JPS63144564A - Semiconductor image sensing device - Google Patents

Abstract

PURPOSE:To prevent the incidence of stray light from the rear to a photoelectric conversion layer, and to obvaite a crosstalk in a semiconductor image sensing device by forming an optical absorption layer to the rear of the photoelectric conversion layer through a semi-insulating layer. CONSTITUTION:An optical absorption layer 2, a semi-insulating layer 3 and a photoelectric conversion layer 4 are grown onto a semi-insulating CdTe substrate 1 in an epitaxial manner. The semiconductor base body is mesa-etched to a striped shape at a period such as one of 50mum/50mum up to depth reaching the semi-insulating layer 3, thus shaping inter-element isolation regions 6. Counter electrodes 5 are formed onto the photoelectric conversion layer 4 at a distance of a value such as 50mum. Regions 4A in size such as 50mumX50mum exposed among the electrodes 5 in the photoelectric conversion layer 4 function as light- receiving regions in each photodetecting element.

Description

[Detailed Description of the Invention] (Summary) The present invention provides a semiconductor imaging device with a light absorption layer behind a photoelectric conversion layer via a semi-insulating layer to prevent stray light within the semiconductor substrate. This improves crosstalk.

[Industrial application field]

The present invention relates to a semiconductor imaging device, and more particularly to a structure for preventing stray light in a front-illuminated semiconductor imaging device.

If stray light generated inside the base of a semi-four-body imaging device enters the photoelectric conversion region of the photodetector element, it will affect the output signal and cause crosstalk between the elements, so it is important to prevent stray light. be.

[Problems to be solved by the prior art and the invention 1 A front-illuminated semiconductor imaging device usually has a plurality of photodetecting elements arranged in an array on a semiconductor substrate, and the light is received from each photodetecting element. Figure 3 shows a schematic diagram of one conventional example.The conventional example is a photoconductive infrared imaging device whose electrical resistance changes depending on the incident light. (CdTe) Mercury cadmium tellurium (Hg+-) epitaxially grown on the semiconductor substrate 11
xcdxTe) semi-quartet layer 14 is used as a photoelectric conversion layer, and two electrodes 15 are opposed on this layer 14 to constitute one photodetecting element.

These photodetecting elements are arranged in an array, and Hg is placed between each element.
An inter-element isolation region 16 is provided in which the t-xcdxTeJW 14 is removed by etching.

The light-receiving region of each of the above-mentioned photodetecting elements is the 'g+-xcdxTeJi region 14^ exposed between the opposing electrodes 15, and the resistance value changes depending on the amount of light incident from the surface of this light-receiving region 14A. Then, a predetermined voltage is applied between the electrodes 15 and detected.

However, as illustrated in FIG. 4, in the device isolation region 16 of this conventional example, the light that reaches the front surface directly enters the CdTe substrate 11, is transmitted without being absorbed, is reflected on the back surface, and at least One portion becomes stray light that reaches the light receiving area 14A where photoelectric conversion is performed.

Furthermore, a phenomenon that is noticeable when the imaged object includes a high-brightness area is that a portion of the light incident on a certain photodetecting element passes through without being absorbed by the photoelectric conversion [14], and this becomes stray light and is transmitted to other photodetectors. There is also the problem of reaching the light sensing element.

In a front-illuminated imaging device like this conventional example, it is originally desirable that only the light that directly enters the light-receiving area from the 12th surface is photoelectrically converted, and the above stray light causes crosstalk between the photodetecting elements. It is necessary to prevent this.

[Means for Solving the Problems] The above problems are solved by the semiconductor imaging device according to the present invention, in which a light absorption layer is provided behind the photoelectric conversion layer with a semi-insulating layer interposed therebetween.

[For production]

The semiconductor imaging device according to the present invention, as illustrated in FIG.
Behind the photoelectric conversion layer 4, that is, in the opposite direction to the light incident side,
A light absorption layer 2 separated from a photoelectric conversion layer 4 by a semi-insulating layer 3 is provided.

This light absorbing layer 2 absorbs stray light incident from outside the light receiving area 4A of the photodetecting element described above and stray light transmitted through the charge conversion layer 4 of the photodetecting element. Furthermore, if there is any stray light transmitted through this light absorption layer 2 and reflected on the back surface of the substrate 1, this is also absorbed, and stray light is prevented from entering the photoelectric conversion layer 4 from the rear.
Crosstalk within the semiconductor imaging device is prevented.

〔Example〕

The present invention will be specifically explained below with reference to an example schematically shown in FIG.

The semiconductor substrate of this example is a semi-insulating CdTe substrate formed by, for example, a CVD method. Board sales layer 2, semi-insulating N3
For example, the photoelectric conversion layer 4 is epitaxially grown as described below.

Light absorption N2: Composition: 11g1-XCdXte, x=0.
15 Forbidden band width: Eg#OeV Thickness: 5 pra Semi-insulating layer 3: Composition: CdTe Forbidden band width: Ug"il, 6eV Resistivity: 106Ω・cm Thickness: 20ttm Photoelectric conversion layer 4: Composition"'g+- +cCd, Te10//11 band: to #0.23~5 ttrm band:
x=0.3 forbidden band width: 10.1/II+ band: Eg#0.10eV
For 3 to 5 Jrm band: Eg#0.25 eV carrier concentration: 0.5 to 2 A separation region 6 is formed, and electrodes 5 facing each other are provided on the photoelectric conversion layer 4 with a distance of, for example, 50 pI11. For example, the area exposed between the electrodes 5 of the photoelectric conversion layer 4 is 50 um x 50 J! The area 4A of No. 11 is the light receiving area of each photodetecting element.

Comparing the amount of crosstalk between this embodiment and the corresponding conventional example under the same conditions, the amount of crosstalk is approximately 30% of that of the conventional example.
On the other hand, in this example, it decreased to 1/10 or less, demonstrating the effect of the present invention.

Comparing the present embodiment described above and the corresponding conventional example under the same conditions, it was found that, for example, while the crosstalk of the conventional example was approximately 30%, the amount of crosstalk was reduced to less than 1/1O in this example. The effects of the present invention were demonstrated.

Although the above explanation refers to a CdTe/Hg+-xCd)ITe-based semiconductor imaging device, for example, an infrared imaging device using a lead tellurium/lead tin tellurium (1'bTe/Pbl-XSn, Te) based semiconductor material, etc. It can be applied to any semiconductor material. Furthermore, the photodetecting element is not limited to the photoconductive type cited, but may be of the photovoltaic type.

〔Effect of the invention〕

As described above, according to the present invention, stray light within the base of a semiconductor imaging device is completely prevented, and the problem of crosstalk caused by this stray light is solved.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the present invention, FIG. 2 is a schematic diagram of an embodiment of the present invention, FIG. 3 is a schematic diagram of a conventional example, and FIG. 4 is an explanatory diagram of a conventional example. In the figure, l is a semi-insulating CdTe substrate, 2 is a 11g1-, cd, Te light absorption layer, 3 is a CdTe semi-insulating layer, 4 is a 11g1-XCdXTe photoelectric conversion layer, 48 is a light receiving area of a photodetecting element, 5 6 indicates the electrode, and 6 indicates the MtW region corresponding to the element amount. Trees and the dormitory dormitory 1-1-11, 1, 1, 1, 1, 1, 1, 1, 111, 111 Firmar guns θ

Claims (1)

[Claims] A semiconductor imaging device characterized in that a light absorption layer is provided behind a photoelectric conversion layer with a semi-insulating layer interposed therebetween.