layer and the filter layer and the adhesion between the filter parts can be improved, and the filter can be prevented from peeling off. It is possible to obtain a solid-state imaging device and an imaging device with high reliability.
Further, in the manufacturing method of the present invention, the optical filter layer is formed from a transparent resin film, and then the spectral filter portion of the optical filter layer is formed from a filter material. The adhesion of the filter can be improved, and peeling during the manufacturing process can be eliminated, and a stable solid-state imaging device can be manufactured.

An embodiment of the present invention provides a filter layer provided on a sensor chip in a solid-state imaging device such as a CCD image sensor or a CMOS image sensor, and a non-filter unit that transmits light from visible light to near-infrared region without dispersing the light. And a color filter portion that performs spectroscopy in the visible light region, and the non-filter portion is formed of a transparent resin pattern obtained by removing a dye from a resin having the same composition as the color filter material.
Thus, by using the same composition resin as the color filter material, it is possible to improve the adhesion between the patterns of each pixel, and pattern formation using the same process as the color filter formation process such as exposure and development can be performed. Is possible. Further, by forming this transparent resin pattern before forming the color filter, it is possible to provide a close contact surface in forming the color filter pattern in which the side wall surface of the transparent resin pattern is isolated, and the adhesion can be improved. In addition, since the transparent resin in the non-filter part does not contain a dye, the exposure light sufficiently reaches the interface with the base and the photopolymerization occurs sufficiently from the pattern surface to the bottom layer, so it has very high adhesion and does not peel off. Hard to occur.
According to the present embodiment, the adhesion of the color filter is improved without introducing a new process, and the color filter pattern is not peeled off in the manufacturing process of the color filter, and a stable color filter can be manufactured.

Hereinafter, specific examples of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing an outline of a solid-state imaging device employed in the present embodiment, and shows an example of a CMOS image sensor.
FIG. 2 is a sectional view showing the element structure around the pixel of the CMOS image sensor shown in FIG.
First, in FIG. 1, the CMOS image sensor of this example includes an imaging region 100 in which a plurality of pixels 110 including photodiodes (photoelectric conversion units) are arranged in a two-dimensional direction on the same chip to form a pixel array unit. A peripheral circuit region 200 formed outside the imaging region 100 is provided.
In the peripheral circuit region 200, a vertical selection drive circuit 210 that supplies various control pulses to the pixel array unit to read out pixel signals for each pixel column, and column signals read from the pixel array unit. A column signal processing unit 220 that performs signal processing such as noise processing, a horizontal scanning circuit 230 that transfers a pixel signal processed by the column signal processing unit 220 to a horizontal signal line 260, and a pixel that is transferred from the horizontal scanning circuit 230 An output processing unit 240 that converts a signal into a video signal and outputs it, a timing generator 250 that supplies a timing signal to each unit, and the like are provided.

Next, as shown in FIG. 2, a laminated film 310 in which various wirings and insulating films are laminated is arranged on a silicon substrate 300, and a color filter 321 and a microlens 322 are arranged thereon.
In the upper layer portion of the silicon substrate 300, a photodiode (PD) 302 is formed in a region isolated by the element isolation portion 301, and an FD 303, various transistors (Tr) 304, and the like are formed in the periphery thereof. In addition, a gate electrode 304A of each transistor 304 is formed on the upper surface of the silicon substrate 300 via a gate insulating film 305, and various wirings 312 are formed in a multilayer structure thereon via an interlayer insulating film 311. .
In addition, a color filter 321 and a microlens 322 are arranged on the interlayer insulating film 311 with a planarizing film 317 interposed therebetween.

Next, the configuration of the color filter layer, which is a feature of the present invention, will be described.
FIG. 3 is a plan view showing the pixel arrangement of the color filter used in the image sensor of this example. 4 is a cross-sectional view showing the layer structure of the color filter shown in FIG. 3, FIG. 4 (a) shows a cross section taken along the line AB in FIG. 3, and FIG. 4 (b) shows a CD in FIG. A line section is shown.
As shown in FIG. 3, in the color filter of this example, three types of color filters 41, 42, and 43 of the RGB three primary color filters are arranged every other vertical and horizontal pixels, similarly to the filter arrangement shown in FIG. ing.
In addition, a pixel portion where no color filter is present is disposed between the color filters 41, 42, and 43. In this example, instead of the conventional non-filter portion 14, it is colorless and transparent using the same composition material as the color filter material. The resin film 44 is disposed.

