JP2003110148A - Semiconductor light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor light-emitting device which exhibits high heat-dissipating efficiency. SOLUTION: The semiconductor light-emitting device has a light-emitting element which is composed of semiconductor elements on a substrate 11 and is mounted on a mount substrate. First bumps 31 which are connected to the side of the mount substrate with electrical continuity and second bumps 32 which are connected to the mount substrate with electrical insulation are provided. When heat is far from the first bumps 31 and is not sufficiently dissipated to the side of the mount substrate, it is efficiently led via the second bumps 32 to the side of the mount substrate. In this way, high heat-dissipating efficiency can be attained.

Description

Detailed Description of the Invention

[0001]

2. Description of the Related Art In recent years, a semiconductor device made of a nitride semiconductor has been used for various purposes as a light emitting device capable of emitting blue light.

A semiconductor device formed by using this nitride semiconductor is usually formed by sequentially stacking an n-type nitride semiconductor layer, a nitride semiconductor active layer, and a p-type nitride semiconductor layer on a sapphire substrate. An n-side ohmic electrode is formed on the exposed n-type nitride semiconductor layer by removing a part of the layer and the nitride semiconductor active layer, and a p-side ohmic electrode is formed on the p-type nitride semiconductor layer. .

A conventional light emitting device using a nitride semiconductor outputs light emitted from the p-type nitride semiconductor side through a positive electrode having a light-transmitting property formed on the p-type nitride semiconductor layer. It is classified into a so-called semiconductor-side light emitting type and a substrate-side light emitting type that outputs light emitted through a light-transmitting sapphire substrate.

Among the nitride semiconductor light emitting devices, the gallium nitride based semiconductor device, in particular, has a characteristic that the resistance value of the p-type nitride semiconductor is generally relatively high, so that the p-type nitride semiconductor layer is almost entirely transparent. A current is injected into the entire nitride semiconductor active layer by forming an optical p-side ohmic electrode. Further, in the nitride semiconductor light emitting device, it is necessary to form the n electrode on a part of the n-type nitride semiconductor as described above and to form both the p side electrode and the n side electrode on the growth surface side of the nitride semiconductor layer. Therefore, it is difficult to inject current into the entire nitride semiconductor active layer. Therefore, an n-side ohmic electrode is formed at one corner of the n-type nitride semiconductor layer, and the other corner on the p-side ohmic electrode that is diagonal to the one corner is electrically connected to the outside. A p-side pad electrode for conduction is formed, and n is formed on the n-side ohmic electrode.
A pad electrode on the side is formed so that current can be easily injected into the entire active layer of the nitride semiconductor.

That is, the gallium nitride based semiconductor device is constructed by using an insulating sapphire substrate, and the p-type nitride semiconductor has a relatively large resistance value. Since there is a situation different from that of the element, the p-side ohmic electrode is provided on almost the entire surface of the p-type gallium nitride based semiconductor layer, and the n-side ohmic electrode and the p-side pad electrode are formed at diagonal positions. It has a unique structure so that current can be efficiently injected into the active layer.

Further, in the conventional nitride semiconductor light emitting device, normally, in order to protect the semiconductor layer and the electrode layer, n
An insulating protective film is formed on the side pad electrode and the p-side pad electrode except for the connection portion with the external circuit. In the conventional nitride semiconductor light emitting device configured as described above, the positive and negative pad electrodes are connected to the external circuit by facing the wiring substrate, and are connected by, for example, flip chip bonding, and the emitted light is It is output through the transparent substrate.

[0007]

However, when trying to obtain a large area nitride semiconductor light emitting device, especially a gallium nitride based semiconductor device by the above method, the following problems occur. The p-side ohmic electrode described above is p
Type gallium nitride-based semiconductor layer is provided on almost the entire surface and an n-side ohmic electrode and a p-side pad electrode are formed in diagonal positions, a unique structure is required for forming a large-area light emitting device. The current injected into the active layer is n
It can be regarded as almost constant within a certain distance from the side ohmic electrode, but if it exceeds the certain range, it is rapidly reduced and uniform light emission becomes difficult.

For example, in a gallium nitride-based light emitting device formed by stacking an n-type nitride semiconductor layer, a nitride semiconductor active layer, and a p-type nitride semiconductor layer on a sapphire substrate, within 250 μm from the n-side ohmic electrode. The current injected into the nitride semiconductor active layer at a distance of is almost constant.
When the distance is more than 50 μm, it sharply decreases. Actually 220
The current injected into the nitride semiconductor active layer gradually begins to decrease when the distance is more than μm, but the current value can be regarded as substantially constant up to 250 μm.

This phenomenon (the nitride semiconductor active layer is 25
The phenomenon that the injected current sharply decreases when the distance is 0 μm or more) is considered to be caused by the resistance value of the n-type nitride semiconductor layer, but normally, the resistance value of the n-type nitride semiconductor layer is used. It has been confirmed that there is almost no change in the range of.

