JPH0693764B2 - Photoelectric conversion device - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a semiconductor of the first conductivity type.
And a second control electrode region different from the first conductivity type.
The output circuit including a capacitive load is made of a conductive semiconductor and is electrically
Electrically connected first main electrode region and second conductivity type semiconductor
A second main electrode region consisting of the body, and
A carrier capable of accumulating the generated carriers in the control electrode region.
Communication based on multiple carriers and accumulated carriers
In the refresh operation after reading the
The main electrode area of the
Refresh means to remove accumulated carriers,
Equipped with storage operation, read operation and refresh operation
The present invention relates to a photoelectric conversion device that performs

[0002]

2. Description of the Related Art FIG. 6 (A) is a diagram of JP-A-60-12759.
FIG. 6B is a plan view of the photoelectric conversion device described in Japanese Patent Laid-Open No. 60-12765, FIG. 6B is a sectional view taken along the line I-I, and FIG. 7 is an equivalent circuit diagram thereof.

In each drawing, photoelectric conversion cells are formed and arranged on an n-silicon substrate 101, and the photoelectric conversion cells are adjacent to each other by an element isolation region 102 made of SiO ₂ , Si ₃ N ₄ or polysilicon. It is electrically insulated from the photoelectric conversion cell.

Each photoelectric conversion cell has the following structure.

[0005] low impurity concentration formed by epitaxial technique or the like n ^- p region 104 by doping p-type impurities is formed on region 103 is formed, p region 1
In 04, an n ⁺ region 105 is formed by an impurity diffusion technique or an ion implantation technique. P region 104 and n ⁺ region 105 are the base and emitter of the bipolar transistor, respectively.

N ⁻ region 1 in which each region is formed in this way
An oxide film 106 is formed on the oxide film 03, and a capacitor electrode 107 having a predetermined area is formed on the oxide film 106. The capacitor electrode 107 is p
A capacitor C _ox is formed so as to _{face the} region 104. By applying a pulse voltage to this capacitor electrode 107,
The potential of the floating p region 104 is controlled.

Besides, the emitter electrode 108 connected to the n ⁺ region 105, the wiring 109 for reading a signal from the emitter electrode 108 to the outside, the wiring 110 connected to the capacitor electrode 107, and the back surface of the substrate 101 having a high impurity concentration. n
An electrode 112 for applying a potential to the ⁺ region 111 and the collector of the bipolar transistor is formed.

Next, the basic operation will be described. First, it is assumed that the p region 104 which is the base of the bipolar transistor is in the initial state of negative potential. Light 1 in this p region 104
13 is incident, carriers corresponding to the amount of light are generated in the p region 10
4 is accumulated (accumulation operation). The base potential changes due to the accumulated charge, and the potential change causes the emitter
The collector current is controlled, and an electric signal corresponding to the amount of incident light is read from the floating emitter electrode 108 (reading operation). Further, in order to remove the carriers accumulated in the p region 104, the emitter electrode 108 is grounded and the refresh positive voltage pulse is applied to the capacitor electrode 107. By applying this positive voltage, the p region 104 is biased in the forward direction with respect to the n ⁺ region 105, and the accumulated carriers are removed. Then, when the refresh pulse falls, the p region 104 returns to the initial state of negative potential (refresh operation). Thereafter, the above-mentioned operations of accumulation, reading and refresh are repeated.

In summary, the scheme proposed here is
Carriers generated by light incidence are accumulated in the p region 104 which is the base, and the amount of accumulated charge controls the current flowing between the emitter electrode 108 and the collector electrode 112. Therefore, the accumulated carriers are read after being subjected to charge amplification by the amplification function of each cell, and high output, high sensitivity, and low noise can be achieved.

The potential Vp generated in the base by the carriers accumulated in the base by photoexcitation is given by Q / C. Here, Q is the charge amount of carriers accumulated in the base, and C is the capacitance connected to the base. As is clear from this equation, in the case of high integration, both Q and C become smaller as the cell size shrinks, and the potential Vp generated by photoexcitation is kept almost constant. Therefore, it can be said that the method proposed here is advantageous for future high resolution.

[0011]

The change in the base potential Vb while the positive refresh voltage is being applied to the capacitor electrode 107 in the refresh operation can be obtained from the following equation.

