JP2023123272A - infrared device - Google Patents

Abstract

To provide an infrared device with enhanced reliability.SOLUTION: An infrared device comprises: a substrate (1); a semiconductor lamination part that includes a first semiconductor layer (11) of a first conductivity type provided on a surface (1a) that is one surface of the substrate and having a flat part and a convex part, a second semiconductor layer (12) that is an active layer laminated on the convex part, and a third semiconductor layer (13) of a second conductivity type laminated on the second semiconductor layer, the convex part, the second semiconductor layer, and the third semiconductor layer forming a first mesa part (10), the flat part forming a second mesa part (20); a first contact hole (35) provided on a top face (T1) of the first mesa part; a second contact hole (36) provided on the flat part; and a first electrode (43) that exposes an exposure part (44) that is a part of the first mesa part and covers the whole of the first mesa part other than the exposure part. The exposure part includes a region between the first contact hole and the second contact hole.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to infrared devices.

As infrared devices, an infrared light receiving element that outputs a signal corresponding to received infrared light and an infrared light emitting element that emits infrared light according to input power are known. A quantum-type infrared light receiving element detects infrared rays by photocurrent generated by absorption of infrared rays by a semiconductor having a pn junction or a pin junction. An infrared light receiving element is sometimes called an infrared sensor. Quantum-type infrared light receiving elements are used, for example, as human sensors and non-contact temperature sensors that detect infrared rays emitted from the human body. The infrared light emitting element emits infrared light by applying voltage in the forward direction. An infrared light emitting element is sometimes called an infrared LED (light emitting diode). An infrared light receiving element and an infrared light emitting element may be used, for example, in an NDIR (non dispersive infrared) type gas sensor (for example, Patent Document 1). The NDIR gas sensor can measure the gas concentration using an infrared light receiving element that receives infrared light in the absorption wavelength band corresponding to the gas to be detected and an infrared light emitting element that emits infrared light in the absorption wavelength band.

JP 2004-271518 A Japanese Patent No. 5840408

Here, the infrared sensor of Patent Document 2 is of a mesa (PN stepped) type, and by covering the entire top surface and side surfaces of the mesa region with electrodes, the transmission of incident light from the back surface of the substrate is prevented. In recent years, infrared devices with large steps in the mesa region are sometimes manufactured, and there is a demand for a structure capable of improving reliability without covering the entire top surface and side surfaces with electrodes.

An object of the present disclosure made in view of such points is to provide an infrared device with improved reliability.

An infrared device according to one embodiment comprises:
a substrate;
A first semiconductor layer of a first conductivity type provided on a surface which is one surface of the substrate and having a flat portion and a convex portion, and a second semiconductor layer laminated on the convex portion and serving as an active layer. and a third semiconductor layer of a second conductivity type stacked on the second semiconductor layer, wherein the protrusion, the second semiconductor layer, and the third semiconductor layer a semiconductor lamination portion forming a first mesa portion with and forming a second mesa portion with the flat portion;
a first contact hole provided on the upper surface of the first mesa;
a second contact hole provided in the flat portion;
a first electrode that exposes an exposed portion that is a part of the first mesa portion and covers the entire first mesa portion excluding the exposed portion;
The exposed portion includes a region between the first contact hole and the second contact hole.

According to the present disclosure, it is possible to provide an infrared device with improved reliability.

FIG. 1 is a diagram showing a configuration example of an infrared device according to an embodiment of the present disclosure. FIG. 2 is a diagram illustrating a configuration example of an infrared device according to an embodiment of the present disclosure;

The infrared light receiving element 100 according to the first embodiment of the present disclosure will be described below with reference to the drawings. The infrared light receiving element 100 is an example of an infrared device and is a mesa type device. Here, the infrared light emitting device 200 can be configured with the same structure as the infrared light receiving device 100 described below. That is, the structure of the infrared light receiving element 100 described in this embodiment can be used as the structure of the infrared light emitting element 200 as it is. In other words, in this embodiment, the structure of these infrared devices will be described using the infrared light receiving element 100 as a representative.

In each figure described below, the same reference numerals are given to the parts corresponding to each other, and the description of the overlapping parts will be omitted as appropriate. Further, the present embodiment exemplifies the configuration for embodying the technical idea of the present disclosure, and does not specify the material, shape, structure, arrangement, dimensions, etc. of each part as follows. Various modifications can be made to the technical idea of the present disclosure within the technical scope defined by the claims.

