JP2867780B2 - Back-illuminated infrared solid-state imaging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a back-illuminated infrared solid-state imaging device for converting infrared image information into a time-series electric signal.

[0002]

2. Description of the Related Art FIG. 2 shows a planar structure in the vicinity of an output portion of a conventional back-illuminated infrared solid-state imaging device. This is a two-dimensional element. The back-illuminated infrared detecting elements 1 are two-dimensionally arranged, and a vertical charge-coupled element 2 for transferring charges from each detecting element 1 runs vertically between the detecting elements. The end of the vertical charge coupled device column is connected to the horizontal charge coupled device 3. At the output end of the horizontal charge-coupled device 3, there is a floating diffusion capacitance 5 via a read gate 4, which is further connected to a reset transistor 6 which sweeps out signal charges and resets them. A two-stage source follower amplifier (on-chip amplifier) 18 is connected to the floating diffusion capacitance 5. In this example, there are two stages,
The on-chip amplifier may have a multistage configuration of more than this. In the conventional example, all stages of the on-chip amplifier are provided near the output terminal of the horizontal charge-coupled device.

[0003]

FIG. 3 shows a structure in which a back-illuminated infrared solid-state imaging device chip is mounted on a package and a cooling device. As shown in FIG. 3, the chip 11 is a package 19 having an open window through which infrared light having infrared image information is incident.
And the front side is sealed with a package lid 21.
The back-illuminated infrared solid-state imaging device generally requires cooling. This cooling is performed by bringing the lid 21 into close contact with the cold stage 22 of the cooling device. Therefore, the heat of the back-illuminated infrared solid-state imaging device chip 11 is released from the contact surface with the package 19 through the package 19 and the lid 21. The on-chip amplifier occupies most of the power consumption of the back-illuminated infrared solid-state imaging device and acts as a heat source. In the conventional on-chip amplifier, since all stages are provided close to the output terminal of the horizontal charge-coupled device, the on-chip amplifier is located near the center of the chip, just off the contact surface with the package (the back surface package mounting area 12 in FIG. 2). doing.
Therefore, the heat generated by the on-chip amplifier is difficult to escape to the package, and the heat is supplied near the imaging region, so that the temperature at which the imaging region reaches the cooling temperature is increased.

[0004]

According to the present invention, a light receiving portion comprising a back-side illuminated infrared detecting element is arranged one-dimensionally or two-dimensionally, optical signal charges are transferred from these light receiving portions by a charge-coupled device, and an output portion is provided. A back-illuminated infrared solid-state imaging device that includes at least two or more stages of amplifier circuits and outputs infrared image information as a time-series electric signal from the on-chip amplifier, wherein the second and subsequent stages of the on-chip amplifier are :
Areas that suffer performance degradation during the mounting process of the infrared solid-state imaging device
Near the edge of the chip outside the
Is located just above the contact surface .

[0005]

Generally, in a multi-stage amplifier circuit, power consumption increases from the first stage to the subsequent stage. In the back-illuminated infrared solid-state imaging device of the present invention, since the second and subsequent stages of the on-chip amplifier are located near the chip end outside the area where performance is deteriorated in the mounting process of the infrared solid-state imaging device, the charge-coupled device The power consumption near the output end is greatly reduced, and the amount of heat generated there is small. In addition, since the vicinity of the chip end is far from the imaging area and directly above the contact surface with the package, heat generated in the second and subsequent stages of the on-chip amplifier is less likely to be transmitted to the imaging area and easily escapes to the package. For these reasons, in the present invention, the temperature at which the imaging region reaches the cooling end can be lowered.

[0006]

Next, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a planar structure in the vicinity of an output unit according to an embodiment of the present invention. This is a two-dimensional element, and the on-chip amplifier is a two-stage source follower. In this example, there are two stages, but the on-chip amplifier may have a multistage configuration of more stages. The back-illuminated infrared detecting elements 1 are two-dimensionally arranged, and a vertical charge-coupled element 2 for transferring charges from each detecting element 1 runs vertically between the detecting elements. The end of the vertical charge coupled device row is connected to the horizontal charge coupled device 3. A floating diffusion capacitor 5 is provided at the end of the horizontal charge-coupled device 3 via a read gate 4 and is connected to the gate 14 of the first-stage drive transistor of the two-stage source follower amplifier.
The output of the first stage 7 of the two-stage source follower amplifier is drawn from the drain 15 of the source / load transistor of the drive transistor, and the metal signal line 9 is connected to the gate 14 of the drive transistor of the second stage 8 of the two-stage source follower amplifier .
Connected by The final two-stage source follower amplifier output is drawn from the drain 15 of the source / load transistor of the second-stage drive transistor. The first stage 7 of the two-stage source follower amplifier is located near the output end of the horizontal charge-coupled device, while the second stage 8 of the two-stage source follower amplifier is located in the back surface package mounting area 12 near the bonding pad 10 for the amplifier output. It is provided in. The position where the second-stage source follower amplifier 2nd stage 8 is located is not affected by breakage or the like due to chip cutting work or the like. 2
Comparing the first stage and the second stage of the two-stage source follower amplifier, the channel width of the second stage is several times larger than that of the second stage, and the power consumption increases accordingly. Since the second stage of the amplifier is located immediately above the contact surface with the package away from the imaging region, cooling can be performed efficiently.

[0008]

As described above, in the back-illuminated infrared solid-state imaging device of the present invention, the second and subsequent stages of the on-chip amplifier, which generate a large amount of heat, are located immediately above the package contact surface with good cooling efficiency. There is an effect that the temperature at which cooling of the imaging region can be reduced can be reduced.

[Brief description of the drawings]

FIG. 1 is a plan view of the vicinity of an output unit in a back-illuminated infrared solid-state imaging device of the present invention.

FIG. 2 is a plan view showing a structure near an output unit in a conventional back-illuminated infrared solid-state imaging device.

FIG. 3 is a diagram showing a state in which a back-illuminated infrared solid-state imaging device chip is mounted on a package and a cooling device;
(A) is a view of the package on which the chip is mounted viewed from the back,
(B) is a longitudinal cross-sectional structure diagram of the cooling device mounted state.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 back-illuminated infrared detection element 2 vertical charge-coupled element 3 horizontal charge-coupled element 4 read gate 5 floating diffusion capacitance 6 reset transistor 7 two-stage source follower amplifier first stage 8 two-stage source follower amplifier second stage 9 metal signal Line 10 Bonding pad 11 Backside illuminated infrared solid-state imaging device chip 12 Backside package mounting area 13 Drain of drive transistor 14 Gate of drive transistor 15 Source of load transistor and drain of load transistor 16 Load transistor gate 17 Load transistor source 18 2 Step source follower amplifier 19 Package with back entrance window 20 Lead 21 Package lid 22 Cold stage of cooling device

Claims (1)

(57) [Claims] 1. A light receiving section comprising a back-illuminated infrared detecting element is arranged one-dimensionally or two-dimensionally, optical signal charges are transferred from these light receiving parts by a charge-coupled device, and at least two or more stages of amplifier circuits are output to an output part. A back-illuminated infrared solid-state imaging device that outputs infrared image information as a time-series electrical signal from the on-chip amplifier , wherein the second and subsequent stages of the on-chip amplifier are mounted with the infrared solid-state imaging device.
In the vicinity of the chip edge outside the area where performance degradation occurs during the process
A back-illuminated infrared solid-state imaging device, which is located immediately above a contact surface with a cooled package .