[0012] However, Cbe represents a base-emitter capacitance, Cbc represents a base-collector capacitance, and Ib represents a base current.

FIG. 8 is a graph showing the change over time in the base potential Vb while the positive refresh voltage is being applied.

In the graph, the initial base potential at the time when the refresh pulse is applied differs depending on the magnitude of the accumulated voltage Vp. That is, when the refresh positive voltage pulse is applied to the capacitor electrode 107 in a state in which the base potential, which was a negative potential in the initial state, changes in the positive direction by the accumulation voltage Vp due to the accumulation operation, the initial base potential is the accumulated voltage. This is because it becomes higher by Vp.

Further, as shown in the graph, the time period during which the initial base potential is maintained varies depending on the magnitude of the initial base potential, but after that time, the base potential Vb uniformly decreases regardless of the initial base potential. . Therefore, if the refresh time t is sufficiently long, the base potential Vb can be almost 0 V regardless of the magnitude of the accumulated voltage Vb, and the base potential Vb can be set at the time when the refresh pulse falls.
Can be returned to a predetermined negative potential in the initial state.

However, in order to achieve a high speed operation, the refresh time t = to is set and the base potential V is actually set.
The refresh operation is completed when b = Vk. Thus, even if there is a residual potential in the base potential Vb, if the base potential Vb is always the constant potential Vk at the refresh time t = to, the base potential Vb is kept constant negative at the time when the refresh pulse falls. The potential can be returned to the potential, and the negative potential can be set to the initial state.

However, in the conventional photoelectric conversion device,
When the refresh operation is repeated, the residual potential Vk gradually decreases, which causes a problem that an afterimage time occurs.

In FIG. 8, it is assumed that the high illuminance cell has an initial base potential of 0.8V and the low illuminance cell has an initial base potential of 0.4V. And refresh time to
After elapse of time, the base potential Vb of the high illuminance cell becomes the predetermined residual potential Vk, but the base potential Vb of the low illuminance cell becomes the residual potential V ₁ , which is lower than Vk. When the refresh pulse falls in this state, the base potential Vb of the low-illuminance cell falls below the initial negative potential, and the accumulation and read operations are performed from this low potential. Therefore, when the refresh operation is repeated in the low illuminance state, the residual potential of the base potential gradually decreases, and even in the high illuminance state in this state, an output lower than the output corresponding to the amount of incident light can be obtained. That is, the afterimage phenomenon appears.

As a cause of this, it is conceivable that the holes in the base region are recombined and become insufficient by repeating the refresh operation. Therefore, the afterimage phenomenon becomes conspicuous when the low illuminance state where the shortage of holes cannot be compensated continues.

Further, in the conventional photoelectric conversion device, when they are arranged in a matrix, there is a problem that a blooming phenomenon occurs as described below.

FIG. 9 is a schematic circuit diagram of an area sensor using a conventional photoelectric conversion device. In the figure, the conventional photoelectric conversion cells 120 are arranged in a 3 × 3 matrix, and the emitter electrodes 108 thereof are commonly connected to vertical lines for each column. In addition, the capacitor electrodes 107 are commonly connected for each row, and the reading or refreshing operation is performed for each row by the positive voltage from the vertical scanning unit.

However, when a photoelectric conversion cell receives strong light irradiation during the storage operation and the potential of its base region 104 becomes higher than the potential of the emitter region 105, the emitter electrode of the photoelectric conversion cell does not perform the read operation. 108
The potential of the vertical line connected to will rise.
Therefore, when another photoelectric conversion cell having the emitter electrode 105 connected to the same vertical line is performing a read operation, a read signal is output to the vertical line even if the other photoelectric conversion cell is not irradiated with light. It will be in the output state.
That is, in this case, the blooming phenomenon appears in the vertical direction.

