JPH0794695A - Structure of linear sensor chip - Google Patents

Abstract

PURPOSE:To provide a structure of linear sensor chip in which the adverse effect of the wiring resistance on the output characteristics of linear sensor is suppressed and the fabrication cost is reduced by decreasing the chip area. CONSTITUTION:A linear sensor chip 10 comprises a light receiving part 12 disposed on a semiconductor substrate 11, a transfer gate 14, a CCD shift register 16, and a drive circuit 20 wherein pads 22 for providing the power supply terminal parts and the ground terminal parts are juxtaposed on the semiconductor substrate 11 in the vicinity of the drive circuit 20. Since conventional power supply wiring and ground wiring are not required, fluctuation of output characteristics due to increase of wiring resistance is suppressed. The chip area can also be decreased correspondingly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor type image sensor (imaging device), and more particularly to a chip structure which constitutes a linear sensor which uses the brightness of only one horizontal line as an electric signal.

[0002]

2. Description of the Related Art Generally, for reading stripe patterns such as facsimiles and bar codes, or for industrial control and measurement,
A semiconductor linear sensor is used. This linear sensor is usually provided with a light receiving section made up of a large number of photodiodes arranged in a row in a row on a chip made of a semiconductor single crystal substrate. Outputs are picked up one after another by a CCD shift register via a transfer gate (accumulation unit + shift gate), and a horizontal one-line bright and dark striped pattern is converted into an electric signal and output to the outside. .

In this CCD shift register, for example, a P-type silicon single crystal substrate is coated with a silicon oxide film, and a large number of electrodes made of an aluminum vapor-deposited film are further arranged thereon. Alternatively, a drive circuit provided on the package side continuously applies a pulse voltage to each electrode to form a depletion layer in the single-crystal substrate one after another, and the charge from the photodiode is sequentially shifted in the longitudinal direction. You can do it.

[0004]

By the way, among the linear sensors, the type in which the drive circuit of the CCD shift register is built in the chip is, as shown in FIG. 4, a CCD shift register on the surface of the chip 40. A power supply wiring 44 to the drive circuit 42 and a ground (ground) wiring 46 are laid along the longitudinal direction of the chip. The power supply to the drive circuit 42 is an external power supply (not shown) at one end of these wirings 44 and 46. And each wiring 44, 46 and each drive circuit 42
This is done by connecting and respectively.

However, when such a power supply wiring 44 and a ground wiring 46 are integrally provided on the chip 40, the wirings 44 and 46 are usually formed by vapor-depositing aluminum on the chip 40. If the dimension of the chip in the longitudinal direction is large, the wirings 44 and 46 are
There is a possibility that the resistance value of itself becomes large, a difference occurs in the voltage value applied to each drive circuit, the pulse voltage value applied to each electrode of the CCD shift register 48 differs, and the output characteristics thereof are adversely affected.

In addition, in the case where the power supply wiring 44 and the ground wiring 46 are juxtaposed on both sides of the chip 40 in this way, the width of the aluminum vapor deposition film for one wiring is 10 each.
Since it exceeds 0 μm, there is a problem that the width dimension of the chip 40 increases correspondingly, the slice area of the silicon single crystal substrate at the time of chip manufacturing increases, and the manufacturing cost increases.

In view of the above problems, the present invention provides a linear sensor chip structure capable of reducing the influence of the wiring resistance of the linear sensor on the output characteristics and reducing the chip area to reduce the manufacturing cost. With the goal.

[0008]

In order to achieve the above object, according to the present invention, a light receiving portion composed of a large number of photodiodes juxtaposed in one horizontal row and the respective electrical outputs from the photodiodes are sequentially arranged. It is sandwiched between the CCD shift register that picks up the signals individually and converts them into a series of electric signals, and the light receiving section and the CCD shift register, and the electrical output from the light receiving section is CC.
The transfer gate that transmits to the D shift register,
In a linear sensor formed on a semiconductor substrate, a drive circuit for sequentially applying a pulse voltage to each electrode of the CCD shift register is provided beside the CCD shift register on the semiconductor substrate, and the semiconductor substrate near the drive circuit is further provided. A linear sensor chip structure is provided, in which pads that form a power supply terminal portion and a ground terminal portion of a drive circuit are arranged side by side.

In a preferred embodiment, the pads are arranged in a line along the chip longitudinal direction.

In a further preferred embodiment, a linear sensor having the chip structure according to the present invention or the embodiment described above and further having a package accommodating the chip structure is realized.

In a linear sensor according to another preferred embodiment, the pad is electrically connected to the wiring on the package side by wire bonding.

[0012]

Since the pads forming the power supply terminal portion and the ground terminal portion to the drive circuit are arranged in the vicinity of the CCD shift register drive circuit on the chip, the power supply terminal formed on the package side is described above. Electrical connection can be made by wire bonding with the pad. Further, by installing these pads, it is not necessary to secure a power supply wiring / ground wiring area on the chip, and the chip area can be reduced.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a chip that constitutes the linear sensor of the present invention. Linear sensor chip 1
Reference numeral 0 denotes a light receiving portion 1 including a large number of mini PN photodiodes arranged in a row in the center of the semiconductor single crystal substrate 11.
Equipped with 2. This PN photodiode is configured as a kind of diode that generates a current in response to light.

