JPH0735405Y2 - Solid-state imaging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a solid-state image pickup device for transferring and reading out a signal charge from a light receiving section by a charge transfer register, and particularly to a signal input for characteristic measurement. The present invention relates to a solid-state imaging device having a unit.

[Outline of the Invention] The present invention has a charge transfer register for transferring charges from light receiving portions arranged in a line or a matrix, and the charge transfer register is provided with a signal input portion for characteristic measurement. In the device, by providing a high resistance element between the input terminal of the signal input section and the power supply, it is possible to prevent the input terminal from floating when the input terminal of the signal input section is not used. Furthermore, the bonding work of the input terminal of the signal input section is omitted.

[Conventional technology]

Usually, a CCD image sensor has a shift register for transferring charges, and some of the shift registers are provided with a signal input section for measuring characteristics for evaluating transfer efficiency and the like.

FIG. 4 is a block diagram of a conventional CCD image sensor. As shown in FIG. 4, a shift register 102 is arranged along a row of a plurality of photodiodes 101 arranged in a row corresponding to each pixel.

An output buffer 103 is wired on one side of the shift register 102, and the signal transferred by the shift register 102 is output to the outside via the output buffer 103.

Further, a signal input section for measuring characteristics is provided on the opposite side of the shift register 102 to which the output buffer 103 is connected. This signal input section is composed of an input source 104 and an input gate 105. The input gate 105 is provided in a position parallel to the shift register 102, and an input source 104 is provided adjacent to the input gate 105 on the opposite side of the input gate 105 from the shift register 102.

Further, the input source 104 and the input gate 105 are connected to the input terminals 106 and 107, respectively. The input terminal 106 and the input terminal 107 are terminals for measuring the charge transfer characteristics of the shift register before delivery to the user, and when inspecting the characteristics, a required measurement signal is applied to each terminal. .
When it is actually installed in a device or the like and used, it is not used.

[Problems to be solved by the device]

However, in the solid-state imaging device having the signal input section for characteristic measurement as shown in FIG. 4, the input source 104, the input gate 105
When the respective input terminals 106 and 107 of
The input terminals 106 and 107 are in a floating state, and a false signal appears in the output buffer 103. Therefore, in order to prevent the floating state of the input terminal, the user needs to apply a constant voltage from the outside to the input terminal with the device set to the device.

However, in order to apply a constant voltage from the outside,
It is necessary to bond the input terminals 106 and 107 in advance, and bonding the input terminals increases the cost of the product.

In view of the above technical problems, the present invention is directed to a solid-state imaging device having a characteristic measuring signal input section that is used only during characteristic measurement. It is an object of the present invention to provide a solid-state image pickup device that prevents the floating state of the device from being brought into a floating state, and thus omits the bonding work and the like.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the solid-state imaging device of the present invention has a plurality of light receiving portions arranged in a line or a matrix, and a charge transfer register for transferring charges from the light receiving portions. In a solid-state image pickup device in which a register is provided with a signal input section for characteristic measurement, the signal input section is connected to an input terminal and is connected to a required power source through a high resistance element. Here, as the high resistance element, a polysilicon resistance, a diffusion resistance, a MOS resistance or the like can be used. Further, the required power supply is a power supply having a voltage such as a power supply voltage or a ground voltage, and is a power supply obtained internally.

[Action]

In the solid-state imaging device of the present invention, the input terminal of the signal input unit for characteristic measurement is connected to the required power source through the high resistance element.
As a result, when this input terminal is not used, the voltage of the input terminal becomes equal to the voltage of the required power supply, and the floating state of the input terminal is avoided.

〔Example〕

 A preferred embodiment of the present invention will be described with reference to the drawings.

First Embodiment This embodiment is an example of a CCD linear sensor. FIG. 1 shows a circuit diagram of the linear sensor. Multiple photodiodes 1
Are arranged in a row, and a pair of shift registers 3, 3 are provided along the photodiode 1 on both sides of the row of the photodiode 1. Between each photodiode 1 and the pair of shift registers 3, 3, a transfer gate 2, for controlling transfer of optical signal charges accumulated in each photodiode 1 and transferred to the shift registers 3, 3, respectively. 2 are arranged along the row of the photodiodes 1, respectively.

Then, the input section of the output buffer 4 is connected to the terminal section of the shift register 3. The signal charge transferred by the shift register 3 is output as an output signal to the outside through the output buffer 4.

Further, a signal input section for characteristic measurement is provided on the base end side of the shift registers 3, 3 on the side opposite to the output buffer 4 of the shift registers 3, 3. This signal input section is composed of an input source 5 and an input gate 6. The input gate 6 is provided in a position adjacent to the shift register 3 side by side, and the input source 5 is provided adjacent to the input gate 6 on the opposite side of the input gate 6 from the shift register 3.

Further, the input source 5 is connected to the input terminal 7 which is a pad portion and is connected to the power supply line 11 via the high resistance element 9. The input gate 6 is also an input terminal 8 which is a pad section.
It is also connected to the ground line 12 via the high resistance element 10.

FIG. 2 is a sectional view of the linear sensor of this embodiment. An n-type impurity diffusion region 22 that functions as an input source is formed on the surface of the semiconductor substrate, surrounded by a p-type well region 21, and the p-type well region is located adjacent to the n-type impurity diffusion region 22. A gate electrode layer 23 functioning as an input gate is formed on the gate insulating film 24.
The n-type impurity diffusion region 22 and the gate electrode layer 23 function as a signal input portion for characteristic measurement as described later. That is, the n-type impurity diffusion region 22 is connected to the input terminal 7 and the power supply line 11 via the high resistance element 9. Further, the gate electrode layer 23 is connected to the input terminal 8 and also connected to the ground line 12 via the high resistance element 10 in the same manner.

