JP2000101061A - Solid-state image sensing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid-state image sensing device with a full frame transfer(FFT) or frame transfer(FT) type CCD capable of a high speed charge transfer as a surface incidence type. SOLUTION: Light receiving parts 1 of an FFT type CCD or FT type CCD have polycrystalline Si transfer electrodes having a high wiring resistance, compared with a metal one and metal-made or metal silicide-made sub-electrodes 11-19 separate from them which are disposed obliquely to the transfer electrodes or otherwise in a different constitution or shape from the transfer electrodes, so as to essentially minimize the area covered with the transfer electrodes impermeable to lights. This makes an effective light reception/image sensing compatible with a high speed charge transfer with voltages fed to the transfer electrodes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a full frame transfer type (FFT type) CCD or a frame transfer type (FFT type) CCD.
The present invention relates to a solid-state imaging device having a (T-type) CCD.

[0002]

2. Description of the Related Art FIG. 11 is a schematic structural view of a conventional FFT type CCD viewed from the surface when driven by a three-phase clock. The FFT type CCD includes a light receiving unit 1 and an output unit 3. The hatched portion of the light receiving section 1 indicates a unit pixel 1a, and the horizontal direction of the light receiving section 1 corresponds to m columns H1 to Hm whose vertical direction is the longitudinal direction, and the vertical direction is the horizontal direction. Divided into n rows V1 to Vn as directions,
The light receiving section 1 is composed of mxn unit pixels 1a. The output unit 3 includes a horizontal shift register 3a and an amplifier unit 3b.

FIG. 12 is a schematic structural view of a conventional FT type CCD viewed from the surface when driven by a three-phase clock.
Shown in The structure of this FT type CCD is almost FFT type CCD.
The configuration is the same as that described above, but includes a light receiving unit 1 and an output unit 3, and a storage unit 2 used for storing and transferring electric charges.

In these FFT type and FT type CCDs, a transfer electrode (not shown) for performing charge transfer in the light receiving section 1 and the storage section 2 is provided on the front side of the light receiving section 1 and the storage section 2. The horizontal direction (parallel to the longitudinal direction of each row) is set as its longitudinal direction so as to cover the entirety, and three transfer electrodes (in the case of three-phase clock drive) arranged in parallel per unit pixel are arranged vertically. A shift register is formed, and the vertical shift register includes the light receiving unit 1 and the storage unit 2.
Is configured. That is, three transfer electrodes are arranged in each row in a state where the longitudinal direction is orthogonal to the configuration direction of the vertical shift register. Each transfer electrode has a three-phase transfer voltage P1,
P2 and P3 are applied, respectively, and the charge transfer operation of the vertical shift register is controlled by these voltages. Note that the directions of charge transfer in the vertical shift register and the horizontal shift register are indicated by arrows in FIGS.

Conventionally, light-transmitting polycrystalline silicon (polysilicon) has been used as a transfer electrode for forming such a vertical shift register of a CCD. Has a problem that the resistance is higher than that of metal.

FIG. 13 shows an equivalent circuit of a wiring made of polycrystalline silicon for a vertical shift register. When high-speed charge transfer is performed in a vertical shift register by an FT type or FFT type CCD, the charge transfer speed is limited by the wiring resistance r of the polycrystalline silicon. Also, the clock signal due to the transfer voltage applied from the outside becomes dull according to the length of the wiring, the waveform is distorted depending on the location, and the rise time differs, resulting in the transfer efficiency of the CCD (charge transfer between potential wells). Ratio) deteriorates.

To solve such a problem, see, for example,
JP-A-3-46763 and JP-A-6-77461 disclose a CC using a low-resistance transfer electrode having an intermediate layer, a multilayer structure, or a backing structure of metal or metal silicide.
D is described.

[0008]

However, a transfer electrode using a metal or a metal silicide as a layer or a backing, or a transfer electrode made of metal as described above does not transmit light. It can be used only for the light receiving part and the storage part of the storage part or the interline type (IL type) CCD, and cannot be applied to the light receiving part of the FFT type and FT type CCD.

On the other hand, in the FFT type and FT type CCD disclosed in Japanese Patent Application Laid-Open No. 6-77461, it is possible to use a transfer electrode using metal or metal silicide for the light receiving section by making the CCD backside illuminated. Has been described. A back-illuminated CCD is a type of CCD that uses a thin substrate, while a normal CCD uses a thin substrate to capture an image by receiving light that has been incident from the front and transmitted through a transfer electrode such as polycrystalline silicon.
Is formed and receives light transmitted through the substrate from the rear surface and receives light to perform imaging.Therefore, light is incident and received without being affected by the transfer electrode installed on the front surface side. Can be. However, in back-illuminated CCDs, the substrate must be processed to a sufficiently small thickness, which complicates the manufacturing process and increases the price. In addition, the thinness of the substrate makes the strength low and difficult to handle. There is a problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has been made in consideration of the above problems. An FFT type or FT type CCD capable of receiving light and imaging by receiving light from the surface and capable of performing high-speed and highly efficient charge transfer. To provide a solid-state imaging device according to the present invention.

[0011]

In order to achieve the above object, a solid-state image pickup device according to the present invention comprises a plurality of parts which divide a horizontal direction formed on a substrate including a p-type semiconductor layer and an n-type semiconductor layer. Has a matrix-shaped pixel structure composed of a plurality of columns and a plurality of rows dividing the vertical direction, and a light receiving unit for receiving and capturing an incident light image of an imaging target; A plurality of transfer electrodes, each of which is provided with a horizontal direction parallel to the longitudinal direction of each row of the unit as a longitudinal direction, and a transfer voltage is applied to perform charge transfer in the light receiving unit. Or a solid-state imaging device configured using one of the frame transfer type CCDs, each of which is disposed above a plurality of transfer electrodes, a transfer voltage is applied, and a light receiving portion of the plurality of transfer electrodes is Each installed in two rows are connected to corresponding transfer electrodes even without, and further comprising a plurality of auxiliary electrodes each consisting of an auxiliary transfer voltage metal or metal silicide applying and supplies.

