JP2003110134A - Semiconductor light emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compound semiconductor light emitting element having high reliability and high light emitting efficiency. SOLUTION: A step coverage is improved by rounding the peripheral edge of the top surface of the light emitting element to prevent a protective film from being etched and the surface of the element from being exposed.

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] [0001] The present invention relates to a compound semiconductor material.
Light emitting diode (hereinafter, referred to as LED), especially
Made of a compound semiconductor containing aluminum (Al)
It relates to an LED. [0002] 2. Description of the Related Art LEDs are small, highly reliable, and display systems.
Distance measurement system, optical communication transmission system, etc.
Widely used for various purposes. [0003] This LED has an epitaxial growth surface.
A surface-emitting LED formed as a main light-emitting surface;
As with lasers, etc., the cleaved end face is used as the main light-emitting face.
They are roughly classified into emission type LEDs. [0004] Surface-emitting type LEDs have high brightness and high output for display.
Widely used as LEDs, and recently
Use outdoors, such as a stop stop lamp or outdoor display panel.
The applications used are also increasing. [0005] In this application, the emission wavelength is from 600 nm to 7 nm.
The orange to red wavelength of 00 nm is mainly used.
GaAlAs, InGaAl
Mixed crystal compound semiconductors containing Al such as P are used. [0006] Currently high-mount stop lamps and outdoor tables
The high-brightness red LED used for the display panel is Ga
The LED is made of AlAs, and the orange LED is In
LEDs made of GaAlP are the mainstream. Also,
LED using other materials also has a window layer on the element surface
Mixed crystal compound semiconductor containing Al is used for
There is something. FIG. 4 shows a conventional orange InGaAlPLED.
Show. [0008] The LED shown in FIG.
-Type GaAs buffer layer 2, n-type Al _0.35Ga_0.15In
_0.5P clad layer 3, Al_0.1Ga_0.4In_0.5P active layer
4, p-type Al_0.35Ga_0.15In_0.5P clad layer 5, A
l Zn-doped p-type Al with x = 0.7_0.7Ga_0.3
This is a double hetero structure in which As window layers 6 are sequentially formed. Further, a p-side electrode 7 is provided on the top side, and an n-side electrode is provided on the back side.
There is an electrode 8, and the element is divided by a mesa structure,
Mesa part is SiO_TwoIt is covered with a film 9. [0010] In such an LED, a window is used.
The Al mixed crystal ratio of the layer 6 is as high as x = 0.7, and
It is more easily oxidized. As a result, electricity is supplied in humid air.
When the test is performed, an oxide is generated on the surface of the p-type window layer 6 and the oxide is activated.
Light emitted in the layer is absorbed by the relevant part and the light output decreases
There was a problem to do. This oxide also forms over time.
There is also a problem that the element may be destroyed by the stress.
Was. In order to solve this problem, a conventional LED is used.
Is SiO on top and mesa_TwoForming film 9 to protect surface
Was. However, SiO_TwoIn the film, the top surface of the device and the
Step coverage at the edge with the
Or opening the window of the bonding pad in the next process
Because the step coverage of the resist is incomplete in the process,
Exposed SiO_TwoThe film is etched and at edge 10
The window layer 6 is exposed, and an oxide is generated in this portion.
Chip destruction similar to that described above occurred one after another and became a problem. The present invention solves this problem.
In this case, the GaAlAs layer containing Al is prevented from being exposed,
Provide reliable LED and improve luminous efficiency
The purpose is to let. [0013] [MEANS FOR SOLVING THE PROBLEMS]
The LED of the present invention is a semiconductor using a compound semiconductor as a material.
Semiconductor with protective film formed from top to side of light emitting device
A body light emitting element, wherein a top surface periphery of the semiconductor light emitting element
Due to the roundness of the edge, the
Improves Tep coverage, etches protective film
And the top surface of the element can be prevented from being exposed.
Have. [0014] DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention
Is the top surface of a semiconductor light emitting device made of a compound semiconductor
Semiconductor light-emitting device with a protective film formed
Therefore, the edge of the top surface periphery of the semiconductor light emitting element is rounded.
A semiconductor light emitting device characterized by having
The step coverage in the edge area is improved, and the Al mixed crystal ratio is improved.
