JPH04354384A - Light emitting diode array - Google Patents

Abstract

PURPOSE:To eliminate print defective by providing an edge face at the side crossing with a line of a light emitting part of a pellet at right angles with a vertical surface from a light emitting surface to a specified depth and a dicing surface which tilts in a direction wherein a pellet length is shortened. CONSTITUTION:A groove 6 is formed in a dicing region between pellets of a wafer wherein a light emitting diode is built. A pellet is divided by dicing using a dicer whose blade tilts by 5 to 10 deg.. In the process, an edge at the side of a pellet of the dicing groove 7 is positioned slightly outside an edge of the groove 6 in the groove 6. Therefore, a pellet is provided with a step part 6' whose projection is formed of a position wherein a bottom of the groove 6 is formed. Thereby, cracks are not generated in a light emitting surface when a pellet is handled and pellets do not collide each other when the pellet is mounted. Print defective can be thereby eliminated.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting diode array, and more particularly to a light emitting diode array in which a large number of light emitting parts are linearly arranged, which is used in an LED printer or the like.

0002

2. Description of the Related Art The structure and manufacturing method of a conventional light emitting diode array will be explained with reference to FIG. n-type Ga
An n-type GaAsP layer 2 is epitaxially grown on an As substrate 1, and Zn is selectively diffused into the surface of the n-type GaAsP layer 2 to form a p-type GaAsP layer 3 with a constant pitch. After that, a SiO2 layer 4 and a p-side electrode (
(not shown), and an n-side electrode 5 is formed on the back surface of the wafer. Next, the wafer is pelletized by dicing.

[0003] Incidentally, the light emitting diode array for printing used in an LED printer has a speed of, for example, 320 DPI (Dots per inch) over the length of the paper width.
; 320 dots per inch), and all of the light emitting parts must emit light uniformly, so such a light emitting diode array can be made from one pellet. is extremely difficult.

[0004] For this reason, usually a large number of pellets each having a few dozen light-emitting parts are lined up in a line to have a length equal to the width of the paper, but in this case, as shown in FIG. The light emitting parts are arranged at equal intervals even between the two.

[0005]

[Problems to be Solved by the Invention] When a long array is constructed by arranging a plurality of the above-mentioned conventional light emitting diode arrays, and assuming that the density is, for example, 320 DPI, the pitch of the light emitting parts is approximately 79 μm. If the length of the light-emitting parts is 44 μm, the distance between the light-emitting parts is only 35 μm, which is 17.5 μm per side of the pellet. Since the distance from the end of the light emitting part to the end of the pellet is thus small, extremely high accuracy is required for the dicing position. Furthermore, standards for the size of chipping during dicing are also strictly defined, resulting in a high defect rate in the dicing process.

Furthermore, in dicing, the width of the dicing groove is usually smaller at the tip of the blade, so the lower part of the pellet protrudes outward from the upper part. Moreover, since the area near the back surface of the pellet is near the tip of the blade, burrs may occur. The slope of these pellet sides,
If the burrs become large, the lower part of the pellets will collide when arranging the pellets, making it impossible to match the pitch of the light emitting parts, so those with large inclinations or burrs will also be defective.

[0007] As a means of preventing the protrusion of the lower part of the pellet due to the tilting of the sides of the pellet and the burrs mentioned above, a dicer with an inclined blade is used to dice the pellet so that the lower part of the pellet retracts inward, as shown in FIG. A method is being considered. However, when transferring or fixing the pellets, the jigs hit this dicing surface of the pellets, so with this shape, the edges of the pellet surface are extremely susceptible to chipping. If this chip reaches the light emitting part or electrode, that pellet becomes defective, and if the chip near the light emitting part does not reach the light emitting part, as shown in Figure 3, the pellet will become defective. is reflected by the chipped portion and travels upward, causing printing defects.

[0008]

[Means for Solving the Problems] The light emitting diode array of the present invention is obtained by forming grooves in advance in the dicing area, and by setting the blade of a dicing device at an angle from a plane perpendicular to the wafer surface, and performing dicing and pelletizing. It is. Therefore, in the light emitting diode array of the present invention, the end surface of the pellet on the side perpendicular to the row of light emitting parts is a perpendicular surface from the light emitting surface to a predetermined depth, and the pellet length from the predetermined depth to the back surface of the pellet is The dicing surface is inclined in the direction of shortening.

