JP2002185036A - Semiconductor light-emitting element and semiconductor light-emitting device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor light-emitting element for obtaining output light, having sufficiently uniform optical output distribution within a light beam diameter at the time of passing through a lens, and improving the manufacturing efficiency and a semiconductor light-emitting device using it. SOLUTION: This semiconductor light-emitting device is provided with a light-emitting diode 1 having a semiconductor base body 10 for which a p-type semiconductor layer 11 and an n-type semiconductor layer 12 are laminated, a first electrode 21 and a second electrode 22, a package 5 storing the light- emitting diode 1, and a lens member 6. The semiconductor base body 10 is turned to a mesa shape provided with a slope 15 satisfying the condition that the ratio d2/d1 of a mesa depth to the depth of a p-n junction be 2<=d2/d1<=4 or the condition that the mesa depth d2 from a first main surface 13 be 25 μm<=d<=45 μm or the mesa depth d2-d1 from the p-n junction be 13 μm<=d2-d1<=32 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor light emitting device and a semiconductor light emitting device using the same.

[0002]

2. Description of the Related Art In an optical sensor such as a distance sensor or an angle sensor for optically detecting a distance or an angle, a semiconductor light emitting device having a semiconductor light emitting element such as a light emitting diode (LED) is used as a light source. (For example,
See JP-A-6-45650). In the semiconductor light emitting device used for such an optical sensor, depending on the use of each sensor and the resolution required for detecting distance, angle, etc., the output light amount and light output distribution of the output light are fixed. It is necessary to satisfy the light output condition.

[0003] For example, a transmission type optical encoder (rotary encoder) which is an angle sensor for optically detecting an angle.
Thus, in addition to the required output light quantity being ensured with respect to the output light supplied from the semiconductor light emitting device as the light source, (1) the collimated light whose light output direction is substantially parallel within the light beam diameter is obtained. It is required as a suitable light output condition that certain conditions are satisfied and that (2) a substantially uniform light output distribution is obtained within the light beam diameter.

[0004] Further, since it is difficult to realize the above condition (1) with a light emitting element alone, a lens is usually combined with the light emitting element. However, the light emitting region of the light emitting element has a width, and light is output not only from the central part of the element but also from the peripheral part of the element. However, in a lens designed to collimate light from the central part of the element, the element Sufficient parallelism cannot be obtained for light from the periphery. Therefore, in order to increase the degree of parallelism of the light passing through the lens, it is required to reduce the light beam diameter of the semiconductor light emitting element alone.

[0005]

The above-mentioned light output conditions suitable for a transmission optical encoder and the like are as follows.
For example, the semiconductor light emitting device is configured to simultaneously and sufficiently satisfy the respective light output conditions, such as when the light output distribution within the light beam diameter is not uniform when the light is made to pass through a lens to form collimated light. It is difficult.

As an example of a semiconductor light emitting device conventionally used as a light source in a transmission type optical encoder, there is one in which an LED chip as a semiconductor light emitting element is installed in a package having a cup-shaped reflecting surface. In such a semiconductor light emitting device, a large amount of output light is obtained by the light emitted from the side surface of the LED chip being reflected by the cup-shaped reflective surface and output to the outside. However, when the reflection surface outside the LED chip is used for condensing light as described above, there is a problem that the parallelism of the output light deteriorates.

Further, there is a type in which the light emitting surface itself of the LED chip has a dome shape and functions as a lens, emits light having a small light beam diameter, and outputs collimated light through the lens. However, such an LED chip has a complicated manufacturing process because the semiconductor chip must be etched into a dome shape,
Its manufacturing efficiency is low. For this reason, it is difficult to supply a sufficient number of semiconductor light emitting devices, and there are problems such as high cost of the semiconductor light emitting devices.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and when passing through a lens, it is possible to obtain output light having a sufficiently uniform light output distribution within the light beam diameter. It is another object of the present invention to provide a semiconductor light emitting element whose manufacturing efficiency is improved and a semiconductor light emitting device using the same.

[0009]

In order to achieve such an object, a semiconductor light emitting device according to the present invention has the following features.
A semiconductor substrate in which a first semiconductor layer having a conductivity type and a second semiconductor layer having a second conductivity type are stacked, and a pn junction is formed by a junction surface between the first semiconductor layer and the second semiconductor layer; A) a first electrode formed on a first main surface from which light from inside the semiconductor substrate is emitted, on a surface of the semiconductor substrate on the first semiconductor layer side; and (3) a surface of the semiconductor substrate on the second semiconductor layer side. A second main surface formed on the second main surface opposite to the first main surface.
(4) the semiconductor substrate has a mesa shape in which an inclined surface extending from the first main surface to a side surface is formed at an outer edge portion of the first main surface, and the semiconductor substrate has an inclination with respect to the thickness of the first semiconductor layer. The ratio of the mesa depth of the surface is 2 or more and 4 or less.

