JP2014027069A - Light emitting element array and light emitting element head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light emitting element array that keeps emission intensity intact by suppressing a flow of resin or the like to light emitting surfaces of light emitting elements even if bonding portions of the light emitting element array are coated with resin or the like.SOLUTION: A light emitting element array 1 has a plurality of light emitting elements 3 and a plurality of electrode pads 5 on a substrate 2. The plurality of light emitting elements 3 are arranged in line on one principal surface of the substrate 2. The plurality of electrode pads 5 are arranged in line along the direction of arrangement of the light emitting elements 3 on the one principal surface of the substrate 2. A first projecting part 6a is provided in at least one line along the direction of arrangement on the one principal surface of the substrate 2 between the line of the plurality of light emitting elements 3 and the line of the plurality of electrode pads 5. Both ends of the first projecting part 6a are positioned outside both ends of the line of the plurality of light emitting elements 3 and the line of the plurality of electrode pads 5.

Description

  The present invention relates to a light emitting element array and a light emitting element head.

  Conventionally, a light emitting element array in which a plurality of light emitting elements are arranged is employed as an optical element used for a light source of various exposure apparatuses and the like. For example, in the light-emitting element array described in Patent Document 1, an electrode is connected to a semiconductor layer having a light-emitting portion, and an electrode pad connected to the electrode and an external electronic component are connected by wire bonding. Then, as the arrangement density of the light emitting elements increases, secondary bonding, that is, stitch bonding is performed for bonding on the light emitting element array side. In such a light emitting element array, since the bonding area of the secondary side bonding is reduced, the bonding strength tends to be reduced. By using the light emitting element array, the wire bonding on the light emitting element array side is peeled off and the electrical connection is made. There was a problem that could not be maintained. Therefore, the present inventor has studied coating the bonding portion with a resin or the like so that the wire bonding on the light emitting element array side is not peeled off.

  However, in many light emitting element arrays with high arrangement density, the distance between the light emitting surface of the light emitting element and the electrode pad is formed short for miniaturization, so that the coated resin flows out or the solvent component of the resin oozes out. As a result, the light emitting surface of the light emitting element is contaminated, and there is a problem that the light emission intensity is lowered.

JP 2002-184805 A

  The present invention has been made in view of the above problems, and even when the bonding portion of the light emitting element array is coated with a resin or the like, the coated resin or the like is prevented from flowing out to the light emitting surface of the light emitting element, An object of the present invention is to provide a light emitting element array capable of suppressing a decrease in light emission intensity.

  The light-emitting element array of the present invention is electrically connected to a rectangular semiconductor substrate with a plurality of light-emitting elements and the light-emitting elements via metal wires and electrically to external electronic components via bonding wires. A plurality of electrode pads connected to each other, wherein the plurality of light emitting elements are arranged in a row on one main surface of the semiconductor substrate, and the plurality of electrode pads are arranged on one side of the semiconductor substrate. The light emitting elements are arranged on the main surface in rows along the arrangement direction of the light emitting elements, and the light emitting elements are arranged on one main surface of the semiconductor substrate between the plurality of light emitting element rows and the plurality of electrode pad rows. At least one row of first protrusions along the arrangement direction, and both ends of the first protrusions are positioned outside both ends of the plurality of light emitting element rows and the plurality of electrode pad rows. It is characterized by doing.

  The light-emitting element array of the present invention has a plurality of rows of the first convex portions in the above-described configuration, and the height of the first convex portions of the plurality of rows includes the light-emitting elements, the electrode pads, and the like. It is characterized by becoming low as it distances from this electrode pad in between.

  Furthermore, the light emitting element array of the present invention has a plurality of rows of the first protrusions in the above-described configuration, and the width of the first protrusions of the plurality of rows is between the light emitting elements and the electrode pads. It is characterized by becoming wider as it approaches the electrode pad.

  The light-emitting element array according to the present invention is characterized in that, in the above structure, the first convex portion has a wavy or zigzag shape along the arrangement direction of the light-emitting elements.

