JP2000174348A - Semiconductor light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a semiconductor light-emitting device wherein a light- emitting element can be stably mounted on a submount without inclination, and excellent light emission luminance and high reliability can be maintained. SOLUTION: This light-emitting device is provided with a light-emitting element 1, wherein a P electrode 4 and N electrodes 3a, 3b are formed on the surface of compound semiconductor laminated on an insulating and light transmitting substrate 1a, and a submount 2 electrically continuously mounting the light-emitting element 1 in the attitude that the substrate 1a faces toward the light-emitting direction and the compound semiconductor surface faces toward the mounting surface side. The total number of the P electrode 4 and the N electrodes 3a, 3b is made at least three. A base bottom of a polygon surrounded by segments connecting the electrodes is formed, and the light- emitting element 1 is mounted stably on the submount 2.

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 used for an optical device such as a light-emitting diode or a laser diode, and more particularly, to mounting a light-emitting element on a submount with its electrode forming surface facing down. The present invention relates to a semiconductor light emitting device.

[0002]

2. Description of the Related Art Semiconductor light-emitting devices in which compound semiconductors are stacked on a substrate are rapidly increasing in luminance, and are particularly developed in fields such as blue and green light-emitting diodes and blue-violet laser diodes using GaN-based compound semiconductors. Is remarkable.

[0003] In the manufacture of a blue light-emitting blue diode using a GaN-based compound semiconductor, a light-transmissive and insulating sapphire is currently the most suitable material as a substrate for growing a compound semiconductor thin film layer. It is commonly used. When this sapphire is used as a substrate, the electrode cannot be taken out from the substrate side due to its insulating property. Therefore, unlike a light emitting element using a compound semiconductor such as GaAs or GaP other than a GaN-based compound semiconductor, p
And n electrodes are formed. For example, an n-type layer of GaN is laminated on a sapphire substrate, and GaN is
Of the p-type layer, and the p-type layer is removed by etching deeper than the active layer in the pn junction region at the boundary between the two layers, whereby an n-side electrode and a p-type electrode are formed on the exposed surface of the n-type layer. It has been established as one manufacturing method that a p-side electrode is formed on the surface of each layer by a metal vapor deposition method.

A light emitting device using such an insulating sapphire substrate can be mounted on a lead frame mounting surface, similarly to a compound semiconductor light emitting device such as GaAs or GaP. In other words, the surface of the compound semiconductor layer, that is, the side on which the p-side and n-side electrodes are formed is used as a light-emitting surface, and the substrate is mounted on the mounting surface. What is necessary is just to bond.

However, when conducting by wire bonding, it is necessary to form a certain amount of loop on the wire in order to prevent disconnection and maintain the bonding strength between the electrode and the lead. For this reason, the bulk becomes large corresponding to the bulk of the loop, which ultimately affects the thickness reduction of a product to be packaged by resin sealing.

On the other hand, in a light emitting device using a GaN-based compound semiconductor and a sapphire substrate, in which electrodes cannot be provided on the substrate side, by using a submount effectively, a reduction in light emission luminance and a reduction in thickness can be achieved. Various assemblies have already been proposed. This is a composite element of a sub-mount and a light-emitting element by dicing a chip formed by forming an electrode pattern on a pattern of a light-emitting element in a wafer state, mounting the chip on a sub-mount wafer, and then dicing. It is said that.

[0007] If a composite element is formed in this manner, the thickness can be reduced particularly in the thickness direction because wire bonding is not included. In addition, the submount can be multifunctional as an element for protecting static electricity, or a substrate facing the light emitting surface side. In addition to the light emission from the surface, the electrode facing the submount can be used as a reflection surface to reflect light from the active layer to the light emission surface side to increase the brightness.

As described above, in the case of an assembly in which a light emitting element is combined with a submount, improvement in chip size and improvement in luminous efficiency can be improved. Therefore,
Compared to the so-called face-up type mounting where the board side, which is currently the mainstream, is mounted on the mounting surface,
The same function and light emission performance can be obtained.

[0009]

However, in the case of a composite device with a submount, only two electrodes, p-side and n-side, are formed on the surface of the semiconductor layer.
There is a problem in mounting stability of the light emitting element. In other words, even if the electrodes are electrically connected to the electrodes on the submount by the bump electrodes, the light emitting elements are only supported at two points with respect to the submount, and the stability and the bonding strength after mounting are poor.

If the mounting stability of the light emitting element with respect to the submount is poor, the light emitting element may be inclined on the submount. When such inclination of the light emitting element occurs, the directivity in the light emitting direction becomes poor, and a significant decrease in luminance is inevitable. Further, if the inclination of the light emitting element is large, for example, the semiconductor layer on the light emitting element side and the electrode on the submount side are in direct contact and short-circuited, which greatly affects the reliability of the product.