[0023]

In order to solve the above-mentioned conventional problems, the photoelectric conversion device according to the present invention is of the first conductivity type.
Of the control electrode region made of the semiconductor and the first conductivity type
Output made of different second conductivity type semiconductors including capacitive load
A first main electrode area electrically connected to the circuit and a second conductor area.
And a second main electrode region made of an electro-type semiconductor,
Stores carriers generated by light emission in the control electrode region
Multiple stackable transistors and accumulated carriers
The refresh operation after reading the signal based on
Hold the first main electrode region at a reference potential,
Refresh to remove carriers accumulated in the electrode area
And a read operation and a read operation.
In the photoelectric conversion device performing the reshing operation,
In each control electrode area of the transistor, the first main
Separately from the polar region, the second conductivity type and the first main
A semiconductor region having a lower impurity concentration than the electrode region is provided
Together with the plurality of transistors connected to the semiconductor region.
Peak signal to detect the peak signal in the transistor
A detection circuit is provided.

[0024]

Thus, in order to form a diode structure between the control electrode region and the semiconductor region, carriers can be injected into the control electrode region by applying an appropriate voltage to the semiconductor region. . Therefore, for example, the potential of the control electrode region can be made sufficiently high at the start of the refresh operation, and the potential of the control electrode region at the end of the refresh operation can be set to a desired constant value. That is, the occurrence of the afterimage phenomenon as in the conventional case is prevented.

Further, even when exposed to strong light irradiation, excess carriers are removed through the diode structure, so that the blooming phenomenon can be prevented.

A plurality of transistors are connected to the semiconductor region.
Peak signal to detect the peak signal in the transistor
Peak value detection from the semiconductor area by providing a detection circuit
Since it is easy to perform
The image device can be easily configured.

[0027]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1A is a plan view of a photoelectric conversion cell of an embodiment of the photoelectric conversion device according to the present invention, FIG. 1B is a sectional view taken along the line AA, and FIG. 2 is its equivalent circuit. It is a figure.

In each figure, n ⁻ on the n silicon substrate 1
An epitaxial layer 2 is formed in which photoelectric conversion cells electrically isolated from each other by an element isolation region 3 are arranged. However, the element isolation region 3 is formed of SiO ₂ ,
It is made of Si ₃ N ₄ , polysilicon, or n ⁺ diffusion region.

On the n ^- epitaxial layer 4, a p base region 4 which is a control electrode region of a bipolar transistor is formed by an impurity diffusion or ion implantation method, and an n ⁺ emitter region which is a first main electrode region is further formed therein. 5 and p
An n region 6 having a concentration similar to that of the base region 4 is formed by impurity diffusion or ion implantation. Here, the diode structure is formed by the n region 6 and the p base region 4.

An oxide film 7 is formed on the n ^- epitaxial layer 2 thus formed, and a capacitor electrode 8 for applying a pulse to the p base region 4 is formed of polysilicon or the like on the oxide film 7. Has been done.

In addition, an emitter electrode 9 connected to the n ⁺ emitter region 5, an electrode 10 connected to the n region 6, an n ⁺ region 11 and a collector electrode 12 on the back surface of the substrate 1, and on each photoelectric conversion cell. Each protective film 13 is formed. The collector, which is the second main electrode region, is an n ^- epita
It is composed of the axial layer 2 and a part of the n-silicon substrate 1.
It

Next, the photoelectric conversion of the present embodiment having the above structure
The operation of the replacement cell will be described.

First, in the accumulation operation, the p base region 4
Is in the initial state of negative potential, the emitter region 5 is set to a floating state of zero potential, the capacitor electrode 8 is set to zero potential, and the n region 6 forming the diode is set to zero or slightly negative potential. The collector electrode 12 is maintained at a positive potential thereafter. Light enters in this state, and carriers (here, holes) corresponding to the amount of light are accumulated in the p base region 4.

Here, when the intense light is irradiated and the potential of the p base region 4 is greatly increased, the diode composed of the p base region 4 and the n region 6 is forward biased, and the p base region 4 is biased. The holes excessively accumulated in 4 are removed to the outside through the electrode 10. Therefore, n ⁺
The potential of the emitter region 5 does not change, and the blooming phenomenon does not occur.

Next, in the read operation, the n ⁺ emitter region 5 and the n region 6 are brought into a floating state, and a read positive voltage pulse is applied to the capacitor electrode 8. As a result, as described above, the electric signal corresponding to the amount of incident light is read out to the emitter electrode 9.