FIG. 1 is a diagram showing a configuration example of an infrared light receiving element 100 according to this embodiment. 1 is a plan view of the infrared light receiving element 100, showing the mesa region of the infrared light receiving element 100 viewed from above. The upper diagram of FIG. 1 is a cross-sectional view of the infrared light receiving element 100 along AA shown in the lower diagram. As shown in FIG. 1, the infrared light receiving element 100 includes a substrate 1, a semiconductor laminate provided on one surface (hereinafter referred to as surface 1a) of the substrate 1, a first contact hole 35, and a second contact. a hole 36; The infrared light receiving element 100 also includes a first electrode 43 covering the first contact hole 35 and a second electrode 45 covering the second contact hole 36 . As indicated by the thick arrow in the upper diagram of FIG. 1, the infrared light receiving element 100 receives light from the surface (rear surface) opposite to the front surface 1a of the substrate 1 .

The semiconductor laminated portion includes a first mesa portion 10 and a second mesa portion 20 provided below the first mesa portion 10 on the surface 1a side of the substrate 1 . As shown in FIG. 1, the semiconductor lamination portion includes a first conductive type first semiconductor layer 11 having a flat portion 11a and a convex portion 11b, and a second semiconductor layer 11 which is an active layer laminated on the convex portion 11b. and a third semiconductor layer 13 of the second conductivity type laminated on the second semiconductor layer 12 . Photoelectric conversion is performed in the second semiconductor layer 12, which is an active layer. The first mesa portion 10 is formed by the convex portion 11 b, the second semiconductor layer 12 and the third semiconductor layer 13 . Further, the second mesa portion 20 is formed by the flat portion 11a.

Here, the word “upper” in the above description of “the active layer laminated on the convex portion 11b” includes the fact that the active layer is formed directly above the convex portion 11b. It also includes the case where another layer further exists between the active layer. When the term "upper" is used to describe the relationship between other layers, it has the same meaning. For example, another semiconductor may be included between the second semiconductor layer 12 and the third semiconductor layer 13 .

Conductivity type refers to either so-called n-type or p-type according to the type of carrier. Typically, the n-type semiconductor is an impurity semiconductor doped with a donor impurity such as phosphorus (P). A p-type semiconductor is an impurity semiconductor doped with an acceptor impurity such as boron (B). In this embodiment, from the viewpoint of improving the infrared transmittance by the Burstein-Moss effect, the first conductivity type is n-type and the second conductivity type is p-type. However, the combination is not limited to this, and the first conductivity type may be p-type and the second conductivity type may be n-type.

Materials for the first semiconductor layer 11, the second semiconductor layer 12, and the third semiconductor layer 13 are not limited. The first semiconductor layer 11, the second semiconductor layer 12 and the third semiconductor layer 13 may contain materials such as Al, P, Ga, As, In and Sb. Also, the ratio of each element can be adjusted as appropriate. As an example, the first semiconductor layer 11, the second semiconductor layer 12, and the third semiconductor layer 13 may be In compounds, which are compounds containing at least In.

The infrared light receiving element 100 also includes an insulating film 30 that continuously covers the first mesa portion 10 and the second mesa portion 20 . In this embodiment, the insulating film 30 covers the first mesa portion 10 and the second mesa portion 20 other than the first contact hole 35 and the second contact hole 36 . The infrared light receiving element 100 has a first electrode portion joined to the upper surface _T1 of the first mesa portion 10 through a first contact hole 35 provided in the insulating film 30 . As shown in the upper diagram of FIG. 1, the first electrode 43 covering the first contact hole 35 provided on the upper surface _T1 of the first mesa portion 10 is the first electrode 43 on the far side from the second contact hole . It extends to the side surface of the mesa portion 10 of 1. The first electrode 43 preferably covers 80% or more, more preferably 90% or more, and 100% of the side surface other than the side surface on the second contact hole 36 side. is more preferred. Here, the side surface on the side of the second contact hole 36 is a side surface having a surface facing the second contact hole 36, which is normally one side surface. are opposed to each other, the two side surfaces are the side surfaces on the second contact hole 36 side.