As described above, when a composite device is formed together with the light emitting device using the submount, the bulk can be reduced by the amount of wire bonding, but the mounting stability of the light emitting device on the submount is not sufficient. It is easy to cause the deterioration of the property.

An object of the present invention is to provide a semiconductor light emitting device which can be stably mounted on a submount without tilting a light emitting element and can maintain good light emission luminance and high reliability.

[0013]

According to the present invention, there is provided a semiconductor light emitting device comprising: a light emitting element having a compound semiconductor laminated on an insulating and light transmissive substrate; A submount for conducting and mounting the device in such a manner that the substrate faces the light emitting direction and the surface side of the compound semiconductor faces the mounting surface side, and the total number of the p electrode and the n electrode of the light emitting device is at least three or more. And a polygonal base surrounded by a line segment connecting the p-electrode and the n-electrode.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 is a light emitting device in which a p-electrode and an n-electrode are respectively formed on a surface of a compound semiconductor laminated on an insulating and light-transmitting substrate, and the light-emitting device. A submount that conducts and mounts the substrate such that the substrate faces the light emitting direction and the surface side of the compound semiconductor faces the mounting surface side, and the total number of the p electrode and the n electrode of the light emitting element is at least three or more, A semiconductor light-emitting device capable of forming a polygonal base surrounded by a line segment connecting these p-electrodes and n-electrodes. Since the light-emitting elements are mounted on three or more support points on the submount, the mounting is stable. This has the effect of improving the bonding property and improving the bonding strength by mounting the light emitting element so as to have a base having a shape of a triangle or more.

According to a second aspect of the present invention, in the submount, an electrode pattern for conducting the p-electrode and the n-electrode of the light emitting element with a positive polarity or a reverse polarity is formed on the surface, and at least three of the light emitting elements are formed. 2. The arrangement according to claim 1, wherein a relationship is provided between the arrangement pattern of the p-electrodes and the n-electrodes and the electrode pattern of the sub-mount to give a degree of freedom in a mounting position of the light-emitting element with respect to the sub-mount. This is a semiconductor light emitting device, and has an effect that when a light emitting element is mounted on a submount, assembly can be performed even when a mounting position of the light emitting element is slightly shifted from a set position.

According to a third aspect of the present invention, the p-electrode and the n-electrode of the light-emitting element and the electrode pattern of the submount are formed by bump electrodes formed on either the light-emitting element side or the submount side. 3. The semiconductor light emitting device according to claim 2, wherein the semiconductor light emitting device is connected in a conductive manner, and when the bump electrodes are joined by a load of ultrasonic vibration, the bump electrodes can be mounted almost uniformly and without a bias load. Has an action.

FIG. 1 is a schematic plan view of a semiconductor light emitting device according to an embodiment of the present invention, FIG. 2 is a bottom view of a light emitting element, and FIG.
(A) and (b) of FIG.
It is a longitudinal cross-sectional view by the arrow B.

In FIGS. 1 to 4, the semiconductor light emitting device comprises:
Light-emitting element 1 emitting blue light using GaN-based compound semiconductor
And a submount 2 for mounting and supporting the same.

As described in the conventional example, the light emitting element 1
Substrate 1 using light-transmissive and insulating sapphire
a and n-type layers 1b and G of GaN grown on the surface thereof
It is a laminate with the aN p-type layer 1c and has a substantially square planar shape. Then, in FIG. 2, the p-type layer 1c is partially removed by etching to expose the n-type layer 1b at the upper and lower corners on the left side.
A first n-electrode 3a and a second n-electrode 3b are respectively formed on the surface of the mold layer 1b. Further, a p-electrode 4 is provided on the surface of the p-type layer 1c substantially at the center on the right side. The first and second n-electrodes 3a and 3b and the p-electrode 4 are formed, for example, using Au as a material by a metal vapor deposition method.

The submount 2 has a base material 2a made of a metal such as iron or copper and an insulating film 2b laminated on the surface thereof, and further has an electrode pattern formed on the surface of the insulating film 2b. . The submount 2 has a rectangular planar shape, and the size of the long side is about 1.5 to 1.8 times the length of one side of the light emitting element 1 and the short side is the light emitting element 1
A little longer than. The electrode pattern on the surface of the insulating film 2b is formed by laminating a metal film layer of Al or the like on the surface of the insulating film 2b and etching the U-shaped electrode. And an electrode 6.

As shown in FIG. 1, the p-side electrode 5 is formed in a range extending linearly from the center of the right side of the submount 2 to the left, and a bonding pad 5a for wire bonding is laminated on the upper surface at the right end. are doing. The n-side electrode 6 extends around the p-side electrode 5 and occupies a substantially U-shaped region. A bonding pad 6a for wire bonding is formed at the right end of the upper half region.

