JPH1032349A - Growing method for semiconductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a growing method of a semiconductor, which can prevent the deterioration of the III-V semiconductor layer in a nitride system containing In, when it is required to grow the III-V compound semiconductor layer in another nitride system on the III-V compound semiconductor layer in the nitride system containing In such as GaInN layer and the growing temperature higher than the growing temperature of the original layer. SOLUTION: When a GaInN/GaN quantum well structure if formed, after a GaInN layer 5 is grown at the growing temperature of 700-850 deg.C, a GaN cap layer 6 is grown at the temperature equivalent to the growing temperature of the GaInN layer 5 so as to cover the surface of the GaInN layer. The thickness of the GaN cap layer 6 is made to be 30nm or more. Thereafter the growing temperature is made to rise up to, e.g. 100 deg.C, and GnN layer 7 is grown. In place of the GaN cap layer 6, an Alx Ga1-x N cap layer (where, 0<x<=1) can be used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for growing a semiconductor, and more particularly to a method for growing a nitrided III-V compound semiconductor layer containing In such as a GaInN layer at a growth temperature higher than the growth temperature. It is suitable for use in the manufacture of a semiconductor device in which a compound III-V compound semiconductor layer needs to be grown, for example, a semiconductor light emitting element.

[0002]

2. Description of the Related Art Nitride (nitride) -based III-V compound semiconductors such as GaN, AlGaN, and GaInN have band gaps ranging from 1.8 eV to 6.2 eV, and emit red to ultraviolet light. In recent years, attention has been paid to the realization of a possible light-emitting element because it is theoretically possible.

[0003] When a light emitting diode (LED) or a semiconductor laser is manufactured from this nitride III-V compound semiconductor, GaN, AlGaN, GaInN, etc. are laminated in multiple layers, and the light emitting layer (active layer) is an n-type. It is necessary to form a structure sandwiched between the cladding layer and the p-type cladding layer. As such a light emitting diode or a semiconductor laser, the light emitting layer has a GaInN / GaN quantum well structure or G light emitting layer.
Some have an aInN / AlGaN quantum well structure.

When the GaInN / GaN quantum well structure or the GaInN / AlGaN quantum well structure is formed, GaN as a barrier layer is formed in order to obtain good crystallinity.
The layer or AlGaN layer needs to be grown at a high temperature of about 1000 ° C., and the GaInN layer serving as the well layer needs to be grown at a low temperature of 850 ° C. or less.

[0005]

However, after a GaInN layer as a well layer is grown at a low temperature of 850 ° C. or less, the growth temperature is raised to about 1000 ° C. to grow a GaN layer or an AlGaN layer as a barrier layer. This causes a problem that the underlying GaInN layer is deteriorated and the light emission intensity is reduced. It is considered that this is because when the growth temperature is increased after the growth of the GaInN layer, the InN of the GaInN layer is decomposed.

The above description relates to the deterioration of the GaInN layer. Similar deterioration can occur in the entire nitride-based III-V compound semiconductor layer containing In.

Accordingly, an object of the present invention is to provide a GaIn
When it is necessary to grow another nitride III-V compound semiconductor layer at a growth temperature higher than the growth temperature on a nitride III-V compound semiconductor layer containing In such as an N layer, An object of the present invention is to provide a semiconductor growth method capable of preventing deterioration of a nitride III-V compound semiconductor layer containing In.

[0008]

In order to achieve the above object, a first invention of the present invention is to provide a nitride-based II containing In.
The nitride-based I containing In on the IV group compound semiconductor layer
At a growth temperature substantially equal to or lower than the growth temperature of the II-V compound semiconductor layer, Al _x Ga ₁ -xN (0
≦ x ≦ 1) is a method for growing a semiconductor, characterized in that a protective film consisting of ≦ x ≦ 1) is grown in vapor phase.

In the first aspect of the present invention, when the protective film is vapor-phase grown at a growth temperature lower than the growth temperature of the nitride-based III-V compound semiconductor layer containing In, the growth temperature is typically Is selected to be 400 to less than 700 ° C.

