JPH02243073A - Solid-state image pickup device - Google Patents

Abstract

PURPOSE:To control overflow of a charge and to ensure charge quantity control by supplying an electric signal controlling a prescribed quantity for a prescribed horizontal blanking period and controlling the charge quantity stored in a sensor. CONSTITUTION:A signal charge in response to the light receiving quantity of a sensor section 1 is transferred to a transfer section 11 corresponding to a vertical shift register 2 for a vertical blanking period. Biphase clocks thetav1, thetav2 are given to terminal tr1, tr2 of the register 2 as shown in waveform diagram and the signal charge is transferred to unidirectional transfer sections adjacent to each other sequentially for a horizontal blanking period. Then a signal for each horizontal line is transferred to the horizontal shift register 3 and the signal for each horizontal line for a horizontal video period is read from a terminal (t). Thus, the signal charge generated and stored in response to the photo receiving quantity in sensor sections S1, S2, S3... is transferred to a storage section of transfer sections T1, T2, T3..., that is, read out.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solid-state imaging device having a C0D (charge capsid device) configuration, and particularly to a solid-state imaging device using an interline transfer method.

CCDC using normal interline transfer method
A solid-state imaging device has a common semiconductor substrate, for example, a silicon substrate, as shown in FIG. A vertical shift register (2) having a CCD configuration is disposed on the negative side of the sensor part (1), which is arranged in a plurality of sensors in the vertical direction (hereinafter referred to as the vertical direction), and arranged on the same line in each vertical direction. A horizontal shift register (3) having a CCD configuration is similarly provided at the end of each shift register (2).

For example, in a television video, during the vertical blanking period, signal charges generated according to the amount of light received by the sensor part (1) are transferred to the corresponding vertical shift register (2).
), and in each horizontal blanking period, the signal charges of each horizontal line of each vertical shift register (2) are sequentially transferred to a horizontal shift register (3), and are read out sequentially from the output terminal t in each horizontal video period. done to. In this case, charge is transferred from each sensor unit (1) to the vertical shift register (2), for example, every other horizontal line, and one
The signal of one part (1) of each sensor on every other horizontal line is read out, and the signal of one part (1) of each sensor on another horizontal line is read out in an even-numbered field section. A so-called interlaced scanning method is adopted.

Even in such a solid-state imaging device, it is desirable to control the amount of accumulated charge and perform, for example, gamma correction. As a method for this gamma correction, for example, it is possible to use an external electrical signal to move the charge to the overflow drain region to prevent blooming.If this control is performed at an arbitrary timing during the monthly vertical period, the control electrical signal may leak into the imaging signal and deteriorate the quality of the imaging signal.

The present invention aims to provide a solid-state imaging device using an interline transfer method that can reliably control the amount of charge by controlling the overflow of charges to the overflow drain region without causing such drawbacks. It is something to do.

The present invention will be described in detail below, but also in the present invention,
As explained in FIG. 1, a large number of sensor parts (1), that is, light receiving parts are arranged and formed on a common semiconductor substrate, and a vertical shift register (2) and a horizontal shift register (3) are arranged.
).

The present invention will be described in detail with reference to FIGS. 1 to 4. FIG. The figure is III-III.
FIG. 4 is a sectional view taken along the line IV-IV. In the figure, (4) is a semiconductor substrate, for example, a silicon substrate having a P-type conductivity type, and an insulating layer (5), for example, a 5iOz layer, is formed on the surface of this substrate. In the illustrated example, the shift register (2) has a buried channel type configuration, and therefore, the N-type region (6) of a conductivity type different from the base body (4) is in the shift register (2). It is formed in a strip shape along the direction perpendicular to the portion constituting the base body (4), facing the -main surface (4a) of the base body (4). (7) is a channel stopper region having the same conductivity type as the substrate (4) and having a high impurity concentration;
As shown with diagonal lines in the figure, between each sensor part (1),
They are provided facing the main surface (4a) so as to separate the sensor portion (1) and the shift register (2) from each other. Then, an overflow drain region (9) consisting of an N-type high impurity concentration region of a conductivity type different from that of the base body (4) is provided adjacent to each sensor part (1) via an overflow control section (8). It is provided facing the main surface (4a).

