JP4126454B2 - LED array - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an LED array, and more particularly to an LED array used for an exposure light source of a photosensitive drum for a page printer.
[0002]
[Prior art]
The basic configuration of the LED array is formed by arranging a plurality of light emitting elements in which one conductive semiconductor layer, a reverse conductive semiconductor layer, and an electrode are sequentially stacked, and a light emitting region of the reverse conductive semiconductor layer. The portion is covered with a light-transmitting electrical insulating film such as SiNx, and further, the portion other than the light emitting region of the reverse conductivity type semiconductor layer is covered with a light-transmitting transparent synthetic resin layer.
[0003]
A specific example of the LED array having such a basic configuration will be described.
A conventional LED array is shown in FIGS.
FIG. 6 is a plan view of the LED array, and FIG. 7 is a sectional view thereof.
[0004]
Reference numeral 21 denotes a single crystal substrate. On the single crystal substrate 21, 22 is a one-conductivity-type semiconductor layer, 23 is a reverse-conductivity-type semiconductor layer, 24 is an individual electrode, 25 is a common electrode, and 26 is a protection made of a silicon nitride film or the like. It is an insulating film as a film.
[0005]
A single-conductivity-type semiconductor layer 22 and a reverse-conductivity-type semiconductor layer 23 are sequentially stacked on the single crystal substrate 21 for each light-emitting element. In the stack, the area of the single-conductivity-type semiconductor layer 22 is the reverse-conductivity type. The area is larger than the area of the semiconductor layer 23.
[0006]
An insulating film 26 is covered on the one-conductivity-type semiconductor layer 22, and the common electrode 25 (25a, 25b) is connected to the exposed portion.
[0007]
Also, the reverse conductivity type semiconductor layer 23 is also covered with an insulating film 26, and an individual electrode 24 is connected to the exposed portion.
[0008]
Further, as shown in FIG. 6, the common electrode 25 (25a, 25b) is provided by being divided into two groups so as to belong to a different group for each adjacent light emitting element (each island-like semiconductor layer 22, 23). Adjacent light emitting elements (island-like semiconductor layers 22, 23) are connected to the same individual electrode 24.
[0009]
In this light emitting diode array structure, each light emitting element can be made to emit light selectively by selecting a combination of the individual electrode 24 and the common electrode 25 (25a, 25b) and passing a current.
[0010]
[Problems to be solved by the invention]
In recent years, with respect to LED arrays, there is a need in the market to increase the density of light-emitting elements and to reduce the size thereof. However, in the LED array having the above-described configuration, the number of electrode pads that are external connection points is further increased. It has been difficult to reduce, to further reduce the size of the connection electrode with the external circuit, or to further reduce the chip size.
[0011]
Therefore, it has been impossible to sufficiently meet the market needs for increasing the density of light emitting elements and reducing the size of LED arrays.
[0012]
In order to solve this problem, an LED array having a multilayer electrode structure in which matrix wiring electrodes are provided via an interlayer insulating film has been proposed (see Japanese Patent Laid-Open Nos. 9-277592 and 11-40842).
[0013]
However, even with this proposed LED array, the formation of individual electrodes for each light emitting diode and the formation of matrix wiring for dividing the light emitting diodes into groups and selecting them one by one from each group are performed twice. However, through the process of electrically separating each through an insulating film or the like, the multilayer electrode structure complicates the manufacturing process, thereby reducing the manufacturing yield and increasing the manufacturing cost.
[0014]
In order to solve such a problem, the present inventor has proposed a technique for simplifying the process by forming the matrix wiring in one time in the LED array disclosed in Japanese Patent Application Laid-Open No. 2000-76437.
[0015]
According to the publication, for each light emitting element group, an electrode pad formed in common for each one electrode of the light emitting elements is disposed, and the other electrode in the extending portion of each light emitting element in the light emitting element group The other electrode pads are formed in common for both the other electrodes with the same electrode interval between the light emitting element electrodes of one light emitting element group and the electrode interval of the light emitting element of the other light emitting element group. Is arranged.
[0016]
Thus, by arranging the electrode pad formed in common for the plurality of one electrode and further arranging the other electrode pad formed in common for the plurality of other electrodes, the number of electrode pads is reduced. The arrangement area is reduced, and as a result, the density of the light emitting elements and the size of the LED array are reduced.
