JPH0525183B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to an infrared detector and a method of manufacturing the same, and particularly to a cold filter and a cold shield of an infrared detector and a method of forming the same.

(2) Technical background Cold filters and cold shields in infrared (wavelength approximately 2 to 15 μm) detectors are important components for suppressing background noise and improving the resolution (pixel separation) of infrared detectors. . Note that the cold filter mainly blocks infrared rays from objects around the detector, and the cold shield captures only infrared rays from the target to improve directivity.

Infrared detectors are used for industrial measurement, physical measurement, medical use,
It is a central device for infrared technology used for resource distribution and weather observation through remote sensing from artificial satellites. For example, in detectors made of quantum-type sensing elements formed using semiconductor device manufacturing technology, miniaturization and multi-element technology are progressing, and a two-dimensional array structure in which sensing elements are arranged two-dimensionally on a semiconductor substrate is progressing. has become the mainstream.

In such a two-dimensional array structure detector,
It is important to exclude background radiation from equipment around the detector and objects other than the target, and to prevent crosstalk between each infrared sensing element (pixel) to achieve low noise and reliable pixel separation. For this purpose, a cold shield corresponding to each pixel is provided.

In early infrared detectors, cold filter silicon (Si) or germanium (Ge)
Zinc sulfide (ZnS) and silicon oxide (SiO) on thin plates
The configuration consists of a non-reflective coating such as , or a multi-layered coating with wavelength selectivity, which is cooled and placed on the incident surface of the infrared detector element.On the other hand, the cold shield that determines the viewing angle is coated with non-reflective coating. It was made up of a separate metal plate with a predetermined opening. This configuration has the disadvantage that the detector configuration becomes complicated, and in particular cannot be adapted to multi-element detection elements or two-dimensional arrays.

(3) Conventional technology and problems Figure 1 shows the cold filter in the conventional technology.
This is a cross-sectional view of the main parts of an infrared detector equipped with a cold shield, in which reference numeral 1 indicates a semiconductor substrate, 2
indicates an infrared sensing element (pixel) formed on the semiconductor substrate 1.

On the other hand, the reference numeral 3 indicates a cold filter made of a silicon plate, for example, and inside the cold filter 3, band-shaped grooves formed at equal intervals corresponding to the pixels 2 are filled with a substance that is not transparent to infrared rays. A shield 4 is formed. The cold filter 3 on which the cold shield 4 is formed is adhered to the surface of the substrate 1 on which the pixels 2 are formed (separated in the figure for explanation), and such adhesion is applied to the surface of the substrate 1 on which the pixels 2 are formed. It was done by aligning it so that it was located in the middle.
The material of the cold filter 3 is selected depending on the detection wavelength; for example, silicon is used for wavelengths of 3 to 5 μm, and germanium is used for wavelengths of 8 to 12 μm.

By the way, in the past, background radiation was excluded and infrared rays from the target were detected by using the above-mentioned configuration, but it was difficult to accurately align the cold filter 3 when bonding it, especially when using a two-dimensional array configuration. When increasing the number of elements, there were problems such as the inability to achieve uniform sensitivity characteristics in all pixels due to positional deviation, and the complexity of the detector configuration.

(4) Purpose of the Invention In view of the above-mentioned conventional drawbacks, the present invention provides a cold filter and a cold shield for an infrared detector, which can cope with miniaturization of detection elements and multi-element by two-dimensional array, etc., and which have a simple configuration. The purpose is to provide.

(5) Structure of the Invention According to the present invention, a plurality of infrared detection elements are formed on one side of a semiconductor substrate, and the infrared detector receives light incident from the other side of the substrate. The one surface side of the semiconductor substrate is vertically divided into two halves between the infrared sensing elements, and a groove formed around the infrared sensing elements is filled with a material that is opaque to infrared rays. An infrared detector characterized in that the viewing angle θ of the infrared detecting elements determined by the distance S between the infrared detecting elements and the depth L of the groove is the same for a plurality of infrared detecting elements, and one surface of a semiconductor substrate. In manufacturing an infrared detector that forms a plurality of infrared sensing elements and receives light incident from the other surface, a semiconductor substrate on the side of the other incident light surface is provided with an infrared ray that passes through an intermediate portion of each infrared sensing element, This is achieved by providing a method for manufacturing an infrared detector, characterized in that a groove is formed so as to surround the periphery of the infrared rays, and the groove is filled with a material that is opaque to infrared rays.

(6) Examples of the invention Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a cross-sectional view of the main part of an infrared detector for explaining one embodiment of the present invention. 12 is an infrared sensing element formed on one surface of the substrate 11 by a conventional technique;
Reference numeral 13 denotes a cold shield formed by filling a material opaque to infrared rays into a groove dug toward the inside of the substrate 11 from the surface where the infrared sensing element 12 is not formed. It is formed so as to surround each infrared sensing element 12 so as to provide the same. Also, code 14 is ZnS or
Indicates an AR (Anti-Reflection) coat (anti-reflection film) made of SiO film, etc., or a multilayer film with infrared wavelength selectivity.