  Furthermore, the light emitting element array according to the present invention has the above-described configuration, wherein the second convex portion extends from each of both ends of the first convex portion toward the long side of the semiconductor substrate located on the plurality of electrode pads. It further has these.

  In the light-emitting element head according to the present invention, a plurality of light-emitting element arrays having any one of the above-described structures are arranged in a row in the long side direction of the semiconductor substrate on a substrate on which electronic components are mounted. The bonding wires are connected to each other and covered with a resin.

  According to the light emitting element array of the present invention, a plurality of light emitting elements and a light emitting element are electrically connected to the light emitting elements via metal wires and electrically connected to external electronic components via bonding wires. A plurality of electrode pads connected to each other, wherein the plurality of light emitting elements are arranged in a row on one main surface of the semiconductor substrate, and the plurality of electrode pads are arranged on the semiconductor substrate. On one main surface of the semiconductor substrate, arranged in a row along the arrangement direction of the light emitting elements, and on one main surface of the semiconductor substrate between the plurality of light emitting element columns and the plurality of electrode pad columns, There are at least one row of first protrusions along the arrangement direction of the light emitting elements, and both ends of the first protrusions are outside the ends of the plurality of light emitting element rows and the plurality of electrode pad rows. Because it is located in When the array is connected to an external electronic component with an electrode pad via wire bonding, and the electrode pad is coated with a resin such as epoxy resin or silicone resin to ensure the connection reliability of the wire bonding part, the resin As a result, it is possible to prevent the emission intensity from being lowered by covering the light emitting surface of the light emitting element by flowing out the solvent that is a resin component, so that the connection reliability of the bonding portion is high and the emission intensity is reduced. A light-emitting element array that can be suppressed can be provided.

It is a top view of the light emitting element array which concerns on one Embodiment of this invention. FIG. 2 is a cross-sectional view taken along line 1I-1I of the light emitting element array shown in FIG. It is a top view of the light emitting element head using the light emitting element array shown in FIG. It is a top view which shows the 1st modification of the light emitting element array shown in FIG. (A), (b) is sectional drawing explaining the modification of a convex part, (c), (d) is a top view explaining the modification of a convex part. It is a top view which shows the 2nd modification of the light emitting element array shown in FIG.

(Light emitting element array)
Hereinafter, examples of embodiments of the light-emitting element array and the light-emitting element head of the present invention will be described with reference to the drawings. In addition, the following examples illustrate embodiments of the present invention, and the present invention is not limited to these embodiments.

  A light emitting element array 1 shown in FIG. 1 functions as a light source in an exposure apparatus such as an optical element head incorporated in an electrophotographic apparatus such as a page printer.

  The light emitting element array 1 includes a base substrate 2, a plurality of light emitting elements 3, a plurality of electrode pads 5 connected to each of the light emitting elements 3 via metal wires 4, and a first convex portion 6a. ing.

The base substrate 2 is formed of a single crystal such as silicon (Si), gallium arsenide (GaAs), gallium phosphide (GaP), gallium nitride (GaN), sapphire (Al ₂ O ₃ ), and has a plurality of light emission. It functions as a support for the element 3. The base substrate 2 of this example is formed of a rectangular gallium arsenide (GaAs) single crystal. Further, it contains about 1 × 10 ¹⁶ to 10 ¹⁹ atoms / cm ³ of one conductivity type semiconductor impurity such as silicon (Si) and functions as a one conductivity type semiconductor. A back electrode 7 for supplying power to the light emitting element 3 is formed on the lower surface of the base substrate 2.

  The light emitting element 3 is formed of a semiconductor layer in which a one-conductivity type semiconductor layer 30 and a reverse conductivity type semiconductor layer 31 are sequentially stacked, and functions as a light source of the light emitting element array 1. The plurality of light emitting elements 3 are arranged in a row on the upper surface of the base substrate 2. In addition, although the light emitting elements 3 of this example are arranged in one row, they may be arranged in a plurality of rows.

