JPS6382083A - Color solid-state image picture device - Google Patents

Abstract

PURPOSE:To hold two color filters constant in area and to preclude characteristic deterioration such as a color irregularity by providing the two-color filters so that a 1st color filter is at the center part of the opening part of one photoelectric conversion part where at least one couple of opposite sides are parallel to each and a 2nd color filters are opposite each other across the 1st color filter along the opposite sides. CONSTITUTION:The color filter 12 of yellow and color filters 11 and 13 of magenta on both its are arranged at the rectangular photodiode opening part formed having both side 14a and 14b in parallel with each other. The area of the color filter 12 is equal to the total area of the color filters 11 and 13. Further, both color filters are formed a little bit wider than the opening part and even if a mask shift in position, the color filters are securely formed on a photodiode. For example, the filter 12 of yellow shifts in position upward, i.e., in an (x) direction. In this case, the area of the color filter 11 of magenta decrease and the area of the color filter 13 increases, but their total area is unchanged and spectral characteristics do not vary.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a color solid-state imaging device, and is particularly used in an electronic still camera.

(Prior Art) A color solid-state imaging device is equipped with a color filter in a pixel section in which a large number of photodiodes that perform photoelectric conversion of incident light are arranged in a matrix, and extracts signals of three colors in a multiplexed form. The multiplexed signal extracted in this way is converted by a demodulation circuit into three primary color signals or, as will be described later, into signals equivalent to three primary color signals such as a luminance signal and a color difference signal, and a standard television signal is synthesized.

As a color filter, one called a complementary color line sequential type filter is currently used in many products.

Figure i4 shows an example of this, in which a color filter is provided on the photodiode represented by a dotted square in Figure 4(a). In the figure, Ye represents yellow, i.e. green (G), ten red (R), and cy represents cyan, i.e. blue (
B) represents ten green (G), Mg represents magenta or blue (B), ten red (R), and G represents green. Such a pixel section is simultaneously read out in two rows, one above the other, with a shift of one row for each field. This readout method is called a field accumulation method, and the readout result for scanning line 1 is as shown in Figure 5(a), and if this is expressed in three color components, it is as shown in Figure 5(C). If we pay attention to the amount of change, it can be expressed as shown in FIG. 5(e). That is, 2R
-G color difference components are obtained in a modulated form.

Similarly, the scanning result for scanning line 2 shifted by two lines is the fifth one.
The result is as shown in FIG. 5(b), the three color components are shown in FIG. 5(d), and the amount of change is shown in FIG. 5(g). Therefore, 2R-G color difference signals are obtained from the odd-numbered scanning lines, and 2B-G color difference signals are obtained from the even-numbered scanning lines.

Note that if the signals in FIGS. 5(a) and 5(b) are averaged using a low-pass filter, a +3G/2+R luminance signal as shown in FIG. 5(f) is obtained, and any scanning line It can be seen that equal luminance signal components can be obtained even in the case of .

The above operation shifts the read line by one line every 1/60 seconds, and in the odd field, it reads 1, 2, 3, etc.
In even-numbered fields, reading is performed alternately like 1', 2', 3', and so on.

FIG. 6 shows a schematic configuration of a color difference sequential type signal processing circuit. CC that passes through a lens 51, an infrared cut filter 52, a crystal low-pass filter 53, and a color separation filter 54.
It is input to D55. The signal obtained by the CCD 55 is converted into a luminance signal by the LPFh 56 and the processing section 59.
Further, a color difference signal is obtained by the BPF 57 and the detector 60. Further, the color difference signal is obtained by white balancing the COD signal in the white balancer 62 based on the signal obtained by the LPF, 58, and the processing unit 61, and by using the IH switch 64 to delay the COD signal in the delay circuit 63 or not. The signals are mixed and γ-corrected by a mixer 65 via a balanced modulator 66, and an NTSC signal is output. Note that the CCD 55 uses the COD driver 68 based on the signal output from the logic circuit 67.
driven by.

With the field storage method described above, if the optical input is continuous, as in a normal television camera, there will be no audible reading, but if the optical input is continuous, as in an electronic still camera, only a momentary optical input is caused by the shutter. If the camera does not have
Since all the signal charges are read out and disappear when the reading of odd-numbered scanning signals is completed, there is a problem that there is no even-numbered scanning output.

In order to solve this problem, a color filter having a configuration as shown in FIG. 4(b) has been proposed. That is, the photoelectric conversion section of the photosensitive pixel section is divided and provided corresponding to odd and even scanning lines, and 2f-fIl type color filters are formed in each pixel section read out in one field. In such a color homogeneous imaging probe, two adjacent
A complete signal can be obtained by extracting signals every 1/30 seconds for the color filters for rows and reading them as 1, 2, 3, etc. in even fields, 1', 2', 3', etc. in odd fields. An interlaced signal will be obtained. This method is called a frame storage method.

FIG. 7 shows a color filter in a frame accumulation type solid-state imaging device, and shows one photoelectric conversion unit 11 of the imaging device.
It shows how two types of color filters are formed on the top. In FIG. 7, yellow 12 and magenta 13 are formed. These color filters must be formed with high precision so that there are no overlaps or gaps, and the areas of the two color filters are equal. This is because the human eye is extremely sensitive to relative color differences, and the dimensional deviation due to misalignment or inclination of the mask needs to be 5% or less.