In the manufacture of a semiconductor light emitting device composed of a composite of the light emitting element 1 and the submount 2, the light emitting element 1 is formed by forming a thin film layer of a GaN compound semiconductor on a sapphire-based wafer as in the prior art. After forming the substrate 1a and the n-type and p-type layers 1b and 1c, the first and second n-electrodes 3a and 3b and the p-electrode 4 are formed by a metal deposition method.
Then, after bump electrodes 7a, 7b, 7c are formed on each of these electrodes 3a, 3b, 4 by plating or stud bumps, the wafer is diced into chips to form a single light emitting element 1 shown in the figure. obtain. On the other hand, the submount 2 prepares a sheet material in which an insulating film 2b is formed on the surface of a base material 2a, and after laminating a metal film, etches the p-side and n-side electrodes 5, 6 to form a sheet. Form.

With respect to a single chip of the light emitting element 1 and a sheet material serving as a submount material in which p-side and n-side electrodes 5 and 6 are formed on the surface, the sheet material is mounted on a mounting table, and the light emitting element 1 is mounted. It is mounted according to the patterns of the p-side and n-side electrodes 5 and 6 of the sheet material. In this mounting process, as is clear from FIG. 1, the first and second n-electrodes 3a,
3b is on the n-side electrode 6 of the sheet material, and
Positioning is performed so as to correspond to each of the side electrodes 5. At this time, ultrasonic vibration is applied so that the bump electrodes 7a, 7b, 7c of the respective electrodes 3a, 3b, 4 of the light emitting element 1 are joined, and the p-side and n-side electrodes 5 of the sheet material side are applied. ,
Weld to 6. Then, by dicing the sheet material, a semiconductor light emitting device using a composite of the light emitting element 1 and the submount 2 shown in FIGS. 1 and 3 can be obtained.

Note that, before mounting the submount 2 on the sheet material, instead of dicing the light emitting element 1 into a single chip, the light emitting element 1 is diced into a pattern shape including a plurality of light emitting elements 1 and mounted on the sheet material. After that, a similar semiconductor light emitting device can be obtained by dicing the sheet material so that the light emitting elements 1 are included one by one.

After the manufactured semiconductor light emitting device is mounted on a lead frame or a printed wiring board (both not shown), as shown in FIGS. 1 and 3, the p-side and n-side of the submount 2 are mounted. Bonding pads 5 for electrodes 5 and 6
The wires 8a and 8b are bonded to the wires a and 6a, respectively, so that the wires 8a and 8b are electrically connected to a circuit on a lead frame or a printed wiring board.

In the above configuration, the light-emitting element 1 has the first
It is mounted on the submount 2 side by three electrodes of the second n-electrodes 3a and 3b and the p-electrode 4, and is held by three-point support. These electrodes 3a, 3b, 4 are formed at positions near the outer edge of the light emitting element 1 as shown in FIG. 2, and the electrodes 3a, 3b, 4 and the bump electrodes 7a, 7b, 7c are formed.
The size of the base formed by the triangle formed by the light-emitting element 1 occupies approximately half of the entire light-emitting element 1. Therefore, the light emitting element 1 is stably fixed on the submount 2, and mounting without inclination of the posture becomes possible. Further, as compared with the conventional connection using two electrodes, the bonding strength is increased by the three-point support, so that a stable support structure is maintained and the reliability of the product is greatly improved.

As is apparent from FIG. 1, both the p-side electrode 5 and the n-side electrode 6 of the submount 2
Even if the electrode 4 and the first and second n-electrodes 3a, 3b are displaced in the left-right direction, the conductive mounting is possible. That is, in the state of FIG. 1, the first and second n-electrodes 3a and 3b are located at the left end of the n-side electrode 6, but if the mounting position of the light emitting element 1 with respect to the submount 2 is shifted to the right, The bump electrodes 7a, 7b of these first and second n-electrodes 3a, 3b are n
It remains on the side electrode 6. Since the p-side electrode 5 of the bump electrode 7c of the p-side electrode 4 extends rightward, the conductive mounting on the p-side electrode 5 is similarly maintained. Therefore, in FIG. 1, for example, if the mounting position of the light emitting element 1 on the submount 2 is set at the center position in the left-right direction, even if the light emitting element 1 is displaced to the left or right during mounting, the conduction is maintained. A good implementation is possible. For this reason, in FIG. 1, the positioning accuracy of the mounting of the light emitting element 1 only needs to be strictly controlled in the vertical direction, the control for the mounting handling is simplified, and the reliability of the product is improved.

FIG. 4 is a schematic diagram showing another example of the pattern of the electrodes provided on the light emitting element 1 and the submount 2, and shows the shape of the bottom surface of the light emitting element 1 including the electrodes provided on the submount 2.

