JPH05335620A - Semiconductor light-emitting device and its manufacture - Google Patents

Abstract

PURPOSE:To reduce the fluctuation of light emitting outputs from each light emitting section. CONSTITUTION:An epitaxial layer 12 is provided on an n-type compound semiconductor substrate 11 and, in the layer 12, the central p-n junction surface of each light emitting section is projected in the direction opposite to the light- emitting surface and a p-type diffusion area 13 which is nearly parallel to the surface of the substrate 11 is provided at the p-n junction surface around the central p-n junction surface, with each area 13 being separated from another by means of a groove 14. The surface of the layer 12 is coated with a surface protective film 15 and the film 15 gets into the grooves 14. In addition, p-type electrodes 16 are vapor deposited on the light emitting surfaces of the areas 13 and an n-type electrode 17 is vapor-deposited on the rear surface of the substrate 11.

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 such as a monolithic light emitting diode array and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a light emitting diode array has been used in various devices such as a display device and an LED printer device as a light source.
Then, in a monolithic light-emitting diode array in which a plurality of light-emitting portions (light-emitting diode portions) are formed in rows on the surface of a compound semiconductor made of each layer epitaxially grown on a single crystal substrate, each light-emitting portion has a selective diffusion method or mesa. They are separated by a mold etching method or the like.
Then, for example, when the light emitting portion of the compound semiconductor in which the GaAsP layer is epitaxially grown on the GaAs substrate is separated by the selective diffusion method, Zn (zinc) is diffused to the boundary portion of each light emitting portion of the epitaxially grown GaAsP layer. However, it is often adopted as a suitable method for manufacturing a planar element.

A method of manufacturing a light emitting diode array using this selective diffusion method will be described with reference to the process charts shown in FIGS. First, as shown in FIG.
An n-type GaAsP layer 2 is epitaxially grown on the aAs substrate 1 by a vapor phase growth method or the like. And this GaA
On the sP layer 2, a selective diffusion mask 3 made of SiN or the like having windows 3a provided at respective positions serving as a light emitting portion is provided, and when the diffusion process is performed at a high temperature of several hundreds of degrees or more in a subsequent process, the GaAsP layer 2 is changed to As or As. In order to prevent the evaporation of P and the roughening of the substrate surface, a through diffusion film 4 such as SiO ₂ is provided on the selective diffusion mask 3. After that, when Zn is diffused by a diffusion method called, for example, a sealed tube method, the Zn penetrates through the through diffusion film 4 and GaA under the window 3a of the selective diffusion mask 3 is exposed.
A p-type diffusion region 5 is formed in the sP layer 2. Finally, as shown in FIG. 6B, after removing the through diffusion film 4, p-type electrodes 6 are provided on the respective p-type diffusion regions 5, and n-type G
A light emitting diode array can be manufactured by depositing the n-type electrode 7 on the back surface of the aAs substrate 1.

[0004]

Ideally, it would be ideal if a light emitting diode array having a diffusion region 5 as shown in FIG. 5B could be manufactured by the above-mentioned conventional selective diffusion method. Since the compatibility with the surface of the GaAsP layer 2 is poor, Zn diffuses quickly into the interface 8, and
The connected p-type diffusion region 9 is likely to be formed as in (C).
Further, in the p-type diffusion region 9 having such a shape, since the respective light emitting portions are electrically connected, there is a disadvantage that individual light emission cannot be performed. So Z
After the n-diffusion, the connection portion 10 of the p-type diffusion region 9 is separated, but even if the connection portion 10 is removed by etching, the diffusion amount of Zn to the interface 8 is different depending on the location. However, the shapes of the p-type diffusion regions 9 after etching are not uniform, and the amount of emitted light varies among the light emitting portions.

Further, Japanese Patent Laid-Open No. 195886/1984 discloses a method of diffusing and separating n-type impurities 10a such as S (sulfur) and Te (tellurium) in the connection portion 10. Not only is the manufacturing process complicated,
Since the temperature at which the n-type impurity 10a is diffused is higher than the diffusion temperature of Zn by about 200 to 300 ° C., the Zn diffused earlier is further diffused, and the impurity concentration distribution (profile) of the p-type diffusion region 9 is obtained. It becomes difficult to control. Furthermore, Z
Since the temperature is higher than the diffusion temperature of n, the surface roughness of the substrate could not be prevented even if the through diffusion film 4 was used. Therefore, it is an object of the present invention to solve the above problems and provide a semiconductor light emitting device in which variations in light emission output in each light emitting portion are small, and a manufacturing method thereof.

