JP2000340892A - Compound semiconductor device and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a nitride semiconductor element, which can be operated at a low operating voltage and can be used over a long period and the manufacturing yield of which can be improved. SOLUTION: A compound semiconductor device is manufactured in such a way that an Si-doped n-type Al0.1Ga0.9N clad layer 40 is formed on the surface of an n-type Al0.1Ga0.9N substrate 39 by the MOCVD method at a growing temperature of 1,050 deg.C under a growing pressure of 100 Torrs and an Si-doped n-type GaN light-confining layer 41 is formed on the clad layer 40 at the same growing temperature under a growing pressure of 760 Torrs. Then an undoped MQW layer 42, composed of an In0.2Ga0.8N well layer and an In0.05Ga0.95N barrier layer is grown on the light confining layer 41 at a growing temperature of 780 deg.C and a Mg-doped p-type Al0.2Ga0.8N cap layer 43 is formed on the MQW layer 42 at a growing temperature of 1,050 deg.C under a growing pressure of 70 Torrs. In addition, an Mg-doped p-type GaN light-confining layer 44 is formed on the cap layer 43 under a growing pressure of 760 Torrs and an Mg-doped p-type Al0.1Ga0.9N clad layer 45 is grown on the light confining layer 44 under a growing pressure of 100 Torrs. Moreover, an Mg-doped p-type GaN contact layer 46 is grown on the clad layer 45 under a growing pressure of 1,400 Torrs. Finally, an LD structure is formed by forming a mesa 47, composed of the clad layer 45 and contact layer 46 and an SiO2 insulating film 48 on the clad layer 45 and the mesa 47, and exposing the mesa 47.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a nitride-based compound semiconductor (In (indium) XAl (aluminum) YGa).
(Gallium) 1-X-YN (nitrogen), X ≧ 0, Y ≧ 0, X + Y ≦ 1) The present invention relates to a method of manufacturing an apparatus.

[0002]

2. Description of the Related Art Metal-organic vapor phase epitaxy on nitride-based compound semiconductor laser crystals is carried out by applying a growth pressure as described in APPLIED PHYSISCS LETTERS, Vol. 70, pp. 1417, 1997. At normal pressure (760 Torr), and also in Electronics Letters (ELECTRONICS L
ETTERS), Vol. 34, p. 1494, 1998, there is an example in which the pressure is set to 700 Torr, and all of them achieve room-temperature continuous oscillation.

Further, growth of other nitride-based compound semiconductor laser crystals by metal organic chemical vapor deposition is described in Japanese Journal of Applied Physics (J.
APANESE JOURNAL OF APPLIED PHYSISCS) Volume 38 2B
As described in page 184, 1999, 10
It is performed by a metal organic vapor phase epitaxy method of 0 Torr. The nitride-based compound semiconductor laser formed by this manufacturing method has succeeded in continuous oscillation at room temperature. FIG. 6 shows a cross-sectional structure perpendicular to the substrate surface of the nitride-based compound semiconductor laser.

In FIG. 1, an n-GaN semiconductor substrate 1 is shown.
01 n-type Al0.1 doped with Si (silicon)
An n-type cladding layer 102 made of Ga0.9N (silicon concentration 4 × 10 ¹⁷ , thickness 1 μm) is formed. Also, n
N-type Ga doped with Si
An n-type optical confinement layer 103 made of N (silicon concentration 4 × 10 ¹⁷ , thickness 0.1 μm) is formed.

On the surface of the n-type optical confinement layer 103, a well layer made of In0.2Ga0.8N (thickness: 3 nm) and In well
Undoped MQW (multi-quantum well) layer 104 composed of 0.05 Ga 0.95 N (5 nm thick) barrier layer (3 wells)
) Are formed. Furthermore, the undoped MQW layer 1
A cap layer 105 made of p-type Al0.2Ga0.8N doped with Mg (magnesium) is formed on the surface of the substrate 04.

Further, on the surface of the cap layer 105, p-type GaN doped with Mg (Mg concentration 2 × 1
0 ¹⁷ , 0.1 μm thick) p-type optical confinement layer 10
6 are formed. Further, on the surface of the p-type optical confinement layer 106, Mg-doped p-type Al0.1Ga0.9
A p-type cladding layer 107 made of N (Mg concentration 2 × 10 17, thickness 0.5 μm) is formed.

On the surface of the p-type cladding layer 107, M
g-doped p-type GaN (Mg concentration 2 × 10 17, thickness
0.1 μm) is formed. As described above, each compound semiconductor layer is sequentially grown on the surface of the semiconductor substrate 101 to form an LD (laser diode) structure. The above-described laser diode structure is grown by a 100 Torr reduced pressure MOCVD (metal organic chemical vapor deposition) apparatus.

Ammonia is used as a material for N (nitrogen), and materials for Ga, Al, and In are TMG (trimethylgallium), TMA (trimethylaluminum), and TMI.
(Trimethylindium) is used.

