JPH06350132A - Semiconductor luminous element array - Google Patents

Abstract

PURPOSE:To provide a high quality semiconductor luminous element array having uniform luminous element characteristics at low cost by forming a high resistance portion in the upper part of a semiconductor crystal layer through ion implantation, thus electrically separating a luminous element, forming electrodes on a flat surface, and thereby integrating such luminous elements at a higher density. CONSTITUTION:A buffer layer 3 and a reflection layer 4 are formed on a substrate 2, and a cladding layer 5, a luminous layer 6, a cladding layer 7 and a contact layer 8 are formed on the reflection layer 4 in this order. Ion implantation is performed using a Au film 9 as a mask to separate a luminous element 11. Electrodes 13 are led out through the upper face of a SiN reflection preventive film 12 formed on the upper face of a semiconductor crystal layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor light emitting device array, and more particularly to a semiconductor light emitting device monolithic array having surface emitting semiconductor light emitting devices.

[0002]

2. Description of the Related Art Conventionally, a semiconductor light emitting element integrated in high density to form an array has been used as a light source for an optical printer or an information processing element using light. In recent years, due to the miniaturization of printers and the improvement in image quality, higher integration of light emitting elements is required. In a semiconductor light-emitting element monolithic array in which light-emitting elements are formed in rows by electrically separating semiconductor crystal layers sequentially stacked on a substrate, impurity diffusion methods and mesa-type etching methods are used as methods for separating light-emitting elements. Are used.

In a semiconductor light emitting device array using the impurity diffusion method, impurities are easily diffused at the interface between the diffusion mask and the semiconductor crystal layer in the light emitting portion, and the diffusion spreads to the light emitting portion, which lowers the light emission output or emits light. There is a drawback that the manufacturing yield is deteriorated due to variations among the elements. Therefore, a mesa-type etching method is widely used in which unevenness is formed on the substrate surface to separate each light emitting element.

Next, an example of a conventional semiconductor light emitting element array by the mesa type etching method will be described with reference to FIGS. 3 and 4. FIG. 3 is a partially enlarged sectional view in the column direction showing the structure of a conventional semiconductor light emitting device array, and FIG. 4 is a portion in the direction perpendicular to the column direction showing the structure of an example of a conventional semiconductor light emitting device array. It is an expanded sectional view. In both figures, the semiconductor light emitting element array 21 of the conventional example is an n-GaAs substrate 2
N-GaAs buffer layer 3 and n-Al _0.45 Ga
25 sets of reflective layers 4, n-Al _0.7 Ga _0.3 As clad layers 5, each including _0.55 As and n-AlAs as one set,
p-Al _0.3 Ga _0.7 As light emitting layer 6, p-Al _0.7 Ga
A semiconductor crystal layer in which _0.3 As clad layer 7 is sequentially laminated,
It has a plurality of light emitting elements 11 separated by a separation groove 15 by etching, and a SiN antireflection film 12 is formed on the upper surface of the semiconductor crystal except the electrode junction and the surface of the separation groove 15. An electrode 13 is provided on the entire lower surface of the substrate 2. In addition, an electrode 13 is provided on the upper surface of the clad layer 7 of each light emitting element 11 via a contact layer 8, and the electrode 13 is drawn out so as to crawl on the mesa type etching groove.

Here, each film of the reflection layer 4 is
The material is selected to maximize the reflectance by interference, and the light emitted from the light emitting layer 6 to the substrate 2 side is reflected by the reflective layer 4 to eliminate the light absorption by the substrate 2.
Usually, this film thickness d is given by the following equation when the refractive index of the member is n and the emission center wavelength is λp. d = λp / 4n Further, the performance (maximum reflectance) of the reflective layer 4 can be improved by increasing the number of sets.

The SiN antireflection film 12 removes the reflected component of the output light on the light output surface by interference and maximizes the transmittance, and is interposed between the electrode 13 and the semiconductor crystal layer. Let it also work as an insulator. The normal film thickness d is
When the refractive index of the member is n ₁ and the emission center wavelength is λp, the film thickness d is given by the following equation. d = λp / 4n ₁ Further, if a plurality of films having different refractive indices are laminated under the conditions of the film thickness d described above, the effect of antireflection can be further obtained.