[0012] Further, the plurality of auxiliary electrodes may be respectively provided with a direction oblique to the plurality of transfer electrodes as a longitudinal direction.

As described above, apart from the transfer electrodes made of polycrystalline silicon, auxiliary electrodes made of metal or metal silicide used for applying and supplying a voltage to those transfer electrodes are provided in a plurality of rows of the light receiving section. By installing and configuring so as to be connected to a certain corresponding transfer electrode, the layer or backing structure made of metal or metal silicide was integrated with the transfer electrode, whereas the transfer electrode had a different structure.
It becomes an auxiliary electrode having a shape. Therefore, while the transfer electrode is installed so as to cover the entire light receiving section, the area covering the light receiving section is minimized, and efficient light receiving / imaging and voltage application to the transfer electrode are performed. It is possible to configure auxiliary electrodes so that supply can be performed at the same time,
As a result, a solid-state imaging device using an FFT type or FT type CCD, in which light is incident from the surface to perform light reception and imaging, and capable of high-speed and highly efficient charge transfer is realized.

As a structure of such an auxiliary electrode, for example, there is a method in which the auxiliary electrode is installed obliquely with respect to the transfer electrode.

Further, one of the full-frame transfer type and the frame transfer type CCD is configured so that charge transfer is performed by an N-phase transfer voltage, and the plurality of auxiliary electrodes have N or less auxiliary electrodes. It is characterized in that an auxiliary electrode portion is constituted by a set of electrodes, and a plurality of auxiliary electrode portions are provided.

Further, the auxiliary electrode section is characterized in that the auxiliary electrode section is configured as a set of N auxiliary electrodes to which N-phase transfer voltages are respectively applied.

The above-mentioned auxiliary electrodes are formed with an auxiliary electrode portion by the number of N or less for driving by the N-phase transfer voltage (N-phase driving), and a plurality of the auxiliary electrode portions are provided by a repetitive structure. In addition, the transfer voltage of each phase can be efficiently applied and supplied. As an efficient configuration of such an auxiliary electrode structure, for example, one auxiliary electrode portion is formed by N auxiliary electrodes corresponding to an N-phase transfer voltage, and the auxiliary electrode structure is formed by repeating the auxiliary electrode portion. Can be configured.

In addition, for example, in the case of three-phase driving, a method of forming an auxiliary electrode portion with two auxiliary electrodes corresponding to two-phase transfer voltages in each of the auxiliary electrode portions may be employed. , A solid-state imaging device with improved operation speed and efficiency.

Further, the present invention is characterized in that the area covered by the plurality of auxiliary electrodes is equal for each column of the light receiving section, and the area covered by the plurality of auxiliary electrodes is equal for each row of the light receiving section.

For example, an object on a belt conveyor,
As a method for capturing an image of an object moving at a constant speed, a time delay and TDI (TDI) that accumulates charges while transferring the charges accumulated in the light receiving unit at a speed corresponding to the moving speed of the object.
Integration) driving method is used, but when imaging is performed by applying the TDI driving method to the solid-state imaging device having the above configuration in which the area covered by the auxiliary electrode in each column and each row is the same, each position of the object is It is possible to perform uniform imaging over the entire optical image with the sensitivity of charge accumulation / imaging corresponding to the above.

Further, each row of the light receiving section has an open gate which is an opening in one of the transfer electrodes in a region between the auxiliary electrodes passing above the substrate, and a substrate corresponding to the open gate. Wherein a diffusion layer made of a p-type semiconductor is provided in a surface side region in the n-type semiconductor layer.

In particular, in inspection of a semiconductor wafer, etc.,
For example, a CCD having sensitivity to ultraviolet light having a wavelength of 400 nm or less is required. However, in polycrystalline silicon, there is a problem in that sensitivity to blue or ultraviolet light due to absorption of short-wavelength light is reduced. On the other hand, in the light receiving portion, a part of the pixel where the auxiliary electrode does not exist is an opening where the transfer electrode made of polycrystalline silicon is not arranged, and a diffusion layer is formed in order to fix the potential of the pixel in the opening. By having the open gate provided, a solid-state imaging device with improved sensitivity to ultraviolet light can be provided.

The compatibility between an electrode structure using a metal or the like for high-speed charge transfer and an open gate structure is as follows.
This is only possible with the electrode structure according to the invention. This realizes a solid-state imaging device that operates at high speed and has high sensitivity to ultraviolet light.

Also, this open gate is configured such that the area of the open gate is equal to each column of the light receiving section and the area of the open gate is equal to each row of the light receiving section. , TD
In the imaging by the I-drive method, it is possible to perform uniform imaging over the entire optical image in which the sensitivity of charge accumulation and imaging is captured.

Further, the transfer voltage applied to each of the plurality of transfer electrodes and the plurality of auxiliary electrodes is changed at a speed corresponding to the moving speed of the object to be picked up. A configuration may further be provided that further includes a charge transfer control unit that controls by a TDI driving method that performs imaging. With such a configuration, the above-described TD
A fixed imaging device that performs imaging by the I drive method can be provided.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a solid-state imaging device according to the present invention will be described below in detail with reference to the drawings.
In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description. Also, the dimensional ratios in the drawings do not always match those described.