The growth temperature of each compound semiconductor layer described above is
The InGaN MQW active layer 104 was at 780 ° C., and all other compound semiconductor layers were at 1050 ° C. After partially leaving the mesa 109 including the p-type cladding layer 107 and the p-type contact layer 108 by dry etching, an SiO ₂ insulating film 110 is formed, and cueing of the mesa is performed by an exposure technique. A ridge structure was formed.

On the back surface of the n-type semiconductor substrate 101, an n-electrode 111 made of Ti (titanium) / Al is formed, and on the surface of the p-type contact layer 108, Ni (nickel) / Au (gold) is formed. The p electrode 112 was formed. The LD element which is this compound semiconductor device has a threshold current density of 10.9 KA / cm ² and a voltage of 10.5 at room temperature continuous conditions.
V. Thus, semiconductor lasers prototyped at various growth pressures have succeeded in continuous oscillation at room temperature.

[0011]

However, in the above-described method for manufacturing a compound semiconductor device, as can be seen from the sectional view of the conventional semiconductor laser shown in FIG. 6, the semiconductor laser is made of several different materials. It is configured. For this reason, depending on the type of material forming the layer, there is a disadvantage that the characteristics of the semiconductor laser are deteriorated by the growth pressure.

For example, in FIG. 6, it has been clarified by experiments that GaN doped with Mg, which is the p-type contact layer 108, has deteriorated contact characteristics when N in the GaN crystal escapes. In particular, it has been found that in the metal organic chemical vapor deposition (MOCVD) method at 100 Torr, N is easily removed from the GaN crystal during the growth.

In addition, when Al0.1Ga0.9N used for the p-type clad layer 107 and the n-type clad layer 102 is grown at a high growth pressure, an intermediate reaction occurs between ammonia and TMA.
As a result, it has been confirmed that the in-plane distribution of the Al composition and the growth rate is significantly deteriorated, and the in-plane distribution of Mg doping is also deteriorated. This phenomenon is presumed to be due to the fact that the substance produced by the intermediate reaction between ammonia and TMA adsorbs Mg.

[0014] The above-mentioned drawbacks cause the yield of semiconductor lasers to be significantly degraded. Therefore, in the conventional film growth method in which the growth pressure is fixed, 100 T
In the growth of orr under reduced pressure, the p-contact layer 108
Deteriorates. As a result, there is a problem that the operating voltage of the semiconductor laser is increased, and on the other hand, when the growth pressure is increased, the yield of the device is deteriorated.

The present invention has been made in view of such a background, and an object of the present invention is to provide a nitride semiconductor device which does not increase the operating voltage, has a long life, and improves the production yield, and a method of manufacturing the same.

[0016]

According to the first aspect of the present invention,
In a compound semiconductor device manufactured by metal organic chemical vapor deposition, a semiconductor substrate, a plurality of compound semiconductor layers having a similar composition formed sequentially on the upper surface thereof, and a first semiconductor substrate formed on the semiconductor substrate. And a second electrode formed on the uppermost compound semiconductor layer, wherein the pressure of vapor phase growth is different for each compound semiconductor layer.

According to a second aspect of the present invention, in the compound semiconductor device of the first aspect, the compound semiconductor layer is formed of InXA.
It is characterized by being a nitride semiconductor composed of lYGa1-X-YN (X ≧ 0, Y ≧ 0, X + Y ≦ 1).

According to a third aspect of the present invention, in the compound semiconductor device according to the first or second aspect, the compound semiconductor layer is made of InXAlYGa1-X-YN (X ≧ 0, Y
> 0, X + Y ≦ 1), and a nitride semiconductor comprising another compound semiconductor layer on which an InXGa1-XN (X ≦ 1) compound semiconductor not containing Al is grown. A growth pressure of the one compound semiconductor layer is lower than a growth pressure of the other compound semiconductor layer.

According to a fourth aspect of the present invention, in the compound semiconductor device according to the third aspect, the one compound semiconductor layer comprises:
That is, InXAlYGa1-X-YN containing Al (X ≧ 0, Y> 0, X
+ Y ≦ 1) The growth pressure when growing compound semiconductors is 3
It is characterized by being at most 00 Torr.

According to a fifth aspect of the present invention, in the compound semiconductor device according to any one of the first to fourth aspects,
The second electrode is a p-type electrode, and the uppermost compound semiconductor layer formed on the surface of the semiconductor substrate and in contact with the p-type electrode is a p-type InXAlYGa1-X-YN (X ≧ 0, Y>
0, X + Y ≦ 1) A p-contact layer formed of a compound semiconductor, characterized in that the growth pressure of this p-contact layer is higher than the growth pressure of other compound semiconductor layers.

According to a sixth aspect of the present invention, there is provided a method of manufacturing a nitride-based compound semiconductor device by metalorganic vapor phase epitaxy, wherein a plurality of compound semiconductor layers having the same composition are formed on the semiconductor surface by different vapor phase epitaxy pressures. And a step of sequentially forming them.

According to a seventh aspect of the present invention, in the compound semiconductor device according to the sixth aspect, the compound semiconductor layer is formed of InXAlYGa1-X-YN (X ≧ 0, Y ≧ 0, X + Y ≦ 1). A nitride semiconductor.

