JP3420449B2 - Light emitting diode array - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting diode array, and more particularly to a light emitting diode array used as an exposure source of a photosensitive drum for a page printer.

[0002]

2. Description of the Related Art A conventional light emitting diode array is shown in FIGS. FIG. 6 is a sectional view taken along the line AA of FIG. Figure 5
6, 21 is a semiconductor substrate, 22 is a first semiconductor layer, 23 is a second semiconductor layer, 24 is an individual electrode, 25
Is a common electrode.

The semiconductor substrate 21 is made of, for example, silicon (S
i) or a single crystal semiconductor substrate such as gallium arsenide (GaAs). The first semiconductor layer 22 is made of a compound semiconductor layer such as gallium arsenide or aluminum gallium arsenide, and contains one conductivity type semiconductor impurity. The second semiconductor layer 23 is also made of a compound semiconductor layer such as gallium arsenide or aluminum gallium arsenide and contains a semiconductor impurity of the opposite conductivity type.

Common electrodes 25a and 25b are provided near both ends of the semiconductor substrate 1, and the common electrodes 25a and 25b are provided.
The individual electrode 24 is provided between b and the island-shaped semiconductor layers 22 and 23. In FIG. 6, reference numeral 26 denotes an insulating protective film made of a silicon nitride film or the like provided on the semiconductor substrate 21, the first semiconductor layer 22 and the second semiconductor layer 23.

The individual electrode 24 is connected to the second semiconductor layer 23 via the wiring 27, and the common electrodes 25a, 25 are also provided.
b is connected to the first semiconductor layer 22 via the wirings 28a and 28b. The wirings 27, 28a, 28b are respectively connected to the second semiconductor layer 23 and the first semiconductor layer 22 via through holes formed in the insulating film 26.

Adjacent first semiconductor layers 22 are connected to the common electrode 25 by being divided into two groups so as to be alternately belonging to different groups, and the individual electrodes 24 are formed on the first semiconductor layers 22 belonging to different groups. The two adjacent second semiconductor layers 23 are connected. The individual electrode 24 and the common electrodes 25a and 25b are connected to an external circuit by a wire bonding method or the like.

In such a light emitting diode array, the semiconductor layers 22, 23, the individual electrode 24 and the common electrode 25 are included.
A light emitting diode is configured by a and 25b, and by selecting a combination of the individual electrode 24 and the common electrodes 25a and 25b and passing an electric current, each light emitting diode selectively emits light.

[0008]

However, in the conventional light emitting diode array, the common electrode 25 is divided into two groups so that the adjacent first semiconductor layers 22 belong to different groups, and the individual electrodes 24 are connected to each other. Although the second semiconductor layer 23 on the first semiconductor layer 22 belonging to a different group is connected to, the individual electrode 24 is provided between the common electrodes 25a and 25b and the first semiconductor layer 22, Individual electrode 24
Is provided close to the common electrodes 25a and 25b and the wirings 28a and 28b, and there is a problem that short circuits due to misalignment of wire bonding and electrode short circuits due to etching defects during electrode formation are likely to occur.

Therefore, from the individual electrode 24 to the common electrode 25
Since the a and 25b and the wirings 28a and 28b must be provided separately from each other, there is a problem that the size of the entire device increases.
In particular, in order to prevent a short circuit due to the positional displacement of wire bonding, these electrode portions must be separated by 20 μm or more.

The present invention has been invented in view of the above problems of the conventional device, and an object thereof is to provide a light emitting diode array in which a short circuit of electrodes and an increase in size of the device are prevented.

[0011]

In order to achieve the above object, in a light emitting diode array according to a first aspect, island-shaped first semiconductor layers exhibiting one conductivity type are provided in rows on a semiconductor substrate, A second semiconductor layer having an opposite conductivity type is provided on the first semiconductor layer, a common electrode is connected to the first semiconductor layer, and an individual electrode is connected to the second semiconductor layer. In the provided light emitting diode array, an insulating film is provided on the semiconductor substrate, a recess is provided in a part of the semiconductor substrate, a common electrode is formed in the recess, and the recess and the first island-shaped semiconductor layer are formed. The individual electrodes were formed on the insulating film in between.

