JP2001044498A - Nitride semiconductor light emitting device - Google Patents

Abstract

[PROBLEMS] To provide a nitride semiconductor light emitting device capable of effectively preventing a short circuit between electrodes during manufacturing (during flip chip bonding). SOLUTION: An n-type nitride semiconductor layer formed on a light-transmitting substrate, an n-electrode and a p-type nitride semiconductor layer provided separately on the n-type nitride semiconductor layer, and p-type nitride Nitride semiconductor having a p-electrode provided in a part of the semiconductor layer, and an insulating protective film provided to cover each semiconductor layer and each electrode except for openings on the upper surfaces of the n-electrode and the p-electrode. In the light-emitting element, a first conductor is formed on the insulating protective film outside the opening on the p-electrode, and a second conductor is formed on the insulating protective film outside the opening on the n-electrode. Was formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip-type nitride semiconductor light-emitting device having n-type and p-type nitride semiconductor layers.

[0002]

2. Description of the Related Art In recent years, a light emitting device using a nitride compound semiconductor has attracted attention as a light emitting device capable of emitting blue light. A light emitting device using this nitride compound semiconductor is:
It has a layer structure in which an n-type nitride semiconductor layer is grown on a sapphire substrate, and a p-type nitride semiconductor layer is grown on the n-type nitride semiconductor layer directly or via a light emitting layer. Also, in a nitride semiconductor light emitting device formed using a sapphire substrate which is an insulator, unlike other light emitting devices formed using a conductive semiconductor substrate, a positive electrode and a negative electrode are on the same surface side. It is formed on a semiconductor layer. That is, the p-side positive electrode is formed on the p-type nitride semiconductor layer, and the n-side negative electrode is formed at a predetermined position at the p-type nitride nitride semiconductor layer (including the light-emitting layer when the light-emitting layer is provided. Is removed by etching to expose the upper surface of the n-type nitride semiconductor layer.

As described above, in a nitride semiconductor light emitting device,
Normally, the positive and negative electrodes are formed on the same surface side. To prevent a short circuit between the positive and negative electrodes, the insulating protective film is removed except for the part where the positive and negative electrodes are taken out (the part connected to the electrodes on the mounting board). It is formed and used by being mounted on a mounting substrate with the electrode surface facing up or down.

[0004]

However, when a conventional nitride semiconductor light emitting device is flip-chip bonded to a mounting substrate with the electrode surface facing down, for example, solder or the like is placed between the positive and negative electrodes formed on the same surface side. However, there is a problem that the conductive adhesive protrudes and short-circuits between the electrodes. Therefore, it is necessary to strictly control the amount of the conductive adhesive and the like in order to prevent a short circuit between the positive and negative electrodes at the time of manufacturing, which has caused a rise in manufacturing cost.

Accordingly, an object of the present invention is to provide a nitride semiconductor light emitting device having a structure capable of effectively preventing a short circuit between electrodes during manufacturing (during flip chip bonding).

[0006]

In order to achieve the above object, a nitride semiconductor light emitting device according to the present invention comprises: an n-type nitride semiconductor layer formed on a light-transmitting substrate; An n-electrode and a p-type nitride semiconductor layer provided separately from each other on a semiconductor layer, a p-electrode provided on a part of the p-type nitride semiconductor layer, and upper surfaces of the n-electrode and the p-electrode A nitride semiconductor light emitting device comprising an insulating protective film provided so as to cover each of the semiconductor layers and each of the electrodes except for the opening portion of the above. Forming a first conductor conductive to the p-electrode,
A second conductor, which is electrically connected to the n-electrode, is formed on the insulating protective film outside the opening on the n-electrode. With this configuration, the first conductor and the second conductor extending outward can guide the solder melted during flip chip bonding to the outside, so that the solder between the p electrode and the n electrode can be melted. It is possible to suppress the protruding solder, and to prevent a short circuit between the p electrode and the n electrode.

Further, in the nitride semiconductor light emitting device according to the present invention, the p-electrode is formed on a substantially entire surface of the p-type nitride semiconductor layer and a p-pad formed on a part of the full-surface electrode. The opening may be formed on the p-pad electrode in the insulating protective film.