Alternatively, the semiconductor light emitting device according to the present invention comprises: (1) a first semiconductor layer having a first conductivity type;
A semiconductor substrate in which a second semiconductor layer having a conductivity type is laminated and a pn junction is formed by a junction surface between the first semiconductor layer and the second semiconductor layer; and (2) a surface of the semiconductor substrate on the first semiconductor layer side. A first electrode formed on a first main surface from which light from the inside of the semiconductor substrate is emitted; and (3) a first electrode on the second semiconductor layer side of the semiconductor substrate opposite to the first main surface. (4) the semiconductor substrate has a mesa shape in which an inclined surface extending from the first main surface to the side surface is formed at an outer edge portion of the first main surface. The mesa depth of the inclined surface from the first main surface is 25 μm or more and 45 μm or less, or the mesa depth of the inclined surface from the joint surface is 13 μm or more 33
μm or less.

In the semiconductor light emitting device described above, the first
A semiconductor substrate including a pn junction formed by the semiconductor layer and the second semiconductor layer has a mesa shape having an inclined surface formed by mesa etching. Thereby, when passing through the lens, good collimated light can be obtained as output light.

In particular, by setting the mesa depth of the inclined surface within the above numerical range with respect to the thickness of the first semiconductor layer, which is the depth of the pn junction, the inclined surface can be combined with the first main surface. Also functions as a light exit surface, and emits light diffusely reflected by a second principal surface or the like opposite to the first principal surface, which is a light exit surface, from the first principal surface and the inclined surface, thereby providing a sufficient output. Light quantity can be secured. Further, it is possible to obtain output light having a sufficiently uniform light output distribution within the light beam diameter.

In the manufacture of a semiconductor light emitting device having such a configuration, it is sufficient to perform mesa etching on a normal semiconductor light emitting device. Differently, the manufacturing process is not complicated. Therefore, the light output conditions can be optimized, and at the same time, the manufacturing efficiency can be improved, and the cost of the semiconductor light emitting device can be reduced.

Further, the ratio of the mesa depth of the inclined surface to the thickness of the first semiconductor layer in the semiconductor substrate is further in the range of 7/3 to 10/3. Alternatively, the mesa depth of the inclined surface from the first main surface of the semiconductor substrate is 2
It is characterized in that the mesa depth of the inclined surface from the joint surface is 16 μm or more and 28 μm or less. As a result, it is possible to achieve both satisfactory securing of a sufficient amount of output light and improvement of uniformity in the light output distribution, particularly well.

Here, it is preferable that the first main surface and the inclined surface are roughened so that the light emission efficiency from the inside of the semiconductor substrate is higher than that of a substantially flat surface.

Further, it is preferable that the second principal surface is roughened so that the reflection efficiency of light from inside the semiconductor substrate is higher than that of a substantially flat surface.

Thus, the first main surface and the inclined surface, and the second
By performing roughening (roughening) on the main surface under predetermined conditions, the utilization efficiency of light emitted in the semiconductor substrate can be improved. In the rough surface treatment on the first principal surface and the inclined surface, and the rough surface treatment on the second principal surface, each of them is improved so that the above-described improvement in light emission efficiency and improvement in reflection efficiency are realized. It is preferable to set the conditions for the rough surface treatment.

Further, the semiconductor light emitting device according to the present invention comprises:
(A) the semiconductor light emitting device described above, and (b) a package in which the semiconductor light emitting device is positioned and installed therein.
(C) a lens member facing the first main surface of the semiconductor light emitting device and fixed integrally to the package so that the optical axis of the semiconductor light emitting device coincides with the lens member.

By using such a lens member and a package, a semiconductor light emitting element and a lens can be reliably positioned, and a semiconductor light emitting device capable of obtaining output light under favorable light output conditions can be realized by a combination thereof. can do. Further, since the light emitted from the side face of the semiconductor light emitting element or the like is not provided with a reflection surface on the package side and the light emitted from the semiconductor light emitting element and incident on the lens member is used as the output light, In combination with the configuration of the semiconductor light emitting element of
When passing through a lens, output light with high parallelism can be obtained.

In the lens member, the curvature of the first surface on which the light emitted from the semiconductor light emitting element is incident is smaller than the curvature of the second surface on the opposite side of the first surface from which the light is emitted. Is also preferably formed by a small lens shape.

At this time, the light emitted from the semiconductor light emitting element is condensed by auxiliary light path conversion on the first surface of the lens member, and finally converted into collimated light on the second surface. The light path is converted and output. This allows
The utilization efficiency of light from the semiconductor light emitting element is improved, and it is possible to reliably convert the light into collimated light.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a semiconductor light emitting device and a semiconductor light emitting device using the same according to the present invention will be described below in detail with reference to the drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description. Also, the dimensional ratios in the drawings do not always match those described.

FIG. 1 is a side sectional view showing a configuration of an embodiment of a semiconductor light emitting device using a semiconductor light emitting element according to the present invention. In FIG. 1, the cross-sectional structure is shown by a vertical cross-section including the optical axis of the output light from the semiconductor light emitting device (the central axis of the semiconductor light emitting element and the semiconductor light emitting device).

First, the overall configuration of the semiconductor light emitting device will be described. The semiconductor light-emitting device according to the present embodiment includes a light-emitting diode (LED) 1 that is a semiconductor light-emitting element, a package 5 in which the light-emitting diode 1 is housed, and light emitted from the light-emitting diode 1 passing therethrough to output light. And a lens member 6 that is output to the outside.