The one-conductivity-type semiconductor layer 30 in this example is composed of an electron injection layer 30a. The electron injection layer 30a is made of, for example, aluminum gallium arsenide (AlGaAs), contains about 1 × 10 ¹⁶ to 10 ¹⁹ atoms / cm ³ of one conductivity type semiconductor impurity such as silicon (Si), and has a thickness of 0.1. It is about 2 to 0.4 μm. The composition ratio of aluminum (Al) in the electron injection layer 30b is about 0.24 to 0.5.

Since the base substrate 2 functions as a part of the one conductivity type semiconductor layer 30, the one conductivity type semiconductor layer 30 of this example includes only the electron injection layer 30 a, but the base substrate 2 is composed of sapphire (Al ₂ In the case of a non-conductive substrate such as O ₃ ), an ohmic contact layer is formed on the upper surface of the base substrate 2 for electrical connection between the one-conductivity type semiconductor layer and an external electronic component.

On the other hand, the reverse conductivity semiconductor layer 31 includes a light emitting layer 31a, a cladding layer 31b, and an ohmic contact layer 31c. The light emitting layer 31a and the cladding layer 31b are made of, for example, aluminum arsenide (AlAs) and gallium arsenide (GaAs) with different mixed crystal ratios in consideration of the electron confinement effect and the light extraction effect. In addition, a reverse conductivity type semiconductor impurity such as zinc (Zn) is contained in an amount of about 1 × 10 ¹⁶ to 10 ¹⁸ atoms / cm ³ and the thickness is about 0.2 to 0.4 μm. The ohmic contact layer 31c is made of, for example, gallium arsenide (GaAs), contains about 1 × 10 ¹⁹ to 10 ²⁰ atoms / cm ³ of a reverse conductivity type semiconductor impurity such as zinc (Zn), and has a thickness of 0 .01 to 0.1 μm.

  An insulating layer 8 is formed so as to cover the upper surface of the substrate 2 on the light emitting element 3 side and the light emitting element 3 excluding a part of the upper surface of the ohmic contact layer 31c. The insulating layer 8 is made of, for example, silicon nitride (SiN) and has a thickness of about 3000 to 50000 mm.

  A plurality of electrode pads 5 corresponding to each of the light emitting elements 3 and a plurality of metal wires 4 respectively connecting the plurality of light emitting elements 3 to the plurality of electrode pads 5 are formed on the upper surface of the insulating layer 8. The insulating layer 8 has a function of ensuring electrical insulation between the plurality of electrode pads 5 and the plurality of metal wires 4 and the semiconductor layer other than the ohmic contact layer 31 c of the substrate 2 or the light emitting element 3.

The electrical connection between the light emitting element 3 and the electrode pad 5 is such that the portion of the ohmic contact layer 31 c formed on the upper surface of the light emitting element 3 that is not covered with the insulating layer 8 and the electrode pad 5 are connected to the metal wire 4.
It is done by connecting with.

  The metal wire 4 and the plurality of electrode pads 5 are formed of a metal material such as gold (Au), aluminum (Al), or copper (Cu).

  On the upper surface of the substrate 2 positioned between the plurality of light emitting element 3 columns and the plurality of electrode pad 5 columns, the first protrusions 6 a along the arrangement direction of the light emitting element 3 columns or the electrode pad 5 columns are arranged. Is formed. The insulating layer 8 and the metal wire 4 described above are formed on the upper surface of the first convex portion 6a.

  The first convex portion 6a is formed, for example, with a height of 0.2 to 100 μm and a width in the direction from the light emitting element 3 to the electrode pad 5 of 50 to 100 μm, and both ends of the first convex portion 6a are The light emitting element 3 and the electrode pad 5 are located outside both ends of the row.

  By having such a first convex portion 6a, the light emitting element array 1 is connected to an external electronic component through the wire bonding by the electrode pad 5, and the electrode pad is used to ensure the connection reliability of the wire bonding portion. When 5 is coated with a resin such as an epoxy resin or a silicone resin, the resin flows out or the solvent that is a resin component oozes out, so that the light emission intensity is reduced by covering the light emitting surface of the light emitting element 3. Can be prevented. Here, the light emitting surface is an upper surface corresponding to the light emitting layer 30 a of the light emitting element 3, and corresponds to a region when the light emitting layer 30 a is seen through from the upper surface of the light emitting element 3.