The formation of the cold shield 13 can be easily performed using micro three-dimensional processing technology in semiconductor manufacturing such as ion beam milling, for example,
The formation position is, for example, on a straight line that vertically bisects the space S between the sensing elements 12 (this alignment can be easily done using ordinary techniques), and the length L is set to prevent crosstalk between pixels and to prevent the sensing elements 12 from forming. It is determined as appropriate depending on the viewing angle θ determined in relation to the distance S. Note that in the latter case, the length L is the distance from the sensing element 12 in the groove forming direction, and is ultimately determined by the thickness of the sensing element substrate 11 when the interval S between the sensing elements 12 is fixed. Further, the substrate between the cold shields 13 plays the role of a cold filter.

With this configuration, the cold filter and the cold shield can be integrally formed on the sensing element substrate, and all the sensing elements 12 can see the same viewing angle θ, so that uniform sensing characteristics can be obtained. Note that in the above configuration, the sensing element substrate 1
It is possible to detect infrared rays incident on either side of 1.

FIG. 3 is a sectional view of the main part of an infrared detector for explaining another embodiment of the present invention. In this embodiment, an epitaxial layer is grown on a base material substrate, and a detection element is formed on this epitaxial layer. It can be applied when

To explain in more detail with reference to the same figure, for example,
A CdTe compound semiconductor substrate is used as a base material substrate (sensing element substrate) 15 that plays the role of a cold filter,
An epitaxial layer 16 made of a tertiary compound semiconductor crystal of mercury, cadmium, tellurium (HgCdTe), for example, is grown on one surface thereof, and infrared sensing elements 12 are arranged and formed on the epitaxial layer 16.

On the other hand, grooves are formed in the base substrate 15 according to the same positional relationship as in the above embodiment, and the grooves are filled with a material that is opaque to infrared rays to form the cold shield 13. A coat 14 is formed to constitute an infrared detector. In this embodiment as well, the positional relationship between the sensing element 12 and the cold shield 13 can be easily achieved using a normal technique (for example, double-sided mask aligner), and the viewing angle θ is determined by the distance between the sensing elements and the base material substrate 15. It is determined by the thickness (length of the cold shield 13). Note that the method for forming the HgCdTe epitaxial layer described above is already a known technique.

With the above configuration, it is possible to obtain a two-dimensional array infrared detector having a simple structure, reliable pixel separation, and uniform detection characteristics.

In the embodiments of the present invention described above, CdTe or HgCdTe compound semiconductors were used as the substrate material, but the scope of the present invention is not limited to this, and also extends to cases where other infrared transparent substrates are used. It is something. Further, the position where the cold shield is formed is not limited to the position shown in the above embodiment.

(7) Effects of the Invention As described in detail above, according to the present invention, a cold filter and a cold shield are integrated into an infrared detection element substrate, and the structure is simple and pixel separation can be performed reliably. Since the detector can be provided, it is possible to obtain an infrared detector with uniform detection characteristics even when the detection element is miniaturized and multi-element, which is highly effective in improving the reliability of the infrared detector.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the main part of a conventional infrared detector, and FIGS. 2 and 3 are sectional views of the main part of an infrared detector according to the present invention. 1 and 11 are sensing element substrates, 2 and 12 are infrared sensing elements, 3 is a cold filter, 4 and 13 are cold shields, 14 is an AR coat, 15 is a base material substrate, and 16 is an epitaxial layer.

Claims (1)

[Claims] 1. In an infrared detector in which a plurality of infrared detection elements 12 are formed on one surface of a semiconductor substrate 11 and receives light incident from the other surface of the substrate 11,
The space between the infrared sensing elements 12 is vertically divided into two on the one surface side of the semiconductor substrate 11, and a groove formed around the infrared sensing elements 12 is filled with a material 13 that is opaque to infrared rays. An infrared detector characterized in that the viewing angle θ of the infrared detecting elements 12 determined by the distance S between the infrared detecting elements and the depth L of the groove is the same for a plurality of infrared detecting elements 12. 2 The infrared sensing element 12 is a compound semiconductor substrate 1
The infrared detection device according to claim 1, wherein the groove formed in the epitaxial layer grown on one surface of the compound semiconductor substrate 5 and filled with a material 13 that is opaque to infrared rays is provided in the compound semiconductor substrate 15. vessel. 3. In manufacturing an infrared detector in which a plurality of infrared detection elements 12 are formed on one surface of a semiconductor substrate 11 and receives light incident from the other surface, each of the semiconductor substrate 11 on the other incident light surface side is Passing through the middle part of the infrared sensing element 12, the element 1
1. A method of manufacturing an infrared detector, comprising: forming a groove surrounding the periphery of the infrared detector 2, and filling the groove with a material 13 that is opaque to infrared rays.