Of the above oxides caused by the exposure of the high window layer
Not only improves reliability, but also reduces light
The effect is that the extraction efficiency is improved and the brightness can be improved.
Have. FIG. 1 shows an embodiment of the present invention.
This will be described with reference to FIG. FIG. 1 shows a surface light emitting device according to an embodiment of the present invention.
It is principal part sectional drawing of a type | mold LED. Basic structure is the same as before
However, the shape of the edge of the periphery of the top surface of the element and the
Have different surface protective films. Step by step how to fabricate this structure
Will be explained. First, an n-type GaAs substrate is formed on an n-type GaAs substrate 1.
s buffer layer 2, n-type Al_0.35Ga_0.15In_0.5P class
Pad layer 3, Al_0.1Ga_0.4In_0.5P active layer 4, p-type A
l_0.35Ga_0.15In_0.5P clad layer 5, Al mixed crystal ratio x
= 0.7 Zn-doped p-type Al_0.7Ga_0.3As window layer 6
The p-side electrode 7 is formed on the top side and the n-side electrode 8 is formed on the back side.
To form 50 μm around the element by photolithography process
Form a m-wide street and dry etch
To form mesas. Continue (sulfuric acid: hydrogen peroxide solution:
(Water): Etching is performed with water = (1: 1: 100): 1
Roundness is formed at the edge between the top surface of the light emitting element and the mesa
Let it. This etchant etches laterally, so-called
Has roundness due to large loose etching
Etching that can be performed
Generally, if the mesa depth exceeds 10 μm
It is preferably used in combination with dry etching. But mesa depth
When the thickness is as thin as 10 μm or less, sulfuric acid: hydrogen peroxide solution:
Mesa etching with roundness at the element edge using only water
It is possible. Thereafter, the SiO_Two The film 9 is formed by the CVD method.
After the photolithography process, φ100
In order to form a wire bonding pad of μm,
iO _TwoA window opening etching of the film 9 is performed. Thereafter, each chip is divided by dicing.
Let go. The chip is sealed with a resin by an ordinary assembly process.
After stopping, direct current was applied in an atmosphere at a temperature of 85 ° C and a humidity of 85%.
An electric current test at a current of 5 mA was performed. The result is compared with the conventional LED
The results are shown in FIG. In the conventional structure, after assembling as described above,
In a similar test, the emission output P (t)
Ratio P (t) / light emission output P (0) during 0 hours
The present invention was used while P (0) dropped sharply.
A chip that is resin-sealed by the normal assembly process is 1
P (t) / P (0) slightly decreases even after more than 000 hours
I can only see it. FIG. 3 shows a luminance comparison with the conventional structure.
However, the brightness is about 10% higher than the conventional product.
You can see that it is. As described above, the peripheral edge of the element top surface of the element
Step coverage at the edge due to roundness
Improved reliability at high temperatures and high humidity.
At the same time, the luminance can be improved. [0023] As described above, according to the present invention, the compound half
High temperature and high humidity conditions for LED made of conductor
Light emission of the light emitting element over time when current is applied
It is possible to prevent the output from lowering and to improve the luminous efficiency.
it can. In the embodiment of the present invention, AlGa
The case of having an As window layer has been described.
And the like, using a mixed crystal compound semiconductor containing Al as the window layer.
A similar effect is obtained for the child.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a main part of an AlGaInPLED of the present invention. FIG. 2 is a diagram showing a temporal change in light emission output under high temperature and high humidity in the present invention and a conventional structure. FIG. 4 is a cross-sectional view of a main part of a conventional AlGaInPLED. DESCRIPTION OF REFERENCE NUMERALS 1 n-type GaAs substrate 2 n-type GaAs buffer layer 3 n-type AlGaInP cladding layer 4 AlGaInP active layer 5 p-type AlGaInP cladding layer 6 window layer 7 p-side electrode 8 n-side electrode 9 SiO ₂ protective film 10 edge

Claims (1)

Claims: 1. A semiconductor light emitting device having a protective film formed from a top surface to a side surface of a semiconductor light emitting device using a compound semiconductor as a material, wherein an edge portion of a peripheral edge of the top surface of the semiconductor light emitting device is formed. A semiconductor light emitting device having roundness.