According to an eighth aspect of the present invention, in the compound semiconductor device according to the sixth or seventh aspect, the compound semiconductor layer is formed of InXAlYGa1-X-YN (X ≧ 0, Y
> 0, X + Y ≦ 1), and a nitride semiconductor comprising another compound semiconductor layer on which an InXGa1-XN (X ≦ 1) compound semiconductor not containing Al is grown. A growth pressure of the one compound semiconductor layer is lower than a growth pressure of the other compound semiconductor layer.

According to a ninth aspect of the present invention, in the compound semiconductor device according to the eighth aspect, the one compound semiconductor layer,
That is, InXAlYGa1-X-YN containing Al (X ≧ 0, Y> 0, X
+ Y ≦ 1) The growth pressure when growing compound semiconductors is 3
It is characterized by being at most 00 Torr.

According to a tenth aspect of the present invention, in the compound semiconductor device according to any one of the sixth to ninth aspects, the second electrode is a p-type electrode and is formed on a surface of the semiconductor substrate. The uppermost compound semiconductor layer in contact with the p-type electrode is formed of a p-type InXAlYGa1-X-YN (X ≧
0, Y> 0, X + Y ≦ 1) a p-contact layer formed of a compound semiconductor, wherein the growth pressure of this p-contact layer is higher than the growth pressure of other compound semiconductor layers. .

In the nitride semiconductor device of the present invention, two or more types of InX formed on a substrate by metal organic chemical vapor deposition are used.
A nitride semiconductor made of AlYGa1-X-YN (X ≧ 0, Y ≧ 0, X + Y ≦ 1), wherein the growth pressure of each layer is different. Also, InXAlYGa1-X-YN (X ≧ 0, Y> 0, X + Y ≦) containing Al formed on the substrate by the metal organic chemical vapor deposition method.
1) A nitride semiconductor consisting of a layer and an InXGa1-XN (X ≦ 1) layer not containing Al, wherein the layer contains InXAlYGa1-X-
The growth pressure of the YN (X ≧ 0, Y> 0, X + Y ≦ 1) layer is lower than the growth pressure of the InXGa1-XN (X ≦ 1) layer not containing Al.

Further, InXAlYGa1-X-YN (X ≧ 0, Y>) containing Al formed on the substrate by metal organic chemical vapor deposition.
0, X + Y ≦ 1) The growth pressure of the layer is 300 Torr or less.
A nitride semiconductor made of two or more kinds of InXAlYGa1-X-YN (X ≧ 0, Y ≧ 0, X + Y ≦ 1) formed on a substrate by metal organic chemical vapor deposition and in contact with a p-electrode p-type InXAlYGa
1-X-YN (X ≧ 0, Y> 0, X + Y ≦ 1) The growth pressure of the p-contact layer is other than InXAlYGa1-X-YN (X ≧ 0, Y> 0, X + Y ≦ 1). It is characterized by being higher than the growth pressure of the layer.

[0028]

Embodiments of the present invention will be described below with reference to the drawings. <First Embodiment> FIG. 1 is a structural sectional view of a semiconductor laser (nitride semiconductor light emitting device) according to a first embodiment of the present invention. The surface of the n-type Al0.1Ga0.9N semiconductor substrate 1 has M
LD (laser diode) formed by OCVD method
The structure and the manufacturing method thereof will be described.

First, the growth pressure is set to 100 Torr, the growth temperature is set to 1050 ° C., and the surface of the n-type Al0.1Ga0.9N semiconductor substrate 1 is doped with Si-doped n-type Al0.1Ga0.9N.
An n-type cladding layer 2 having a silicon concentration of 4 × 10 ¹⁷ and a thickness of 1 μm is formed. And a growth pressure of 760 Torr
At the same growth temperature of 1050 ° C., an n-type optical confinement layer 3 made of Si-doped n-type GaN (silicon concentration 4 × 10 ¹⁷ , thickness 0.1 μm) is formed on the surface of the n-type cladding layer 2. Form.

Here, the growth pressure is set to 760 Torr, the growth temperature is set to 780 ° C., and the surface of the n-type
A well layer of 0.8N (thickness: 3 nm);
Undoped MQW comprising a 5N (5 nm thick) barrier layer
Layer 4 (three wells) is grown. And the growth temperature is 1
The temperature was set to 050 ° C., the growth pressure was reduced to 100 Torr, and the surface of the undoped MQW layer 4 was coated with Mg-doped p-type Al0.2Ga0.8N (Mg concentration 2 × 10 ¹⁷ , thickness 20 nm).
Is formed.

Next, at a growth temperature of 1050 ° C., the growth pressure is increased to 760 Torr, and Mg
Doped p-type GaN (Mg concentration 2 × 10 17, thickness
A p-type optical confinement layer 6 of 0.1 μm) is formed. Then, at a growth temperature of 1050 ° C. and a growth pressure of 10
0 Torr, the surface of the p-type optical confinement layer 6 is doped with Mg
p-type Al0.1Ga0.9N (Mg concentration 2 × 10 ¹⁷ , thickness 0.5μ)
The p-type cladding layer 7 consisting of m) is grown.

