JP2013115246A - Light-emitting element array and light-emitting element head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-emitting element array capable of preventing resin and the like from flowing out over light-emitting surfaces of light-emitting elements to thereby suppress deterioration in emission intensity, even when a bonding part of the light-emitting element array is coated with the resin and the like.SOLUTION: A light-emitting element array 1 has, on a substrate 2, a plurality of light-emitting elements 3 and a plurality of electrode pads 5. The plurality of light-emitting elements 3 are arranged in a row on one principle surface of the substrate 2, and the plurality of electrode pads 5 are arranged in a row in the alignment direction of the light-emitting elements 3 on one principle surface of the light-emitting element array 1. Between the row of the plurality of light-emitting elements 3 and the row of the plurality of electrode pads 5 on the one principle surface of the substrate 2, the light-emitting element array 1 has at least one line of a first recess 6a which extends in the alignment direction. Both ends of the first recess 6a are located on outer sides of both ends of the row of the plurality of light-emitting elements 3 and the row 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, electrodes are connected to a semiconductor layer having a light-emitting portion, and electrode pads connected to the electrodes and external electronic components 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 the light emitting element array. One main surface is arranged in a row along the arrangement direction of the light emitting elements, and the one main surface of the semiconductor substrate between the plurality of light emitting element rows and the plurality of electrode pad rows is arranged in the arrangement direction. At least one row of first recesses along the first and second ends, and both ends of the first recesses are positioned outside both ends of the plurality of light emitting element rows and the plurality of electrode pad rows. To do.

  Further, in the above configuration, the first recesses are provided in a plurality of rows, and the depths of the first recesses in the rows are shallower as the distance from the electrode pad is increased between the light emitting element and the electrode pad. It is characterized by becoming.

Further, in the above configuration, the first recesses are provided in a plurality of rows, and the widths of the first recesses in the rows increase as the electrode pads are approached between the light emitting element and the electrode pads. It is characterized by.

  In the above structure, the first recess is wavy or zigzag-shaped.

  Further, in the above configuration, the semiconductor device further includes a second recess extending from each of both ends of the first recess toward the long side of the semiconductor substrate located on the plurality of electrode pads.

  In addition, a plurality of light emitting element arrays having any one of the above-described configurations are arranged in a row on a substrate on which electronic components are mounted, and the plurality of electrode pads are respectively covered with a resin while the bonding wires are connected thereto. A light-emitting element head is also provided.

  According to the light emitting element array of the present invention, a light emitting element array having a plurality of light emitting elements and a plurality of electrode pads on a substrate, wherein the plurality of light emitting elements are arranged in a row on one main surface of the substrate. The plurality of electrode pads are arranged in a line along the arrangement direction of the light emitting elements on one main surface of the light emitting element array, and the plurality of light emitting element rows and the plurality of electrode pad rows At least one row of recesses extending in the arrangement direction on one main surface of the substrate between the two ends of the recesses, and both ends of the recesses are longer than both ends of the plurality of light emitting element rows and the plurality of electrode pad rows. Since it is located outside, the light emitting element array is connected to an external electronic component by an electrode pad through wire bonding, and the electrode pad is attached to an epoxy resin or a silica to ensure the connection reliability of the wire bonding portion. When coated with a resin such as a resin, the resin flows out or the solvent that is a component of the resin oozes out, so that it is possible to prevent the emission intensity from being reduced by covering the light emitting surface of the light emitting element. It is possible to provide a light emitting element array which has high connection reliability of the bonding portion and can suppress a decrease in light emission intensity.

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 recessed part, (c), (d) is a top view explaining the modification of a recessed 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, 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 recess 6a. Yes.

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 a plurality of light emission. It functions as a support for the element 3. Note that the base substrate 2 of the present embodiment 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 the present embodiment are arranged in one row, they may be arranged in a plurality of rows.

The one-conductivity-type semiconductor layer 30 of this embodiment 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 the present embodiment is composed of only the electron injection layer 30a. _In the case of a non-conductive substrate such as ₂ O ₃ ), an ohmic contact layer is formed on the upper surface of the base substrate 2 in order to make 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 is connected to the electrode pad 5 by the metal wire 4. Is done.

  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, there are first recesses 6 a along the arrangement direction of the light emitting element 3 columns or the electrode pad 5 columns. Is formed. The insulating layer 8 and the metal wire 4 described above are formed on the upper surface of the first recess 6a.

  The first recess 6a is formed, for example, with a depth of 50 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 recess 6a are connected to the light emitting element 3. And the electrode pads 5 are located outside both ends in the row.

  By having such a first recess 6a, the light-emitting element array 1 is connected to an external electronic component via an electrode pad 5 via wire bonding, and the electrode pad 5 is secured in order to ensure the connection reliability of the wire bonding portion. When the resin 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 to prevent the light emission intensity from being lowered by covering the light emitting surface of the light emitting element 3 it can. 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-conductivity-type semiconductor layer 30 and the reverse-conductivity-type semiconductor layer 31 are patterned in an island shape so that the adjacent light emitting elements 3 are electrically separated from each other. 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.

