JPH11135835A - Light emitting device and method of manufacturing the same - Google Patents

Abstract

(57) Abstract: A light-emitting element mounted such that a PN junction surface is substantially perpendicular to a substrate has a short distance between the PN junction surface and an end of an electrode. There was a risk of short-circuiting due to contact with the pattern and causing a leak. SOLUTION: In a light emitting element having electrodes at both ends, which has a PN junction surface and is mounted so that the PN junction surface is substantially perpendicular to a substrate, a metal in which at least one of the electrodes is thickened by plating. By being formed by,
The distance between the PN junction surface and the pattern on the substrate can be increased, and the reliability can be improved.

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 such as a light emitting diode (LED) and a method for manufacturing the same, and more particularly, to a light emitting device having a PN junction surface substantially perpendicular to a substrate and a method for manufacturing the same. About.

[0002]

2. Description of the Related Art A dot matrix LED display device has been commercialized as a unit having a plurality of light emitting diodes, and an LED chip is generally die-bonded such that a PN junction surface is horizontal to a unit substrate. Furthermore, it is mounted by wire bonding to the LED chip, but recently, in order to increase the packaging density, the LED in which the PN junction surface of the light emitting diode is formed to be perpendicular to the substrate
Display devices have been developed.

FIG. 4 is a side view showing a state in which a conventional light emitting element is mounted on a substrate. The LED chip 50 has a PN junction surface 53, and thick film electrodes 54 and 55 of about 50 μm formed of Ag paste or the like are formed on both ends thereof. This LED chip 50 is formed by a pattern 5 on a substrate 56.
7 and 58 are provided by a conductive adhesive or an anisotropic conductive adhesive.

Normally, the thickness of the P-type semiconductor layer and the thickness of the N-type semiconductor layer of the LED chip are different, and the PN junction plane is shifted not to the center of the crystal but to either the P-type semiconductor layer or the N-type semiconductor layer. ing. In this case, since the P-type semiconductor layer 52 is narrow, the mounting position of the LED chip 50 is shifted as shown in FIG. 4B, and the PN junction surface 53 is applied to the pattern 58, which may cause a leak.

FIG. 5 is a side view showing a state in which another conventional light emitting element is mounted on a substrate. The light emitting diode 61 is P
Electrodes 64 and 65 having an N-joint surface 63 and formed by depositing gold on both ends are formed. 65
Is an electrode formed on a P-type semiconductor, and 64 is an electrode formed on an N-type semiconductor. Each of the electrodes 64 and 65 has a thickness of 1 μm or less.

The light emitting diode 60 is placed horizontally so that the PN junction surface 63 is substantially perpendicular to the substrate 66. Patterns 67 and 68 formed by patterning a copper foil or the like are formed on the substrate 66. A spacer 69 formed of an insulating resin or the like is formed between the pattern 67 and the pattern 68. The light emitting diode 61 is temporarily fixed on the spacer 69 via an adhesive 70. By disposing the light emitting diode chip 60 on the spacer 69, it is possible to prevent the PN junction surface 63 from contacting the pattern 68 or the pattern 67 and short-circuiting the PN junction surface, thereby preventing leakage.

Next, the pattern 67 and the electrode 64 are soldered 71
Connect through. Further, the pattern 68 and the electrode 65 are connected by the solder 72, and the light emitting diode 60 is connected to the substrate 6.
6 electrically.

The electrodes 64 and 65 are very thin because they are formed by evaporation, and the P-type semiconductor layer 62 is also very thin because it is formed by epitaxial growth.
And the P-type semiconductor layer together is about several μm to several tens μm. Therefore, in order to mount a chip on the substrate 66 so that the P-type semiconductor layer and the N-type semiconductor layer are not short-circuited, the electrode 6
The large solders 71, 72 must be interposed between the patterns 4, 65 at a sufficient distance from the patterns 67, 68. For this reason, the solders 71, 72 are precisely arranged so that the solders 71, 72 do not go around the side surfaces of the chip. There must be.

Further, when the mounting position of the light emitting diode 51 is shifted due to defective solder installation or the like as shown in FIG. 5B, the PN junction surface 51c may come into contact with the pattern and cause a short circuit. . Further, since it is necessary to temporarily fix to the substrate, the number of steps is increased and the cost is increased.

[0010]

In a light emitting device mounted so that the PN junction surface is substantially perpendicular to the substrate of the conventional example, the distance between the PN junction surface and the end of the electrode is short. There was a risk that the surface would contact the pattern on the substrate and short-circuit, causing a leak.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a highly reliable semiconductor device and a method for manufacturing the same, which reliably prevent a short circuit at the time of mounting a light emitting device such as an LED chip. With the goal.

