JPH0677522A - Light emitting/light detecting element and their manufacture - Google Patents

Abstract

PURPOSE:To realize excellent light emitting/light detecting elements, by forming a semiconductor DBR reflecting film so as to surround a PN junction part which film is formed by laminating several tens layers of two kinds of thin films different in refractive index. CONSTITUTION:On the surfaces of recessed parts formed on a substrate 101, the following are laminated in order; a first buffer layer 102 composed of N- GaAs or the like, a semiconductor DBR reflecting film layer 103 which is formed by laminating several tens layers of thin films which are composed of GaAs/ AlAs or the like and different in refractive index, a second buffer layer 104, and an epitaxial layer 105 composed of low defective N-GaAs or the like. In a selected region of the epitaxial layer 105, a diffusion layer 106 having impurities of a conductivity type opposite to the epitaxial layer 105 is formed by selective diffusion using a diffusion mask 108. A PN junction part 107 is formed between the epitaxial layer 105 and the diffusion layer 106. Hence a light emitting element of high luminous efficiency and a light detecting element of high photoelectric conversion efficiency can be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting element used for a light source of an LED printer, a light emitting element for a sensor,
The present invention relates to a structure of a light receiving element and a light emitting / light receiving element used for optical communication and the like, and a manufacturing method thereof.

[0002]

2. Description of the Related Art FIG. 5 is a sectional view of a conventional light emitting device. This light-emitting element has a buffer layer 5 on a certain conductivity type substrate 501.
02, and an epitaxial layer 503 of the same conductivity type as the substrate 501 is formed on the buffer layer 502. Impurity diffusion is performed using the diffusion mask 505 formed on the surface as a mask to form a diffusion layer 504 of the opposite conductivity type in the epitaxial layer 503. As a result, a PN junction is formed between the epitaxial layer 503 and the diffusion layer 504.

The structure of the light receiving element is also basically the same as that of the light emitting element. In the conventional light emitting element or light receiving element, a first epitaxial layer of the same conductivity type as this substrate is formed on a substrate of a certain conductivity type. And a diffusion layer of opposite conductivity type was formed on the first epitaxial layer, or a second epitaxial layer of opposite conductivity type was formed on the first epitaxial layer. Due to the PN junctions of the two conductivity type regions, current is converted into light in the light emitting element and light is converted into current in the light receiving element.

[0004]

However, the above-mentioned light emitting element and light receiving element have the following problems. In the conventional light emitting device, as shown in the cross-sectional view of FIG. 6, the light emitted in the surface direction from the PN junction formed by the diffusion layer 504 of the opposite conductivity type to the epitaxial layer 503 which is the light emitting portion. Only E1 could be used, and the light E2 emitted toward the back surface could not be used. Therefore, in order to obtain a desired light output, it is necessary to also supply a current for light that is wastefully radiated in the back surface direction, which shows the relationship between the supplied current and the light output. Was not good.

Also, in the conventional light receiving element, as shown in the sectional view of FIG.
Not all the light S1 incident on the PN junction formed by the diffusion layer 504 of the opposite conductivity type to that of 503 is converted into a current, but a part of the incident light S1 is transmitted light S2 transmitted through the PN junction.
It was used in vain. Further, the incident light that has entered the diffusion mask 505 portion in the outer peripheral region of the PN junction portion is also wasted without being converted into a current at the PN junction portion. As a result, the photoelectric conversion efficiency showing the relationship between the supplied light and the current output was not good.

As described above, according to the present invention, in the light emitting element, only a part of the light generated in the PN junction is extracted, and in the light receiving element, the PN junction and its periphery are taken out. An object of the present invention is to provide an excellent light-emitting / light-receiving element and a method for manufacturing the same, which solves the problem that only a part of the light incident on is converted into a current.

[0007]

In order to solve the above-mentioned problems, the present invention provides a light-emitting / light-receiving element in which a concave portion formed on the surface of a substrate and a concave portion formed in the concave portion have different refractive indexes.
Semiconductor DBR (Distribu
ted Bragg Reflecton) a reflection film, and a first conductivity type formed on the semiconductor DBR reflection film in the recess.
And a second semiconductor region formed in the first semiconductor region and having a conductivity type opposite to that of the first conductivity type, the first semiconductor region and the second semiconductor region being P
It is designed to be N-joined.

