JP2002057373A - Semiconductor light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor light-emitting device where a flip chip light-emitting element is easily mounted and fixed on its mounting surface while the light leaking toward the mounting surface is effectively recovered on a main light take-out surface for improved luminosity. SOLUTION: A flip chip light-emitting device is provided where a transmissive substrate 1 side of a semiconductor light-emitting element A is taken as the main light take-out surface while the surface on the opposite side faces the mounting surface and electrode pads 2a and 3a on an n-side and a p-side are connected together for continuity. A short preventive band is formed on the mounting surface so that conductive bonds 14 which fix the electrode pads 2a and 3a to the mounting surface for continuity, do not contact each other. A reflective film 13 is formed on the surface of the short preventive band, over which the semiconductor light-emitting element A is mounted while the surface of a p-type layer 3 is directly contacted.

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 having a flip-chip type light-emitting element using a GaN-based compound semiconductor emitting blue light, for example, in particular, by effectively utilizing conduction fixation with a conductive adhesive. The present invention relates to a semiconductor light emitting device in which light leaking to a mounting surface side is recovered to improve light emission luminance.

[0002]

2. Description of the Related Art GaN, GaAlN, InGaN and I
In a blue light emitting device using a GaN-based compound semiconductor such as nAlGaN, sapphire is currently most commonly used as a substrate for crystal growth. FIG. 6 is a schematic perspective view of a GaN-based compound semiconductor light emitting device using sapphire as a substrate.

In FIG. 6, an n-type layer 2 and a p-type layer 3 of GaN are sequentially laminated on a sapphire substrate 1, and a p-type layer 3 is formed.
Is etched to form an n-side electrode pad 2a on the surface of the n-type layer 2. Further, a p-side electrode pad 3a is provided on the surface of the p-type layer 3, and in the illustrated example, a p-side translucent electrode 3b is formed in a portion other than the p-side electrode pad 3a.

In such a semiconductor light emitting device, the n-type layer 2
The light from the light emitting layer between the substrate 1 and the p-type layer 3 passes through the p-side light-transmissive electrode 3b in the figure and goes upward, and because the sapphire of the substrate 1 is light-transmissive, And those that go down. By utilizing this fact, a flip-chip type assembly in which conduction is fixed to the lead frame side by bump electrodes as shown in FIG.

In FIG. 7, n-side electrode pads 2a and p
The bump electrodes 51 and 52 are respectively provided on the side electrode pads 3a.
Are formed in advance, and a pair of leads 53,
The bump electrodes 51 and 52 are bonded to the mount portions 53a and 54a of the 54 by a pressure bonding method using ultrasonic waves and heating. In such a flip-chip type assembly, light emission with the upper surface of the substrate 1 as a main light extraction surface in FIG. 7 can be obtained. The components of light that escape from the light-emitting layer to the side and downward from the p-side translucent electrode 3b are collected on the main light extraction surface side by making the surfaces of the mount portions 53a and 54a reflection surfaces by plating or the like. Light emission is possible.

[0006]

However, the lead 5
3, 54 are bifurcated, there is a gap G on the surface facing the p-side translucent electrode 3b, and light passing through this gap G cannot be collected on the main light extraction surface side.

On the other hand, the bump electrodes 51 and 52 also serve as spacers for preventing short circuit when the n-side and p-side electrode pads 2a and 3a are mounted on the mount portions 53a and 54a because of their small thickness. Therefore, the bump electrodes 51 and 52 have a certain thickness, so that the p-side translucent electrode 3
A gap is formed between b and the mounting portions 53a and 54a, and this portion becomes a layer of sealing resin. Therefore, even if the mounting surfaces of the mount portions 53a and 54a are used as reflection surfaces, the mount portions 53a and 54a enter the sealing resin layer through the p-side translucent electrode 3b and enter the mount portion 5a.
Since the light path is reflected by the reflecting surfaces 3a and 54a and re-enters the light path, the light cannot be effectively collected.

