JP2007208051A - Solid-state imaging device and manufacturing method thereof - Google Patents

Abstract

An object of the present invention is to reduce the thickness of a color filter layer by increasing the concentration of a dye contained in a color filter layer laminated on a solid-state imaging device.
In stacking a color filter layer of a different color on each of a plurality of photoelectric conversion elements that are two-dimensionally arranged on the surface of a semiconductor substrate, a first color filter is formed on the top of the plurality of photoelectric conversion elements. A solid-state imaging device in which layers are stacked and the first color filter layer on the required photoelectric conversion element among the photoelectric conversion elements is removed by etching, and then the upper portion of the required photoelectric conversion element is filled with the second color filter layer In the method, after removing the dye material residue 22 of the first color filter layer generated by the etching process of the first color filter layer 21, the second color fill layer is laminated. Since the residue 22 does not remain, a large amount of the dye material can be contained in the first color filter layer 21.
[Selection] Figure 2

Description

  The present invention relates to a solid-state imaging device and a manufacturing method thereof, and more particularly to a solid-state imaging device having a color filter layer capable of obtaining good spectral characteristics and a manufacturing method thereof.

  A CMOS or CCD solid-state imaging device used for a digital camera or the like is equipped with a color filter so that a color image can be captured. The color filter is laminated on the surface of a semiconductor substrate in which a large number of photodiodes (photoelectric conversion elements: pixels) are two-dimensionally arranged via a planarization layer. In the case of a primary color solid-state imaging element, A color filter of any one of red (R), green (G), and blue (B) is stacked on each photodiode.

  Hereinafter, a pixel in which a red color filter is stacked is referred to as an R pixel, a pixel in which a green color filter is stacked as a G pixel, and a pixel as a blue color filter is referred to as a B pixel. The R pixel, G pixel, and B pixel are each a semiconductor. Discretely arranged on the substrate surface in a periodic checkered manner.

  In order to stack a color filter of one of R, G, and B for each pixel, for example, a red color filter layer is first formed on the upper surface of the flattening layer as described in Patent Document 1 below. After the lamination, an etching process is performed to remove the red color filter layer above the G pixel and the B pixel.

  Next, a green color filter layer is laminated on the entire surface, and then the surface is flattened by CMP or the like to remove the green color filter layer on the R pixel and fill the G pixel and B pixel with the green color filter layer. . Etching is then performed to remove the green color filter layer on the B pixel.

  Finally, a blue color filter layer is stacked on the entire surface, the B pixel is filled with the blue color filter layer, and the surface of the solid-state imaging device is flattened by CMP or the like, so that the blue color filter layer on the R pixel and G pixel is obtained. Then, a solid-state imaging device for imaging a color image in which a color filter layer of one color is laminated on each pixel is manufactured.

  In recent years, a solid-state imaging device manufactured through such a color filter layer manufacturing process has been increased in number of pixels due to progress of integrated circuit technology, and it has become common to mount several million pixels or more. For this reason, the dimension in the horizontal direction (direction along the surface of the semiconductor substrate) of each pixel is decreasing, and the path of light incident on each pixel is becoming a narrow narrow path.

JP-A-5-183140

  As described above, in the solid-state imaging device that has been increased in the number of pixels, the horizontal dimension of each pixel has been reduced. Therefore, if the color filter layer is manufactured thinly in order to reduce the vertical dimension of each pixel in accordance with the miniaturization, the amount of pigments and dyes contained in the color filter layer is reduced. There arises a problem that spectral characteristics cannot be obtained and red, green, and blue are not sufficiently distinguished.

  However, when the concentration of pigments and dyes to be included in the color filter layer is increased, since the pigments and dyes contain metal elements (Cu, Cr, Ni, Al, etc.), dry etching using oxygen is completely The metal element cannot be removed, leaving a metal residue. In the above example, the etching residue of the red color filter layer remains under the green color filter layer of the G pixel, and the etching residue of the red and green color filter layers remains under the blue color filter layer of the B pixel. End up.

  An object of the present invention is to provide a manufacturing method of a solid-state imaging device that can make a color filter layer thin and obtain sufficient spectral characteristics, and a solid-state imaging device manufactured by this manufacturing method.

