JPH11298041A - Group iii nitride semiconductor light-emitting element and light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve dielectrical breakdown strength with respect to forward and reverse electrostatic voltage. SOLUTION: With a lead frame 402 insert-molded, a frame body 400, wherein a first and second chambers 404 and 406 are constituted with the lead frame 402 exposed, is provided. At the first chamber 404, each chip of a blue light- emitting diode 100, a green light-emitting diode 100G, and a red light-emitting diode 100R is die-bonded, and, at the second chamber 406, the exposed lead frame is provided with Zener diodes 300B and 300G. The Zener diodes 300B and 300G are connected in parallel to respective diodes, connection being made with such polarity as Zener breakdown occurs at a voltage of at least operation voltage in the forward direction of each diode. Thus, an overcurrent is bypassed by Zener breakdown for an overcurrent in forward direction, while as a normal forward diode the excessive voltage is bypassed in reverse direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting device using a group III nitride semiconductor with improved forward and reverse electrostatic withstand voltages and a light source device using the device.

[0002]

2. Description of the Related Art Conventionally, as a group III nitride semiconductor light emitting device,
In _1-X Ga _X N / GaN MQW light emitting layer is p-type AlGaN
Of a double hetero structure sandwiched between a p layer made of GaN and an n layer made of GaN is known. This light emitting element can emit light in a range from green to blue by changing the composition ratio of indium in the light emitting layer. For this reason, utilization as a color light emitting element and a color information reading light source is expected.

[0003]

However, the light emitting device made of the group III nitride semiconductor having the above structure has a problem that the withstand voltage in the forward and reverse directions against static electricity is low.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to improve the dielectric breakdown resistance against static electricity.

[0005]

Means for Solving the Problems and Effects of the Invention
In a light-emitting element having a light-emitting portion including a p-layer made of a Group III nitride semiconductor, a p-electrode for the p-layer, an n-layer, and an n-electrode for the n-layer,
a constant voltage diode that conducts at a constant voltage with respect to a forward voltage equal to or greater than a forward operating voltage between the p electrode and the n electrode; a forward voltage equal to or greater than the forward operating voltage between the p electrode and the n electrode; and ,
A bidirectional constant-voltage diode that conducts at a constant voltage with respect to a reverse voltage, and a compensating element for a static voltage, which is made of at least one of capacitors, are connected.

[0006] By the action of the compensating element, destruction by static electricity applied to the light emitting portion in the forward and reverse directions can be prevented. According to the second and third aspects of the present invention, the compensating element and the light-emitting portion are formed on separate substrates, and the connection between the two is made by using leads. It was done. Since the light emitting section and the compensating element can be manufactured separately and the element can be formed by integrating them, an optimum manufacturing process can be obtained. When the compensating element and the light emitting unit are sealed with a resin in common, the compensating element can be waterproofed and protected against mechanical external force.

According to the fourth and fifth aspects of the present invention, since the compensating element and the light emitting section are formed on the same substrate, the compensating element can be manufactured in the light emitting section layer forming step, and the manufacturing is simplified. You. According to the fifth aspect of the present invention, the compensating element is laminated on the light emitting section. Since the compensating element can be formed following the step of forming the light emitting section, the manufacturing is simplified.

The inventions of claims 6, 7 and 8 relate to a light source device having a plurality of light emitting elements mounted thereon. The invention of claim 6 provides a lead frame, a resin frame having a room in which the lead frame is insert-molded and the lead frame is partially exposed, and a lead frame in the room. The light emitting element according to any one of the above, wherein at least a light emitting element that emits blue light and a light emitting element that emits green light are provided.

According to a seventh aspect of the present invention, the compensating element and the light emitting portion are separate substrates, and the lead frame and the first and second chambers in which the lead frame is insert-molded and the lead frame is partially exposed are formed. And at least a light emitting element emitting blue light or a light emitting element emitting green light are disposed on the lead frame of the first room and the compensating element is disposed on the lead frame of the second room. It is characterized by having been established.

[0010] With these configurations, it is possible to selectively or at least mix blue and / or green light among three primary colors of light from one light source device.