Further, a gate portion (10) is provided between each sensor portion (1) and the corresponding shift register (2).

The shift register (2) includes a transfer section (11) provided corresponding to each sensor part (1) on the corresponding vertical line.
) are arranged in an array. In the illustrated example, the shift register (2
) is configured as a two-phase clock type, and in this case, each transfer section (11) is formed of a relatively thin insulating layer (5A), for example.
and a thick insulating layer (5B), on which electrodes (12A) and (12B) are formed, respectively, forming a so-called transfer gate part (13^) and a storage part. A gate portion (13B) is configured. Electrodes (12A) in each transfer section (11)
) and (12B) are electrically connected to each other. Fourth
In the example shown in the figure, the insulating layer (5A) under the electrodes (12A) (12B) is used to make the potential depth different between the transfer gate part and the storage gate part of the vertical shift register.
Although the thickness of (5B) is made different, the depth of the potential can also be made different using the difference in impurity concentration of the semiconductor substrate without using the difference in the oxide film thickness. In this case, storage electrode (12B) and transfer electrode (12A)
) The thickness of the underlying insulating layer is the same, but instead a P-type thick conductive shallow region is formed under the transfer electrode (12A). This P-type head region can be formed, for example, by selective ion implantation.

The gate section (10) between each sensor part (1) and the corresponding shift register (2) is, for example,
A region (14) having the same conductivity type as the substrate (4) but having a higher impurity concentration is formed facing the main surface (4a), and an insulating layer (5), for example an insulating layer ( 5B)
is provided in an extended manner, and a gate electrode (15) is deposited thereon. The gate electrode (I5) of the gate part (10) corresponding to each sensor part (1) and the shift register (
2) The electrodes (13^) and (13B) of each transfer section (11)
) are formed by a common electrode, or are electrically connected to each other so that a common voltage is applied to them, as shown by the chain line a in FIG. ) and the transfer section (11), the impurity concentration of each section (10) or the thickness of the insulating layer is adjusted so that the minimum potential of each section is always shallow at the gate section even if the same voltage is applied to each electrode of the transfer section (11). shall be selected. Then, every other transfer unit (11) is connected in common, and terminals Lr1 and t-rZ are led out.

In addition, the overflow control section (8), for example, controls the base (
A region (16) having the same conductivity type as 4) but having a higher impurity concentration than this is formed facing the main surface (4a),
A control electrode (17) is deposited on this via an insulating layer (5).

The sensor part (1) is constructed by depositing a sensor electrode (18) thereon via a light-transmissive insulating layer (5). This sensor electrode (18) and the corresponding control electrode (17) of the overflow control section (8) may be constituted by a continuous common transparent electrode, or may be electrically connected to a terminal that applies a common voltage. , is derived.

In addition, each area (6), (7), (9), (14),
(16) is a well-known technique such as selective diffusion method,
It can be formed by ion implantation or the like. Also, electrode (15)
(12A) and (12B) can be formed by sequentially depositing polycrystalline silicon layers doped with impurities to have low resistance by chemical vapor deposition, and by oxidizing their surfaces, an insulating layer is formed. forming a sensor electrode (18) and an overflow control electrode (
17) can be formed by covering the entire surface with a transparent electrode.

Then, a light shielding layer (1) is placed on the part other than the sensor part (1).
9). This light-shielding layer (19) may be composed of, for example, an aluminum layer, and in this way, the light-shielding layer (19)
When the electrodes are made of a conductor, an insulating layer (5) is formed covering each electrode, and a light shielding layer (19) is applied thereon.

