JPH05243610A - Semiconductor light emitting device - Google Patents

Abstract

PURPOSE:To form an end face luminous type light emitting device by covering an insular light emitting device excepting one side with an electrode material. CONSTITUTION:This semiconductor element is provided with an insular part I consisting of at least two layer single crystal semiconductor layers having different conduction types on a single crystal semiconductor substrate 1 while being provided with a transparent protective layer 6 extending from the side on the semiconductor substrate of this insular part I while the upper part and the side of this insular part I are covered with an electrode 7 and leaving one side of the insular part I while providing the insular part I so that one side of the insular part I uncovered with the electrode 7 may have the <1-10> direction while the other side may not come between the <010> direction and the <-100> direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor light emitting device,
For example, the present invention relates to a semiconductor light emitting element used as a light source of a photosensitive drum for a page printer or a light emitting element of an optical communication device.

[0002]

2. Description of the Related Art In explaining the crystal plane direction, bar 1 is indicated by -1.

In recent years, semiconductor light emitting devices have been actively studied with the progress of compound semiconductor crystal techniques such as MOCVD (metal organic chemical vapor deposition) and MBE (molecular beam epitaxial).

A conventional semiconductor light emitting device will be described with reference to FIG. FIG. 5 is a cross-sectional view of a conventional semiconductor light emitting device, 21 is a single crystal substrate made of silicon (Si) containing impurities for one conductivity type semiconductor, 22 is a buffer layer made of gallium arsenide (GaAs), etc. , 23 is a first semiconductor layer made of aluminum gallium arsenide (AlGaAs) having the same conductivity type as the silicon substrate 21, and 24 is aluminum gallium arsenide having a conductivity type opposite to that of the first semiconductor layer 23. A second semiconductor layer made of, for example, 25 is an ohmic contact layer made of gallium arsenide or the like containing a large amount of impurities for the opposite conductivity type semiconductor so as to make ohmic contact with the upper electrode 27, and 26 is, for example, silicon nitride (SiN _x ) It is a protective layer consisting of. A contact hole 26a is formed in the protective layer 26 on the ohmic contact layer 25, and the upper electrode 27 is connected to the ohmic contact layer 25 through the contact hole 26a. Also, the silicon substrate 2
A lower electrode 28 for making ohmic contact with the silicon substrate 21 is provided on the back surface side of 1. In this semiconductor light emitting device, a semiconductor junction is formed between the first semiconductor layer 23 and the second semiconductor layer 24 to form a light emitting layer. In addition, the buffer layer 22, the first semiconductor layer 23, the second semiconductor layer 24, and the ohmic contact layer 25 are formed in an island shape to form an island portion I.

In the thus configured semiconductor light emitting device, if the first semiconductor layer 23 is, for example, n-type and the second semiconductor layer 24 is, for example, p-type, the upper electrode 26 is positive and the lower electrode 27 is When a voltage is applied in the forward bias direction as negative, minority carriers are injected from the n-type first semiconductor layer 23 into the p-type second semiconductor layer 24, and the second semiconductor layer 24
At the interface between the semiconductor junction and the second semiconductor layer 24, which is the interface between the first semiconductor layer 23 and the first semiconductor layer 23, carriers recombine and emit light. The emitted light is used as the second semiconductor layer 24 and the protective layer 26.
It is taken out to the outside through.

However, in the above-described conventional semiconductor light emitting device, since the light emitted at the semiconductor junction is extracted in the direction in which the upper electrode 27 of the semiconductor substrate 21 is provided, such a semiconductor light emitting device is connected to an external circuit. In this case, the upper electrode 8 must be connected to the external circuit by the wire bonding method, and the connection with the external circuit is complicated and the reliability of the connection is low.

That is, in the face-down bonding method such as solder bump bonding or micro bump bonding, the semiconductor device as described above can be firmly fixed on the external circuit board simultaneously with the connection of the external circuit. Since the conventional semiconductor light emitting element extracts light to the portion where the upper electrode 8 is provided, the upper electrode 8 is connected to an external circuit on the supporting substrate by a face-down bonding method. When connected, the light is blocked by the external circuit board.

Further, in the conventional semiconductor light emitting device, since light is extracted from the upper electrode 27 side, the upper electrode 27 must be formed in the smallest possible area so as not to block the extraction of light, and as a result, the semiconductor junction is formed. There was a problem that the flow of current in the part was localized and the emission intensity was weak.