From the above knowledge, a rectangular nitride semiconductor active layer which is long in one direction and a p-type nitride semiconductor active layer are formed on the n-type nitride semiconductor layer.
Even when the type nitride semiconductor layer is formed, if the distance from the n-side ohmic electrode is within a certain distance (within a certain range), preferably within 250 μm, the nitride semiconductor active layer is almost evenly formed. Current can be injected.

To obtain a large-area light emitting device, the p-side ohmic electrode is provided on almost the entire surface of the p-type gallium nitride based semiconductor layer, and the n-side ohmic electrode and the p-side pad electrode are located at diagonal positions. It is difficult to increase the size of the peculiar structure of forming the same by a similar shape for the above reason. Therefore, a light emitting device in which a nitride semiconductor active layer is present at a desired constant distance on one substrate is formed. It is preferable that a plurality of linear or arrayed elements are arranged.

However, in the case where a plurality of semiconductor elements are arranged on a substrate by the above method and a large-area light emitting element (LED chip) in which each semiconductor element is connected is mounted on a mounting substrate, a nitride semiconductor active layer is formed. Although a current can be injected substantially uniformly into the substrate, since the area becomes large, there arises a problem of heat dissipation from heat generated from the active layer. A semiconductor element that is mounted on a substrate with a conventional area and is used as a light emitting device generates heat from a pair of positive and negative bumps provided on a pad electrode formed on the ohmic electrode for electrical conduction with the outside. Heat was dissipated, and there was not much need to consider heat dissipation. However, for example, when the area is widened and heat is accumulated in the portion away from the pair of positive and negative bumps without sufficient heat dissipation, the element is deteriorated, and the life and constant light emission output are maintained. Problems such as continuing to affect the light emitting ability will become apparent.

Therefore, an object of the present invention is to provide a semiconductor light emitting device having an improved heat dissipation of the light emitting element and having an excellent light emitting ability such as keeping the life and maintaining a constant light emitting output, and further, in a large area. Another object of the present invention is to provide an integrated semiconductor light emitting device having good heat dissipation efficiency.

[0014]

To achieve the above object, a semiconductor light emitting device according to the present invention is a semiconductor light emitting device in which a light emitting element having a semiconductor element formed on a substrate is mounted on a mounting base. , The semiconductor light emitting device,
A first bump electrically connected to the mounting substrate side and connected thereto; and a second bump electrically insulated and connected to the mounting substrate side, and other than the first bump. By providing the second bump, heat dissipation can be improved.

In a semiconductor light emitting device having a plurality of semiconductor elements formed on a substrate and mounted on a mounting base, the semiconductor light emitting device includes a first bump electrically connected to the mounting base and connected to the first bump. , And a second bump electrically insulated and connected to the mounting substrate. The first bumps are connected to the positive electrode and the negative electrode of the semiconductor element, respectively, and are electrically connected to the outside. In addition to the first bumps formed on the electrodes connected to the outside, By providing one or a plurality of bumps as the second bump, even if the heat deposited on the portion away from the first bump on the electrode connected to the outside, that is, the portion where heat conduction is difficult, By providing the bumps, the contact area with respect to the mounting base increases, so that the efficiency of heat dissipation to the mounting base improves, and as a result, deterioration of the element can be prevented and the life of the semiconductor light emitting device can be improved.

The number of the second bumps can be appropriately determined according to the distance between a pair of positive and negative electrodes connected to the outside.

Further, the second bump is provided on the connection electrode of each semiconductor element, which is a large-area light emitting element by electrically connecting two adjacent semiconductor elements among the semiconductor elements. It is preferable because heat can be dissipated relatively uniformly. It is preferable that the second bump is formed of the same metal material as that of the first bump and is provided on the connection electrode rather than on the insulating protective film because it can be easily formed in the process. By providing the second bumps as described above, the heat radiation effect is particularly expected in a large-area light emitting element or the like in which the distance between the bumps is long and heat is easily accumulated.

Further, the substrate has a light-transmitting property, and a remarkable effect is exhibited in a semiconductor element mounted by flip-chip with the light extraction surface on the substrate side. Further, when the light extraction surface is on the substrate side by such a flip chip mounting method, the light emission efficiency is also improved.

