JP3236463B2 - Light emitting diode and method of manufacturing the same - 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 and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, as such a light emitting diode array, there has been the following one.

FIG. 5 is a plan view of such a conventional light-emitting diode array, FIG. 6 is a cross-sectional view of the light-emitting diode array, FIG. 6 (a) is a cross-sectional view taken along the line aa of FIG. 5, and FIG.
FIG. 6 is a sectional view taken along line bb of FIG. 5.

As shown in these figures, the light-emitting diode array is composed of a p-n junction and a p-side electrode 52 formed in an array on a substrate 54 by selective diffusion. The depth (junction depth) of the P-type diffusion layer 53 formed by selective diffusion is usually a uniform depth. Generally, the luminous intensity depends on the junction depth, so that the luminous intensity is set to a depth at which the light amount becomes maximum. In the figure, reference numeral 51 denotes a diffusion prevention film;
Is an n-side electrode.

[0005]

However, in the above-described conventional LED array, when a voltage is applied in the forward direction, a large amount of current is supplied immediately below the electrodes, and the light emission intensity from the junction immediately below the electrodes is reduced to other regions. Become stronger than compared. However, light emission from the junction directly below the electrode is shielded by the electrode,
It does not contribute to the amount of light taken out.

[0006] Further, when current concentrates directly under the electrode, it causes the growth of defects and shortens the life.

An object of the present invention is to provide a light emitting diode capable of improving the luminous efficiency and life of the light emitting diode, and a method of manufacturing the same, in which the above problems are eliminated.

[0008]

Means for Solving the Problems The present invention, in order to achieve the above object, (1) in the Zn in the n-type compound semiconductor substrate selectively diffused comprising light emitting diodes, in a part of the diffusion region Formation
And a Zn layer formed by a diffusion control film.
Surface concentration N _S is 5 × 10 ¹⁸ cm ⁻³ <N _S <1 × 10 ¹⁹ c
a diffusion layer having a shallow junction depth of m ⁻³ ,
A diffusion layer with a deep junction formed around the
A p-side electrode contacting the diffusion layer having a shallow junction depth
Are provided .

( 2 ) In a method of manufacturing a light emitting diode in which Zn is selectively diffused into an n-type compound semiconductor substrate,
Diffusion formed in a part of the diffusion opening in the diffusion opening
Control film is formed, to form a different junction regions depths DOO
Moni, Zn surface concentration of the shallow region junction depth N _S a 5 × 1
Diffusion so that 0 ¹⁸ cm ⁻³ <N _S <1 × 10 ¹⁹ cm ⁻³
A step of forming a region and a step of contacting a p-side electrode with the region having a small junction depth are performed.

( 3 ) In a method for manufacturing a light emitting diode in which Zn is selectively diffused into an n-type compound semiconductor substrate,
Form a diffusion prevention film that protrudes in the center of the diffusion opening,
Forming a diffusion layer by lateral diffusion, removing the diffusion prevention film, and adding p to a region where the diffusion prevention film has been removed. And a step of contacting the side electrodes.

[0011]

(A) According to the light emitting diode described in the above (1), the light emitting diode is formed in a part of the diffusion region and controls the diffusion.
A Zn surface concentration N _S of 5 × 10 ¹⁸
cm ⁻³ <N _S <1 × 10 ¹⁹ cm ⁻³ and shallow junction depth
Formed around the diffusion layer and the diffusion layer having a small junction depth.
Diffusion layer having a large junction depth, and a diffusion layer having a small junction depth.
Since so as to comprise a p-side electrode to contact the can take a good ohmic resistance of the p-side electrode
And without blocking the light emitting region with the p-side electrode,
Further, light can be efficiently extracted, and the luminous efficiency and life of the light emitting diode can be improved.

(B) According to the method of manufacturing a light emitting diode described in the above ( 2 ), the diffusion opening is formed in the diffusion opening.
Form a diffusion control film that is formed in part,
Forming a combined region and a Zn region having a shallow junction depth.
The surface concentration N _S is 5 × 10 ¹⁸ cm ⁻³ <N _S <1 × 10 ¹⁹ c
forming a diffusion region such that m ^-3, the junction
And a step to contact the p-side electrode to the shallow region of the depth
Since as applied, current flows to the surrounding joint region than the junction of the electrode directly below the light is blocked, it is possible to take out light efficiently. In addition, current concentration directly below the electrodes is also reduced, and the life can be improved.

(C) According to the method for manufacturing a light emitting diode described in the above (3) , the portion having a relatively low Zn concentration formed in the diffusion opening by the lateral diffusion is used as the p-side electrode contact region. It is possible to improve the efficiency and the service life.