[0017]
Further, according to the LED array having the above configuration, the number of processes is reduced and the interlayer insulation is reduced as compared with the LED array having the multilayer electrode structure proposed in Japanese Patent Laid-Open Nos. 9-277592 and 11-40842. By not using a multilayer electrode structure with a film interposed therebetween, the manufacturing cost was reduced, and an LED array in which the density and size of the light emitting elements were achieved was obtained.
[0018]
However, according to the LED array disclosed in Japanese Patent Application Laid-Open No. 2000-76437, when an insulating film is coated on the LED array, an insulating film disposed on the reverse conductive type semiconductor of each light emitting element and an insulating film disposed on the other side By forming the film with the same material at the same time, the light transmission characteristics of both are the same, so that the light emitted from the upper part of the reverse conductivity type semiconductor is reflected as a stray light to the adjacent light emitter. As a result, the MTF of the LED array was lowered, the printing quality was lowered, and the quality of the LED head could not be stabilized.
[0019]
Further, according to each of the LED heads described, the light emitting region portion of the reverse conductivity type semiconductor layer is covered with a light transmissive electrical insulating film such as SiNx, and further, the light emitting region other than the light emission region of the reverse conductivity type semiconductor layer is covered. The problem is that stray light is generated inside the light-transmitting transparent synthetic resin layer by covering the portion with a light-transmitting transparent synthetic resin layer, thereby reducing the quality and reliability of light emission. was there.
[0020]
An object of the present invention has been completed in view of the above description, and an object of the present invention is to provide an LED array in which such stray light is reduced or eliminated.
[0021]
Another object of the present invention is to provide an LED array that does not increase the number of processes, does not use a multilayer electrode structure with an interlayer insulating film, reduces the manufacturing cost, and achieves higher density and smaller size of light emitting elements. Is to provide.
[0022]
Still another object of the present invention is not to cause an electrical short-circuit failure in wire bonding, which is an external connection process of the LED array, to achieve cost reduction by further downsizing, to improve the MTF of the LED array, and to improve the print quality. It is an object of the present invention to provide an LED array with improved performance.
[0023]
[Means for Solving the Problems]
LED arrays of the present invention is formed by sequentially laminating the at least one conductive type semiconductor layer and the opposite conductivity type semiconductor layer electrode light-emitting elements are a plurality arranged on a substrate, the light from the light-emitting region of the upper surface of the light emitting element The light-emitting element has at least a part of the light-emitting layer constituting the reverse-conductivity-type semiconductor layer and at least a part of the one-conductivity-type semiconductor layer in a portion other than the light-emitting region on the upper surface. The light emitting element has at least a region including the slope covered with a light-transmitting electrical insulating film, and a portion covering the slope of the electrical insulating film includes: A light- shielding synthetic resin layer is provided so as to cover the entire slope including the end face of the light emitting layer .
[0024]
In the LED array of the present invention, the light-shielding synthetic resin layer may be one in which a dye is contained in a synthetic resin material. In this case, the synthetic resin material is preferably polyimide. In addition, the electrical insulating film may cover an upper surface substantially parallel to the inclined surfaces of the plurality of light emitting elements and the substrate surface of the reverse conductivity type semiconductor layer. The light emitting region is in a range of an upper surface substantially parallel to the substrate surface of the reverse conductivity type semiconductor layer, and the light-shielding synthetic resin layer covers the electrical insulating film over the entire slope. It is also preferable.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
As described above, the basic structure of the LED array of the present invention is such that at least a part of the light emitting region of the reverse conductivity type semiconductor layer is covered with a light-transmitting electrical insulating film, and further, other than the light emission region of the reverse conductivity type semiconductor layer. This part is covered with a light-shielding synthetic resin layer, and the present invention is an LED array including such a configuration, and an example thereof will be described below in detail with reference to the accompanying drawings.
[0026]
1 to 5 show an embodiment of the LED array of the present invention.