In this light emitting / receiving element, the concave portion is formed in a conical shape or a trapezoidal shape having a side wall portion and a bottom portion. Alternatively, in the method for manufacturing a light-emitting / light-receiving element, a step of selectively forming a resist pattern on a substrate and using the resist pattern as a mask,
Etching the substrate to form a recess in the substrate; forming a semiconductor DBR reflective film on the substrate including the recess; and having a first conductivity type on the semiconductor DBR reflective film. Forming a semiconductor region of 1;
The first semiconductor region and the semiconductor DBR reflection film are polished, and the first semiconductor region and the semiconductor DBR reflection film are present in a state where the first semiconductor region and the semiconductor DBR reflection film are present in at least the recess. Planarizing the surface of the substrate including a film, and forming a second semiconductor region of a conductivity type opposite to the first conductivity type in the first semiconductor region in the recess, And a step of forming a PN junction between the region and the second semiconductor region.

Alternatively, in the light emitting / receiving element, a step of selectively forming a resist pattern on the substrate, a step of etching the substrate using the resist pattern as a mask, and forming a recess in the substrate, Forming a semiconductor DBR reflective film on the substrate including the recess;
A first conductive type having a first conductivity type on the semiconductor DBR reflective film;
And a second semiconductor region having a conductivity type opposite to that of the first conductivity type is continuously formed on the first semiconductor region by epitaxial growth. A step of forming a pn junction in the second semiconductor region, polishing the first and second semiconductor regions and the semiconductor DBR reflection film, and at least the recesses in the first and second semiconductor regions and the semiconductor DBR. The step of planarizing the surface of the substrate including the first and second semiconductor regions and the semiconductor DBR reflective film is performed in the state where the reflective film exists.

Alternatively, in the light emitting / receiving device, a step of selectively forming a resist pattern on the surface of the semiconductor substrate having the first conductivity type, and etching the substrate surface using the resist pattern as a mask, A step of forming a trapezoidal convex portion on a substrate surface, a step of forming a semiconductor DBR reflective film on the substrate surface including the convex portion, and a step of forming a support substrate on the semiconductor DBR reflective film. Polishing the back surface of the semiconductor substrate, and flattening the back surface of the support substrate including the semiconductor substrate and the semiconductor DBR reflective film in a state where the semiconductor substrate and the semiconductor DBR reflective film are present at least in the convex portion. And forming a first semiconductor region of a conductivity type opposite to that of the first conductivity type on the semiconductor substrate in the convex portion, and connecting the semiconductor substrate and the first semiconductor region with a PN contact. And performs the step of.

[0011]

In the light emitting device of the present invention, the semiconductor DBR reflection film in which several thin films of two kinds having different refractive indexes are stacked is provided so as to surround the PN junction. Not only the light radiated in the front surface direction from the PN junction portion, but also the light radiated in the rear surface direction is reflected by the semiconductor DBR reflective film layer and radiated in the front surface direction.

The light receiving element of the present invention is a semiconductor DB.
Since the R reflection film is provided so as to surround the PN junction portion, the light transmitted through the PN junction portion of the light incident on the PN junction portion, which is the light receiving portion in the light receiving state, is also a semiconductor DBR reflection film. It becomes possible to reflect on the layer and then re-enter the PN junction. Further, incident light that has entered the outer peripheral region of the PN junction can be reflected by the semiconductor DBR reflective film layer and enter the PN junction.

[0013]

FIG. 1 is a sectional view showing the structure of a light emitting / receiving element according to the first embodiment of the present invention, and FIG.
FIG. 6 is a process cross-sectional view showing the method for manufacturing the light receiving element. The present invention can be applied to both a light emitting element and a light receiving element, and the structure described in the embodiments can solve the problems of the conventional light emitting element and the light receiving element. Therefore, when there is a light emitting / light receiving element in this specification,
The light receiving element is a light emitting element that converts current into light at the PN junction to emit light, a light receiving element that converts light received at the PN junction into current, and an element capable of performing the above light emission or light reception depending on the case. , These are generic terms.

The light emitting / receiving element shown in FIG.
A recess is formed on a substrate 101 made of GaAs or the like having a specific conductivity type, and n-GaAs is formed on the surface of the recess.
A first buffer layer 102 made of GaAs / AlAs, etc., a semiconductor DBR reflective film layer 103 made of GaAs / AlAs etc. and having several tens of thin films of different types stacked, a second buffer layer 104 made of n-GaAs, etc. Epitaxial layers 105 made of deficient n-GaAs or the like are sequentially stacked. Then, in the selected region of the epitaxial layer 105,
By selective diffusion using the diffusion mask 108, a diffusion layer 106 having impurities of a conductivity type opposite to that of the epitaxial layer 105 is formed, and a PN junction 107 is formed on the junction surface between the epitaxial layer 105 and the diffusion layer 106. .