[0014]

An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a plan view of a light emitting diode showing a first embodiment of the present invention, and FIG. 2 is a sectional view of the light emitting diode.

As shown in these figures, Zn consisting of a shallow diffusion layer 13b having a junction depth (xj) ₁ immediately below the p-side electrode 14 and a deep diffusion layer 13a having a junction depth (xj) ₂ surrounding the diffusion layer 13b. It has a diffusion layer 13.

For example, (Xj) i is approximately 1 μm, and (Xj) s is approximately 5 μm. As will be described later, Zn by vapor phase diffusion
When the LED is diffused at a low concentration and an LED having a uniform diffusion depth of (Xj) s of about 5 μm is produced, the light emission amount becomes maximum, and (Xj) i is about 1/10 of the diffusion depth of about 1 μm. It has been experimentally confirmed that the light emission amount is obtained.

With such a structure, the resistance of the peripheral portion is lower than that immediately below the p-side electrode 14, so that when a voltage is applied in the forward direction, the current supplied from the p-side electrode 14 is 14 rather than the region directly below 14
It becomes easier to flow in the surrounding area. That is, carriers can be efficiently injected into the junction in a region not shielded by the p-side electrode 14, and light can be extracted efficiently. Conversely, the current supplied to the junction immediately below the p-side electrode 14 decreases, and the amount of light that cannot be extracted outside decreases. On the other hand, since the current does not concentrate directly below the p-side electrode 14, the performance can be improved from the viewpoint of the life. 11 is n-type GaAs
s _1-X P _X epitaxial substrate, 12 is a diffusion barrier film (A
1 ₂ O ₃ film) and 15 are Au alloy electrodes as n-side electrodes.

Hereinafter, a method of manufacturing a light emitting diode according to a first embodiment of the present invention will be described.

FIG. 3 is a schematic plan view of the light emitting diode (light emitting portion of the light emitting diode array), and FIG. 4 is a sectional view of a manufacturing process of the light emitting diode.

(1) First, as shown in FIG.
An anti-diffusion film 22 for selective diffusion of Zn, for example, an Al ₂ O ₃ film of 2000 nm is formed on a type compound semiconductor substrate, for example, an n-type GaAs _1-X P _X epitaxial substrate 21 to form diffusion openings 22a in an array. I do. Then, a diffusion control film 23, for example, an Al ₂ O ₃ film is formed to a thickness of 100 ° in accordance with the electrode pattern, and is patterned by photolithography. At this time, the pattern formation of the diffusion control film is set in consideration of the lateral diffusion distance.

(2) Next, as shown in FIG. 4B, a diffusion protective film 24 for protecting the substrate surface in the vapor phase diffusion,
For example, a PSG film 150 ° is deposited, and Zn is diffused by a sealed tube method using a compound or a mixture containing Zn as a gas source. For example, by annealing at 750 ° C. for 6 hours, a junction having a diffusion depth of about 5 μm as a diffusion depth of the diffusion opening 22 a and a diffusion depth of about 1 μm in a region below the diffusion control film 23 is formed. In this diffusion step, it is desirable to substantially limit the Zn surface concentration as follows.

5 × 10 ¹⁸ with diffusion layer 25b having a shallow junction depth
It is desirable that cm ⁻³ <N _S <1 × 10 ¹⁹ cm ⁻³ . this is,
This is because the ohmic contact of the electrode can be taken satisfactorily, and the resistance of the region immediately below the electrode is higher than the resistance of the other region in the diffusion opening 22a. For example, if the diffusion layer 25b having a shallow junction depth is formed so as to have such a value, the sheet resistance becomes 10 times or more as large as the resistance of the diffusion layer 25a having a deep junction depth around the diffusion layer. Part of the current can flow to the junction region other than immediately below the electrode.

(3) Next, as shown in FIG. 4C, after removing the diffusion control film 23 and the diffusion protection film 24, the diffusion layer 25b having a shallow junction depth is added to the Al electrode 26 serving as a p-side electrode. To form The back surface of the substrate is polished and then the Au electrode serving as the n-side electrode is polished.
The alloy electrode 27 is formed and completed.

In the above embodiment, the example in which the Al electrode 26 is in contact with the diffusion layer 25b having a small junction depth formed by the diffusion control film 23 has been described. However, depending on the shape of the electrode, lateral diffusion can be used. It is.

Next, a second embodiment of the present invention will be described.

