JPH10308537A - Semiconductor light-emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor light-emitting element whose yield and reliability are not lowered due to a wire bonding operation, even when a substrate on which a semiconductor layer is laminated in order to form a light- emitting layer is an insulating substrate, in which the substrate is not charged with static electricity, which is not broken down due to static electricity and whose performance is not lowered. SOLUTION: A light-emitting element chip 1 is composed of an insulating substrate, of a semiconductor laminated part which is laminated so as to form a light-emitting layer on the insulating substrate, of a first electrode (a p-side electrode 28) which is formed so as to be connected to a first-conductivity-type semiconductor layer on the surface side of the semiconductor laminated part, and of a second electrode (an n-side electrode 29) which is formed so as to be connected to a second-conductivity-type semiconductor layer in the semiconductor laminated part. In addition, the rear of the insulating substrate at the light-emitting element chip is bonded onto a conductive member (a first lead 2), and the second electrode is connected directly to a conductive layer by a conductive adhesive 9 via the side face of the insulating substrate.

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 which a semiconductor layer is laminated on an insulating substrate such as a sapphire substrate to form a light emitting layer. More specifically, the present invention relates to a semiconductor light emitting device in which two electrodes are provided on a surface side of a semiconductor layer stacked on an insulating substrate.

[0002]

2. Description of the Related Art For example, a light-emitting lamp using a light-emitting element chip (hereinafter, referred to as an LED chip) 20 that emits blue light has a structure as shown in a sectional view in FIG. The blue LED chip 20 is formed by stacking a gallium nitride (GaN) compound semiconductor on a sapphire substrate 21. For this reason, one electrode cannot be taken out from the back surface of the substrate 21, and the p-side electrode 28 and the n-side electrode 29 of the LED chip 20 die-bonded in the curved portion at the tip of the first lead 11 Protrusion 11a at the tip of the lead 11 and the second lead 1
2 are respectively wire-bonded with gold wires 13. Then, the periphery thereof is covered with a resin that transmits light emitted by the light emitting layer to form the resin package 14, thereby forming a light emitting lamp.

That is, since the substrate of the LED chip 20 is an insulating substrate, it is difficult to provide an electrode on the back side of the substrate, and only by die bonding to the tip of a lead, one electrode can be electrically connected. Can not do. Therefore, both the p-side electrode 28 and the n-side electrode 29 must be electrically connected by a wire such as a gold wire.

[0004]

The electrical connection using a wire such as a gold wire requires skill in wire bonding, and the electrical connection is insufficient or broken due to the bonding strength. And the reliability decreases. for that reason,
In the LED chip having the above-described insulating substrate, when the p-side and the n-side electrodes are wire-bonded from the surface side of the stacked semiconductor layers, the above-described problem is caused as compared with the case of wire bonding of only one electrode. Double.

Further, as described above, when the p-side electrode is electrically connected to the first lead by die bonding to the first lead, an insulating substrate is sandwiched between the p-side electrode and the n-side electrode. Therefore, it becomes a capacitor and cannot discharge static electricity charged before die bonding.
Further, even if the n-side electrode is connected to the first lead, if the insulating substrate is die-bonded with an insulating adhesive, the static electricity charged before the die bonding cannot be released in a floating state of the insulating substrate. Furthermore, when static electricity enters from the outside via the leads, the static electricity tends to accumulate on this insulating substrate. When the accumulation of the static electricity increases, carriers (electrons or holes) move to the semiconductor layer to cause cracks in the crystal structure of the semiconductor, which causes a problem of deteriorating light emission characteristics.

The present invention has been made to solve such a problem. The substrate on which a semiconductor layer is laminated to form a light emitting layer is an insulating substrate, and both the p-side and n-side electrodes are formed of a substrate. Even if it is provided on the side of the semiconductor layer laminated on the surface, it does not cause a decrease in yield and reliability due to wire bonding, and it does not charge the substrate with static electricity. It is an object of the present invention to provide a semiconductor light emitting device that does not cause the light emitting device.