1 is a plan view of an enlarged main portion of the LED array, FIG. 2 is a cross-sectional view taken along the line VV ′ shown in FIG. 1, FIG. 3 is a cross-sectional view taken along the line hh ′ shown in FIG. It is a top view of each light emitting element. In FIGS. 2 and 3, V, V ′, h, and h ′ are clearly indicated as reference numerals, and directions of the cross-sectional views are shown. FIG. 5 is a plan view of the main part of another LED array.
[0027]
Reference numeral 1 denotes a single crystal substrate. On this single crystal substrate 1, 2 is a one-conductivity-type semiconductor layer, 3 is a reverse-conductivity-type semiconductor layer, 4 is an individual electrode that is the one electrode, and 5 is a common that is the other electrode. The electrodes 6 and 12 are insulating films as protective films made of an organic resin film or the like.
[0028]
8 and 10 (10a, 10b) are electrode pads for external connection.
[0029]
A single conductive semiconductor layer 2 and a reverse conductive semiconductor layer 3 are sequentially stacked on the single crystal substrate 1 for each light emitting element. In the stack, the area of the single conductive semiconductor layer 2 is a reverse conductive type. The extended portion 7 made of the same material as that of the one-conductivity-type semiconductor layer 2 is provided by pulling out the one-conductivity-type semiconductor layer 2 so as to be larger than the area of the semiconductor layer 3.
[0030]
Further, as shown in FIG. 2, an organic material such as polyimide synthetic resin or silicon nitride (SiNx), silicon oxide (SiO2), or the like, which is the light-transmissive electrical insulating film, is formed on the one conductive type semiconductor layer 2. Insulating film 6 made of an inorganic material is covered, and common electrode 5 (5a, 5b) is connected to the exposed portion to provide insulating film 6 and common electrode 5 on extension portion 7. In parallel.
[0031]
Further, a part of the light emitting region A of the reverse conductivity type semiconductor layer 3 is covered with an insulating film 6, and an individual electrode 4 is connected to the exposed portion. The protective film 12 which is the light-shielding synthetic resin layer covers the reverse conductive semiconductor layer 3 and the electrode pads 8 and 10 for external connection in a partially exposed form.
[0032]
The protective film 12 is formed by covering a portion other than the light emitting region A of the reverse conductivity type semiconductor layer 3.
[0033]
Next, each member will be described in detail.
When the single crystal substrate 1 is made of a semiconductor substrate and is composed of a high resistance silicon single crystal, a substrate with the (100) plane turned off by 2 to 7 degrees in the <011> direction is preferable.
[0034]
The one conductivity type semiconductor layer 2 includes a buffer layer 2a, an ohmic contact layer 2b, and an electron injection layer 2c.
[0035]
The buffer layer 2a and the ohmic contact layer 2b are formed of gallium arsenide or the like, and the electron injection layer 2c is formed of aluminum gallium arsenide or the like. The ohmic contact layer 2b contains about 1 × 10 ¹⁷ to 10 ¹⁹ atoms (atom) / cm ³ of one conductivity type semiconductor impurity such as silicon, and the electron injection layer 2c contains about one conductivity type semiconductor impurity such as silicon. To do.
[0036]
The buffer layer 2a is provided in order to prevent misfit dislocation based on mismatch of lattice constants between the single crystal substrate 1 and the semiconductor layer, and contains 1 × 10 ¹⁶ to 10 ¹⁹ atoms / cm ^{3 of} semiconductor impurities.
[0037]
The buffer layer 2a is formed to a thickness of about 2 to 4 μm, the ohmic contact layer 2b is formed to a thickness of about 0.1 to 3.0 μm, and the electron injection layer 2c is formed to a thickness of about 0.2 to 0.4 μm. Is done.
[0038]
The reverse conductivity type semiconductor layer 3 includes a light emitting layer 3a, a cladding layer 3b, and another ohmic contact layer 3c.
[0039]
The light emitting layer 3a and the cladding layer 3b are made of aluminum gallium arsenide, and the ohmic contact layer 3c is made of gallium arsenide.
[0040]
The light emitting layer 3a, the clad layer 3b, and the ohmic contact layer 3c have a mixed crystal ratio of aluminum arsenide (AlAs) and gallium arsenide (GaAs) between the layers in consideration of the electron confinement effect and the light extraction effect. Make it different.