[0006]

As means for achieving the above object, in a semiconductor light emitting device having a plurality of light emitting portions formed in a row in a compound semiconductor having a pn junction, a central portion of each light emitting portion is provided. Is a convex surface in the direction opposite to the light extraction surface, the pn junction surface in the peripheral portion of the convex shape is substantially parallel to the substrate surface, and each light emitting portion is A semiconductor light emitting device characterized by being separated by a groove deeper than the pn junction surface of a peripheral portion, and a semiconductor light emitting device having a plurality of light emitting portions formed in rows on a surface of a compound semiconductor having a pn junction. A method of manufacturing, comprising a step of crystal-growing a second compound semiconductor layer on a first compound semiconductor substrate, and selectively etching the second compound semiconductor layer to form the plurality of light emitting portions. A window portion is formed on the first compound semiconductor substrate, and an impurity having a conductivity different from that of the first compound semiconductor substrate is diffused so as to be shallower than the thickness of the layer of the second compound semiconductor so that the pn junction surface has the second layer. A step of forming a diffusion region so as to extend from a compound semiconductor layer to the first compound semiconductor substrate, and a step of separating the diffusion region by removing the second compound semiconductor layer. A method for manufacturing a semiconductor light emitting device, or a method for manufacturing a semiconductor light emitting device in which a plurality of light emitting portions are formed in rows on a surface of a compound semiconductor having a pn junction, the surface of the compound semiconductor having a pn junction 1. A method of manufacturing a semiconductor light emitting device, comprising: forming a plurality of light emitting portions in a row on a substrate, comprising a step of crystal-growing a second compound semiconductor layer on a first compound semiconductor substrate; Selectively etching the compound semiconductor layer to form windows at positions that will become the plurality of light emitting portions, and impurities having a conductivity different from that of the first compound semiconductor substrate to all the pn junction surfaces. The first compound semiconductor substrate is diffused deeper than the thickness of the second compound semiconductor layer so that the pn junction surface under the window is convex in the direction opposite to the first compound semiconductor substrate surface. A step of forming a diffusion region having a mold shape, a step of removing the layer of the second compound semiconductor, and an etching between the convex-shaped portions of each of the diffusion regions are performed so as to be closer to the pn junction surface. And a step of separating the diffusion region by forming a deep groove, to provide a method for manufacturing a semiconductor light emitting device.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As a first embodiment of the semiconductor light emitting device of the present invention, a light emitting diode array is shown in FIG. 1 and will be described below.
In the light emitting diode array shown in the figure, an epitaxial layer 12 is provided on an n-type compound semiconductor substrate 11, and a p-type diffusion region 13 as shown in the figure is provided in the epitaxial layer 12.
Are provided, and the surface of the epitaxial layer 12 is covered with a surface protective film 15. A p-type electrode 16 is vapor-deposited on the light-extracting surface of the p-type diffusion region 13, and an n-type electrode 17 is vapor-deposited on the back surface of the n-type compound semiconductor substrate 11. Each p-type diffusion region 13 of this light emitting diode array is completely separated, and its shape is also constant.

A method of manufacturing such a light emitting diode array will be described with reference to FIGS. First, as shown in FIG. 1A, an epitaxial layer 12 made of a compound semiconductor such as GaAsP is grown on an n-type compound semiconductor substrate 11 such as GaAs by MOCVD (metal organic chemical vapor deposition). M on this epitaxial layer 12
Epitaxial layer 1 such as AlGaAs by OCVD method
A crystal growth layer (second compound semiconductor layer) 18 made of a compound semiconductor different from 2 is formed, and a SiN protective film 19 is further formed thereon by a plasma CVD method.
Then, a window portion 19a as shown in FIGS. 9B and 9C is opened by using a lithography process and dry etching with CF ₄ at the place where the light emitting portion of the protective film 19 is formed. The crystal growth layer 18 in the lower portion is removed by selective etching using hydrochloric acid. In addition,
In FIG. 3D, the etching surface of the crystal growth layer 18 is an inverted mesa type, but the effect does not change even if it is etched into a normal mesa type.

