JPH06120381A - Solid image pickup device - Google Patents

Abstract

PURPOSE:To improve temperature control performance during cooling by placing a thermal cushioning member of a sandwich construction made of a member having a high heat conductivity sandwiched between members having a low heat conductivity between a solid image pickup element and an electronic cooling element. CONSTITUTION:An electric current is applied to a Peltier element 40 for quickly cooling a CCD2O. A polyimide layer 31 with a low heat conductivity bonded to the rear surface of the Peltier element 30 is gradually cooled off. An aluminum layer 32 bonded to the rear surface of the polyimide layer 31 is also cooled off. The aluminum layer 32 is a member with a high heat conductivity and a member of polyimide layer 33 underneath said layer 32 has a low heat conductivity; therefore, even if the cooling of the polyimide 31 is not performed uniformly because of irregularity in the temperature cooling at the Peltier element 40, the temperature cooling can be uniformed by the aluminum layer 32. Thereafter, the polyimide layer 33 is gradually cooled off, and the CCD20 bonded to the rear surface of the polyimide layer 33 is slowly cooled off. Therefore, the CCD20 can be cooled off without giving great damages and also without degrading the characteristics.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state image pickup device provided with an electronic cooling type element for cooling the solid-state image pickup element.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 60-220965 discloses
A solid-state imaging device having an electronically cooled element such as a Peltier element is described. In this conventional example, the light receiving part of the solid-state imaging device is arranged on the electronic cooling type device to cool the light receiving part, so that the dark current generated when the charge generated in the light receiving part of the solid-state imaging device is transferred. It is intended to reduce.

[0003]

By the way, when the solid-state image pickup device is cooled by the electronic cooling type device, there is a possibility that the solid-state image pickup device may be broken or the characteristics may be deteriorated by the rapid cooling. Therefore, the conventional solid-state image pickup device is provided with a controller for controlling the temperature change of the electronic cooling type element to prevent destruction of the solid-state image pickup element and deterioration of characteristics due to rapid cooling.

However, even if the temperature change of the electronic cooling type element is controlled by using the controller, it is difficult to make a fine adjustment to uniformly cool the solid-state image pickup element. For this reason, the partial rapid cooling caused by the inability to uniformly cool the solid-state image sensor causes the destruction and deterioration of the characteristics.

Also, even if a controller is provided, the device itself has no protection against quenching. Therefore, when the controller malfunctions and the temperature of the electronic cooling type element changes abruptly, the solid-state image pickup element is broken or the characteristics are deteriorated.

It is an object of the present invention to solve the above problems and provide a solid-state image pickup device having excellent temperature control performance during cooling.

[0007]

In order to solve the above-mentioned problems, the solid-state image pickup device of the present invention has a thermal buffer member interposed between a solid-state image pickup element and an electronic cooling element for cooling the solid-state image pickup element. There is. As the heat buffer member, a member having a structure in which a material having a high thermal conductivity is sandwiched between materials having a lower thermal conductivity than this material is used.

[0008]

According to the solid-state image pickup device of the present invention, a heat-absorbing member having a sandwich structure in which a material having a high thermal conductivity is sandwiched between the solid-state image pickup element and the electronic cooling element by a material having a lower thermal conductivity than this material. Is intervening. The material having a low thermal conductivity of the heat buffering member reduces the cooling rate of the solid-state imaging device, and the material having a high thermal conductivity of the heat buffering member uniformizes the cooling of the solid-state imaging device. In particular, since the material with high thermal conductivity is sandwiched by the materials with low thermal conductivity, the decrease in temperature conducted from one material with low thermal conductivity is conducted to the material with low thermal conductivity. Before it is fully conducted in a material with high thermal conductivity. Therefore, uniformization of temperature decrease is promoted.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the solid-state image pickup device of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a perspective view showing the structure of this embodiment, and FIG. 2 is a sectional view showing the structure of this embodiment. As shown in the perspective view of FIG. 1, the solid-state imaging device is a ceramic substrate 10 using Al ₂ O ₃ having a stepped recess 11, and a solid-state imaging device fixed in the recess 11 of the ceramic substrate 10. CCD 20 made of silicon
And the CCD provided on the concave portion 11 of the ceramic substrate 10.
A heat buffering member 30 surrounding 20 and a Peltier element 4 which is an electronic cooling type element bonded to the upper surface of the heat buffering member 30.
It has 0.