Further, in the nitride semiconductor light emitting device according to the present invention, it is preferable that a distance between the first conductor and the second conductor is larger than a distance between the p pad electrode and the n electrode. , Which makes p more effective
A short circuit between the electrode and the n-electrode can be prevented.

[0009]

(Embodiment 1) Hereinafter, a nitride semiconductor light emitting device according to Embodiment 1 of the present invention will be described with reference to the drawings. The nitride semiconductor light emitting device according to the first embodiment is constituted by using a sapphire substrate 1 which is a light-transmitting substrate, and outputs light through the sapphire substrate 1. And has the following features. That is, the nitride semiconductor light emitting device according to the first embodiment has, as shown in FIG.
(1) A first conductor 10 extending on the insulating protective film 7 located outside the first opening 7b on the p-pad electrode 5 to be electrically connected to the p-pad electrode 5 is formed, and (2) an n-electrode 6 This is different from the conventional example in that the second conductor 11 that extends on the insulating protective film 7 located outside the upper second opening 7a and is electrically connected to the n-electrode 6 is formed. In this case, a short circuit between the p-electrode and the n-electrode is prevented. Hereinafter, the nitride semiconductor light emitting device of the first embodiment will be described in detail.

In the nitride semiconductor light emitting device of the first embodiment, the n-type nitride semiconductor layer 2 is formed on almost the entire surface of the sapphire substrate 1. The n-electrode 6 and the p-type nitride semiconductor layer 3 are formed on the n-type nitride semiconductor layer 2 so as to be separated from each other. Specifically, the p-type layer is formed on the n-type nitride semiconductor layer 2.
After the formation of the n-type nitride semiconductor layer, the p-type nitride semiconductor layer in the region where the n-electrode 6 is formed is removed by etching or the like to expose a part of the surface of the n-type nitride semiconductor layer 2. An n-electrode 6 is formed on the exposed surface of the n-type nitride semiconductor layer 2 so as to be electrically separated from the p-type nitride semiconductor layer 3.

The p-electrode 8 is composed of a full-surface electrode 4 formed on almost the entire surface of the p-type nitride semiconductor layer 3 and a p-pad electrode 5 formed on a partial surface of the full-surface electrode 4. . Preferably, the p-pad electrode 5 is formed as far as possible from the n-electrode 6. The insulating protective film 7 is formed so as to cover each semiconductor layer and each electrode formed as described above.
A first opening 7b is formed thereon, and a second opening 7a is formed on the n-electrode 6.

In the nitride semiconductor light emitting device of the first embodiment, the first opening 7b further extends on the insulating protective film 7 which is electrically connected to the p-pad electrode 5 and located outside the first opening 7b. The first conductor 10 is formed, and the second opening 7 is formed.
The second conductor 11 is formed which is electrically connected to the n-electrode 6 at a and extends on the insulating protective film 7 located outside the second opening 7a.

Here, the first conductor 10 is selected so as to satisfy the following conditions. That is,
that the adhesive strength between the p-pad electrode 5 and the insulating protective film 7 is strong, that the adhesive strength with the solder or the conductive paste is maintained for a long time, that the resistance value is low, That is, it is unlikely that one of the conductors penetrates the defect of the insulating protective film 7 and is short-circuited to the n semiconductor by the ion migration phenomenon. In order to satisfy these, the first conductor 10 is formed of one or more layers of metal films. An existing method that satisfies the above characteristics is used as a film forming method.

The first conductor 10 is made of Ti, Cr, Al,
Prepared by first depositing a metal or an alloy thereof mainly containing Zr, Mo, W, Hf, or Ni, and then depositing a metal or an alloy thereof mainly containing Au, Ni, or Pt. Is done. In the embodiment, Ti is formed first, and then Pt and Au are formed as final layers. In another embodiment, Cr is deposited first, and then Pt and Au are deposited as final layers.

The second conductor 11 is selected so as to satisfy the following conditions. That is, the adhesive strength with the n-pad electrode and the insulating protective film 7 is strong, the adhesive strength with the solder or the conductive paste is maintained for a long time, and the resistance value is low. To satisfy these, the second conductor 11 is formed of one or more layers of metal films. An existing method that satisfies the above characteristics is used as a film forming method.