Next, on the upper surface of the substrate 2, the first recess 6 a is formed with a CO ₂ laser, a YAG laser at a position corresponding to a space between the row of the plurality of light emitting elements 3 to be formed later and the row of the electrode pads 5. Or by excimer laser. Both ends of the first recess 6 a are formed so as to be positioned outside both ends of the plurality of light emitting element 3 columns to be formed later and both ends of the plurality of electrode pad 5 columns. In the present embodiment, the first recess 6a is formed by laser processing. However, the first recess 6a may be performed by wet etching using the above-described sulfuric acid hydrogen peroxide aqueous etching solution, dry etching using CCl ₂ F ₂ gas, or the like. . In addition, when forming the 1st recessed part 6a by an etching, you may carry out simultaneously with the process of isolate | separating the above-mentioned adjacent light emitting elements 3 mutually.

Next, silane gas (SiH ₄ ) and ammonia gas (NH ₃ ) are formed by plasma CVD.
The insulating layer 8 made of silicon nitride (SiN) is formed so as to cover the substrate 2 and the light emitting element 3 formed on the upper surface of the substrate 2. 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.

(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 the present embodiment, the row of the light emitting elements 3 is disposed on the upper surface of the substrate 2 positioned between the row of the plurality of light emitting elements 3 and the row of the plurality of electrode pads 5. Alternatively, the first recesses 6 a are formed along the arrangement direction of the rows of the electrode pads 5, and both ends thereof are located outside both ends of the rows of the light emitting elements 3 and the rows of the electrode pads 5. 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 accumulated in the first recess 6a, so that they move toward the light emitting surface. This is because it can be prevented.

  In the present embodiment, the light emitting element 3 is connected to the electrode 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, and the electrode pad of the light emitting element 3 The electrode pad of the driving IC may be connected.

  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 recesses 6a in the present embodiment are formed in one row, they may be formed in a plurality of rows as in the first modification of the present embodiment shown in FIG. By arranging the first recesses 6 in a plurality of rows, the resin that has flowed out or the solvent component that has oozed out of the resin cannot be accommodated in the first recess 6a that is positioned closest to the electrode pad 5 side. This is because it is possible to prevent the first concave portion 6a from flowing into the light emitting surface of the light emitting element 3 by containing 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 the first recesses 6a, as shown in FIG. 5A, the first recesses 6a are directed from the electrode pad 5 toward the light emitting element 3. The depth of may be reduced. By setting it as such a structure, the wetting effect of the resin which flowed out and the solvent component which oozed out from resin can be heightened. In addition, the insulating layer 8 and the metal wire 4 are formed in the first recess 6a, but 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 in the concave portion 6a, it is advantageous that the depth of the first concave portion 6a is shallow. Therefore, the outflow of the resin and the seepage of the solvent component from the resin are relatively suppressed. By reducing the depth of the first recess 6 on the light emitting element 3 side, it is possible to improve the connection reliability of the metal wire 4 to the light emitting element 3 while preventing contamination of the light emitting surface of the light emitting element 3.

  Further, as described above, in the case of having a plurality of rows of the first recesses 6a, as shown in FIG. 5B, the first recesses 6a extend from the light emitting element 3 toward the electrode pad 5. The width may be widened. This is because the resin that has flowed out is accommodated in the first concave portion 6a that is wide on the side close to the electrode pad 5, and the amount of the solvent component that has oozed out from the resin is relatively small. It accommodates in the recessed part 6a. 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 recess 6a is increased as the distance from the electrode pad 5 is increased, thereby preventing the resin from flowing out and bleeding of the solvent component from the resin. It is a structure that efficiently prevents the sticking out.

  Of course, it is also possible to combine the relationship between the depth and width of the first recess 6a.

  In addition, the first recess 6a is linear in this embodiment, but may be wavy as shown in FIG. 5 (c), or may be zigzag as shown in FIG. 5 (d). It may be a shape. The wavy shape and the zigzag shape referred to here represent the shape of the first recess 6 a in the plan view of the substrate 2. By making the first concave portion 6 corrugated or zigzag, the volume of the first concave portion 6a that accommodates 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 embodiment shown in FIG. 6, the both ends of the first recesses 6 a 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. It may further have a second recess 6b that extends. 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 wire 5 Electrode pad 6a 1st recessed part 6b 2nd recessed 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 Cladding 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 light emitting element array,
At least one first recess along the arrangement direction 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, wherein both ends of the first recess are located outside both ends of the plurality of light emitting element rows and the plurality of electrode pad rows.   The first recesses have a plurality of rows, and the depths of the first recesses in the rows become shallower 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.   A plurality of rows of the first recesses are provided, and the width of the first recesses of the plurality of rows becomes wider between the light emitting element and the electrode pad as the electrode pad is approached. The light emitting element array according to claim 1 or 2.   4. The light-emitting element array according to claim 1, wherein the first recess has a wave shape or a zigzag shape. 5.   5. The semiconductor device according to claim 1, further comprising a second recess extending from each of both ends of the first recess toward the long side of the semiconductor substrate located on the plurality of electrode pads. 2. The light emitting element array according to item 1.   A plurality of light emitting element arrays according to any one of claims 1 to 5 are arranged in a row on a substrate on which electronic components are mounted, and the plurality of electrode pads are connected to the bonding wires, respectively. And a light-emitting element head that is covered with resin.

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