After that, the remaining protective film 19 is removed by dry etching with CF _{4, and then} a through diffusion film 20 of SiO 2 is applied to the entire surface of the substrate by a coating method as shown in FIG. Then, when a p-type impurity such as Zn is diffused into the crystal growth layer 18 at a temperature of 700 ° C. by the sealed tube method, Zn is diffused over the entire surface. Therefore, as shown in FIG. The p-type diffusion region 13 is formed in the epitaxial layer 12 only when the surface of the epitaxial layer 12 is exposed by etching the crystal growth layer 18. At this time, pn which is a boundary surface between the p-type diffusion region 13 and the n-type compound semiconductor is formed. The bonding surface 13a extends from the crystal growth layer 18 to the epitaxial layer 12. At this time,
Since the epitaxial layer 12 and the crystal growth layer 18 are both compound semiconductors, they have good matching at the interface, and the p-type impurities are diffused into this interface to cause the p-type diffusion region 13 to have an irregular shape. The bonding surface 13a is the epitaxial layer 12
There is no connection within itself.

Further, when the crystal growth layer 18 and the through diffusion film 20 are removed by etching, the respective diffusion regions 13 are finely separated as shown in FIG. And Si
After attaching the N surface protective film 15, Al is vapor-deposited to p
After forming the mold electrode 16 and polishing and thinning the back surface of the n-type compound semiconductor substrate 11, the n-type electrode 17 of AuGeNi alloy is vapor-deposited to obtain the light emitting diode array shown in FIG. In the semiconductor light emitting device manufactured in this manner, the diffusion regions of the respective light emitting portions are completely separated and the shape thereof is also constant, so that the current-light output characteristics between the respective light emitting portions are almost different. Not stick.

As a second embodiment of the semiconductor light emitting device of the present invention, a light emitting diode array having a structure different from that of the first embodiment is shown in FIG. 2 and described below. The light emitting diode array shown in the figure has an epitaxial layer 12 provided on an n-type compound semiconductor substrate 11.
As shown in the figure, the pn junction surface at the center of each light emitting portion has a convex shape in the direction opposite to the light extraction surface, and the p
The n-junction surface is provided with p-type diffusion regions 13 that are substantially parallel to the substrate surface, and each p-type diffusion region 13 is separated by a groove 14 deeper than the parallel pn-junction surface. The surface of the epitaxial layer 12 is covered with the surface protective film 15, and the surface protective film 15 is formed in the groove 1.
It is also getting into 4. A p-type electrode 16 is vapor-deposited on the light-extracting surface of the p-type diffusion region 13, and an n-type electrode 17 is vapor-deposited on the back surface of the n-type compound semiconductor substrate 11.

A method of manufacturing such a light emitting diode array will be described with reference to FIGS. 3A to 3D and FIGS. 4A and 4B. First, the same method as in the first embodiment described above is performed until the step of coating the through diffusion film 20 of SiO2 shown in FIG. Next, by the sealed tube method, 70
When a p-type impurity such as Zn is diffused to a depth deeper than the thickness of the crystal growth layer 18 at a temperature of 0 ° C., Zn is diffused over the entire surface, so that as shown in FIG.
8 is etched to expose the surface of the epitaxial layer 12 so that it is deeply diffused into a convex shape, and where the crystal growth layer 18 is present, it is diffused to a shallow position in the epitaxial layer 12 to form a surface with the epitaxial layer 12. The p-type diffusion region 1 diffuses substantially in parallel and has a convex shape in the direction opposite to the surface of the epitaxial layer 12 as shown in FIG.
3 is formed. At this time, the pn junction surface 13 a, which is the boundary surface between the p-type diffusion region 13 and the n-type compound semiconductor, is entirely present in the epitaxial layer 12. Also at this time, since the epitaxial layer 12 and the crystal growth layer 18 are both compound semiconductors, the matching at the interface is good, and the p-type impurity diffuses into this interface to make the p-type diffusion region 13 irregular. It never takes shape.

Further, after removing the crystal growth layer 18 and the through diffusion film 20 by etching, the plasma CV is again used.
By adding SiN by the D method, a window for separating each light emitting portion is formed in this SiN at a position between the light emitting portions, that is, a portion where the p-type impurity is shallowly diffused, and this SN is formed.
Using iN as an etching mask, the diffusion region 1 in this portion
Wet etching with phosphoric acid / hydrogen peroxide is performed to a position deeper than 3 to form a groove 14 as shown in FIG. 4 (B) to separate each light emitting portion and then remove SiN. afterwards,
After attaching the surface protective film 15 of SiN, Al is vapor-deposited to form the p-type electrode 16, and the n-type compound semiconductor substrate 11 is formed.
After polishing and thinning the back surface of n, the n-type electrode 17 of AuGeNi alloy is vapor-deposited to obtain the light emitting diode array shown in FIG.

