JPH05110044A - Manufacture of solid same imaging element - Google Patents

Abstract

PURPOSE:To form black filter layers without damaging the flatness of the surface of a base and to manufacture a solid state imaging element having a high performance. CONSTITUTION:An unnecessary part of a dyeingproof material layer 10 formed on the surface of a material layer 8 to be dyed is removed and a part 10a, from which the layer 10 is removed, of the layer 8 is dyed black, whereby black filter layers 11 are formed.

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, and more particularly to a method of manufacturing a solid-state image pickup device having a black filter layer formed on an upper surface of a semiconductor substrate on which a photoelectric conversion element is mounted.

[0002]

2. Description of the Related Art FIGS. 8 to 11 are schematic sectional views showing steps of forming a black filter layer in a conventional solid-state image pickup device. In the figure, reference numeral 1 is a semiconductor substrate, 2 is a photoelectric conversion unit formed of a photodiode mounted on the semiconductor substrate 1, 3 is a separation unit for separating each pixel region, and 4 is a photoelectric conversion unit obtained by the photoelectric conversion unit 2. A CCD (charge-coupled device) transfer unit for transferring signals, 5 is an insulating layer covering these surfaces,
Reference numeral 6 denotes a gate electrode embedded in the insulating layer 5 at a position facing the CCD transfer portion 4, and reference numeral 7 denotes an Al light-shielding film embedded in the insulating layer 5 so as to cover the gate electrode 6.

Next, a process of forming a black filter layer in a conventional solid-state image pickup device will be described with reference to each drawing. First, as shown in FIG. 8, on a semiconductor substrate 1 on which a photoelectric conversion section 2, a separation section 3, a CCD transfer section 4, a gate electrode 6 and the like are formed, as shown in FIG. 9, a natural material such as gelatin or casein is used. An aqueous solution of protein containing about 10% ammonium dichromate is applied to a thickness of about 1 μm by a spin coating method or the like to form the material layer 8 to be dyed. Next, as shown in FIG. 10, the material layer 8 to be dyed is patterned by photolithography to form a predetermined pattern 8a. Finally, the semiconductor substrate 1 on which the pattern 8a is formed is immersed in a dyeing solution prepared under predetermined conditions for a certain period of time, and the pattern 8a is dyed black as shown in FIG. Form.

The black filter layer 9 thus formed can suppress reflection of light incident on the surface of the chip from the Al light-shielding film 7, so that the color filters of red, blue, etc., which will be used as a subsequent process, can be suppressed. At the time of formation, it is possible to suppress distortion and roughness of the dyed pattern formed by photoengraving, so not only can the yield in the filter formation process be improved, but also the reflection of light incident on the chip surface during actual use can be prevented. It is also possible to prevent false signals such as halation and to close the pinholes of the Al light-shielding film 7 so that defective chips can be relieved and the yield of the element itself is improved. Also contribute to.

[0005]

Since the conventional solid-state image pickup device is manufactured by the above-described method, the gap between the upper surface of the black filter layer 9 and the lower surface of the insulating layer 5 shown by A in FIG. Of the black filter layer 9 increases.
Even when there is no step, there is a step of about 2 μm between the surface of the photoelectric conversion part 2 and the Al light-shielding film 7, but the step A becomes 3 μm or more due to the formation of the black filter layer 9, which is a post-process. It becomes difficult to flatten the chip surface, which is a major obstacle to the formation of the color filter layer. In addition, when considering flattening to some extent before forming the black filter layer 9, there may be considered a method of filling only the photoelectric conversion portion 2 or a method of applying a resin having good flatness to a certain thickness. However, in the case of the former, it is unavoidable that the process such as the addition of a photomechanical process becomes complicated, and in the case of the latter, the black filter layer 9 and Al
There is a problem in that a gap is formed between the light-shielding film 7 and the resin layer, which adversely affects the performance of the device itself, such as multiple reflection of light in the chip and occurrence of crosstalk.

The present invention has been made in order to solve the above problems, and provides a manufacturing method capable of obtaining a high-performance solid-state image pickup device by forming a black filter layer while suppressing a step difference on the underlying surface. It is intended to be provided.

[0007]

[Means for Solving the Problems] Claim 1 according to the present invention
The method for manufacturing a solid-state imaging device, comprises a step of forming a material layer to be dyed on an upper surface of a semiconductor substrate on which a photoelectric conversion element is mounted,
The step of forming a transparent and undyed dye-proof material layer on the upper surface of the dye-dyed material layer, the step of removing unnecessary portions of the dye-dyed material layer, and the portion of the dye-dyed material layer from which the dye-proof material layer is removed And a step of forming a black filter layer by dyeing black, and the solid-state imaging device manufacturing method of claim 2 is the dye-proof material layer and the black filter layer in addition to the manufacturing process of claim 1. The method for producing a solid-state imaging device according to claim 3 further includes the step of forming a desired color filter layer on the upper surface of the dye-proofing material layer and the black filter layer. It includes a step of forming a microlens on the upper surface.

