JPS6374275A - Solid-state image pickup device - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a solid-state mechanical device that integrates a photoelectric conversion element and a scanning circuit on a semiconductor substrate and sequentially reads out optical information. [Summary of the invention] Is the invention applicable to television cameras, etc.? In the solid-state imaging device, the performance of the % imaging is improved by eliminating noise in the solid-state imaging device as described in the first section. [Prior Art] An overview of the conventional technology will be explained using FIGS. 3 and 4. FIG. 3 shows the configuration of a two-dimensional solid-state imaging device. A photodiode 1 is used as a photoelectric conversion element, and the original diodes 1 are arranged in a matrix. For example, the switch MO8 transistors 2 and 3 select the photodiode 1, and the MOS transistors 2 and 3 are controlled by a vertical scanning circuit 9 and a horizontal scanning circuit 10, respectively, through a vertical scanning gate 4 and a horizontal scanning gate 5. . That is, the optical information of the photodiode 1 selected by the vertical scanning circuit 9 is transmitted to the vertical signal line 6 by the switching MO8.
) Primary horizontal scanning circuit i read out through transistor 2. The transistor 3 for the switch selected by MO8) reads out the optical information on the vertical signal line 6 to the horizontal signal line 7, and outputs the optical information to the output terminal 8. Photodiodes arranged in a matrix like this
By sequentially selecting and scanning the information accumulated in
This is taken out as a painter's signal. Switch MOB) transistors 2 and 3 or vertical scanning gate 4. Horizontal running gate 5 or vertical signal line 6. Horizontal signal line7. There may be a plurality of output terminals 8 depending on the purpose. Figure 4 shows the cross-sectional structure of a unit pixel of a photoelectric conversion section (for convenience of explanation below): An N-channel type imaging device that uses S electrons as signal charges will be described, but r
The following explanation can be similarly applied to a channel type imaging device by simply reversing the polarity and conductivity type. The unit pixel consists of an SZ substrate 14 made of P-type S<single crystal and n
A photodiode formed of a type diffusion layer 11. It is formed of a MOB type field effect transistor having an n-type diffusion layer 11 formed at the same time as a source, a gate electrode 13 made of multi-connection &87, and an R-type diffusion layer 12 as a drain. Drain 12 is AL! ' is connected to the electrode 15 made of metal to form the vertical signal line 6 shown in FIG. When the light 17 is incident on the iron sensing surface, electron-hole pairs are generated within the n-type diffusion layer 11 and the P-type Si substrate 14. Among them, electrons are injected into the n-type diffusion layer 11 as signal charges, and the n-type diffusion layer 11 and the P-type sz? li! : Accumulated by the junction capacitance formed by the plate 14. When a positive pulse is applied to the vertical scanning gate (vertical scanning gate) 13, a positive potential is applied to the n-type diffusion layer 12 (drain), and electrons, that is, signal charges are distributed to the electrode 15 (vertical signal line 6 in FIG. 3). ), and the third
As explained in the figure, up to the output terminal 8 is read out. At this time, the n-type diffusion layer 11 (source) has a positive potential and continues to accumulate electrons generated by the light 17 until the next scan, and the positive potential decreases. In this way, each unit pixel is selectively scanned and the #J multiplication signal is outputted to the output terminal 8. [Problems to be solved by the invention] However, it has the following drawbacks and cannot be put into practical use. I'm blocked. Electron-hole pairs generated by the light 17 become signal charges. The signal charge forms a photodiode 1. Diffusion layer 1
1 and the semiconductor substrate 14 near the diffusion layer 11. However, semiconductor substrates 14 other than the semiconductor substrate 14 near the diffusion layer 11