FIG. 1 is a schematic configuration diagram schematically showing a wiring configuration of auxiliary electrodes in one embodiment of a three-phase drive of a solid-state imaging device using an FFT type CCD according to the present invention.

The pixel structure and the like are the same as those shown in FIG. 11. The light receiving section 1 has m horizontal rows H1 to Hm with the vertical direction as the longitudinal direction, and the light receiving section 1 has the vertical direction.
It is divided into n rows V1 to Vn whose longitudinal direction is the horizontal direction, and is composed of m × n unit pixels. Also,
The output unit 3 includes a horizontal shift register 3a and an amplifier unit 3b.
It is constituted by.

A light-transmissive transfer electrode (not shown), preferably made of polycrystalline silicon, is
And covers the entire light receiving unit 1 on the front side of each row Vj (j = 1
To n), three-phase transfer voltages P1, P2 and P3 each having a different phase (time dependency) are applied to each row in a direction parallel to the longitudinal direction (horizontal direction). You. On the other hand, in the present embodiment, the auxiliary electrode portions 11 to 19 made of metal, preferably aluminum, having a low wiring resistance are provided with respect to the transfer electrodes and, therefore, the light receiving portion 1.
Are arranged obliquely upward to the right with respect to each column and each row.

Each of these has three auxiliary electrodes, for example, the auxiliary electrode section 11 has three auxiliary electrodes 11a, 11b and 1
1c, a transfer voltage P1 is applied to the auxiliary electrode 11a, a transfer voltage P2 is applied to the auxiliary electrode 11b, and a transfer voltage P3 is applied to the auxiliary electrode 11c. As a result, the transfer electrodes are connected to the corresponding transfer electrodes, and a predetermined transfer voltage is supplied to those transfer electrodes. The same applies to the configuration and connection of the other auxiliary electrode portions 12 to 19.

These auxiliary electrode portions 11 to 19 are
The light receiving unit 1 is configured and installed with a repetitive structure at equal installation intervals over the entire light receiving unit 1. With such a repetitive structure, a transfer voltage can be efficiently and uniformly supplied to each transfer electrode. The transfer voltages P1 to P3 applied to these transfer electrodes and auxiliary electrodes are controlled by the charge transfer control unit 4.

As in the case of the conventional layer structure or backing structure, when these auxiliary electrodes are arranged in parallel to the transfer electrodes, that is, so as to pass only through the upper part of a single row, it is necessary for each transfer electrode. In order to supply a high transfer voltage, it is necessary to install an auxiliary electrode made of metal or the like that does not transmit light to the entire light receiving unit 1 after all. Can not be used as

On the other hand, the auxiliary electrode is not parallel to the transfer electrode, for example, it is oblique to the transfer electrode as in the present embodiment, that is, the auxiliary electrode is configured and installed so as to pass over a plurality of rows. Thereby, it is possible to configure so that the light-receiving area that is not covered with the auxiliary electrode is sufficiently large.

In particular, as a method of imaging an object which is moving at a constant speed, such as an object on a belt conveyor, for example, each pixel of the light receiving section 1 is moved at a speed corresponding to the moving speed of the object. (Time Delay and Integration) that continuously stores and captures charges while transferring charges (charge packets) accumulated in a potential well formed by a transfer voltage applied to a transfer electrode
A driving method is used. Such a driving method is realized by controlling the transfer voltage by the charge transfer control unit 4 described above.

According to such a method, a specific charge packet of the light-receiving unit 1 can always perform a blur-free imaging corresponding to a specific position of a moving object to be imaged. In particular, in such an imaging method, the area covered by the auxiliary electrode, which is an insensitive region of imaging, is determined by each column Hi (i =
1 to m) and for each row Vj (j = 1 to n).

In this embodiment, the horizontal positions of the upper and lower ends of the corresponding auxiliary electrodes, such as the upper end 12ah of the auxiliary electrode 12a and the lower end 17ah of the auxiliary electrode 17a, coincide with each other. By corresponding, for each row Vj, for example, the auxiliary electrode 12a
The above condition, that is, the area covered by the auxiliary electrode is equal to each column and each row by matching and corresponding the vertical position between the left end and the right end of the corresponding auxiliary electrode such as the left end 12av of the auxiliary electrode and the right end 16av of the auxiliary electrode 16a. And the same configuration is realized. With this configuration, T
When imaging is performed by applying the DI driving method, it is possible to make the time and the rate at which the moving charge packets on the light receiving unit 1 corresponding to each position of the object pass through the insensitive area by the auxiliary electrode, Therefore, it is possible to perform imaging in which the imaging sensitivity is uniform for the entire optical image to be imaged.

FIG. 2 shows an FFT in the three-phase drive shown in FIG.
FIG. 3 is a configuration diagram showing, in an enlarged manner, a part of an electrode structure of a transfer electrode and an auxiliary electrode on a surface of a light receiving unit 1 of the type CCD. FIG. 3 is a cross-sectional view of the electrode structure shown in FIG.
It is I arrow sectional drawing. The transfer electrodes provided in the direction orthogonal to the configuration direction of the vertical shift register have adjacent transfer electrodes and both end portions (upper and lower ends parallel to the longitudinal direction) shown in FIG. 3, for example. Although they are partially overlapped as shown in FIG.
In order to clarify the configuration and connection relationship of the electrode structure, overlapping portions of the transfer electrodes are not shown. Regarding the scale of the figure, the scales in the vertical direction and the horizontal direction do not always match in FIG. In FIG. 3, the electrode structure is shown on a different scale from that of FIG. 2 for easy viewing.

