JPS58125973A - Solid-state image pickup element - Google Patents

Abstract

PURPOSE:To improve the optical sensitivity, by providing a transparent matter having condensing function to each photoelectric converting element, and at the same time distributing an opaque matter having the light shielding function between the transparent matters. CONSTITUTION:A condensing transparent film 20 is provided on the surface of an element containing a substrate 10, a photoelectirc converting element 11 and opaque films 14 and 14'. The surface of the film 20 has approximately a projected form and functions as a lens having the condensing function and set corresponding to each element 11. While an opaque matter 21 having the light shielding function is provided on the films 14 and 14' respectively and at the middle of the film 20. In such a constitution, an optical path 22 is refracted on the interface of the film 20 and reflected on the interface of the matter 21, and is led to a photoelectric converting region. With such optical path 22, the area of the photoelectric converting region is substantially increased.

Description

[Detailed description of the invention] The present invention relates to a solid-state image sensor.

The development of solid-state image sensing devices has been strongly promoted against the backdrop of recent rapid developments in semiconductor and integrated circuit technology. In solid-state imaging devices, pixels are scanned electronically, and the pixel arrangement is determined with high precision using photolithographic technology, so it has the advantage that image distortion is less likely to occur when imaging a subject, and the imaging tube It is expected that it will be commercialized as an alternative. If the field of application is limited to television cameras for home VTRs, solid-state image pickup devices that provide a sufficient front-page raw image with a sufficient number of pixels are being put into practical use. However, if a television camera for a station or a television camera is to be used as an information processing terminal, an element with sufficient performance has not yet been developed.

FIG. 15 is a schematic diagram illustrating the structure of a conventional solid-state image sensor, which is called an interline solid-state image sensor. In the figure, for convenience of explanation, an element having (3×3) pixels is shown. In the same figure, lFi
Photoelectric conversion element, 2 is a vertical register, 3 is a horizontal register,
4 is an output circuit, and 5 is an output terminal. Since the interline solid-state image sensor is widely known, details of its operation will be omitted and only an outline will be described. - Signal charges photoelectrically converted in a vertical scanning period (field or frame) are moved in parallel to corresponding positions of the vertical register 2 within a vertical blanking period. In FIG. 1, a transfer gate electrode installed between the photoelectric conversion element 1 and the vertical register 2 to control the movement, a channel stopper to achieve the desired movement, etc. are omitted. The signal charges that have been moved in parallel to the vertical register 2 are sequentially moved downward every -horizontal scanning period. On the other hand, the horizontal register 3 receives and removes signal charges from the vertical register 2 during the horizontal blanking period, and sequentially moves them to the left in FIG. The signal charges reaching the output circuit 4 due to this movement are sequentially converted into voltage signals, and a time-series image signal is outputted via the output terminal 5. Registers 2 and 3 in FIG. 1 are analog shift registers composed of charge-coupled devices or packet relay devices. According to such an operation, the photoelectric conversion element 1 from which all the signal charges have been read out over a -vertical scanning period accumulates an amount of charge corresponding to the amount of incident light.

- The movement of signal charges from the photoelectric conversion element 1 to the vertical register 2 is achieved again at the end of the vertical cycle. In this interline type element, the photoelectric conversion element group and the register group are spatially multiplexed, so the chip area is reduced, and yield improvement and cost reduction can be expected. However, unless an opaque film for light shielding is placed on the register group, the charges generated by the incident light during the period in which the signal charges are moved in the vertical direction (that is, the vertical scanning period) will be transferred to the signal charges. It is known that, as a result, a white line called smear appears on the reproduced image, severely degrading the image quality. For this reason, an opaque film must be arranged over the registers. The opaque film is usually composed of metal electrodes such as aluminum. FIG. 2 shows a structural cross-sectional view of a portion AA' shown in FIG. 1. In the same figure,
For convenience of explanation, only a conceptual structural cross-sectional view is shown, and the dimensions do not necessarily correspond to the actual elements. In the figure, 10 is a semiconductor substrate of a first conductivity type (for example, p-type), and 11 is a semiconductor substrate of a second conductivity type (for example, n-type).
A p-n junction is formed between the photoelectric conversion element 1 and the substrate 10 using a diffusion layer of the type (type), forming the photoelectric conversion element 1. 12 is one transfer electrode constituting the vertical register 2, 13 is the aforementioned transfer gate electrode, 14 and 14' are the opaque films, and 15 is a channel stopper. The transfer electrode 12 and the gate electrode 13 are arranged on the substrate 10 via an insulating film (not shown), and the opaque film 14 and 14' are arranged together with the electrodes 12 and 13 via an insulating film. Channel stopper 15
The signal charge accumulated in the diffusion layer ll is transferred to the gate electrode 1.
The signal charge is provided to move the signal charge in one direction to the bottom of the transfer electrode 12 via the bottom of the transfer electrode 12, and acts as a voltage barrier against the signal charge.