In the semiconductor device, an n-type nitride semiconductor layer, a nitride semiconductor active layer, and a p-type nitride semiconductor layer are sequentially stacked, and the p-type nitride semiconductor and a part of the nitride semiconductor active layer. Is formed, and an n-side ohmic electrode is formed on the exposed n-type nitride semiconductor layer, and a p-type ohmic electrode is formed on the p-type nitride semiconductor layer.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. A semiconductor light emitting device according to an embodiment of the present invention is a so-called substrate side light emitting type semiconductor element that outputs light emitted through a substrate having a light-transmitting property. For example, as shown in FIG. On the substrate, an n-type nitride semiconductor layer, a nitride semiconductor active layer, and a p-type nitride semiconductor layer are laminated,
In a semiconductor device in which a side ohmic electrode is formed on each layer and a p-side pad electrode is formed on a part of the p-side ohmic electrode, a first metal layer is formed on the n-side ohmic electrode and the p-side pad electrode. Bumps are provided,
Further, second bumps made of the same metal material as the first bumps are provided and mounted on the mounting substrate.

Usually, the bump is provided between the p-side and n-side electrodes and the mounting base when the semiconductor device is mounted on the mounting base by face-down mounting, and is used for the purpose of joining the semiconductor device and the mounting base. More specifically, the p-side ohmic electrode is formed on the entire surface of the n-type nitride semiconductor layer, the active layer, and the p-type nitride semiconductor layer, which are sequentially stacked on the substrate made of sapphire. A pad electrode is formed in part. On the other hand, the p-type semiconductor layer and the active layer are removed, and an n-side ohmic electrode is formed on the exposed n-type nitride semiconductor layer. An insulating protection film is formed on the p-side pad electrode and the n-side ohmic electrode. Solder using a low melting point metal such as tin-silver-copper alloy (Sn-Ag-Cu) or tin-copper-nickel alloy (Sn-Cu-Ni) on the p-side pad electrode and the n-side ohmic electrode. A first bump consisting of

In addition to the above materials, the bumps used in the present invention include tin (Sn), gold (Au), indium (In),
Gold-lead alloy (Au-Pb), tin-platinum alloy (Sn-P
t), indium-tin alloy (In-Sn), eutectic tin-lead (Sn-Pb), and other materials generally used as bumps. Especially Sn-Ag-Cu and Sn-C
u-Ni is excellent in mountability. By providing the first bumps made of these materials, the semiconductor element is bonded to the mounting substrate, and the bumps on the n-side and p-side electrodes are electrically connected to the outside.

The bumps can be formed by welding using solder material, plating, balls used for stud bumps, screen printing, or plating using gold, balls, and screen printing using polymers. , On the mounting substrate facing the electrode,
Alternatively, it is formed by forming the bumps at either position on the electrode or on the mounting substrate facing the electrode and joining the bumps to the mounting substrate. Particularly, in the case of bumps using gold, mounting is performed. It is preferable that gold is formed on the substrate side at a position facing the bump when bonding, and the gold bump is formed by gold-gold bonding.

In the semiconductor light emitting device according to the present invention, the first bumps 31 formed on the n-side ohmic electrode 14 and the p-side pad electrode 16 are formed on the portions other than the n-side and p-side electrodes. One or more second bumps 32 are provided in another portion, and the second bumps 3 are provided.
2 is provided to guide the heat generated from the active layer 10 which is difficult to be transferred from the first bump 31 on the n-side or p-side electrode to the mounting substrate 24 to the mounting substrate 24. The second bump 32 is not electrically connected to the outside.

The second bump 32 may be made of the same material as the first bump 31 such as metal or alloy thereof, or other material having good thermal conductivity. Further, as a method of forming the second bump,
The same method as the method of forming the first bump described above can be used.

Further, the bonding pad 19 is provided between the second bump 32 and the insulating protective film on the nitride semiconductor layer.
May be formed.

By forming the bonding pad 19 between the bump and the insulating protective film, the alignment when forming the second bump 32 is facilitated and the bump is easily provided.

When the bonding pad 19 is formed on the ohmic electrode 15 by opening the insulating protective film 17, heat is transferred without passing through the insulating protective film 17, so that the heat dissipation effect can be more efficiently enhanced. However, considering the thickness of the second bump 32 on the bonding pad 19 so as not to affect the device, the n-side ohmic electrode 14 and the p-side pad electrode that are electrically connected to the external electrode are taken into consideration. It may be a metal made of the same material as 16 or other metal.

In this embodiment, solder is used as the bump. However, bumps not using solder such as gold may be formed. In that case, the mounting method on the mounting substrate is as follows.
(1) A method of newly forming and connecting solder between the bump and the mounting base, and (2) A method of connecting between the bump and the mounting base via an anisotropic conductive film or an anisotropic conductive paste. and so on.

Further, in the present embodiment, the p-side pad electrode and the n-side pad electrode (or the n-side ohmic electrode when the n-side pad electrode is not provided) itself is the first bump, and the bonding pad itself is the second bump. It is also possible to mount it as a bump on the mounting substrate.

The present embodiment is also applicable to a case where a plurality of semiconductor elements are arranged to form a large area light emitting element.