Each transfer electrode is made of polycrystalline silicon. For example, three covering portions of the transfer electrodes 111a, 111b and 111c correspond to one row Vj of the light receiving section.
In addition, each column Hi of the light receiving sections is surrounded by two adjacent vertical dotted lines in FIG. 2 and is shown as an isolation region 1b (a reference numeral 1b denotes one of them) arranged at regular intervals. Only attached)
Thus, each unit pixel of the light receiving section is formed. Each transfer electrode includes, for example, transfer electrodes 111a, 111b and 11
3c, three-phase transfer voltages P1, P2, and P3 having different phases are respectively applied, and a potential well formed in each pixel of the light receiving portion and a stored charge packet The position is moved over time, causing a vertical transfer of charge. The same applies to other transfer electrodes below the transfer electrodes 112a to 112c.

Each of the transfer electrodes made of polycrystalline silicon has a higher wiring resistance than metals and the like. However, in order to surely supply a transfer voltage to them and realize a high transfer speed, as described above, A wiring made of a metal, preferably aluminum, auxiliary electrode having a low wiring resistance is installed obliquely upward to the right and connected to the transfer electrode.

In FIG. 2, three parallel auxiliary electrodes 110a, 110b and 110 corresponding to three-phase driving are provided.
The auxiliary electrode portion 110 is formed as a set of the sub-electrodes c, and the auxiliary electrode portion 110a is disposed obliquely upward to the right with respect to the transfer electrode, and the auxiliary electrode 110a to which the transfer voltage P1 is applied is connected to the transfer electrode 112a at the connection portion 112e, At the transfer electrode 113a and at the connection 114e at the transfer electrode 11a.
4a. Similarly, the auxiliary electrode 110b to which the transfer voltage P2 is applied is connected to the transfer electrode 112b at the connection portion 112f and to the transfer electrode 11b at the connection portion 113f.
3b and the transfer electrode 114b at the connection 114f.
The auxiliary electrode 110c to which the transfer voltage P3 is applied is connected to the transfer electrode 112c at the connection portion 112g.
The connection portion 113g is connected to the transfer electrode 113c, and the connection portion 114g is connected to the transfer electrode 114c.

By applying / supplying the transfer voltage by connecting the wiring with the auxiliary electrode and the transfer electrode in this manner, the drive clock of each phase is supplied to each transfer electrode at high speed without any waveform distortion. Thus, charge transfer with high transfer speed and high transfer efficiency can be realized.

In the present embodiment, in the vertical direction, the auxiliary electrode portion has a repetitive structure in which five rows of pixels, that is, fifteen transfer electrodes (for example, 111a to 115c) are arranged at intervals. In FIG. 2, the auxiliary electrode 120, which is the next set of the auxiliary electrode unit 110 including the auxiliary electrodes 110a to 110c described above, is provided.
A part of the auxiliary electrode unit 120 including the parts a to 120c is shown below. In the horizontal direction, FIG. 2 shows only six columns of pixels. However, the connection portions of the auxiliary electrodes are provided at equal intervals, and even in the pixels other than the columns shown, the voltage due to the sequential connection with the transfer electrode is provided. Is supplied.

Of the transfer electrodes, the electrode to which the transfer voltage P3 is applied, in the figure, the transfer electrodes 111c and 112
c, 113c, 114c, 115c and 121c are:
An open gate, which is an opening where a transfer electrode made of polycrystalline silicon is not provided, is provided in a pixel portion where the auxiliary electrode is not disposed above the auxiliary electrode. When a transfer electrode made of polycrystalline silicon is used, there is a problem in that sensitivity to ultraviolet light due to absorption of short-wavelength light, for example, ultraviolet light having a wavelength of 400 nm or less is reduced. In order to solve such a problem, a structure having an open gate in which no transfer electrode exists as described above, the open gate region has a sufficient sensitivity to ultraviolet light, and therefore, a CCD with improved sensitivity to ultraviolet light. It can be.

The open gate structure according to the present embodiment has the above-described transfer electrodes 111c, 112c, 113c,
For 114c, 115c, and 121c, six rows of openings are provided in regions between adjacent auxiliary electrode portions. FIG. 2 shows the entire opening of the transfer electrode 115c,
Other transfer electrodes 111c, 112c, 113c, 1
For 14c and 121c, a part on the right or left side of the opening is shown.

When the open gate is provided at a position including the pixel portion where the auxiliary electrode is present on the upper portion, the transfer electrode serving as the transfer gate does not exist between the open gate and the auxiliary electrode is effectively disposed. Function as a transfer gate at the same time, there is a possibility that charge transfer failure may occur. Therefore, as described above, it is desirable that the open gate is provided only in the pixel portion where the auxiliary electrode does not exist in that region. Further, in the present embodiment, in order to realize imaging with uniform wavelength sensitivity when the imaging method by the TDI driving method is performed, the area of the open gate region is set to each column Hi and each row similarly to the auxiliary electrode. These open gate structures are configured and installed to be equal to Vj.

FIG. 3 is a sectional view taken along the line II of the electrode structure shown in FIG. However, FIG. 3 shows only a region corresponding to the transfer electrodes 112c to 122a in the cross section. The transfer electrodes and auxiliary electrodes shown in FIG. 2 are formed on a semiconductor substrate 20 having a pn junction including a p-layer 22 as a p-type semiconductor layer and an n-layer 23 as an n-type semiconductor layer via an oxide film 21. It is formed. The transfer electrodes whose regions partially overlap each other are provided so as to be electrically insulated by an insulating film 25 which is an oxide film.