Next, at a growth temperature of 1050 ° C., the growth pressure is increased by 760 Torr, and a p-type GaN doped with Mg (Mg concentration: 2 × 10 ¹⁷ , thickness: 0.1 μm) is formed.
A mold contact layer 8 is grown. The LD structure is sequentially formed according to the above-described manufacturing sequence of each layer. Then, after forming a structure in which the mesa 9 including the p-type cladding layer 7 and the p-type contact layer 8 is partially left by dry etching, an SiO ₂ insulating film 10 is laminated, and the cue of the mesa is exposed. A ridge structure (ridge waveguide) was formed by a technique.

On the back surface of the n-type semiconductor substrate, Ti /
An n-electrode 11 made of Al is formed, and a p-type contact layer 8 is formed.
On the surface, a p-electrode 12 made of Ni / Au is formed. In the first embodiment, an n-type Al 0.1
A Ga0.9N substrate was used, but instead sapphire, Si
C, GaN, etc. may be used, and the electrical polarity of the substrate may be p-type or i-type.

Further, in the first embodiment, the AlGaN of the n-type cladding layer 2, the cap layer 5, and the p-type
The growth pressure at the time of formation was 100 Torr.
rr or less, preferably 300 Torr or less. Further, the growth pressure in the layers other than AlGaN is 760 Torr, but may be 300 Torr or more, and may be normal pressure or more.

As described above, according to the semiconductor laser of the first embodiment, AlGa under a low pressure of 300 Torr or less.
By growing the N layer, an intermediate reaction between TMA and ammonia is suppressed. As a result, in-plane non-uniformity such as the Al composition, the growth rate, and the Mg doping concentration in the AlGaN layer is eliminated, and the yield of the nitride semiconductor device in manufacturing can be improved.

Further, according to the semiconductor laser of the first embodiment, the growth pressure is set to 300 when forming the p-type contact layer 8.
By setting the pressure to Torr or more, the effective pressure of the nitrogen source is increased, and a nitride semiconductor with less nitrogen elimination from the AlGaN layer can be realized. When a contact is made between the p-type contact layer 8 and the p-electrode 12 using such a nitride semiconductor AlGaN crystal with little nitrogen loss, the contact resistance value is higher than the contact resistance of the nitrogen-free p-contact layer. Can be kept low (one digit or more compared to the prior art).

<Second Embodiment> FIG. 2 shows a second embodiment of the present invention.
FIG. 2 is a structural sectional view of a nitride semiconductor light emitting device according to an embodiment. In the figure, the surface of the n-type GaN substrate 13 has M
LED (light emitting diode) formed by OCVD method
The structure and the manufacturing method thereof will be described.

First, the growth pressure was set to 100 Torr and the growth temperature was set to 1050 ° C., and the Si-doped n-type Al0.1Ga0.9N (silicon concentration: 4 ×
10 ^{1 7} to form a n-type cladding layer 14 having a thickness of 0.2 [mu] m). Then, increase the growth pressure to 760 Torr,
The growth temperature was set to 780 ° C., and an active layer 15 made of In0.1Ga0.9N (thickness: 20 nm) was formed on the surface of the n-type cladding layer.
Grow.

Next, the growth temperature was set to 1050 ° C., the growth pressure was lowered to 100 Torr, and the surface of the active layer 15 was coated with Mg-doped p-type Al0.1Ga0.9N (Mg concentration 2 × 10 5
¹⁷ , a p-type cladding layer 16 having a thickness of 0.2 μm is formed. Then, at a growth temperature of 1050 ° C., the growth pressure is set to 760 Torr, and a p-type contact layer 17 made of Mg-doped p-type GaN (Mg concentration: 2 × 10 ¹⁷ , thickness: 0.1 μm) is grown. The LED structure is sequentially formed according to the manufacturing order of each layer described above.

Next, on the back surface of the n-type GaN substrate 13,
An n-electrode 18 made of Ti / Al is formed, and a p-electrode 19 made of Ni / Au is formed on the surface of the p-contact layer 17. In the second embodiment, the n-type GaN substrate 13
Although sapphire, SiC, AlGaN, etc. may be used instead, the electrical polarity of the substrate may be p-type or i-type.

Further, in the second embodiment, the growth pressure of AlGaN such as the n-type cladding layer 14 and the p-type cladding layer 16 is set to 100 Torr, but may be 760 Torr or less, preferably 300 Torr or less. .
Furthermore, the growth pressure in the layers other than AlGaN is
Although it was set to 760 Torr, it may be 300 Torr or more.
It may be higher than normal pressure.

As described above, according to the light emitting diode of the second embodiment, the AlG under a low pressure of 300 Torr or less.
By growing the aN layer, an intermediate reaction between TMA and ammonia is suppressed. As a result, in-plane non-uniformity such as the Al composition, the growth rate, and the Mg doping concentration in the AlGaN layer is eliminated, and the yield of the nitride semiconductor device in manufacturing can be improved.