FIG. 7 is a schematic plan view of a first step of a light emitting diode (light emitting portion of a light emitting diode array) showing a second embodiment of the present invention, and FIG. 8 is a sectional view of a first manufacturing step of the light emitting diode. FIG. 8A is a sectional view taken along line aa of FIG.
8B is a cross-sectional view taken along the line bb of FIG. 7, FIG. 9 is an explanatory diagram of a second manufacturing process of the light emitting diode, and FIG. 9A is a cross section taken along the line aa of FIG. FIG. 9 (a) is a view of FIG.
FIG. 10 is a cross-sectional view taken along the line -b, FIG. 10 is an explanatory view of a third manufacturing process of the light emitting diode, and FIG.
FIG. 10B is a cross-sectional view taken along line -b, and FIG. 10B is a plan view of FIG.

Hereinafter, a method for manufacturing the light emitting diode will be described.

(1) As shown in FIGS. 8 (a) and 8 (b), an anti-diffusion film (Al ₂ O ₃ film) 32 is formed on an n-type GaAs _1-X P _X epitaxial substrate 31 by 2000 μm. An Al ₂ O ₃ film pattern (extending portion) as a diffusion preventing film according to the diffusion opening 32a and the electrode pattern shape
33 is formed by photolithography. In this case, an electrode whose electrode width is smaller than twice the diffusion depth is desirable.

(2) Next, as shown in FIGS. 9A and 9B, after a diffusion protective film 34 is formed, a Zn diffusion region 35 is formed by vapor phase diffusion by a sealed tube method. .

(3) Next, FIGS. 10A and 10
As shown in (b), after removing the diffusion protective film 34, a contact of the Al electrode 36 which is a p-side electrode is made in a partial region in the diffusion opening 32a in the previous step in accordance with the portion formed by the lateral diffusion. Form. Subsequent steps are the same as in the first embodiment, and a description thereof will be omitted. In this case, it is desirable that the contact width of the Al electrode 36 is narrower than the width of the Al ₂ O ₃ film pattern (extended portion) 33 formed by the lateral diffusion.

In the first and second embodiments, examples of Zn diffusion by vapor phase diffusion have been described. However, Zn diffusion by solid phase diffusion may be used.

FIG. 11 and FIG.
It is explanatory drawing of n diffusion.

For example, as shown in FIG. 11, an SiO ₂ film 41 is provided under a diffusion source film (Zn-doped SiO ₂ film) 42, and Zn is diffused into an n-type compound semiconductor substrate 40. Reference numeral 43 denotes an annealing cap. Alternatively, FIG.
As shown in the figure, a diffusion source film (Si
An example in which O ₂ ) 46 is partially used is possible. 47 is a diffusion source film (SiO ₂ ) with a high Zn doping amount,
Reference numeral 48 denotes an annealing cap. However, even in this case, it is necessary to select conditions so that the Zn concentration on the surface of the n-type compound semiconductor substrate 45 under the electrode is lower than the surrounding Zn concentration.

In the above embodiment, an example in which one layer of Al ₂ O ₃ film is present between the electrode and the substrate has been described. However, it is apparent that the effect is not changed even if a film of a different material is laminated as an interlayer insulating film. is there.

In addition, G other than the n-type GaAs _1-X P _X substrate
It is apparent that the present invention can be applied to an LED array manufactured by diffusing Zn into a compound semiconductor substrate such as aAs, GaP, or AlGaAs.

It should be noted that the present invention is not limited to the above-described embodiment, and various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

[0038]

As described above, according to the present invention, the following effects can be obtained.

(1) According to the first aspect of the present invention , the diffusion control film is formed on a part of the diffusion region.
Is formed, the Zn surface concentration N _S is 5 × 10 ¹⁸ cm ^-3 <
A shallow diffusion layer with a junction depth of N _S <1 × 10 ¹⁹ cm ⁻³
And the junction formed around the diffusion layer with a shallow junction depth
The deep diffusion layer and the shallow diffusion layer
Since a p-side electrode for taking tact is provided , p
That the ohmic resistance of the side electrode can be taken well
In addition, without blocking the light emitting region with the p-side electrode,
Light can be efficiently extracted, and the luminous efficiency and life of the light emitting diode can be improved.

(2) According to the second aspect of the invention, the diffusion
Diffusion control formed in the opening part of this diffusion opening
A control film is formed to form junction regions with different depths.
In addition, the Zn surface concentration N _S in the region where the junction depth is shallow is 5 × 10
Diffusion area so that ¹⁸ cm ^-3 <N _S <1 × 10 ¹⁹ cm ^-3
Forming a band. Thus subjected to a step to contact the p-side electrode to shallow the junction depth region, current flows to the surrounding joint region than the junction of the electrode directly below the light is shielded Light can be extracted efficiently. Also,
The current concentration just below the electrode is also reduced, and the life can be improved.