Further, in the conventional semiconductor light emitting device, as shown in FIG. 6, the side surfaces Ia and Ib of the island-shaped portion I have a <1-10> direction.
It is formed so as to face the <110> direction, or, as shown in FIG. 7, the side surfaces Ia and Ib of the island-shaped portion I are aligned with the <010> direction and <1>.
Although it was formed in a rectangular shape so as to face the <00> direction, if the side surfaces Ia and Ib of the island-shaped portion are formed so as to face the <1-10> direction and the <110> direction (see FIG. 6), <110 Although it has a forward mesa shape in the> direction, it has a reverse mesa shape in the <1-10> direction, and the side surfaces Ia and Ib of the island-shaped portion I are in the <010> direction and the <100> direction.
> If it is formed so as to face the direction (see FIG. 7), the mesa angle becomes 90 degrees in all directions, and in any case, it is difficult to cover the side surface of the island with the electrode member. It was

[0010]

The semiconductor light emitting device according to the present invention has been made in view of the above problems of the prior art, and is characterized in that it has a conductive type on a single crystal semiconductor substrate. Of at least two different single crystal semiconductor layers are provided, and a translucent insulating film is applied from the side surface of the island-shaped portion to the semiconductor substrate. In the semiconductor light-emitting device in which one side surface of the portion is covered with an electrode, one side surface of the island-shaped portion not covered with the electrode is the <1-10> direction, and the other side surface is from the <010> direction to the <-100> direction. The island-shaped portion is provided so as not to enter between the directions.

[0011]

With the above-described structure, all the side surfaces of the island-shaped portion other than the light extraction surface can be formed into a regular mesa shape. The side surface other than the side surface to be the surface can be surely covered with the electrode material, and the edge emitting type light emitting element can be obtained.

[0012]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

In explaining the crystal plane direction, bar 1 is indicated by -1.

FIG. 1 is a sectional view showing an embodiment of a semiconductor light emitting device according to the present invention, in which 1 is a single crystal semiconductor substrate and 2 is a single crystal semiconductor substrate.
Is a buffer layer, 3 is a first semiconductor layer having the same conductivity type as that of the single crystal semiconductor substrate 1, and 4 is a second semiconductor containing impurities of opposite conductivity type forming a semiconductor junction with the first semiconductor layer 3. Layer, 5 is an ohmic contact layer, 6 is a protective layer,
Reference numerals 7 and 8 are electrodes.

The single crystal semiconductor substrate 1 is, for example, (100)
It is composed of a single crystal silicon substrate cut off by 2 ° from the plane to the (011) plane and contains about 10 ¹⁹ donors / cm ^{3 of} antimony (Sb) or the like.

On the single crystal semiconductor substrate 1, one conductivity type is provided.
A buffer layer 2 containing impurities is formed. this
The buffer layer 2 is made of gallium arsenide (GaAs), etc.
Become. The buffer layer 2 is made of silicon (Si) or the like.
10 donors¹⁷Pieces / cm³Contains about two levels and grows in two stages
1 by the MOCVD method that appropriately adopts the thermal cycle method and the thermal cycle method.
It is formed to about 1.5 μm. That is, MOCVD
After heating the inside of the device at 900 to 1000 ° C once,
Lower to 0-450 ℃, TMGa gas, AsH ₃gas,
And SiH as an impurity element source for semiconductors_FourGas, etc.
A single crystal gallium arsenide layer is formed by the MOCVD method used.
In addition to increasing the length, raise the temperature to 600-650 ℃ and
Growing a arsenic / arsenic layer (two-step growth method), then 30
Thermal expansion by increasing and decreasing the temperature from 0 to 900 ° C (thermal cycle method)
The internal stress caused by the difference in tension coefficient
Due to the difference in lattice constant between the substrate 1 and the first semiconductor layer 3 described later.
Formed to reduce the misfit transition caused by
It

A first semiconductor layer 3 containing an impurity of one conductivity type is formed on the buffer layer 2. The first semiconductor layer 3 is made of aluminum gallium arsenide (A
1 _x Ga _1-x As) or the like. The first semiconductor layer 3 contains 10 ¹⁷ donors / c of silicon or the like.
Contains about m ³ . This first semiconductor layer 3 is TM
It is formed by the MOCVD method using Al gas, TMGa gas, AsH ₃ gas, and SiH ₄ gas which is an impurity element for semiconductor.

A second semiconductor layer 4 is formed on the first semiconductor layer 3. The second semiconductor layer 4 also, aluminum gallium arsenide _{(Al y Ga 1-y As} ) is formed in such. This second semiconductor layer 4, 10 an acceptor such as zinc as the opposite conductivity type semiconductor impurity (Zn) ¹⁷
Includes about 1 piece / cm ³ . This second semiconductor layer 4 is
MOC using TMAl gas, TMGa gas, AsH ₃ gas, and DMZn gas as a source of impurity elements for semiconductors
It is formed by the VD method. The first semiconductor layer 3 and the second semiconductor layer 4 described above form a semiconductor junction.

