JPH09270528A - Light emitting diode element and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the quantity of light emission by forming steps on the side faces of a GaP light emitting diode element having an approximately parallel emitting junction to the surface or bottom face and forming natural fracture planes on the side faces as high as more than 2/3 of the height thereof. SOLUTION: Steps different in height are formed on adjacent side faces e.g. 13, 14 of a GaP light emitting diode element. The upper sides of such steps 18, 19 are cut to form fracture planes and natural fracture planes 28 are formed on the lower sides of them as high as more than 2/3 of the height thereof. Such steps 18, 19 are formed and natural fracture planes 28 are exposed to result in that the side face crystals of the element are deformed by the cutting to increase the light absorption due to the crystal damage, thus light emitting efficiency is more improved than that of an element having a perfect cleavage face or light emitting diode element having a cut fracture plane. Thus, the quantity of light emission is more than that of a light emitting diode element obtained by the dividing method such as dicing method or cleavage scribe.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a GaP light emitting diode device and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, in a light emitting diode element, as shown in JP-A-53-102685, a light emitting diode element having a wide light emitting junction, that is, a light emitting junction substantially parallel to a front surface or a bottom surface, is formed from a wafer. Almost dice-shaped light emitting diode elements are obtained by using a dicing method or the like, in which case a step is formed in the peripheral portion by mesa etching or the like. Such a step is a structure that is often used when it is desired to make the area of the light emitting junction larger than the surface area of the element, when the wafer is difficult to divide and is easily broken when the wafer is thin, and only when the divided portion is thinned and then divided. . It is well known from Japanese Patent Publication No. 51-23868 that surface roughening treatment may be performed in order to increase the light extraction amount of the light emitting diode.

[0003]

However, in the gallium phosphorous light emitting diode element, the element division is usually performed by the dicing method due to the degree of light absorption and the fragility of the crystal, and the light extraction of the light emitting diode in that case is performed. As a result of examining the amount, the light emitted from the side surface of the light emitting diode is
It has been found that the rough surface does not always improve, and especially when the crystal is transparent to the light emitted, the side close to the cleavage plane should be used.

[0004]

The present invention has been made on the basis of the results of such studies, and in a gallium phosphorous light emitting diode element having a light emitting junction substantially parallel to the surface or the bottom surface, a step is formed on the side surface thereof. Provided, the height of its side is 2
A natural fracture surface is provided at / 3 or more.

Further, according to the present invention, a shallow groove having a thickness of 1/3 or less of the thickness of a gallium phosphide wafer having a light emitting junction substantially parallel to the surface or the bottom surface is provided, and a scratch is provided on the surface or the bottom surface facing the shallow groove. The element is divided into individual elements at the scratched or grooved portion.

[0006]

FIG. 1 is a perspective view of a light emitting diode device according to an embodiment of the present invention, in which a crystal is transparent with respect to a light emission color, for example, a gallium phosphor yellow green light emitting diode device having an orange crystal (light emission wavelength). 565 nm) is taken as an example.
Unlike other crystals of gallium arsenide or gallium aluminum arsenide, gallium phosphide (or gallium phosphide: GaP) is the same light emitting diode because of the degree of light absorption and the fragility of the crystal.
Usually, element division is performed by a dicing method. This light emitting diode element has a substantially dice shape, one side is about 300 μm, and a surface and a bottom surface are substantially parallel to each other and each has an electrode 10. Then, on the front surface side, there is a light emitting junction 2 substantially parallel to the front surface or the bottom surface, which is, for example, approximately 30 to 50 from the front surface.
It is about 60,000 μm ² wide at a depth of μm.

The four side surfaces are provided with natural fracture surfaces 28 at 270 μm and 230 μm, which correspond to 2/3 or more of the height of the side surface from the bottom surface side. The side surfaces facing each other have the same shape, and adjacent side surfaces, for example, side surfaces 13 and 14 are provided with steps 18, 19 having different heights. The upper side of the steps 18, 19 forms a fracture surface by cutting, and the lower side of the step has a natural fracture surface. The step 18 has a step width of 1 to 50 at a position of 15 to 80 μm from the surface.
In μm, the shape may be stepwise or gentle. One step 19 is 20 to 90 μm from the surface
It is provided at m, and the step width and the cross-sectional shape do not change much. And more preferably, at least one of the side surfaces is aligned with a surface close to the cleavage surface, and in that case, the substrate side (bottom surface side) of one step is substantially a plurality of cleavage surfaces.