[0041] (3) According to the third aspect of the present invention, to form a diffusion preventing film that projects in the central portion of the diffusion opening, than twice the width of the <br/> diffusion preventing film diffusion depth Small width,
Since a step of forming a diffusion layer by lateral diffusion and a step of removing the diffusion prevention film and making contact with a p-side electrode in a region where the diffusion prevention film has been removed are performed ,
The luminous efficiency and the life can be improved.

[Brief description of the drawings]

FIG. 1 is a plan view of a light emitting diode according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a light emitting diode showing a first embodiment of the present invention.

FIG. 3 is a schematic plan view of a light emitting diode (light emitting portion of a light emitting diode array) showing a first embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating a manufacturing process of the light emitting diode according to the first embodiment of the present invention.

FIG. 5 is a plan view of a conventional light emitting diode array.

FIG. 6 is a sectional view of a conventional light emitting diode array.

FIG. 7 is a schematic plan view of a first step of a light emitting diode (light emitting portion of a light emitting diode array) according to a second embodiment of the present invention.

FIG. 8 is a sectional view of a first manufacturing step of a light emitting diode according to a second embodiment of the present invention.

FIG. 9 is an explanatory diagram of a second manufacturing process of the light emitting diode according to the second embodiment of the present invention.

FIG. 10 is an explanatory diagram of a third manufacturing step of the light-emitting diode according to the second embodiment of the present invention.

FIG. 11 is an explanatory view illustrating formation of a diffusion layer of a light emitting diode according to a third embodiment of the present invention.

FIG. 12 is an explanatory view of forming a diffusion layer of a light emitting diode according to a fourth embodiment of the present invention.

[Explanation of symbols]

11, 21, 31 n-type GaAs _1-X P _X epitaxial substrate 12, 22, 32 Diffusion prevention film (Al ₂ O ₃ film) 13, 35 Zn diffusion region 13a, 25a Deep diffusion layer 13b, 25b Junction depth Diffusion layer having a shallow depth 14 P-side electrode (Al electrode) 15, 27 n-side electrode (Au alloy electrode) 22a, 32a Diffusion opening 23 Diffusion control film (Al ₂ O ₃ film) 24, 34 Diffusion protective film (PSG) Film) 26,36 Al electrode 33 Al ₂ O ₃ film pattern (overhang portion) 40,45 n-type compound semiconductor substrate 41 SiO ₂ film 42 Diffusion source film (Zn-doped SiO ₂ film) 43,48 Annealing cap 46 Zn doping amount Low diffusion source film (SiO ₂ ) 47 High diffusion Zn source film (SiO ₂ )

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-56-40285 (JP, A) JP-A-5-160436 (JP, A) JP-A-5-63231 (JP, A) JP-A-5-63231 314820 (JP, A) JP-A-6-45643 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 33/00

Claims (3)

(57) [Claims] 1. A light emitting diode in which Zn is selectively diffused into an n-type compound semiconductor substrate, comprising: (a) a light emitting diode formed in a part of a diffusion region ;
The Zn surface concentration N _S is 5 × 10
Shallow junction depth of ¹⁸ cm ⁻³ <N _S <1 × 10 ¹⁹ cm ⁻³
And have diffusion layers, junction formed around the shallow diffusion layer of (b)該接Gofuka of
A deep diffusion layer; and (c) a p contacting the diffusion layer with a shallow junction depth.
A light emitting diode comprising a side electrode . 2. A method for manufacturing a light emitting diode, wherein Zn is selectively diffused into an n-type compound semiconductor substrate, comprising: (a) forming a part of the diffusion opening in the diffusion opening;
Diffusion control film is formed that, to form the different junction regions depths, the Zn surface concentration N _S shallow region junction depth
5 × 10 ¹⁸ cm ^-3 <to the ^{_{N S <1 × 10 19 cm}} -3
Method of manufacturing a light emitting diode for forming a diffusion region, characterized by applying the method to contact the p-side electrode to the (b) shallow region of the junction depth. 3. A method for manufacturing a light-emitting diode, wherein Zn is selectively diffused into an n-type compound semiconductor substrate, comprising: (a) forming a diffusion prevention film projecting at a central portion in a diffusion opening; Forming a diffusion layer by lateral diffusion, the step of: (b) removing the diffusion barrier film, and adding a p-side to a region where the diffusion barrier film has been removed. Performing a step of contacting the electrodes.