[0012]

According to a first aspect of the present invention, there is provided a light emitting device having a PN junction surface, and light emitting elements having electrodes at both ends mounted so that the PN junction surface is substantially perpendicular to the substrate. In the device, at least one of the electrodes is formed of a metal whose thickness is increased by plating.

Further, the light emitting device according to the second aspect of the present invention is characterized in that the electrode closer to the PN junction surface is formed thicker than the other electrode.

According to a third aspect of the present invention, at least one of the electrodes of the light emitting element is formed by solder plating.

The light emitting device according to claim 4 of the present invention is the light emitting device according to claim 2, wherein
The bonding surface is located substantially at the center of the light emitting element.

According to a fifth aspect of the present invention, there is provided a method for manufacturing a light emitting device, comprising the steps of providing thin film electrodes on both surfaces of a semiconductor substrate having a PN junction surface, and plating at least one of the thin film electrodes with a thick metal by plating. Forming an electrode by forming
Dividing the semiconductor substrate in the thickness direction to form a plurality of light-emitting elements.

[0017]

FIG. 1 is a partially enlarged view showing a method for manufacturing a light emitting device according to an embodiment of the present invention. Also,
FIG. 2 is a perspective view showing a light emitting device according to one embodiment of the present invention. In FIG. 1A, a semiconductor substrate LE
The D wafer 18 has a P-type semiconductor layer 12 of about 50 μm formed on an N-type semiconductor layer 11 of about 200 μm, and has a PN junction surface 13. Au is applied on both sides of this semiconductor wafer.
The electrodes 14 and 15 are formed by a sputtering method or the like. The thickness of the Au electrode, which is a thin film electrode, is 1 μm or less.

Next, as shown in FIG.
Metal electrodes are laminated by solder plating on the Au electrodes 14 and 15 on the D wafer 18 to form terminal electrodes 16 and 17 having a large thickness. The solder used is 9-1 solder (Sn: Pb = 9:
1) is used. At this time, the side near the PN junction surface 13 of the LED wafer is formed thick. The thickness of the terminal electrode 17 is 2
The thickness of the terminal electrode 16 is about 50 μm.

Since the Ag paste has a large shrinkage at the time of curing, when a thick-film terminal electrode is formed with the Ag paste, L
Stress is applied to the ED wafer. In particular, if the terminal electrodes on both sides of the chip have different thicknesses, the chip is warped such that the side of the thickly formed terminal electrode is on the inside. For this reason, it becomes difficult to process the LED wafer, stress is applied to the LED wafer, and cracks occur. On the other hand, the terminal electrodes 17 and 18 formed of the solder paste do not have the curing shrinkage unlike the Ag paste, and since the solder paste is soft, the formed wafer does not warp.

Next, as shown in FIG. 1 (c), a semiconductor wafer is attached to an adhesive sheet 30.
The wafer 18 is subjected to full dicing (L
The EDLED wafer 18 and the terminal electrodes 16 and 17 are cut together. ) To divide the LED wafer 18 into a plurality of LED chips 10. The dicing pitch is about 0.3 mm, and the thickness of the dicing groove is about 60 μm.

Subsequently, an extensible adhesive sheet 31 is attached to the upper surface of the divided LED chips 10, the adhesive sheet 30 is peeled off, and the LED chips 10 are moved to the adhesive sheet 31. As shown in (2), the distance between the LED chips 10 is extended by stretching the adhesive sheet. Increasing the chip spacing facilitates chip testing and also facilitates etching in the next step.

Next, as shown in FIG.
After the chip 10 is further moved to the etching adhesive sheet 32, the chip 10 is immersed in the etching solution 19, and the LED chip 10
Is etched on the side surface of. As the etching solution 19, a solution containing phosphoric acid and hydrogen peroxide at a ratio of 3: 1 at 60 ° C. is used. By performing the etching, cracks generated on the side surfaces of the LED chip 10 by dicing are removed. At this time, the laminated terminal electrodes 16 and 17 are not etched.

The light emitting device shown in FIG. 2 is formed by the above steps. The semiconductor crystal portion of the LED chip 10 is:
A P-type semiconductor layer 12 is laminated on an N-type semiconductor layer 11 and has a PN junction surface 13. An Au electrode 14 is formed on the lower surface of the N-type semiconductor layer 11, and a terminal electrode 16 is formed by solder plating. On the other hand, an Au electrode 15 is formed on the upper surface of the P-type semiconductor layer, and a terminal electrode 17 is formed by solder plating.

The LED chip 10 has a width W of 3
The length L is about 200 to 300 μm. The thickness H is about 500 μm. The thickness of the N-side terminal electrode 16 is about 50 μm, the thickness of the N-type semiconductor layer 11 is about 200 μm, and the thickness of the P-type semiconductor layer 12 is about 50 μm. The thickness of the P-side terminal electrode 17 is about 200 μm. The PN junction surface 13 is 250 μm from the lower surface of the terminal electrode 16,
It is located approximately at the center of the D chip. The Au electrode 1
The thicknesses of 4 and 15 are 1 μm or less.