As described above, in the device of this example, a portion of each sensor (1
The sensor electrode (18) of ) and the control electrode (F) of the corresponding overflow control section (8) are electrically common, but the image electrode (18) and (17) are common. When a voltage is applied, the minimum potential between the sensor part (1) and the overflow control part (8) (in the illustrated example, the minimum potential is generated on the surface; in this case, the minimum potential is the surface potential. (equivalent), and
This potential difference is made to change depending on the applied voltage. In the above example, the surface concentration of the sensor part (1) is selected to be the concentration of the substrate (4), and the overflow control part (8)
In this case, the thickness of each insulation N (5) of the sensor part (1) and the overflow control part (8) is 3000 people. , the surface concentration of the sensor part (1) is 5X1014c
m-", and the control section (8) is set to 5XIO"cva.
-', the common applied voltage to the sensor electrode (18) and the control electrode (17), that is, the terminal, is also the same in the sensor part (1) and the control part (8) with respect to the applied voltage φ3 to the terminal. As shown in curves (20) and (21) in FIG. 5, the surface potentials ψ and ψ0 vary with the applied voltage φ3.
As the value increases, the difference between the two becomes larger. In the above example, the surface concentrations of the sensor part (1) and the control part (8) are selected so that there is a difference in their surface potentials. Control part (8)
The surface concentration of the electrode (18) and (
17) It is also possible to make the thicknesses of the underlying insulating layers different from each other, so that the thickness of the insulating layer in the sensor part (1) is selected to be smaller than that in the control part (8). With this configuration, as will be described in detail later, the difference in surface potential (ψ, −ψC
), that is, the control section (8) controls the sensor part (1) and the overflow drain region (9).
) by changing the height of the barrier between the sensor part (1)
Controls the amount of carrier overflow.

For convenience of later explanation, as shown in FIG. 2, some of the sensors (1) on each horizontal line are sequentially moved to S1. S! , S3...
・and the transfer section of the shift register (2) corresponding to each (
11) are T,,T,,T,..., and the electrodes of every other transfer section T+, T's, Ts... are connected to the terminal t, and the electrodes of every other transfer section T, Transfer section Tt, Ta
, T b . . . are connected to the terminal 1t.

Next, to explain the operation of this example device, in this case as well, during the vertical blanking period, signal charges corresponding to the amount of light received by the sensor part (1) are transferred to the corresponding transfer part of the vertical shift register (2). 11) Transfer (hereinafter referred to as read).

) and the terminals tr+ and 1. of the shift register (2). □, as shown in FIGS. 6A and B, a two-phase clock φ9. and φ9. is given, and during the horizontal blanking period, this signal charge is sequentially transferred to the adjacent transfer section in one direction, and the signal for each horizontal line is transferred to the horizontal shift register (3) shown in FIG. During a horizontal video period, signals for each horizontal line are read out from the terminals. FIGS. 7 to 9 are minimum potential diagrams of various parts in the cross section shown in FIG. 3, including the overflow drain region (9).

Each minimum potential of the overflow control section (8), the sensor part (1), the gate section (10), and the storage gate section (13B) is set to ψ4. ψ0. ψ1. ψ9. It is expressed as ψb, and the potential in each applied voltage state is shown with a suffix attached. FIG. 7 shows the light reception/accumulation mode, and in this light reception/accumulation state, a voltage that forms a deep potential well in the sensor part (1) is applied to the terminal ts, that is, a large positive voltage φ.

give. Then, time t of the vertical blanking period corresponds to the beginning of the odd-numbered field period.

Then, as shown in FIG. 6A and B, the shift register (2
) voltages φv1 and φV□ applied to terminals t□ and Lrt of
As well as the terminals with the required voltage applied as positive.

