JP2948967B2 - Semiconductor light emitting device - Google Patents

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,
In particular, the present invention relates to a semiconductor light emitting device in which at least two semiconductor layers having different conductivity types are formed in an island shape on a semiconductor substrate.

[0002]

2. Description of the Related Art In recent years, semiconductor light emitting devices have been actively studied with the progress of compound semiconductor crystal growth techniques such as MOCVD and MBE.

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, where 1 is a semiconductor substrate made of, for example, p-GaAs, etc.
2 is a buffer layer, 3 is a first semiconductor layer having the same conductivity type as the semiconductor substrate 1, 4 is a second semiconductor layer having a reverse conductivity type forming a semiconductor junction with the first semiconductor layer 3, and 5 is A third semiconductor layer in which the mixed crystal ratio of the semiconductor is changed to increase the band gap, 6 is an ohmic contact layer containing a large amount of impurities of the opposite conductivity type for making ohmic contact with the upper electrode 8, and 7 is, for example, silicon nitride. (SiNx)
And an insulating layer composed of A small hole 7a is formed in the insulating layer 7 on the ohmic contact layer 6, and the ohmic contact layer 6 is connected to the upper electrode 8 through the small hole 7a. A lower electrode 9 for making ohmic contact with the semiconductor substrate 1 is provided on the back surface side of the semiconductor substrate 1.

The operation of the semiconductor light emitting device thus configured will be described. When a voltage is applied in the forward bias direction with the upper electrode 8 being positive and the lower electrode 9 being negative, the second semiconductor layer 4 having the reverse conductivity type is applied. Accordingly, minority carriers are injected into the first semiconductor layer 3, and the second semiconductor layer 4 and the first semiconductor layer 3
Carriers are recombined at the interface of the semiconductor junction on the first semiconductor layer 3 side, which is the interface of the above, to emit light. The emitted light passes through the second semiconductor layer 4, the third semiconductor layer 5, and the insulating layer 7 and is extracted to the outside.

[0005]

However, in the above-described conventional semiconductor light emitting device, light emitted at the semiconductor junction is extracted in the direction in which the upper electrode 8 of the semiconductor substrate 1 is provided. When the device is mounted on a supporting substrate (not shown) and connected to an external circuit, the upper electrode 8 must be connected to the external circuit by a wire bonding method, and connection to the external circuit is complicated. There is a problem that the reliability is low.

That is, the face-down bonding method such as solder bump bonding or micro-bump bonding allows the above-described semiconductor device to be firmly fixed on the supporting substrate at the same time as the connection of the external circuit. Although the connection operation is simple and the connection work is simple, the conventional semiconductor light emitting element extracts light to the portion where the upper electrode 8 is provided, so that the upper electrode 8 is connected to an external circuit on the supporting substrate by a face-down bonding method. Then, light is blocked by the support substrate.

In the conventional semiconductor light emitting device, light emitted at the semiconductor junction is extracted from the upper electrode 8 side.
The upper electrode 8 must be formed as small in area as possible so as not to block light extraction. As a result, there is a problem that the current flows locally at the semiconductor junction and the light emission intensity is weak.

The present invention has been made in view of such problems of the prior art, and a semiconductor light emitting device can be attached to a supporting substrate by a face down bonding method, and a semiconductor light emitting device can be mounted by a face down bonding method. It is an object of the present invention to provide a semiconductor light emitting device capable of effectively extracting light even when the device is mounted on a support substrate.

[0009]

In order to achieve such an object, in a semiconductor light emitting device according to the present invention, an island-shaped portion comprising at least two semiconductor layers of different conductivity types is provided on a semiconductor substrate, A translucent insulating film is applied from the side of the island to the semiconductor substrate, and the upper surface and the side of the island are covered with a first electrode except for one side of the island. A second electrode was formed on the semiconductor substrate in the vicinity of the electrode.

[0010]

With the above arrangement, light emitted from the semiconductor junction is extracted from one side of the island which is not covered with the first electrode, and the first electrode and the second electrode are connected to the semiconductor substrate. Since the semiconductor light emitting device is formed on the same surface, the semiconductor light emitting device thus formed can be mounted on a supporting substrate by a face-down bonding method. Further, the first electrode can be formed over a wide area on the upper surface of the island-shaped portion, and current can flow over a wide area on the semiconductor junction, so that a semiconductor light emitting device having a high light emission intensity Can be provided.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a sectional view showing an embodiment of a semiconductor light emitting device according to the present invention, and FIG. 2 is a perspective view of the semiconductor light emitting device, wherein 1 is a semiconductor substrate, 2 is a buffer layer, and 3 has the same conductivity type as the semiconductor substrate 1. The first semiconductor layer 4 is a second semiconductor layer containing an impurity of the opposite conductivity type that forms a semiconductor junction with the first semiconductor layer 3, 5 is a third semiconductor layer, and 6 is an ohmic contact with the upper electrode 8. An ohmic contact layer 7 containing a large amount of impurities of the opposite conductivity type for making contact is an insulating film made of, for example, silicon nitride (SiNx).