Further, in order to prevent the light emitting element from being destroyed by static electricity, it has already been proposed to make an assembly combined with an electrostatic protection element or the like. As shown in FIG. 8, this is a static electricity protection element 61 using a Zener diode.
The light emitting element shown in FIG. 6 is mounted thereon to form a composite element, and the electrostatic protection element 61 is replaced by a lead 62 of a lead frame.
It is mounted on.

The electrostatic protection element 61 uses, for example, an n-type silicon substrate, and has an n-electrode 61c formed on the bottom surface thereof.
The lead 62 is electrically connected to the lead 62, and an n-electrode 61a is formed on the upper surface and a p-electrode 61b is formed corresponding to a p-type semiconductor region formed in a part of the n-type silicon substrate. The p-side electrode pads 3a and p
By bonding the n-side electrode pad 2a to the electrode 61b by the bumps 51 and 52 and conducting it with the opposite polarity, when an overcurrent is applied by a high voltage, a current flows to the electrostatic protection element 61, and the static electricity of the light emitting element Prevent destruction.

When the semiconductor light emitting element is mounted on the electrostatic protection element 61 in this way, the p-side translucent electrode 3b covers the electrostatic protection element 61, so that the electrostatic protection element 6
If the surface 1 is used as a reflection surface, light can be collected on the main light extraction surface side.

However, the bump electrodes 51 and 52 are provided between the surface of the electrostatic protection element 61 and the p-side translucent electrode 3b.
As a result, a gap is formed, so that the air layer or the sealing resin layer in the gap makes it impossible to sufficiently collect light as in the example of FIG.

As described above, when the bump electrodes 51 and 52 are joined to the lead frame side, a gap is formed between the light emitting element and the mounting surface thereof. Tends to decrease. Also, when bonding to the mounting surface, it is necessary to apply pressure vibration using ultrasonic waves or the like or to heat for welding, which may cause damage to the semiconductor laminated film of the light emitting element, The impact on product yield cannot be ignored.

The problem to be solved in the present invention is that a flip-chip type light emitting element can be easily mounted and fixed on its mounting surface, and light leaking in the direction of the mounting surface can be effectively collected on the main light extraction surface side to reduce the emission luminance. An object of the present invention is to provide a semiconductor light emitting device that can be improved.

[0014]

According to the present invention, there is provided a semiconductor light emitting device in which a compound semiconductor is laminated on a light-transmitting substrate and p-side and n-side electrodes are formed on the surface of the laminate, respectively. A semiconductor light emitting device in which the p-side and n-side electrodes are conductively mounted on a mounting surface and the substrate side is a main light extraction surface, wherein the mounting surface has a space between the n-side and p-side electrodes. A short-circuit prevention band is provided as a positional relationship to be removed, and the n-side and p-side electrodes and the conductive connection portion of the mounting surface are joined by a conductive adhesive in respective regions partitioned by the short-circuit prevention band. It is characterized by becoming.

In such a configuration, even when a conductive adhesive is used, the p-side and the n-side are respectively joined to the mounting surface by the short-circuit prevention band interposed between the p-side and the n-side of the semiconductor light emitting device. The conductive adhesive does not come into contact with the conductive adhesive, thereby preventing a short circuit. By appropriately setting the thickness of the conductive adhesive, the surface of the laminated film of the semiconductor light emitting element can be brought closer to the surface of the short-circuit prevention band. The efficiency of light reflection on the light extraction surface side can be increased.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, there is provided a semiconductor light emitting device in which a compound semiconductor is laminated on a light-transmitting substrate and p-side and n-side electrodes are formed on the surface side of the laminated body. An element and a semiconductor light emitting device in which the p-side and n-side electrodes are conductively mounted on a mounting surface and the substrate side is a main light extraction surface, and the mounting surface includes the n-side and p-side electrodes. A short-circuit prevention band is provided as a positional relationship between the n-side and p-side electrodes and the conductive connection portion of the mounting surface, and a conductive adhesive is provided in each region partitioned by the short-circuit prevention band. The short-circuit prevention band has the effect of preventing the conductive adhesive bonding the p-side and the n-side from each other to the mounting surface, thereby preventing a short circuit.