The light emitting diode 1 has a p-type conductivity (first type).
A p-type semiconductor layer (first semiconductor layer) 11 of a conductivity type;
An n-type semiconductor layer whose conductivity type is n-type (second conductivity type) (second
And a semiconductor substrate 12 having a substantially horizontal cross-sectional shape. Here, of the upper and lower main surfaces of the semiconductor substrate 10, the surface on the p-type semiconductor layer 11 side (the upper surface in FIG. 1) is referred to as the first main surface 13,
A surface (a bottom surface in FIG. 1) on the second side opposite to the first main surface 13 is referred to as a second main surface 14.

On the first main surface 13 of the semiconductor substrate 10, p
A first electrode (anode electrode) 21 which is a metal electrode joined to the mold semiconductor layer 11 is formed. Further, on the second main surface 14, a second electrode (cathode electrode) 22, which is a metal electrode joined to the n-type semiconductor layer 12, is formed. As a result, the present semiconductor light-emitting device has the p-type semiconductor layer 1
1 and pn formed by the junction surface of n-type semiconductor layer 12
The light emitting diode 1 has a junction.

Here, in the semiconductor substrate 10 of the present light emitting diode 1, a p-type semiconductor layer 11 and an n-type semiconductor layer 12 are stacked such that the pn junction is near the first main surface 13. The first main surface 13 on the upper surface facing the p-type semiconductor layer 11 is an emission surface from which light emitted in the semiconductor substrate 10 is emitted. Note that the p-type semiconductor layer 11 and the n-type semiconductor layer 12 may each have a configuration in which a plurality of p-type semiconductor layers and n-type semiconductor layers are stacked.

The semiconductor substrate 10, the first electrode 21, and the second
The above-described light-emitting diode 1 including the electrodes 22 is stored and installed inside the package 5 having a substantially cylindrical horizontal cross section. The package 5 in the present embodiment includes:
It has a pedestal part 51 constituting the bottom surface and a cylindrical side part 52 constituting the side surface.

Above the side portion 52, a lens member 6 which is a light transmitting window made of a material that transmits light from the light emitting diode 1 is provided so as to cover a circular opening at the upper end of the side portion 52. . The lens member 6 functions as a lens that allows light emitted in the semiconductor substrate 10 and emitted from the light emitting diode 1 to pass therethrough and output to the outside as output light having predetermined light output conditions. The lens member 6 forms the upper surface of the package 5 and is integrally fixed to the side portion 52, and the side portion 52 and the lens member 6 serve as a lid of the package 5 with respect to the base 51. I have.

The base 51 has a substantially flat upper surface, and serves as a mounting table on which the light emitting diode 1 is mounted. The light emitting diode 1 has its semiconductor substrate 10
Of the second main surface 14 and the second electrode 22 as the base 51 side,
It is positioned and installed with respect to the base 51. Also, the second
The gap between the surface of the main surface 14 excluding the portion where the second electrode 22 is formed and the upper surface of the base 51 is filled with Ag paste or the like. A pin (not shown) for supplying a necessary voltage to the light emitting diode 1 or reading a signal is provided on the lower surface side of the base 51 as necessary.

With the above configuration, the side 52 and the lens member 6 are fixed to the base 51 to which the light emitting diode 1 is fixed.
By mounting the lid made of from above, the semiconductor light emitting device of FIG. 1 in which the light emitting diode 1 is positioned and installed inside the package 5 including the lens member 6 is obtained.

At this time, in the light emitting diode 1 housed inside the package 5, the first main surface 13 of the semiconductor substrate 10, which is the light emitting surface, is located at a position facing the lens member 6 on the upper surface of the package 5. . Also, the lens member 6
Are positioned with respect to the package 5 (side portion 52) such that the optical axis of the lens coincides with the optical axis of the light emitting diode 1. P-type semiconductor layer 11 and n-type semiconductor layer 12
The light emitted from the semiconductor substrate 10 of the light emitting diode 1 by the pn junction and emitted from the first main surface 13 passes through the lens member 6 so that the light output directions are substantially parallel within the light beam diameter. The light is converted into collimated light and output to the outside as output light.

Next, the structure of the light emitting diode 1 which is a semiconductor light emitting element will be described more specifically with reference to FIGS. FIG. 2 is a plan view of the light emitting diode 1 used in the semiconductor light emitting device shown in FIG. 1, and FIG. 2A is a top view of the semiconductor substrate 10 viewed from the first main surface 13 side. FIG. 2B is a bottom view as viewed from the second main surface 14 side.

As shown in FIGS. 2A and 2B, the light-emitting diode 1 has a semiconductor substrate 10 formed in a substantially square chip shape with a horizontal cross section. With respect to this chip shape, the first electrode 21 provided on the first main surface 13 so as to be joined to the p-type semiconductor layer 11 is substantially the same as the first main surface 13 as shown in FIG. A circular shape having a predetermined radius is formed at the center position. Further, the second electrode 22 provided on the second main surface 14 so as to be bonded to the n-type semiconductor layer 12 includes:
As shown in FIG. 2B, the entire second main surface 14 is formed in a honeycomb shape.