  Next, a method for manufacturing the above-described light emitting element array 1 will be described.

First, the one-conductivity-type semiconductor layer 30 and the reverse-conductivity-type semiconductor layer 31 are formed on the upper surface of the substrate 2 by MOCVD (Metal-Organic Chemical Vapor Deposition) or MB.
E (molecular beam epitaxy) method or the like is sequentially laminated to form.

The one-conductivity-type semiconductor layer 30 and the reverse-conductivity-type semiconductor layer 31 have TMG ((CH ₃ ) ₃ Ga), TEG ((C ₂ H ₅ ) ₃ Ga, arsine, with a substrate 2 temperature of 700 to 900 ° C. (AsH ₃ ), TMA ((CH ₃ ) ₃ Al), TEA ((C ₂ H ₅ ) ₃ Al), etc. are formed as source gases, and silane (SiH ₄₎ is used as a gas for controlling the conductivity type. ), Hydrogen selenide (H ₂ Se), TMZ ((CH ₃ ) ₃ Zn) or the like is used, and hydrogen (H ₂ ) or the like is used as the carrier gas.

Next, the one conductive semiconductor layer 30 and the reverse conductive semiconductor layer 31 are patterned in an island shape so that the adjacent light emitting elements 3 are electrically separated from each other, and the first convex portion 6a is also patterned. It is formed by. Patterning is performed by a well-known photolithography method, and etching is performed by wet etching using a sulfuric acid hydrogen peroxide aqueous etching solution or dry etching using CCl ₂ F ₂ gas.

  The first convex portion 6 a is formed on the upper surface of the substrate 2 at a position corresponding to between a row of the plurality of light emitting elements 3 to be formed later and a row of the plurality of electrode pads 5. Both ends of the first convex portion 6 a are formed so as to be located outside both ends of the row of the plurality of light emitting elements 3 to be formed later and both ends of the row of the plurality of electrode pads 5.

Next, an insulating layer 8 made of silicon nitride (SiN) using silane gas (SiH ₄ ) and ammonia gas (NH ₃ ) is formed on the substrate 2 and the upper surface of the substrate 2 by plasma CVD. And so as to cover. At this time, the insulating layer 8 is not formed on a part of the ohmic contact layer 31c formed on the surface of the light emitting element 3, and electrical connection with the metal wire 4 to be formed later is made possible.

  Next, a plurality of electrode pads 5 corresponding to each of the light emitting elements 3 are formed on the upper surface of the insulating layer 8 by vapor deposition or sputtering using gold (Au), aluminum (Al), copper (Cu), or the like. A plurality of metal lines 4 for connecting the ohmic contact layer 31 c exposed on the upper surface of the electrode 3 and the electrode pads 5 corresponding to the light emitting elements 3 are formed. Similarly, the back electrode 7 is formed on the lower surface of the base substrate 2 located on the opposite side of the surface on which the light emitting element 3 is mounted. The electrode pad 5, the metal wire 4 and the back electrode 7 may be formed simultaneously.

  The light emitting element array 1 configured as described above can cause a desired light emitting element 3 to emit light by supplying electric power between the electrode pad 5 and the back electrode 7.

  In this example, the first convex portion 6a is formed by the one-conductivity-type semiconductor layer 30 and the reverse-conductivity-type semiconductor layer 31 simultaneously with the light emitting element 3, but the above-described metal wire 4 is formed on the upper surface of the insulating layer 8. Later, using a polyimide resin, an epoxy resin, or the like, patterning may be performed by a conventionally known photolithography method.

(Light emitting element head)
Next, the light emitting element head 100 shown in FIG. 2 will be described.

  In the light emitting element head 100, the plurality of light emitting element arrays 1 described above are arranged in a row on the upper surface of the substrate 110 via an adhesive 120, and function as an exposure apparatus incorporated in an electrophotographic apparatus such as a page printer. .

  The substrate 110 is formed of a ceramic substrate or an organic substrate made of glass epoxy resin, etc. Although not shown, an electrical wiring and a connection pad for electrical connection with the light emitting element array 1 and the outside are provided on the upper surface. It has been. The substrate 110 functions as a support for supporting the plurality of light emitting elements 3 and as a circuit board for electrically connecting the light emitting elements 3 and external electronic components.