By satisfying these conditions, the heat dissipation property of the semiconductor device having a problem that the distance from the bump on the electrode is long and the heat is not sufficiently dissipated, as seen in, for example, a large-area light emitting device, is improved. Since the heat generated from the active layer is radiated without being accumulated, deterioration of the semiconductor light emitting device can be suppressed. Embodiment 2 A nitride semiconductor light emitting device of Embodiment 2 has three rectangular semiconductor elements 1, 2 and 3 arranged in parallel with each other on a sapphire substrate of 1000 μm × 1000 μm as shown in FIG. By providing a plurality of bumps on the connection electrodes connecting each element to increase the heat dissipation and increasing the contact area with the mounting substrate 24, it is possible to easily and uniformly dissipate the heat in the process. Therefore, the temperature rise of the light emitting element is suppressed in the portion where the distance from the electrode is relatively large and the heat dissipation is insufficient. As a result, the semiconductor has a long life and a stable and uniform light emitting ability even for a long time. A light emitting device can be realized.

More specifically, when a plurality of semiconductor elements are arranged to obtain a large-area light emitting element as in the second embodiment of the present invention, n provided on an n-type nitride semiconductor is used.
It is desirable that the distance between the side ohmic electrode and the other long sides of the nitride semiconductor active layer and the p-type nitride semiconductor layer be a preferable distance, and a plurality of devices be formed on the substrate to have a large area. As described above, the preferable distance is the maximum value of the distance at which the current injected into the nitride semiconductor active layer is substantially constant, which changes depending on the resistance value of the nitride semiconductor.

However, when a large-area light emitting device is formed and flip-chip mounted in this way, bumps (first bumps 31) are formed on a pair of positive and negative electrodes connected to the outside, and Although the light emitting element is connected to the mounting substrate 24 via the bump 31 of No. 1, the other portion is filled with a sealing resin called underfill or the like, and the resin is compared with a metal, a semiconductor, or an insulating protective film. Since the thermal conductivity is low, the heat generated in these other parts is deposited with almost no radiation.

Therefore, similar to the first bumps 31 (which are connected to the external electrodes and are electrically connected) on the connection electrodes, which connect the respective elements formed in a line. By forming the second bumps 32, the second bumps 32 can be brought into contact with the semiconductor element and the mounting substrate 24 at the time of mounting in an electrically independent insulating state, and the activity generated near the bumps can be achieved. Since the heat from the layers is conducted to the mounting substrate 24, it is possible to improve the heat dissipation of the light emitting element.

Further, by providing the second bump 32 on the connection electrode, the alignment for forming the second bump is easy, and when the shape and size of the second bump are constant, By uniformly radiating heat, it becomes possible to emit light uniformly for a long time, and it is possible to prevent uneven light emission.

Preferred forms of the second embodiment are listed below. FIG. 3 is a schematic cross-sectional view of the semiconductor light emitting device according to the present embodiment as seen from a cross section.

N-type nitride semiconductor layer 1 on sapphire substrate
2. Nitride semiconductor active layer 10 and p-type nitride semiconductor layer 13 are sequentially stacked to form a plurality of nitride semiconductor light emitting devices, and two adjacent semiconductor devices are electrically connected by a connection electrode. However, in the case of a large-area light emitting element, the external connection electrode 22 (in the figure, n is formed on the n-side ohmic electrode 14 and the p-side pad electrode 16).
Side 22a, and p side 22b) is provided with a first bump 31 made of a metal material, and the same as the first bump 31 is provided on the connection electrode 21 electrically connecting each element. A second bump 32 made of a metal material is provided.

By providing the second bump 32, the heat radiated from the first bump 31 is not sufficiently radiated, and the accumulated heat is guided to the mounting substrate 24 via the second bump 32.

Preferably, the insulating protection film 18 on all the connection electrodes 21 electrically connecting mutually adjacent semiconductor elements to each other is opened, and the second bumps 3 are formed.
2 is provided, and by providing the second bumps 32 made of the same component on the connection electrode 21 made of metal, heat dissipation is further enhanced as compared with the case where the bumps are provided on the insulating protective film. .

A bonding pad made of the same metal material as the pad electrode may be formed between the second bump 32 and the connection electrode 21.

Further, the second bumps 32 which are not electrically connected to the outside and are present in an insulating state, and the bonding pads on which the second bumps are formed are more in contact with the mounting substrate 24 when a plurality of bonding pads are formed. This is preferable because it improves heat dissipation.

The second bump 32 may be made of a metal similar to that of the first bump 31 or an alloy thereof, or a metal made of another material having a high thermal conductivity, preferably. The bonding pad formed under the second bump 32 is made of a metal having a higher thermal conductivity.