An inclined surface 15 having a predetermined width w1 and extending from the first main surface 13 to the side surface is formed at the outer edge of the first main surface 13 of the semiconductor substrate 10. The inclined surface 15 is formed by mesa etching, and has a substantially circular vertical cross-sectional shape as shown in FIG. Thus, the light emitting diode 1 is a mesa light emitting diode.

The inclined surface 15 formed by the mesa etching is
The semiconductor substrate 10 is formed so as to satisfy a predetermined condition with respect to the depth of the pn junction. That is, as shown in FIG. 1, the first main surface 13 which is the thickness of the p-type semiconductor layer 11 is formed.
Assuming that the depth of the pn junction from the first surface d1 and the mesa depth of the inclined surface 15 from the first main surface 13 is d2, the mesa depth d2 is pn
It is set to be larger than the junction depth d1 (d2> d1). At this time, the p-type semiconductor layer 11 and the n-type semiconductor layer 1
2 is exposed on the inclined surface 15. This inclined surface 15 also functions as a light emitting surface, like the first main surface 13.

Further, in the present light emitting diode 1,
As described later, in order to optimize the light output condition, p
The inclined surface 15 is formed such that the ratio of the mesa depth (the depth of the inclined surface 15) d2 to the depth of the n-junction (the thickness of the p-type semiconductor layer 11) d1 satisfies the condition 2 ≦ d2 / d1 ≦ 4. Is formed.

Alternatively, the mesa depth d2 is
To satisfy the condition of 25 μm ≦ d2 ≦ 45 μm or the condition of the mesa depth from the junction surface (pn junction) of the p-type semiconductor layer 11 and the n-type semiconductor layer 12 so as to satisfy 13 μm ≦ d2−d1 ≦ 33 μm. In addition, an inclined surface 15 is formed.

In the present embodiment, the first main surface 13 and the inclined surface 15, which are light emission surfaces, are formed as rough surfaces (rough surfaces) subjected to a roughening process (roughening). The rough surface treatment on the first main surface 13 and the inclined surface 15 is for increasing the emission efficiency of light emitted in the semiconductor substrate 10 as compared with a substantially flat surface.

The second main surface 14 is also subjected to a roughening process (roughening). The rough surface treatment on the second main surface 14 is for increasing the reflection efficiency of light emitted in the semiconductor substrate 10 as compared with a substantially flat surface.

As described above, the first main surface 13 and the inclined surface 15
By subjecting the second main surface 14 and the second main surface 14 to roughening under predetermined conditions, the utilization efficiency of light emitted in the semiconductor substrate 10 can be improved. The first main surface 13 and the inclined surface 15 are roughened, and the second
In the rough surface treatment for the main surface 14, the conditions of the respective rough surface treatments, such as the type of the roughening treatment liquid used, such that the above-described improvement in the light emission efficiency and the improvement in the reflection efficiency are realized. (See Japanese Patent No. 2907170).

The effect of the light emitting diode 1 according to the present embodiment will be described. In the above-described light-emitting diode 1, the pn by the p-type semiconductor layer 11 and the n-type semiconductor layer 12
The semiconductor substrate 10 including the junction has a mesa shape having an inclined surface 15 formed by mesa etching.
Thereby, the light beam diameter of the output light from the light emitting diode 1 itself can be reduced.

Here, in the semiconductor light emitting device including the light emitting diode 1, it is preferable that the light emitting diode 1 is close to a point light source in order to obtain good collimated light as output light when passing through a lens. In order to use a light emitting diode as a point light source, for example, there is a configuration in which a current confinement mechanism is provided in the chip. However, such a configuration complicates the manufacturing process, lowers the manufacturing efficiency and increases the cost. In addition, there are many problems such as insufficient output light quantity and low reliability for long-term use.

Further, it is also possible to reduce the chip size of the light emitting diode itself so as to approach a point light source. However, in this case as well, a decrease in the amount of output light poses a problem as described above. Further, according to the result of the study by the present inventor, in a normal chip shape, the light output distribution within the light beam diameter is not uniform due to the influence of light emitted from the side surface of the chip.

Further, a configuration in which the emission surface of the chip is formed in a dome shape is possible, but the etching process of the chip in a dome shape complicates the manufacturing process.

On the other hand, according to the above configuration, the inclined surface 15 is formed by mesa etching on the outer edge of the first main surface 13 which is the light emission surface of the semiconductor substrate 10 so as to satisfy a predetermined condition. The first main surface 13 and the inclined surface 15 function as light emission surfaces, and the light diffusely reflected by the second main surface 14 and the like is emitted from the first main surface 13 and the inclined surface 15 to provide a sufficient output. Light quantity can be secured. At the same time, good collimated light can be obtained as output light when passing through the lens.