The auxiliary electrodes 110a to 110c are
By being separated by 5, they are arranged in a state where they are not directly in contact with or connected to each transfer electrode. FIG. 3 shows the connection between the auxiliary electrodes 110a to 110c and the transfer electrodes 113a to 113c. That is, the auxiliary electrodes 110a to 110c and the transfer electrode 113a
, Made of metal, preferably aluminum, provided so as to penetrate the insulating film 25 between
3e to 113g, the two are connected to each other, whereby the auxiliary electrodes 110a to 110c
13a to 113c, the corresponding transfer voltages P1 to P
3 are applied and supplied.

Also, the open gate region where the transfer electrode is not provided (in FIG. 3, the transfer electrodes 114c, 115
Open gates corresponding to the opening portions c and 121c are shown), and a diffusion layer 24 made of a p-type semiconductor layer is formed in an upper region facing the oxide film 21 in the n-layer 23. By forming such a diffusion layer 24 and fixing its potential (for example, to the substrate potential) and changing the relative potential with respect to other transfer electrodes, these open gates having no transfer electrodes are provided. Also in the region, the transfer of electric charge is realized.

The auxiliary electrode having such a configuration can be similarly applied to a CCD driven by a driving clock other than the three-phase driving. FIG. 4 is a configuration diagram showing a part of the electrode structure of such an FFT type CCD driven by four phases in an enlarged manner. FIG. 5 is a cross-sectional view taken along the line II-II of the electrode structure shown in FIG. However, FIG. 5 shows only a region corresponding to the transfer electrodes 111d to 115c in the cross section.

The transfer electrodes made of polycrystalline silicon are, for example, transfer electrodes 111a, 111b, 111c and 111
The four covered portions of d correspond to one row Vj of the light receiving section. Each transfer electrode includes, for example, transfer electrodes 111a to 111a to
111d, four-phase transfer voltages P1 to P having different phases
4 are applied to transfer charges. The same applies to other transfer electrodes below the transfer electrodes 112a to 112d.

For these transfer electrodes, four parallel auxiliary electrodes 110a and 110 corresponding to the four-phase driving are provided.
b, 110c and 110d as one set and the auxiliary electrode portion 11
0, the auxiliary electrode 110a, which is installed obliquely upward to the right with respect to the transfer electrode, and to which the transfer voltage P1 is applied,
In the connection part 112e, the connection part 1 is connected to the transfer electrode 112a.
13e, the transfer electrode 113a and the connection 114
At e, it is connected to the transfer electrode 114a. Similarly, the auxiliary electrode 110b to which the transfer voltage P2 is applied is connected to the transfer electrode 112b at the connection 112f by the connection 11
3f, the transfer electrode 113b and the connection portion 114f
Are connected to the transfer electrode 114b, and the auxiliary electrode 110c to which the transfer voltage P3 is applied is connected to the transfer electrode 112c at the connection 112g, to the transfer electrode 113c at the connection 113g, and to the transfer electrode 113c at the connection 114g.
14c, the auxiliary electrode 110d to which the transfer voltage P4 is applied is connected to the transfer electrode 1
12d, the transfer electrode 113d at the connection portion 113h.
And at a connecting portion 114h to the transfer electrode 114d.

In this embodiment, in the vertical direction, the auxiliary electrode portion has a repetitive structure in which five rows of pixels, that is, twenty transfer electrodes (for example, 111a to 115d) are arranged at intervals. In FIG. 4, the auxiliary electrode 120, which is the next set of the auxiliary electrode unit 110 including the auxiliary electrodes 110a to 110d described above, is provided.
A part of the auxiliary electrode part 120 including a to 120d is shown below. In the horizontal direction, FIG. 4 shows only six columns of pixels. However, the connection portions of the auxiliary electrodes are provided at equal intervals, and even in the pixels other than the columns shown in FIG. Is supplied.

The electrodes to which the transfer voltage P1 is applied, in the figure, the transfer electrodes 111a, 112a, 11
Each of 3a, 114a, 115a and 121a has an open gate composed of four rows of openings provided in a region between adjacent auxiliary electrode portions, thereby improving the sensitivity to ultraviolet light. I have. Note that the area of the auxiliary electrode and the area of the open gate are configured to be equal for each column and each row, the method of forming each electrode on the substrate, the formation of the diffusion layer 24 in the area of the open gate,
This is the same as in the embodiment using three-phase driving.

FIG. 6 is a configuration diagram showing, in an enlarged manner, a part of the electrode structure of an FFT type CCD driven by two phases. FIG. 7 is a sectional view of the electrode structure shown in FIG.
It is II arrow sectional drawing. However, FIG. 7 shows only a region corresponding to the transfer electrodes 111d to 115c in the cross section.

In the two-phase drive, when the same electrode / substrate structure as in the above-described three-phase or four-phase drive is used,
The charge transfer direction cannot be determined in one direction, so that efficient charge transfer cannot be performed. Therefore, the electrode / substrate structure in this embodiment is slightly different from the three-phase or four-phase drive embodiment.

The transfer electrodes made of polycrystalline silicon are, for example, transfer electrodes 111a, 111b, 111c and 111
The four covered portions of d correspond to one row Vj of the light receiving section. The transfer electrodes 111a and 111b, 111c and 111d form a pair, and each of the transfer electrodes has a two-phase transfer voltage P having a different phase.
The transfer voltage P1 is applied to the transfer electrodes 111a and 111b, and the transfer voltage P1 is applied to the transfer electrodes 111c and 111d.
2 are applied to transfer the electric charge.

