JP2703232B2 - Light emitting diode array and method of manufacturing the same - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting diode array for an optical printer suitable for use in a line, and a method for manufacturing the same. B) Prior art In recent years, light emitting diode arrays having a large number of aligned light emitting portions have been used as optical printer heads. Among them, Japanese Patent Application Laid-Open Nos.
As shown in JP-A-2-25071, a so-called one-line type optical printer head in which light emitting diode arrays are arranged in a line over the entire length of the optical printer in the main scanning direction has become mainstream. In such an optical printer head, a light emitting diode array having a length of 5 to 10 mm is arranged in a length of 200 to 400 mm in consideration of the size of the wafer and conditions for stabilizing characteristics. The problem in this case is that the alignment pitch of the light-emitting portions (52) (52) is also predetermined at the joint (a) of the light-emitting diode arrays (50) and (50) as shown in FIG. By setting the value within the range, when the wafer is divided, it must be performed in the vicinity of the light emitting units (52) (52). Division of a wafer which is restricted in such a division position is as follows.
Scribing is performed in the cleavage direction of the compound semiconductor substrate used, and pressure is applied. However, it is difficult for the scribing direction to completely match the cleavage direction, and the direction is generally 0.001.
0.010 degree deviation, slight deviation even in linearity. At this time, the entire surface of the substrate crystal is broken at one cleavage plane, and the split surface does not become a mirror surface, but a portion that is split along the scribe line and a cleavage surface are mixed, and the surface generally follows the scribe line, but the surface is It exhibits a state like a micro mirror surface aggregate. When such cracking is performed, crystal strain is likely to occur at the center of the cracked portion, and the influence often extends to 20 to 40 μm from the edge. Therefore, if the light emitting portion (52) is provided in this portion, the light emission luminance characteristic which originally shows a light emission distribution (b) having a substantially concave shape as shown in FIG. Distribution (c),
Black shading (d) can be observed visually, or rapid deterioration occurs. These are disadvantageous because they degrade the print quality. C) Problems to be Solved by the Invention The present invention has been made in order to improve the above-mentioned point, and an LED and a method of manufacturing the same which do not cause deterioration in characteristics of a light emitting portion located near an edge of a light emitting diode array. To provide. D) Means for Solving the Problems In the present invention, at least the vicinity of the light emitting portion is a mirror surface formed by natural cleavage, and in order to obtain the same, a scribe line is not provided only near the light emitting portion. Is to provide a coating or a concave portion in the vicinity of the light emitting portion to make a scribe needle. (E) Action As a result, the division is restricted to the vicinity of the light-emitting portion, and the division is performed according to the crystal cleavage plane in the very vicinity of the light-emitting portion. Since the light-emitting portion can be divided at the position and no crystal distortion is applied to the light-emitting portion, no characteristic deterioration occurs. F) Embodiment FIG. 1 is a perspective view of a main part of a light emitting diode array according to an embodiment of the present invention. Light is emitted by selective diffusion on the surface of a growth layer of a compound semiconductor substrate (1) in which GaAsP is epitaxially grown on GaAs. Are arranged in a line, and the individual electrodes (3) (3) for supplying power to the light-emitting units (2) (2) are provided through an insulating space (4). The common electrode (5) is provided on substantially the entire back surface. The side wall (6) parallel to the row of the light-emitting portions (2) (2)... Is obtained by a scribe method or a dicing method, and thus has a surface or a rough surface like a fine mirror surface assembly. (2) Although the side wall (7) located on the extension in the alignment direction of (2) has a surface like a micro-mirror surface assembly by the scribe method, the scribe is provided only in the vicinity of the light emitting portion (2). A mirror-like natural cleavage plane (8) is obtained due to the absence of the scribe line by the needle. Such a light emitting diode array will be described more specifically including a manufacturing method. Example 1. As shown in FIG. 2 (a), a wafer (substrate of a compound semiconductor before being divided) (20) has a thickness of 280 to 380 μm and a depth of 5 to 10 μm from the surface. 22) Prepare the ones with selective diffusion. Assuming that the resolution of the optical printer head is 9.45 dots / mm and 16 dots / mm, the sizes of the light emitting parts (22) (22) are 65 μm and 40 μm on one side, respectively.
Are approximately square, and the distance between the light emitting parts (22) and (22) is 40.5
μm and 22.5 μm. However, after division, it is necessary to align them on the head substrate. Therefore, it is more preferable that the interval between the light emitting portions (22) and (22) is narrowed to about 28 μm and about 12 μm only at the portion to be scribed. Such a wafer (2
0) are provided with the individual electrodes (23) (23) and the common electrode (25), but the insulating film (24) as a mask used to form the light-emitting portions (22) (22). (twenty three)
(23) It may be used as an intervening layer for short circuit prevention. The individual electrodes (23) (23) are, for example, aluminum films, and as shown in FIGS. 2 (b) and (c), the individual electrodes (23) (23).
At the time of formation, a thin film (29) is partially formed simultaneously between the light emitting portions (22) (22)... Although the thin film (29) made of the aluminum film may be scraped with a scribe needle, it is necessary to prevent a scribe groove having a depth sufficient to break the surface of the wafer (20). Aluminum is sticky due to its material. For example, if a deposited film of 0.5 to 1.5 μm is provided, the lower part of the thin film (29) (but slightly shifted in the scribe direction) by roller pressure after scribing The lower part) is naturally cleaved to have a mirror surface. At this time thin film (29)
However, there is no problem as long as a short circuit accident or the like does not occur, and it may be connected to one of the individual electrodes (23) so that an accident does not occur even if the separation occurs. The above-mentioned insulating film (24) is a silicon nitride film having a uniform thickness selected from, for example, 0.1 to 1.0 μm, and if provided over the entire scribe region, it can be cut and broken very easily by a scribe needle. No particular problem arises. However, it may be completely removed over the entire scribe area. Embodiment 2 In the same wafer as described above, an inorganic insulating film can be used as a method of flying a scribe needle.