The infrared light receiving element 100 also has a second electrode portion joined to the upper surface of the second mesa portion 20 through a second contact hole 36 provided in the insulating film 30 . As shown in the upper diagram of FIG. 1 , the second electrode 45 covering the second contact hole 36 provided in the flat portion 11 a extends away from the first contact hole 35 . Here, the interface between the first mesa portion 10 and the second mesa portion 20 may be referred to as the lower surface of the first mesa portion 10 . In the upper diagram of FIG. 1, the lower surface of the first mesa portion 10 is indicated by broken lines. A first contact hole 35 is provided in the upper surface _T1 of the first mesa portion 10, and a second contact hole 36 is provided on the extension of the lower surface of the first mesa portion 10. As shown in FIG.

As shown in FIG. 1 , in the infrared light receiving element 100 according to this embodiment, the first electrode 43 exposes the exposed portion 44 that is part of the first mesa portion 10 . The first electrode 43 is configured to cover the entire first mesa portion 10 excluding the exposed portion 44 . Exposed portion 44 includes a region between first contact hole 35 and second contact hole 36 . Here, other portions of the first mesa portion 10 may be further exposed. That is, the exposed portion 44 should include at least the region between the first contact hole 35 and the second contact hole 36 . In this embodiment, the exposed portion 44 extends from the side surface of the first mesa portion 10 to the top surface _T1 . The infrared light receiving element 100 according to the present embodiment has the exposed portion 44, thereby reducing the risk of short-circuiting between the electrodes, that is, enhancing insulation. Therefore, the reliability of the quality of the infrared light receiving element 100 is enhanced. Here, in order to obtain sufficient insulation, the first electrode 43 covering the first contact hole 35 is spaced from the second electrode 45 covering the second contact hole 36 by at least 3 μm. preferably. The exposed portion 44 may be provided only on the side surface of the first mesa portion 10 between the first contact hole 35 and the second contact hole 36, and may be provided on the upper surface _T1 of the first mesa portion 10. However, it is preferable that it is provided at least on the side surface of the first mesa portion 10, and extending from the side surface of the first mesa portion 10 to the top surface _T1 enhances the insulation. It is preferable because it can be increased.

Here, in the present embodiment, the exposed portion 44 extends to the upper surface _T1 of the first mesa portion 10, but from the viewpoint of preventing transmission of incident light from the back surface of the substrate 1, the exposed portion 44 should not be too large. is preferred. For example, it is preferable that 80% or more of the area of the upper surface _T1 of the first mesa portion 10 is covered with the first electrode 43 . At this time, since the side surface and 80% or more of the upper surface _T1 of the first mesa portion 10 other than the exposed portion 44 are covered with the first electrode 43, it is possible to greatly prevent the transmission of incident light.

Here, the area of the first contact hole 35 is determined according to the size of the upper surface _T1 of the first mesa portion 10, and is not particularly limited. However, from the viewpoint of reducing the contact resistance, the area of the first contact hole 35 is preferably 40% or more of the area of the upper surface _T1 of the first mesa portion 10 in plan view.

The infrared light receiving element 100 according to this embodiment may be manufactured by the following steps. First, a first conductive type first semiconductor layer 11 is formed on the surface 1 a of the substrate 1 . An intrinsic second semiconductor layer 12 is then formed on the first semiconductor layer 11 . A third semiconductor layer 13 of the second conductivity type is formed on the second semiconductor layer 12 . In other words, the first semiconductor layer 11, the second semiconductor layer 12, and the third semiconductor layer 13 are formed on the substrate 1 in this order. The film formation of the first semiconductor layer 11, the second semiconductor layer 12, and the third semiconductor layer 13 may be performed continuously, for example, in a chamber of an epitaxial growth apparatus while maintaining a preset degree of vacuum. .

Next, a resist pattern is formed on the third semiconductor layer 13 using a photolithographic technique. Before the masking step of forming a resist pattern mask, a hard mask such as SiO ₂ is formed on the third semiconductor layer 13 to prevent the resist pattern from directly contacting the third semiconductor layer 13 . good.

Next, using the resist pattern as a mask, the protrusions 11b of the third semiconductor layer 13, the second semiconductor layer 12 and the first semiconductor layer 11 are sequentially etched. Thereby, the first mesa portion 10 is formed.