Further, the mounting substrate 24 has a shape such that a metal having a high thermal conductivity is embedded on the surface of the mounting substrate 24 or in a state where the mounting substrate 24 penetrates the mounting substrate 24. It is more preferable because the heat dissipation effect is enhanced.

The (first and second) bumps used in the second embodiment are similar to those of the first embodiment in that Sn-Ag- is used.
Cu and Sn-Cu-Ni, Sn, Au, In, Au
Materials commonly used as bumps, such as -Pb, Sn-Pt, In-Sn, and Sn-Pb, may be mentioned. Especially S
n-Ag-Cu and Sn-Cu-Ni are excellent in mountability.

Further, as the method of forming the bumps, similarly to the first embodiment, the welding using the solder material, the plating,
Balls used for stud bumps, screen printing,
Alternatively, plating using gold, balls, screen printing using a polymer, etc. may be mentioned. Either on the electrode, on the mounting substrate facing the electrode, or on both the electrode and the mounting substrate facing the electrode. It is formed by forming the above-mentioned bump at the position of and bonding it to the mounting substrate. Particularly, in the case of a bump using gold, the mounting substrate side is also provided with gold at a position facing the bump when bonding. It is preferable to form the gold bumps by gold-gold bonding.

In this embodiment, solder is used as the bump. However, bumps not using solder such as gold may be formed. In that case, the mounting method on the mounting substrate is as follows.
(1) A method of newly forming and connecting solder between the bump and the mounting substrate, and (2) A method of connecting between the bump and the mounting substrate via an anisotropic conductive film or an anisotropic conductive paste. and so on.

Further, in the present embodiment, the external connection electrode is formed by increasing the film thickness of the p-side pad electrode and the n-side pad electrode (or the n-side ohmic electrode when the n-side pad electrode is not provided). It can be omitted.

Furthermore, the external connection electrode (p-side pad electrode and n-side pad electrode when the external connection electrode is not provided) itself is used as the first bump, and the connection electrode or the bonding pad itself is mounted as the second bump. It can also be mounted on a substrate.

In the second embodiment, the case where the number of semiconductor elements is three has been described, but the present invention is not limited to this, and may be one configured by using two semiconductor elements, or three. It may be composed of the above semiconductor elements.

[0051]

Example 1 (Substrate) A substrate 11 made of sapphire (c-plane) is set in a MOVPE reaction vessel, the temperature of the substrate is raised to 1050 ° C. while flowing hydrogen, and the substrate is cleaned. Other examples of this substrate include a sapphire substrate whose main surface is the R surface and A surface, and spinel (MgAl ₂ O
_The insulating mounting substrate 24 such as ₄ ) may be used. After cleaning the (n-type nitride semiconductor) substrate, the n-type nitride semiconductor layer 12 is grown in the following order.

The substrate temperature is lowered to 510 ° C., and the substrate 11
A 100 Å growth of a GaN buffer layer is grown on top.

Next, after growing the buffer layer, the temperature is raised to 1050 ° C.
And an undoped GaN layer is grown to a thickness of 1.5 μm.

Subsequently, at 1050 ° C., Si was added to 4.5 × 10 5.
^{A 18} / cm ³ -doped GaN layer is grown to a thickness of 2.2 μm.

Next, at 1050 ° C., an undoped GaN layer having a thickness of 3000 Å and Si of 4.5 × 10 ¹⁸ /
A cm ³ -doped GaN layer is grown to 300 Å, and an undoped GaN layer is grown to a film thickness of 50 Å.

Subsequently, at the same temperature, the first layer made of undoped GaN is set to 40 Å and the temperature is set to 800 ° C., and then the second layer made of undoped In _0.13 Ga _0.87 N is formed.
Layer is grown to a film thickness of 20Å, these operations are repeated, and 10 layers are alternately laminated in the order of 1 + 2nd +, and finally the first layer is laminated to grow an n-type multilayer film layer. Let (Nitride Semiconductor Active Layer) Next, after growing the n-type nitride semiconductor layer 12, a barrier layer made of undoped GaN is grown to a film thickness of 200Å, and subsequently the temperature is set to 800 ° C. and Si is set to 5 × 10 ^17. / Cm ³ Doped In _0.3 Ga _0.7
A well layer made of N is grown to a film thickness of 30Å. Then, six barrier layers and five well layers are alternately laminated in the order of barrier + well + barrier + well to laminate the nitride semiconductor active layer 10 composed of multiple quantum wells with a total film thickness of 1350Å. (P-Type Nitride Semiconductor Layer) After the growth of the nitride semiconductor active layer 10, the p-type nitride semiconductor 13 is grown with the following structure.

First, at 1050 ° C., Mg was added at 5 × 10 ¹⁹ /
The third layer of p-type Al _0.1 Ga _0.9 N doped with cm ³ was grown to a thickness of 25 Å, and then the fourth layer of undoped GaN was grown to a thickness of 25 Å. The above procedure is repeated to grow a p-type multilayer film layer having a film thickness of 200Å, which is made of a superlattice in which four layers are alternately stacked in the order of 3 + 4.