According to a second aspect of the present invention, the surface of the short-circuit prevention band is a reflecting surface for reflecting light from the surface of the compound semiconductor laminated film in the direction of the main light extraction surface. 2. The semiconductor light emitting device according to claim 1, wherein the light exiting from the surface of the laminated film is directly reflected from the reflection surface formed on the surface of the short-circuit prevention band, so that the light exits toward the main light extraction surface. Has the effect of increasing the light collection efficiency.

According to a third aspect of the present invention, there is provided the semiconductor light emitting device according to the second aspect, wherein the reflection surface is formed as a light-reflective film formed on the surface of the short-circuit prevention band. Even if there is no material, it is only necessary to form a reflective film, and it has an effect that it can cope with various types of mounting surfaces.

A specific example of the embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a longitudinal sectional view showing a main part of a semiconductor light emitting device of the present invention, and FIG. 2 is a plan view showing the semiconductor light emitting device excluding a semiconductor light emitting element.

In this embodiment, an LED resin-sealed with a resin also having a lens function in the final step
This is an example of a lamp, and the semiconductor light emitting element is the same as that shown in the example of FIG.

In FIG. 1, the upper ends of a pair of leads 4 and 5 of a bifurcated lead frame conductively fixed to a printed wiring board (not shown) or the like are respectively formed in a semicircular planar shape and the inner peripheral wall thereof is formed. Mount part 4 inclined in a mortar shape
a, 5a are formed, and the semiconductor light emitting element A is conductively fixed across the mount portions 4a, 5a.

The bottom surfaces and the inner peripheral surfaces of the mounting portions 4a and 5a of the leads 4 and 5 are made to have a metallic reflecting surface or a metal reflecting surface, and are formed as a reflecting surface for the light emitted downward and laterally from the semiconductor light emitting element A.

The semiconductor light emitting element A is similar to the example shown in FIG.
A substrate 1 using sapphire, an n-type layer 2 and a p-type layer 3 of GaN, an n-side electrode pad 2a and a p-side electrode pad 3a are provided. Since the sapphire of the substrate 1 is transparent, the light from the light emitting layer between the n-type layer 2 and the p-type layer 3 uses the surface of the substrate 1 (the upper surface in FIG. 1) as the main light extraction surface. Released. In addition, the entire surface of the p-type layer 3 excluding the p-side electrode pad 3a formed by the metal deposition method becomes a light emitting surface.
Light is emitted to 5a. In addition, as shown in the example of FIG. 6, a light-transmitting electrode may be formed on the surface of the p-type layer 3.

An insulating pad 6 is stretched and fixed between the mount portions 4a and 5a as a short-circuit prevention band in the present embodiment, and a reflective film 7 is integrally formed on the surface of the insulating pad 6. The insulating pad 6 is a semiconductor light emitting element A
Is fixed in advance to the surfaces of the mount portions 4a and 5a by a welding method or the like using a resin plate or the like having mechanical strength to withstand the mounting load of the above. The reflection film 7 is insulative. For example, a film in which a silver-white metal film such as Ag, Al, or Pt is covered with an insulation film such as SiO _X or SiN _X can be used. Are laminated.

As shown in FIG. 2, the insulating pad 6 has a planar shape in which a portion where the pads 2a and 3a of the n-side and p-side electrodes of the semiconductor light emitting element A overlap is cut out. The reflection film 7 is preferably formed so as to correspond to the entire surface of the p-type layer 3 except for the p-side electrode pad 3a. No problem.