Next, in the hole injection operation, the capacitor electrode 8 is set to zero potential and the n ⁺ emitter region 5 is set to a floating state. Then, an appropriate positive potential is applied to the n region 6 forming the diode to bring the diode into a reverse bias state, and the depletion layer thereof reaches the electrode 10. As a result, a punch-through operation occurs, holes are injected into the p base region 4 through the n region 6, and the potential of the p base region 4 rises.

Next, in the refresh operation, the n ⁺ emitter region 5 and the n region 6 are grounded. When a positive voltage refresh pulse is applied to the capacitor electrode 8 in this state, the holes accumulated in the p base region 4 are removed through the n ⁺ emitter region 5 and the n region 6. However, since the potential of the p base region 4 is sufficiently high due to the hole injection operation, the initial base potential immediately after the refresh pulse application is sufficiently higher than the residual potential Vk even in the dark state (Fig. 8). Therefore,
When the refresh time to has elapsed, the potential of the p base region 4 becomes the constant potential Vk regardless of the level of illuminance.
Since the positive voltage pulse for refresh falls in this state, the p base region 4 is always in the initial state of a constant negative potential.

As described above, by inserting the hole injection operation, the holes in the p base region 9 will not run short even if the refresh operation is repeated, and the afterimage phenomenon in the low illuminance state can be completely prevented. You can

Next, an example of an image pickup device configured by two-dimensionally arranging photoelectric conversion cells having such a structure and basic operation will be described with reference to the drawings.

FIG. 3 is a circuit diagram of an image pickup device in which the photoelectric conversion cells of FIG. 1 are two-dimensionally arranged, and FIG. 4 is a timing chart for explaining the operation thereof.

In FIG. 3, the photoelectric conversion cell 20 is 3 × 3.
, And the capacitor electrodes 8 of the photoelectric conversion cells 20 are commonly connected to the horizontal lines 21, 21 ', 21 "row by row. Each horizontal line connects the transistors 23, 23', 23". Connected to the terminal 24 via.
A positive voltage pulse for reading φr is applied to the terminal 24.
Also, each horizontal line has transistors 25, 25 ', 2
5 ″ is connected to the terminal 26, and the refresh positive voltage pulse φf is applied to the terminal 26.

Pulse signals φr _{1 to} φr ₃ are applied from the vertical shift register 22 to the gate electrodes of the transistors 23, 23 ′ and 23 ″, and the transistors 25 and ₂ are applied.
Pulse signals φf _{1 to} φf ₃ are similarly applied from the vertical shift register 22 to the respective gate electrodes 5 ′ and 25 ″.

The electrodes 10 of the photoelectric conversion cells 20 are commonly connected to the horizontal lines 27, 27 ', 27 "row by row, and a pulse signal φ ₁ from the vertical shift register 28 is connected to each horizontal line.
~ Φ ₃ is applied respectively.

Further, the emitter electrode 9 of the photoelectric conversion cell 20
Are commonly connected to the vertical lines 29, 29 ', 29 "for each column. Each vertical line is grounded through the refreshing transistors 30, 30', 30" and is connected to the photoelectric conversion cell. It is connected to an output line 34 through transistors 33, 33 ', 33 "for outputting a read signal serially.

The gate electrodes of the transistors 30, 30 'and 30 "are commonly connected to the terminal 31, and the pulse signal φrs is applied to the terminal 31. Also, the transistors 33 and 30'.
Pulse signals φh _{1 to} φh ₃ are applied from the horizontal shift register 32 to the respective gate electrodes 33 ′ and 33 ″.

The output line 34 is grounded via the refreshing transistor 36, is connected to the gate electrode of the signal amplifying transistor 35, and the amplified signal is output from the terminal 38.

Next, the operation of such an image pickup apparatus will be described with reference to FIG.

First, it is assumed that the accumulation operation is performed until time t ₁ and holes corresponding to the amount of incident light are accumulated in the p base regions 4 in each photoelectric conversion cell 20. However, as already described, even if strong light is incident on some of the photoelectric conversion cells 20, the excess holes pass through the electrode 10 and the horizontal line 2.
The vertical lines 29, 29 ', 29 "remain floating at zero potential because they are removed to 7, 27' or 27".