Transfer gates 14 for carrying the electric charges generated in the light receiving portion 12 are provided on both sides of the light receiving portion 12 in the width direction, and the electric charges from the transfer gate 14 are sequentially picked up outside thereof. A CCD shift register 16 for converting a series of electric signals is provided.
The CCD shift register 16 is a semiconductor single crystal substrate 1
The surface of 1 is covered with an insulating film, and a large number of electrodes made of, for example, an aluminum vapor-deposited film are arranged on the surface of the insulating film. An output circuit 18 for outputting a continuous electric signal to the outside is provided.

On the side of the CCD shift register 16, a pulse voltage is sequentially applied to each electrode of the register 16,
A drive circuit 20 for forming a depletion layer for charging charges is provided in the substrate portion below the electrode. This drive circuit 20
Numeral 8 is configured as a kind of switching circuit which repeats connection ON / OFF of a pulse voltage from the outside with respect to one electrode, and shifts the charges from the transfer gate 14 to the output circuit 18 in order.

In the linear sensor chip 10 constructed as described above, according to the present embodiment, each drive circuit 20 is provided.
On the single crystal substrate 11 in the vicinity of the bonding pad 22 serving as a power supply terminal and a ground terminal of the drive circuit 20.
Are provided in a row along the chip longitudinal direction (direction of arrow A). This is formed for the purpose of eliminating the power supply wiring and the ground wiring from the chip 10 to the drive circuit 20, reducing the width dimension W of the chip as much as possible, and reducing the area of the entire chip.

Thus, these bonding pads 22 arranged in a row in the lateral side of the chip side are provided on the thick film wiring portion 26 on the package 24 side, as shown in FIG. 2, when the chip 10 is incorporated in the package. On the other hand, they are electrically connected by wire bonding such as Au wire 28. FIG. 3 is a partial external view of the semiconductor package 24 in which each of the bonding pads 22 is connected to each thick film wiring portion 26 independent of each other. In connection with this package side, in addition to the connection form shown in FIG. 3, each thick film wiring section on the package side, which is the power supply side and the ground side, is put together into You may make it wire-bond.

As described above, according to this embodiment, the two bonding pads 2 serving as the power supply terminal and the ground terminal for each drive circuit 20 are provided on the chip 10 of the linear sensor.
2 is provided and is connected to the wiring portion on the package side by wire bonding, so that power can be supplied to each drive circuit 20 with a resistance lower by the amount corresponding to the elimination of the conventional power / ground wiring on the chip. in addition,
Since it is not necessary to secure a power supply / ground wiring region in the chip, the area of the chip itself can be reduced, and the manufacturing cost can be reduced along with the reduction of the slice area of the single crystal plate at the time of manufacturing.

Although the CCD shift registers 16 are provided on both sides of the light receiving portion 12 in the illustrated embodiment,
The chip structure of the present invention can be similarly applied to a linear sensor in which a CCD shift register is arranged on only one side.

[0020]

As described above, according to the present invention,
Since the pads forming the power supply terminal and the ground terminal to the drive circuit are arranged in parallel near the CCD shift register drive circuit on the chip, even if the chip itself is long, stable power supply to the drive circuit and stable output are possible. A characteristic linear sensor can be provided.

In addition, by installing these pads, it is not necessary to secure a power wiring / ground wiring area on the chip, the chip area can be reduced, and the manufacturing cost can be greatly reduced.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a chip structure according to the present invention.

FIG. 2 is a cross-sectional view in which the chip of FIG. 1 is mounted on the package side.

3 is a partial external perspective view of FIG. 2. FIG.

FIG. 4 is a configuration diagram of a conventional chip structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Chip 11 ... Semiconductor substrate 12 ... Light receiving part (photodiode) 14 ... Transfer gate 16 ... CCD shift register 20 ... Drive circuit 22 ... Pad 24 ... Package

Claims (4)

[Claims] 1. A light-receiving unit composed of a large number of photodiodes arranged in a row in a row, a CCD shift register for picking up the electrical outputs from the photodiodes in order and converting them into a series of electrical signals, In a linear sensor in which a transfer gate, which is sandwiched between a light receiving portion and a CCD shift register and which transmits an electric output from the light receiving portion to the CCD shift register, is formed on a semiconductor substrate, in a lateral direction of the CCD shift register on the semiconductor substrate. , CC
A drive circuit for sequentially applying a pulse voltage to each electrode of the D shift register is provided, and pads for the power supply terminal portion and the ground terminal portion of the drive circuit are arranged side by side on a semiconductor substrate near the drive circuit. And the linear sensor chip structure. 2. The chip structure of the linear sensor according to claim 1, wherein the pads are arranged in a row along the longitudinal direction of the chip. 3. A linear sensor having the chip structure according to claim 1 or 2, further comprising a package for housing the chip structure. 4. The linear sensor according to claim 3, wherein the pad is electrically connected to the wiring on the package side by wire bonding.