FIG. 4A shows that the light emitting element 1 has a third bottom surface in addition to the first and second n-electrodes 3a and 3b shown in the previous example.
The n-electrode 3c and the fourth n-electrode 3d are provided at corners, and the p-electrode 4 is arranged at the center. That is,
The first and third n-electrodes 3a and 3c are located in the upper half region of the n-side electrode 6 of the submount 2 in FIG.
The electrodes 3b and 3d correspond to the lower half region, and the p-electrode 4 is included in the p-side electrode 5 of the submount 2. In this example, since the number of electrodes is five, the mounting stability of the light emitting element 1 on the submount 2 is further improved, and the degree of freedom in positioning the mounting of the light emitting element 1 on the submount 2 as in the previous example. Can also have.

FIG. 4B does not include the fourth n-electrode 3d in the example of FIG. 4A and supports two points on the right end of the light emitting element 1, so that the p-electrode 4 is the same as the example of FIG. It is an arrangement. In this example, the light-emitting element 1 is supported by four electrodes, and the number of support points is smaller by one than in the case of FIG. 3A, but the first and second n-electrodes 3a and 3b, the third n-electrode 3c, and the p-electrode Since the base of the trapezoid formed by 4 can be widened, stable mounting on the submount 2 is also possible.

FIG. 4C shows the first and second n-electrodes 3a, 3a.
b is the same as the pattern shown in FIGS.
The p-electrode 4 is formed on the entire surface of the p-type layer 1c except for the etching surface. In this example, the first and second n-electrodes 3a, 3b
3, the bump electrodes 7a and 7b are formed and joined to the n-side electrode 6 on the submount 2 side.
Is a whole surface electrode, it is preferable to form a bump electrode (not shown) on the p-side electrode 5 on the submount 2 side. When the light emitting element 1 is mounted on the submount 2, the area of the p-electrode 4 is wide, so that the degree of freedom in joining the bump electrode of the p-side electrode 5 of the submount 2 is increased, and the handling of mounting is further simplified. Become.

[0032]

According to the present invention, the light emitting element has three or more electrodes, and these electrodes have a base having an area ratio of, for example, half or more of the light emitting element, so that The product can be mounted stably, and when the light emitting element is mounted on the submount, there is no inclination of the light emitting element or short circuit between electrodes, and a product having high emission luminance and high reliability can be obtained. Also, by setting the electrode of the light emitting element and the electrode pattern on the submount side to have a degree of freedom of the mounting position of the light emitting element, the handling of mounting the light emitting element on the submount is facilitated, and the manufacturing yield is increased. Also improve.

[Brief description of the drawings]

FIG. 1 is a plan view of a semiconductor light emitting device according to an embodiment of the present invention.

FIG. 2 is a bottom view of a light emitting element of the semiconductor light emitting device of FIG. 1;

3A and 3B are diagrams showing a conduction structure between a light emitting element and a submount of the semiconductor light emitting device of FIG. 1, wherein FIG.
FIG. 1B is a longitudinal sectional view taken along line BB of FIG. 1.

FIG. 4 is a schematic view showing an example of an arrangement pattern of a p-electrode and an n-electrode provided on the bottom surface of a light-emitting element.

[Explanation of symbols]

 Reference Signs List 1 light emitting element 1a substrate 1b n-type layer 1c p-type layer 2 submount 2a base material 2b insulating film 3a first n-electrode 3b second n-electrode 3c third n-electrode 3d fourth n-electrode 4 p-electrode 5 p-side electrode 5a bonding pad 6n Side electrode 6a Bonding pad 7a, 7b, 7c Bump electrode 8a, 8b Wire

Claims (3)

[Claims] 1. A light-emitting element in which a p-electrode and an n-electrode are respectively formed on a surface of a compound semiconductor laminated on an insulative and light-transmitting substrate; A submount for conducting and mounting the compound semiconductor such that the surface side of the compound semiconductor faces the mounting surface side, wherein the total number of the p-electrode and the n-electrode of the light-emitting element is at least three or more, and a line segment connecting the p-electrode and the n-electrode is provided. Semiconductor light emitting device capable of forming a polygonal base surrounded by 2. The light emitting device according to claim 1, wherein the submount is a light emitting element.
Forming an electrode pattern on the surface for conducting the electrode and the n-electrode with a positive polarity or a reverse polarity;
2. The arrangement that gives a degree of freedom to a mounting position of the light emitting element with respect to the submount, between an arrangement pattern of at least one p electrode and n electrode and the electrode pattern of the submount. 3. Semiconductor light emitting device. 3. The p-electrode and the n-electrode of the light-emitting element and the electrode pattern of the submount are electrically connected by a bump electrode formed on one of the light-emitting element side and the submount side. 3. The semiconductor light emitting device according to 2.