As shown in FIG. 4, the color filter layer having such a structure is a transparent resin obtained by removing a pigment from a resin having the same composition as that of a color filter material on a base planarizing film 45 formed of a resin or an inorganic film. A film 44 is formed, and a pattern is formed in a state where the color filters 41, 42, and 43 are embedded from the upper surface of the resin film 44.
As a result, each color filter 41, 42, 43 has a close contact surface on the interface of the flattening film 45 and the side wall of the transparent resin film 44, which is more adhesive than the case of forming an isolated color filter pattern of the conventional example. As a result, pattern peeling during pattern formation can be suppressed.

Next, a method for manufacturing such a color filter layer will be described.
First, a transparent resin pattern is formed on the base planarization film by using a lithography technique. In this method, a transparent resin is applied by spin coating, exposure is performed using a mask having a desired pattern in a step-and-repeat exposure apparatus, and then development is performed using an alkaline aqueous solution.
The coating film thickness at this time is such that uneven coating occurs when the color filter material is applied in the next process, or the surface of the formed color filter has a greatly depressed shape. It is desirable to adjust so that it becomes the following.
Here, the transparent resin is a negative photopolymerization color resist, a negative chemically amplified color resist, a positive color resist, or a positive chemically amplified color resist from which a dye is removed. For example, an acrylic or novolac resin is used. For example, CT (trade name) manufactured by FUJIFILM Electronics Materials Co., Ltd. is a resin photosensitive material. Some materials may require bleaching treatment such as irradiation with light.

  Thereafter, color filters are formed in the same manner as in the prior art. First, a resist material to be a filter material is applied on the above-described transparent resin pattern and the underlying flattening film by spin coating, and then prebaked. Next, after performing stepper exposure using i-line (nm) as exposure light, paddle development is performed. The above steps are repeated in the order of Green, Red, and Blue, and then post-baking is performed to form a pattern of three color filters.

As described above, in the image sensor of this example, the color filter layer is formed by the non-filter part that transmits light in the near-infrared region from visible light without dispersing it, and the color filter unit that performs spectroscopy in the visible light region. In the case of configuration, a new resin process is introduced by forming a transparent resin pattern in which the pigment is removed from the color filter material in the no-filter part, and then forming this transparent resin pattern before forming the color filter pixel part. Therefore, the adhesion of the color filter is improved, and the color filter pattern is not peeled off in the manufacturing process of the color filter, and a stable color filter can be manufactured.
As a result, it is possible to manufacture a solid-state imaging device that efficiently uses light incident on the image sensor, and it is possible to provide a solid-state imaging system having a high S / N ratio.

Although the case where the present invention is applied to a CMOS image sensor has been described above, the present invention is not necessarily limited to a CMOS image sensor, and can be applied to a solid-state imaging device such as a CCD image sensor.
The solid-state imaging device is not limited to a CCD image sensor or CMOS image sensor formed on one chip, and may be a module in which a plurality of chips such as an imaging unit and a signal processing unit are packaged together.
The present invention is not limited to a device configured as a solid-state imaging device, and various solid-state imaging devices combined with other functional units (for example, a control unit, an operation unit, a display unit, an image file unit, a communication unit, etc.) It may be a device configured as an imaging device (for example, a camera device, a security system, or a mobile phone). In addition, the imaging target includes one that performs fingerprint detection and the like.
By applying the present invention to these imaging devices, it is possible to obtain the effects of improving the durability and reliability of the imaging unit, reducing the cost by improving the manufacturing yield, and the like, which can provide a high-quality device at low cost. There is.