According to the invention of claim 8, the light emitting element which emits red light is further disposed on a lead frame of the room.
Thereby, three primary colors of light can be obtained and can be used for a light source of a color display and a color image scanner.

In a ninth aspect of the present invention, a transparent resin is sealed in the room in which the light emitting element is mounted after the light emitting element is mounted. With this configuration, the light source device can be easily manufactured, and a light source with good confidentiality that can output light can be obtained.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] FIG. 1 is a schematic sectional view of a light emitting diode 100 which is a light emitting element formed of a GaN-based compound semiconductor formed on a sapphire substrate 11. Aluminum nitride (A
1N), a buffer layer 12 having a thickness of about 25 nm is provided.
On top of this, a silicon (Si) -doped GaN film thickness of about 4.0
A high carrier concentration n ⁺ layer 13 of μm is formed. On this high carrier concentration n ⁺ layer 13, an Si-doped n-type GaN
A cladding layer 14 of about 0.5 μm in thickness is formed. Then, a GaN film having a thickness of about 35
The light emitting layer 15 has a multiple quantum well structure (MQW) in which barrier layers 151 made of Ga _0.8 In _0.2 N and a well layer 152 made of Ga _0.8 In _0.2 N having a thickness of about 35 ° are alternately stacked. Barrier layer 1
Reference numeral 51 indicates six layers, and well layer 152 includes five layers. On the light emitting layer 15, a cladding layer 16 of p-type Al _0.15 Ga _0.85 N with a thickness of about 50 nm is formed. Further, a contact layer 1 of p-type GaN having a thickness of about 100 nm is formed on the cladding layer 16.
7 are formed.

A translucent p-electrode 18A is formed on the contact layer 17 by metal deposition, and an n-electrode 18B is formed on the n ⁺ layer 13. The translucent p-electrode 18A is made of cobalt (Co) having a thickness of about 15
And gold (Au) having a thickness of about 60 ° bonded to Co. The n-electrode 18B is made of vanadium (V) having a thickness of about 200 °,
It is made of aluminum (Al) or Al alloy having a thickness of about 1.8 μm. Co or Ni is partially applied on the p-electrode 18A.
An electrode pad 20 made of Au, Al, or an alloy thereof and having a thickness of about 1.5 μm is formed. On the back surface of the substrate 11, a metal layer 10 of aluminum (Al) having a thickness of about 200 nm is formed.

Next, a method for manufacturing the light emitting diode 100 will be described. The light emitting diode 100 was manufactured by vapor phase growth by metal organic chemical vapor deposition (hereinafter abbreviated as “MOVPE”). The gas used was ammonia
(NH ₃ ), carrier gas (H ₂ , N ₂ ), trimethylgallium (G
a (CH ₃ ) ₃ ) (hereinafter referred to as “TMG”), trimethylaluminum (Al (CH ₃ ) ₃ ) (hereinafter referred to as “TMA”), trimethylindium (In (CH ₃ ) ₃ ) (hereinafter referred to as “TMI”) ), Silane (S
iH ₄₎ and cyclopentadienyl magnesium _{(Mg (C 5 H 5)} 2)
(Hereinafter referred to as “CP ₂ Mg”). First, a single crystal substrate 1 having an a-plane as a main surface cleaned by organic cleaning and heat treatment
1 is mounted on the susceptor placed in the reaction chamber of the MOVPE apparatus. Next, the substrate 11 was baked at a temperature of 1100 ° C. while flowing H ₂ into the reaction chamber at normal pressure. Next, the temperature of the substrate 11 is set to 40
0 ° C, supply H ₂ , NH ₃ and TMA to supply AlN
Was formed to a thickness of about 25 nm.