At time t ₁ , the pulse signal φr ₁ rises to turn on the transistor 23, and then the pulse φr rises to apply the positive voltage for reading to the horizontal line 21 and the photoelectric conversion cell of the first row. 20 starts the read operation. By this read operation, the read signals of the photoelectric conversion cells in the first row are changed to the vertical lines 29, 29 ', 2
9 ″. When the read operation is completed, the pulse signal φlrs turns on the transistor 36,
The residual potential of the output line 34 is refreshed.

At time t ₂ , the pulse signal φh ₁ rises and the transistor 33 is turned on. As a result, the signals of the photoelectric conversion cells in one row and one column which have been read out on the vertical line 29 are transferred to the transistor 33 and the output line 34.
Is input to the transistor 35 via the
It is output from 8. When this output operation ends, the pulse signal φlrs rises and the output line 34 is refreshed. Then, the pulse signals φh ₂ and φh ₃ sequentially rise, and the signals of the photoelectric conversion cells in the 1st row, 2nd column and the 1st row, 3rd column are sequentially output from the terminal 38 in the same manner, and the output line 34 is refreshed each time.

When the output operation is completed, the pulse signal φ ₁ of the vertical shift register 28 rises at time t ₃ ,
A positive voltage is applied to the electrode 10 of the photoelectric conversion cell 20 in the first row, and the hole injection operation as described above is performed.

Next, at time t ₄ , the pulse signal φf
₁ and φrs rise, the transistor 25 is turned on, and the transistors 30, 30 ', 30 "
Turns on and each vertical line is grounded. continue,
The pulse signal φf rises, the positive voltage pulse for refresh is applied to the horizontal line 21, and the refresh operation is performed as described above.

Thus, with respect to the photoelectric conversion cells 20 in the first row, the read, hole injection and refresh operations are completed, and the accumulation operation is started at time t ₅ .

The same operation as in the first row is performed for each photoelectric conversion cell 20 from the time t ₅ to the second row and from the time t ₆ to the third row. That is, the pulse signal φ
The photoelectric conversion cells 20 in the second row are selected by the successive rise of r ₂ , φ ₂ and φf ₂ , and the read, hole injection and refresh operations are performed. Then at time t _6, at the same time when the second row enters the accumulation operation, the pulse signal [phi] r _3, phi ₃ and .phi.f ₃ are successively rising third row of photoelectric conversion cells 20 is selected, the respective operation is similarly Done. When the third row enters the accumulation operation, the first row is selected and the same is repeated thereafter.

In this way, all photoelectric conversion cells 20
A read signal corresponding to the incident light intensity of is output serially from the terminal 38. Note that the photoelectric conversion cells 20 in each row have a constant storage operation time, and thus can be applied to, for example, a television video camera.

FIG. 5 (A) uses the photoelectric conversion cell of FIG.
An embodiment of the image pickup device (photoelectric conversion device) of the present invention will be shown.
The circuit diagram and FIG . 5B are timing charts showing the operation of the image pickup apparatus.

In FIG. 5A, three photoelectric conversion cells 20 are arranged one-dimensionally, collector electrodes 12 are commonly connected, and a positive voltage is applied. Further, each capacitor electrode 8 is commonly connected to a terminal 41 via a line 40,
A pulse signal φr for reading or refreshing is applied to the terminal 41. Furthermore, the emitter electrode 9
Are connected to vertical lines 44, 44 ', 44 ", respectively,
The electrodes 10 of the diodes are commonly connected to the horizontal line 42. The horizontal line 42 is connected to the control circuit 43,
The pulse signal φi is applied or grounded.

The vertical lines 44, 44 ', 44 "are grounded via transistors 45, 45', 45", respectively. Further, the gate electrodes of the transistors 45, 45 ', 45 "are commonly connected to a terminal 47 via a line 46, and a signal φrs is applied to the terminal 47.

Further, the vertical lines 44, 44 ', 44 "
Are connected to one of the main electrodes of the transistors 48, 48 ', 48 ", respectively.
8 ', 48 "gate electrode is connected to terminal 5 via line 49
0 is commonly connected, and the signal φt is applied to the terminal 50. The other main electrodes of the transistors 48, 48 ', 48 "are respectively provided with capacitors 51, 51', 5 for storing charges.
Grounded via 1 ″ and transistor 5
It is connected to the output line 54 via 3, 53 ', 53 ".