Further, according to the light emitting diode of the second embodiment, the growth pressure is set to 3 during the formation of the p-type contact layer 17.
By setting the pressure to be equal to or higher than 00 Torr, the effective pressure of the nitrogen source is increased, and a nitride semiconductor with less nitrogen elimination from the AlGaN layer can be realized. When a contact is made between the p-type contact layer 17 and the p-electrode 19 using such a nitride semiconductor AlGaN crystal with less nitrogen loss, the contact resistance of the p-contact layer from which nitrogen is released is lower than that of the contact resistance.
Low contact resistance (one digit or more compared to conventional)
It can be suppressed.

<Third Embodiment> FIG. 3 shows a third embodiment of the present invention.
FIG. 3 is a structural sectional view of a semiconductor laser (nitride semiconductor light emitting device) according to the embodiment. In this figure, an n-type Al
An LD (laser diode) structure formed on the surface of a 0.1 Ga 0.9 N substrate 20 by MOCVD and a method of manufacturing the same will be described.

First, the growth pressure was set to 100 Torr, the growth temperature was set to 1050 ° C., and the Si-doped n-type Al0.1Ga0.9N (silicon concentration: 4 × 10 ¹⁷ , An n-type clad layer 21 having a thickness of 1 μm is formed. And the growth pressure is 100 Torr,
At a growth temperature of 1050 ° C., Si-doped n-type GaN (silicon concentration 4 × 10 ¹⁷ ,
An n-type optical confinement layer 22 having a thickness of 0.1 μm is formed.

Next, the growth pressure is set to 100 Torr and the growth temperature is set to 780 ° C., and the surface of the n-type optical confinement layer 22 is
n0.2Ga0.8N (thickness: 3 nm) well layer;
Undoped MQ consisting of a 95N (5 nm thick) barrier layer
A W layer 23 (three wells) is grown. Then, the growth pressure was set to 100 Torr, the growth temperature was set to 1050 ° C., and Mg-doped p-type Al0.2Ga0.8N (Mg concentration 2 × 10 ¹⁷ , thickness 20 nm) was formed on the surface of the undoped MQW layer 23.
Is formed.

Next, at a growth pressure of 100 Torr and a growth temperature of 1050 ° C., a Mg-doped p-type GaN (Mg concentration 2 × 10 ¹⁷ , thickness 0.1 μm) is formed on the surface of the cap layer 24. A mold light confinement layer 25 is formed. Then, the growth pressure is set to 100 Torr and the growth temperature is set to 10
At 50 ° C., Mg-doped p-type Al0.1Ga0.9N (Mg concentration 2 × 10
¹⁷ , a p-type cladding layer 26 having a thickness of 0.5 μm is grown.

Next, at a growth temperature of 1050 ° C. and a growth pressure of 760 Torr, a p-type GaN doped with Mg (Mg concentration 2 × 10 5) was formed on the surface of the p-type cladding layer 26.
¹⁷ , a 0.1 μm thick p-type contact layer 27 is grown. The LD structure is sequentially formed according to the above-described manufacturing sequence of each layer.

After a structure in which the mesa 28 including the p-type cladding layer 26 and the p-type contact layer 27 is partially left is formed by dry etching, an SiO ₂ insulating film 29 is laminated, and the crest of the mesa is found. Was performed by an exposure technique to form a ridge structure.

On the back surface of the n-type Al0.1Ga0.9N substrate 20, an n-electrode 30 made of Ti / Al is formed. Then, on the surface of the p contact layer 27, the p / Ni
The electrode 31 is formed. In the third embodiment described above,
An n-type Al0.1Ga0.9N substrate 20 was used, but instead,
Sapphire, SiC, GaN or the like may be used, and the electrical polarity of the semiconductor substrate may be p-type or i-type. Further, in the third embodiment, the growth pressure of the p-contact layer 27 is set to 760.
Although the pressure was set to Torr, it is desirable that the growth pressure be higher.

As described above, according to the semiconductor laser of the third embodiment, AlGa under a low pressure of 300 Torr or less.
By growing the N layer, an intermediate reaction between TMA and ammonia is suppressed. As a result, in-plane non-uniformity such as the Al composition, the growth rate, and the Mg doping concentration in the AlGaN layer is eliminated, and the yield of the nitride semiconductor device in manufacturing can be improved.

According to the semiconductor laser of the third embodiment, the growth pressure is set to 30 when the p-type contact layer 27 is formed.
By setting the pressure to 0 Torr or more, the effective nitrogen source pressure is increased, and a nitride semiconductor with less nitrogen elimination from the AlGaN layer can be realized. When a contact is made between the p-type contact layer 27 and the p-electrode 31 using such a nitride semiconductor AlGaN crystal with little nitrogen loss, the contact resistance value of the contact is higher than the contact resistance of the nitrogen-free p contact layer. Can be kept low (one digit or more compared to the prior art).