An ohmic contact layer 5 containing a large amount of impurities of opposite conductivity type is formed on the second semiconductor layer 4. The ohmic contact layer 5 is formed of, for example, gallium arsenide (GaAs) or the like, and contains a high concentration of a reverse conductivity type impurity such as zinc (Zn) for making ohmic contact with the electrode 7. A clad layer for enlarging the band gap and confining carriers may be provided between the second semiconductor layer 4 and the ohmic contact layer 5.

The semiconductor layers 2 to 5 described above form an island portion I. The semiconductor layers 2 to 5 are formed on the entire surface or a predetermined portion of the single crystal semiconductor substrate 1, but due to the difference in the coefficient of thermal expansion between the single crystal semiconductor substrate 1 and the semiconductor layers 2 to 5, the single crystal semiconductor is formed. The substrate 1 is warped or the semiconductor layers 2 to 5
In order to prevent the occurrence of cracks in the semiconductor layers, it is desirable to divide the semiconductor layers 2 to 5 into a plurality of small regions. On the other hand, the crystallinity of the semiconductor layer in the peripheral portion of the region selected for growing the semiconductor layers 2 to 5 is deteriorated due to the shape dependence, so that the selected region for growing the semiconductor crystal is the region where the light emitting element is formed. It is desirable that the area be sufficiently wider than that. That is, the semiconductor layers 2 to 5 are formed in a band shape wider than the region in which the light emitting elements are arranged in rows, and the sulfuric acid (H ₂ SO ₄ ), hydrogen peroxide (H
₂ O ₂ ) and water (H ₂ O) or the like, and is formed by etching or the like using an etching solution or the like.

FIG. 2B is a plan view of the island-shaped portion I, and is a view for explaining the orientation of the side surface of the island-shaped portion I (see FIG. 2B). The island-shaped portion I is composed of a side surface a which is a light extraction surface, side surfaces b and c continuous to the side surface a, a side surface d continuous to the side surface b, and a side surface e continuous to the side surface c, and has a shape in plan view. Is formed into a pentagon as a whole. In this island-shaped portion I, the side surface a serving as the light extraction surface is in the <1-10> direction, and the side surfaces b and c are <-1-10 respectively.
><110> direction, the side surface d is inclined from <-100> to <-1-10> direction, and the side surface e is inclined from <010> to <110> direction. That is, the side surfaces b, c, d, and e except the light extraction surface a are from <010> to <-10
It is formed so as not to fall within the range of 0>. in this case,
The angle θ formed by the side surface d and the side surface e may be set to 90 ° or less. In this way, the side faces b, c, d, and e from <010>
If it is formed so that it does not fall within the range of <-100>, side face b,
All of c, d, and e can be formed in a regular mesa shape.

FIG. 3B is a plan view of an island-shaped portion I having another shape, and is a view for explaining the orientation of the side surface of the island-shaped portion I. The island portion I has a side surface a ′ which is a light extraction surface, side surfaces b ′ and c ′ which are continuous with the side surface a ′,
It is composed of a side surface d'which is continuous with the side surface b ', and has a wedge shape as a whole in a plan view. In this island portion I, the side surface a'which is the light extraction surface is in the <1-10> direction, the side surfaces b'and c'are in the <-1-10><110> direction, and the side surface d is < It is installed in the direction inclined from -100> to <-1-10>. That is, the side surfaces b ′, c ′, d ′ except the light extraction surface a ′ are formed so as not to fall within the range of <010> to <-100>. In this case, the angle θ formed by the side surface c and the side surface d may be set to 45 ° or less. Even if the side surfaces b ′, c ′, d ′ are provided in this manner, the side surfaces b ′, c ′, d ′ can all be formed in a regular mesa shape.

The plurality of island-shaped portions I are provided in an array on the single crystal semiconductor substrate 1. When a plurality of island-shaped portions I are provided, they may be provided in the <110> direction.

As shown in FIG. 1, a transparent protective layer 6 is formed on the side surface of the island-shaped portion I. This protective layer 6
Is formed of, for example, a silicon nitride film (SiN _x ) or a silicon oxide film (SiO ₂ ), and is formed by, for example, a plasma CVD method using silane gas and ammonia gas (NH ₃ ) or laughing gas (N ₂ O). It is formed. .

An electrode 7 is formed on the surface of the island portion I excluding the light extraction surface. As described above, when the electrode 7 is formed on the surface of the island-shaped portion I excluding the light extraction surface, only the light extraction surface is optically exposed, and light is emitted from the side surface not covered with the electrode 7. The electrodes 7 and 8 are made of silver (Ag), silver / zinc (Ag / Zn), chromium / gold (Cr / Au), or the like, and are formed to a thickness of about 5000 Å by vapor deposition or sputtering. .. Further, when the electrode 8 on the other side is formed in the vicinity of the island-shaped portion I, the electrodes 7 and 8 are aligned with the one main surface side of the single crystal semiconductor substrate 1. Therefore, such a semiconductor light emitting device is provided on the external circuit substrate, Face down bonding becomes possible.