A method of manufacturing the light emitting / receiving device of the first embodiment will be described with reference to the process sectional views shown in FIG. First, Figure 2
As shown in (a), a resist pattern 109 is formed on a substrate 101 having a specific conductivity type such as n-GaAs.
To form. Next, as shown in FIG. 2B, the substrate 101 is etched into a conical shape or a trapezoidal shape having a side wall portion and a bottom portion using the resist pattern 109 as a mask.

Next, as shown in FIG. 2C, the MBE method or MOCV method is performed on the substrate 101 from which the resist pattern 109 has been removed.
The first buffer layer 102 made of n-GaAs or the like and the semiconductor DBR made of GaAs / AlAs or the like by the D method or the like.
Reflection film layer 103, second buffer layer 1 made of n-GaAs, etc.
04, and the epitaxial layer 105 made of low-deficiency n-GaAs or the like is sequentially epitaxially grown.

Next, as shown in FIG. 2D, the first buffer layer 102, the semiconductor DBR reflective film layer 103, the second buffer layer 104, and the epitaxial layer 10 laminated on the surface of the substrate 101.
5 is polished and flattened. The amount of polishing at this time can be set arbitrarily, and even if the upper portion of the recess is polished and removed, the effect of the present invention can be obtained as long as the lower portion of the recess remains.

Next, as shown in FIG. 2E, an insulating film 110 is formed on the surface. Next, as shown in FIG. 2F, the insulating film 110 is patterned according to the pattern of the substrate to form a diffusion mask 108 having a diffusion window.

Next, as shown in FIG. 2G, a diffusion mask
An impurity having a conductivity type opposite to that of the epitaxial layer 105 is diffused into the epitaxial layer 105 through the diffusion window 108 to form a diffusion layer 106. As a result, the PN junction portion 107 is formed on the junction surface between the epitaxial layer 105 and the diffusion layer 106.

In the light emitting / receiving device of the present invention manufactured by the manufacturing method of the first embodiment described above, the function of the semiconductor DBR reflective film layer 103 is shown in FIGS. 8 and 9 for each of the light emitting device and the light receiving device. Will be explained.

FIG. 8 is a cross-sectional view showing a light emitting state of the light emitting element of the present invention. Not only the light E1 emitted in the front direction but also the back direction is emitted from the PN junction portion 107 which is a light emitting portion. The emitted light E2 can also be reflected by the semiconductor DBR reflection film layer 103 and emitted in the surface direction.

FIG. 9 is a cross-sectional view showing the light receiving state of the light receiving element of the present invention. Of the light S1 incident on the PN junction portion 107 which is the light receiving portion, the transmitted light S2 transmitted through the PN junction portion 107. Is reflected on the semiconductor DBR reflection film layer 103, and again P
It becomes possible to enter the N-junction 107. Furthermore, PN
Incident light incident on the outer peripheral area of the junction 107 is also detected by the semiconductor DBR.
The light can be reflected by the reflective film layer 103 and incident on the PN junction 107.

FIGS. 3 and 4 are cross-sectional views showing the second and third embodiments of the manufacturing method of the present invention, respectively, and the same components as those in FIGS. 1 and 2 are designated by the same reference numerals. The light emitting / receiving element of the second embodiment shown in FIG.
In the same manner as in the embodiment of Example 1, after forming a laminated structure including the first buffer layer 102, the semiconductor DBR reflective film layer 103, the second buffer layer 104, and the epitaxial layer 105 on the substrate 101, the substrate 1
The 01 side is also polished, impurities are diffused in this substrate 101,
The PN junction 107 is formed.

The manufacturing method of the second embodiment will be described below. First, a resist pattern 109 is formed on the surface of the substrate 101 having a specific conductivity type. At this time, it should be noted that, contrary to the manufacturing method of the first embodiment, the PN junction portion 107 is formed below the region where the resist pattern 109 exists. That is, in the first embodiment, the resist pattern 109 having an opening at the portion where the recess is formed.
Is formed on the surface of the substrate 101, in the second embodiment, a resist pattern 109 having an island-shaped pattern is formed on the surface of the substrate 101 in the portion where the trapezoidal protrusion is formed.

