JPH08330633A - Light-emitting semiconductor device - Google Patents

Abstract

PURPOSE: To obtain a light-emitting semiconductor device which eliminates high costs and a drop in productivity when a semiconductor light-emitting element is mounted on a circuit board and which can eliminate an irregularity in the contact resistance of the light-emitting semiconductor element with the circuit board. CONSTITUTION: In a light-emitting semiconductor device, an island-shaped semiconductor layer composed of at least two semiconductor layers which contain different impurities is formed on a semiconductor substrate, and a light-emitting semiconductor element 1 in which one pair of electrodes have been formed on the island-shaped semiconductor layer is mounted on a circuit board 2 to be mounted. The electrodes are formed on the same side as the island-shaped semiconductor layer on the semiconductor substrate, metal bumps 10 are installed so as to protrude on the electrodes 6, 7, flexible anisotropic conductive films 3 are interposed between the electrodes and the board 2 to be mounted, the semiconductor light-emitting element is mounted on the board to be mounted, and a light-transmitting resin 14 is interposed between the island-shaped semiconductor layer and the board to be mounted.

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 provided with an LED array used as a light source for exposing a photosensitive drum for a page printer, and more particularly to a semiconductor light emitting element on an adhered circuit board via an anisotropic conductive film. The present invention relates to a semiconductor light emitting device in which the semiconductor light emitting element and the adherend circuit board are connected together with a translucent resin interposed therebetween.

[0002]

2. Description of the Related Art As a semiconductor light emitting device, as shown in FIG. 5, a light emitting element 102 composed of a plurality of semiconductor layers is formed on one main surface 101a of a semiconductor substrate 101, and on this light emitting element 102. The individual electrodes 103 are formed on the semiconductor substrate 101 from the semiconductor substrate 101 to the semiconductor substrate 101.
The one in which the common electrode 104 is formed on the other main surface 101b of 01 is conventionally known. This semiconductor light emitting device 10
5 is mounted on the adhered circuit board on which the drive circuit is formed, as shown in FIG. 6, the common electrode 104 of the semiconductor light emitting element 105 is connected via the conductive paste 107 to the common wiring on the adhered circuit board 106. The light emitting element 10 is connected to 108.
The individual electrodes 103 provided for every two are connected to the individual wirings 110 on the adhered circuit board 106 by the bonding wires 109 one by one.

Although a large number of light emitting elements 102 are provided in a row, 111 in FIG. 6 is a large number of light emitting elements 10.
2 is a driving IC that selectively emits light.

However, like the above semiconductor light emitting device,
When the individual electrodes 103 are connected to the wirings 110 on the adhered circuit board 106 one by one, the light emitting element 102 is 30 at most.
There is a problem in that it can only handle densities of about 0 to 400 dpi. That is, when the density is higher than that, the individual electrode 103 of the light emitting element 102 and the individual wiring 110 of the adhered circuit board 106 cannot be connected by the bonding wire 109.

When the individual electrodes 103 of the light emitting elements 102 and the individual wirings 110 of the adhered circuit board 106 are individually connected by the bonding wires 109, if the light emitting elements 102 have a high density, the productivity is lowered and the wires are There is a problem that the workability of bonding is complicated and the cost is high.

Therefore, as shown in FIG. 7, each light emitting element 1
No. 02 individual electrode 103 and common electrode 104 ′ are provided on one main surface 101 a of the semiconductor substrate 101.
3 and the common electrode 104 ′ to form gold bumps 112, respectively, to form the semiconductor light emitting element 105, and the semiconductor light emitting element 105 is phenol-bonded to the common wiring 108 and the individual wiring 110 of the adhered circuit board 106 by the micro bump bonding method. It has been proposed to press and connect with the contraction force of the resin 113 or the like.

However, in this conventional semiconductor light emitting device, the height of the gold bump 112 is required to be 15 to 20 μm, and the gold bump 112 is bonded to the common wiring 108 and the individual wiring 110 on the adhered circuit board 106. Without
Since they are brought into contact with each other to be connected, the connection state varies depending on the height of the gold bump 112, the connection becomes unstable and the contact resistance varies, and the light emitting characteristics of the light emitting element 102 become uneven. There is a problem that it takes a long time to form the gold bump 112.

[0008]

SUMMARY OF THE INVENTION The semiconductor light emitting device according to the present invention has been invented in view of the above problems of the conventional device.
It is possible to provide a semiconductor light emitting device that eliminates the reduction in productivity and the cost increase when mounting a semiconductor light emitting element on an adhered circuit board, and eliminates the variation in the contact resistance between the semiconductor light emitting element and the adhered circuit board. To aim.