In addition, the p-type well region is adjacent to the gate electrode layer 23.
By patterning on the gate insulating film 24 on 21, the first-layer polysilicon layers 31, 33 and the second-layer polysilicon layers 30,
32 is formed. These polysilicon layers 30 to 33 function as transfer electrodes. The above polysilicon layer 30, 31 signal [Phi _A is supplied to the above polysilicon layers 32 and 33 with the signal [Phi _B is supplied, the transfer electrodes are driven two-phase.

In the CCD linear sensor of this embodiment having such a structure, the input terminals 7 and 8 are terminals for measuring the charge transfer characteristics of the shift register in the manufacturing process. Therefore,
When inspecting the characteristics, each terminal is provided with the required measurement signal. The input terminals 7 and 8 are not used when actually used by being incorporated in a device or the like.

Also, in the case of actually incorporating it into equipment etc.,
Since the high resistance element 9 is provided between the input source 5 and the power supply line 11, the potential of the input source 5 becomes equal to the power supply voltage V _DD . On the other hand, since the high resistance element 10 is provided between the input gate 6 and the ground line 12, the potential of the input gate 6 becomes equal to the ground voltage. Therefore, the input source 5 and the input input gate 6 are each fixed to a required voltage, so that the floating state is avoided.

Further, since the potentials of the input source 5 and the input gate 6 are fixed, it becomes unnecessary for the user to apply a constant voltage from the outside to this input terminal. For this reason,
It is not necessary to bond the input terminals of the signal input section, and the production cost is reduced.

Second Embodiment This embodiment is an example of a CCD area sensor, and FIG. 3 is a circuit diagram of the area sensor. A plurality of photodiodes 41 arranged in a matrix corresponding to each pixel 41
Vertical shift registers 43 are arranged along the columns. A transfer gate 42 for controlling transfer of charges accumulated in the photodiode 41 and transferred to the vertical shift register 43 is arranged between each photodiode 41 and the vertical shift register 43. Then, a horizontal shift register 53 electrically connected to the vertical shift register 43 is provided. The output buffer 44 is connected to the end of the horizontal shift register 53, and the signal transferred by the horizontal shift register 53 is output to the outside via the output buffer 44.

Further, a signal input section for characteristic measurement is provided at the end of the horizontal shift register 53 opposite to the side to which the output buffer 44 is connected. This signal input section has an input source 45 and an input gate 46.
Composed of. The input gate 46 is provided in a position parallel to the horizontal shift register 53, and an input source 45 is provided adjacent to the input gate 46 on the side of the input gate 46 opposite to the horizontal shift register 53.

Further, the input source 45 is connected to the input terminal 47, which is a pad portion, and is connected to the power supply line 51 via the high resistance element 49. The input gate 46 is connected to the input terminal 48, which is a pad portion, and is also connected to the ground line 52 via the high resistance element 50.

In the CCD area sensor of the present embodiment having such a structure, the input terminals 47 and 48 are terminals for measuring the charge transfer characteristics of the shift register in the manufacturing process, and when inspecting the characteristics, each terminal is The signal for the required measurement is provided.

Further, when actually incorporated in a device or the like, the input terminals 47 and 48 are not used, the input source 45 is made equal to the voltage of the power supply line 51 through the high resistance element 49, and the input gate 46 has a high resistance. It is made equal to the voltage of the ground line 52 through the element 50. Therefore, since a constant voltage is applied to each of the input source 45 and the input gate 46, the floating state is avoided, and the adverse effect that a false signal appears at the output section can be prevented.

Further, the bonding work of the input terminals 47 and 48 is unnecessary, and the production cost is reduced.

The solid-state imaging device according to the present invention may be modified without departing from the gist of the present invention.

[Effect of device]

The fixed image pickup device of the present invention has a signal input unit for measuring characteristics, and the required power source is connected to the input terminal of the signal input unit via a high resistance element, so that the signal input unit is not used. At times, the signal input section is set in a floating state to prevent a false signal from appearing at the output section. Moreover, since the bonding work of the input terminal of the signal input unit can be omitted, the production cost can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing the structure of the first embodiment of the solid-state image pickup device of the present invention, FIG. 2 is a sectional view of the solid-state image pickup device of the first embodiment, and FIG. It is a block diagram which shows the structure of 2nd Example of the solid-state imaging device of a device. FIG. 4 is a block diagram showing the structure of an example of a conventional solid-state imaging device. 1,41 …… photodiode 2,42 …… transfer gate 3,43,53 …… shift register 4,44 …… output buffer 5,45 …… input source 6,46 …… input gate 7,8,47, 48 …… Input terminal of signal input part 9,10,49,50 …… High resistance element 11,51 …… Power supply line 12,52 …… Grounding wire 21 …… P-type well region 22 …… N-type impurity Diffusion region 23 …… Gate electrode layer 24 …… Gate insulating film 30,32 …… Second layer polysilicon layer 31,33 …… First layer polysilicon layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H01L 29/762 H04N 5/335 F

Claims (1)

[Scope of utility model registration request] 1. A plurality of light receiving portions arranged in a line or in a matrix and a charge transfer register for transferring charges from the light receiving portions, and the charge transfer register is provided with a signal input portion for characteristic measurement. In the solid-state imaging device, the signal input section is connected to an input terminal and is connected to a required power source through a high resistance element.