For these transfer electrodes, two auxiliary electrodes 110a and 110 parallel to each other corresponding to the two-phase driving.
The auxiliary electrode unit 110 is formed as a set of b, and the auxiliary electrode unit 110a is installed obliquely to the right with respect to the transfer electrode, and the auxiliary electrode 110a to which the transfer voltage P1 is applied is connected to the transfer electrodes 112a and 112b at the connection unit 112e. In the portion 113e, the transfer electrodes 113a and 113b are connected to the connection portion 11e.
At 4e, they are connected to the transfer electrodes 114a and 114b. Similarly, the auxiliary electrode 1 to which the transfer voltage P2 is applied
10b are connected to the transfer electrodes 112c and 112d at the connection 112f, and are transferred to the transfer electrode 113 at the connection 113f.
c and 113d, and at the connection 114f to the transfer electrodes 114c and 114d.

In the present embodiment, the vertical direction has a repetitive structure in which five rows of pixels, that is, twenty transfer electrodes (for example, 111a to 115d) are arranged at intervals. In FIG. 6, the auxiliary electrode 12 which is the next set of the auxiliary electrode portion 110 including the above-described auxiliary electrodes 110a and 110b is provided.
A part of the auxiliary electrode portion 120 composed of Oa and 120b is shown below. In the horizontal direction, FIG. 6 shows only six columns of pixels. However, the connection portions of the auxiliary electrodes are provided at equal intervals. Is supplied.

The electrodes to which the transfer voltage P1 is applied, in the figure, the transfer electrodes 111a and 111b, 1
12a and 112b, 113a and 113b, 114a
And 114b, 115a and 115b, 121a and 1
21b has an open gate formed of an opening portion for each of four rows provided in a region between adjacent auxiliary electrode portions, thereby improving the sensitivity to ultraviolet light. The configuration of the areas of the auxiliary electrode and the open gate region for each column and each row is the same as in the embodiment using the three-phase and four-phase driving.

FIG. 7 is a sectional view of the electrode structure shown in FIG.
It is arrow sectional drawing. Semiconductor substrate 20 in the present embodiment
Is composed of a p layer 22 and a layer composed of an n ⁻ layer 23a and an n layer 23b joined to the p layer 22. FIG.
The transfer electrodes and auxiliary electrodes shown in FIG.
0 is formed via an oxide film 21. The transfer electrodes whose regions partially overlap each other are provided so as to be electrically insulated by an insulating film 25 which is an oxide film.

The auxiliary electrodes 110a and 110b are arranged so as not to be directly in contact with or connected to each transfer electrode by being separated by the insulating film 25. FIG. 7 shows auxiliary electrodes 110a and transfer electrodes 112a and 112a.
The connection with b is shown. That is, the auxiliary electrode 110
and insulating film 2 between transfer electrodes 112a and 112b
5 are connected to each other by a connecting portion 112e made of metal, preferably made of aluminum, provided so as to penetrate through the transfer electrode 112 from the auxiliary electrode 110a.
Transfer voltage P1 is supplied to a and 112b.
In the present embodiment, for example, the auxiliary electrode 110a
Since the connection between the transfer electrodes 112a and 112b and the connection between the auxiliary electrode 110b and the transfer electrodes 112c and 112d are performed in different columns, in the cross-sectional view shown in FIG. Is not shown.

[0062] the n ^- layer 23a and the n-layer 23b structure is provided to be corresponding to the structure of transfer electrodes. For example, regarding the transfer electrodes 112a to 112d, the transfer electrode 1
Below the layers 12a and 112c are n ^- layers 23a,
An n layer 23b is formed below the transfer electrodes 112b and 112d, respectively. For the other transfer electrode portions, the n ^- layer 23a and the n layer 23b
Are formed alternately. With such a structure, the depths of potential wells formed by two adjacent transfer electrodes to which the same voltage is applied, for example, the transfer electrodes 112a and 112b, are set to be different from each other, and the charge transfer therebetween is performed. Has been realized.

That is, when the same transfer voltage is applied to the n ⁻ layer 23a and the n layer 23b from the transfer electrode,
it is n of the n-layer 23b ^- as compared to the layer 23a is the depth of the potential well becomes deeper, charge the n ^- are transferred to the n layer 23b from the layer 23a. Such n ^- layers 23a and n
The charge is transferred in one direction in the vertical direction by the charge transfer in one direction by the layer 23b and the charge transfer by the change of the two-phase transfer voltages P1 and P2 as in the case of the three-phase and four-phase driving. You.

The electrode structure using the auxiliary electrode is the above-described one in which N auxiliary electrodes and a repetitive structure thereof are provided for N-phase driving (N = 2, 3, 4). It is also possible to apply a repeating structure of two auxiliary electrodes to a structure, for example, N-phase driving (where N is 3 or more).

FIG. 8 shows an embodiment of a three-phase drive FFT type CCD in which two auxiliary electrodes are formed as one set. In the present embodiment, each of the auxiliary electrode units has a transfer electrode (for example, 111c) having an open gate to which the transfer voltage P3 is applied, and two other transfer electrodes (for example, 111a) to which the transfer voltages P1 and P2 are applied. And 111b), two auxiliary electrodes for supplying a transfer voltage to two transfer electrodes, one of the electrodes. In FIG. 8, some rows are further omitted as appropriate to show the repeating structure of the auxiliary electrode. However, the configuration of the transfer electrode, the period of the repeating structure of the auxiliary electrode portion, and the like in this embodiment are not shown. , Are the same as those shown in FIG.

The auxiliary electrode section 110 includes an auxiliary electrode 110a to which the transfer voltage P1 is applied and an auxiliary electrode 110c to which the transfer voltage P3 is applied. The auxiliary electrode 110a to which the transfer voltage P1 is applied is connected to the transfer electrode P at the connection section 112e. 1
The auxiliary electrode 110c connected to the transfer electrode 12a and having the transfer voltage P3 applied thereto is connected to the transfer electrode 1
12c. The connection with the other transfer electrodes is the same as that of the auxiliary electrodes 110a and 110c shown in FIG.