[0041]
The light emitting layer 3a and the cladding layer 3b contain about 1 × 10 ¹⁶ to 10 ²¹ atoms / cm ³ of reverse conductivity type semiconductor impurities such as zinc (Zn), and the ohmic contact layer 3c contains 1 of reverse conductivity type semiconductor impurities such as zinc. × 10 ¹⁹ to 10 ²¹ atoms / cm ³
[0042]
The light emitting layer 3a and the clad layer 3b are formed to a thickness of about 0.2 to 0.4 μm, and the film thickness d of the ohmic contact layer 3c is about film thickness d> (0.15 μm−ohmic contact layer film thickness). Formed in thickness.
[0043]
The insulating film 6 is made of, for example, silicon nitride and is formed with a thickness of about 2000 mm.
[0044]
The individual electrode 4 and the common electrode 5 (5a, 5b, 5c, 5d) are made of gold / chromium (Au / Cr) or the like and are formed with a thickness of about 1 μm.
[0045]
Each light emitting element is configured as described above. Next, an electrode structure for each light emitting element is shown in FIGS.
[0046]
A common electrode pad 8 is provided for the individual electrode 4 of each light emitting element, a light emitting element group 9 corresponding to each electrode pad 8 is provided, and the one light emitting element group and the other light emitting element group are provided. Are alternately arranged, whereby a plurality of light emitting element groups 9 are arranged in a line.
[0047]
Further, the electrode interval x reaching the common electrode 5 (5a, 5b, 5c, 5d) in the extending portion 7 of each light emitting element in the light emitting element group 9 is different, and the electrode interval of the light emitting elements in one light emitting element group 9 is different. In addition, the other electrode pads 10 formed in common with respect to both other electrodes are disposed with the same electrode spacing of the light emitting elements of the other light emitting element group 9.
[0048]
Then, in order to energize the common electrode 5 of each light emitting element having the same electrode interval x, the connection line 11 (11a, 11b, 11c, 11d) is provided so as to straddle the insulating film 6 on the extending portion 7. The light emitting elements are formed in parallel with the array lines.
[0049]
Further, with respect to one light emitting element group and the adjacent light emitting element groups 9 and 9 as the other light emitting element group, the individual electrode intervals x in the light emitting element group 9 may be increased or decreased in order of arrangement. Thus, a symmetrical electrode spacing pattern is used.
[0050]
Next, in FIG. 5, a 128-bit (bit) LED array is shown by changing the electrode spacing x in four ways.
[0051]
The electrode having the shortest electrode interval x is designated as X11, which is designated as the light emitting element at the end, sequentially designated as X21, X31, X41,..., X4n, X3n, X2n, X1n,.
[0052]
By dividing 128 bits into 4 groups and 32 groups (32 light emitting element groups 9), n = 1 to 32.
[0053]
Assuming that each light emitting element group 9 is a group G1, G2,... Gm, the light emitting elements having the electrode interval X11 in the group G1 and the light emitting elements having the electrode interval X12 in the group G2 are connected by the connecting line 11a. It is connected to a light emitting element having an electrode interval X1n.
[0054]
A light emitting element having an electrode interval X21 in the group G1, a light emitting element having an electrode interval X22 in the group G2, and a light emitting element having an electrode interval X2n in the group Gm are connected by a connection line 11b.
[0055]
Similarly, the light emitting element with the electrode interval X31 in the group G1, the light emitting element with the electrode interval X32 in the group G2, and the light emitting element with the electrode interval X3n in the group Gm are connected by the connection line 11c.
[0056]
A light emitting element having an electrode interval X41 in the group G1, a light emitting element having an electrode interval X42 in the group G2, and a light emitting element having an electrode interval X4n in the group Gm are connected by a connecting line 11d.
[0057]
Then, by selectively applying a voltage between the electrode pads 8 provided in each light emitting element group and the other grouped electrode pads 10, a current can be passed to a predetermined light emitting element. The element is caused to emit light.
[0058]
Thus, according to the LED array of the present invention, a common electrode pad 8 is provided for each light emitting element group 9 (group G1, G2,... Gm...), And the light emitting element group 9 (group G1,. G2,... Gm, and so on), the electrode spacing x of each light emitting element is different, and the electrode spacing x of the light emitting elements of one light emitting element group and the electrode spacing x of the light emitting elements of the other light emitting element group are the same, Since the electrode pads 10 formed in common for both the common electrodes 5 are arranged, the number of electrode pads is reduced, and the arrangement area is reduced, thereby increasing the density of the light emitting elements and the LED array. Miniaturization is achieved.
