JPH10157193A - Light emitting diode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light emitting diode capable of preventing an electrode from being shorted and of reducing a device in size. SOLUTION: An island type first semiconductor layer 2 of one conductive type is provided in a line on a semiconductor substrate 1 and a second semiconductor layer 3 of a reverse conductive type is provided on the first semiconductor layer 2. Common electrodes 5a, 5b are connected to the first semiconductor layer 2 and an individual electrode 4 is connected to the second semiconductor layer 3. An insulation film 6 is provided on the semiconductor substrate. The individual electrode 4 is formed on the insulation film 6 and a recess section 9 is provided to a part of the semiconductor substrate. The common electrodes 5a, 5b are provided in the recess section 9 or on the insulation film 6. The individual electrode 4 is provided in the recess section 9.

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 line AA of FIG. FIG.
6, reference numeral 21 denotes a semiconductor substrate, 22 denotes a first semiconductor layer, 23 denotes a second semiconductor layer, 24 denotes an individual electrode,
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 reverse conductivity type semiconductor impurity.

[0006] Common electrodes 25 a and 25 b are provided near both side ends of the semiconductor substrate 1.
An 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 a wiring 27, and the common electrodes 25a, 25
b is connected to the first semiconductor layer 22 via the wirings 28a and 28b. The wirings 27, 28a, 28b are connected to the second semiconductor layer 23 and the first semiconductor layer 22, respectively, through through holes formed in the insulating film 26.

The common electrode 25 is divided into two groups so that adjacent first semiconductor layers 22 alternately belong to different groups, and the individual electrodes 24 are connected to the first semiconductor layers 22 belonging to different groups. Are connected to each other. The individual electrodes 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 and 23, the individual electrodes 24 and the common electrodes 25
The individual light emitting diodes are constituted by a and 25b, and each light emitting diode selectively emits light by selecting a combination of the individual electrode 24 and the common electrodes 25a and 25b and flowing an electric current.

[0008]

However, in this 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 are connected to the individual electrodes 24. Is connected to the second semiconductor layer 23 on the first semiconductor layer 22 belonging to a different group, but since the individual electrodes 24 are provided between the common electrodes 25a and 25b and the first semiconductor layer 22, Individual electrode 24
Are provided close to the common electrodes 25a and 25b and the wirings 28a and 28b, and there is a problem that short-circuiting due to misalignment of wire bonding and short-circuiting of electrodes due to poor etching at the time of electrode formation are liable to be caused.

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

The present invention has been made in view of such problems of the conventional device, and has as its object to provide a light emitting diode array in which short-circuiting of electrodes and enlargement of the device are prevented.

[0011]

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

Further, in the light emitting diode array according to the present invention, an island-shaped first semiconductor layer having one conductivity type is provided in a row on a semiconductor substrate, and an opposite conductivity type is provided on the first semiconductor layer. A second semiconductor layer is provided, and a common electrode is connected to the first semiconductor layer, and an individual electrode is connected to the second semiconductor layer. An insulating film was provided, the common electrode was formed on the insulating film, a recess was provided in a part of the semiconductor substrate, and the individual electrode was formed in the recess.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a view showing one embodiment of a light emitting diode array according to the present invention, and FIG.
FIG. 3 is a sectional view taken along line A. 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 made of, for example, silicon (Si).
And a single-crystal semiconductor substrate such as gallium arsenide (GaAs), 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}
As), which is composed of a two-layer film and contains one conductivity type impurities. This first semiconductor layer 2 is formed, for example, by MOCVD or M
It is formed by a BE method or the like. That is, the natural oxide film of the semiconductor substrate 1 is removed at a high temperature of 800 to 1000 ° C.
After growing amorphous gallium arsenide, which is a nucleus at a low temperature of 50 ° C. or less, to a thickness of about 0.1 to 2 μm by MOCVD or MBE, the temperature is raised to 450 to 700 ° C. to recrystallize the gallium arsenide single crystal. Is grown (two-stage growth method). In this case, trimethyl gallium ((CH ₃ ) ₃ Ga) or the like is used as a raw material of gallium, and arsine (AsH ₃ ) or the like is used as a raw material of arsenic. Next, annealing at a high temperature of 750 to 1000 ° C. and 600 ° C.
Repeat quenching to the following low temperature several times (temperature cycle method)
Post annealing such as is performed. When a two-layer structure of gallium arsenide and aluminum gallium arsenide is used, trimethyl aluminum ((CH ₃ )) is used as a raw material of aluminum.
₃ Al) is used.