<Fourth Embodiment> FIG. 4 shows a fourth embodiment of the present invention.
FIG. 2 is a structural sectional view of a light emitting diode (nitride semiconductor light emitting device) according to the embodiment. In this figure, n-type Ga
LED formed on the surface of N substrate 32 by MOCVD method
(Light Emitting Diode) The structure and the manufacturing method thereof will be described.

First, the growth pressure was set to 100 Torr and the growth temperature was set to 1050 ° C., and the Si-doped n-type Al0.1Ga0.9N (silicon concentration: 4 ×
10 ^{1 7,} n-type cladding layer 33 having a thickness of 0.2 [mu] m)
Is formed. Then, the growth pressure is set to 100 Torr, the growth temperature is set to 780 ° C., and the surface of the n-type cladding layer 33 is
An active layer 34 of In0.1Ga0.9N (thickness: 20 nm) is grown.

Next, the growth pressure was set to 100 Torr and the growth temperature was set to 1050 ° C., and the Mg-doped p-type Al0.1Ga0.9N (Mg concentration: 2 × 10 ¹⁷ ,
A p-type cladding layer 35 having a thickness of 0.2 μm) is formed. Then, at a growth temperature of 1050 ° C., the growth pressure is increased to 760 Torr, and the surface of the p-type clad layer 35 is
Mg-doped p-type GaN (Mg concentration 2 × 10 ¹⁷ ,
A p-type contact layer 36 having a thickness of 0.1 μm) is grown.

An LED structure is formed according to the above-described manufacturing sequence of each layer. Also, on the back surface of the n-type GaN substrate 32,
An n-electrode 37 made of Ti / Al is formed. Furthermore, p
On the surface of the contact layer 36, a p-electrode 3 of Ni / Au is formed.
8 is formed.

Further, in the fourth embodiment, the n-type GaN substrate 32 is used, but instead, sapphire,
SiC or AlGaN may be used, and the electrical polarity of the semiconductor substrate may be p-type or i-type. Further, in the fourth embodiment, the growth pressure of the p-contact layer 36 is 760 T
Although it was set to orr, it is desirable that the growth pressure be higher.

As described above, according to the light emitting diode of the fourth embodiment, the AlG under the low pressure of 300 Torr or less.
By growing the aN layer, an intermediate reaction between TMA and ammonia is suppressed. As a result, in-plane non-uniformity such as the Al composition, the growth rate, and the Mg doping concentration in the AlGaN layer is eliminated, and the yield of the nitride semiconductor device in manufacturing can be improved.

According to the light emitting diode of the fourth embodiment, the growth pressure is set to 3 during the formation of the p-type contact layer 36.
By setting the pressure to be equal to or higher than 00 Torr, the effective pressure of the nitrogen source is increased, and a nitride semiconductor with less nitrogen elimination from the AlGaN layer can be realized. When a contact is made between the p-type contact layer 36 and the p-electrode 38 using such a nitride semiconductor AlGaN crystal with less nitrogen loss, the contact resistance of the p-contact layer from which nitrogen is released is smaller than that of the contact resistance.
Low contact resistance (one digit or more compared to conventional)
It can be suppressed.

<Fifth Embodiment> FIG. 4 shows a fourth embodiment of the present invention.
FIG. 3 is a structural sectional view of a semiconductor laser (nitride semiconductor light emitting device) according to the embodiment. In this figure, an n-type Al
An LD (laser diode) structure formed on the surface of a 0.1Ga0.9N substrate 39 by the MOCVD method and a manufacturing method thereof will be described.

First, the growth pressure was set to 100 Torr, the growth temperature was set to 1050 ° C., and the Si-doped n-type Al0.1Ga0.9N (silicon concentration: 4 × 10 ¹⁷ , An n-type cladding layer 40 having a thickness of 1 μm is formed. Then, at a growth temperature of 1050 ° C., the growth pressure is increased to 760 Torr, and in the n-type cladding layer 40, the n-type optical confinement layer 41 made of Si-doped n-type GaN (silicon concentration 4 × 10 ¹⁷ , thickness 0.1 μm) Is formed.

Here, the growth temperature is set to 780 ° C., and the growth pressure is 760 Torr, and the surface of the n-type optical confinement layer 41 is
In0.2Ga0.8N (thickness 3nm) well layer and In0.05Ga0.95N
(Thickness 5 nm) Undoped MQW layer 4 comprising barrier layer
2 (3 wells) are grown. And the growth temperature is 1
The temperature was set to 050 ° C., the growth pressure was reduced to 100 Torr, and p-type Al0.2Ga0.8N doped with Mg (Mg concentration 2 × 10 ¹⁷ , thickness 20 nm) was formed on the surface of the undoped MQW layer 42.
Is formed.

Next, at a growth temperature of 1050 ° C., the growth pressure is increased to 760 Torr, and the surface of the cap layer 43 is
Mg-doped p-type GaN (Mg concentration 2 × 10 ¹⁷ ,
A p-type optical confinement layer 44 having a thickness of 0.1 μm is formed. Then, at a growth temperature of 1050 ° C., the growth pressure is reduced to 100 Torr, and p-type Al0.1Ga0.9N doped with Mg (Mg concentration 2 × 10 ¹⁷ , thickness 0.5 μm) is formed on the surface of the p-type optical confinement layer 44. ) Is grown.