[0007]

By the way, in the conventional semiconductor light emitting element array 21 having the above-described structure, when the isolation groove is formed by etching, the etching has a characteristic of advancing in all directions. The required depth greatly limits the distance between the light emitting devices. Moreover, the etching easily spreads to the light emitting portion, and the shape of the etching groove is likely to vary. Therefore, it has been difficult to produce a high-density and high-quality semiconductor light-emitting element array in which the distance between the light-emitting elements is extremely small and the characteristics of the light-emitting elements are uniform. Further, since the electrode 14 is pulled out so as to crawl on the mesa-shaped separation groove, when the electrode 14 is formed by vapor deposition or the like, the mesa-shaped shoulder portion becomes thin, and cracks easily occur due to the influence of stress. Because,
The thickness of the electrode 14 was uneven, and the electric resistance was varied. As a result, the light emission output varies. Further, there is a defect that defects such as disconnection are likely to occur and the manufacturing yield is deteriorated.

Therefore, the present invention has been made by paying attention to the above points, and in a semiconductor light emitting device array in which a semiconductor crystal layer is formed on a substrate and a plurality of light emitting devices are electrically isolated to form a plurality of light emitting devices. , By integrating light-emitting elements in higher density,
It is an object of the present invention to provide a high-quality semiconductor light emitting device array that makes the light emitting device characteristics uniform at low cost.

[0009]

In the semiconductor light emitting device array of the present invention, a semiconductor crystal layer in which semiconductor light emitting layers having different conductivity types are bonded and sandwiched so as to sandwich a light emitting layer on a substrate is electrically separated. In the semiconductor light emitting device array having a plurality of light emitting devices formed therein, ions are injected into the semiconductor crystal layer to electrically separate the light emitting devices, and an antireflection film is formed on the upper surface of the semiconductor crystal layer. The above-mentioned object is achieved by adopting a configuration in which each electrode on one side connected to a plurality of light emitting elements is drawn out through the upper surface of the antireflection film.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. The same components as those of the above-described conventional example or components corresponding to those of the conventional example are denoted by the same reference numerals, and the description thereof may be omitted. FIG. 1 is a partially enlarged plan view showing a structure of an embodiment of a semiconductor light emitting device array of the present invention, and FIG. 2 is a partially enlarged sectional view in a column direction showing a structure of an embodiment of a semiconductor light emitting device array of the present invention. It is a figure.

In both figures, the semiconductor light emitting device array 1 is shown.
First, n-GaA having a carrier concentration of 2 × 10 ¹⁸ cm ⁻³ and a film thickness of 0.5 μm was prepared by adding Se onto the n-GaAs substrate 2.
s buffer layer 3 is laminated, and then Se is added to make n-Al _0.45 having a carrier concentration of 2 × 10 ¹⁸ cm ⁻³ and a film thickness of 51 nm.
The reflective film 4 is formed by stacking 25 sets of Ga _0.55 As and n-AlAs having a film thickness of 59 nm as one set.

Further, Se is added on the reflective film 4 to make n-Al _0.7 having a carrier concentration of 1 × 10 ¹⁸ cm ^-3 and a film thickness of 5 μm.
Ga _0.3 As clad layer 5 and Zn-added p-Al _0.3 with a carrier concentration of 5 × 10 ¹⁷ cm ^-3 and a film thickness of 0.5 μm.
Ga _0.7 As light emitting layer 6 and Zn-added p-Al _0.7 Ga _0.3 with a carrier concentration of 8 × 10 ¹⁷ cm ^-3 and a film thickness of 2 μm.
As clad layer 7 and Zn are added so that the carrier concentration is 3 ×
A p-GaAs contact layer 8 having a thickness of 10 ¹⁸ cm ⁻³ and a thickness of 0.1 μm is laminated. These are all metal organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (M
BE method) or the like.