On the first semiconductor layer 2, a second semiconductor layer 3 is formed. That is, the second semiconductor layer 3 is formed such 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 a reverse conductivity type impurity. 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 the opposite conductivity type impurity.
The first semiconductor layer 2 contains semiconductor impurities such as Zn and Cd in an amount of about 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
^Contains about ^-3 .

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

As described above, when the concave portion 9 is provided near the end of the semiconductor substrate 1 and the common electrodes 5a and 5b are provided in the concave portion 9, not only the width in the width direction but also the width of the electrode and the wiring in the thickness direction are reduced. Since the reference surfaces are different, short-circuiting of the electrodes can be effectively prevented.

Incidentally, the concave portion 9 is formed on substantially the entire surface of the semiconductor substrate 1.
A first semiconductor layer 2 and a second semiconductor
Forming body layer 3 and etching so that only element region remains
Etching may be performed at the same time. In this case, KO
H or NH_FourF: H_TwoO _TwoEtching solution such as
Can be.

FIGS. 3 and 4 show one embodiment of the light emitting diode array according to the second aspect of the present invention. This invention is also substantially the same as the invention described in the first aspect, but in this invention, a concave portion 10 is formed in the semiconductor substrate 1 below the individual electrode 4, and the individual electrode 4 is provided in the concave portion 10. The electrodes 5a and 5b were formed on the protective film 6 on the semiconductor substrate 1. In this manner, the individual electrodes 4 are
The common electrodes 5a and 5b and the individual electrodes 4 can be formed on different reference planes in the thickness direction.

[0021]

As described above, according to the first aspect of the present invention, the concave portion is provided on the semiconductor substrate, the common electrode is formed in the concave portion, and the individual electrode is formed on the semiconductor substrate. In addition, the heights of the reference surfaces of the common electrode and the individual electrodes can be made different, and the short circuit of the electrodes in the wire bonding step and the short circuit of the electrodes during the formation of the wiring can be greatly reduced. The same effect is obtained by face bonding such as flip chip bonding.

According to the second aspect of the present invention, a concave portion is provided on the semiconductor substrate, an individual electrode is formed in the concave portion, and a common electrode is formed on the semiconductor substrate. The height of the reference surface of the electrode can be made different, and the short circuit of the electrode in the wire bonding step and the short circuit of the electrode in forming the wiring can be greatly reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of a light emitting diode array according to claim 1.

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

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

FIG. 4 is a sectional view taken along line AA of FIG. 3;

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

FIG. 6 is a sectional view taken along line AA of FIG. 5;

[Explanation of symbols]

1 ... semiconductor substrate, 2 ... first semiconductor layer, 3 ...
The second semiconductor layer, 4... Individual electrodes, 5 (5a, 5
b) common electrode, 9, 10 recess

Claims (2)

[Claims] 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 the first semiconductor layer and an individual electrode is connected to the second semiconductor layer, an insulating film is provided on the semiconductor substrate, and the insulating film is provided on the insulating film. A light emitting diode array, wherein the individual electrodes are formed, a recess is provided in a part of the semiconductor substrate, and the common electrode is formed in the recess. 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 the first semiconductor layer and an individual electrode is connected to the second semiconductor layer, an insulating film is provided on the semiconductor substrate, and the insulating film is provided on the insulating film. A light emitting diode array, wherein the common electrode is formed, a recess is provided in a part of the semiconductor substrate, and the individual electrode is formed in the recess.