Next, the temperature of the substrate 11 is maintained at 1150 ° C.
Supplying H ₂ , NH ₃ , TMG and silane, the film thickness is about 4.0 μm,
High carrier concentration n composed of GaN with electron concentration of 2 × 10 ¹⁸ / cm ^3
+ Layer 13 was formed. Next, the temperature of the substrate 11 is maintained at 1150 ° C., and N ₂ or H ₂ , NH ₃ , TMG, TMA and silane are supplied to form a GaN film having a thickness of about 0.5 μm and an electron concentration of 1 × 10 ¹⁸ / cm ³ . Was formed. The above cladding layer 1
After the formation of No. 4, N ₂ or H ₂ , NH ₃ and TMG were supplied to form a barrier layer 151 of GaN having a thickness of about 35 °. Next, N ₂ or H ₂ , NH ₃ , TMG and TMI were supplied to form a well layer 152 of Ga _0.8 In _0.2 N having a thickness of about 35 °. Furthermore, the barrier layer 151 and the well layer 152 were formed under the same conditions for four periods, and the barrier layer 151 made of GaN was formed thereon. Thus, the light emitting layer 15 having the MQW structure having five periods was formed.

Next, the temperature of the substrate 11 is maintained at 1100 ° C.
Supplying N ₂ or H ₂ , NH ₃ , TMG, TMA and CP ₂ Mg, a film thickness of about 50 nm, p-type Al _0.15 Ga doped with magnesium (Mg)
_A cladding layer 16 of _0.85 N was formed. Next, the temperature of the substrate 11 is maintained at 1100 ° C., and N ₂ or H ₂ , NH ₃ , TMG and CP ₂ Mg are supplied, and the p-type film having a thickness of about 100 nm and Mg
A contact layer 17 made of type GaN was formed. Next, an etching mask is formed on the contact layer 17, the mask in a predetermined region is removed, and the contact layer 17, the cladding layer 16, the light emitting layer 15, the cladding layer 14, and the n ⁺ A part of the layer 13 is etched by reactive ion etching using a gas containing chlorine, and n ⁺
The surface of layer 13 was exposed. Next, an n-electrode 18B for the n ⁺ layer 13, a translucent p-electrode 18A for the contact layer 17, and an electrode pad 20 were formed by photolithography.

The light emitting diode 100 formed as described above is mounted on a flat portion 203 above the lead 203, as shown in FIG.
1 is connected by a wire 204, and the electrode pad 20 and the lead 202 are connected by a wire 205, and then resin-molded to form a lens 206. On the other hand, the anode 301 of the Zener diode 300 constituting the compensating element is connected to the lead 201, and the cathode 302 of the Zener diode 300 is connected to the lead 202.

As a result, a static voltage higher than the forward operating voltage (about 3.5 V) of the light emitting diode 100 is applied between the leads 202 and 201 in the forward direction (the lead 202 is at a positive potential with respect to 201). In this case, the Zener diode 300 breaks down, and the excess current due to the static voltage flows through the Zener diode 300.
The light emitting diode 100 is protected from dielectric breakdown due to static voltage. When a static voltage is applied between the leads 202 and 201 in a direction opposite to the operating voltage of the light emitting diode 100, excess current flows in the zener diode 300 as a normal diode in the forward direction. The light emitting diode 100 will be protected from high reverse voltage.

Thus, between the leads 202 and 201,
Even when a high static voltage is applied in the forward and reverse directions, current flows through the Zener diode 300, and the light emitting diode 100 is protected from dielectric breakdown due to the static voltage.

[Second Embodiment] In this embodiment, as shown in FIG. 3, a bidirectional Zener diode 310 is resin-molded together with the light-emitting diode 100 and incorporated in a lens 206. Water resistance and protection from external mechanical forces of the Zener diode 310 are achieved. When a bidirectional Zener diode is used as a compensation element, Zener breakdown occurs with respect to forward and reverse static voltages, and the bidirectional operating resistance becomes extremely small. Reliable protection is achieved.

Third Embodiment This embodiment is an example in which a Zener diode 330 is formed on the contact layer 17 of the light emitting diode 120 as shown in FIG. As described above, the layers from the buffer layer 2 to the contact layer 17 are formed. Thereafter, in order to form the Zener diode 330, the first layer 333 made of n-type GaN and the second layer 334 made of p-type GaN are formed uniformly.