Subsequently, at 1050 ° C., Mg was added at 1 × 10 ^20.
/ Cm ³ Doped p-type GaN layer 2700Å
To grow.

The wafer on which the nitride semiconductor has been grown as described above is taken out of the reaction container, and in order to expose the n-type nitride semiconductor layer 12, the SiO is formed on the p-type nitride semiconductor 13 except the exposed portion. ₂ mask is formed, etching is performed by RIE, and the n-type nitride semiconductor layer 12 is formed.
The surface of the (Si-doped GaN layer 122) is exposed.

Next, a resist is applied so that almost the entire surface of the p-type nitride semiconductor layer 13 is opened and the other parts are covered, and 100 Å of Ni and Pt is applied on the opened p-type nitride semiconductor layer.
After laminating 500 Å, anneal and p-side ohmic electrode 1
5 is formed. Further, Pt is 3000 Å and Ni is used as an electrode for connecting to the outside on a part of the p-side ohmic electrode 15.
The p-side pad electrode 16 of 60 Å is formed, and at the same time, one Pt / Ni (3000 Å / 60 Å) bonding pad 19 is formed on the p-side ohmic electrode other than the p-side pad electrode 16.

Next, the resist was removed, and this time, 200 Å W, 1000 Å Al, and 5 W on the n-type nitride semiconductor layer.
An n-side ohmic electrode 14 is formed by laminating 00Å, Pt of 3000Å, and Ni of 60Å in this order.

Next, an insulating protective film 1 made of SiO ₂ is formed on the entire surface.
7 is formed to a film thickness of 1.5 μm, and the p-side pad electrode 16 and a part of the n-side ohmic electrode 14 and the bonding pad 19 on the p-side ohmic electrode 15 are exposed by RIE. Finally, dicing is performed to obtain chips, and a nitride semiconductor light emitting device is obtained.

Next, the n-side ohmic electrode 14, the p-side pad electrode 16 and the bonding pad 19 of the nitride semiconductor element are immersed in a layer of molten solder made of Sn-Ag-Cu and pulled up to make Sn-Ag-Cu. A bump made of.

Further, in order to perform the face-down mounting (flip chip bonding) of the semiconductor element on which the bumps are formed on the mounting substrate 24, the n-type and p-type semiconductor layers are on the lower side, and the first bumps 31 are the mounting substrate. Wiring electrode 23
The first bumps 31 and the second bumps 32 made of the solder layer and the mounting substrate are connected to each other by welding by solder reflow at a position opposed to.

As described above, the nitride semiconductor light emitting device as shown in FIG. 1 is formed.

Although it is different from the present embodiment, the bumps may be provided on the p-side pad electrode, the n-side pad electrode may be formed on the n-side ohmic electrode, and the bumps may be provided thereon. .

[0067]

[Embodiment 2] Next, an embodiment of the second embodiment will be described below by taking as an example a configuration in which three semiconductor elements are arranged in a large area.

An n-type nitride semiconductor layer on a sapphire substrate,
The nitride semiconductor active layer and the p-type nitride semiconductor layer were formed as in Example 1.
Laminate in the same manner as.

Next, the wafer on which the nitride semiconductor has been grown is taken out from the reaction container, a SiO ₂ mask is formed on the entire wafer except for the portion where the separation groove is formed, and etching is performed by RIE until the sapphire substrate is reached. The isolation groove 41 is provided by this, and the semiconductor elements 1, 2, and 3 are formed.

Next, an n ohmic electrode on the n-type nitride semiconductor layer and a p ohmic electrode on the p-type nitride semiconductor layer,
The p-pad electrode is formed by the same method as in the first embodiment.

In the semiconductor elements 1, 2, and 3 of the semiconductor light emitting device of the second embodiment, each semiconductor layer and electrode have the structure shown in FIG. 3, and each is formed as follows.

The n-type nitride semiconductor layer 12 is preferably an undoped GaN layer having a thickness of 1.5 μm and a Si-doped GaN having a thickness of 2.2 μm formed on the sapphire substrate 11.
Layer, 3000 Å thickness undoped GaN layer, 300 thickness
Å Si-doped GaN layer, thickness 50 Å undoped Ga
It has a laminated structure of N layers and multilayer films. Thus, the n layer 12
With the above laminated structure, the forward voltage can be lowered and the luminous efficiency can be improved. The multilayer film layer 126
Is preferably made of undoped GaN and has a film thickness of 40 Å
First layer and undoped In _0.13 Ga _0.87 N
The second layer having a film thickness of 20 Å is alternately laminated to form 10 layers.