Subsequently, an Au film 9 is laminated on the semiconductor layer by vapor deposition or sputtering, and a photoresist film is applied. A desired pattern is formed on the photoresist film using a lithography technique. The part of the Au film which is not masked by the resist film is removed by the ion milling method or the sputtering method. Subsequently, using the remaining Au film 9 as an etching mask, proton irradiation is performed to form a high resistance portion 10 up to a depth of 3 μm from the surface on the portion outside the mask to separate the light emitting element 11. Lithography technology,
A part of the Au film is removed by using the sputtering method and used as an electrode. An etching solution composed of a mixed solution of ammonia and hydrogen peroxide water is used to leave a bonding portion with the Au film 9
After removing the p-GaAs contact layer 8, a SiN antireflection film 12 which is also an insulating film is formed to a film thickness of 97 nm on the entire upper surface of the p-Al _0.7 Ga _0.3 As clad layer 7 by a vapor phase growth method (CVD method). To do.

Next, an electrode 13 is formed on the upper surface of the antireflection film 12 by a lithographic technique and sputtering so as to be connected to the Au film 9 left on the light emitting element 11 and drawn out. To form.

In the semiconductor light emitting device array 1 of one embodiment of the present invention having the above-described structure, the high resistance portion 10 is formed on the semiconductor crystal layer by ion implantation to electrically separate the light emitting devices. The amount and depth of the ions can be accurately controlled, and the penetration depth can be easily controlled by controlling the energy applied to the ions. Does not spread to the part. Therefore, it is possible to reduce the distance between the light emitting elements without affecting the characteristics of the light emitting elements, and it is possible to divide the light emitting elements into more light emitting elements. That is, it is possible to provide a high-quality semiconductor light emitting element array in which light emitting elements are integrated in a very high density. Moreover, since the electrode 13 is formed on the flat SiN antireflection film 12, the thickness of the electrode 13 can be easily made uniform, and variations in the electric resistance of the electrode 13 can be reduced. As a result, the light emission output can be made uniform. Moreover, defects such as disconnection of the electrode 13 are reduced, and the manufacturing yield is improved.

The specific numerical values used in this embodiment and
The material names and the like are used only for the purpose of explanation, and the semiconductor light emitting element array according to the present invention is not limited to them, and can be appropriately changed in a situation where the semiconductor light emitting element array is used. Is.

[0017]

The semiconductor light emitting device array according to the present invention is
Since the light emitting elements are integrated with higher density and have high quality with excellent light emitting characteristics, it can be provided at low cost.

[Brief description of drawings]

FIG. 1 is a partially enlarged plan view showing the structure of an embodiment of a semiconductor light emitting device array of the present invention.

FIG. 2 is a partially enlarged sectional view in a column direction showing a structure of an embodiment of a semiconductor light emitting device array of the present invention.

FIG. 3 is a partially enlarged sectional view in a column direction showing a structure of an example of a conventional semiconductor light emitting element array.

FIG. 4 is a partial enlarged cross-sectional view in a direction perpendicular to a column direction, showing a structure of an example of a conventional semiconductor light emitting device array.

[Explanation of symbols]

 1 Semiconductor Light Emitting Element Array 2 Substrate 4 Reflective Layer 5 Clad Layer (Semiconductor Crystal Layer) 6 Light Emitting Layer 7 Clad Layer (Semiconductor Crystal Layer) 8 Contact Layer 9 Au Film 10 High Resistance Part 11 Light Emitting Element 12 Antireflection Film 13 Electrode

Claims (1)

[Claims] 1. A semiconductor light-emitting element array in which a plurality of light-emitting elements are formed by electrically separating a semiconductor crystal layer, which is formed by bonding and laminating a light-emitting layer between semiconductor crystal layers having different conductivity types, on a substrate. In, in order to electrically separate the light emitting element by implanting ions into the semiconductor crystal layer, an antireflection film that maximizes the transmittance of the emission wavelength is formed on the upper surface of the semiconductor crystal layer, A semiconductor light emitting device array, wherein each electrode on one side connected to the light emitting device is drawn out through the upper surface of the antireflection film.