Next, using the resist pattern 109 as a mask, the surface of the substrate 101 is etched so that trapezoidal protrusions remain. Next, on the surface of the substrate 101 from which the resist pattern 109 has been removed, the first buffer layer 102 and the semiconductor DB
R reflection film layer 103, second buffer layer 104, epitaxial layer
105 are epitaxially grown in order.

Next, the epitaxial layer 105 is formed on the supporting substrate 205.
Therefore, the surface is polished and flattened. The amount of polishing at this time may be smaller than that in the case of the first embodiment. Next, the back surface of the substrate 101 is polished, and the substrate 101 is removed leaving the trapezoidal region. The amount of polishing at this time can be set arbitrarily, and even if the lower portion of the trapezoidal region is polished and removed, the effect of the present invention can be obtained if the upper portion of the trapezoidal region remains.

Next, a diffusion mask 108 having a diffusion window is formed, and an impurity having a conductivity type opposite to that of the substrate 101 is diffused into the substrate 101 through the diffusion window of the diffusion mask 108 to form a diffusion layer 106. As a result, on the joint surface between the substrate 101 and the diffusion layer 106,
The PN junction 107 is formed. By using the manufacturing method of the second embodiment, the semiconductor DBR reflective film layer can be easily processed into a trapezoidal shape. If the semiconductor DBR reflective film layer has a trapezoidal shape having a side wall and a bottom, the semiconductor DBR reflective film layer exists in parallel below the light emitting part or the light receiving part of the light emitting / receiving element. It becomes easy to adjust the reflection direction of the light reflected by the layer.

The light emitting / receiving device of the third embodiment shown in FIG. 4 is one in which layers of opposite conductivity type are successively laminated by epitaxial growth to form a PN junction. This again 3
In the light-emitting / light-receiving element of this embodiment, a recess is formed on the substrate 101 having a specific conductivity type, and the first recess is formed on the surface of the recess.
Buffer layer 102, semiconductor DBR reflective film layer 103, second buffer layer 104, epitaxial layer 105, and epitaxial layer
A second epitaxial layer 206 having a conductivity type opposite to that of 105 is sequentially stacked. Then, P is formed on the junction surface between the epitaxial layer 105 and the second epitaxial layer 206 of the opposite conductivity type.
The N-junction 107 is formed.

A method of manufacturing the light emitting / receiving element of the third embodiment will be described below. First, the substrate 10 having a specific conductivity type
A resist pattern 109 is formed on 1. Next, using this resist pattern as a mask, the substrate 101 is etched into a conical shape or a trapezoidal shape.

Next, the substrate 10 from which the resist pattern has been removed
The first buffer layer 102 and the semiconductor DBR reflective film layer 10 on the first
3, second buffer layer 104, epitaxial layer 105, second epitaxial layer 206 having a conductivity type opposite to that of the epitaxial layer 105
Are sequentially epitaxially grown.

Next, the first buffer layer 102, the semiconductor DBR reflective film layer 103 and the second buffer layer which are laminated on the surface of the substrate 101.
The 104, the epitaxial layer 105, and the second epitaxial layer 206 are polished and planarized.

As a result of the above, the epitaxial layer 105 and the second
A PN junction 107 is formed between the epitaxial layer 206 and the epitaxial layer 206. By using the manufacturing method of the third embodiment, it is not necessary to form a diffusion mask for selectively diffusing the impurities, and the process can be simplified.

[0033]

As described above in detail, according to the present invention, the semiconductor DBR reflection film is provided in the conical shape or the trapezoidal shape below the PN junction part of the light receiving / light emitting element which becomes the light receiving part or the light emitting part. Therefore, in the light emitting element, the light emitted from the PN junction portion, which is the light emitting portion, toward the back surface can be reflected on the semiconductor DBR reflection film and extracted on the front surface.

Also in the light receiving element, the transmitted light that has passed through the PN junction, which is the light receiving portion, can be reflected by the semiconductor DBR reflection film and enter the PN junction again. Further, the incident light incident on the outer peripheral region of the PN junction can also be reflected on the semiconductor DBR reflection film and incident on the PN junction.

Therefore, it becomes possible to form a light emitting element having a high luminous efficiency and a light receiving element having a high photoelectric conversion efficiency.

[Brief description of drawings]

FIG. 1 is a sectional view showing the structure of a first embodiment of the present invention.