[0010] The second invention of the present invention is a method for forming a nitride-based III-V compound semiconductor layer containing In at 700 to 850 ° C.
At the growth temperature of Al _x Ga _1-x N (where 0 ≦ x ≦ 1)
A semiconductor growth method characterized in that a protective film made of GaN is grown in a vapor phase.

In a second aspect of the present invention, another nitride-based III-V compound semiconductor layer is formed on a nitride-based III-V compound semiconductor layer containing In at a growth temperature higher than its growth temperature. When growing, from the viewpoint of obtaining good crystallinity while effectively suppressing the decomposition of InN from the nitride-based III-V compound semiconductor layer containing In, the growth temperature is preferably 750 to 800 ° C. And Al _x Ga _1-x N
(Provided that 0 ≦ x ≦ 1) is vapor-phase grown.

In the present invention, typically, Al _x
After vapor-phase growing a protective film made of Ga _1-x N (where 0 ≦ x ≦ 1), the growth temperature is raised to a predetermined temperature higher than the growth temperature of the protective film, and Al _y Ga is formed on the protective film. _1-y N
(Where 0 ≦ y ≦ 1) a layer is vapor-phase grown.

In the present invention, the protective film is, specifically, a GaN layer or an Al _x Ga ₁ -xN layer (where 0 <
x ≦ 1). Here, when the protective film is a GaN layer, from the viewpoint of suppressing the decomposition of InN effectively,
The thickness is 30 nm or more. Also, the protective film is made of Al _x
In the case of a Ga _1-x N layer (where 0 <x ≦ 1),
From a similar viewpoint, preferably, the thickness is set to be equal to or greater than the thickness indicated by a straight line shown in FIG. 8 described later according to the Al composition ratio x. For example, the protective film is made of Al _x Ga with x = 0.13.
If it is a _1-xN layer, its thickness is 10 nm or more.

In the present invention, the nitride-based III-V compound semiconductor layer is specifically composed of N and at least one group III element selected from the group consisting of Al, Ga, In and B. Specific examples of the nitride-based III-V compound semiconductor layers containing In include Ga.
Specific examples of the InN layer that does not contain In include GaN and AlGaN.

In the present invention, a metal-organic chemical vapor deposition (MOCVD) method or a molecular beam epitaxy (MBE) method is typically used for growing a nitride III-V compound semiconductor layer.

According to the method for growing a semiconductor according to the present invention having the above-described structure, the nitride-based III-
The nitride III containing In on the group V compound semiconductor layer
A protective film made of Al _x Ga ₁ -xN (0 ≦ x ≦ 1) at a growth temperature substantially equal to or lower than the growth temperature of the group V compound semiconductor layer, for example, at a temperature of 700 to 850 ° C. Since the phase is grown, the surface of the nitride-based III-V compound semiconductor layer containing In is covered with the protective film. Therefore, even if subsequently grown Al _y Ga _1-y N layer is raised to a nitride III-V compound semiconductor layer containing the In the growth temperature, a nitride containing the In III- InN from group V compound semiconductor layer
Can be suppressed and degradation can be suppressed.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. In all the drawings of the embodiments, the same or corresponding portions are denoted by the same reference numerals.

FIG. 1 is a sectional view for explaining a method of forming a GaInN / GaN quantum well structure according to the first embodiment of the present invention. FIG. 2 shows a growth sequence according to the first embodiment.

In the first embodiment, as shown in FIGS. 1 and 2, first, a c-plane sapphire substrate 1 is placed in a reactor (not shown) of a MOCVD apparatus, and then a carrier gas is placed in the reactor. The surface of the c-plane sapphire substrate 1 is thermally cleaned by, for example, flowing a mixed gas of H ₂ and N ₂ and performing heat treatment at, for example, 1050 ° C. for 20 minutes. Next, after lowering the substrate temperature to, for example, 510 ° C., ammonia (N
H ₃ ) and trimethylgallium (T
MGa, Ga (CH ₃ ) ₃ ) are supplied, and a GaN buffer layer 2 is grown on the c-plane sapphire substrate 1. Next, the supply of TMGa into the reaction furnace is stopped, and while the supply of NH ₃ is kept as it is, the growth temperature is raised to, for example, about 1000 ° C., and then TMGa is supplied again into the reaction furnace to obtain Ga.
The N layer 3 is grown.

