JPS6336203A - Solid-state color image pickup element and its production - Google Patents

Abstract

PURPOSE:To enhance the sensitivity of an element by utilizing the steps between light shielding films for determining the positions of picture elements to position color filter layers and underlying picture elements by self-alignment. CONSTITUTION:Plural pieces of the picture elements (photodiodes) 21, 22, 23 are formed to a semiconductor substrate 1 so as to be flush with the substrate surface. The surface of the substrate 1 is coated with an insulating film 50 and the light shielding films 40 are deposited by evaporation of Al, etc. on the substrate surface between the respective picture elements. The color filter layers 301, 302, 303 are formed on the surfaces of the respective picture elements 21, 22, 23 so as to fill the recessed faces between the respective picture elements by the steps between the picture element surface and the surface of the light shielding films. The color filter layers 301, 302, 303 are margined along the end faces of the light shielding layers 40 and are separated from each other by the light shielding films 40 by which the bulging of the ends and the overlapping thereof on each other are prevented.

Description

[Detailed description of the invention]

[Objective of the Invention] (Industrial Application Field) The present invention relates to a solid-state color developing element, which is a color filter formed in a convex state (hereinafter referred to as a color filter). ) and a solid-state image element having a color filter produced by this method. (Prior Art) The configuration of a conventional solid-state cuff-imaging device is shown in FIG. FIG. 3(fi) is a plan view C1 showing that photoelectric conversion cells (hereinafter referred to as pixels) 2 facing the surface of a semiconductor substrate 1 and performing photoelectric conversion are arranged in a square lattice. Between each series, registers (not shown) are arranged to read out the curvature C1 generated in each drawing thread 2 and lζ(ilfl-j Densen. 13B' of this conventional imaging probe. Figure 6 shows the cross-sectional view at
Shown in b). Each pixel 2. 2. 2 is a diode. A color filter layer 31°32.33 for color imaging is formed on each pixel 2, 22.23.
2.2 pixels per pixel. Is there a predetermined effect on the signal output of 23? −jBy becoming
Each component of the three primary colors (red, blue, green) can be extracted. The color filter layers 31, 32, and 33 are usually composed of three to four different colors depending on the film arrangement method. In the following explanation, a color filter composed of three types will be explained as an example. In addition, a light shielding film 4 is formed on each pixel quantum to separate light from each pixel. -i
", 'nitsu ("Reference number 5 is an insulating film. The manufacturing procedure of this imaging probe is shown in Fig. 7;
), first, an insulating film 5 is formed between the pixels of the semiconductor substrate 1 on which both threads (not shown) are to be formed, and a light shielding film 4 is formed thereon. Each pixel is formed between the membranes. Next, after forming an insulating film 5 thereon,
On this insulating film 5, a lens 1-0 with an I-shaped structure forming a color filter is applied. Then, a photomask pattern 7 is transferred onto this lens 1-6. Next, as shown in FIG.
A colored filter layer 31 is formed. Repeat the same process as above (color filter layer 3 for second color and third color).
33 respectively. In this way, a conventional A-wafer color filter not shown in FIG. 6(b) is completed. . (Problems to be Solved by the Invention) Each color filter layer 31, 32, 33 needs to cover the corresponding pixel 2, 2, 23. However, in the conventional manufacturing method described above, the color filter layers 31, 32, and 33 suffer from misalignment with the underlying pattern during patterning, as shown in FIG. 8(a). It may become. That is, for example, the color filter layer 31 that is supposed to cover the pixel 21 may protrude onto the adjacent pixel 22. In this case, the light transmitted to the pixel 22 deviates from the original spectrum of the color filter layer, and color reproducibility deteriorates. Further, in this case, since the sloped end portion of the color filter layer 31 is located above the pixel 21, color unevenness is likely to occur in the light incident on the pixel 21. In order to overcome these disadvantages, the color filter layer 31
, 32. Align the ends of 33 so that they are on the photo-shielding film 4''-.