  The method for manufacturing a solid-state imaging device according to the present invention includes a plurality of the photoelectric conversion elements when a color filter layer of a different color is stacked on each of the plurality of photoelectric conversion elements that are two-dimensionally arranged on the surface of the semiconductor substrate. A first color filter layer is laminated on the upper surface of the substrate, and the first color filter layer on the required photoelectric conversion element is removed from the photoelectric conversion element by an etching process. In the method of manufacturing a solid-state imaging device that fills the upper part of the first color filter layer, after removing the pigment raw material residue of the first color filter layer generated by the etching process of the first color filter layer, Lamination is performed.

  The coloring material contained in the color filter layer in the method for producing a solid-state imaging device of the present invention is composed of a pigment or a dye.

  The etching process of the method for manufacturing a solid-state imaging device according to the present invention is performed by dry etching using oxygen.

  In the method for manufacturing a solid-state imaging device according to the present invention, the removal of the residue is performed by halogenating the residue remaining in the etching process.

  The removal of the residue in the method for producing a solid-state imaging device according to the present invention is characterized in that the oxide residue of the dye material generated by the dry etching is reduced with a reducing gas and then halogenated.

  The color filter layer of the method for producing a solid-state imaging device of the present invention is characterized in that a non-photosensitive resist is mixed with a pigment or dye of a required color.

  The solid-state imaging device manufacturing method of the present invention is characterized in that the etching treatment and the halogenation treatment are simultaneously performed using a process gas in which oxygen and a halogen-based gas are mixed.

  The method of manufacturing a solid-state imaging device according to the present invention is characterized in that the etching process, the halogenation process, and the reduction process are performed simultaneously using a process gas in which oxygen, a halogen-based gas, and a reducing gas are mixed. .

  In the solid-state imaging device manufacturing method of the present invention, a color filter layer of any one of the three primary colors of red, green, and blue is stacked on the photoelectric conversion elements of the solid-state imaging device, and the first color filter The layer is a color filter layer of any one of the three primary colors, and the second color filter layer is a color filter layer of one of the remaining two colors of the three primary colors.

  The solid-state imaging device of the present invention is a solid-state imaging device including a semiconductor substrate in which a plurality of photoelectric conversion elements are two-dimensionally arranged on the surface portion, and a color filter layer stacked on the semiconductor substrate. A first color filter layer and a second color filter layer manufactured by the method for manufacturing a solid-state imaging device according to any one of the above.

  According to the present invention, since no residue remains, it is possible to contain a sufficient amount of the dye material in the thin color filter layer.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic cross-sectional view of approximately one pixel of the solid-state imaging device according to the first embodiment of the present invention. Although the solid-state image pickup device in the illustrated example is a CCD type, the following embodiments can also be applied to a CMOS type other solid-state image pickup device. Although a solid-state imaging device using a primary color filter will be described, the following embodiments can also be applied when a complementary color filter is used.

  In FIG. 1, in the solid-state imaging device 1 of the present embodiment, a p-well layer 3 is formed on a surface portion of an n-type semiconductor substrate 2, and a pn is formed between the p-well layer 3 and the p-well layer 3. An n region 4 constituting a junction (photodiode: photoelectric conversion element) is formed.

  In the illustrated example, a p region 5 constituting an element isolation region is formed on the right side of the n region 4, and a surface p layer (p-type impurities are diffused at a high concentration) on the surface of the n region 4, continuous to the p region 5. Layer 6). The p well layer 3 is also provided with an n region (buried channel) 7 constituting a vertical charge transfer path.

  A gate insulating film 10 having an ONO (oxide film-nitride film-oxide film) structure is stacked on the outermost surface of the semiconductor substrate 2 on which these regions 3, 4, 5, 6, and 7 are formed. A light shielding film 11 having an opening 11a is laminated on the light receiving surface of the photodiode (n region 4). Under the light shielding film 11, a transfer electrode film (for example, polysilicon film) 12 constituting a vertical charge transfer path is embedded via an insulating layer 13.

  A planarizing layer 15 is laminated on the light shielding film 11, a color filter layer 16 is laminated thereon, and a top microlens 17 is laminated on the top.