The second conductor 11 is made of Ti, Cr, Al,
A metal containing Zr, Mo, W, Hf, or Ni as a main component,
Alternatively, it is formed by first depositing a film of an alloy thereof and then depositing a metal mainly containing Au, Ni, or Pt, or an alloy thereof. In the embodiment, Ti is formed first, and then Pt and Au are formed as final layers. In another embodiment, Cr is deposited first, and then Pt and Au are deposited as final layers.

The first conductor 10 and the second conductor 11 are
The same layer configuration is desirable in manufacturing.

In the nitride semiconductor light emitting device of the first embodiment configured as described above, as shown in FIG. 2, for example, a positive electrode 22 and a negative electrode 21 are formed at a predetermined interval. The positive electrode 22 and the first conductor 10
Are mounted so that the negative electrode 21 and the second conductor 11 are opposed to each other, and the opposed conductor and the electrode are joined by solders 31 and 32, respectively, so that a so-called flip-chip mounting is performed.

As described above, the nitride semiconductor light emitting device of the first embodiment mounted by flip chip mounting has the first opening 7
Since the first conductor 10 extending on the insulating protective film 7 outside the b and the second conductor 11 extending on the insulating protective film 7 outside the second opening 7a are formed, as shown in FIG. When flip-chip mounting is performed, the melted solders 31 and 32 are guided outward by the first conductor 10 and the second conductor 11 extending outward, and the first conductor 10 (p pad electrode 5) and the second
The amount of solder between the conductor 11 (the n-electrode 6) can be reduced. Thereby, in the nitride semiconductor light emitting device of the first embodiment, a short circuit between p pad electrode 5 and n electrode 6 can be effectively prevented.

On the other hand, in the conventional nitride semiconductor light emitting device, as shown in FIG. 3, through the first opening 7c and the second opening 7d formed in the insulating protective film 70 covering the semiconductor layer and the electrode. To connect the p pad electrode 5 and the n electrode 6 respectively.
The positive electrode 24 and the negative electrode 23 formed on the mounting substrate 20 are connected to face each other. In the conventional nitride semiconductor light emitting device thus mounted, the solder 3
Reference numerals 3 and 34 protrude almost equally on both sides of the outside and inside (between the p pad electrode 5 and the n electrode 6) of the p pad electrode 5 and the n electrode 6. Therefore, in the conventional nitride semiconductor light emitting device, when the flip chip mounting is performed, the p pad electrode 5 and the n
The amount of solder protruding between the electrodes 6 becomes relatively large, and the p pad electrode 5 and the n electrode 6 may be short-circuited.

Further, in the nitride semiconductor light emitting device of the first embodiment, the inner side surfaces (side surfaces facing each other) of the first conductor 10 and the second conductor 11 are respectively formed by the p pad electrode 5 and the n electrode 6. It is located outside the inner side surfaces (side surfaces facing each other). By doing so, p
Since the distance between the inner side surfaces of the first conductor 10 and the second conductor 11 can be made larger than the distance between the inner side surfaces of the pad electrode 5 and the n-electrode 6, the p-side and n-side surfaces can be more effectively used. Short circuit can be prevented.

In the nitride semiconductor light emitting device of the above embodiment, the p pad electrode 5 and the n electrode 6 which are parallel to each other are formed along two opposing sides of the sapphire substrate 1. The present invention is not limited to this, and the p pad electrode 5 and the n electrode 6 may be formed at one diagonal corner of the sapphire substrate 1.

Further, in the nitride semiconductor light emitting device of the first embodiment, the example in which the n-type nitride semiconductor layer 2 and the p-type nitride semiconductor layer 3 are formed has been described, but the present invention is not limited to this. Instead, an active layer may be further formed between the n-type nitride semiconductor layer 2 and the p-type nitride semiconductor layer 3. Further, each of the n-type nitride semiconductor layer 2 and the p-type nitride semiconductor layer 3 is shown as one semiconductor layer, but the present invention is not limited to this, and the n-type nitride semiconductor layer 2 and the p-type nitride semiconductor
The type nitride semiconductor layer 3 may be composed of a plurality of layers.