In the light emitting diode array according to the second aspect, island-shaped first semiconductor layers exhibiting one conductivity type are provided in a row on the semiconductor substrate, and the opposite conductivity type is provided on the first semiconductor layer. In a light-emitting diode array provided with a second semiconductor layer to be provided, a common electrode is connected to the first semiconductor layer, and an individual electrode is connected to the second semiconductor layer, on the semiconductor substrate. An insulating film is provided, the common electrode is formed on the insulating film, and a recess is provided in a part of the semiconductor substrate between the common electrode and the first semiconductor layer, and the individual electrode is provided in the recess. Was formed.

[0013]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a view showing an embodiment of a light emitting diode array according to the present invention, and FIG. 2 is A- in FIG.
It is an A line sectional view. 1 and 2, 1 is a semiconductor substrate, 2 is a first semiconductor layer, 3 is a second semiconductor layer, 4 is an individual electrode, and 5 (5a, 5b) is a common electrode.

The semiconductor substrate 1 is, for example, silicon (Si).
And a gallium arsenide (GaAs) single crystal semiconductor substrate, and a high resistance substrate having a resistivity ρ of about 1000 to 2000 Ω · cm.

The first semiconductor layer 2 is made of gallium arsenide or gallium arsenide and aluminum gallium arsenide (Al _x Ga _{1 -x).}
It is composed of a double-layered film of As) and contains one conductivity type impurity. The first semiconductor layer 2 is formed by, for example, MOCVD method or M
It is formed by the BE method or the like. That is, the natural oxide film on the semiconductor substrate 1 is removed at a high temperature of 800 to 1000 ° C., and then 4
Amorphous gallium arsenide, which serves as a nucleus at a low temperature of 50 ° C. or lower, is grown to a thickness of about 0.1 to 2 μm by MOCVD or MBE, and then heated to 450 to 700 ° C. to be recrystallized to form a gallium arsenide single crystal. Grow (two-step growth method). In this case, trimethylgallium ((CH ₃ ) ₃ Ga) or the like is used as the raw material of gallium, and arsine (AsH ₃ ) or the like is used as the raw material of arsenic. Next, annealing at a high temperature of 750 to 1000 ° C. and 600 ° C.
Repeat rapid cooling to the following low temperature several times (temperature cycle method)
And post anneal. When a double-layered structure of gallium arsenide and aluminum gallium arsenide is used, trimethyl aluminum ((CH ₃ )) is used as a raw material of aluminum.
₃ Al) or the like is used.

A second semiconductor layer 3 is formed on the first semiconductor layer 2. That is, the second semiconductor layer 3 is formed so that a part of the first semiconductor layer 2 is exposed. The second semiconductor layer 3 is also made of a compound semiconductor film such as aluminum gallium arsenide and contains impurities of opposite conductivity type. The second semiconductor layer 3 may be formed of a plurality of layers having different mixed crystal ratios of aluminum arsenide (AlAs) and gallium arsenide (GaAs). A semiconductor junction is formed at the interface between the first semiconductor layer 2 containing one conductivity type impurity and the second semiconductor layer 3 containing opposite conductivity type impurity.
The first semiconductor layer 2 contains semiconductor impurities such as Zn and Cd in the order of 1 × 10 ¹⁸ to 1 × 10 ¹⁹ atoms cm ⁻³ , and the second semiconductor layer 3 contains S, Se, Te, Ge, 1 × 10 ¹⁶ to 1 × 10 ¹⁹ atoms of semiconductor impurities such as Si cm
^-Contain about ³

Recesses 9 are formed at both ends of the semiconductor substrate 1, and common electrodes 5a and 5b are formed in the recesses 9. The recess 9 is formed to a depth of about the thickness of the common electrodes 5a and 5b. The common electrodes 5a and 5b are the wiring 8
It is connected to the first island-shaped semiconductor layer 2 via a and 8b. The common electrodes 5a and 5b are alternately distributed and connected to each adjacent first island-shaped semiconductor layer 2. The individual electrode 4 is provided between the recess 9 and the second semiconductor layer 3. The individual electrode 4 is formed on the protective film 6 of the semiconductor substrate 1. Such individual electrodes 4, common electrodes 5a, 5
b and the wirings 7, 8a, 8b are formed of, for example, Au—Cr or the like, and have a thickness of 1 μm by a vacuum deposition method or a sputtering method.
It is formed to about m.