[0008]

The method of manufacturing a solid-state image pickup device according to the present invention comprises:
By removing unnecessary portions of the dye-proof material layer formed on the surface of the material layer to be dyed and dyeing the part of the material layer to be dye-proofed, which is dyed black, the base surface is flattened. The black filter layer is formed at the same time.

[0009]

EXAMPLES Example 1. Embodiments of the present invention will be described below with reference to the drawings. 1 to 6 are schematic sectional views showing manufacturing steps of a method for manufacturing a solid-state imaging device according to Embodiment 1 of the present invention. As shown in FIG. 1, the semiconductor substrate 1 has a photoelectric conversion section 2, a separation section 3 and a CCD transfer section 4 formed therein as in the conventional one, and above the CCD transfer section 4. Gate electrode 6 and A via insulating layer 5
The light shielding film 7 is formed. Further, the upper surface is covered with an insulating layer 5 to protect the chip surface.

Next, on the upper surface of such a semiconductor substrate 1,
As shown in FIG. 2, the material to be dyed is applied in a film thickness of about 1 μm and cured by a suitable method to form the material to be dyed layer 8
To form. As the material to be dyed, ammonium bichromate or the like is added in a weight percentage of 10 to 1 in order to impart a negative photosensitivity to a natural polymer such as gelatin or casein.
It is suitable to add about 5%, and in this case, after coating, a method of irradiating UV light on the entire surface to cure is applied.

Dyeing material layer 8 thus formed
As shown in FIG. 3, a dye-proof material layer 10 is formed by applying a material that is transparent to visible light and is not dyed with a dye to the upper surface of the above and cure the material. It is an absolute requirement that this material has a good flatness and is not dyed with a dye.
The material itself does not necessarily require photosensitivity. Although there are various suitable ones, those having photosensitivity per se are simple and suitable for the process.

Specifically, a negative resist such as FVR series manufactured by Fuji Yakuhin Co., Ltd., which is transparent and can be exposed with g rays, is preferable. When a material having no photosensitivity is applied, it is necessary to form the dye-proof material layer 10, and then apply a resist to pattern the material and process it using a method such as dry etching. However, since transparency, heat resistance, stability, etc. are superior to those of the negative resist, it is necessary to judge which one is to be applied according to the required performance. Further, the film thickness is desired to be about 0.5 μm because it is required to sufficiently absorb the irregularities of the base and make the Al light-shielding film 7 as thin as possible.

Subsequently, a mask is applied while leaving the dye-proof material layer 10 only in the portion of the dyed tank 8 that should not be dyed. When a photosensitive resist is used for the dye-proof material layer 10,
The dye-resisting material layer 10 can be directly processed by a normal photoengraving method, but in other cases, a resist is applied on the upper surface of the dye-enhancing material layer 10 and a pattern is formed by the photoengraving method, followed by dry etching or the like The pattern 10 is formed by removing the unnecessary portion of the dye-proof material layer 10 as shown in FIG.
a is formed. In this case, of course, there must be a sufficient etch rate ratio between the dyed material layer 8 and the dye-proof material layer 10. For example, when SOG (spin on glass) is used for the dye-proof material layer 10, a sufficient etching rate ratio is secured by using plasma etching of CF ₄ gas.

Finally, the semiconductor substrate 1 is dipped in a predetermined dyeing solution to dye the material layer 8 to be dyed, which is not covered with the pattern 10a, black to form a black filter layer 11 as shown in FIG. To do. The setting of the dyeing solution is, for example, 60 to 7 when using an acid dye manufactured by Nippon Kayaku Co., Ltd.
The pH of the dyeing solution may be set to 4 at 0 ° C, and a dyeing time of 10 to 20 minutes is sufficient. Further, as shown in FIG. 5, gelatin or casein of the material layer 8 to be dyed expands by dyeing, so that when formed as the black filter layer 11, the film thickness increases by about 10%, but the pattern 1
It is absorbed by the level difference of 0a, the level difference on the chip surface is greatly suppressed, and a surface having very good flatness can be obtained.
Therefore, as shown in FIG. 6, it becomes easy to form the color filter layer 12 on the surface thereof. A protective film 13 covers the surface of the color filter layer 12.

Example 2. Further, the black filter layer 11 does not have a color separation function, that is, it is very useful in the sense that the reflection of light on the chip surface is suppressed even for a solid-state image sensor that does not require the color filter layer 12. Figure 7
As shown in FIG. 5, after the flattening resin layer 14 is formed on the upper surface of the black filter layer 11, the microlenses 15 are effectively formed on the surface of the flattening resin layer 14. Micro lens 15
Is applied in order to improve the sensitivity of the device by condensing wasted light of the light emitted onto the device to the photoelectric conversion unit 2.