Further, as a condition for the mesa shape by the inclined surface 15, the ratio d 2 / d 1 of the mesa depth d 2 to the depth d 1 of the pn junction is set to 2 or more and 4 or less, or from the first main surface 13. Mesa depth d2 25 μm or more 4
5 μm or less, or mesa depth d2-d1 from pn junction
Is set to 13 μm or more and 33 μm or less, the output light that has passed through the lens is a collimated light having a high degree of parallelism and an output light having a sufficiently uniform light output distribution within the light beam diameter. It is possible to obtain.

Regarding the condition for the mesa shape, it is preferable that d2 / d1 be 7/3 or more and 10/3 or less. Alternatively, d2 should be 28 μm or more and 40 μm.
m or less, or d2−d1 is preferably 16 μm or more and 28 μm or less. As a result, it is possible to achieve both satisfactory securing of a sufficient amount of output light and improvement of uniformity in the light output distribution, particularly well.

The light emitting diode 1 having such a configuration
In the manufacture of the LED, it is only necessary to perform the mesa etching on the ordinary light emitting diode, so that the manufacturing process does not become complicated unlike the configuration in which the emission surface itself of the LED chip has a dome shape. Therefore, the light output condition can be optimized, and at the same time, the manufacturing efficiency can be improved and the cost of the light emitting diode can be reduced.

The above-described effect of the present light-emitting diode 1 will be described using a specific embodiment in which the mesa depth d2 is changed in the light-emitting diode 1 having the configuration shown in FIGS. In the following examples, the chip size of the semiconductor substrate 10 was 280 μm × 280 μm square, the total thickness was 175 μm, and the layer thickness d1 of the p-type semiconductor layer 11, which was the depth of the pn junction, was 12 μm.

The first electrode 21 on the first main surface 13 and the second electrode 22 on the second main surface 14 are both Au electrodes. The diameter of the first electrode 21 is set to φ120.
μm. Further, the inclined surface 15 formed at the outer edge of the first main surface 13 of the semiconductor substrate 10 has a width w1.
Was about 25 μm. At this time, the first excluding the inclined surface 15
The size of the main surface 13 is about 230 μm × 230 μm.

Under the above-described configuration conditions, the mesa depth d2 of the inclined surface 15 and the ratio d2 / d1 are expressed by (A) d2 = 0 μm.
m, d2 / d1 = 0, (B) d2 = 20 μm, d2 / d
1 = 5/3, (C) d2 = 30 μm, d2 / d1 = 5 /
2. (D) The light emitting diodes 1 were prepared by changing d2 = 50 μm and d2 / d1 = 25/6, respectively.

The light output distributions obtained by the light emitting diode 1 formed by changing the mesa depth d2 in this manner are shown in graphs A to D of FIG. 3, respectively. These graphs A ~
In D, the light emitted from the light emitting diode 1 is not measured as the collimated light through the lens member 6 of the semiconductor light emitting device as the collimated light, but the light emitting angle (horizontal axis) in the state of the light emitting diode 1 alone. Output light with respect to (vertical axis)
Is measured and shown.

Specifically, the light emitting diodes 1 to 300
In addition to installing a photodiode for measuring the amount of light at a position of mm, and measuring the amount of emitted light at each light emission angle while changing the angle of the light emitting diode 1 with respect to this photodiode, a light emission distribution was created. The distribution of the light emission angle (light emission distribution) corresponds to the light incident on the lens member 6 and is reflected in the distribution of the light output position (light output distribution) when the light is transmitted through the lens member 6 to be collimated light. Things. Note that the angle at which the photodiode is installed on the optical axis of the light emitting diode 1 is defined as a light emission angle of 0 °.

According to the graph shown in FIG. 3, d2 = 0 μm
In graph A (dashed line) in which the mesa etching was not performed on the semiconductor substrate 10, the light emission amount decreases near 0 °, and the light emission amount becomes square at both ends exceeding ± 30 ° in the light emission angle. The light emission distribution protrudes in the direction. That is, uniformity of the light emission distribution within the light beam diameter is not obtained. In graph B (dashed-dotted line) of a mesa shape with d2 = 20 μm, the projection of the emitted light quantity is not sufficiently improved, especially at a light emission angle of −30 ° or less.

On the other hand, in a graph C (solid line) having a mesa shape with d2 = 30 μm, a decrease in the amount of emitted light near 0 ° is suppressed, and a sufficient amount of emitted light is obtained. , The protrusion of the emitted light amount at both ends exceeding ± 30 ° is reduced, and a sufficiently uniform light emission distribution (light output distribution) within the light beam diameter is obtained. Also, as for the entire emitted light amount, the light amount almost equal to that of a normal light emitting diode which is not a mesa type (graph A) is obtained.

Further, in the graph D (dotted line) having a mesa shape of d2 = 50 μm, although the uniformity of the light emission distribution within the light beam diameter is improved, the entire light emission amount is reduced. I'm done. Graph E (two-dot chain line) is an example in which d2 = 30 μm and almost the same configuration conditions as those in graph C, with the other conditions being slightly changed. Such a light emission distribution is obtained.

In addition to this result, the mesa depth d2 of the inclined surface 15 and the ratio d2 / d1 are further expressed as (F) d2 = 28
μm, d2 / d1 = 7/3, (G) d2 = 32 μm, d
2 / d1 = 8/3, (H) d2 = 40 μm, d2 / d1
= 10/3, and light-emitting diodes 1 were prepared.