[I have to. In this case, since the end of the color filter layer is inclined, the accuracy δ of the alignment U between the color filter layer and its base must satisfy the following two conditions (see FIG. 8(b)). a=W'/2+W-L/2>δ...(1
)b=L/2-8-W'/2≧δ...
(2) Here, Δ is the width of the inclined portion, W is the width of the light shielding film, W' is the aperture width of the pixel, and is the width of the color filter layer. The width of the color filter layer determined by these two equations is defined by the following equation. W'+2Δ+2δ≦1−≦W’+2W−26・・・・・・
・(3) In order for this equation to have a solution, −(L has a solution, the alignment accuracy δ
is δ≦W/2−Δ/2 (4)
need to be met. Furthermore, in the conventional manufacturing method, it is easy to avoid misalignment when forming multicolor color filter layers.
An overlapping portion 3S as shown in Figure (a) occurs. When this happens, the surface layer becomes uneven,
Due to the lens effect in this surface layer, the light collection efficiency differs from pixel to pixel, which poses a major constraint on device design. In order to eliminate this overlapping structure, if the distance between the color filter layers is C (see FIG. 9(b)), then C=-W-4
6-2Δ〉0 ・・・・・・・・・(5) is not satisfied and necessary. Therefore, alignment ¥1 degree δ is δ≦W/4−Δ/2 ・・・・・・・・・(
6), and higher alignment accuracy than equation (4) is required. Fig. 10 satisfies the condition of equation (6) above and shows the relationship between the alignment accuracy δ and the light shielding film width W by the inclined portion width Δ−0.
, 0, and 5 (71 m), and the slope side is the area that satisfies the above conditions. 500 x 4 with normal 1/2 inch optics. In the OO pixel area range, W-3 is a typical value.
[μm], W'-7 [μm], Δ-0.5 (μm), and from Fig. 10, the required <"C position ♂ 1 combination l accuracy δ is 0.
5 [μm] or less, and it can be seen that highly accurate positioning is required within the range. On the other hand, if the width W of the light shielding film is determined manually, the alignment U precision δ will be low, but this will result in a low level of black stone, making it difficult to increase the number of pixels. In addition, there is a method of combining color filters, but this method makes the above problem worse and is not a solution.The present invention expands the alignment margin between the color filter layer and the underlying pixels. It is an object of the present invention to provide a method for manufacturing a solid-state color image sensor suitable for increasing the number of pixels, and a solid-state curry image sensor manufactured by this method. [Structure of the Invention] (Means for solving the problems) The present invention forms a light-shielding film on the surface of a semiconductor base between a plurality of photoelectric conversion cells (pixels) formed facing the surface of the semiconductor base, and the light-shielding film and this light-shielding film. A layer of a predetermined material forming a color filter is formed on the surface of the region including each pixel, and the predetermined material layer on the surface of the light distribution shielding film is removed by etching. , As a result, the specified material 1'1 on the surface of each pixel remaining
The present invention provides a method for manufacturing a solid-state image carrier in which the layer is dyed to form a color filter layer. However, the present invention is applied to a semiconductor substrate on its surface!
A photoreflective film is formed on the substrate surface between each pixel, and a photoreflective film is formed on the surface of each pixel to fill in the recesses caused by the difference in level between the pixel surface and the photoreflective film surface. The present invention provides a solid-state color imaging element having a color filter layer. (Function) At the stage when a photoresist film is formed on the substrate surface between each pixel,
A step structure is formed on the surface of the substrate, in which the light shielding film is a convex portion and each pixel surrounded by the convex portion is a concave portion. Therefore, the layer (for example, resist) of a predetermined monthly rate (for example, resist) for forming the color filter, which is formed in the 1)