[0059]
In the present invention, the protective film 12 is formed on the surface, and at the same time, at least a part of the electrode pads 8 and 12 for connection with an external circuit and a part of the light emitting region A of the reverse conductivity type semiconductor layer 3 are formed on the insulating film 6. And the individual electrode 4 is connected to the exposed portion.
[0060]
About the insulating film 6, it is good to set the film thickness d so that reflection may be prevented.
[0061]
The conditions for this may be as follows.
[0062]
N1: Refractive index of the insulating film 6, d: Film thickness of the insulating film 6, m: Integer, λ: Light emission wavelength of the light emitting element, N2: GaAs material of the one-conductivity-type semiconductor layer 2 and the reverse-conductivity-type semiconductor layer 3 In the refractive index, the antireflection condition is preferably (N1) d = (1/4 + m / 2) λ, and further (N1) = √ (N2).
[0063]
In addition, for the protective film 12, a dye may be contained in a synthetic resin material such as polyimide in order to make it light-shielding, and a black pigment may be contained as such a dye. For example, molybdenum disulfide, graphite, and Carbon blacks such as acetylene black, ketjen black and furnace black, metal oxides such as magnetite cobalt oxide, copper oxide and chromium oxide, composite metal oxides such as copper oxide-chromium oxide-iron oxide, titanium black, etc. There is.
[0064]
The insulating film 6 and the protective film 12 are covered and designed to have an optimal optical transmittance according to the wavelength of the LED array. In the protective film 12, the optical transmittance is relative to the wavelength of the LED array. Is designed to be the lowest so that the stray light can be reduced, and as a result, an LED array with improved MTF can be realized.
[0065]
For example, when the insulating film 6 is made of a SiNx film, the protective film 12 is made of an organic resin film, and the wavelength of the LED is 740 nm, the optimum transmittance is 100%. On the other hand, the thickness and refractive index of the insulating film 6 are designed so that the light transmittance is close to 100%. For example, the thickness of the insulating film 6 made of SiNx (refractive index = 1.88) is preferably about 3100A.
[0066]
Further, according to the LED array of this example, the electrode pads formed in common to the respective one electrodes of the light emitting elements are arranged for each light emitting element group as in the above configuration, In the extending part of each light emitting element, the electrode distance to the other electrode is different, the electrode distance of the light emitting element in one light emitting element group is the same as the electrode distance of the light emitting element in the other light emitting element group, and the other Another electrode pad formed in common with the electrode is provided.
[0067]
Thus, by arranging the electrode pad formed in common for the plurality of one electrode and further arranging the other electrode pad formed in common for the plurality of other electrodes, the number of electrode pads is reduced. The arrangement area is reduced, thereby achieving high density of the light emitting elements and miniaturization of the LED array.
[0068]
In addition, the number of processes is reduced compared with the LED array having a multilayer electrode structure as proposed in Japanese Patent Laid-Open Nos. 9-277592 and 11-40842, and a multilayer electrode structure having an interlayer insulating film is used. By not using the LED array, the manufacturing cost is reduced, and an LED array in which the density and size of the light emitting elements are achieved can be obtained. Further, in order to energize the other electrode of each light emitting element having the same electrode spacing, a connection line is formed in parallel with the array line of the light emitting elements so as to straddle the insulating film formed in the extending part of the one-conductivity type semiconductor layer. is doing. Therefore, in the conventional LED array, in addition to the insulating film formed as is well known, an interlayer insulating film that is indispensable for the electrical insulation between the wirings is not formed. This reduces the manufacturing cost and reduces the cost. LED arrays are provided. Furthermore, the symmetric electrode spacing pattern is obtained by changing the individual electrode spacing within the light emitting device group in the arrangement order with respect to one light emitting device group and the other light emitting device group. As a result, the signal processing of the light emission order when the LED head is mounted can be made relatively easy, and the design of the mounting board can also be facilitated. Then, by regularly arranging the regular pattern in the LED array, it becomes easy in design to provide electrode pads in other regions. It is possible to provide a large space in the shortest part of the symmetrical electrode interval. As a result, the size of the LED array chip can be reduced, and a larger wire bonding pad can be used for mounting the LED array. As a result, it is possible to reduce the chip size of the LED array and improve the yield in manufacturing the LED head. In the above LED array, a resin film is formed on the surface, and at the same time, at least the electrode connection part to the external circuit and the upper part of the reverse conductivity type semiconductor layer are covered. Therefore, the insulating film is formed according to the wavelength of the LED array. In addition, the resin film is designed to have the lowest optical transmittance with respect to the wavelength of the LED array, thereby reducing the stray light and improving the MTF. Realized. Further, in the case of an opaque film containing a dye, the resin film can be further improved, and an LED head with high MTF and high print quality can be provided.