Next, the supply of TMGa into the reactor is stopped again, and the growth temperature is set to, for example, 700 to 850 ° C. (for example,
After the temperature is lowered to 760 ° C.), the GaN layer 4 is grown by supplying TMGa into the reactor again. Since the surface of the underlying GaN layer 3 may be contaminated while the growth temperature is lowered, the GaN layer 4 is grown immediately before the next growth of the GaInN layer 5. 5
Is grown on a clean surface. Next, while keeping the growth temperature at 700 to 850 ° C.,
In a reaction furnace, in addition to NH ₃ as an N source, triethylgallium (TEGa, Ga (C ₂ H ₅ )) as a Ga source
₃ ) and trimethylindium (T
MIn, In (CH ₃ ) ₃ ) and supply the GaInN layer 5.
Grow.

Next, the growth temperature is maintained at 700 to 850 as it is.
While maintaining the temperature at 0 ° C., the supply of TMIn into the reaction furnace was stopped, and the Ga source was switched to TMGa.
The N cap layer 6 is grown. Next, NH was introduced into the reactor.
While continuing the supply of ₃ , the growth temperature is set to, for example, about 1
After the temperature is raised to 000 ° C., TMGa is supplied again into the reaction furnace to grow the GaN layer 7. Thus, the intended GaInN / GaN quantum well structure is formed.

It should be noted that when the GaInN layer 5 is grown, the T
The supply amount of EGa is set to, for example, about 1/10 of the supply amount of TMGa during the growth of the GaN layer 3. At this time,
The growth rate of the GaInN layer 5 is one of the growth rate of the GaN layer 3.
It is about / 10. Specifically, for example, the growth rate of the GaN layer 3 is 1.3 μm / h, and the growth rate of the GaInN layer 5 is 0.13 μm / h.

FIG. 3 shows the thickness of the GaN cap layer 6 and the thickness of Ga.
4 shows the relationship with the emission intensity from the quantum well of the InN / GaN quantum well structure. As can be seen from FIG. 3, when the thickness of the GaN cap layer 6 is 30 nm or more, a sufficiently high emission intensity is obtained, which indicates that the deterioration of the GaInN layer 5 as the well layer is suppressed. means.

FIG. 4 shows the relationship between the growth rate of the GaN cap layer 6 and the light emission intensity from the quantum well of the GaInN / GaN quantum well structure. However, the thickness of the GaN cap layer 6 is 40 nm. As can be seen from FIG. 4, the higher the growth rate, the higher the emission intensity. This means that the faster the growth rate, the more effectively the deterioration of the GaInN layer is suppressed.

As described above, according to the first embodiment, the GaN cap layer 6 is grown on the GaInN layer 5 at a growth temperature equal to the growth temperature of the GaInN layer 5, for example, at a growth temperature of 700 to 850 ° C. This GaInN layer 5
The GaN layer 7 is grown by raising the growth temperature to about 1000 ° C. after covering the surface of
Decomposition of InN from the N layer 5 can be prevented and its degradation can be prevented, and deterioration of the emission intensity from the light emitting layer can be prevented.

FIG. 5 is a sectional view for explaining a method of forming a GaInN / AlGaN quantum well structure according to the second embodiment of the present invention. FIG. 6 shows a growth sequence according to the second embodiment.

In the second embodiment, as shown in FIGS. 5 and 6, after the thermal cleaning of the c-plane sapphire substrate 1 is performed at, for example, 1050 ° C. in the same manner as in the first embodiment, For example, the GaN buffer layer 2 is grown at a growth temperature of 510 ° C.

Next, after increasing the growth temperature to about 1000 ° C., in addition to NH ₃ as an N source and TMGa as a Ga source, trimethylaluminum (TMAl, Al (CH _{3 3} ) is supplied to grow the Al _y Ga _1-y N layer 8.