The gate electrodes of the transistors 53, 53 ', 53 "are connected to the parallel output terminals of the shift register 52, and the signals φh _{1 to} φh ₃ are output from the respective parallel output terminals.

The output line 54 is grounded via a transistor 55 for refreshing the output line 54, and is also connected to the gate electrode of a transistor 57 which is an output amplifier. The gate electrode of the transistor 55 is connected to the terminal 56, and the signal φlr is connected to the terminal 56.
s is applied. In addition, the output terminal 5 of the transistor 57
8 is an output terminal 60 via a capacitor and an amplifier 59.
It is connected to the.

The output terminal of the control circuit 43 is connected to the amplification degree selection terminal of the amplifier 59 and adjusts the amplification degree of the amplifier 59 based on the input signal from the horizontal line 42.

Next, the operation of the image pickup apparatus having such a structure will be described with reference to FIG.

First, by setting the pulse signals φrs and φlrs to the high level, the transistors 45, 45 ',
45 ″ and the transistor 55 are turned on. As a result, each emitter electrode 8 of the photoelectric conversion cell 20 and the output line 54 are grounded, and the residual charge on the output line 54 is removed.

Then, at time t ₁ , the pulse signal φ
t rises and the transistors 48, 48 ', 48 "are turned off.
The N state is set. As a result, the charge storage capacitor 5
1, 51 ′ and 51 ″ are grounded and residual charges are removed.

Then, at time t ₂ , the pulse of the signal φt falls and the pulse signal φi from the control circuit 43 rises. As a result, a positive voltage is applied to the horizontal line 42 until time t _3, and holes are injected into the p base region 4 of each photoelectric conversion cell 20 (hole injection operation).

At time t ₃ , the pulse signal φi falls and the horizontal line 42 is set to the ground potential. Also,
The pulse signal φr rises, and a positive refresh voltage is applied to the capacitor electrode 8 of each photoelectric conversion cell 20.
Since each emitter electrode 8 is grounded, the refresh operation is performed as described above, and the signal φr is generated at the time point t _4.
Then, the p base region 4 of each photoelectric conversion cell returns to the initial state of negative potential. When the refresh operation is completed, signals φrs and φlrs fall, and transistors 45, 45 ′, 45 ″ and 55 are turned off.

In this state, holes of the electron-hole pairs excited by the incident light are accumulated as optical information in the p base region 4 of each photoelectric conversion cell 20, and the base potential of each cell is the initial value. Each rises from the negative potential by the accumulated voltage corresponding to the amount of incident light (accumulation operation).

When the accumulation operation is performed for a desired time, the control circuit 43 first brings the horizontal line 42 into a floating state. In addition, the signal φt is set to the high level and the transistors 48, 4
8'and 48 "are turned on, and vertical lines 44 and 4
4 ', 44 "and charge storage capacitors 51,51', 5
1 ″ and 1 ″ are connected.

Then, at time t ₅ , the signal φr rises and the read positive voltage is applied to the capacitor electrode 8 of each photoelectric conversion cell. As a result, the read operation is performed as described above, and the read signal corresponding to the optical information of each photoelectric conversion cell 20 is transferred to the charge storage capacitors 51 and 5.
1 ′, 51 ″ respectively. At the same time, a read signal corresponding to the optical information of each photoelectric conversion cell 20 is also output to the electrode 10 through each diode. Since they are commonly connected to the line 42, the read signal of the photoelectric conversion cell having the highest incident light amount appears on the horizontal line 42 as a peak voltage.
The control circuit 43 uses the peak voltage to amplify the amplifier 59.
Of the read signal is controlled to suppress the spread of the read signal, and it also functions as an automatic diaphragm.

When the amplification degree of amplifier 59 is adjusted in this way, signals φr and φt fall and signal φlr.
A pulse of s is applied to terminal 56. This turns off transistors 48, 48 ', 48 "and refreshes output line 54.

Subsequently, from time t ₆ , the shift register 52
To operate the charge storage capacitors 51, 51 ', 5
The read signals accumulated from 1 ″ are sequentially output. First, when the pulse signal φh ₁ output from the first output terminal of the shift register 52 rises, the transistor 53
Is turned on, and the read signal stored in the charge storage capacitor 51 is read out to the output line 54. The read signal is input to the amplifier 59 whose amplification degree is adjusted via the transistor 57, and is output from the terminal 60 to the outside. Then, when the signal φh ₁ falls, the signal φlr
s rises, the output line 54 is grounded through the transistor 55, and the residual charge is removed.