[0009]

In order to achieve the above object, in a semiconductor light emitting device according to the present invention, an island-shaped semiconductor layer composed of at least two semiconductor layers containing different semiconductor impurities is provided on a semiconductor substrate. In a semiconductor light emitting device provided with a semiconductor light emitting element having a pair of electrodes for flowing a current through the island-shaped semiconductor layer, the semiconductor light emitting element is mounted on a target circuit board,
The electrode is provided on the same side of the semiconductor substrate as the semiconductor layer, and gold bumps are provided so as to project on the electrode, and an anisotropic conductive film is interposed between the electrode and the adherend substrate to form the semiconductor. A light emitting element was mounted on the adherend substrate, and a translucent resin was interposed between the island-shaped semiconductor layer and the adherend substrate.

[0010]

With the above structure, when the semiconductor light emitting element is mounted on the adhered circuit board, a large number of electrodes on the light emitting element side and a large number of electrodes on the adhered circuit board can be connected at one time, and the Even if the element has a high density, the productivity is not reduced.

Further, since the anisotropic conductive film has flexibility, the gold bumps can be formed low, and even if there is some variation in the height of the gold bumps, all the gold bumps can be used as the anisotropic conductive film. Connection can be made, and variation in contact resistance between the semiconductor light emitting element and the adhered circuit board can be eliminated.

[0012]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. FIG. 1 is a diagram showing an embodiment of a semiconductor light emitting device according to the present invention, in which 1 is a semiconductor light emitting element, 2 is a circuit board to be adhered, and 3 is for connecting the semiconductor light emitting element 1 and the circuit board 2 to be adhered. Is an anisotropic conductive film.

As shown in FIG. 2, the semiconductor light emitting device 1 shown in FIG. 1 is mainly composed of a plurality of light emitting devices (LEDs) 5 arranged in a line on one main surface 4a of a semiconductor substrate 4 made of, for example, silicon. The individual electrode (anode electrode) 6 formed for each light emitting element 5 on the one main surface 4a of the semiconductor substrate 4 and both sides of each light emitting element 5 on the one main surface 4a of the substrate 4. And a common electrode (cathode electrode) 7.

In the light emitting device 5, a semiconductor crystal film is formed on one main surface 4a of the semiconductor substrate 4 by metalorganic vapor phase epitaxy (MO).
CVD) or molecular beam epitaxy (MBE) and the like, and the growth layer can be formed by etching while leaving a portion to be the light emitting element 5, for example, as shown in FIG.
Gallium arsenide (GaAs), gallium arsenide phosphide (GaA)
buffer layer 5a, which is a growth layer of sP), gallium phosphide (GaP), or the like, and aluminum gallium arsenide (Al _x Ga).
_1-x As) growth layer, which is an n-type semiconductor layer 5b, a p-type semiconductor layer 5c, and ap ^{+ -type} semiconductor layer 5d, and is further protected by silicon nitride (SiN _x ) or silicon oxide (SiO ₂ ). It can be formed by forming the film 8 by plasma CVD or the like.

Each individual electrode 9 is exposed by removing a part of the protective film 8 covering each light emitting element 5 by etching p ^+.
2 is connected to the semiconductor layer 5d, and as shown in FIG. 2, the light-emitting elements 5 are drawn out in a direction (vertical direction in FIG. 2) perpendicular to the parallel direction (horizontal direction in FIG. 2) and to one side side. The drawn-out pieces and the drawn-out pieces on the other side are alternately arranged in parallel, and gold bumps (conductive members) 10 are formed on the drawn-out ends.

Each common electrode 7 is connected to one main surface 4a of the semiconductor substrate 4 which is exposed by removing a part of the protective film 8 by etching, and is formed into a strip shape along the arrangement of the light emitting elements 5, and above it. A plurality of gold bumps (conductive members) 10 are formed at intervals.

Each gold bump 10 is covered with a resist except for bump forming portions having a diameter of several tens of μm on the electrodes 6 and 7, and then gold is deposited by electroplating to a thickness of about 3 to 4 μm. Can be formed. As the composition of the plating solution, for example, potassium gold cyanide of 4 to 8 is used.
% By weight, 30-40% by weight potassium citrate, 30-40% by weight potassium monophosphate, 20-3% citric acid.
It is possible to use a liquid in which 0% by weight and nickel diamine diacetate of 2 to 3% by weight are mixed. In the electroplating, short-circuit wirings that connect all the electrodes 6 and 7 to each other are provided in a state where a plurality of light-emitting elements 5 are formed on a silicon wafer, and the electrodes 6 and 7 are used as plating electrodes through the short-circuit wirings. When the light emitting elements 5 are separated from each other by dividing the wafer by connecting the short-circuit wiring to each electrode 6,
You may make it cut | disconnect between 7 mutual.