FIG. 2 is a process sectional view showing the manufacturing method of the first embodiment of the present invention.

FIG. 3 is a sectional view showing the structure of the second embodiment of the present invention.

FIG. 4 is a sectional view showing the structure of the third embodiment of the present invention.

FIG. 5 is a sectional view showing a structure of a conventional light emitting / receiving element.

FIG. 6 is a cross-sectional view showing a light emitting state of a conventional light emitting element.

FIG. 7 is a cross-sectional view showing a light receiving state of a conventional light receiving element.

FIG. 8 is a cross-sectional view showing a light emitting state of the light emitting device of the present invention.

FIG. 9 is a cross-sectional view showing a light receiving state of the light receiving element of the present invention.

[Explanation of symbols]

 101 substrate 102 first buffer layer 103 semiconductor DBR reflective film 104 second buffer layer 105 epitaxial layer 106 diffusion layer 107 PN junction 108 diffusion mask 109 resist pattern 110 insulating film 205 support substrate 206 second epitaxial layer E1 PN of light emitting element Emitted light from the junction to the front side E2 Light emitted from the PN junction of the light emitting element to the back side S1 Light incident from the outside to the PN junction of the light receiving element S2 Light transmitted through the PN junction of the light receiving element

Claims (5)

[Claims] 1. A substrate, a recess formed in the surface of the substrate, a semiconductor DBR reflective film formed in the recess, and a first conductivity type formed on the semiconductor DBR reflective film in the recess. A first semiconductor region and a second semiconductor region formed in the first semiconductor region and having a conductivity type opposite to that of the first conductivity type, wherein the first semiconductor region and the second semiconductor region are A light emitting / light receiving element characterized by having a PN junction. 2. The light emitting / receiving element according to claim 1, wherein the recess has a conical shape or a trapezoidal shape having a side wall portion and a bottom portion. 3. A step of selectively forming a resist pattern on a substrate; b) a step of etching the substrate with the resist pattern as a mask to form a concave portion in the substrate; and c) the concave portion. Forming a semiconductor DBR reflective film on the substrate including d), d) forming a first semiconductor region having a first conductivity type on the semiconductor DBR reflective film, and e) the first semiconductor region. The semiconductor region and the semiconductor DBR reflective film are polished, and the first semiconductor region and the semiconductor DBR reflective film are present in at least the recess,
Planarizing the surface of the substrate including the semiconductor region and the semiconductor DBR reflective film, and f) a second semiconductor having a conductivity type opposite to that of the first conductivity type in the first semiconductor region in the recess. A method of manufacturing a light emitting / receiving element, comprising: forming a region and forming a PN junction between the first semiconductor region and the second semiconductor region. 4. A step of selectively forming a resist pattern on a substrate; b) a step of etching the substrate using the resist pattern as a mask to form a concave portion in the substrate; and c) the concave portion. Forming a semiconductor DBR reflective film on the substrate including d), d) forming a first semiconductor region having a first conductivity type on the semiconductor DBR reflective film, and e) the first semiconductor region. A step of continuously forming a second semiconductor region having a conductivity type opposite to that of the first conductivity type on the semiconductor region by epitaxial growth, and forming a pn junction between the first semiconductor region and the second semiconductor region; f) the first and second semiconductor regions and the semiconductor DBR
The reflective film is polished, and at least the first and second semiconductor regions and the semiconductor DBR reflective film are present in at least the recess, and the first and second semiconductor regions and the semiconductor D are formed.
And a step of planarizing the surface of the substrate including the BR reflective film. 5. A step of selectively forming a resist pattern on the surface of a semiconductor substrate having the first conductivity type; and b) etching the substrate surface using the resist pattern as a mask to form a table on the substrate surface. Forming a convex portion having a shape; c) forming a semiconductor DBR reflective film on the surface of the substrate including the convex portion; and d) forming a support substrate on the semiconductor DBR reflective film. E) polishing the back surface of the semiconductor substrate, and flattening the back surface of the support substrate including the semiconductor substrate and the semiconductor DBR reflection film in a state where the semiconductor substrate and the semiconductor DBR reflection film are present at least in the convex portion. F) forming a first semiconductor region of a conductivity type opposite to that of the first conductivity type on the semiconductor substrate in the convex portion, and forming a PN junction between the semiconductor substrate and the first semiconductor region. Manufacturing method of the light emitting and receiving element; and a that step.