[0007]

A semiconductor light emitting device according to the present invention comprises an insulating substrate, a semiconductor laminated portion on which a semiconductor layer is laminated to form a light emitting layer on the insulating substrate, and a semiconductor laminated portion. A first electrode provided to be electrically connected to the first conductive type semiconductor layer on the front surface side; and a second conductive type semiconductor layer exposed by removing a part of the semiconductor laminated portion by etching. And a second electrode connected to the light emitting element chip, the back surface of the insulating substrate of the light emitting element chip is bonded to a conductive member, and the second electrode is connected to the insulating substrate. Is directly connected to the conductive member by a conductive adhesive.

[0008] With this configuration, since the second electrode is directly connected to the conductive member by the conductive adhesive, the wire bonding, which tends to reduce the reliability, is performed by the first electrode.
On the electrode side only.

The light emitting element chip is die-bonded with a conductive adhesive, and a part of the conductive adhesive is provided so as to be connected to the second electrode via a side surface of the insulating substrate. Since both surfaces of the insulating substrate are at the same potential, the insulating substrate does not act as a capacitor, the charged static electricity is discharged, and the static electricity is not charged thereafter. As a result, the crystal structure of the semiconductor layer is not destroyed by static electricity.

If the semiconductor laminated portion on which the semiconductor layers are laminated to form the light emitting layer is made of a gallium nitride compound semiconductor, a blue semiconductor light emission using a gallium nitride compound semiconductor which is particularly susceptible to static electricity is provided. The reliability of the device can be improved. Here, the gallium nitride-based compound semiconductor refers to a compound of a group III element Ga and a group V element N, or a compound in which a part of the group III element Ga is replaced with another group III element such as Al and In. And / or a semiconductor made of a compound in which part of N of a group V element is substituted with another group V element such as P or As.

If the semiconductor light-emitting element is a lamp-type light-emitting element, the tip of a lead for die-bonding the light-emitting element chip can be the conductive member. In the case of bonding directly to a substrate or in the case of a chip type light emitting element in which a light emitting element chip is mounted on an insulating substrate provided with electrodes at both ends, a wiring pattern (electrode provided on an insulating substrate) (Including patterns) can be used as the conductive member.

[0012]

Next, a semiconductor light emitting device of the present invention will be described with reference to the drawings.

LE used in the semiconductor light emitting device of the present invention
As shown in FIG. 2, a cross-sectional view of an example of the D chip 1 includes an insulating substrate 21 made of sapphire or the like, and a semiconductor laminate in which a semiconductor layer is formed on the insulating substrate 21 to form a light emitting layer. A portion 26, a p-side electrode 28 (first electrode) electrically connected to a p-type layer 25 (first conductivity type semiconductor layer) on the surface side of the semiconductor laminated portion 26, and a semiconductor laminated portion 26. And an n-side electrode 29 (second electrode) provided to be electrically connected to the n-type layer 23 (second conductivity type semiconductor layer) that is partially removed by etching. Then, as shown in FIG. 1, a cross-sectional explanatory view of one embodiment of the semiconductor light emitting device of the present invention, the back surface of the insulating substrate 21 of the LED chip 1 is adhered by the adhesive 4 to form the first lead 2. Is die-bonded to the tip of the Then, the tip of the first lead 2 (conductive member)
And the n-side electrode 29 are electrically connected by the conductive adhesive 9.

As shown in FIG. 2, for example, the LED chip 1 has a low-temperature buffer layer made of, for example, GaN and an n-type GaN and / or AlGaN-based compound semiconductor (made of a cladding layer) on an insulating substrate 21 made of sapphire. The n-type layer 23 having a laminated structure of 1 to 5 means that the ratio of Al and Ga can be variously changed.
A material whose band gap energy is smaller than that of the cladding layer by about μm, for example, an InGaN-based (In
The active layer 24 made of a compound semiconductor is in the range of 0.05 to 0.3.
The thickness of the p-type layer (cladding layer) 25 made of p-type GaN and / or AlGaN-based compound semiconductor is about 0.2 μm.
The semiconductor laminated portion 26 is formed by laminating about 1 μm each. Then, the p-side electrode 28 is electrically connected to the p-type layer 25 via a current diffusion metal layer made of an alloy layer of Ni and Au (not shown) provided on the surface thereof, so that the p-side electrode 28 is formed of a laminate of Ti and Au, for example. The n-side electrode 29 is provided by a structure, and is electrically connected to the n-type layer 23 in which a part of the laminated semiconductor layer is etched and exposed, so that the n-side electrode 29 is provided by, for example, an alloy layer of Ti and Al.
An LED chip 1 is formed.