It is a block diagram which shows the outline | summary of the solid-state imaging device (CMOS image sensor) employ | adopted by embodiment of this invention. It is sectional drawing which shows the element structure of the pixel periphery of the CMOS image sensor shown in FIG. It is a top view which shows pixel arrangement | positioning of the color filter used with the image sensor shown in FIG. FIG. 4 is a cross-sectional view showing the layer structure of the color filter shown in FIG. 3, (a) showing a cross section taken along line AB in FIG. 3 and (b) showing a cross section taken along line CD in FIG. 3. It is a top view which shows pixel arrangement | positioning of the color filter containing a no filter part. It is a top view which shows the pixel arrangement | positioning of a general RGB three primary color filter.

Explanation of symbols

  41, 42, 43 .... color filter, 44..transparent resin film, 45..flattened film, 100..imaging region, 110..pixel, 200..peripheral circuit region, 210..vertical selection drive circuit, 220 ... Column signal processing unit, 230 ... Horizontal scanning circuit, 240 ... Output processing unit, 250 ... Timing generator, 300 ... Silicon substrate, 302 ... Photodiode, 310 ... Multilayer film, 321 ... Color Filter, 322 ... Microlens.

Claims (11)

A pixel array unit in which a plurality of pixels having a photoelectric conversion unit are arranged; and an optical filter layer disposed above the pixel array unit;
The optical filter layer has a transparent resin pattern containing a transparent resin, and a spectral filter pattern containing the transparent resin and a pigment having the same composition as the transparent resin pattern,
The transparent resin pattern is less than or equal to the film thickness of the spectral filter, and is arranged in a checkered pattern corresponding to the arrangement of the pixels,
The spectral filter is patterned above the pixel array part where the transparent resin pattern is not arranged, in a state of being embedded every other vertical and horizontal pixels of the pixel so as to be in close contact with the side wall surface of the transparent resin pattern . Solid-state imaging device. The solid-state imaging device according to claim 1, wherein the transparent resin is a photosensitive material. The solid-state imaging device according to claim 1, wherein a planarizing film is provided as a base of the optical filter layer between the pixel array unit and the optical filter layer. The solid-state imaging device according to claim 1, wherein the spectral filter is a color filter that splits incident light in a visible light region and supplies predetermined color component light to a pixel. A solid-state imaging device having a pixel array unit in which a plurality of pixels having a photoelectric conversion unit are arranged, and an optical filter layer disposed above the pixel array unit,
The optical filter layer has a transparent resin pattern containing a transparent resin, and a spectral filter pattern containing the transparent resin and a pigment having the same composition as the transparent resin pattern,
The transparent resin pattern is less than or equal to the film thickness of the spectral filter, and is arranged in a checkered pattern corresponding to the arrangement of the pixels,
The spectral filter is patterned above the pixel array part where the transparent resin pattern is not arranged, in a state of being embedded every other vertical and horizontal pixels of the pixel so as to be in close contact with the side wall surface of the transparent resin pattern . Imaging device. The imaging device according to claim 5, wherein the transparent resin is a photosensitive material. The imaging apparatus according to claim 5, wherein a planarizing film is provided as a base of the optical filter layer between the pixel array unit and the optical filter layer. The imaging device according to claim 5, wherein the spectral filter is a color filter that splits incident light in a visible light region and supplies predetermined color component light to a pixel. Forming a transparent resin pattern containing a transparent resin in a checkered pattern corresponding to the arrangement of the pixels above the pixel array unit in which a plurality of pixels having a photoelectric conversion unit are arranged;
Above the pixel array portion where the transparent resin pattern is not disposed, the transparent resin and the pigment having the same composition as the transparent resin pattern are contained, and the vertical and horizontal directions of the pixels are in close contact with the side wall surface of the transparent resin pattern. A method of manufacturing a solid-state imaging device, wherein a step of patterning a spectral filter that is thicker than the resin pattern is performed in a state of being embedded every other pixel . The method for manufacturing a solid-state imaging device according to claim 9, wherein a lithography technique is used in the step of forming the transparent resin pattern. After the step of forming the transparent resin pattern, a method for manufacturing a solid-state imaging device according to claim 9 or 10, wherein performing the bleaching process.

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