  FIG. 2 is a diagram for explaining a main part of the manufacturing process of the color filter layer 16 shown in FIG. First, as shown in FIG. 2A, a color filter layer 21 of the first color (for example, red R) is laminated on the entire light receiving surface of the solid-state imaging device 1 manufactured up to the planarization layer 15 of FIG. In the present embodiment, the color filter layer 21 is configured by mixing a pigment (or dye) 22 serving as a first color pigment material in a non-photosensitive resist having no photosensitive group.

  Then, a photosensitive resist layer 23 is laminated on the entire surface, the resist layer 23 is left on the pixel (photodiode) on which the first color filter layer 21 is laminated, and the second color (for example, green G), the third color. The photosensitive resist layer 23 on the pixel on which the color filter layer (for example, blue B) is stacked is removed by photoetching (state shown in FIG. 2A).

  Next, as shown in FIG. 2B, dry etching of the color filter layer 21 is performed using oxygen gas and the resist layer 23 as a mask. This dry etching is performed until the surface of the planarization layer 15 is exposed. However, the metal element of the pigment 22 contained in the color filter layer 21 remains as an etching residue 22 only by dry etching using this oxygen gas.

  Therefore, next, as shown in FIG. 2C, the metal residue 22 is removed by halogenating the metal element 22 using a halogen-based gas, preferably chromium (Cr) gas or bromine (Br) gas. As a result, as shown in FIG. 2D, the exposed surface of the planarization layer 15 is cleaned.

  Thereafter, similarly, the second color filter layer is laminated and dry etching is performed, the metal residue is removed using a halogen gas, and the third color filter layer is laminated, so that each pixel has three primary colors. A solid-state imaging device in which one of the color filter layers is stacked is manufactured.

(Second Embodiment)
FIG. 3 is a main part process diagram illustrating the color filter manufacturing procedure of the solid-state imaging device according to the second embodiment of the present invention. In the first embodiment, the dry etching process using oxygen gas (FIG. 2B) and the residue removal process using halogen gas (FIG. 2C) are performed separately. When dry etching is performed using oxygen gas, a halogen-based gas is mixed in the process gas in addition to the oxygen gas, and the metal residue is simultaneously halogenated and removed (FIG. 3B). This makes it possible to shorten the manufacturing time of the color filter layer.

(Third embodiment)
FIG. 4 is a process chart of main parts showing a color filter manufacturing procedure of the solid-state imaging device according to the third embodiment of the present invention. The same applies to the second embodiment up to FIGS. 2A and 2B of the second embodiment.

  When the color filter layer 21 is dry-etched with a process gas in which a halogen-based gas is mixed with oxygen gas, the residue 24 may remain on the surface of the planarization layer 15 as shown in FIG. The residue 24 is often an oxide of the metal 22 generated by dry etching with oxygen gas, and is a residue that cannot be completely halogenated.

  Therefore, in this embodiment, as shown in FIG. 4D, dry etching treatment and halogenation treatment are performed with a process gas in which oxygen gas and halogen-based gas are mixed (FIG. 4B). Residue removal treatment is performed with a process gas in which a reducing gas (for example, hydrogen gas) is mixed with a gasification gas.

  In this residue treatment, the metal oxide 24 is reduced by the reducing gas, and the reduced metal element is halogenated by the halogen-based gas and removed. Thereby, as shown in FIG. 4E, the surface of the planarization layer 15 is cleaned.

  The process shown in FIG. 4B may be divided into a dry etching process using oxygen and a halogenation process of a residue using a halogen-based gas. Similarly, the process shown in FIG. It is also possible to separate the oxide reduction treatment using a reducing gas and the residue halogenation treatment using a halogen-based gas.

(Fourth embodiment)
FIG. 5 is a process chart of main parts showing a color filter manufacturing procedure of the solid-state imaging device according to the fourth embodiment of the present invention. In the third embodiment shown in FIG. 4, a process using a process gas in which an oxygen gas and a halogen-based gas are mixed (FIG. 4B) and a process gas using a process gas in which a halogen-based gas and a reducing gas are mixed (FIG. 4). (D)) is performed separately.