In contrast to such a lead frame having the insulating pad 6 on which the reflective film 7 is formed between the mount portions 4a and 5a, the semiconductor light emitting element A has the surface of the p-type layer 3 as shown in FIG. It is fixed by a conductive adhesive 8 such as an Ag paste in contact with the reflection film 7. At this time, the conductive adhesive 8 is applied in advance to the surfaces of the mount portions 4a and 5a so as to correspond to the n-side and p-side electrode pads 2a and 3a, and the posture of the semiconductor light emitting device A is determined in FIG. To be mounted.

In the above configuration, the n-side and p-side electrode pads 2a and 3a of the semiconductor light emitting device A are electrically conductive adhesive 8
Thus, the leads 4 and 5 are electrically connected and fixed. In this case, since there is no need to perform ultrasonic pressure bonding or heat welding as when using a bump electrode, the mechanical load on the stacked films such as the n-type layer 2 and the p-type layer 3 can be reduced, and the damage can be reduced. Generation is suppressed. Since the insulating pads 6 are interposed between the conductive adhesives 8 separately applied to the mount portions 4a and 5a, a short circuit due to the outflow of the conductive adhesives 8 may occur. Is prevented.

The surface of the p-type layer 3 is adhered to the reflection film 7 on the surface of the insulating pad 6, so that there is no gap between the surface of the p-type layer 3 serving as a light emitting surface and the reflection film 7. That is,
Since the surface of the p-type layer 3 and the reflective film 7 are in close contact with each other, the surface of the p-type layer 3 becomes almost the reflection surface itself, which is almost the same as the condition in which light from the light emitting layer does not go out of the p-type layer 3. Can be reflected as Therefore, the light emitted from the p-type layer 3 does not have an optical path that returns from the sealing resin layer toward the mount portion as in the related art, so that the reflection efficiency to the main light extraction surface side is increased, and As a result, the light emission luminance is also improved.

FIG. 3 is a longitudinal sectional view of an LED lamp in which a semiconductor light emitting device is combined with an electrostatic protection device together with an electrostatic protection device.

In FIG. 3, a Si diode 10 is conductively mounted as an electrostatic protection element on a mount 9c formed on one of the leads 9a and 9b of the lead frame 9, and a semiconductor light emitting element A is mounted on the Si diode 10. . Then, the wire 11 is bonded between the Si diode 10 and the lead 9 b with a wire 11.
1 is sealed by the epoxy resin 12.

FIG. 4 is a schematic longitudinal sectional view showing a conductive mounting structure of the semiconductor light emitting element A and the Si diode 10, and FIG. 5 is a perspective view showing an outer shape of the surface of the Si diode 10.

The Si diode 10 is an n-type silicon substrate 1
An n-electrode 10b is provided on the bottom surface of Oa, and a p-type impurity is partially implanted from the upper surface to form a p-type semiconductor region 10c. Then, the p-type semiconductor region 10
c, a p-side electrode 10d is provided, and an n-side electrode 10e is formed at a position diagonally away from the p-side electrode 10d.
The wire 11 is bonded to the surface of d.

The n-type silicon substrate 1 of the Si diode 10
0a has two concave portions 10 for joining as shown in FIG.
f, 10g are provided, the space between these recesses 10f, 10g is a partition wall 10h as a short-circuit prevention band in the present embodiment, and a reflective film 13 is integrally bonded to the surface thereof. In the one concave portion 10f, the p-side electrode 10d described above is formed by lamination from the bonding portion of the wire 11, and in the other concave portion 10g, the n-side electrode 10e is located.

In contrast to such a Si diode 10, the semiconductor light emitting element A has an n-side electrode pad 2 as shown in FIG.
a is made to correspond to one recess 10f, and the p-side electrode pad 3a is mounted to correspond to the other recess 10g. Then, each of the n-side electrode pad 2a and the p-side electrode 10d and the p-side electrode pad 3a and the n-side electrode 10e are joined by a conductive adhesive 14 such as an Ag paste in the same manner as in the previous example. At this time, the dimensional relationship of each part is determined so that the surface of the p-type layer 3 is in close contact with the reflective film 13 formed on the upper surface of the partition 10h of the Si diode 10.