Next, TMGa and TMA were introduced into the reactor.
1 while stopping the supply of NH ₃ and keeping the growth temperature at, for example, 700 to 850 ° C. (for example, 76 ° C.).
After the temperature is lowered to 0 ° C., TMGa is supplied again into the reaction furnace to grow the GaN layer 4. Next, keep the growth temperature at 7
With the temperature maintained at 00 to 850 ° C., in addition to NH ₃ as an N source, TEGa as a Ga source and TMIn as an In source are supplied into the reactor to grow the GaInN layer 5.

Next, the growth temperature is maintained at 700-850.
While the temperature was maintained at 0 ° C., the supply of TMIn into the reactor was stopped, and the Ga source was switched to TMGa.
_A xGa1 _-xN cap layer 9 is grown. Thereafter, the growth temperature is raised to, for example, about 1000 ° C., and Al _y Ga
_{A 1-y} N layer 10 is grown. From the above, the target G
An aInN / AlGaN quantum well structure is formed.

FIG. 7 is a graph showing the relationship between the Al composition ratio x = 0.13 and Al _x
Ga ₁ -xN Cap Layer 9 Thickness and GaInN / AlGa
The relationship with the emission intensity from a quantum well having an N quantum well structure is shown. As can be seen from FIG. 7, when x = 0.13, Al
_When the thickness of the xGa ₁ -xN cap layer 9 is 10 nm or more, a sufficiently high emission intensity is obtained, which means that the deterioration of the GaInN layer 5 as the well layer is suppressed. .

[0032] Figure 8 is required to suppress deterioration of emission intensity Al _x Ga _1-x N of the thickness of the cap layer 9 Al composition ratio x
FIG. By setting the thickness of the Al _x Ga ₁ -xN cap layer 9 to be equal to or greater than the thickness indicated by the straight line in FIG. 8, deterioration of the light emission intensity can be suppressed. FIG. 8 shows that the smaller the Al composition ratio x, the more Al _x Ga ₁ -xN
It can be seen that the cap layer 8 needs to be thick. For example, Al _x Ga _1-x required to suppress the deterioration of the emission intensity
The thickness of the N cap layer 8 is 6 nm when x = 0.2.
However, when x = 0.13, 10 nm and x = 0.
In the case of 05, it is 20 nm. On the other hand, according to the knowledge of the present inventor, when the Al _x Ga ₁ -xN cap layer 9 is thickened to about 40 nm or more, the number of non-emission centers existing therein increases, which is not preferable. From
The upper limit of the thickness of the Al _x Ga ₁ -xN cap layer 9 is 40 nm.
It is considered to be a degree.

As described above, according to the second embodiment, Al _x Ga _{1 -x} is grown on the GaInN layer 5 at a growth temperature equal to the growth temperature of the GaInN layer 5, for example, 700 to 850 ° C. An N cap layer 9 is grown and this Ga
After covering the surface of the InN layer 5, the growth temperature is set to about 1000 ° C.
By growing the Al _y Ga _1-y N layer 10 by raising it, the decomposition of InN from the GaInN layer 5 can be prevented and its degradation can be prevented, and the degradation of the emission intensity from the light emitting layer can be prevented. Can be prevented. Moreover, whereas in the case of using a GaN cap layer should be the thickness of the above 30 nm, for example, x = 0.13 in Al _x
When the Ga _1-x N cap layer 9 is used, its thickness is 10
Since it is sufficient if the thickness is at least nm, the time required for growing the cap layer can be shortened.