As shown in FIG. 1, the LED chip 1 is die-bonded to the curved portion of the first lead 2 by using, for example, an epoxy-based adhesive 4 and the insulating substrate 21 on the n-side electrode 29 side. A conductive adhesive 9 such as Ag paste is provided so that the n-side electrode 29 and the first lead 2 are electrically connected via the side surface. The electrical connection by the conductive adhesive 9 is formed by applying a conductive adhesive such as a silver paste so as to flow along the side surface of the insulating substrate 21 from the n-side electrode 29 and drying. As shown in FIG. 2, the upper layer of the insulating substrate 21 of the LED chip 1 is only the n-type layer 23 including the buffer layer.
Since the n-side electrode 29 is provided on the n-type layer 23,
Even if the conductive adhesive 9 is provided through the side surface, there is no danger of short-circuit with the p-type layer. As a result, the n-side electrode 29
And the first lead 2 are electrically connected without wire bonding. Only the p-side electrode 28 is electrically connected to the second lead 3 by wire bonding such as the gold wire 5. And the surrounding is L
The package 6 is formed by molding with an epoxy resin or the like that transmits light emitted by the ED chip 1, thereby forming a light emitting lamp.
The first and second leads 2 and 3 are made of, for example, Al.
And the like.

According to the present invention, as described above, the substrate 21 on which the semiconductor laminated portion 26 forming the light emitting portion is provided is an insulating substrate, and both the p-side electrode 28 and the n-side electrode 29 are laminated. Even in the case of a semiconductor light emitting element provided on the surface side of the semiconductor layer, one n-side electrode 29 is directly electrically connected to the LED chip 1 via the side surface of the LED chip 1 by the conductive adhesive 9. There is no need for bonding. As a result, as in the case of an LED chip in which a semiconductor substrate is used as a substrate and one electrode is provided on the back surface, wire bonding only needs to be performed with one electrode, which causes an increase in defects due to wire bonding and a decrease in reliability. Nothing.

In the above-described example, an epoxy-based insulating adhesive is used as the adhesive 4 for die-bonding the LED chip 1, but a conductive adhesive such as an Ag paste can be used as the adhesive. In this case, a large amount of the adhesive 4 to be applied for die bonding the LED chip 1 is applied on the n-side electrode 29 side, and the LED chip 1 is die-bonded, so that the adhesive 4
Crawling along the insulating substrate of the chip 1 and n-side electrode 2
A conductive adhesive 9 for connecting the first lead 9 to the first lead 2 can be provided at the same time. With this configuration, the n-side electrode 29 and the first lead 2 can be electrically connected with a small number of steps, and the n-type layer covering the upper surface of the insulating substrate 21 (see FIG. 2A). And lower surface (see FIG. 2B)
(Electrically conductive) 4 covering the substrate is electrically connected and at the same potential, so that the carrier is not charged on the insulating substrate 21 and a capacitor is not formed. Therefore, even if static electricity enters through the leads 2 and 3 led out, the insulating substrate 21 is not charged. As a result, static electricity does not accumulate and flows toward the semiconductor layer to degrade the crystal structure, and high characteristics can be maintained without deteriorating light emission characteristics, thereby improving reliability.