As can be seen from the sectional view of FIG. 2, an opening 12 is formed in the bottom surface of the recess 11 of the ceramic substrate 10, and the light passing through the opening 12 is applied to the back surface of the CCD 20. The back surface of the CCD 20 is thinly shaved to improve the light receiving sensitivity. As a result, the thickness of the uncut portion is about 500 μm, while the thickness of the cut portion is 10 to 20 μm.

The heat buffer member 30 has a three-layer sandwich structure, and an Al layer 32 having a thickness of about 500 μm is provided between a polyimide layer 31 having a thickness of 100 to 200 μm and a polyimide layer 33 having a thickness of 500 to 800 μm. It is sandwiched. The back surface of the polyimide layer 33 is bonded to the CCD 20,
The joint area is about 1.2 cm × 1.2 cm.

When a current is applied to the Peltier element 40 to cool the CCD 20, the Peltier element 40 is rapidly cooled to about -40 ° C. A polyimide layer 3 is formed on the back surface of the Peltier element 40.
1, the polyimide layer 31 is cooled. Since the polyimide layer 31 is a material having a low thermal conductivity, cooling is gradually performed.

An Al layer 32 is bonded to the back surface of the polyimide layer 31, and the Al layer 32 is also cooled according to the cooling of the polyimide layer 31. Since the Al layer 32 is a material having a high thermal conductivity, the temperature of the entire Al layer 32 is uniform. That is, even when the temperature of the Peltier element 40 is unevenly cooled and the polyimide layer 31 is not uniformly cooled, the Al layer 32 uniformly cools the temperature. This is because the polyimide layer 33 below the Al layer 32 is a material with low thermal conductivity,
This is because before the polyimide layer 33 is cooled by the Al layer 32, cold air is sufficiently circulated in the Al layer 32 to be cooled uniformly. In addition, since the Al layer 32 is sandwiched between the polyimide layers 31 and 33 having low thermal conductivity, the Al layer 32 is in the same state as the heat retaining bottle, and the circulation of cold air is further accelerated, so that the Al layer 3
The homogenization of the temperature of 2 is promoted.

After the Al layer 32 is uniformly cooled in this manner, the polyimide layer 33 is gradually cooled. The CCD 20 is bonded to the back surface of the polyimide layer 33, and the CCD 20 is cooled according to the cooling of the polyimide layer 33. Since the polyimide layer 33 is cooled slowly, the CCD 20 is also cooled slowly, for example, at 5 ° C./min or less. By cooling the CCD 20 slowly in this way, it is possible to cool the CCD 20 without causing significant damage and without deteriorating the characteristics.

The heat buffer member 30 which is a feature of this embodiment is
It has a sandwich structure in which the Al layer 32 is sandwiched between the polyimide layer 31 and the polyimide layer 33. The thermal conductivity of the Al layer 32 is as high as 2.38 [Wcm ^-1 deg ^-1 ], and the thermal conductivity of the polyimide layers 31, 33 is 0.0012 [Wcm ^-1 deg].
^-1 ] and low. Another material having a close thermal conductivity may be used for the thermal buffer member 30, and in this case, the cooling rate of the CCD 20 is 5 ° C./° C. by changing the layer thickness by the amount of the different thermal conductivity. It can be kept below min.

The present invention is not limited to the backside illumination type CCD, but may be a frontside illumination type CCD. Further, the present invention is applicable to any solid state detector, such as AP.
It is also applied to D (avalanche photo diode) and PD (photo diode).

[0017]

According to the solid-state image pickup device of the present invention, the cooling rate of the solid-state image pickup element is relaxed by the material having a low thermal conductivity of the thermal buffer member, and the solid-state image pickup element is made of the material having a high thermal conductivity of the thermal buffer member. Cooling is made uniform. Therefore, the deterioration of the characteristics during cooling and the destruction of the device can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a perspective view showing a structure of a solid-state imaging device.

FIG. 2 is a cross-sectional view showing the structure of a solid-state imaging device.

[Explanation of symbols]

10 ... Ceramic substrate, 20 ... CCD, 30 ... Thermal buffer member, 31, 33 ... Polyimide layer, 32 ... Al layer, 40 ...
Peltier element.

Claims (1)

[Claims] 1. A solid-state imaging device for cooling a solid-state imaging device with an electronic cooling type device, wherein a thermal buffer member is interposed between the electronic cooling type device and the solid-state imaging device, and the thermal buffer member conducts heat. A solid-state imaging device, which is a member having a structure in which a material having a high thermal conductivity is sandwiched between materials having a lower thermal conductivity than this material.