In the semiconductor light emitting device manufactured as described above, the diffusion regions of the respective light emitting portions are completely separated by the groove 14, and the shape thereof is also constant, so that the current flowing between the respective light emitting portions is − Almost no variation in light output characteristics.
Then, even if the diffusion region is enlarged, the separation can be surely performed. Further, in each of the above-described embodiments, the diffusion region of each light emitting portion can be completely separated, so that each light emitting portion can independently emit light even if the light emitting portion is made small, and a light emitting dot of 2000 dpi or more is emitted. Can be manufactured satisfactorily.

[0015]

According to the semiconductor light emitting device of the present invention, the diffusion regions of the respective light emitting portions are separated by the grooves, and the respective diffusion regions also have a constant shape. Therefore, the variation of the current-light output characteristics in the respective light emitting portions. And good output can be obtained. Further, in the method for manufacturing the semiconductor light emitting device of the present invention, since the impurity diffusion is performed using the compound semiconductor as a mask, a diffusion region having a constant shape can be obtained, and even if the light emitting portion is made small, good and stable separation can be achieved. Therefore, it is possible to almost eliminate the variation in the current-light output characteristics in each light emitting portion. Furthermore, when the diffusion regions are separated by the grooves, there is an effect that the diffusion regions can be separated more reliably.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of a semiconductor light emitting device of the present invention.

FIG. 2 is a sectional view showing a second embodiment of the semiconductor light emitting device of the present invention.

3A to 3F are process diagrams showing a manufacturing method according to the first embodiment of the present invention.

4A and 4B are process diagrams showing a manufacturing method according to a second embodiment of the present invention.

5A to 5C are process diagrams showing a conventional manufacturing method.

[Explanation of symbols]

 1 n-type GaAs substrate 2 GaAsP layer 3 selective diffusion mask 3a window part 4,20 through diffusion film 5,9,13 p-type diffusion region 6,16 p-type electrode 7,17 n-type electrode 8 interface 10 connection part 10a n-type Impurity 11 n-type compound semiconductor substrate 12 epitaxial layer 14 groove 15 surface protective film 18 crystal growth layer (second compound semiconductor layer) 19 protective film

Claims (3)

[Claims] 1. A semiconductor light emitting device having a plurality of light emitting portions formed in a row in a compound semiconductor having a pn junction, wherein the pn junction surface at the center of each light emitting portion is convex in the direction opposite to the light extraction surface. This is a mold-shaped surface, the pn junction surface of the peripheral portion of the convex shape is a surface substantially parallel to the substrate surface, and each light emitting portion is separated by a groove deeper than the pn junction surface of the peripheral portion. A semiconductor light-emitting device characterized in that. 2. A method of manufacturing a semiconductor light-emitting device, comprising forming a plurality of light-emitting portions in rows on a surface of a compound semiconductor having a pn junction, the method comprising: forming a second compound semiconductor layer on a first compound semiconductor substrate. A step of growing a crystal, a step of selectively etching the second compound semiconductor layer to form a window portion at a position which becomes the plurality of light emitting portions, and an impurity having a conductivity different from that of the first compound semiconductor substrate. To form a diffusion region so that the pn junction surface extends from the second compound semiconductor layer to the first compound semiconductor substrate such that the diffusion region is diffused shallower than the thickness of the second compound semiconductor layer. And a step of separating the diffusion region by removing the second compound semiconductor layer. 3. A method for manufacturing a semiconductor light-emitting device, comprising forming a plurality of light emitting portions in rows on a surface of a compound semiconductor having a pn junction, wherein a plurality of light emitting portions are arranged in rows on a surface of a compound semiconductor having a pn junction. A method of manufacturing a semiconductor light-emitting device, the method comprising: crystallizing a second compound semiconductor layer on a first compound semiconductor substrate; and selectively etching the second compound semiconductor layer to form the plurality of layers. Forming a window portion at a position which becomes a light emitting portion of the second compound semiconductor substrate, and forming the window so that all pn junction surfaces reach the first compound semiconductor substrate with impurities having conductivity different from that of the first compound semiconductor substrate. Diffusing deeper than the thickness of the compound semiconductor layer to form a diffusion region in which the pn junction surface under the window has a convex shape in a direction opposite to the surface of the first compound semiconductor substrate, The above 2. The step of removing the compound semiconductor layer and the step of etching between the convex-shaped portions of the diffusion regions to form trenches deeper than the pn junction surface, thereby separating the diffusion regions. The manufacturing method of the semiconductor light-emitting device characterized by including the process.