[0009]

Embodiments Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1(d) is a plan view showing one embodiment of the present invention, and FIG. 1(c) is a sectional view taken along the line A-A'. Moreover, (a) and (b) of FIG. 1 are sectional views for explaining the pelletizing process.

To create this example, first, (
As shown in a), epitaxial growth and diffusion steps are performed on an n-type GaAs substrate 1 to form an n-type GaAsP layer 2, p
A type GaAsP layer 3 is formed, and then SiO is deposited on the substrate surface.
2 4 and p-side electrode [indicated by 8 in figure (d)]
Also, an n-side electrode 5 is formed on the back surface of the substrate.

Grooves 6 with a depth of 30 μm are formed in the dicing region between the pellets of the wafer in which the light emitting diode array is formed using a mixed solution of sulfuric acid, hydrogen peroxide, and water. Next, as shown in FIG. 1(b), dicing is performed using a dicer whose blade is inclined at 5 to 10 degrees from the vertical to divide it into pellets. At this time, the edge of the dicing groove 7 on the pellet side is positioned slightly outside the edge of the groove 6 previously formed. Therefore, a stepped portion 6' is formed in the pellet, where the bottom surface of the groove 6 becomes a protrusion.

[0012] In the light emitting diode array pellets made as described above, the dicing surface is inclined, so even if there is a burr at the bottom of the pellet, there is no problem of collision between the pellets, and the dicing is performed at an angle. Nevertheless, the part that protrudes outward from the side of the pellet is not near the pellet surface, but at the stepped part 6' that was the bottom of the groove, so even if it is hit by a jig or tool, it is unlikely to cause a large chip. Even if chipping occurs, it is unlikely to have any negative effects.

Next, another embodiment of the present invention will be described. As in the previous example, a wafer on which a light emitting diode array is fabricated is prepared, and RI is applied to the dicing area.
Grooves are formed by the BE (reactive ion beam etching) method, and dicing is performed in the same manner as in the previous example to divide it into pellets.

In this example, since the RIBE method is used to form the groove, the amount of side etching can be reduced, and the position and shape of the edge of the groove can be formed with high precision, making it possible to form a higher density light emitting diode array. It becomes possible to make.

Note that dicing in the direction parallel to the light emitting diode array may be carried out in the conventional manner;
When forming grooves perpendicular to the light emitting diode rows, grooves may also be formed in advance in the parallel direction. In this case, adjacent pellets can be separated by one dicing without tilting the blade.

[0016]

Effects of the Invention As explained above, in the light emitting diode array of the present invention, the protruding portion of the end face of the pellet is located in the middle portion, so that according to the present invention, the light emitting diode array of the present invention does not emit light while the pellet is being handled. Chips will no longer occur on the surface, and pellets will no longer collide with each other when mounting them. Therefore, according to the present invention, the yield of pellets and pellet arrays can be improved.

Furthermore, LED printers will be required to have even higher dots in the future, and the present invention addresses this trend and makes it possible to create a light emitting diode array with an even higher density of light emitting parts. As such, the industrial effect is extremely large.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view and a plan view for explaining one embodiment of the present invention.

FIG. 2 is a sectional view of a conventional example.

FIG. 3 is a sectional view of a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1...n-type GaAs substrate, 2...n-type GaAsP layer, 3...p-type GaAsP layer, 4...SiO
2 layers, 5... n-side electrode, 6... groove,
6'...Step part, 7...Dicing groove, 8...p
side electrode.

Claims (1)

[Claims] Claim 1: In a light emitting diode array in which a plurality of light emitting parts are arranged at equal intervals on one pellet, the end face of the pellet on the side perpendicular to the row of light emitting parts is a perpendicular surface up to a predetermined depth from the light emitting surface. , a dicing surface that extends from the predetermined depth to the back surface of the pellet and slopes in a direction in which the pellet length becomes shorter, and the maximum value of the pellet length is obtained at the predetermined depth. .