Here, since the infrared light receiving element 100 according to the present embodiment has the exposed portion 44, stripping liquid for stripping the resist easily enters. When the exposed portion 44 extends up to the upper surface _T1 of the first mesa portion 10 as in the present embodiment, the effect of making it easier for the stripping liquid to enter is enhanced. In addition, when the steps in the mesa region become large, the process of removing the resist in the manufacturing of the infrared light receiving element 100 becomes difficult. Improve yield. Therefore, the mass productivity and reliability of the infrared light receiving element 100 are enhanced.

Here, when forming the first mesa portion 10, as an etching gas for etching the protrusions 11b of the third semiconductor layer 13, the second semiconductor layer 12 and the first semiconductor layer 11, a halogen gas is used. , a gas containing halogen in its composition (hereinafter referred to as a halogen-based gas), or a mixed gas thereof may be used. Examples of halogen gas include chlorine gas (Cl ₂ ). Examples of halogen-based gases include hydrogen chloride gas (HCl) and hydrogen bromide gas (HBr). Since the etching gas does not contain an oxidizing gas such as oxygen gas, the selectivity between the resist and the semiconductor layer is improved, and the loss of the resist during the etching process can be prevented.

As described above, the reliability of the infrared light receiving element 100 according to the present embodiment can be improved by the above configuration.

Further, the infrared light emitting element 200 according to the present embodiment, which has the same structure as the infrared light receiving element 100, has the same effects as the infrared light receiving element 100.

Although the embodiments of the present disclosure have been described with reference to drawings and examples, it should be noted that various variations or modifications can be easily made by those skilled in the art based on the present disclosure. Therefore, it should be noted that these variations or modifications are included within the scope of this disclosure. For example, functions included in each component can be rearranged so as not to be logically inconsistent, and multiple components can be combined into one or divided.

In the above embodiment, the shape of the first mesa portion 10 is pentagon in plan view, but the shape of the first mesa portion 10 is not limited. For example, when the shape of the first mesa portion 10 is a polygon having N corners in plan view, at least (N/2) corners should be covered with the first electrode 43 . In the example of FIG. 1 (N=5), the first electrodes 43 cover three corners, which is (N/2) or more.

FIG. 2 shows an infrared device in which the first mesa portion 10 is square (N=4) in plan view. Similar to FIG. 1, the lower drawing in FIG. 2 is a plan view, and the upper drawing is a cross-sectional view along AA in the lower drawing. In the example of FIG. 2, the cross-sectional structure of the infrared device is the same as in FIG. As shown in the lower diagram of FIG. 2, two corners of the first mesa portion 10 are covered with the first electrode 43 . The infrared device shown in FIG. 2 can also be highly reliable, similar to the above embodiments.

Reference Signs List 1 substrate 1a surface 10 first mesa portion 11 first semiconductor layer 11a flat portion 11b convex portion 12 second semiconductor layer 13 third semiconductor layer 20 second mesa portion 30 insulating film 35 first contact hole 36 Second contact hole 43 First electrode 44 Exposed portion 45 Second electrode 100 Infrared light receiving element 200 Infrared light emitting element

Claims (6)

a substrate;
A first semiconductor layer of a first conductivity type provided on a surface which is one surface of the substrate and having a flat portion and a convex portion, and a second semiconductor layer laminated on the convex portion and serving as an active layer. and a third semiconductor layer of a second conductivity type stacked on the second semiconductor layer, wherein the protrusion, the second semiconductor layer, and the third semiconductor layer a semiconductor lamination portion forming a first mesa portion with and forming a second mesa portion with the flat portion;
a first contact hole provided on the upper surface of the first mesa;
a second contact hole provided in the flat portion;
a first electrode that exposes an exposed portion that is a part of the first mesa portion and covers the entire first mesa portion excluding the exposed portion;
The infrared device, wherein the exposed portion includes a region between the first contact hole and the second contact hole. The infrared device according to claim 1, wherein the exposed portion extends from the side surface to the top surface of the first mesa portion. 3. The infrared device according to claim 1, wherein the area of said first contact hole is 40% or more of the area of said upper surface of said first mesa portion in plan view. 4. The first electrode covering the first contact hole is spaced from the second electrode covering the second contact hole by at least 3 [mu]m. Infrared device as described in . The infrared device according to any one of claims 1 to 4, wherein 80% or more of the area of the upper surface of the first mesa portion is covered with the first electrode. 2. From claim 1, wherein the shape of the first mesa portion is a polygon having N corners in plan view, and at least (N/2) corners are covered with the first electrode. 6. The infrared device according to any one of 5.

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