Similarly, the signals φh ₂ and φh ₃ output from the shift register 52 sequentially rise, and the read signals stored in the charge storage capacitors 51, 51 ′ and 51 ″ are sequentially read out to the output line 54. At the same time, every time each signal is read, the pulse signal φlrs rises and the output line 54 is refreshed, whereby the read signals of all the photoelectric conversion cells 20 are serially output from the amplifiers 59 whose amplification degree is adjusted. Similarly, the refreshing operation, the accumulating operation, and the reading operation are repeated, and the peak value is detected and the amplification degree of the amplifier 59 is adjusted each time the reading operation is performed.

[0075]

As described in detail above, in the photoelectric conversion device according to the present invention, a semiconductor region having the same conductivity type as that of the first main electrode region of the transistor and having a low impurity concentration is provided in the control electrode region. And form a diode structure. Therefore, by applying an appropriate voltage to this semiconductor region, carriers can be injected into the control electrode region at appropriate times. Therefore, for example, the potential of the control electrode region can be made sufficiently high at the start of the refresh operation, and the potential of the control electrode region at the end of the refresh operation can be set to a desired constant value. That is, the occurrence of the afterimage phenomenon as in the conventional case is prevented.

Further, even in the case of receiving strong light irradiation, excessive carriers are removed through the diode structure, so that the blooming phenomenon can be prevented.

Furthermore, since the peak value can be easily detected from the semiconductor region, an image pickup device having a photometric function can be easily constructed.

[Brief description of drawings]

1 (A) is a photoelectric conversion of the photoelectric conversion device according to the present invention
A schematic plan view of the cell , (B) is a sectional view taken along the line AA.

FIG. 2 is an equivalent circuit diagram of the photoelectric conversion cell of FIG.

FIG. 3 is a circuit diagram of an imaging device using the photoelectric conversion cell of FIG.
Is.

FIG. 4 is a timing chart for explaining the operation of the image pickup apparatus in FIG.

FIG. 5A is a schematic diagram of the present invention using the photoelectric conversion cell of FIG.
FIG. 3B is a circuit diagram showing an embodiment of the image pickup apparatus, and FIG. 3B is a timing chart for explaining the operation thereof.

FIG. 6A is a schematic plan view of a conventional photoelectric conversion device,
(B) is the II sectional view taken on the line.

7 is an equivalent circuit diagram of the photoelectric conversion device of FIG.

FIG. 8 is a graph showing a change with time of a base potential during a refresh operation.

FIG. 9 is a circuit diagram showing an example of an image pickup device using a conventional photoelectric conversion device.

[Explanation of symbols]

1 substrate 2 n ^- epitaxial layer 4 p base region 5 n ⁺ emitter region 6 n region 8 capacitor electrode 9 emitter electrode 10 electrode 12 collector electrode

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-60-12761 (JP, A) JP-A-60-12762 (JP, A) JP-A-61-144062 (JP, A) JP-A-61- 285757 (JP, A) JP 62-128678 (JP, A) JP 62-185368 (JP, A)

Claims (1)

[Claims] 1. A control electrode region made of a semiconductor of the first conductivity type.
And a semiconductor of a second conductivity type different from the first conductivity type
Connected to an output circuit that includes a capacitive load
One main electrode region and a second conductive type second semiconductor
A main electrode region and a carrier generated by incident light.
A plurality of transistors capable of accumulating in the control electrode region
And after reading the signal based on the accumulated carrier
In the refresh operation, the first main electrode area is used as a base.
The carrier accumulated in the control electrode region is maintained at a quasi-potential.
A refreshing means for removing the
Photoelectric conversion for writing, reading, and refreshing operations
In the device, the control voltage of each of the plurality of transistors is
In addition to the first main electrode region, the second conductive layer is formed in the pole region.
And of a lower impurity concentration than the first main electrode region.
And a semiconductor region is provided in the semiconductor region.
Connected, peak signal in the plurality of transistors
Specially equipped with a peak signal detection circuit for detecting
Photoelectric conversion device.