Further, in the above-described example, the LED chip 1 is an example of a light-emitting lamp which is bonded to the tip of a lead and covered with a resin. However, as shown in FIG. The same applies to the case of forming a wiring pattern on a printed circuit board. That is, even when the wiring patterns 8a and 8b are formed on the surface of the insulating substrate 7 and the LED chip 1 is die-bonded to the surface, the LED chip 1 is die-bonded to one wiring pattern 8a by the adhesive 4 and The n-side electrode 29 electrically connected to the n-type layer laminated on the surface of the one insulating substrate is provided with the one wiring pattern 8.
The conductive adhesive 9 such as Ag paste is provided through the side surface of the insulating substrate 21 of the LED chip 1 so that the n-side electrode 29 is connected to one wiring without wire bonding. It is electrically connected to the pattern 8a. The other p-side electrode 28 is connected to another wiring pattern 8b by wire bonding such as a gold wire. Also in this case, since a conductive adhesive is used for the adhesive 4, both surfaces of the insulating substrate 21 of the LED chip 1 are held at the same potential, so that static electricity may be charged via the insulating substrate 21. Absent. As a result, even with a semiconductor light emitting device directly die-bonded on a printed circuit board,
The number of steps of the wire bonding can be reduced, and a highly reliable semiconductor light emitting device maintaining high light emitting characteristics as described above can be obtained. The same applies to a chip type light emitting element in which terminal electrodes (electrode patterns) are provided at both ends of an insulating substrate such as a ceramic substrate instead of a printed substrate, and the LED chip 1 is mounted on one of them.

In each of the above-described examples, the LED chip has a double hetero junction structure. However, the LED chip does not have to have a double hetero junction structure but may have a normal pn junction structure. Also, the structure of the present invention can be similarly applied to a semiconductor light emitting element having a structure in which a semiconductor layer is stacked on an insulating substrate even if it is not a gallium nitride compound semiconductor.

[0020]

According to the present invention, it is not necessary to increase the number of wire bondings even in a semiconductor light emitting device in which a semiconductor layer is stacked on an insulating substrate and two electrodes are provided on one surface side. Therefore, the yield and the reliability are not reduced.

Further, the back surface of the insulating substrate of the LED chip is die-bonded with a conductive adhesive, and is electrically connected to the electrode of the upper semiconductor layer, so that static electricity is charged on the insulating substrate of the LED chip. Therefore, it does not destroy the element by itself. Therefore, even in a semiconductor light emitting device using an insulating substrate, the light emitting characteristics can be maintained at a high level, and a highly reliable semiconductor light emitting device can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory sectional view of one embodiment of a semiconductor light emitting device of the present invention.

FIG. 2 is an explanatory sectional view of an example of the LED chip of FIG. 1;

FIG. 3 is an explanatory sectional view of another embodiment of the semiconductor light emitting device of the present invention.

FIG. 4 is an explanatory diagram of an example of a conventional light emitting lamp using an LED chip having an insulating substrate.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 LED chip 2 first lead 3 second lead 9 conductive adhesive 21 insulating substrate 23 n-type layer 25 p-type layer 26 semiconductor lamination portion 28 p-side electrode 29 n-side electrode

Claims (4)

[Claims] An electrical connection is made between an insulating substrate, a semiconductor laminated portion on which a semiconductor layer is laminated to form a light emitting layer on the insulating substrate, and a first conductivity type semiconductor layer on the surface side of the semiconductor laminated portion. A first electrode provided by being electrically connected to the first electrode and a second electrode provided by being electrically connected to a second conductive type semiconductor layer in which a part of the semiconductor laminated portion is removed by etching and exposed. A light emitting element chip is formed, the back surface of the insulating substrate of the light emitting element chip is bonded on a conductive member, and the second electrode is directly connected to the conductive substrate by a conductive adhesive through a side surface of the insulating substrate. Semiconductor light-emitting element connected to a conductive member. 2. The light emitting element chip is die-bonded with a conductive adhesive, and a part of the conductive adhesive is provided so as to be connected to the second electrode via a side surface of the insulating substrate. The semiconductor light-emitting device according to claim 1. 3. The semiconductor light emitting device according to claim 1, wherein the semiconductor laminated portion on which the semiconductor layer is laminated to form the light emitting layer is made of a gallium nitride compound semiconductor. 4. The conductive member is a wiring pattern provided on an end portion of a lead for die-bonding a light emitting element chip or on an insulating substrate.
The semiconductor light-emitting device according to claim 1.