[0069]
Next, a method for manufacturing the LED array as described above will be described.
[0070]
First, a one-conductivity-type semiconductor layer 2 and a reverse-conductivity-type semiconductor layer 3 are sequentially stacked on a high-resistance silicon single crystal substrate 1 by MOCVD or the like.
[0071]
First, when these semiconductor layers 2 and 3 are formed, the substrate temperature is set to 400 to 500 ° C., thereby forming an amorphous gallium arsenide film with a thickness of 200 to 2000 mm, and then the substrate temperature is set to 700 to The temperature is raised to 900 ° C. to form the one-conductivity-type semiconductor layer 2 and the reverse-conductivity-type semiconductor layer 3 having a desired thickness.
[0072]
In this film formation, as source gases, TMG ((CH ₃ ) ₃ Ga), TEG ((C ₂ H ₅ ) ₃ Ga), arsine (AsH ₃ ), TMA ((CH ₃ ) ₃ Al), TEA (( C ₂ H _{5) 3} Al) and the like are used as the gas for controlling conductivity types, silane (SiH _4), hydrogen selenide (H ₂ Se), and _{DMZ ((CH 3) 2 Zn} ) As the carrier gas, H ₂ or the like is used.
[0073]
Next, the semiconductor layers 2 and 3 are patterned in an island shape so that adjacent elements are electrically isolated. Etching for that purpose is performed by wet etching using a sulfuric acid hydrogen peroxide-based etching solution, dry etching using CCl ₂ F ₂ gas, or the like.
[0074]
Thereafter, an extension 7 is provided on one end side of the one conductivity type semiconductor layer 2, a part of the extension 7 is exposed on the extension 7, and an adjacent region portion of the one conductivity type semiconductor layer 2 is Etch to be exposed. In addition, the reverse conductivity type semiconductor layer 3 is etched so that the reverse conductivity type semiconductor layer 3 is formed narrower than the one conductivity type semiconductor layer 2.
[0075]
Such etching is also performed by wet etching using a sulfuric acid hydrogen peroxide-based etching solution or dry etching using CCl2 F2 gas.
[0076]
Next, etching is performed with, for example, an alkaline aqueous solution so that adjacent light emitting elements are electrically separated even on the substrate. At this time, a part of the extended portion 7 of the one-conductivity-type semiconductor layer 2 is exposed, and an adjacent region portion of the one-conductivity-type semiconductor layer 2 is exposed, and the reverse-conductivity-type semiconductor layer 3 is It is performed while leaving the pattern used when the reverse conductive semiconductor layer 3 is etched so as to be formed narrower than the conductive semiconductor layer 2, so that the reverse conductive semiconductor layer 3 can be electrically connected without any changes. To separate.
[0077]
Next, an insulating film 6 made of an organic resin by spin coating is formed. The insulating film may be made of silicon nitride using silane gas (SiH ₄ ) and ammonia gas (NH ₃ ) by plasma CVD.
[0078]
The electrode pads 9 and 10 and the connection line 11 are formed by forming and patterning chromium and gold by vapor deposition or sputtering. Finally, the protective film 12 formed with an organic resin by spin coating is formed.
[0079]
【The invention's effect】
As described above, according to the LED array of the present invention, at least a part of the light emitting region of the reverse conductivity type semiconductor layer is covered with the light-transmitting electrical insulating film, and further, other than the light emission region of the reverse conductivity type semiconductor layer. By covering the portion with a light-shielding synthetic resin layer, stray light was reduced or eliminated, thereby obtaining a high-quality and high-reliability LED array with improved MTF.