As described above, even in a configuration in which a composite element is formed together with the Si diode 10, the surface of the p-type layer 3 is brought into close contact with the reflective film 13 so that light that escapes toward the Si diode 10 is efficiently directed to the main light extraction surface. The light can be reflected, and the emission luminance can be improved. In addition, since the conductive adhesive 14 is applied in the recesses 10f and 10g and is separated from each other by the partition 10h, an assembly that does not cause a mutual short circuit can be realized.

[0037]

According to the first aspect of the present invention, even if a conductive adhesive is used, a short circuit can be prevented by the short prevention band, so that the gap between the semiconductor light emitting element and its mounting surface can be reduced as compared with bonding using a bump electrode. In this case, the assembly can be shortened, and no load such as heat compression is applied, so that the semiconductor laminated film is not damaged and the product yield is improved.

According to the second aspect of the present invention, light that escapes from the surface of the laminated film is directly reflected from the reflection surface formed on the surface of the short-circuit prevention band. Light emission luminance can be increased.

According to the third aspect of the present invention, it is only necessary to form a reflective film even if the mounting surface is made of a material having no light reflectivity. The degree of freedom can be increased.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view showing a main part of a semiconductor light emitting device according to an embodiment of the present invention.

FIG. 2 is a plan view showing the semiconductor light emitting device of FIG. 1 except for a semiconductor light emitting element;

FIG. 3 is a vertical cross-sectional view of an LED lamp including a semiconductor light-emitting element formed into a composite element together with a Si diode for electrostatic protection.

FIG. 4 is a longitudinal sectional view showing a conductive mounting structure of a Si diode and a semiconductor light emitting element in the example of FIG. 3;

FIG. 5 is a schematic perspective view showing the outer shape of a Si diode.

FIG. 6 is a schematic perspective view of a GaN-based compound semiconductor light emitting device.

FIG. 7 is a longitudinal sectional view showing a conventional mounting structure of a semiconductor light emitting element on a lead frame using bump electrodes.

FIG. 8 is a schematic view showing a conventional example in which a semiconductor light emitting element is joined to an electrostatic protection element by a bump electrode to form a composite element.

[Explanation of symbols]

 Reference Signs List 1 substrate 2 n-type layer 2a n-side electrode pad 3 p-type layer 3a p-side electrode pad 3b p-side translucent electrode 4,5 lead 4a, 5a mount 6 insulating pad 7 reflective film 8 conductive adhesive 9 lead frame 9a, 9b Lead 9c Mount 10 Si diode 10a n-type silicon substrate 10b n-electrode 10c p-type semiconductor region 10d p-side electrode 10en n-side electrode 10f, 10g recess 10h partition 11 wire 12 epoxy resin 13 reflective film 14 conductive adhesive

Claims (3)

[Claims] 1. A semiconductor light emitting device comprising: a compound semiconductor layered on a light-transmitting substrate; and a p-side electrode and an n-side electrode formed on the surface of the layered body, respectively; A semiconductor light emitting device having the substrate side as a main light extraction surface by conductively mounting the substrate on a mounting surface, wherein the mounting surface has a short-circuit prevention band as a positional relationship passing between the n-side and p-side electrodes. A semiconductor light-emitting device comprising: an n-side electrode and a p-side electrode; and a conductive connection portion of the mounting surface, which is joined by a conductive adhesive in respective regions defined by the short-circuit prevention band. 2. The surface of the short-circuit prevention band is a reflecting surface for reflecting light from the surface of the compound semiconductor laminated film in the direction of the main light extraction surface, and the surface of the laminated film is brought into close contact with the reflecting surface. The semiconductor light emitting device according to claim 1, wherein: 3. The semiconductor light emitting device according to claim 2, wherein said reflection surface is a light-reflective film formed on a surface of said short-circuit prevention band.