JPS6161588B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solid-state imaging device having a structure in which a charge-coupled imaging device and its driving circuit are provided on the same semiconductor substrate.

Recently, charge-coupled devices (hereinafter referred to as charge-coupled devices) have been used as image sensors for facsimile and television cameras.
A solid-state imaging device using a CCD (CCD) is used.

Conventionally, a solid-state imaging device using a CCD as an imaging element has a structure in which the CCD and its driving circuit are provided on the same semiconductor substrate. The load capacitance of a CCD as seen from the drive circuit is several hundred pF.
When a CCD and a drive circuit are formed on the same semiconductor substrate, the drive circuit becomes a heat source, and depending on where the drive circuit is installed, the temperature distribution on the semiconductor substrate may become uneven. It was hot.

FIG. 1 is a plan view of an example of a semiconductor substrate portion of a conventional solid-state imaging device.

In FIG. 1, 1 is a semiconductor substrate, 2 is a charge-coupled image pickup device, 3 is a pulse generation section of a drive circuit, and 4 is a driver section of the drive circuit. The dash-dotted line indicates isotherm line 5. With this arrangement, isotherm 5
As shown in , the temperature near the rear stage section 4 of the drive circuit increases, and the temperature decreases as the distance from the rear stage section 4 increases, and the temperature distribution in the charge-coupled image sensor section 2 becomes non-uniform.

The charge-coupled image sensor 2 has the drawback that as the temperature rises, thermally generated charges, ie, dark current, increase, the S/N ratio decreases, and the output of the solid-state image sensor becomes non-uniform.

The present invention eliminates the above-mentioned drawbacks and provides a solid-state imaging device in which the temperature distribution of the charge-coupled imaging device is made uniform and the S/N ratio and output uniformity are improved by distributing the rear part of the drive circuit. It is something to do.

A solid-state imaging device of the present invention includes a semiconductor substrate on which a charge-coupled imaging device and a drive circuit including a pulse generation section and a driver section are formed, wherein a plurality of semiconductor substrates forming a driver section of the drive circuit are provided. Circuit elements having the same configuration are distributed around the charge-coupled image sensor so that the temperature distribution of the charge-coupled image sensor due to heat generated by these circuit elements is uniform.

The present invention will be explained by examples. FIG. 2 is a plan view of an embodiment of the present invention, FIG. 3 is a circuit diagram of the drive circuit of the embodiment shown in FIG. 2, and FIG. 4 is a waveform diagram for explaining the operation of the drive circuit. .

As shown in FIG. 2, the circuit elements constituting the driver section 4 of the drive circuit are distributed at ten locations.
4-1 to 4-10 indicate dispersion positions. That is,
They are distributed around the charge coupled device 2.

The circuit elements constituting the driver section 4 of the drive circuit are located in an area 4-1 surrounded by a dashed line in FIG.
~ Divide as shown in 4-10. The drive circuit is provided on a P-type semiconductor substrate and an N-type semiconductor substrate.
Assume that MOS transistors are used. The pulse generating section 3 of the drive circuit includes two stages of E/D type inverters (Q1, Q2) and (Q3, Q4) using depletion type transistors Q1 and Q3, and a bootstrap type inverter 2 using capacitors C1 and C2. Stages (C1, Q5, Q6, Q7), (C2,
It is formed by a total of four stages of serial inverter circuits including Q8, Q9, Q10), and generates the clocks φ1 and φ2 necessary for the driver section 4. On the other hand, in the driver section 4, the same circuit element consisting of two MOS transistors Q11 and Q12 connected in series is connected to distributed positions 4-1 to 4-5.
are connected in parallel, and at distributed positions 4-6~
4-10 are connected in parallel. MOS transistor Q of each circuit element distributed in this way
11 is supplied with the clock φ1 generated by the pulse generator 3, and the base of the MOS transistor Q12 of each circuit element is supplied with the clock φ2 generated by the pulse generator 3.

Next, the operations of the pulse generating section 3 and the driver section 4 will be explained with reference to the waveform diagram of FIG. 4. The pulse generator 3 generates clocks φ1 and φ2 whose phases are inverted from each other based on the input φin. now,
At time _t1 , clock φ1 is at high level and clock φ2 is at low level, so clock φ1
The MOS transistor Q11 of each circuit element whose gate is supplied with the clock φ2 is turned on, and the MOS transistor Q1 of each circuit element whose gate is supplied with the clock φ2 is turned on.
2 is off, so the output φ of the driver section 4
out becomes high level (power supply voltage V _DD ). Conversely, at time _t2 , clock φ1 is at low level and clock φ2 is at high level, so clock φ1 is applied to each circuit element to which the gate is supplied.
MOS transistor Q11 is turned off and clock φ
Since the MOS transistor Q12 of each circuit element to which 2 is supplied to the gate is turned on, the output φout of the driver section 4 becomes a low level (ground potential). In this way, the driver section 4 uses the push-pull operation to control the MOS transistor Q1 of each circuit element.
Both Q1 and Q12 are not turned on at the same time, resulting in a circuit configuration that suppresses power consumption.

The above drive circuit is an example.
The transistors used are not limited to N-type MOS transistors, but may also be P-type MOS transistors. In addition, CMOS using both
Of course, it is also possible to configure

When the circuit elements constituting the tribar section of the drive circuit are distributed and arranged as described above, the isothermal line 5 is shown in Fig. 2.
As shown, the temperature distribution of the charge-coupled image sensor 2 becomes uniform, and the S/N ratio and output uniformity improve.

As explained in detail above, according to the present invention,
The effect is significant because a solid-state imaging device with improved S/N ratio and output uniformity can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an example of a semiconductor substrate portion of a conventional solid-state imaging device, FIG. 2 is a plan view of an embodiment of the present invention, and FIG. 3 is a drawing of a drive circuit of the embodiment shown in FIG. 4 are waveform diagrams for explaining the operation of the drive circuit shown in FIG. 3. 1... Semiconductor substrate, 2... Charge-coupled image sensor,
3... Pulse generating section of the drive circuit, 4... Driver section of the drive circuit, 5... Isothermal line.

Claims (1)

[Claims] 1. In a solid-state imaging device including a semiconductor substrate on which a charge-coupled image sensor and a drive circuit including a pulse generation section and a driver section are formed, a plurality of circuit elements having the same configuration constituting the driver section of the drive circuit, A solid-state imaging device characterized in that the solid-state imaging device is distributed around the charge-coupled image sensor so that the temperature distribution of the charge-coupled image sensor due to heat generated by these circuit elements is uniform.