JP2556856B2 - Color solid-state image sensor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a color filter for a color solid-state image pickup element formed on an image pickup substrate having a semiconductor structure in which a plurality of optical sensor sections are arranged.

<Prior Art> A so-called on-wafer color filter forming technique for directly forming a color filter on a semiconductor substrate on which a solid-state image sensor is formed is carried out as shown in FIGS. 2 (a) and 2 (b). That is, as shown in FIG. 2A, the transparent resist 3 is applied onto the wafer 1 for which the wafer process of the image pickup device 2 is completed, and the unevenness of the element 2 is flattened and the adhesion of the dyeable resist is improved. After that, a dyeable photoresist serving as a filter portion is applied, exposed and developed to form a dyeable photoresist pattern on predetermined pixels.

Then, the wafer 1 is immersed in the first dyeing solution to dye the photoresist pattern to be dyed to form the first colored filter 4.

After the wafer 1 on which the first colored filter 4 is formed is dried, the transparent resist 5 is applied on the wafer 1 as shown in FIG. Next, a photoresist pattern to be dyed is newly formed on the transparent resist 5, and the second coloring filter 6 is formed by using the second dyeing solution. Then, a transparent resist 7 is applied on the wafer 1 on which the second colored filter 6 is formed, and a third colored filter 8 is formed by using a dyeable photoresist in the same manner as in the above step, and the uppermost layer is transparently protected. Form the film 99. The transparent resists 5 and 7 between the colored filters 4, 6 and 8 are formed to prevent color mixing between the colored filters 4, 6 and 8 and play a role as a stainproof film.

<Problems to be Solved by the Invention> The number of stacked color filters of the color solid-state imaging device formed as described above varies depending on the color to be transmitted. For example,
When cyan and yellow colored filters are laminated to form a two-layered colored filter for transmitting green,
Since the layer coloring filter has a larger curvature than other single layer coloring filters, the lens effect of the two-layer coloring filter is larger than that of the single layer coloring filter, and the lens effect is unbalanced as a whole of the color solid-state imaging device. Therefore, there is a problem that the S / N ratio of the color signal decreases.

<Means for Solving Problems> The present invention has been made to solve the above-mentioned problems, and a plurality of solid-state imaging devices are formed on one main surface of a semiconductor substrate, and In a color solid-state imaging device having a single-layer or multi-layer color filter formed therein, transparent filters are laminated on the single-layer or multi-layer color filters so that the number of layers is the same as the maximum number of the color filters. And a color solid-state image pickup device.

<Operation> As described above, by making the number of filter layers laminated on all the solid-state imaging devices the same, the curvature of the colored filter layer having a smaller number of laminated layers has been changed to the curvature of the colored filter layer having a larger number of laminated layers in the past. The phenomenon that the size becomes smaller than that of the solid-state image pickup device is eliminated, and the curvature of the filter layer on the solid-state image pickup device can be unified, and at the same time, the sensitivity of the brightness of the entire color solid-state image pickup device can be increased.

<Examples> Examples of the present invention will be described below with reference to the drawings, but the present invention is not limited thereto.

1 (a) to 1 (c) are sectional views showing a manufacturing process of an embodiment of the present invention. First, as shown in FIG. 1 (a), a solid-state image sensor 2 is formed on one main surface of a wafer 1, and a transparent resist 3 is applied on the main surface of the wafer 1 to flatten the unevenness on the solid-state image sensor 2. And further improve the adhesion with the dyeable photoresist used in the next step. Next, a dyeable photoresist is applied on the transparent resist 3 and exposed.
Development is performed to form dyeable photo-esthetic patterns on predetermined image pickup devices 2a and 2c. Then, the wafer 1 is immersed in a first dyeing solution to dye the photoresist pattern to be dyed to form a first colored filter 4.

Next, the wafer 1 on which the first colored filter 4 is formed is dried, and then a transparent resist, which is a stain-proof film 5 for preventing color mixing of the colored filter, is applied on the wafer 1 as shown in FIG. 1B. . A dyeable photoresist pattern is newly formed on the predetermined image pickup element 2d of the dye-proof film 5, and the dyeable photoresist pattern is dyed with a second dyeing solution to form a second colored filter 6. . The dye-proof film 7 is formed on the wafer 1 on which the second color filter 6 is formed, and the third color filter 8 is formed on the predetermined image pickup devices 2b and 2c of the dye-proof film 7 in the same manner as described above. .

Next, as shown in FIG. 1C, a stain-proof film 10 is newly formed on the wafer 1 including the third colored filter 8, and the stain-proof film 10 is formed.
A transparent resist is applied onto the dye-proof film 7 or above and exposed and developed to form a transparent resist pattern on the solid-state imaging devices 2a, 2b, 2d having a single-layer color filter. Is a transparent filter 11. A transparent protective film 12 is formed on the wafer 1 on which the transparent filter 11 is formed to complete a color solid-state imaging device.

In this way, by making the number of filters laminated on all the solid-state image pickup devices the same, the curvature of the filter layers is unified over all the solid-state image pickup devices.

<Effects of the Invention> According to the present invention, the number of filter stacks on all solid-state image sensors forming a color solid-state image sensor is the same as the maximum number of color filter stacks, and the curvature of the filter layers is increased and unified. As a whole, the color solid-state image pickup device has improved sensitivity of luminance, the lens effect of the filter layer is improved in a balanced manner, and the S / N ratio of the color signal is increased as compared with the conventional one. Therefore, the present invention contributes to the manufacture of a color solid-state image pickup device having high accuracy and sensitivity.

[Brief description of drawings]

1 (a) to 1 (c) are sectional views showing a manufacturing process of an embodiment of the present invention, and FIGS. 2 (a) and 2 (b) are sectional views showing a manufacturing process of a conventional example. 1: Wafer, 2.2a, 2b, 2c, 2d solid-state image sensor, 3 ... Transparent resist, 4 ... First colored filter, 5.7.10 ... Dye-proof film, 6 ... Second colored filter, 8 ... … Third colored filter, 9.12 …… Transparent protective film, 11 …… Transparent filter

Claims (1)

(57) [Claims] 1. A color solid-state imaging device comprising a plurality of solid-state imaging devices formed on one main surface of a semiconductor substrate, and a single layer or a plurality of layers of colored filters laminated on the solid-state imaging devices, respectively. In a color solid-state image pickup device in which the number of layers of the colored filter is different between solid-state image pickup devices, a predetermined number of transparent filters are laminated on each single-layer or plural-layered colored filters on each solid-state image pickup device to form a solid-state image sensor. A color solid-state image sensor, wherein the number of filter layers on the image sensor is the same as the maximum number of layers of the colored filter.