It is thinner on the membrane and thicker on the pixel. Next, the thin layer on the photoresist crotch is removed by etching. This removal leaves an empty layer 4J filling the concave portions of each pixel, and by dyeing this, a color filter layer is formed. This J: Utilizing the stepped structure of the photoresist film formed on the base surface 1co, cell 7? Since the color filter layer is automatically positioned using lines, the problem of misalignment that occurs in the prior art does not occur. (Example) The present invention will be explained below with reference to Examples. FIG. 1 is a cross-sectional structural diagram of an M-8 embodiment of a solid-state color image sensor according to the present invention. In the same figure, the semiconductor N-board 1 has a surface facing the substrate surface, as in the conventional example shown in FIG.
゛Multiple pixels (]A1~Die A-D) 21.22.2
3 is formed. The surface of the substrate 10 is covered with an insulating film 50, and a photoresist film (usually,
A1 vaporized film) 40 is formed on the surface of each pixel 2, 22, and 23, and a color filter layer is formed on the surface of each pixel 2, 22, and 23 so as to fill the recesses of each pixel located at the step between the pixel surface and the light blocking film surface. 30
1.302.303 are formed. In such a structure, each color filter layer 30, 302, 303tj;
) The ends of η are defined by the η1: plane of the diaphragm 40,
In addition, since the phase η is separated by the light shielding film 40, the ends of the sea urchin (J) and the sea urchin (19) of the conventional example do not protrude or overlap with the phase H. Figures 2(a) to 2(d) show an example of the method for manufacturing such a solid color decoy image element. First, as shown in FIG. 5A, the surface of the substrate 1 is coated with an insulating film 50, and then light is applied to the surface of the substrate between the pixels to create an IQ similar to that of the color filter layer to be formed later. A light shielding film 40 is formed. This light shielding film 40 is usually formed by Δ1 vapor deposition. As a result, the light shielding film 40 is formed on the substrate surface.
The IO is a convex part, and each pixel surrounded by this is a concave part, forming a 4M structure with a four-dimensional step. Next, on top of this (on the entire root surface, 1 nozzle 1 to 61 layers for forming a color filter layer)
Paint it II. This resist layer (51 is thin in the photoresist film 4-1-, corresponding to the step structure on the substrate surface
It becomes thicker between the light blocking films (on the pixels). Next, the resist layer 30 on the photoresist film 4' is removed by etching. For example, the method is as follows:
By further adding the structure in Figure (a) to 02 Brazen,
There is a method of backing the lens h Fm 61 by one point from its surface. As shown in FIG. 7N), only the layers 1 to 61 that fill the concave portions of each pixel surrounded by the light blocking film 4 are left behind. Next, only the resist layer 611 on the pixel on which the first color filter layer is to be formed is exposed and developed, and the lenses 1 to ff161, 613 on the other pixels are removed and covered. The remaining resist VA6'11 is subjected to the first dyeing process [1] to form a color filter Ii';'i 301 of the first color C1. Next, as shown in FIG. 2(C), layers 1 to 62 for forming the second color filter layer are applied.
- The photoresist film/IO was etched back in the same manner as described above.
, J- and the first color filter layer 301 except for the resist 1 layer 62. Next, the same exposure as described above.]
1. ! By IW, the second color filter - f'J
The resist layer 623 on other pixels is removed, leaving the layers 1 to 622 L'j on the exposed pixel. Next, as shown in 71>1(d), the remaining lenses 1 to 622 are dyed a second time to form a color filter straddle 302 of the second color 1. At this time, the first color [for the first color filter layer 301, the second color 1]
A predetermined fixation treatment is performed in advance so that the staining is carried out. Thereafter, the color filter layer 303 of the third color is formed in the same manner.
Ru. In this way, the structure shown in FIG. 1 is completed. FIG. 3 is a diagram showing another embodiment of the manufacturing method according to the present invention. This figure shows another method 7'j of the steps shown in FIG. ] - Form the film 80 and partially pattern it to expose the resist layer 611 to form the color filter layer of the first color 1]. Then, this resist layer 611 is dyed to form a first color filter layer 301. Next, the small resist film 80 is removed and a second attenuated bottom resist film is formed.