The semiconductor substrate 1 is made of, for example, n-GaAs.
Or a single crystal silicon substrate cut off from the (100) plane by 2 ° from the (100) plane, and a donor made of antimony (Sb) is used. A semiconductor substrate containing about ¹⁹ / cm ³ is used.

On the semiconductor substrate 1, a buffer layer 2 containing one conductivity type, for example, an n-type impurity is formed. The buffer layer 2 is made of, for example, III-V such as GaAs.
It is made of a group III compound semiconductor film or the like. This buffer layer 2 has 10 ¹⁸ donors / cm ³ made of silicon (Si) or the like.
It is formed to a thickness of about 1 to 1.5 μm by a MOCVD method appropriately employing a two-step growth method or a thermal cycle method. That is, the temperature in the MOCVD apparatus is 900 to 1000 ° C.
After heating once in TMG, lower to 400-450 ° C
GaAs by MOCVD using a gas, AsH ₃ gas, and SiH ₄ gas as a semiconductor impurity element source.
While growing the film, raise the temperature to 600-650 ° C.
aAs film is grown (two-step growth method), and then 300 to 9
The temperature is raised and lowered at 00 ° C. (thermal cycle method) to generate internal stress due to the difference in thermal expansion coefficient, and the silicon substrate 1
And the GaAs layer 2 are formed so as to reduce misfit transition caused by the difference in lattice constant.

On the buffer layer 2, a first semiconductor layer 3 containing an impurity of one conductivity type is formed. The first semiconductor layer 3 is made of, for example, Al _x Ga ₁ -x As, and has 10 ¹⁷ donors made of silicon or the like.
It contains about ³ cm ³ . The first semiconductor layer 3 made of Al _x Ga ₁ -x As or the like is made of TMAl gas, TMGa
Formed by MOCVD using a gas, an AsH ₃ gas, and a SiH ₄ gas serving as an impurity element for a semiconductor;
The mixed crystal ratio X of 1 is set to, for example, 0.3 or 0.65.

On the first semiconductor layer 3, a second semiconductor layer 4 is formed. The second semiconductor layer 4 is made of, for example, Al _y Ga _1-y As and has a reverse conductivity type, for example, p-type.
It contains about 10 ¹⁷ acceptors such as zinc (Zn) serving as impurities for a type semiconductor per cm ³ . This Al _y Ga
The second semiconductor layer 4 made of _1-y As or the like is formed by a MOCVD method using a TMAl gas, a TMGa gas, an AsH ₃ gas, and a DMZn gas serving as a semiconductor impurity element source, and has a wavelength of about 700 nm. In order to emit light, the mixed crystal ratio y of Al is set to, for example, 0.3. The first semiconductor layer 3 and the second semiconductor layer 4 described above.
Thus, a semiconductor junction is formed, and a light emitting unit is formed.

On the second semiconductor layer 4, a third semiconductor layer 5 is formed. The third semiconductor layer 5 is made of, for example, Al _z Ga _{1 -z} As and has a thickness of about 1 μm. The third semiconductor layer 5 made of Al _z Ga ₁ -z As or the like also has a TMAl gas, a TMGa gas,
sH ₃ gas, and opposite conductivity type, using DMZn gas as a semiconductor impurity element source exhibiting a p-type MOCV
It is formed by Method D. Al _{z of} the third semiconductor layer 5
The mixed crystal ratio z of Al of Ga _1-z As is set, for example, at z = 0.65 in order to increase the band gap.

On the third semiconductor layer 5, an ohmic contact layer 6 containing a large amount of impurities of the opposite conductivity type is formed. The ohmic contact layer 6 is made of, for example, a III-V compound semiconductor such as GaAs. In order to make ohmic contact with the upper electrode 7, zinc (Z
n) and the like are contained in a high concentration.

The buffer layer 2, the first to third semiconductor layers 3, 4, 5, and the ohmic contact layer 6 on the semiconductor substrate 1 are formed of sulfuric acid (H ₂ SO ₄₎ so as to form the contour of the light emitting element. ), Hydrogen peroxide (H ₂ O ₂ ), water (H
It is formed in an island shape by etching with an etching solution composed of a mixed solution such as ₂ O).

A light-transmitting insulating film 7 is formed on side surfaces of the semiconductor substrate 1 and the plurality of semiconductor layers 2 to 6 formed in an island shape. The insulating film 7 is formed of, for example, a silicon nitride film (SiN _x ) or a silicon oxide film (SiO ₂ ). The insulating film 7 is formed by, for example, a plasma CVD method using a silane gas, an ammonia gas, a laughing gas, or the like.

A first electrode 8 is formed on the semiconductor layers 2 to 6 except for one side, and a second electrode 9 is formed on the semiconductor substrate 1. . The first electrode 8 and the second electrode 9 are made of Ag, Ag
/ Zn or Cr / Au or the like, and is formed to a thickness of about 5000 ° by a vapor deposition method or the like.