The light output distributions obtained by the light emitting diode 1 formed by changing the mesa depth d2 in this manner are shown in graphs F to H of FIG. 4, respectively. FIG. 4 also shows the graphs A and C shown in FIG. 3 for comparison. In each of these graphs F to H,
Similarly to the graph C of d2 = 30 μm, a decrease in the amount of emitted light near 0 ° is suppressed, and a sufficient amount of emitted light is obtained, and at the same time, the projected amount of emitted light at both ends exceeding ± 30 ° is obtained. Is reduced, and a sufficiently uniform light emission distribution within the light beam diameter is obtained.

According to the above result, the mesa depth d2 is pn
If it is smaller than the junction depth d1, the effect of improving the uniformity in the light output distribution due to the mesa shape cannot be sufficiently obtained. On the other hand, if the mesa depth d2 is too large, the slope 1
The output light amount is reduced due to the shape of No. 5, the area of the pn junction being reduced, and the like.

In consideration of these, the mesa depth d2 from the first main surface 13 is 25 μm or more and 45 μm or less (the mesa depth d2−d1 from the pn junction is 13 μm or more and 33 μm or less), or a pn junction of d1 = 12 μm. In terms of the ratio to the depth, the ratio d2 / d1 is set to 2 or more and 4 or less, so that the output light when passing through the lens is a collimated light having high parallelism and within the light beam diameter. It can be seen that output light having a sufficiently uniform light output distribution can be obtained.

Further, the mesa depth d2 from the first main surface 13 is set to 28 μm or more and 40 μm or less (the mesa depth d2-d1 from the pn junction is set to 16 μm or more and 28 μm or less, the ratio d2
/ D1 is preferably 7/3 or more and 10/3 or less), and particularly, the mesa depth d2 is 30 μm (mesa depth d2-d).
1 is preferably 18 μm and the ratio d2 / d1 is preferably 5/2).

When the mesa depth d2 of the inclined surface 15 is increased, the uniformity of the light output distribution is improved as described above, while the output light amount is reduced. On the other hand, by setting the mesa depth d2 with respect to the depth d1 of the pn junction within a numerical range that satisfies the above conditions, it is possible to secure a sufficient amount of emitted light and improve the uniformity of the light output distribution. Good compatibility can be achieved. It is preferable that the value of the mesa depth d2 be set in consideration of the required output light quantity and light output distribution in each semiconductor light emitting element.

FIGS. 5 and 6 show examples of the distribution of the light output position in the semiconductor light emitting device corresponding to the distribution of the light emission angle of the light emitting diode 1 shown in FIGS. When the light emitting diode 1 is installed in the package 5 shown in FIG. 1, the light emitted from the light emitting diode 1 passes through the lens member 6 to be collimated light, which is output to the outside as output light. In the graphs shown in FIGS. 5 and 6, a one-dimensional image sensor for measuring the amount of light is installed at a position 5 mm from the lens member 6 to measure the light output distribution.
In the configuration of the above-described embodiment, light having a light emission angle in a range of about ± 30 ° is output as output light via the lens member 6.

In the graph of FIG. 5 in the case where the ordinary light emitting diode 1 having no mesa-shaped shape is used, the output light quantity at both ends of the light output distribution is similar to the graph A of the light emission distribution shown in FIG. Are protruding. On the other hand, in the graph of FIG. 6 in the case where the light emitting diode 1 having the mesa shape is used, a substantially uniform light output distribution is obtained within the light beam diameter.

As for the entire structure of the semiconductor light emitting device including the light emitting diode 1, as shown in FIG. 1, by using the package 5 to which the lens member 6 is fixed, the light emitting diode 1 and the lens can be securely connected. A semiconductor light emitting device that can obtain output light under favorable light output conditions is realized by performing alignment and combining them.

Further, a cup-shaped or other reflecting surface is not provided for light emitted from the side surface of the light emitting diode 1 or the like, and the upper surface of the base 51 is made substantially flat. Thus, in combination with the configuration of the mesa-type light emitting diode 1, it is possible to obtain output light with high parallelism when passing through a lens while securing a sufficient output light amount.

The lens member 6 integrally fixed to the package 5 has a lens inner surface (first surface) 61 facing the light emitting diode 1 and receiving light emitted from the light emitting diode 1. And a lens outer surface (second surface) 62 which is a surface from which light is emitted on the opposite side of the lens inner surface 61 is formed to have a predetermined lens shape (surface shape). The surface shape of each of the lens surfaces 61 and 62 is preferably a lens shape in which the curvature of the lens inner surface 61 is smaller than the curvature of the lens outer surface 62.

The function of condensing and collimating the light emitted from the light emitting diode 1 is provided on both sides 61 of the lens member 6.
62, the light from the light emitting diode 1 can be converted to collimated light. However,
Increasing the curvature of the lens inner surface 61 facing the light emitting diode 1 inside the package 5 may cause a problem in the configuration of the semiconductor light emitting device.