Therefore, the microlens 1 with high accuracy
In order to form No. 5, it is necessary to almost eliminate the level difference in the base, and in the past, this level difference was quite large, and therefore it was necessary to make the planarizing resin layer 14 considerably thick (for example, 8 to 10 μm). If the microlenses 15 are formed after the black filter layer 11 is formed in the manufacturing process of Example 1, the flatness of the base is improved, and thus the flattening resin layer 14 must be unnecessarily thick. In addition to facilitating the opening of the bonding pad (not shown) of the flattening resin layer 14, it is possible to reduce the cost by reducing the number of steps, and the solid-state imaging device with a high-performance microlens The device can be manufactured.

[0017]

As described above, according to the present invention, unnecessary portions of the dye-proof material layer formed on the surface of the dye-dyed material layer are removed, and the dye-proof material layer is removed from the dye-proof material layer. Since the black filter layer is formed by dyeing black with, it is possible to obtain a base surface with good flatness,
It is possible to manufacture a high-performance solid-state image sensor.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing a step of forming a photoelectric conversion part and the like on a semiconductor substrate in the manufacturing steps of the method for manufacturing a solid-state imaging device according to Example 1 of the present invention.

FIG. 2 is a schematic cross-sectional view showing a step of forming a material layer to be dyed among the manufacturing steps of the method for manufacturing a solid-state imaging device according to Example 1 of the present invention.

FIG. 3 is a schematic cross-sectional view showing a step of forming a material layer to be dyed among the manufacturing steps of the method for manufacturing a solid-state imaging device according to Example 1 of the present invention.

FIG. 4 is a schematic sectional view showing a step of forming a pattern by removing unnecessary portions of the dye-proof material layer in the manufacturing steps of the method for manufacturing a solid-state imaging device according to Example 1 of the present invention.

FIG. 5 is a schematic sectional view showing a step of forming a black filter layer in the manufacturing steps of the method for manufacturing a solid-state imaging device according to the first embodiment of the present invention.

FIG. 6 is a schematic sectional view showing a step of forming a color filter layer in the manufacturing steps of the method for manufacturing a solid-state imaging device according to Example 1 of the present invention.

FIG. 7 is a schematic cross-sectional view showing a step of forming a microlens in the manufacturing steps of the method for manufacturing a solid-state imaging device according to Example 2 of the present invention.

FIG. 8 is a schematic cross-sectional view showing a step of forming a photoelectric conversion unit and the like on a semiconductor substrate in the manufacturing steps of the conventional method for manufacturing a solid-state imaging device.

FIG. 9 is a schematic cross-sectional view showing a step of forming a material layer to be dyed among the manufacturing steps of the conventional method for manufacturing a solid-state imaging device.

FIG. 10 is a schematic sectional view showing a step of patterning a material layer to be dyed to form a pattern in the manufacturing steps of the conventional method for manufacturing a solid-state imaging device.

FIG. 11 is a schematic sectional view showing a step of forming a black filter layer in the manufacturing steps of the conventional method for manufacturing a solid-state imaging device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2 Photoelectric conversion part 8 Dyeing material layer 10 Dye-proof material layer 10a Pattern 11 Black filter layer 13 Color filter layer 15 Micro lens

Claims (3)

[Claims] 1. A step of forming a material layer to be dyed on an upper surface of a semiconductor substrate on which a photoelectric conversion element is mounted, and a step of forming a transparent and undyed dye-proof material layer on the upper surface of the material layer to be dyed. And a step of removing an unnecessary portion of the dye-proof material layer, and a step of forming a black filter layer by dyeing the portion of the material layer to be dyed from which the dye-proof material layer is removed to black. Solid-state image sensor manufacturing method. 2. A step of forming a material layer to be dyed on an upper surface of a semiconductor substrate on which a photoelectric conversion element is mounted, and a step of forming a transparent and undyed dye-proof material layer on the upper surface of the material layer to be dyed. A step of removing an unnecessary portion of the dye-proof material layer, a step of forming a black filter layer by dyeing the portion of the dye-dyed material layer from which the dye-proof material layer has been removed black.
And a step of forming a desired color filter layer on the upper surfaces of the dye-proof material layer and the black filter layer. 3. A step of forming a material layer to be dyed on the upper surface of a semiconductor substrate on which a photoelectric conversion element is mounted, and a step of forming a transparent and non-dyed dye-proof material layer on the upper surface of the material layer to be dyed. A step of removing an unnecessary portion of the dye-proof material layer, a step of forming a black filter layer by dyeing the portion of the dye-dyed material layer from which the dye-proof material layer has been removed black.
And a step of forming a microlens on the upper surfaces of the dye-proof material layer and the black filter layer.