Such a light emitting diode device is obtained as follows. Referring to FIG. 2, first, a gallium phosphide wafer 1 having a light emitting junction 20 substantially parallel to the surface or the bottom surface.
A groove 4 deeper than the light emitting junction 20 but sufficiently shallower than ⅓ of the thickness is provided so as to be substantially orthogonal to the cleavage direction A. Next, the shallow groove 3 is provided substantially along the cleavage direction A. As a result, the shallow groove 3 and the deep groove 4 are substantially orthogonal to each other, and the light emitting junction 20 is divided into square shapes. Then, a scribing line 5 is inserted at the diamond point on the bottom surface facing the grooves 3 and 4, and scribing is performed.
Then, the element provided with the grooves 3 and 4 is divided into individual elements. In this division, the marking line 5 or the grooves 3 and 4 are not subjected to the roller pressurization which is usually performed by the scribe.
It is most preferable to apply a blade such as a stainless blade or a ceramic blade to and to apply a weight to the blade to divide the element. By doing in this way, a step is formed between the dicing part and the part where the element is cracked, and moreover, the force is concentrated on the part to be cracked, so not only chipping is small, but also the natural fracture surface is large. And the light extraction efficiency becomes high. Instead of the scribing line 5, a cutting line similar to that may be inserted, and in the end, a shallow groove having a thickness of 1/3 or less of the thickness of the gallium phosphide wafer is provided, and a scratch is provided on the surface or the bottom surface facing the shallow groove. It is sufficient to divide the element into individual elements at the portion where the scratch or groove is provided.

By thus forming the step and exposing the natural fracture surface widely, the light extraction efficiency of several percent to several percent is improved as compared with the element of the completely cleaved surface or the light emitting diode element of the cut fracture surface. The reason for this is not exactly known, but it is highly possible that the side surface crystal of the element is distorted by cutting and the light absorption due to crystal damage is large, while on the other hand, a perfect cleaved surface has the internal light inside. It seems that the reflection component increases. Multiple cleavage planes appear on the natural fracture surface, and in this case the light extraction efficiency is the highest. For that purpose, if grooves are made on the front or back surface and scratches are made on the other surface, cracking will occur on both surfaces even if pressure is applied. Is constrained and a natural fracture surface is obtained. On the other hand, if a thick wafer is suddenly divided by the scribe method, not only is it difficult to break into a die shape, but an unreasonable force remains in the crystal. On the other hand, if a deep groove is provided and the wafer is divided, chipping often occurs. There is also a reason in the manufacturing process that the light-absorbing crystal portion is increased due to cutting. From such assumptions and restrictions, it is possible to provide the step (groove) from the top surface or the bottom surface.

Therefore, the thickness is 300 μm, 270 μm, 2
For four types of wafers of 50 μm and 220 μm, the groove depth, workability, optical characteristics, etc. were examined. 3 and 4
Is an example of a gallium phosphide light emitting diode wafer having a thickness of 270 μm, and FIG. 3 shows the depth of the groove and the degree of chip breakage for each representative lot. It is shown that the deeper the groove, the more chips there are. ing. Further, FIG. 4 shows the relationship between the depth of the groove and the chip brightness. When the groove is deepened, that is, the natural fracture surface becomes narrow, the chip brightness gradually decreases,
It shows that the deeper the degree, the greater the amount of decrease. In the figure, there are lots of 6 mcd or more, and lots of 5 mcd or less do not have a groove of 100 μm or less. Approximately 2 /
If it is provided so that a natural fracture surface can be obtained at 3 or more,
It was said that workability was good, light was taken out, and efficiency was high.

[0011]

As described above, according to the present invention, the light extraction amount is larger than that of the light emitting diode element obtained by the division method such as the dicing method or the cleavage scribe.

[Brief description of drawings]

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

FIG. 2 is an explanatory diagram related to a method for manufacturing a light emitting diode device according to an embodiment of the present invention.

FIG. 3 is a characteristic diagram showing, for each representative lot, the depth of a groove on a wafer and the degree of chipping.

FIG. 4 is a characteristic diagram showing the relationship between the groove depth of the wafer and the chip brightness.

[Explanation of symbols]

 1 gallium phosphide wafer 2, 20 light emitting junction 13, 14 side surface 18, 19 step 28 natural fracture surface 3, 4 groove

Claims (2)

[Claims] 1. A gallium phosphorous light emitting diode device having a light emitting junction substantially parallel to a surface or a bottom surface, wherein a step is provided on a side surface thereof, and a natural fracture surface is provided at 2/3 or more of a height of the side surface. And a light emitting diode element. 2. A shallow groove having a thickness of ⅓ or less of the thickness of a gallium phosphide wafer having light emitting junctions substantially parallel to the surface or the bottom surface is provided, and the surface or the bottom surface facing the shallow groove is provided with a scratch. And a step of dividing the device into individual devices at the portion where the groove is provided.