The resistivity of the entire n-layer of the laminated structure is substantially determined by the Si-doped GaN layer having a thickness of 2.2 μm, and the resistivity of this layer is 5.5 to 7.2 × 10.
It is preferable to set the film thickness in the range of ⁻³ Ωcm to 2.0 μm or more. By doing so, it is possible to more uniformly inject current into the entire nitride semiconductor active layer 10 and obtain more uniform light emission. .

In the GaN layer, 3 × 10 ^{18 to} 6
A Si-doped GaN film having a resistivity of 5.5 to 7.2 × 10 ⁻³ Ωcm can be formed by doping Si in the range of × 10 ¹⁸ cm ⁻³ .

The nitride semiconductor active layer 10 is a rectangle having substantially the same length as the n layer 12 and a width narrower than the n layer 12, and one long side thereof is substantially one long side of the n layer 12. Are formed on the n-layer 12 so as to correspond to. By forming in this way, a region for forming an n-side ohmic electrode is secured on the n layer 12 along the nitride semiconductor active layer 10.

Here, in the second embodiment, the width of the nitride semiconductor active layer 10 is 220 μm such that the distance between the long side located on the side away from the n-side ohmic electrode and the n-side ohmic electrode is 220 μm.
Was set.

The n-side ohmic electrode 14 has substantially the same length as the nitride semiconductor active layer 10, and is provided on the n layer 12 along the nitride semiconductor active layer 10 and in the vicinity of the nitride semiconductor active layer 10. Formed. Further, the interval between the n-side ohmic electrode 14 and the nitride semiconductor active layer 10 is set to 10 to 20 μm due to manufacturing restrictions, but in the present invention, the interval is preferably 10 μm or less. With this, the width in which the current can be uniformly injected can be increased.

The n-side ohmic electrode 14 is composed of the n-layer 1
In order to improve the ohmic contact with 2, it is preferable to use a layer containing W and Al, more preferably a W layer (200Å), a W layer (500Å), a Pt layer (3000).
Å) and Ni layer (60 Å) are sequentially laminated.

The p-type nitride semiconductor layer 13 has the same planar shape as the nitride semiconductor active layer 10 and is formed over the nitride semiconductor active layer 10.

In practice, the nitride semiconductor active layer 10 and the p-type nitride semiconductor layer 13 are formed by stacking the nitride semiconductor active layer 10 and the p-type nitride semiconductor layer 13 on the n layer 12 and then n. It is formed by collectively etching to expose the surface of the n-type nitride semiconductor layer 12 forming the side ohmic electrode 14.

The p-type nitride semiconductor layer 13 is 1500
Formed to a thickness of Å.

The p-side ohmic electrode 15 is formed on almost the entire surface of the p-type nitride semiconductor layer 13, and in order to obtain a good ohmic contact with the p-type nitride semiconductor layer 13, a Ni layer and a Pt layer are laminated. It is preferable that the Ni layer 100 Å and the Pt layer 500 Å
It is configured by stacking.

The p-side pad electrode 16 is, for example,
Made of Pt with a film thickness of 3000Å, p-side ohmic electrode 1
5 is formed along the long side of the p-side ohmic electrode 15 located on the side away from the n-side ohmic electrode 14.

The semiconductor device 1 configured as described above,
The elements 2 and 3 are separated from each other by the insulating protection film 17, and are connected by the connection electrode 21 as follows.

The insulating protection film 17 is formed so as to cover the entire element except the p-side pad electrode 16 and the n-side ohmic electrode 14 of each semiconductor element.

The connection electrode 21 is continuously formed on the n-side ohmic electrode 14 of the semiconductor element 1, the insulating protective film 17 formed in the isolation groove 41, and the p-type ohmic electrode 16 of the semiconductor element 2. The n-side ohmic electrode 14 of the semiconductor element 1 and the p-side ohmic electrode 16 of the semiconductor element 2 are connected.

The connection electrode 21 is similarly formed between the semiconductor element 2 and the semiconductor element 3, so that the n-side ohmic electrode 14 of the semiconductor element 2 and the p-side ohmic electrode 16 of the semiconductor element 3 are formed. Connected. The connection electrode 21 can be made of various metals such as Pt or Au, but in order to improve the adhesion to the p and n ohmic electrodes, Ti (for example, 400Å), Pt (for example, 6000Å), Au (for example, 1000Å), Ni
It is desirable to have a structure in which (for example, 60Å) are sequentially stacked.

Further, in this embodiment, the external connection electrode 22b made of the same material as the connection electrode 21 is further formed on the p-side pad electrode 16 of the semiconductor element 1, and the n of the semiconductor element 3 is formed.
An external connection electrode 22a made of the same material as the connection electrode 21 is formed on the ohmic electrode 14.

