JPS61285755A - Photoelectric conversion device - Google Patents

Abstract

PURPOSE:To shorten sampling time, to reduce the effect of the intensity of incident light on a stop mechanism and to simplify a control circuit, by separately providing a photoelectric conversion element in addition to an optical sensor part in the same substrate of the optical sensor, as a generator of direct and indirect control signals to the optical sensor part. CONSTITUTION:In a photoelectric conversion device 1, the following parts are formed: an oxide film capacitor 4 comprising an N-type diffused layer 2 and a polycrystalline silicon electrode 3; and a P-N junction diode 7 comprising a P-type diffused layer 5 and an N-type diffused layer 6. The P-N junction diode 7 is used as a photodiode. A power source Vcc is connected to the P-N junction diode 7 through an oxide film capacitor 8. When reverse bias is applied to the power source and light (a) is projected, the potential at the P-N junction part of the P-N junction diode 7 is changed. A depletion layer having a specified width is formed so as to hold electrons and holes. The width of the depletion layer is changed by the amount of the incident light. The P-type diffused layer 5 of the P-N junction diode and a P-well diffused layer 9 for an MOS peripheral circuit for driving an optical sensor part are simultaneously formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a photoelectric conversion device, and particularly to a photoelectric conversion device equipped with an optical sensor section for automatic aperture of a TV right camera Sv left camera.

[Prior Art J Conventionally, TVs using image sensors such as COD and MOS
There is a right camera Sv and a left camera that have an auto aperture function. Examples of photoelectric conversion devices equipped with a TV right camera Sv left camera having such an auto aperture function are shown in FIGS. 5 and 6.

Figure 5 is published in Japanese Patent Application Laid-open No. 80-12759 to 1983-
6 is a plan view of the photoelectric conversion device described in Japanese Patent No. 12785, and FIG. 6 is a sectional view taken along the line -■ in FIG. 5.

In both figures, a photosensor section is provided on an n+ silicon substrate 101, and the sensor section is made up of a plurality of photosensor cells. This optical sensor cell is 5i02,
It is electrically insulated from adjacent photosensor cells by an element isolation region 102 made of Si3N4, polysilicon, or the like.

In these optical sensor cells, a p-type impurity is doped onto an n'''' region 103 with a low impurity concentration formed by epitaxial technology or the like to form a p-type region 104.
Further, an n+ region 105 is formed in the p region 104 by impurity diffusion or ion implantation technique. p region +04 and n
The bridge 105 corresponds to the base and emitter of a bipolar transistor.

Further, an oxide film 106 is formed on the n- region 103, and a capacitor electrode 10 having a predetermined area is formed on the oxide film 106.
form 7. This capacitor electrode 107 has an oxide film 1
Since the p regions 104 are arranged to face each other with 0B in between, when a pulse voltage is applied to the capacitor electrode 107, the potential of the p region 104 in a floating state can be controlled.

In addition, the optical sensor cell includes an emitter electrode 108 connected to the n+ region 105, a wiring 108 for reading out a signal from the emitter electrode 108, and a wiring 110 connected to the capacitor electrode 107. An n medium region 111 with a high impurity concentration and an electrode 112 for applying voltage to the collector of the bipolar transistor are provided on the back surface of the substrate 101.

Next, the operation of a conventional photoelectric conversion device including an optical sensor section will be described.

Light 113 enters the p-region 104, which is the base of the bipolar transistor, and a charge corresponding to the amount of light is accumulated in the p-region 104 (accumulation operation).The base voltage changes due to this accumulated charge, and the voltage change is reflected in the floating By reading from the emitter electrode 108 in the state, an electric signal corresponding to the amount of incident light can be obtained (reading operation).

In addition, in order to remove the charges accumulated in the p region 104,
This is performed by grounding the emitter electrode 108 and applying a pulse of positive voltage to the capacitor electrode 107 (refresh operation). In other words, when a positive voltage is applied to the capacitor electrode 107, the p region 1G4 is connected to the n+ region 105. It is forward biased and the accumulated charge is removed.

Thereafter, the operations of storage, readout, and refresh are repeated. That is, in this photoelectric conversion device, charges generated by light incidence are accumulated in the p-region 104, which is the base, and the amount of accumulated charges is applied to the emitter electrode 108.
The current flowing between the collector electrode 112 and the collector electrode 112 is controlled.