(Embodiment 2) Next, the first conductor 1
A nitride semiconductor light emitting device similar to that of the first embodiment is formed except that the 0 'and the second conductor 11' are formed as shown in FIG. That is, the first conductor 10 'and the second conductor 11'
The first conductor 10 'and the second conductor 11' are formed so that the insulating protection film 7 is not completely covered at the periphery of the chip, but is slightly exposed. As in the first embodiment of the present invention, when the first conductor 10 and the second conductor 11 completely cover the insulating protective film 7 at the chip periphery, each chip in a wafer state before being separated by dicing or scribing is used. First conductor 10 which is a metal thin film
And the adjacent chip is connected via the second conductor 11, and the separation operation tends to be difficult. In order to prevent this, the first conductor 10 'and the second conductor 11' are separated from each other at the chip peripheral portion in order to easily separate the chips one by one as in the second embodiment of the present invention. It is desirable to be formed.

[0025]

As described in detail above, the nitride semiconductor light emitting device according to the present invention has a first conductor on the insulating protective film outside the opening on the p electrode, the first conductor being electrically connected to the p electrode. Is formed on the insulating protective film outside the opening on the n-electrode, and the second conductor that is electrically connected to the n-electrode is formed. In addition, the molten solder at the time of flip chip bonding can be guided to the outside, and the protruding of the molten solder between the p electrode and the n electrode can be suppressed. Therefore, the nitride semiconductor light emitting device according to the present invention has
A short circuit between the electrode and the n-electrode can be prevented, and a short circuit between the electrodes can be effectively prevented during manufacturing (during flip-chip bonding).

[Brief description of the drawings]

FIG. 1A is a plan view of a nitride semiconductor light emitting device according to a first embodiment of the present invention, and FIG.
It is sectional drawing about the A 'line.

FIG. 2 is a cross-sectional view when the nitride semiconductor light emitting device according to the first embodiment of the present invention is mounted on a mounting substrate.

FIG. 3 is a cross-sectional view when a conventional nitride semiconductor light emitting device is mounted on a mounting substrate.

FIG. 4A is a plan view of a nitride semiconductor light emitting device according to a second embodiment of the present invention, and FIG.
It is sectional drawing about the A 'line.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Sapphire substrate, 2 ... N-type nitride semiconductor layer, 3 ... P-type nitride semiconductor layer 3, 5 ... P pad electrode, 6 ... N electrode, 7a ... Second opening, 7b ... First opening, 8 ... p-electrode, 10, 10 '... first conductor, 11, 11' ... second conductor.

Claims (4)

[Claims] An n-type nitride semiconductor layer formed on a light-transmitting substrate; an n-electrode and a p-type nitride semiconductor layer provided separately on the n-type nitride semiconductor layer; a p-electrode provided on a part of the p-type nitride semiconductor layer, and an insulating protective film provided so as to cover the semiconductor layers and the electrodes except for openings on the upper surfaces of the n-electrode and the p-electrode. In the nitride semiconductor light emitting device, a first conductor that is electrically connected to the p-electrode is formed on the insulating protective film outside the opening on the p-electrode, and the first conductor on the n-electrode outside the opening. A nitride semiconductor light emitting device, wherein a second conductor that is electrically connected to the n-electrode is formed on an insulating protective film. 2. The semiconductor device according to claim 1, wherein the p-electrode comprises a full-surface electrode formed on substantially the entire surface of the p-type nitride semiconductor layer and a p-pad electrode formed on a part of the full-surface electrode. 2. The nitride semiconductor light emitting device according to claim 1, wherein said opening is formed on said p pad electrode. 3. The nitride semiconductor light emitting device according to claim 2, wherein a distance between said first conductor and said second conductor is larger than a distance between said p pad electrode and said n electrode. 4. The semiconductor device according to claim 1, wherein the first conductor and the second conductor are formed on the insulating protective film other than a peripheral portion of the nitride semiconductor device, and the insulating protective film is exposed in the peripheral portion. Nitride semiconductor light emitting device.