Next, the insulating protective film 18 is formed on the p-side external connection electrode 22b, the n-side external connection electrode 22a and each connection electrode 21.
It is formed so as to cover the entire element except the top.

Finally, dicing is performed to form a chip, and a nitride semiconductor light emitting device is obtained.

Next, the n-side external connection electrode 22a, the p-side external connection electrode 22b of the nitride semiconductor light emitting device and the connection electrode 21 for connecting the respective semiconductor devices are connected to Sn-Ag-C.
A bump made of Sn-Ag-Cu is formed by immersing in a molten solder layer made of u and pulling it up.

Further, in order to perform flip-chip bonding (face-down type mounting) on the semiconductor element on which the bumps are formed, to the mounting substrate 24, the n-type and p-type semiconductor layers are placed on the lower side, and the first bumps 31 are mounted. The first bumps 31 and the second bumps 32 made of the solder layer are connected to the mounting substrate by welding by solder reflow at a position facing the wiring electrode 23 of the substrate.

Although it is different from the present embodiment, the bump may be provided on the p-side pad electrode, the n-side pad electrode may be formed on the n-ohmic electrode, and the bump may be provided thereon.

As described above, a nitride semiconductor light emitting device which emits light in a large area as shown in FIG. 3 is formed. [Embodiment 3] Embodiment 3 has a structure as shown in FIG.
The bump forming method and the bump material are different from those of the second embodiment.

The semiconductor elements 1, 2, and 3 are formed on the substrate,
The external connection electrodes 22a and 22b are formed, and the insulating protective film 18 is formed.
It is formed in the same manner as in Example 2 until the above is formed.

Next, Au is added to the n-side external connection electrodes 22a, p.
It is formed on the side external connection electrode 22b and the connection electrode 21 that connects each semiconductor element to each other.

Further, this time, Au is also formed on the mounting substrate side at a position facing Au formed on the semiconductor element. Finally, ultrasonic vibration is applied to the Au formed on each of them to bond them, and the first bump 31 and the second bump 32 made of gold are formed.
To form.

As described above, a nitride semiconductor light emitting device which emits light in a large area as shown in FIG. 3 is formed.

[0099]

As described in detail above, in the semiconductor light emitting device according to the present invention, the same bumps as the bumps formed on the conventional n-side electrode and p-side electrode are replaced by the n-side electrode and the p-side electrode. By providing it in a portion other than the above, it is possible to enhance the heat dissipation effect and solve the problems relating to the deterioration of the element, the life, and the light emitting ability, which are caused by the accumulation of heat generated in the semiconductor element.

Further, as described in the second embodiment, the effect of the present invention becomes more remarkable in the semiconductor light emitting device in which a plurality of semiconductor elements are arranged and the light emitting area is large.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a semiconductor light emitting device showing a first embodiment of the present invention.

FIG. 2 is a schematic view of semiconductor elements 1, 2, and 3 according to a second embodiment of the present invention as viewed from a growth direction side.

FIG. 3 is a schematic cross-sectional view of a semiconductor light emitting device showing a second embodiment of the present invention.

[Explanation of symbols]

10 ... Active layer, 11 ... Substrate, 12 ... N layer (n-type nitride semiconductor layer), 13 ... P layer (p-type nitride semiconductor layer), 14 ... N-side ohmic contact Electrodes, 15 ... P-side ohmic electrode, 16 ... P-side pad electrode, 17, 18 ... Insulating protective film, 19 ... Bonding pad, 21 ... Connection electrode, 22 ... External connection Electrode (22a is n side, 22b is p
Side), 23 ... Wiring electrode, 24 ... Mounting substrate, 31 ... First bump, 32 ... Second bump, 41 ... Separation groove.

Claims (4)

[Claims] 1. A semiconductor light emitting device in which a light emitting element having a semiconductor element formed on a substrate is mounted on a mounting base, wherein the semiconductor light emitting device is a pair of positive and negative electrodes electrically connected to the mounting base. And a second bump electrically insulated and connected to the mounting substrate. 2. The semiconductor light emitting device has a plurality of light emitting elements on a substrate, and the second bump is formed in contact with a connection electrode electrically connecting two adjacent semiconductor elements. The semiconductor light emitting device according to claim 1, wherein: 3. The semiconductor light emitting device according to claim 1, wherein the substrate has a light-transmitting property, and the light extraction surface is on the substrate side. 4. The semiconductor device, wherein an n-type nitride semiconductor layer, a nitride semiconductor active layer, and a p-type nitride semiconductor layer are sequentially stacked, and one of the p-type nitride semiconductor layer and the nitride semiconductor active layer is formed. The n-side ohmic electrode is formed on the n-type nitride semiconductor layer exposed by removing the portion, and the p-side ohmic electrode is formed on the p-type nitride semiconductor layer. The semiconductor light emitting device according to claim 3.