Then, by the same steps as in the first embodiment,
After etching, the p-electrode 18 of the light emitting diode 120
A, the electrode pad 20, the n-electrode 18B, the p-electrode layer 331 and the n-electrode layer 332 of the Zener diode 330 are formed. The light emitting element thus formed is attached to the flat portion 203 of the lead 201 as shown in FIG. The electrode pad 20 of the light emitting diode 120 is electrically connected to the n-electrode layer 332 (cathode) of the Zener diode 330 by the wire 220 and is also electrically connected to the lead 202 by the wire 221. Similarly, the n-electrode 18B of the light emitting diode 120 is electrically connected to the lead 201 by a wire 222, and the zener diode 33
0 p-electrode layer 331 is connected to lead 201 by wire 223.
Is electrically connected to

As a result, the Zener diode 330 is connected in parallel to the light emitting diode 120, and the same operation and effect as those of the first embodiment can be obtained.

In the first to third embodiments,
In the forward and reverse directions to the light emitting diodes 100 and 120,
500V static electricity was applied, but no dielectric breakdown was observed.

Fourth Embodiment In this embodiment, two types of blue light emission and green light emission were manufactured for the light emitting diode (chip) 100 made of the group III nitride semiconductor described in the first embodiment. By increasing the indium composition ratio of the light emitting layer 15, a green light emitting diode chip can be obtained. The red light emitting diode (chip) can be obtained from an InGaAlP-based compound semiconductor. This blue light emitting diode 1
00B, the green light emitting diode 100G, and the red light emitting diode 100R are arranged in one resin frame 400.

As shown in FIGS. 5 and 6, a resin frame 400 is formed by insert molding of the lead frame 402. The resin frame 400 has a recess from the upper part of the drawing, and the first chamber 40 in which the lower lead frame 402 is exposed.
4 and a second room 406 are formed. Each chip of the blue light emitting diode 100B, the green light emitting diode 100G, and the red light emitting diode 100R is die-bonded in the first room 404. The lead 408 is a common terminal, and the n-electrode of each diode chip is wire-bonded. The lead 410 is a blue light emitting diode 1
00B is an anode terminal of which the p electrode is wire-bonded. Similarly, the lead 412 is an anode terminal of the green light emitting diode 100G, and its p electrode is wire-bonded. The lead 414 is an anode terminal of the red light emitting diode 100R, and its p electrode is wire-bonded. The lead 416 is a lead for shielding potential.

In the second room 406, Zener diodes 300B and 300G are provided on an exposed lead frame. The anodes (p-electrodes) of the Zener diodes 300B and 300G are die-bonded to the leads 408, and the cathodes (n-electrodes) of the anodes are the leads 410 and 300G.
412 are respectively wire-bonded. The connection relationship between each light emitting diode and each Zener diode is the same as in FIG. Note that a Zener diode is not connected to the red light emitting diode 300R, but this is the case with an InGaAlP-based compound semiconductor.
This is because, unlike the group nitride semiconductor, there is a sufficient electrostatic breakdown voltage in both the forward and reverse directions.

As described above, after connecting each light emitting diode chip and the Zener diode chip on the lead frame, the first room 404 and the second room 406 are filled with the transparent resin. Thereby, the three primary colors of blue, green, and red can be selectively obtained from the surface of the first room 404, or any mixed color light thereof can be obtained. Such a light source device can be used as a light source of a color image scanner.

In any of the above embodiments, the Zener diode may be a bidirectional Zener diode. That is, an element in which individual zener diodes are connected in series in the opposite direction to each other, or a single bidirectional zener diode in which layers of opposite conductivity types such as pnp and npn are stacked may be used. . Instead of the Zener diode, an avalanche diode which is a unidirectional and bidirectional constant voltage diode may be used. Further, a lossy capacitor may be used. For example, in the third embodiment, to make the Zener diode 330 bidirectional, the n-type first layer 333 and the p-type second layer 33 are used.
4, and further, an n-type third layer is stacked on the p-type second layer to form an npn structure. Thereby, a bidirectional Zener diode can be formed on the contact layer 17. In the third embodiment, when a capacitor is used as a compensating element, a p-electrode 18A is uniformly formed on the contact layer 17, and a Si electrode is formed on the p-electrode 18A.
An insulating film made of O ₂ may be formed, and a metal electrode may be formed thereon. Furthermore, in the third embodiment, the contact layer 17
Although the Zener diode is formed on the sapphire substrate 11, a unidirectional or bidirectional Zener diode may be formed in a section different from the light emitting diode 120 on the sapphire substrate 11.