Next, at a growth temperature of 1050 ° C., the growth pressure was increased to 1400 Torr, and p-type GaN doped with Mg (Mg concentration 2 × 1) was formed on the surface of the p-type cladding layer 45.
0 ¹⁷ , a thickness of 0.1 μm) is grown. The LD structure is sequentially formed according to the above-described manufacturing sequence of each layer.

The mesa 4 including the p-type cladding layer 45 and the p-type contact layer 46 is dry-etched.
After the formation of the structure partially leaving the SiO ₂ insulating film 4,
8 are stacked, the cue of the mesa portion is performed by an exposure technique,
A ridge structure was formed. Furthermore, n-type Al0.1Ga0.9N
On the back surface of the substrate 39, an n-electrode 49 made of Ti / Al is formed. Then, the Ni / A
A p electrode 50 made of u is formed.

Further, in the fifth embodiment, the n-type Al0.1Ga0.9N substrate 39 is used, but sapphire, SiC, GaN, or the like may be used instead. It may be a type or an i-type.

In addition, in the fifth embodiment, the growth pressure of AlGaN for the n-type cladding layer 40, the cap layer 43, the p-type cladding layer 45, and the like is set to 100 Torr, but 760 To
rr or less, preferably 300 Torr or less. The growth pressure in the layers other than AlGaN is 760 Torr, but may be 300 Torr or higher, and may be normal pressure or higher.

As described above, according to the semiconductor laser of the fourth embodiment, AlGa under a low pressure of 300 Torr or less.
By growing the N layer, an intermediate reaction between TMA and ammonia is suppressed. As a result, in-plane non-uniformity such as the Al composition, the growth rate, and the Mg doping concentration in the AlGaN layer is eliminated, and the yield of the nitride semiconductor device in manufacturing can be improved.

According to the semiconductor laser of the fourth embodiment, the growth pressure is set to 30 when forming the p-type contact layer 46.
By setting the pressure to 0 Torr or more, the effective nitrogen source pressure is increased, and a nitride semiconductor with less nitrogen elimination from the AlGaN layer can be realized. When a contact is made between the p-type contact layer 46 and the p-electrode 50 using such a nitride semiconductor AlGaN crystal with less nitrogen loss, the contact resistance value of the contact is lower than the contact resistance of the nitrogen-released p contact layer. Can be kept low (one digit or more compared to the prior art).

Although the first to fifth embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and the gist of the present invention is as follows. Even if there is a design change or the like within a range not departing from the present invention, it is included in the present invention.

[0071]

As described above, according to the present invention, Al
By growing GaN at a lower pressure, the intermediate reaction between TMA and ammonia is suppressed, and in-plane non-uniformities such as Al composition, growth rate, and Mg doping concentration are eliminated.
The yield of nitride semiconductor devices can be improved.

Further, according to the present invention, by increasing the growth pressure during the formation of the p-contact layer, the effective pressure of the nitrogen source is increased, and a nitride semiconductor with less nitrogen escape can be realized. When a p-type contact electrode is formed using such a nitride semiconductor crystal with little nitrogen elimination, p
The resistance value can be suppressed to about one digit lower than the contact resistance of the contact layer. As a result, the operating voltage of the semiconductor laser, the LED, and the like can be reduced, and the life of the element can be improved. Therefore, according to the present invention, the operating voltage is low, the life is long, the device yield is improved, and a nitride semiconductor device for mass production can be easily realized.

[Brief description of the drawings]

FIG. 1 is a sectional structural view of a semiconductor laser (nitride semiconductor light emitting device) according to a first embodiment of the present invention.

FIG. 2 is a sectional structural view of a light emitting diode (nitride semiconductor light emitting device) according to a second embodiment of the present invention.

FIG. 3 is a sectional structural view of a semiconductor laser (nitride semiconductor light emitting device) according to a third embodiment of the present invention.

FIG. 4 is a sectional structural view of a light emitting diode (nitride semiconductor light emitting device) according to a fourth embodiment of the present invention.

FIG. 5 is a sectional structural view of a light emitting laser (nitride semiconductor light emitting device) according to a fifth embodiment of the present invention.

FIG. 6 is a sectional structural view of a semiconductor laser using a nitride-based compound according to a conventional example.