Further, as shown in FIG. 4, the electrode 7 is formed of an aluminum thin film, and chromium (Cr) 11a and nickel (Ni) 11 are provided between the electrode 7 and the gold bump 10.
It is also possible to interpose a three-layer metal film 11 in which b and gold (Au) 11c are sequentially grown by vapor deposition or sputtering.

In the semiconductor light emitting device 1, as shown in FIG. 1, the anisotropic conductive film 3 is interposed between the gold bump 10 and the wiring of the adhered circuit board 2 to form the semiconductor light emitting element 1 and the adhered circuit. The board 2 is connected.

The anisotropic conductive film 3 is formed of a resin film,
Fine particles coated with metal such as nickel or carbon are dispersed, and a tape is attached to one side of the film. The tape is peeled off, and the electrodes 6 and 7 of the semiconductor light emitting device 1 on which the gold bumps 10 are formed and the wirings 12 and 13 of the adhered circuit board 2 are aligned so that they are just connected, and the wirings 6 and 7 of the adhered circuit board 2 are aligned. Anisotropic conductive film 3 is placed on top and pressure-bonded.

The pressure bonding is a two-stage system in which heat of about 60 ° C. to 70 ° C. is first applied for temporary pressure bonding, and then heat of 170 ° C. is applied for main pressure bonding. At this time, the metal-coated plastic balls at the positions where the gold bumps 10 of the semiconductor light emitting element 1 and the wirings 12 and 13 of the adhered circuit board 2 are just connected are crushed, and the anisotropic conductive film 3 acts as an adhesive. At the same time, the gold bumps 10 of the semiconductor light emitting device 1 and the adhered circuit board 2
It also has a role of conducting electricity between the wirings 12 and 13.

In the region other than the region where the gold bump 10 is provided, the metal ball coated with the metal in the anisotropic conductive film 3 is not crushed and the insulating property is maintained.

In the micro bump bonding method, the gold layer must have a thickness of about 15 to 20 μm.
The method using the anisotropic conductive film 3 requires about 3 to 4 μm.

Although a gap is formed between the light emitting element 1 and the adhered circuit board 2, in order to guide the light of the light emitting element 1 to the adhered circuit board 2 and efficiently radiate it from the back side of the adhered circuit board 2. It is preferable that the transparent resin 14 such as silicon resin is filled in the gap. By thus filling the gap between the light emitting element 1 and the adhered circuit board 2 with the silicone resin 14, irregular reflection of light in the air layer, which would occur when the silicone resin 14 is not present, can be prevented, and the light of the light emitting element 1 can be efficiently emitted. It can be well radiated to the adhered circuit board 2.

In this case, in order to protect the semiconductor light emitting element 1 as well as the gap between the light emitting element 5 and the adhered circuit board 5, the entire peripheral portion of the semiconductor light emitting element 1 is covered with a transparent resin. May be.

[0026]

As described above, according to the semiconductor light emitting device of the present invention, since the semiconductor light emitting element and the adhered circuit board are connected through the anisotropic conductive film, the light emitting element has a high density. However, the electrodes of a large number of light emitting elements and the wirings of the adhered circuit board can be connected at one time, the productivity can be remarkably improved, and the connection reliability is improved.

Further, since the transparent resin is filled in the gap between the light emitting element and the adhered circuit board, the light of the light emitting element can be efficiently radiated from the rear surface side of the adhered circuit board.

[Brief description of drawings]

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

FIG. 2 is a plan view of a semiconductor light emitting element used in the semiconductor light emitting device according to the present invention.

FIG. 3 is a cross-sectional view of a semiconductor light emitting element used in a semiconductor light emitting device according to the present invention.

FIG. 4 is an enlarged view showing a connection portion between a semiconductor light emitting element and an adhered circuit board in a semiconductor light emitting device according to the present invention.

FIG. 5 is a cross-sectional view showing a conventional semiconductor light emitting device.

FIG. 6 is a cross-sectional view showing a conventional semiconductor light emitting device.

FIG. 7 is a cross-sectional view showing another conventional semiconductor light emitting device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Semiconductor light emitting element, 2 ... Adhered circuit board, 3 ...
..Anisotropic conductive film

Claims (1)

[Claims] 1. A semiconductor light-emitting device comprising a semiconductor substrate, an island-shaped semiconductor layer including at least two semiconductor layers containing different semiconductor impurities, and a pair of electrodes for passing a current through the island-shaped semiconductor layer. In a semiconductor light emitting device in which an element is mounted on an adhered circuit board, the electrode is provided on the same side of the semiconductor substrate as the semiconductor layer, and a gold bump is provided on the electrode so as to project therefrom. The semiconductor light emitting element is mounted on the adherend substrate with an anisotropic conductive film interposed therebetween, and a translucent resin is interposed between the island-shaped semiconductor layer and the adherend substrate. And a semiconductor light emitting device.