As described above, when the recess 9 is provided near the end of the semiconductor substrate 1 and the common electrodes 5a and 5b are provided in the recess 9, not only the adjacent electrodes and wirings but also the space in the width direction as well as the thickness direction. Since the reference planes of are also different, it is possible to effectively prevent a short circuit of the electrodes.

It should be noted that the above-mentioned recess 9 is formed on almost the entire semiconductor substrate 1.
The first semiconductor layer 2 and the second semiconductor are formed on the surface or a predetermined area.
Etching so that the body layer 3 is formed and only the element region remains
Etching may be performed at the same time. In this case, KO
H or NH_FourF: H₂O ₂Etching solution such as
Can be

3 and 4 are views showing an embodiment of a light emitting diode array according to the invention described in claim 2. This invention is also almost the same as the invention described in claim 1, but in this invention, the recess 10 is formed in the semiconductor substrate 1 below the individual electrode 4, and the individual electrode 4 is provided in this recess 10 The electrodes 5a and 5b were formed on the protective film 6 on the semiconductor substrate 1. In this way, the individual electrode 4 is formed in the recess 10
Even if formed inside, the common electrodes 5a and 5b and the individual electrode 4 can be formed on different reference planes in the thickness direction.

As described above, according to the first aspect of the invention, the insulating film is provided on the semiconductor substrate, the recess is provided in a part of the semiconductor substrate, and the common electrode is formed in the recess.
Since the individual electrodes are formed on the insulating film between the recess and the first island-shaped semiconductor layer, the heights of the reference planes of the common electrode and the individual electrodes can be made different, and the short circuit of the electrodes in the wire bonding process or It is possible to significantly reduce the short circuit of the electrodes when forming the wiring. Also, face bonding such as flip chip has the same effect.

According to a second aspect of the present invention, an insulating film is provided on the semiconductor substrate, the common electrode is formed on the insulating film, and a space between the common electrode and the first semiconductor layer is formed. Since the recess is provided in a part of the semiconductor substrate and the individual electrode is formed in the recess, the heights of the reference planes of the individual electrode and the common electrode can be made different, and the electrode short circuit in the wire bonding process can be achieved. It is possible to greatly reduce the short circuit of electrodes when forming wiring.

[Brief description of drawings]

FIG. 1 is a view showing an embodiment of a light emitting diode array according to claim 1.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a diagram showing an embodiment of a light emitting diode array according to claim 2;

4 is a cross-sectional view taken along the line AA of FIG.

FIG. 5 is a view showing a conventional light emitting diode array.

6 is a cross-sectional view taken along the line AA of FIG.

[Explanation of symbols]

1 ... Semiconductor substrate, 2 ... First semiconductor layer, 3 ...
-Second semiconductor layer, 4 ... Individual electrodes, 5 (5a, 5
b) ... Common electrode, 9, 10 ... Recessed portion

Claims (2)

(57) [Claims] 1. An island-shaped first semiconductor layer having one conductivity type is provided in a row on a semiconductor substrate, and a second semiconductor layer having an opposite conductivity type is provided on the first semiconductor layer. In a light emitting diode array in which a common electrode is connected to a first semiconductor layer and an individual electrode is connected to the second semiconductor layer, an insulating film is provided on the semiconductor substrate, And a common electrode is formed in the recess, and the recess and the first island-shaped semiconductor layer are formed.
A light emitting diode array , wherein the individual electrode is formed on the insulating film between and . 2. An island-shaped first semiconductor layer having one conductivity type is provided in a row on a semiconductor substrate, and a second semiconductor layer having an opposite conductivity type is provided on the first semiconductor layer. In a light-emitting diode array in which a common electrode is connected to a first semiconductor layer and an individual electrode is connected to the second semiconductor layer, an insulating film is provided on the semiconductor substrate, and an insulating film is provided on the insulating film. together to form the common electrode, the common collector
A light-emitting diode array, wherein a recess is provided in a part of the semiconductor substrate between a pole and the first semiconductor layer, and the individual electrode is formed in the recess.