Next, the auxiliary electrode section 120 includes an auxiliary electrode 120b to which the transfer voltage P2 is applied and an auxiliary electrode 120c to which the transfer voltage P3 is applied. The auxiliary electrode 120b to which the transfer voltage P2 is applied is connected to the connection section 122f. , The auxiliary electrode 120c to which the transfer voltage P3 is applied is connected to the transfer electrode 122c at the connection part 122g.

Further, the following set of auxiliary electrode units 130
Is composed of an auxiliary electrode 130a to which the transfer voltage P1 is applied and an auxiliary electrode 130c to which the transfer voltage P3 is applied, as in the case of the auxiliary electrode unit 110. Hereinafter, two types of auxiliary electrodes composed of such a pair of two auxiliary electrodes will be described. The wiring structure with the auxiliary electrodes is formed by the alternate repeating structure of the electrode portions.

In this case, of the three transfer electrodes for each row, one of the two transfer electrodes having no open gate is not connected to the auxiliary electrode, but the adjacent transfer electrodes are both connected to the auxiliary electrode. Thereby, the influence of the wiring resistance of polycrystalline silicon can be minimized, and a CCD with improved transfer speed and transfer efficiency can be obtained.

FIG. 9 shows an embodiment of an electrode structure of an FFT type CCD driven by four phases, in which two auxiliary electrodes are similarly set. In the present embodiment, each of the auxiliary electrode portions has a transfer electrode (for example, 111a) having an open gate to which the transfer voltage P1 is applied, and three other transfer electrodes (to which the transfer voltages P2, P3, and P4 are applied). For example, one of the electrodes 111b, 111c and 111d) is composed of two auxiliary electrodes for supplying a transfer voltage to two transfer electrodes. The structure of the transfer electrode, the period of the repetitive structure of the auxiliary electrode portion, and the like are the same as those shown in FIG.

That is, the auxiliary electrode unit 110 applies the transfer voltage P
1 and an auxiliary electrode 110b to which a transfer voltage P2 is applied.
Is composed of an auxiliary electrode 120a to which the transfer voltage P1 is applied and an auxiliary electrode 120c to which the transfer voltage P3 is applied.
0a and the auxiliary electrode 130d to which the transfer voltage P4 is applied, and applies and supplies a transfer voltage to each corresponding transfer electrode. Hereinafter, three types of auxiliary electrode portions each including a set of two such auxiliary electrodes will be described. By repeating the above structure, a wiring structure using the auxiliary electrode is formed.

The solid-state imaging device provided with the CCD having the transfer electrode and the auxiliary electrode according to the present invention is not limited to the above-described embodiment, but can employ various embodiments. For example, as for the shape of the auxiliary electrode, in each of the above-described embodiments, a diagonal structure that rises to the right as shown in FIG. 1 is used.
For example, various shapes such as a diagonal structure having a turn (V-shaped structure) can be used. FIG.
The wiring configuration of such auxiliary electrodes in a three-phase drive of a solid-state imaging device using a T-type CCD is shown. Auxiliary electrode parts 11 to 17
Are symmetrical in configuration, with the center position in the horizontal direction as a boundary, and the right side is diagonally right up and the left side is diagonally left up. Note that, also in the present embodiment, the area covered by the auxiliary electrode, which is an insensitive area for imaging, is set equal for each column and each row.

The material of the auxiliary electrode is, for example, other metals such as Cu, Ti, W, Mo, Ta, or Ti.
A metal silicide such as Si ₂ , WSi ₂ , MoSi ₂ , TaSi ₂ , and NbSi ₂ may be used.

In the above, the electrode structure in the light receiving section of the FFT type CCD has been described. However, such an electrode structure can be applied to the light receiving section of the FT type CCD in the same manner.

[0075]

As described in detail above, the solid-state imaging device according to the present invention has the following effects. That is,
In the light receiving section of the FFT type CCD or FT type CCD,
A different configuration and shape from the transfer electrode, such as a metal or metal silicide auxiliary electrode, which is arranged diagonally to the transfer electrode, in addition to the transfer electrode made of polycrystalline silicon, which has a higher wiring resistance than metal In this way, the area covered by the auxiliary electrode, which does not transmit light, in the light receiving section is minimized, and efficient light reception / imaging and high transfer voltage to the transfer electrode are provided. A solid-state imaging device that achieves both high-speed and high-efficiency charge transfer can be realized.

At this time, by providing an open gate with the transfer electrode as an opening in a region where the auxiliary electrode does not exist, a solid-state imaging device with improved sensitivity to ultraviolet light can be obtained.

In particular, in such a solid-state imaging device,
By configuring the auxiliary electrode and the area of the open gate to be equal for each column and each row of the light receiving section, when imaging using the TDI driving method is performed, each area of the optical image to be imaged is positioned. It is possible to perform imaging such that the imaging sensitivity becomes uniform for each corresponding charge packet. Such an imaging method is required for applications such as a wafer inspection apparatus and a photomask inspection apparatus for inspecting an object moving at a constant speed on a belt conveyor. Especially in these inspection devices, the wavelength is 400 nm.
The following sensitivity to ultraviolet light may be required. However, by using the solid-state imaging device according to the present invention, a TDI having high sensitivity to ultraviolet light and capable of high-speed operation is provided.
A driving CCD is realized.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of a solid-state imaging device using an FFT-type CCD according to the present invention in three-phase driving.