The charges accumulated in this way are amplified by the optical sensor's amplification function and then read out, so it is possible to qualitatively improve the photoelectric change detection ability, that is, to achieve high output, high sensitivity, and low noise. It has become.

In a photoelectric conversion device, when particularly strong light enters the optical sensor section, the base voltage gradually increases due to the accumulation of holes generated in accordance with the intensity of the incident light.

In addition, since a forward bias is applied between the base and emitter at this time, the emitter voltage increases and the so-called blooming phenomenon occurs, in which the readout voltage V is output even though it is not applied. be.

For this reason, various attempts have been made to automatically adjust the amount of exposure that enters the optical sensor section.

One such attempt was to push out excess carriers through an overflow drain provided independently of the output circuit to prevent blooming.
This method is particularly effective when locally strong light is irradiated.

In addition to this, there are also devices that have an external device for adjusting the amount of light. In this method, the light amount adjusting diaphragm mechanism can be controlled in accordance with the converted output generated from the surface of the optical sensor section.

Therefore, both methods are used in combination to automatically adjust the amount of exposure that enters the optical sensor section.

[Problems to be Solved by the Invention] However, when adjusting the exposure amount using the latter method described above, the photoelectric change detection power is adjusted in units of at least one pixel (one photosensor cell) of the photosensor section. The aperture value of the light amount adjustment aperture mechanism is determined based on the integral value or the output value per pixel.

For this reason, if an extremely bright area is included in the area to be sampled, the aperture value may shift by that amount.

Therefore, in order to alleviate this phenomenon, a method of widening the sampling area as much as possible has been adopted, but this increases sampling time and becomes inconvenient.

In addition, when the entire surface of the optical sensor section is to be sampled, the sampling time corresponds to the scanning time required to operate the optical sensor section, so if the intensity of the incident light becomes extremely high, the aperture mechanism will not be able to control the diaphragm sufficiently. The problem is that it can't be done.

Further, additional circuits such as a sampling circuit for sampling the optical sensor section or the optical sensor cell, and an arithmetic circuit for calculating the integral value of the photoelectric change detection force value are required. For this reason, it is not possible to meet the demand for simplifying and downsizing photoelectric conversion devices.

The present invention has been made in view of the above circumstances, and it is possible to shorten the sampling time by extracting the output signal from a separate photoelectric conversion element provided on the same board as a generator for generating direct and indirect control signals for the optical sensor section. The purpose of this invention is to reduce the influence of the intensity of incident light on the diaphragm mechanism, and to simplify the control circuit required by the conventional optical sensor section.

[Means for Solving the Problems] The present invention has been made to solve the above problems, and includes a photoelectric conversion device including an automatic aperture photosensor section formed on a semiconductor substrate. The present invention is characterized in that, as a generator of direct and indirect control signals to the optical sensor section, a photoelectric conversion element is provided separately from the optical sensor section within the same substrate as the optical sensor section.

[Function] The present invention uses the above-mentioned means to extract signals for direct and indirect suppression to the optical sensor section from the output signals of separate photoelectric conversion elements in the optical sensor section provided in the same substrate, thereby shortening the sampling time. Furthermore, it reduces the influence of the intensity of incident light on the diaphragm mechanism, and contributes to the simplification of the control circuit and miniaturization of the device, which were required in the conventional optical sensor section.

[Example] Hereinafter, an example of the present invention will be described in detail based on the accompanying drawings. 1 to 4 show an embodiment of the photoelectric conversion device of the present invention.

FIG. 1 is a cross-sectional view of the photoelectric conversion device in this example,
FIG. 2 is a schematic diagram showing the principle of photoelectric conversion.

In the figure, l is a photoelectric conversion device, and this photoelectric conversion device 1
An oxide film capacitor 4 consisting of an n-type diffusion layer 2 and a polycrystalline silicon electrode 3, and a pn junction diode 7 consisting of a p-type diffusion layer 5 and an n-type diffusion layer 6 are formed. This pn junction diode 7 is used as a photodiode.

Further, as shown in FIG. 2, the power supply Vcc is connected to a pn junction diode 7 via an oxide film capacitor 8. When a reverse bias is applied to the power source and light is irradiated, the potential at the pn junction of the pn junction diode 7 changes, forming a depletion layer with a predetermined width between electrons and holes.

The width of this depletion layer changes depending on the amount of incident light.