In the above embodiment, a double hetero junction structure is used, but a single hetero junction structure may be used.
Further, although the light emitting layer 15 is made of MQW, it may be made of SQW. Furthermore, in the above embodiment, the example of the light emitting diode is shown.
A laser diode can be similarly configured.
In the third embodiment, the Zener diode 3
Reference numeral 30 uses a group III nitride semiconductor, but other substances may be used.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a configuration of a light emitting diode according to a first specific example of the present invention.

FIG. 2 is a configuration diagram showing a mechanism of the light emitting diode according to the first embodiment.

FIG. 3 is a configuration diagram showing a mechanism of a light emitting diode according to a second embodiment.

FIG. 4 is a sectional view showing a layer structure of a light emitting diode according to a third embodiment.

FIG. 5 is a plan view showing a mechanism of a light source device according to a fourth embodiment.

FIG. 6 is a perspective view showing a configuration of a light source device according to a fourth embodiment.

[Explanation of symbols]

100, 120: Light-emitting diode 10: Metal layer 11: Sapphire substrate 12: Buffer layer 13: High carrier concentration n ⁺ layer 14, 16: Cladding layer 15: Light-emitting layer 17: Contact layer 18A: P electrode 18B: N electrode 20 Electrode pads 300, 310, 330, 300B, 300G Zener diode 331 p electrode layer 332 n electrode layer 201, 202 Leads 220, 221, 222, 223 Wire 400 Resin frame 402 Lead frame 404 One room 406: Second room 408, 410, 412, 414, 416: Lead 100B, 100G, 100R: Light emitting diode

Claims (9)

[Claims] 1. A light-emitting device having a light-emitting portion comprising a p-layer made of a Group III nitride semiconductor, a p-electrode for the p-layer, an n-layer and an n-electrode for the n-layer, wherein the p-electrode and the n-electrode Between the p electrode and the n
A constant-voltage diode that conducts at a constant voltage with respect to a forward voltage equal to or higher than a forward operating voltage between the electrodes, the p-electrode and the n-electrode;
A forward voltage equal to or higher than a forward operating voltage between the electrodes and a bidirectional constant-voltage diode that conducts at a constant voltage with respect to a reverse voltage; and a compensating element for static electricity comprising at least one of capacitors. A group III nitride semiconductor light emitting device characterized by being connected. 2. The method according to claim 1, wherein the compensating element is formed on a substrate different from the substrate on which the light emitting section is formed, and electrical connection between the light emitting section and the compensating element is performed by leads. The group III nitride semiconductor light emitting device according to claim 1, wherein 3. The compensating element is formed on a substrate different from the substrate on which the light emitting section is formed, and an electrical connection between the light emitting section and the compensating element is made by a lead. 3. The group III nitride semiconductor light emitting device according to claim 2, wherein the compensating element is sealed with a resin. 4. The group III nitride semiconductor light emitting device according to claim 1, wherein said compensating element is formed on the same substrate as the substrate on which said light emitting section is formed. 5. The group III nitride semiconductor light emitting device according to claim 4, wherein said compensating element is formed on said p layer of said light emitting section. 6. A lead frame, a resin frame having a room in which the lead frame is insert-molded and the lead frame is partially exposed, and a lead frame in the room,
The light source device according to claim 1, wherein at least a light emitting device that emits blue light or a light emitting device that emits green light is provided. 7. A lead frame, and a first frame formed by insert molding the lead frame and partially exposing the lead frame.
The light emitting device according to claim 2, wherein at least a light emitting device that emits blue light and a light emitting device that emits green light are provided on a resin frame having a room and a second room, and a lead frame of the first room. And a compensating element is provided on the lead frame of the second room. 8. The light source device according to claim 6, wherein a light emitting element that emits red light is further disposed on a lead frame of the room. 9. The room in which the light emitting element is mounted,
The light source device according to any one of claims 6 to 8, wherein a transparent resin is sealed after mounting the light emitting element.