  The electrode pads 5 of the light emitting element array 1 are connected to connection pads (not shown) formed on the upper surface of the substrate 110 by wires 130 by wire bonding. Then, a coating resin 140 such as an epoxy resin or a silicone resin is applied to the electrode pad 5 and the connection portion of the wire 130 connected to the electrode pad 5 to coat the wire bonding portion on the light emitting element array 1 side. A dispenser or the like may be used for applying the coating resin.

  The reason for coating the wire bonding portion on the light emitting element array 1 side with resin is that as the arrangement density of the light emitting elements 3 increases, the electrode pad 5 becomes the secondary side of wire bonding and stitch bonding is performed. This is because the connection area is reduced, so that the wire 130 is reinforced with resin so that the wire 130 is not peeled off from the electrode pad 5.

According to the light-emitting element array 1 included in the light-emitting element head 100 of this example, the row of the light-emitting elements 3 or Since the first protrusions 6a are formed along the arrangement direction of the rows of the electrode pads 5, and both ends thereof are located outside the both ends of the rows of the light emitting elements 3 and the rows of the electrode pads 5, light emission Even when the distance between the element 3 and the electrode pad 5 is short, when an epoxy resin or a silicone resin is applied onto the electrode pad 5, the applied resin flows out to the light emitting surface of the light emitting element 3 or is a solvent component contained in the resin. As a result of oozing out, the light emitting surface of the light emitting element 3 is not contaminated, and a decrease in the light emission intensity of the light emitting element 3 can be suppressed and kept relatively high. Contamination of the light emitting surface of the light emitting element 3 is suppressed because the resin that has flowed out and the solvent component that has oozed out of the resin are blocked by the first convex portion 6a, and these move to the light emitting surface side. This is because it can be prevented.

  In this example, the light emitting element 3 is connected to the connection pad of the substrate 110. However, a driving IC for driving the light emitting element 3 is further arranged on the upper surface of the substrate 110 to drive the electrode pad of the light emitting element 3. You may connect with the electrode pad of IC.

  Although specific embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications can be made without departing from the scope of the present invention.

  For example, although the first protrusions 6a in this example are formed in one row, they may be formed in a plurality of rows as in the first modification of this example shown in FIG. When the first protrusions 6 are arranged in a plurality of rows, the resin that has flowed out and the solvent component that has oozed out of the resin cannot be blocked by the first protrusions 6 a that are located closest to the electrode pad 5. This is because the next first convex portion 6a can be prevented from moving to the light emitting surface of the light emitting element 3 by blocking the resin that has flowed out and the solvent component that has oozed out of the resin.

  Further, as described above, in the case of having a plurality of rows of first protrusions 6a, as shown in FIG. 5A, the first protrusions are directed from the electrode pad 5 toward the light emitting element 3. You may make the height of the part 6a low. With such a structure, the wetting effect of the resin that has flowed out and the solvent component that has oozed out of the resin is enhanced, and the light emitted from the light emitting element 3 is reflected by the first convex portion 6a to become stray light. Can be suppressed. The insulating layer 8 and the metal wire 4 are formed on the first convex portion 6a. The insulating layer 8 and the metal wire 4 are formed by a plasma CVD method, a vapor deposition method, a sputtering method, or the like. Considering the ease of formation of the first convex portion 6a, it is advantageous that the height of the first convex portion 6a is lower. Therefore, the flow of the resin and the seepage of the solvent component from the resin are relatively suppressed. By reducing the first protrusion 6 on the light emitting element 3 side, the reliability of the connection of the metal wire 4 to the light emitting element 3 can be improved while preventing the light emitting surface of the light emitting element 3 from being contaminated. .