Further, the p-type diffusion layer 5 of the p-n junction diode 7 is formed at the same time as the p-well diffusion layer 9 for the MO3 peripheral circuit for driving the optical sensor section. This p-type diffusion layer 5 has a high concentration diffusion layer lO for ohmic contact and a p-type diffusion layer 10 for ohmic contact with the p-well diffusion layer 9.
Formed at the same time as the mold cavity concentration diffusion layer.

An n-type diffusion layer 2 is formed under the oxide film capacitor 11, and this n-type diffusion layer 2 is simultaneously formed under the oxide film capacitor 12 inside the shift register. Further, the n-type diffusion layer 6 is an N-channel type MOS transistor 1.
4 sauce 15. It is formed simultaneously with the drain 16. This MOS) transistor 14 is used as a switching transistor.

A polycrystalline silicon electrode is provided as the upper electrode of the oxide film capacitor 4, and this is the same as the polycrystalline silicon electrode that is also provided as the upper electrode of the voltage control capacitor in the base region 17a of the photosensor cell 17 for photoelectric conversion. Formed at the same time as 18.

Note that 13' is an emitter region.

In this way, the photoelectric conversion device in this example can be formed on the same substrate without any change in the manufacturing process of conventional photoelectric conversion devices, making it possible to achieve high integration of the photoelectric conversion section and to reduce costs. It is possible to realize price reduction.

Furthermore, in this embodiment, the photoelectric conversion element 23 produced in this manner is arranged around the optical sensor section 20, the output signal from the photoelectric conversion element 23 is amplified, and the aperture mechanism is directly driven by the output. There is.

By operating the drive mechanism in this manner, the illuminance of light incident on the optical sensor section 20 is controlled.

3 and 4 are layout diagrams of the photoelectric conversion device. The optical sensor section 20 constitutes a light receiving section for image information, and a vertical shift register 21 is provided above the optical sensor section 20.
is arranged, and a horizontal shift register 22 is arranged on the side of the optical sensor section 20. and optical sensor section 2
0 is vertical shift register 21 and horizontal shift register 2
2 in the vertical or horizontal direction to output a photoelectric conversion output.

In this embodiment, as shown in FIG.
A plurality of photoelectric conversion elements 23, for example, four photoelectric conversion elements 23, can be arranged around the photoelectric conversion unit 20 so that a control signal for the photoelectric conversion unit 20 can be obtained.

In this way, the area occupied by the photoelectric conversion element 23 can be made relatively small using the minimum necessary number of photoelectric conversion elements 23, and accordingly, the photoelectric conversion device 1 can be downsized.

Further, as shown in FIG. 4, it is also possible to arrange a photoelectric conversion element 24 between the optical sensor section 20 and the shift registers 21 and 22. In this case, the difference in optical information between the photosensor section 20 and the photoelectric conversion element 24 becomes smaller, so that a more appropriate amount of exposure can be obtained.

[Effects of the Invention] As described above, as a generator of direct and indirect control signals for the optical sensor section, a photoelectric conversion element is provided separately from the optical sensor section on the same substrate as the optical sensor section. By extracting the direct and indirect control signals for the sensor section from the output signals of separate photoelectric conversion elements provided on the same board, the sampling time is shortened and the influence of the intensity of the incident light on the aperture mechanism is reduced. At the same time, the control circuit required by the conventional optical sensor section can be simplified, and the device can be made smaller. Further, since the photoelectric conversion device can be formed on the same substrate without any change in the manufacturing process of the conventional photoelectric conversion device, it is possible to achieve high integration of the photoelectric conversion unit and to reduce the cost.

[Brief explanation of drawings]

Figure 1 is an enlarged sectional view of the photoelectric conversion device, Figure 2 is a schematic diagram of the photoelectric conversion device, Figures 3 and 4 are layout diagrams of the photoelectric conversion device, and Figure 5 is a plan view of the photoelectric conversion device. FIG. 6 is a sectional view taken along the line ■-■ in FIG. Explanation of the symbols 1 is the photoelectric conversion device, 20 is the optical sensor section, 23 is the patent attorney representing the photoelectric conversion element.

Claims (1)

[Claims] In a photoelectric conversion device equipped with an optical sensor section for automatic aperture formed on a semiconductor substrate, direct contact with the optical sensor section,
A photoelectric conversion device comprising, as a generator of an indirect control signal, a photoelectric conversion element separate from the optical sensor section within the same substrate as the optical sensor section.