FIG. 2 is an enlarged configuration diagram of a light receiving unit surface of the solid-state imaging device illustrated in FIG. 1;

FIG. 3 is a sectional view of the solid-state imaging device shown in FIG.

FIG. 4 is an enlarged configuration diagram of a light-receiving unit surface showing an embodiment of a solid-state imaging device using an FFT-type CCD according to the present invention in four-phase driving.

5 is a cross-sectional view of the solid-state imaging device shown in FIG. 4 taken along the line II-II.

FIG. 6 is an enlarged configuration diagram of a light-receiving unit surface showing an embodiment of a solid-state imaging device using an FFT-type CCD according to the present invention in two-phase driving.

7 is a cross-sectional view of the solid-state imaging device shown in FIG. 6, taken along the line III-III.

FIG. 8 is an enlarged configuration diagram of a light-receiving unit surface showing another embodiment of a solid-state imaging device using an FFT-type CCD according to the present invention in three-phase driving.

FIG. 9 is an enlarged configuration diagram of a light receiving unit surface showing another embodiment of a four-phase drive of a solid-state imaging device using an FFT-type CCD according to the present invention.

FIG. 10 is a configuration diagram illustrating another embodiment of a solid-state imaging device using an FFT-type CCD according to the present invention in three-phase driving.

FIG. 11 is a schematic configuration diagram of an FFT type CCD.

FIG. 12 is a schematic configuration diagram of an FT type CCD.

FIG. 13 is an equivalent circuit diagram of wiring of a conventional vertical shift register.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Light receiving part, 1a ... Unit pixel, 1b ... Isolation area, 2 ... Storage part, 3 ... Output part, 3a ... Horizontal shift register, 3b ... Amplifier part, 4 ... Charge transfer control part, 11-1
9 ... Auxiliary electrode part, 20 ... Semiconductor substrate, 21 ... Oxide film, 2
2 ... p layer, 23 ... n layer, 23a ... n ^- layer, 23b ... n
Layer, 24: diffusion layer, 25: insulating film, 110, 120, 1
30 ... Auxiliary electrode part, 110a-d, 120a-d, 13
0a to d: auxiliary electrodes, 111a to 111d, 112a to
112d, 113a to 113d, 114a to 114d,
115a to 115d: transfer electrodes, 112e to 112h,
113e to 113h, 114e to 114h ... connection part.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Akinaga Yamamoto, 1126 Nomachi, Hamamatsu-shi, Shizuoka Prefecture F-term in Hamamatsu Photonics Co., Ltd. FA50 5C024 AA01 AA20 CA16 GA11 GA15 GA40 GA49

Claims (8)

[Claims] 1. A matrix-shaped pixel structure formed on a substrate including a p-type semiconductor layer and an n-type semiconductor layer, the matrix including a plurality of columns dividing the horizontal direction and a plurality of rows dividing the vertical direction. The incident light image of the imaging object
A light receiving unit to be imaged; and a front side of the light receiving unit, the horizontal direction being parallel to the longitudinal direction of each row of the light receiving unit is set as a longitudinal direction, and a transfer voltage is applied to the light receiving unit. And a plurality of transfer electrodes for performing charge transfer in
A solid-state imaging device configured using one of a frame transfer type and a frame transfer type CCD, wherein each of the plurality of transfer electrodes is provided above the plurality of transfer electrodes, and the transfer voltage is applied thereto. And a plurality of auxiliary electrodes made of a metal or a metal silicide, each of which is connected to a corresponding one of the transfer electrodes provided in at least two rows of the light receiving unit and auxiliaryly applies and supplies the transfer voltage. A solid-state imaging device characterized by the above-mentioned. 2. The solid-state imaging device according to claim 1, wherein the plurality of auxiliary electrodes are provided with a direction oblique to the plurality of transfer electrodes as a longitudinal direction. 3. The CCD of one of the full frame transfer type and the frame transfer type is configured such that charge transfer is performed by the N-phase transfer voltage, and the plurality of auxiliary electrodes are N or less. 3. The solid-state imaging device according to claim 1, wherein an auxiliary electrode unit is configured by assembling a plurality of the auxiliary electrodes, and a plurality of the auxiliary electrode units are provided. 4. 4. The solid-state imaging device according to claim 3, wherein the auxiliary electrode unit is configured as a set of N auxiliary electrodes to which the transfer voltages of the N phases are respectively applied. 5. The semiconductor device according to claim 1, wherein an area covered by the plurality of auxiliary electrodes is equal to each column of the light receiving unit, and an area covered by the plurality of auxiliary electrodes is equal to each row of the light receiving unit. The solid-state imaging device according to claim 1, wherein: 6. Each of the rows of the light receiving sections has an open gate that is an opening in one of the transfer electrodes in a region between the adjacent auxiliary electrodes passing therethrough, and the open gate The solid-state imaging device according to any one of claims 1 to 5, wherein a diffusion layer made of a p-type semiconductor is provided in a surface-side region in the n-type semiconductor layer of the substrate corresponding to (i). 7. The light receiving unit according to claim 6, wherein the area of the open gate is equal to each column of the light receiving unit, and the area of the open gate is equal to each row of the light receiving unit. The solid-state imaging device according to claim 1. 8. The method according to claim 8, wherein the transfer voltages applied to the plurality of transfer electrodes and the plurality of auxiliary electrodes are transferred at a speed corresponding to a moving speed of the imaging target, and the transfer voltage is applied to the optical image of the imaging target. TDI for receiving and imaging without blur
The solid-state imaging device according to any one of claims 1 to 7, further comprising a charge transfer control unit controlled by a driving method.