As shown in FIG. 6C, the voltage φ applied to the eighth
As shown in the minimum potential diagram in the figure, we set the potential ψ,I that makes the potential well of the sensor part (1) sufficiently shallow, and the storage part of the transfer part (11) corresponding to this sensor part (1) The potential ψb8 is set to sufficiently source a potential well. In this way, each sensor part S I + S R + S,...
The signal charges (carriers) generated and accumulated in accordance with the amount of light received are transferred to each transfer section T I, T z , T s .
The data is transferred, that is, read out, to the storage section .as shown by the arrow in FIG. Next, within this vertical blanking period, as shown in FIGS. 6A and 6B, for example, the voltage φ of the terminal t2, ! Terminal 1. is held at the required voltage of the above voltage. The voltage φv1 is lowered to, for example, 0■. In this way, every other transfer unit T I, T 3 ,
Each charge of T s... is transferred to every other transfer section T
, , T, , T, . . . and the charges of the two transfer parts are added. That is, sensor parts S+, Ss, Ss
Each signal charge of ... is adjacent to the sensor part St, S
,,S,... are superimposed. This charge is transferred to the horizontal shift register as usual during vertical and horizontal blanking periods, but in this example a gamma correction operation is performed during an appropriate number of selected horizontal blanking periods. That is, the terminal jr during the horizontal blanking period
The voltages applied to l and m are both low voltage OV, for example.
In the state of is relatively high at each time point L+ during the horizontal blanking period.
As shown in FIG. 6C, a gradually higher voltage φ83. φ, 2. φ8. ...That is, φ3I<φ32<φ8. ... is given, and as shown in FIG. 9, the potential ψ31. ψ51 ψ5. . . . and reduce the potential of the overflow control section (8) to ψ. .

Let ψC1 and ψc3. In this case, as explained with reference to FIG. 5, as the applied voltage is increased, the difference in potential between the sensor part and the overflow control section, that is, the potential barrier, is increased, so the amount of overflow is reduced. This operation will be explained in detail with reference to FIGS. 9 and 10, for example, when light with an intensity of I4 is incident. That is, when light with intensity I4 is incident, first, when φ, 4 is given to terminal t, the potential φ, 4 of the sensor part and the potential ψ of the overflow control part.
Charges equal to or greater than the charge amount 94 determined by the difference in c4 are discarded to the overflow drain, and the charge amount accumulated in a part of the sensor is saturated at q. Next, at a certain point in time tl during a certain horizontal blanking period, the terminal t1 has a relatively low potential φ1. is given, the potential of a part of the sensor φ3. Charges with an accumulated amount of 91 or more determined by the potential φcl of the overflow control section are removed to the overflow drain. Then, since the potential applied to the terminal t is again set to φs4, the intensity of the incident light I4
Again, the charge is the potential φ of the sensor part,
4 and the overflow control section, and the surplus charge amounting to 94 or more is discarded to the overflow drain. Next, at a time point 1g during another determined horizontal blanking period, the previous φ5. Potential φ, higher than ! As a result, the charge exceeding the accumulated amount Qt determined by the potential φ,2 of the sensor part and the potential φ of the overflow control section is removed to the overflow drain. Thereafter, the potential φ,4 is applied to the terminal again, the charge is accumulated, and at a point in time t during the third selected horizontal blanking period, a potential φ,3 higher than φ is applied to the terminal. Accordingly, charges with an accumulated amount of 98 or more are eliminated.

Thereafter, the potential φ,4 is applied to the terminal t again, so that charges are accumulated in accordance with the incident light and then read out at a point in time t4 during the vertical blanking period. Therefore, now the intensity of light ■ is i o < 1 + < I t <
Looking at the amount of charge q accumulated in the sensor part (1) at time ~t4 when light having the relationship I s < I m is received, at each time t as shown in FIG.
1. Charges 91 to 94 or more of the sensor part (1) determined by the values of ψ and -ψ at Lt, f, x, t, and a, respectively, are overflowed and removed, so the The charge amount is subjected to a power function curve, that is, gamma correction, as shown in FIG. That is, Fig. 10 and Fig. 1
In Figure 1, light with intensity less than ION! . The amount of charge accumulated in the sensor when is incident is shown by straight line 2I, and ■. 7
When light ■1 of intensity between and I is incident, the amount of charge accumulated in the sensor is a straight line i! The same applies hereafter.

Then, gamma correction can be performed on the next even-numbered field by performing the same operation, but in this even-numbered field, as shown in Figure 6, the vertical After reading from each sensor part SI+Sz, S3,... to the transfer part Tl1T, T,... of the shift register (2) during the blanking period, contrary to the case of the odd-numbered field described above, With the voltage at terminal t maintained at a predetermined positive voltage,
For example, when the terminal 11 is set to O■, the sensor portions St, S1 . S
4... are transferred to other adjacent sensor parts S, , S, , S,... which are different from the combination in the odd field, respectively.
... so that it can be added with... That is, in even fields, Sl and St, Ss and S, SS and S,...
. . constitutes one pixel signal, and in odd fields, other combinations of S2, Si, and S4
and Ss, Si and S, . . . form one pixel signal.