However, such high precision is extremely difficult in practice. For example, the photodiode aperture is 8μm x 5μm.
Assuming that, the 5% values are 0.4 .mu.m and 0.25 .mu.m, respectively.The mask alignment accuracy for forming the color filter shown in FIG. 7 is particularly severe in the X direction. Furthermore, in so-called bonded filters in which a color filter formed on a glass plate is fixed onto a silicon chip with an adhesive, it is even more difficult to maintain accuracy due to the instability of the adhesive layer. FIG. 8 shows the color filters 11 and 1 shown in FIG.
(a) represents the desirable spectral characteristics of 2, and (a) is Ye+Mg.
, (b) shows the case of Cy+G, (C) shows the case of Cy+Mg, and (d) shows the case of Ye+G, which require spectral characteristics such that the transmittance changes suddenly at a certain wavelength. If the filter is dyed to have such spectral characteristics, there will be no need to divide within one pixel, but if the spectral characteristics shown in the figure are 50%
It is very difficult to achieve an accuracy of ±5%, and if the accuracy of the filter is not good, characteristic deterioration such as color unevenness will occur.

(Problems to be Solved by the Invention) As described above, in the conventional frame readout type color solid-state imaging device, it is difficult to arrange the color filters with high precision, so the photodiode section is divided into two and each color filter is There is a problem in that the photodiode must be formed on the divided photodiode section.

[Structure of the invention]

(Means for Solving the Problems) According to the present invention, a color solid-state imaging device includes photoelectric conversion units arranged in a matrix and a two-color filter provided in an opening above the photoelectric conversion units. In the two-color filter, a first color filter is placed in the center of an opening in which at least one pair of opposite sides are parallel to each other for one photoelectric conversion unit, and a second color filter is placed between the two color filters along the opposite sides. It is characterized by having the following.

(Function) In the color solid-state imaging device of the present invention, one of the two color filters is formed so as to sandwich the other color filter, so even if the mask alignment position for the color filter is slightly shifted, The areas of the two color filters are kept constant and problems such as color unevenness do not occur.

(Embodiment) FIG. 1 is a plan view showing one embodiment of the present invention, and FIG.
Four two-color filters are shown that achieve the same spectral characteristics as shown in the figure. For example, according to FIG. 3A, a yellow color filter 12 and magenta color filters 11 and 13 are disposed in a rectangular photodiode opening having hair-lined sides 14a and 14b. The area of color filter 12 is equal to the total area of color filters 11 and 13. Furthermore, both color filters are formed to be slightly wider than the opening, so that even if a mask shift occurs, the color filters are reliably formed at -L of the photodiode. Such a configuration is the same for other color filters as well.

Next, the function of such a color filter will be explained.

Suppose that the position of the yellow filter 12 in Fig. m1 (a) is slightly shifted upward, that is, in the X direction. As a result, the ilj product of the magenta color filter 11 is sandwiched, and the color filter 1
Although the area of 3 increases, the total area remains unchanged and the spectral characteristics do not change. Therefore, desired spectral characteristics can be obtained without strictly controlling mask alignment accuracy, and the yield does not decrease.

FIG. 2 shows a second embodiment of the present invention, in which both sides 1
4a and 14b are not perpendicular, but at an angle θ with respect to the base.
and each color filter 11', 12', 13
' forms a parallelogram. In this case as well, even if there is a mask shift of the color filter, the area of the color filter 12' is equal to the total area of the color filters 11' and 12', and the spectral characteristics do not change.

Further, FIG. 3 shows an example in which the opening shape of the photodiode is not necessarily rectangular, and in this case, a notch 15 is provided at the top. In this embodiment as well, since both sides are parallel, there is no change in the spectral characteristics even if the central color filter position is shifted.

In the above embodiments, the areas of the first color filter at the center and the second color filters sandwiching it are equal, but the area is not limited to this, as long as they have a constant area ratio.

Furthermore, the type of color filter shown in FIG. 1 is of course not limited to this, and may be of any color as long as it is used as a color solid-state imaging device.

〔Effect of the invention〕

As described above in detail based on the embodiments, according to the present invention, the second color filter is formed so as to sandwich the first color filter in the opening of the photoelectric conversion section whose opposing sides are parallel. Therefore, even if there is some misalignment of the mask, the spectral characteristics do not change, which not only improves the yield, but also allows the mask alignment accuracy to be moderated and improves productivity.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a color filter structure in a color solid-state imaging device according to the present invention, FIGS. 2 and 3 are plan views showing modified examples of the color filter, and FIG. 4 is a plan view showing a color filter structure in a color solid-state imaging device according to the present invention. A plan view showing the configuration, FIG. 5 is an explanatory diagram showing the result of signal readout using the color solid-state imaging device of FIG. 4, and FIG. 6 is a block diagram showing the configuration of a camera adopting the color difference sequential method. FIG. 7 is a plan view showing how a conventional color filter is formed, and FIG. 8 is a graph showing spectral characteristics of a two-color filter. 11.12.13.11', 12', 1B'...
...Color filter, 14a, 14b...Side side. Applicant's agent Sato - Yubata Figure 1 Figure 2 Figure 3 (α) (b) Figure 4 Figure 5 b' and Figure 6

Claims (1)

[Scope of Claims] 1. In a color solid-state imaging device having photoelectric conversion units arranged in a matrix and a two-color filter provided on the photoelectric conversion unit, the two-color filter has one photoelectric conversion unit. The conversion unit is characterized by comprising a first color filter in the center of an opening having at least one set of parallel opposing sides, and a second color filter sandwiching the first color filter along the opposing sides. Color solid-state imaging device. 2. The opening shape of the photoelectric conversion section is characterized in that the side sides are parallel to each other and the second color filter is disposed above and below the first color filter. color solid-state imaging device. 3. The color solid-state imaging device according to claim 1, wherein the total area of the two second color filters is equal to the area of the first color filter. 4. The color solid-state imaging device according to claim 1, wherein the total area of the two second color filters has a constant ratio to the area of the first color filter. 5. The color solid according to any one of claims 1 to 4, wherein the first and second color filters are each formed wider than the opening of the photoelectric conversion section. Imaging device.