On the other hand, the lens outer surface 6
2, the light emitted from the light emitting diode 1 is condensed by auxiliary light path conversion on the lens inner surface 61 having a small curvature, and further has a large curvature. The optical path is finally converted into collimated light by the lens outer surface 62 and output. Thereby, the use efficiency of light from the light emitting diode 1 is improved, and it is possible to reliably convert the light into collimated light.

The lens inner surface 61 and the lens outer surface 62
As to the specific lens shape, a spherical lens or an aspherical lens can be used as necessary. For example, a configuration is possible in which the lens inner surface 61 is a spherical lens having a small curvature to collect light, and the lens outer surface is an aspheric lens having a large curvature to collimate the light. Also,
The lens inner surface 61 may be formed in a planar shape with a curvature of 0.

An example of the method for manufacturing the light emitting diode of the above embodiment will be schematically described. FIG.
FIG. 8 is a process chart schematically showing an example of a method for manufacturing the light emitting diode 1 shown in FIG. Here, FIG.
(A)-(c) have shown each process which produces the basic structure of the light emitting diode 1 provided with the semiconductor base 10, the 1st electrode 21, and the 2nd electrode 22. FIG. In addition, FIG.
(C) shows each step of forming the inclined surface 15 by mesa etching to form the mesa light emitting diode 1.

FIGS. 7 and 8 show each process for one light emitting diode. However, in the actual process, FIGS. 7 (a) to 7 (c) and FIG.
In each of the steps (a) to (c), after forming a plurality of elements on the semiconductor wafer at one time, the light emitting diode 1 is obtained by separating each element.

First, a semiconductor substrate (semiconductor wafer) 10 on which a p-type semiconductor layer 11 and an n-type semiconductor layer 12 are laminated is prepared. As a semiconductor wafer, for example, AlGaAs,
A compound semiconductor substrate such as GaAs is used. Then, electrode material layers 31 and 32 made of a predetermined metal (for example, Au) are formed on the entire upper and lower main surfaces 13 and 14 of the semiconductor substrate 10 (FIG. 7A).

Next, the second main surface 14 on the n-type semiconductor layer 12 side
, Such as forming the second electrode 22 (FIG. 7).
(B)). Electrode material layer 32 formed on second main surface 14
To a second electrode 2 serving as a cathode electrode
Form 2 Then, the second main surface 14 excluding the portion where the second electrode 22 is formed is subjected to a surface roughening process using a predetermined roughening solution to increase the light reflection efficiency.

Similarly, the first main surface 1 on the p-type semiconductor layer 11 side
3 is processed such as formation of the first electrode 21 (FIG. 7).
(C)). Electrode material layer 31 formed on first main surface 13
To a first electrode 2 serving as an anode electrode
Form one. Then, the first main surface 13 excluding the portion where the first electrode 21 is formed is subjected to a roughening process for increasing light emission efficiency using a predetermined roughening solution.
Thus, each step of creating the basic structure of the light emitting diode 1 is completed.

Subsequently, the light emitting diode 1 is subjected to mesa etching to form an inclined surface 15. First, a circular second electrode 21 is formed on the first main surface 13 serving as a light emission surface.
And a resist 40 is applied so as to leave the outer edge (see FIG. 2A) of the first main surface 13 forming the inclined surface 15 (FIG. 8A).

After the resist pattern is formed by the resist 40, mesa etching is performed using a predetermined etching solution, and a mesa depth d2 set in advance with respect to the pn junction depth d1 so as to satisfy the above-described conditions. Thus, the inclined surface 15 is formed (FIG. 8B). Then, the formed inclined surface 15 is subjected to a roughening process for increasing the light emission efficiency, similarly to the first main surface 13, using a predetermined roughening treatment liquid (FIG. 8C). ). Thus, each step of fabricating the mesa light emitting diode 1 is completed. Then, the light emitting diode 1 shown in FIG. 1 is obtained by separating the produced elements.

The semiconductor light emitting device and the semiconductor light emitting device using the same according to the present invention are not limited to the above-described embodiments and examples, and various modifications are possible. For example, with respect to the rough surface treatment on the first principal surface, the inclined surface, and the second principal surface, a rough surface treatment is performed on the first principal surface and the inclined surface. Only the rough surface may be used. Further, the specific configuration conditions such as the size of the semiconductor light emitting element are not limited to those in the above-described embodiment, but may be set to suitable configuration conditions according to required light output conditions.

[0080]

As described above in detail, the semiconductor light emitting device and the semiconductor light emitting device using the same according to the present invention are as follows.
The following effects are obtained. That is, the semiconductor substrate including the pn junction formed by the first semiconductor layer and the second semiconductor layer is subjected to the condition that the ratio of the mesa depth to the depth of the pn junction is 2 or more and 4 or less, or the mesa depth from the first main surface. Is 25 μm or more and 45 μm or less, or the mesa depth from the pn junction is 13 μm
According to the mesa-shaped semiconductor light emitting device having the inclined surface formed so as to satisfy the condition of not less than m and not more than 33 μm, the light beam diameter of the light emitted from the semiconductor light emitting device itself was small and passed through the lens. Sometimes, a semiconductor light emitting element and a semiconductor light emitting device are provided, in which collimated light having high parallelism and output light having a sufficiently uniform light output distribution within the light beam diameter can be obtained and the manufacturing efficiency thereof is improved. Is realized.