FIG. 3 is a side view showing a state where the light emitting device shown in FIG. 2 is set on a substrate. Patterns 21 and 22 are provided on the substrate 20. The distance D between the pattern 21 and the pattern 22 is about 160 μm. Anisotropic conductive paste 23 is formed on these patterns 21 and 22.
And 24 are applied respectively, and the LED chip 10 is set by a chip mounting device. Subsequently, by heating to about 150 ° C., the anisotropic conductive paste is cured, and the LED chip 10 is fixed to the substrate 20. The terminal electrode 16 and the pattern 21 are electrically connected, and the terminal electrode 17 and the pattern 22 are electrically connected.

Since no connection is made by soldering or the like, thermal stress applied to the chip can be reduced. Since the PN junction surface 13 is located at the center of the chip, if the mounting accuracy of the chip mounting device is less than ± 80 μm, there will be no leakage after mounting, but the accuracy of recent chip mounting devices is about ± 30 μm, which is sufficient. Since the PN junction surface 13 is located substantially at the center, the interval between the pattern 21 and the pattern 22 can be set substantially at the allowable limit of the mounting accuracy, and the reliability of LED chip mounting can be increased.

In the present invention, the terminal electrodes which are thickened by plating are formed on both sides of the semiconductor wafer, but may be formed on only one side. That is, by forming a terminal electrode whose thickness is increased by plating near the PN junction surface,
The N junction surface can be located at a position near the center of the LED chip.

Although the present invention has been described with reference to an LED as a light emitting device having a PN junction surface, the present invention can be applied to other light emitting devices having a PN junction surface, for example, a semiconductor laser.

[0029]

According to the light emitting device of the first aspect of the present invention, the light emitting device has a PN junction surface, and has electrodes at both ends mounted so that the PN junction surface is substantially perpendicular to the substrate. Wherein at least one of the electrodes is formed of a metal whose thickness has been increased by plating,
The distance between the bonding surface and the pattern on the substrate can be increased, and the reliability can be improved.

According to the second aspect of the present invention, the electrode closer to the PN junction is formed thicker than the other electrode, so that the PN junction is closer to the center of the light emitting element. Therefore, the PN junction surface does not contact the pattern on the substrate, and the reliability can be improved.

According to the third aspect of the present invention, since at least one of the electrodes of the light emitting element is formed by solder plating, a highly reliable light emitting element resistant to thermal stress can be obtained. Can be.

The light emitting device according to a fourth aspect of the present invention is the light emitting device according to the second aspect, wherein
The bonding surface is substantially at the center of the light emitting element, and the PN bonding surface does not contact the pattern of the substrate, so that the reliability can be improved.

According to a fifth aspect of the present invention, there is provided a method of manufacturing a light emitting device, comprising the steps of: providing thin film electrodes on both surfaces of a semiconductor substrate having a PN junction surface; and plating at least one of the thin film electrodes with a thick metal by plating. Forming an electrode by forming
Forming a plurality of light emitting elements by dividing the semiconductor substrate in the thickness direction,
When mounted on a substrate such that the PN junction surface is vertical, a highly reliable light emitting element can be manufactured.

[Brief description of the drawings]

FIG. 1 is a partially enlarged view showing a method for manufacturing a light emitting device according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a light emitting device according to one embodiment of the present invention.

FIG. 3 is a side view showing a state where the light emitting device shown in FIG. 2 is installed on a substrate.

FIG. 4 is a side view showing a state where a light emitting element of a conventional example is mounted on a substrate.

FIG. 5 is a side view showing a state in which another conventional light emitting element is mounted on a substrate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 LED chip 11 N-type semiconductor layer 12 P-type semiconductor layer 13 PN junction surface 14, 15 Au electrode 16, 17 Terminal electrode 18 LED wafer 20 Substrate

Claims (5)

[Claims] 1. A light emitting device having a PN junction surface and electrodes at both ends mounted so that the PN junction surface is substantially perpendicular to the substrate, wherein at least one of the electrodes is made thicker by plating. A light-emitting element formed of a metal. 2. The light emitting device according to claim 1, wherein an electrode closer to the PN junction surface is formed thicker than the other electrode. 3. The light emitting device according to claim 1, wherein at least one of the electrodes of the light emitting device is formed by solder plating. 4. The light emitting device according to claim 2, wherein the PN junction surface of the light emitting device is substantially at the center of the light emitting device. 5. A step of providing thin-film electrodes on both surfaces of a semiconductor substrate having a PN junction surface, a step of forming an electrode by plating a metal on at least one of the thin-film electrodes, and forming the electrodes in a thickness direction. Forming a plurality of light-emitting elements by dividing into a plurality of light-emitting elements.