The resist layer 612 on which the colored filter layer is to be formed is patterned so that it is exposed by +11"J, and the second dyeing is performed. Thereafter, the resist layer 613 is also dyed in the same manner as shown in FIG. As shown in these embodiments, the ends of the color filter layer are attached to the self-alignment line on the end face of the light shielding film that determines the underlying pixel area. '' (defined automatically. Therefore, the alignment accuracy during color filter layer formation is greatly improved.Hereinafter, it will be explained in comparison with the alignment accuracy of the conventional example shown in FIG. 6. The factor that determines the alignment accuracy δ of the color filter layer in the unexploded IIJ is the accuracy of the exposure for defining the 7711-region of each stain. In order to make the exposure light pattern 9 irradiate only the area of a specific pixel 2, the end of the light pattern 9 may be placed on the light shielding film 40.The conditions are as follows. δ〈W/2・・・・・・・・・(7).The relationship between the light shielding film width W and the alignment precision j decay δ according to the present invention determined by this equation (7) is Fig. 5 shows a comparison with the relationship determined by the conventional equation (6).Here, the solid line is the present invention, the broken line is the conventional example, and the diagonal line is the area where the condition is satisfied. The width of the inclined portion Δ is O (μm). As can be seen from the figure, in the present invention, the width W of the optical shield film for the same alignment precision δ is less than half that of the conventional one. This also means that the alignment margin is more than doubled, which is a great advantage in terms of design and manufacturing when increasing the number of pixels. (Effect of the invention ) As explained above, according to the present invention, the 11°V alignment μ between the color filter layer and the underlying pixel is performed by self-alignment using the step of the light shielding film that determines the pixel position. In this way, the alignment margin is expanded, which greatly contributes to higher electric shock and higher pixel counts in devices.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of one embodiment of the solid color hA image according to the present invention, and FIG. 2 is a solid color 11 according to the present invention.
FIG. Figure q and Figure 4 are diagrams explaining the exposure position l according to the manufacturing method of the present invention, and Figure 5 shows the relationship between position 1 viscosity and photoresistance film width according to the method of the present invention and the conventional method. For comparison, Fig. 6 shows the planar structure and cross-sectional structure of a conventional solid-state color imaging device, and Fig. 7 shows a conventional method for manufacturing a solid-state color imaging device. FIG. 8 is a diagram illustrating the positional U misalignment of the color-filter layer in the conventional manufacturing method.
Figure 9 is a diagram explaining the overlap of color filters)+7+ by the same conventional method, and Figure 10 is a diagram explaining the overlap of color filters by the same conventional method
Figure 1 shows the relationship between alignment accuracy and photoresistance film width.
, 30... color filter layer, 40... light blocking film,
61゜62.63...Regime 1 to layer, 80...Ho 1
~Regis 1~Membrane. Applicant's agent Sato - Tsuki 1 3 Illustration 4 Illustration 6 Illustration W [74m] (0) (b) Chi
8 Figure (0) (b) Color 9
Figure δ [PmJ W[PmJ Chi10 Figure

Claims (1)

[Claims] 1. A light-shielding film for optically separating the photoelectric conversion cells is formed on the surface of the substrate between a plurality of photoelectric conversion cells formed in a semiconductor substrate facing the surface thereof. A layer of a predetermined material for forming a color filter layer is formed on the surface of this light shielding film and a region including each photoelectric conversion cell formed between the light shielding films, and a layer of a prescribed material for forming a color filter layer is formed on the surface of the light shielding film. A method for manufacturing a solid-state color imaging device, which comprises removing the material layer by etching, and dyeing the predetermined material layer on the surface of each remaining photoelectric conversion cell to form a color filter layer corresponding to each photoelectric conversion cell. 2. A plurality of photoelectric conversion cells formed in a semiconductor substrate facing the surface thereof, a light shielding film formed on the surface of the substrate between each photoelectric conversion cell for optically separating the photoelectric conversion cells, and each A solid-state color imaging device having a color filter layer formed on the surface of a photoelectric conversion cell so as to fill a recess created by a step difference between the cell surface and the light shielding film surface.