FIG. 4 shows a state of face-down bonding. In FIG. 4, 11 is an external circuit board,
The external circuit board 11 has a conductor pattern 1 for an external circuit.
2 and 13 are formed. The electrodes 7, 8 of the semiconductor light emitting device 10 are formed on the conductor patterns 12, 13 of the substrate 11.
Are opposed to each other and aligned, and are fixed by, for example, a micro bump bonding method. That is, the semiconductor light emitting device 1
In the vicinity of the electrodes 7 and 8 of 0 or in the vicinity of the conductor patterns 12 and 13 of the substrate 11, a liquid or sheet-shaped resin 14 that is cured by light or heat is applied to form electrodes 7 and 8 of the semiconductor light emitting element 10. Is accurately aligned with the conductor patterns 12 and 13 of the substrate 11, and the semiconductor light emitting device 10
The resin 14 is cured by light or heat while applying pressure to the semiconductor light emitting device 10 on the substrate 11.
Is fixed to form a semiconductor light emitting device. In this case, the semiconductor light emitting device 10 can be fixed and electrically connected at the same time. In FIG. 4, reference numeral 15 is a gold bump, which may be previously attached to the electrodes 7 and 8 or the conductor patterns 12 and 13.

Further, in the above embodiment, one side surface a of the island-shaped portion I not covered with the electrode 7 is in the <1-10> direction, and the other side surfaces b, c, d and e are in the <010> direction. Although it has been described that the island-shaped portions I are provided so as not to enter between the -100> directions, one side surface a of the island-shaped portions I not covered by the electrode 7 is in the <-110> direction, and Sides b, c, d,
It is obvious to those skilled in the art that the island portion I may be provided so that e does not enter between the <0-10> direction and the <100> direction, and the island portion I is provided in such a direction. It is also within the scope of the present invention.

[0028]

As described above, according to the semiconductor light emitting device of the present invention, the island-shaped portion composed of at least two single crystal semiconductor layers having different conductivity types is provided on the single crystal semiconductor substrate.
In the semiconductor light-emitting element, a translucent insulating film is deposited from the side surface of the island-shaped portion onto the semiconductor substrate, and the upper surface and the side surface of the island-shaped portion are covered with electrodes while leaving one side surface of the island-shaped portion,
The island-shaped portion is provided so that one side surface not covered with the electrode is in the <1-10> direction and the other side surface is not between the <010> direction and the <-100> direction. Therefore, all of the side surfaces of the island-shaped portion other than the side surface serving as the light extraction surface can be formed into a regular mesa shape, and thus, the side surface other than the side surface serving as the light extraction surface of the island-shaped portion can be formed of the electrode material. Thus, it is possible to form an edge emitting type light emitting element which is surely covered by the above method, and to connect to an external circuit by a face-down bonding method.

[0029]

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a semiconductor light emitting device according to the present invention.

2A is a diagram showing a plane orientation, and FIG. 2B is a diagram showing an arrangement direction of island-shaped portions of a semiconductor light emitting device according to the present invention.

FIG. 3A is a diagram showing a plane orientation, and FIG. 3B is a diagram showing another arrangement direction of the island-shaped portions of the semiconductor light emitting device according to the present invention.

FIG. 4 is a diagram showing a state in which the semiconductor light emitting device according to the present invention is mounted on an external circuit board by a face-down bonding method.

FIG. 5 is a cross-sectional view showing a conventional semiconductor light emitting device.

FIG. 6 is a diagram showing an arrangement direction of island-shaped portions in a conventional semiconductor light emitting device.

FIG. 7 is a diagram showing another arrangement direction of island-shaped portions in a conventional semiconductor light emitting device.

[Explanation of symbols]

1 ... Single crystal semiconductor substrate, 2 ... Buffer layer, 3 ...
..First semiconductor layer, 4 ... Second semiconductor layer, 5 ...
・ Ohmic contact layer, 7, 8 ... Electrode, I ...
-Islands.

Claims (2)

[Claims] 1. An island-shaped portion composed of at least two single crystal semiconductor layers having different conductivity types is provided on a single crystal semiconductor substrate,
In the semiconductor light emitting device, a transparent insulating film is deposited from the side surface of the island-shaped portion onto the semiconductor substrate, and the upper surface and the side surface of the island-shaped portion are covered with an electrode except for one side surface of the island-shaped portion. One side of the island that is not covered with is the <1-10> direction, and the other side is not located between the <010> direction and the <-100> direction. Semiconductor light emitting device. 2. The semiconductor light emitting device according to claim 1, wherein a plurality of the island-shaped portions are provided on the single crystal semiconductor substrate, and the plurality of island-shaped portions are arranged in the <110> direction.