According to the present invention, in an image element in which a large number of photoelectric conversion elements are arranged on a semiconductor substrate having a conductivity type, the spectral characteristics and transmission characteristics provided for each element on the surface of the photoelectric conversion element are , characterized in that a transparent body having a light gathering function that differs for each area where the photoelectric conversion elements are arranged, and an opaque body having a light blocking function are arranged between the transparent bodies provided for each of the elements. A digital image element having the following properties is obtained.

Next, the present invention will be described in detail with reference to examples.

FIG. 3 is a sectional view of one embodiment of the present invention. The same figure is the second
The same numbers as in FIG. 2 indicate the same components. However, for convenience of explanation, some of the constituent elements are deleted from the drawings. In the figure, reference numeral 20 denotes a light-collecting transparent film provided on the surface of the element consisting of the substrate 10, the photoelectric conversion element 11, and the opaque films 14 and 14'. The material of the layer 20 does not matter, but it is preferably a resin that takes into consideration processability, which will be described later. The surface of this film 200 is processed to have a roughly convex shape, and the 20 is shaped like the 11
It acts as a lens having a light condensing function provided correspondingly to each of the lenses. Reference numeral 21 denotes an opaque body having a light shielding function provided on 14° 14', and a plurality of opaque bodies arranged on
0. It will be placed in the middle. The opaque body 21 is made of metal and processed to have a generally convex shape.
It is preferable that light reflection is performed well on the zero surface. An example of increased photosensitivity in this embodiment shown in FIG. 3 is illustrated as incident light beam 22.
The optical path that is guided to the photoelectric conversion region after being refracted at the interface 21 and reflected at the interface 21 is shown. With such an optical path,
It is understood that this example effectively increases the area of the photoelectric conversion region. Next, a specific example of the configuration of this embodiment will be described. The structure including 14.14' shown in FIG. 2 is realized using known techniques.

14. To mechanically protect the 14' surface, typically
An insulating film 16 is provided using OVD technology.

Next, a metal such as aluminum is deposited on the entire surface to cover 14 and 14', and 21 is formed using photolithography and etching techniques. The surface shape of No. 21, that is, the roughly convex shape, can be achieved by using the side etch effect in the etching process, and after being formed into a rectangular shape, the polishing can be performed by an electric field polishing process to form an acute angle where the electric field tends to concentrate. A convex shape may be achieved by taking advantage of the rapid progress at the 14.14' part.Furthermore, after forming a metal such as nickel or aluminum into a rectangular shape by electroless plating only on the upper part of 14.14',
A convex shape may be realized by the electric field polishing process. Further, it is also possible to realize this shape using techniques such as ion etching and dry etching. On the other hand, 21
The opaque body formed in the shape may be mechanically attached to the structure. In such cases, metal bumps for electrical connection, which are used in the field of hybrid integrated circuits or high-density packaging technology, can be used. Furthermore, toner used in zepography technology, microcapsules covered with a metal film, etc. can also be used. Since the material is usually spherical in shape, it can be fixed onto 14.14' using a resin or adhesive. In addition, 21 is 14
' and 16 may be brought into direct contact without intervening the insulating film.