  Furthermore, as described above, when the plurality of first protrusions 6a are arranged, as shown in FIG. 5B, the first protrusions are directed from the light emitting element 3 toward the electrode pad 5. The width of 6a may be widened. This is because the flow-out resin is blocked by the wide first convex portion 6a on the side close to the electrode pad 5, and the amount of the solvent component exuded from the resin is relatively small. The projection 6a is used to block the projection. Since the distance between the row of the light emitting elements 3 and the row of the electrode pads 5 is short, the width of the first convex portion 6a is increased as the electrode pad 5 is approached, thereby preventing the resin from flowing out and the solvent component from the resin. It is a structure that efficiently prevents bleeding.

  As a matter of course, it is possible to combine the relationship between the height and width of the first convex portion 6a.

  In addition, the first convex portion 6a is linear in this example, but may be wavy as shown in FIG. 5C, or may be zigzag as shown in FIG. 5D. It may be a shape. The wavy shape and the zigzag shape referred to here represent the shape of the first convex portion 6 a in the plan view of the substrate 2. By making the first convex portion 6 wavy or zigzag-shaped, the volume of the first convex portion 6a that blocks the resin that has flowed out and the solvent component that has oozed out of the resin is increased. This is because it becomes higher.

  Further, as in the second modification of the present example shown in FIG. 6, the both ends of the first protrusions 6a along the row of the light emitting elements 3 are directed in the long side direction of the semiconductor substrate 2 located on the electrode pad 5 side. You may further have the 2nd convex part 6b extended. With such a configuration, it is possible to prevent the resin that has flowed out from flowing into the gap between the adjacent light emitting element arrays 1, and thus the mounting accuracy of the light emitting element array 1 can be increased. This is because when the coating resin 140 flows into the gap between the light emitting element arrays 1, a stress that widens the gap between the light emitting element arrays 1 is generated due to expansion due to the hardening of the coating resin 140. This is because the position accuracy of 1 is deteriorated.

DESCRIPTION OF SYMBOLS 1 Light emitting element array 2 Base substrate 3 Light emitting element 4 Metal line 5 Electrode pad 6a 1st convex part 6b 2nd convex part 7 Back surface electrode 8 Insulating layer 30 One conductivity type semiconductor layer 30a Electron injection layer 31 Reverse conductivity type semiconductor Layer 31a Light emitting layer 31b Clad layer 31c Ohmic contact layer 100 Light emitting element head 110 Substrate 120 Adhesive 130 Wire 140 Coating resin

Claims (6)

A plurality of light emitting elements on a rectangular semiconductor substrate, and a plurality of electrode pads electrically connected to the light emitting elements via metal wires and electrically connected to external electronic components via bonding wires; A light emitting device array comprising:
The plurality of light emitting elements are arranged in a row on one main surface of the semiconductor substrate,
The plurality of electrode pads are arranged in a row along the arrangement direction of the light emitting elements on one main surface of the semiconductor substrate,
At least one first protrusion along the arrangement direction of the light emitting elements is provided on one main surface of the semiconductor substrate between the plurality of light emitting element rows and the plurality of electrode pad rows;
The light emitting element array according to claim 1, wherein both ends of the first convex portion are positioned outside both ends of the plurality of light emitting element rows and the plurality of electrode pad rows.   The first protrusions have a plurality of rows, and the height of the first protrusions in the rows decreases as the distance from the electrode pad increases between the light emitting element and the electrode pad. The light-emitting element array according to claim 1.   The first protrusions have a plurality of rows, and the width of the first protrusions of the plurality of rows becomes wider between the light emitting element and the electrode pad as it approaches the electrode pad. The light-emitting element array according to claim 1, wherein the light-emitting element array is a light-emitting element array.   4. The light emitting element array according to claim 1, wherein a shape of the first convex portion along the arrangement direction of the light emitting elements is a wave shape or a zigzag shape. 5.   5. The apparatus according to claim 1, further comprising a second protrusion extending from each of both ends of the first protrusion toward a long side of the semiconductor substrate positioned on the plurality of electrode pads. The light-emitting element array according to any one of the above.   A plurality of light emitting element arrays according to any one of claims 1 to 5 are arranged in a row in a long side direction of the semiconductor substrate on a substrate on which electronic components are mounted, and the plurality of electrode pads are A light-emitting element head, wherein the bonding wires are connected to each other and covered with a resin.

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