[Deep part of the semiconductor substrate 14, below the oxide film 16, the diffusion layer 12, and the semiconductor substrate 14 below the diffusion layer 12]
), electron-hole pairs are also generated by the light 17. The amount of signal charge is shown in the following equation. λ is the wavelength of light, α is the absorption coefficient of the semiconductor substrate, 2 is the depth of the semiconductor substrate including the diffusion layer 11, and A is a constant. If the electron-hole pairs generated in the semiconductor substrate 14 in the deep part of the semiconductor substrate 14, under the oxide film 16, and under the diffusion layer 12 recombine and disappear, they will not be destroyed, but they will be diffused. layer 12 or the diffusion layer of the adjacent pixel (the drain connected to diode 1 and vertical signal line 6), it mixes with the true signal charge, which means that the solution for solid-state imaging devices is extremely difficult. resulting in a decline. A white or high-luminance line is generated in the vertical direction when light such as a strong spot light is incident (this is called a smear). Smearing not only greatly degrades the image quality of a custom-made solid-state imaging device, but also This poses a practical problem because it generates white or high-luminance lines in the vertical direction, and it also has the problem of hindering the practical use of solid-state imaging devices. In order to solve these conventional problems, the present invention provides a circuit for removing smear components. The purpose of this invention is to improve the resolution of a 1% solid-state imaging device and eliminate smear, thereby improving the imaging slag characteristics. [Means for resolving inter-vertices] The solid-state imaging device of the present invention includes photoelectric conversion elements arranged two-dimensionally in the horizontal and vertical directions, and a first image sensor that sequentially reads out video signals from the photoelectric conversion elements. a second switch element;
．． The first switch element controls the second switch element. In the 'solid-state moat imaging device provided with the second scanning circuit, 1)): The first switch element is connected to the first switch element. It is characterized in that it is controlled by a second scanning circuit. 2) A third switch element connected to a signal line connecting the first switch element and the second switch element is provided. 3) The third switch element is controlled by the second scanning circuit. 4) The third switch element is connected to the output terminal. [Operation] Due to the above configuration of the present invention, smear components are mixed into the vertical signal line connecting the first switch element and the second switch element. By reading out the optical signal with the third switching element immediately before reading out the optical signal on the vertical signal line with the first switching element and reading out the optical signal after completely eliminating the smear component, solid-state imaging completely eliminates the smear peculiar to the device. This can lead to improved resolution and improved imaging characteristics. [Embodiment] FIG. 1 shows an implementation of the solid-state imaging device of the present invention. The difference from the conventional solid-state imaging device shown in FIG. It is composed of transistor n. Also, a third switch element (reset switch) 31 is connected to the vertical signal &A 26 in which smear charges are accumulated, similar to the second switch element (horizontal switch) 23, and the reset switch 31 is controlled by the horizontal scanning circuit. This is a feature of the present invention. In other words, in the conventional solid-state imaging device, smear charges accumulate on the vertical signal line 6, and when reading out the optical signal charges, the optical signal charges and the smear charges are read out at the same time. The smear charge is reset immediately before reading out the signal and charge. The operation of the present invention will be explained. Each vertical switch is selected by the vertical scanning circuit 4 through the vertical gate 24. However, the optical signal charges accumulated in the photodiode 21, which is a photoelectric conversion element, are not transferred to the vertical signal line yet.The primary horizontal scanning circuit 30 passes through the horizontal gate 34 to the horizontal gate 34, and the reset switch 31 is turned on. The smear charge accumulated in the signal line 26 is swept out to the smear output terminal through the horizontal sweep line 32, and then the vertical switch O is passed through the horizontal gate 25 between the horizontal scanning circuits.
By doing so, the optical signal charge of the shifted diode 21 is transferred to the vertical signal line 3. ), it goes without saying that the horizontal switch field is also turned on at the same time by the horizontal gate B.The optical signal charge passes through the vertical signal line 26, the horizontal signal line 27, and is read out to the optical signal output terminal. FIG. 2 shows a structural diagram of a photoelectric conversion element and a vertical switch according to an embodiment of the present invention. The photodiode is composed of an outer diffusion layer 43 and a P-type substrate 41. As shown in FIG. Carriers generated by the incident light 51 are accumulated in the junction capacitance between the n-type diffusion layer 43 and the P-type substrate 41 . However, carriers generated deep in the P-type substrate 4 are accumulated in the n-type diffusion layer 44, which is the drain of the vertical switch. This accumulated charge becomes a smear charge. This smear charge is swept out by the AL wiring line 4 reset switch, which is a vertical signal line. Therefore, the optical signal charge accumulated in the n-type diffusion layer 43 constituting the photodiode is swept out by the vertical gate 46 and the horizontal The gate thief transfers the smear charge to the erased vertical signal line 47 and reads it out to the signal output terminal through the horizontal switch. It goes without saying that the horizontal gate may be 46 and the vertical gate may be a blade. [Effects of the Invention] The present invention eliminates Q by completely sweeping out the smear components accumulated in the vertical signal line from the optical signal line. Suppresses smear, a phenomenon peculiar to solid-state imaging devices. As a result, the effect of increasing the resolution and improving the imaging characteristics of the solid-state imaging device can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a solid-state imaging device according to the present invention, FIG. 2 is a cross-sectional view of a unit pixel of the solid-state imaging device according to the present invention, and FIG. 3 is a block diagram of a conventional solid-state imaging device. Yes, Figure 4 shows the unit II of a conventional solid-state imaging device! FIG. 2 is a cross-sectional view of Li element. 1.21-...Photodiode 2.22...MO8) Transistor 3.23...MO13) ψ for horizontal switch
・・Horizontal scanning gate and wiring 6.26Φ・Vertical signal line 7.27・φ・Horizontal return line 8.28・・Optical signal output end 9.29−・・Vertical scanning circuit 10, 30 @・・Horizontal scanning circuit 31...MO8 for reset switch) Transistor β...Horizontal smear sweep line...Smear output end 11, 12, 43, 49, 44 ・m n-type diffusion layer 13, so, 46'' e K) (POLY-8
i) 14, 41..., P-type semiconductor substrate 15, 47...metal wiring (8 16, 45... oxide film 17, 51... light 18, 48, fist, interlayer film 19, 42) ...?Impurity layer or above Applicant: Seiko Epson Co., Ltd. Representative Patent attorney business trip: Senior affairs and 1 other person 2n Aya 4-rho

Claims (4)

[Claims] (1) A photoelectric conversion element arranged two-dimensionally in the horizontal and vertical directions, first and second switch elements that sequentially read out video signals from the photoelectric conversion element, and the first and second switch elements. A solid-state imaging device comprising first and second scanning circuits for controlling the solid-state imaging device, wherein the first switching element is controlled by the first and second scanning circuits. (2) The solid-state imaging device according to claim 1, further comprising a third switch element connected to a signal line connecting the first switch element and the second switch element. (3) The solid-state imaging device according to claim 2, wherein the third switching element is controlled by the second scanning circuit. (4) The solid-state imaging device according to claim 3, wherein the third switch element is connected to an output terminal.