Such a semiconductor light emitting device can be applied to an optical sensor such as a transmission optical encoder which is an angle sensor. In particular, output light under suitable light output conditions is obtained, and at the same time, the production efficiency is improved, so that a sufficient number of semiconductor light emitting devices can be supplied at low cost.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a configuration of an embodiment of a semiconductor light emitting device using a light emitting diode.

FIGS. 2A and 2B are a top view and a bottom view of a light emitting diode used in the semiconductor light emitting device shown in FIG.

FIG. 3 is a graph comparing light output distributions obtained by light emitting diodes created by changing the mesa depth.

FIG. 4 is a graph comparing light output distributions obtained by light emitting diodes created by changing the mesa depth.

FIG. 5 is a graph showing an example of a light output distribution in a semiconductor light emitting device using a normal light emitting diode.

FIG. 6 is a graph showing an example of a light output distribution in the semiconductor light emitting device shown in FIG.

FIG. 7 is a process chart schematically showing an example of a method for manufacturing the light-emitting diode shown in FIG.

FIG. 8 is a process chart schematically showing an example of a method for manufacturing the light-emitting diode shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Light-emitting diode, 10 ... Semiconductor base, 11 ... P-type semiconductor layer (1st semiconductor layer), 12 ... N-type semiconductor layer (2nd semiconductor layer), 13 ... 1st main surface, 14 ... 2nd main surface, Reference numeral 15: inclined surface, 21: first electrode (anode electrode), 22: second electrode (cathode electrode), 5: package, 51: base, 5
2 ... side part, 6 ... lens member, 61 ... lens inner surface (first surface), 62 ... lens outer surface (second surface).

Claims (8)

[Claims] A first semiconductor layer having a first conductivity type and a second semiconductor layer having a second conductivity type are stacked;
A semiconductor substrate in which a pn junction is formed by a bonding surface between the semiconductor layer and the second semiconductor layer; and a first surface from which light is emitted from inside the semiconductor substrate on a surface of the semiconductor substrate on the first semiconductor layer side. A first electrode formed on a main surface; and a first electrode formed on a surface of the semiconductor substrate on the second semiconductor layer side.
A second electrode formed on a second main surface opposite to the main surface;
The semiconductor substrate has a mesa shape in which an inclined surface extending from the first main surface to a side surface is formed at an outer edge portion of the first main surface, and the inclined surface with respect to a layer thickness of the first semiconductor layer Wherein the ratio of the mesa depth is 2 or more and 4 or less. 2. The semiconductor device according to claim 1, wherein a ratio of a mesa depth of the inclined surface to a thickness of the first semiconductor layer in the semiconductor substrate is 7/3 or more and 10/3 or less. Semiconductor light emitting device. 3. A first semiconductor layer having a first conductivity type and a second semiconductor layer having a second conductivity type are stacked, and
A semiconductor substrate in which a pn junction is formed by a bonding surface between the semiconductor layer and the second semiconductor layer; and a first surface on the first semiconductor layer side of the semiconductor substrate, from which light from the semiconductor substrate is emitted. A first electrode formed on a main surface; and a first electrode formed on a surface of the semiconductor substrate on the second semiconductor layer side.
A second electrode formed on a second main surface opposite to the main surface;
The semiconductor substrate has a mesa shape in which an inclined surface extending from the first main surface to a side surface is formed at an outer edge portion of the first main surface, and a mesa of the inclined surface from the first main surface is formed. A semiconductor light emitting device, wherein a depth is 25 μm or more and 45 μm or less, or a mesa depth of the inclined surface from the bonding surface is 13 μm or more and 33 μm or less. 4. The mesa depth of the inclined surface from the first main surface in the semiconductor substrate is 28 μm or more and 40 μm or less, or the mesa depth of the inclined surface from the bonding surface is 16 μm or more and 28 μm or less. The semiconductor light emitting device according to claim 3, wherein: 5. The semiconductor device according to claim 1, wherein the first main surface and the inclined surface are roughened so that light emission efficiency from the inside of the semiconductor substrate is higher than a substantially flat surface. Item 5. The semiconductor light emitting device according to any one of items 1 to 4. 6. The semiconductor device according to claim 1, wherein the second main surface is roughened so that the reflection efficiency of light from inside the semiconductor base is higher than a substantially flat surface. The semiconductor light emitting device according to any one of the above. 7. The semiconductor light emitting device according to claim 1, a package in which the semiconductor light emitting device is positioned and installed therein, and the semiconductor light emitting device according to claim 1 And a lens member integrally fixed to the package so that an optical axis of the semiconductor light emitting element coincides with the semiconductor light emitting element. 8. The lens member according to claim 1, wherein a curvature of a first surface on which light emitted from the semiconductor light emitting element is incident is a second surface on which light is emitted on a side opposite to the first surface. 8. The semiconductor light emitting device according to claim 7, wherein the semiconductor light emitting device is formed by a lens shape smaller than a curvature of the semiconductor light emitting device.