[0080]
In the LED array of the present invention, a one-conductivity-type semiconductor layer, a reverse-conductivity-type semiconductor layer, and one electrode are sequentially stacked on a single crystal substrate, and the one-conductivity-type semiconductor layer is drawn on the extended portion. A plurality of light emitting element groups, each having a plurality of light emitting elements formed by arranging the other electrode and the insulating film side by side, and an electrode pad formed in common for each of the electrodes of these light emitting elements are arranged. In the arrangement arranged in the form of individual lines, the electrode spacing to the other electrode in the extending part of each light emitting element in the light emitting element group is different, and the electrode spacing of the light emitting element in one light emitting element group and the other light emitting element group The electrode spacing of the light emitting element is made the same, and other electrode pads formed in common for both other electrodes are arranged, thereby reducing the number of electrode pads and reducing the arrangement area, As a result, the height of the light emitting element Cathodic, and downsizing of the LED array was achieved.
[0081]
Compared to conventional LED arrays with a multilayer electrode structure, the number of processes is reduced, and the multilayer electrode structure with an interlayer insulating film is not used, thereby reducing manufacturing costs and increasing the density and miniaturization of light-emitting elements. As a result, an LED array was achieved.
[0082]
In the above LED array, a resin film is formed on the surface, and at the same time, at least the electrode connection part to the external circuit and the upper part of the reverse conductivity type semiconductor layer are covered. Therefore, the insulating film is formed according to the wavelength of the LED array. In addition, the resin film is designed to have the lowest optical transmittance with respect to the wavelength of the LED array, thereby reducing the stray light and improving the MTF. Realized. Further, in the case of an opaque film containing a dye, the resin film can be further improved, and an LED head with high MTF and high print quality can be provided.
[Brief description of the drawings]
FIG. 1 is a plan view showing an embodiment of an LED array of the present invention.
FIG. 2 is a cross-sectional view taken along the line VV ′ shown in FIG.
FIG. 3 is a cross-sectional view taken along the line hh ′ shown in FIG.
FIG. 4 is a plan view showing an embodiment of the LED array of the present invention.
FIG. 5 is a plan view showing an embodiment of a conventional LED array.
FIG. 6 is a cross-sectional view showing a conventional LED array.
FIG. 7 is a plan view showing an embodiment of a conventional LED array.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Single crystal substrate 2 ... One conductivity type semiconductor layer 3 ... Reverse conductivity type semiconductor layer 4 ... Individual electrode 5 ... Common electrode 6 ... Insulating film 7 ... Extension part 8 ... Electrode pad 9 ... Light emitting element group 10 ... Electrode pad 11 ... Connection line x ... Electrode interval A ... Light emitting region

Claims (5)

At least one conductivity type semiconductor layer and the opposite conductivity type semiconductor layer and the electrode and sequentially stacked comprising light-emitting device is a plurality arranged on a substrate, there an LED array for emitting light from the light emitting region of the upper surface of the light emitting element And
The light emitting element has a slope including at least an end surface of a light emitting layer constituting the reverse conductivity type semiconductor layer and an end surface of at least a part of the one conductivity type semiconductor layer in a portion other than the light emitting region on the upper surface. ,
In the light emitting element, at least a region including the inclined surface is covered with a light-transmitting electrical insulating film,
A light-shielding synthetic resin layer is provided on a portion of the electrical insulating film that covers the inclined surface so as to cover the entire inclined surface including an end face of the light emitting layer .   2. The LED array according to claim 1, wherein the light-shielding synthetic resin layer comprises a synthetic resin material containing a dye.   The LED array according to claim 1, wherein the synthetic resin material is polyimide.   The electrical insulating film covers the slopes of the plurality of light emitting elements and the upper surface substantially parallel to the substrate surface of the reverse conductivity type semiconductor layer. LED array described in 1. The light emitting region is in a range of an upper surface substantially parallel to the substrate surface of the reverse conductivity type semiconductor layer,
The LED array according to any one of claims 1 to 4, wherein the light-shielding synthetic resin layer covers the electrical insulating film over the entire slope.

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