[Explanation of symbols]

1 n-type substrate 2 n-type cladding layer 3 n-type optical confinement layer 4 MQW active layer 5 p-type cap layer 6 p-type optical confinement layer 7 p-type cladding layer 8 p-type contact layer 9 mesa type 10 SiO ₂ insulating film 11 n Electrode 12 p-electrode 13 n-type substrate 14 n-type cladding layer 15 active layer 16 p-type cladding layer 17 p-type contact layer 18 n-electrode 19 p-electrode 20 n-type substrate 21 n-type cladding layer 22 n-type optical confinement layer 23 MQW active Layer 24 p-type cap layer 25 p-type optical confinement layer 26 p-type cladding layer 27 p-type contact layer 28 mesa type 29 SiO ₂ insulating film 30 n-electrode 31 p-electrode 32 n-type substrate 33 n-type cladding layer 34 active layer 35 p Type cladding layer 36 p-type contact layer 37 n-electrode 38 p-electrode 39 n-type substrate 40 n-type cladding layer 41 n-type light confinement layer 42 MQW active layer 43 p-type cap layer 44 p-type light confinement layer 45 p-type cladding layer 46 p-type contact layer 47 the mesa 48 SiO ₂ insulating 49 n electrode 50 p electrode

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4M104 AA03 AA04 AA07 AA09 BB05 BB14 CC01 DD21 FF03 FF13 GG04 HH15 5F041 AA24 AA44 CA04 CA05 CA33 CA34 CA40 CA46 CA65 CA99 5F073 AA13 AA74 CA07 CA17 CB02 CB04 CB04 CB04 CB04

Claims (10)

[Claims] 1. A compound semiconductor device manufactured by a metal organic chemical vapor deposition method, comprising: a semiconductor substrate; a plurality of compound semiconductor layers having the same composition formed sequentially on an upper surface of the semiconductor substrate; A first electrode formed thereon; and a second electrode formed on the uppermost compound semiconductor layer, wherein the pressure of vapor phase growth differs for each compound semiconductor layer. Compound semiconductor device. 2. The method according to claim 1, wherein the compound semiconductor layer is InXAlYGa1-XY.
2. The compound semiconductor device according to claim 1, wherein the compound semiconductor device is a nitride semiconductor comprising N (X≥0, Y≥0, X + Y≤1). 3. The method according to claim 1, wherein the compound semiconductor layer is made of In containing Al.
One compound semiconductor layer on which a compound semiconductor of XAlYGa1-X-YN (X ≧ 0, Y> 0, X + Y ≦ 1) is grown;
A nitride semiconductor comprising another compound semiconductor layer on which a compound semiconductor of XGa1-XN (X ≦ 1) is grown, wherein the growth pressure of the one compound semiconductor layer is higher than the growth pressure of the other compound semiconductor layer. The compound semiconductor device according to claim 1, wherein the compound semiconductor device is low. 4. The one compound semiconductor layer, ie, Al
4. The compound according to claim 3, wherein a growth pressure for growing a compound semiconductor of InXAlYGa1-X-YN (X ≧ 0, Y> 0, X + Y ≦ 1) containing the compound is 300 Torr or less. Semiconductor device. 5. The semiconductor device according to claim 5, wherein the second electrode is a p-type electrode, and the uppermost compound semiconductor layer formed on the surface of the semiconductor substrate and in contact with the p-type electrode is a p-type InXAlYGa1-X.
A p-contact layer made of a compound semiconductor of -YN (X ≧ 0, Y> 0, X + Y ≦ 1), wherein the growth pressure of this p-contact layer is higher than the growth pressure of other compound semiconductor layers The compound semiconductor device according to claim 1, wherein: 6. A method for manufacturing a nitride-based compound semiconductor device by metalorganic vapor phase epitaxy, wherein a plurality of compound semiconductor layers having the same composition are sequentially formed on a semiconductor surface by different vapor phase epitaxy pressures. A method for manufacturing a compound semiconductor device, comprising the steps of: 7. The method according to claim 1, wherein the compound semiconductor layer is InXAlYGa1-XY.
7. The compound semiconductor device according to claim 6, wherein the compound semiconductor device is a nitride semiconductor composed of N (X≥0, Y≥0, X + Y≤1). 8. The compound semiconductor layer according to claim 1, wherein said compound semiconductor layer contains In containing Al.
One compound semiconductor layer on which a compound semiconductor of XAlYGa1-X-YN (X ≧ 0, Y> 0, X + Y ≦ 1) is grown;
A nitride semiconductor comprising another compound semiconductor layer on which a compound semiconductor of XGa1-XN (X ≦ 1) is grown, wherein the growth pressure of the one compound semiconductor layer is higher than the growth pressure of the other compound semiconductor layer. The compound semiconductor device according to claim 6, wherein the compound semiconductor device is low. 9. The one compound semiconductor layer, that is, Al
9. The compound according to claim 8, wherein a growth pressure for growing a compound semiconductor of InXAlYGa1-X-YN (X ≧ 0, Y> 0, X + Y ≦ 1) containing the compound is 300 Torr or less. Semiconductor device. 10. The semiconductor device according to claim 1, wherein the second electrode is a p-type electrode, and the uppermost compound semiconductor layer formed on the surface of the semiconductor substrate and in contact with the p-type electrode is a p-type InXAlYGa1.
-X-YN (X ≧ 0, Y> 0, X + Y ≦ 1) is a p-contact layer formed of a compound semiconductor, and the growth pressure of this p-contact layer is lower than the growth pressure of other compound semiconductor layers. The compound semiconductor device according to claim 6, wherein the compound semiconductor device is high.