  On the other hand, in this embodiment, dry etching, metal element halogenation, and metal oxide reduction are simultaneously performed using a process gas in which an oxygen gas, a halogen-based gas, and a reducing gas are mixed ( FIG. 5B). Thereby, shortening of a manufacturing process can be aimed at.

  According to each of the embodiments described above, the etching process can be performed without leaving a metal residue. Therefore, the color filter layer is mixed with an amount of pigment or dye that can provide sufficient spectral sensitivity characteristics even with a thin color filter layer. It becomes possible.

  The method for producing a solid-state imaging device according to the present invention can etch the color filter layer without leaving a residue of the pigment or dye. Therefore, a thin film of the color filter layer can be obtained by adding a large amount of pigment or dye to the color filter layer. This is useful as a method for manufacturing a color solid-state imaging device to be mounted on a digital camera.

It is a cross-sectional schematic diagram for substantially one pixel of the solid-state imaging device according to the first embodiment of the present invention. FIG. 3 is a main part process diagram illustrating a manufacturing procedure of the color filter layer shown in FIG. It is principal part process drawing which shows the manufacture procedure of the color filter layer which concerns on 2nd Embodiment of this invention. It is principal part process drawing which shows the manufacture procedure of the color filter layer which concerns on 3rd Embodiment of this invention. It is principal part process drawing which shows the manufacture procedure of the color filter layer which concerns on 4th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Solid-state image sensor 2 Semiconductor substrate 15 Planarizing layer 16 Color filter layer 21 Non-photosensitive resist (color filter layer) mixed with pigment (or dye)
22 Pigment (or dye)
23 Photosensitive resist 24 Oxide residue

Claims (10)

  When a color filter layer of a different color is stacked on each of a plurality of photoelectric conversion elements that are two-dimensionally arranged on the surface of a semiconductor substrate, a first color filter layer is stacked on the plurality of photoelectric conversion elements. In the method of manufacturing a solid-state imaging device, the first color filter layer on the required photoelectric conversion element among the photoelectric conversion elements is removed by an etching process, and then the upper portion of the required photoelectric conversion element is filled with the second color filter layer. A solid-state imaging device comprising: stacking the second color fill layer after removing a pigment raw material residue of the first color filter layer generated by the etching process of the first color filter layer Manufacturing method.   The method for manufacturing a solid-state imaging device according to claim 1, wherein the coloring material contained in the color filter layer is composed of a pigment or a dye.   The method for manufacturing a solid-state imaging element according to claim 2, wherein the etching process is performed by dry etching using oxygen.   4. The method for manufacturing a solid-state imaging device according to claim 1, wherein the residue is removed by halogenating the residue remaining in the etching process.   5. The method of manufacturing a solid-state imaging device according to claim 4, wherein the residue is removed by reducing the oxide residue of the dye raw material generated by the dry etching with a reducing gas and then halogenating the oxide residue.   6. The method of manufacturing a solid-state imaging device according to claim 1, wherein the color filter layer is configured by mixing a pigment or dye of a required color in a non-photosensitive resist.   5. The method of manufacturing a solid-state imaging device according to claim 4, wherein the etching process and the halogenation process are simultaneously performed using a process gas in which oxygen and a halogen-based gas are mixed.   6. The manufacturing of a solid-state imaging device according to claim 5, wherein a process gas obtained by mixing oxygen, a halogen-based gas, and a reducing gas is used, and the etching treatment, the halogenation treatment, and the reduction treatment are performed simultaneously. Method.   A color filter layer of any one of the three primary colors of red, green, and blue is laminated on the top of each photoelectric conversion element of the solid-state imaging device, and the first color filter layer is a color of any one of the three primary colors. 9. The solid-state imaging according to claim 1, wherein the second color filter layer is a filter layer and is a color filter layer of one of the remaining two colors of the three primary colors. Device manufacturing method.   10. A solid-state imaging device comprising: a semiconductor substrate in which a plurality of photoelectric conversion elements are arrayed in a two-dimensional manner on a surface portion; and a color filter layer stacked on the semiconductor substrate. A solid-state imaging device comprising a first color filter layer and a second color filter layer manufactured by the method for manufacturing a solid-state imaging device according to claim 1.

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