In this way, one screen (one frame) is formed by two fields, and an effect similar to interlaced scanning is obtained.

In the above configuration, in order to adjust the sensitivity, the width of the overflow control section (8) is kept sufficiently small, and the width of the 12th
As shown in the figure, the bias of the overflow drain region (9) is deepened, and its potential influences the control section (8), lowering this barrier and allowing the carriers in the sensor part (1) to escape to the region (9). This can be done by tightening it. That is, when a large bias is applied to the overflow drain, signal charges generated in the sensor region flow into the overflow drain and are not accumulated. Therefore, the light reception accumulation period can be shortened depending on the amount of light received.

As described above, according to this example, gamma correction can be performed without providing an electrically independent electrode in the overflow control section, which reduces the complexity and reliability of manufacturing due to the complicated electrode structure. decline.

It is possible to avoid problems such as a decrease in yield, and the benefits are great in practical use.

Furthermore, with the above configuration, the charge from some of the sensors s, s, ss, . . . is read out at the beginning of each field, so the problem of afterimages can be solved. That is,
When reading out the electric charge of a part of every other sensor in each field as in the conventional case, light reception occurs in a part of each sensor even during the field period in which part of every other sensor is read out. Since two fields of light are received each, the problem of afterimages occurs, but this problem is solved by the device of this embodiment described above.

In the above example, the sensor electrode is shared and a part of the signal charge of each sensor is read out in each field. l+S :l+S
s...+S! l S at S b...
It is also possible to divide .

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of an interline transfer type solid-state imaging device, Fig. 2 is a top view of the main parts of the device of the present invention, and Fig. 3
Figure 4 and Figure 4 are sectional views on the ■-■ line and IV-IV cotton line respectively, Figure 5 is a curve diagram showing the relationship between the minimum potential and the applied voltage of the sensor part and the overflow control section, and Figure 6 is the operation. 7 to 9 are potential diagrams showing each mode of the device of the present invention, and FIG. 10 shows the accumulated charge in a part of the sensor at each point in time when the light intensity is changed. Figure shown, 1st
FIG. 1 is a gamma correction curve diagram, and FIG. 12 is a minimum potential diagram in automatic sensitivity adjustment mode. (1), S, St, Sz... are part of the sensor, (2)
is a vertical shift register, (3) is a horizontal shift register,
(4) is a semiconductor substrate, (5) is an insulating layer, (7) is a channel stopper region, (8) is an overflow control section,
(9) is an overflow drain region, (10) is a gate portion, and (11). T + , T t , T s ... are transfer parts of shift register (2), (13A) and (13B) are transfer electrodes, (15) is a gate electrode, (17) is an overflow control electrode, (18) ) is the sensor electrode.

Claims (1)

[Claims] A plurality of sensors arranged in a matrix in the horizontal and vertical directions, and a plurality of vertical shifts in which the charges accumulated in the sensors are read out every vertical period of a television signal and transferred in the vertical direction. A register, a horizontal shift register that receives the charge transferred by the vertical shift register and transfers the charge horizontally, and an overflow drain section that absorbs a predetermined amount or more of the charge generated by the sensor. In an interline transfer solid-state imaging device having an overflow drain section whose predetermined amount can be controlled by an electric signal, in one of two consecutive vertical periods, According to the first combination of sensors,
The charges of two vertically adjacent sensors are combined and transferred by the vertical shift register, and in the other of the two consecutive vertical periods, the charges of the two sensors arranged vertically are combined and transferred by the vertical shift register. The electric charges of two vertically adjacent sensors are combined according to a second combination different from the first combination and transferred by the vertical shift register, and in each vertical period, the electric charges are combined and transferred by the vertical shift register during the predetermined horizontal blanking period. A solid-state imaging device, characterized in that an electrical signal for controlling quantification is supplied to control the amount of charge accumulated in the sensor.