As shown in FIG.
1) (391)... And the other portion is an inorganic insulating film (39) on all wafer surfaces including between the light emitting portions (32) (32). Can be achieved. At this time, the inorganic insulating film (3
9) The inorganic insulating film (39) should be made of a material with good adhesion to the wafer surface, etc., or a film forming method so that the light-emitting portions (32) and (32) ... could not be scribed between the light-emitting portions (32) and (32). The inorganic insulating film (39) is preferably provided over a large area so as to be strong. For example, aluminum oxide, PSG, silicon nitride, etc.
An inorganic insulating film (39) having a thickness of 7 to 5.0 μm can be used, and these inorganic insulating films (39) are used as the light emitting portions (32) (32) ...
Is preferable because not only the mirror-like natural cleavage plane described above can be obtained on the side wall but also the light extraction efficiency can be improved. Example 3 The formation of a concave portion was also effective as a method of flying a scribe needle. For example, if the resolution of the optical printer head is 12
In the example of dot / mm, the light emitting units (42) and (42) shown in FIG.
… Are approximately 50 μm on a side, approximately square, with a spacing of 34.5 μm
m), the interval between the scribe portions is 26.5 μm, and a recess (49) having a width of 20 μm, a length of 80 μm, and a depth of about 5 μm is formed by a mesa etching method, and the scribe needle moves in a substantially central portion of the recess. did. As a result, a mirror-like natural cleavage plane (48) could be obtained only in the vicinity of the light emitting portion. In this method, in addition to a conventional diamond pointer as a scribe needle, a dicing saw can also be used as a scribe. In this case, in the above-described example, the distance between the light emitting portions of the cut portion is 70 μm, the width is 60 μm, and the depth is 20 μm. A concave portion was formed and cut with a dicing blade having a blade thickness of 50 μm.
At this time, the natural cleavage plane was not as large as that of the scribe pointer, but no crystal strain was applied to the light emitting part. In any of the above examples, the needle flying means such as the metal thin film (29), the inorganic insulating film (39), and the concave part (49) formed by the mesa etching are provided, and the shape of the edge of the needle flying means is devised. In addition, it is possible to more effectively perform the needle skipping by the needle jumping means by changing the needle moving speed of the scribe needle, and to obtain a partial lack of the scribe scribe line. Also, when dividing, a groove is provided in advance along the wide scribe direction from the back side of the wafer (the side on which the common electrode is provided), and the above-described scribe is performed on the surface of the original plate above the groove. When pressure is applied, the wafer is substantially thinned and then divided. As a result, a remarkable effect was obtained in that there was no deterioration in characteristics due to the splitting distortion of the light emitting portion in all the lots tested, and no burrs (protrusions) that hindered the equal pitch arrangement were generated. At this time, if the depth of the groove from the back surface is set so that the thickness of the remaining wafer is about 100 to 180 μm, the wafer is not undesirably broken during the operation. G) Effect of the Invention As described above, since the vicinity of the light emitting portion is a naturally cleaved surface, there is no adverse effect such as crystal distortion on the light emitting portion. In the manufacturing method, the break of the scribe line is only at the place where the needle flying means is provided. Even when the distance between the light-emitting portions is small, no positional deviation occurs, and the occurrence of burrs that hinders a uniform pitch arrangement can be prevented in a substantially thin wafer. As a result, the light emitting portion shows a luminance distribution without a large decrease in luminance, and a life approximately equal to that of the central portion can be obtained including the light emitting portions at the end portions. Even when the light emitting portions are arranged in a continuous manner, the interval between the light emitting portions can be kept substantially constant, so that the deterioration of the print quality can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a light emitting diode array according to an embodiment of the present invention, FIGS. 2 (a), (b) and (c) are main part process diagrams for explaining a manufacturing method thereof, and FIG. FIG. 4 is a plan view of a principal part of a compound semiconductor wafer for explaining another embodiment, FIG. 4 is a perspective view of a light emitting diode array of still another embodiment, and FIG. FIG. 3A is a diagram illustrating a characteristic (a) and FIG. (2) (2) ... (22) (22) ... (32) (32) ... (42)
(42) ... Light-emitting unit, (3) (3) ... (23) (23) ... (3
3) (33) ... (43) (43) ... Individual electrodes, (7) (47)
...... side wall, (8) (48) ... natural cleavage plane, (29) ... thin film, (39) ... inorganic insulating film, (49) ... recess.

Claims (1)

(57) [Claims] A plurality of light emitting portions provided in alignment with the surface, and a mirror-like natural cleavage plane only in the vicinity of the light emitting portion on the side wall located on the extension of the light emitting portion in the alignment direction, for an optical printer. Light emitting diode array. 2. A step of providing a plurality of light emitting portions aligned on the surface of the compound semiconductor substrate, and a step of providing a needle flying means such that a scribe needle does not contact the substrate surface on the surface of the substrate between predetermined light emitting portions; Scribing so as to match the cleavage direction of the substrate and passing over the needle flying means, and dividing the substrate. 3. The needle flying means is a metal thin film provided on the surface of the substrate,
3. The light according to claim 2, wherein the light is either an inorganic insulating film provided on the surface of the substrate and having a scribe hole, or a concave portion provided on the surface of the substrate by a mesa etching method. Manufacturing method of light emitting diode array for printer.