On the other hand, regarding the method for forming 20, a transparent substance such as resin or adhesive is uniformly applied onto the structure including 21,
The shape can be achieved by embossing or the like before it hardens. More specifically, the material of the transparent film 20 dissolved in a solvent is uniformly coated onto the element using a spinner or the like, and is heat-treated and solidified at a desired temperature and atmosphere. Next, using a matrix having a shape opposite to the surface shape of the transparent film 200, press the matrix from above while heating the transparent film 20.@If this heating temperature is set appropriately, the transparent film The shape will be carved into the surface of 20. This method is similar to the manufacturing technology of Fresnel lenses and microprisms, so it is an easy problem for the public engineer. According to this method, also in the upper part of 21,
Although this is reflected in the presence of some of the transparent film, it is not an essential problem. Of course, it is clear that other methods used in the above manufacturing techniques can also be used. According to the embodiment shown in FIG. 3, the light beam incident on the solid-state image sensor area is focused on the photoelectric conversion element 11 even in the area on the opaque film 14, 14', so that the light utilization rate is reduced. Ascends to heaven and achieves an increase in light sensitivity.

FIG. 4 is a sectional view showing another embodiment of the present invention;
The same numbers as in the figures indicate the same components. In the figure, 40 is a light condensing transparent body similar to 20, and 41 is 2
It is an opaque body similar to 1 and forms a structure 42 with 40 and 41. This embodiment is characterized in that, unlike the case shown in FIG. 3, the layer is manufactured separately from the interline solid-state image sensor and is disposed closely or close to the upper part of the opaque films 14 and 14'. There is.

Needless to say, in this method, it is necessary to position and fix the structure opening while aligning the structure onto the element assembled in the package. however,
Since the structure (mainly) can be manufactured in a separate process, there is an advantage that the manufacturing process can be arbitrarily selected without being restricted by the semiconductor manufacturing process.

FIG. 5 is a diagram showing another embodiment of the present invention, and the same numbers as in FIG. 3 indicate the same components.

In the figure, 50 is a light condensing transparent film similar to 20, and 51 is an opaque body. This embodiment is different from the embodiment shown in FIG. 3 in that the spectral sensitivity characteristics of the transparent film 50 are not uniform. That is, different spectral sensitivity characteristics are determined by the transparent film 50 for each element of the photoelectric conversion element 11 arranged at equal intervals within the substrate IO. - For example, the area 52 located at the top of 11 in the figure
The area (2) located to the right of id 52(7) has a characteristic of passing blue, and the area 54 located to the left of 1(e) has a characteristic of passing red. According to this configuration method, color imaging is possible with a single element. In other words, in the embodiment shown in FIG. 5, the color filter of the single-chip color image sensor also has a light condensing function. Even in such an embodiment, it is possible to significantly improve the photosensitivity characteristics of an image sensor having a conventional color filter. Of course, it is also possible to change the structure of the transparent film 50 in the embodiment shown in FIG. 5 as shown in FIG. Although an interline solid-state image sensor is used as an example, it is clear that the present invention is not limited to this and can be widely applied to -dimensional or two-dimensional image sensors and MO8M, 0IDW solid-state image sensors, all of which are covered by this book. shall be covered by the invention. Also, what about the shape of the transparent body for light gathering and the opaque body for light shielding? Although only mineral-dimensional shapes are shown as examples, two-dimensional shapes, that is, pyramid-shaped or inverted conical shapes, are easily recommended, and all of these are also included in the present invention. It is included.

[Brief explanation of the drawing]

FIG. 1 is a conceptual structural plan view of an interline solid-state image sensor, FIG. 2 is a sectional view taken along line AA', and FIGS. 3, 4, and 5 are sectional views of embodiments of the present invention. It is. 1...Photoelectric conversion element, 2...Vertical register, 3...Horizontal register, 4...Output circuit, 5...Output terminal , 10...substrate, 11...diffusion layer, 12...transfer electrode of vertical register, 13...transfer gate electrode,
14,14'... Opaque film, 20,40.50
...transparent body, 21,41.51...opaque body, 222.23...incident light ray. Proxy Patent Attorney Uchihara Uchihara Part 1'$2UjJ $3 Figure 4'$5 Figure

Claims (1)

[Claims] In a solid-state image sensor in which a large number of photoelectric conversion elements are arranged on a semiconductor substrate having one conductivity type, the spectral characteristics and transmission characteristics provided for each element on the surface of the photoelectric conversion element are determined by the arrangement of the photoelectric conversion elements. What is claimed is: 1. A solid-state image sensing device comprising: a transparent body having a light condensing function that differs for each area; and an opaque body having a light blocking function disposed between the transparent body provided for each skeleton element.