In the semiconductor light emitting device configured as described above, when a current is applied in the forward bias direction with the first electrode 8 being negative and the second electrode 9 being positive, the first semiconductor 8 Minority carriers are injected into the layer 3, and recombine at the interface between the first semiconductor layer 3 and the second semiconductor layer 4 at the interface between the semiconductor junction and the first semiconductor layer 3 to emit light. In the present invention, since the first electrode 8 is formed except for one side surface portion of the semiconductor layers 2 to 6, light emitted at the semiconductor junction portion is generated on one side surface where the first electrode 8 is not formed. The part will be taken out only.

FIG. 3 shows a semiconductor light emitting device 10 according to the present invention.
FIG. 3 is a view showing a state in which is bonded face down to a support substrate 11. On the support substrate 11, conductor patterns 12, 13 for an external circuit are formed. This support substrate 11
The semiconductor light emitting element 10 is
The first electrode 8 and the second electrode 9 are opposed to each other and aligned, and fixed by, for example, a microbump bonding method. That is, a liquid or sheet-shaped resin 14 which is cured by light or heat is applied to the vicinity of the electrodes 8 and 9 of the semiconductor light emitting device 10 or the vicinity of the conductor patterns 12 and 13 of the support substrate 11. The first electrode 8 and the second electrode 9 of 10 are precisely aligned with the conductor patterns 12 and 13 of the support substrate 11, and the resin 1 is pressed by light or heat while pressing the semiconductor light emitting element 10.
By curing the semiconductor light-emitting device 4, the semiconductor light-emitting element 10 is fixed on the support substrate 11 to form a semiconductor light-emitting device. In this case, the fixing and the electrical connection of the semiconductor light emitting element 10 can be performed simultaneously. That is, in the present invention, since the first electrode 8 and the second electrode 9 are formed on the same surface of the semiconductor substrate 1, it becomes possible to mount the semiconductor substrate 1 on the support substrate by a face-down bonding method.

In the present invention, a plurality of semiconductor layers including the buffer layer 2, the first semiconductor layer 3, the second semiconductor layer 4, the third semiconductor layer 5, and the ohmic contact layer 6 are provided. The present invention is not limited to this example, and it suffices if there are at least two semiconductor layers capable of forming a semiconductor junction.

FIG. 4 shows a second embodiment. In this embodiment, a plurality of islands I composed of semiconductor layers 2 to 6 are provided on a semiconductor substrate, and the plurality of islands I are arranged in a staggered manner. By arranging the islands I in a staggered manner in this manner, the islands I can be formed on the semiconductor substrate 1 with high definition. That is, when the islands I are formed by etching the semiconductor layers 2 to 6, the side surfaces of the islands I are also etched to the same depth as the height of the islands I (side etching).
Is done. Therefore, even when the etching is performed with the distance between the islands I approaching 0, the distance between the adjacent islands I is
It cannot be smaller than the height of the islands I. However, when the islands I are formed in a zigzag pattern as in the second embodiment, the interval between the islands I in the light emitting direction can be made zero, and extremely high definition can be achieved.

[0025]

As described above, according to the semiconductor light emitting device of the present invention, an island-shaped portion composed of at least two semiconductor layers having different conductivity types is formed on a semiconductor substrate, and the side surface of the island-shaped portion is formed. And a semiconductor substrate, a light-transmitting insulating film is formed, and the upper surface and side surfaces of the island-shaped portion are covered with a first electrode except for one side surface of the island-shaped portion. Since the second electrode is formed on the semiconductor substrate,
Light emitted from the semiconductor junction is extracted from one side of the island that is not covered with the first electrode, and the first electrode and the second electrode are formed on the same surface of the semiconductor substrate. The semiconductor light emitting device thus formed can be mounted on a supporting substrate by a face-down bonding method. Further, the first electrode can be formed over a wide area on the upper surface of the island-shaped portion, and current can flow over a wide area on the semiconductor junction, so that a semiconductor light emitting device having a high light emission intensity Can be provided.

[Brief description of the drawings]

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

FIG. 2 is a perspective view of a semiconductor light emitting device according to the present invention.

FIG. 3 is a view showing a state where the semiconductor light emitting device according to the present invention is mounted on a support substrate.

FIG. 4 is a view showing another embodiment of the semiconductor light emitting device according to the present invention.

FIG. 5 is a diagram showing a conventional semiconductor light emitting device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Semiconductor substrate, 2-6 semiconductor layers, 7 ... Translucent insulating film, 8 ... 1st electrode, 9 ... 2nd electrode, I
... Island.

Claims (2)

(57) [Claims] An island-shaped portion comprising at least two semiconductor layers of different conductivity types is provided on a semiconductor substrate, and a light-transmitting insulating film is applied from a side surface of the island-shaped portion to the semiconductor substrate. A semiconductor light emitting device comprising: a first electrode covering an upper surface and a side surface of the semiconductor substrate except for one side surface of the island-shaped portion; and forming a second electrode on the semiconductor substrate near the first electrode. 2. The semiconductor light emitting device according to claim 1, wherein a plurality of said island-shaped portions are provided on said semiconductor substrate, and said plurality of island-shaped portions are arranged in a staggered manner.