FIG. 9 is a sectional view for explaining a method of manufacturing a semiconductor light emitting device according to the third embodiment of the present invention. As shown in FIG. 9, in the method for manufacturing a semiconductor light emitting device according to the third embodiment, as in the first and second embodiments, after performing thermal cleaning of the c-plane sapphire substrate 11, A GaN buffer layer (not shown) is grown on the surface sapphire substrate 11 at a growth temperature of, for example, 510 ° C. Next, the growth temperature is set to about 100, for example.
0 ° C., and the n-type G
aN contact layer 12, n-type AlGaN cladding layer 13
Then, the n-type GaN optical waveguide layer 14 is sequentially grown. Next, the growth temperature is reduced to, for example, 700 to 850 ° C., and the GaI
An nN active layer 15 and a p-type GaN cap layer 16 are sequentially grown. Next, the growth temperature is raised to, for example, about 1000 ° C., and the p-type GaN optical waveguide layer 17, the p-type AlGaN cladding layer 18, and the p-type GaN contact layer 19 are sequentially grown. Here, the n-type GaN contact layer 12, n
The n-type impurity (donor impurity) of the n-type AlGaN cladding layer 13 and the n-type GaN optical waveguide layer 14 is, for example, Si.
To form a p-type GaN cap layer 16, a p-type GaN optical waveguide layer 17, a p-type AlGaN cladding layer 18, and a p-type Ga
P-type impurity (acceptor impurity) in N contact layer 19
For example, Mg or Zn is used.

Although not shown, a p-side electrode is formed on the p-type GaN contact layer 19 and an n-side electrode is formed in contact with the n-type GaN contact layer 12.

According to the third embodiment, GaInN
After growing the p-type GaN cap layer 16 on the active layer 15 at a growth temperature equal to the growth temperature of the GaInN active layer 15, for example, a growth temperature of 700 to 850 ° C., the growth temperature is raised to about 1000 ° C. GaN optical waveguide layer 17,
Since the p-type AlGaN cladding layer 18 and the p-type GaN contact layer 19 are grown, decomposition of InN from the GaInN active layer 15 can be prevented and its degradation can be prevented. Deterioration can be prevented. As a result, a high-power GaN-based semiconductor light emitting device can be realized.

Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above embodiments, and various modifications based on the technical concept of the present invention are possible.

For example, the numerical values, substrates and source gases mentioned in the first, second and third embodiments are merely examples, and different numerical values, substrates and source gases may be used as necessary. . Specifically, instead of the c-plane sapphire substrate 1, a GaN substrate, a SiC substrate, or the like may be used. Further, as a Ga raw material for growing the GaInN layer 5, TMGa may be used instead of TEGa.

In the first embodiment described above, G
Instead of the aN cap layer 6, an Al _x Ga _1-x N cap layer may be used. Similarly, in the second embodiment, a GaN cap layer may be used instead of the Al _x Ga ₁ -xN cap layer. Further, in the third embodiment, instead of the p-type GaN cap layer 16, p-type Al
_An xGa1 _-xN cap layer may be used.

Further, in the third embodiment described above,
Although the present invention has been described for the case where the present invention is applied to the manufacture of a GaN-based semiconductor light emitting device, the present invention may be applied to the manufacture of a GaN-based electron transit device such as a GaN-based field effect transistor (FET).

[0041]

As described above, according to the method for growing a semiconductor according to the present invention, the nitride III-
The nitride III containing In on the group V compound semiconductor layer
A protective film made of Al _x Ga ₁ -xN (0 ≦ x ≦ 1) at a growth temperature substantially equal to or lower than the growth temperature of the group V compound semiconductor layer, for example, at a growth temperature of 700 to 850 ° C. By performing vapor phase growth, another nitride-based III-V compound semiconductor is grown on the In-containing nitride-based III-V compound semiconductor layer at a growth temperature higher than the growth temperature.
When growing a -V compound semiconductor layer, it is possible to prevent the nitride-based III-V compound semiconductor layer containing In from deteriorating.

[Brief description of the drawings]

FIG. 1 illustrates a GaInN /
FIG. 4 is a cross-sectional view for describing a method for forming a GaN quantum well structure.

FIG. 2 is a schematic diagram illustrating a growth sequence according to the first embodiment of the present invention.

FIG. 3 is a schematic diagram illustrating the relationship between the thickness of a GaN cap layer and the emission intensity from a quantum well of a GaInN / GaN quantum well structure according to the first embodiment of the present invention.

FIG. 4 is a schematic diagram illustrating the relationship between the growth rate of a GaN cap layer and the light emission intensity from a quantum well of a GaInN / GaN quantum well structure according to the first embodiment of the present invention.

FIG. 5 shows a graph of GaInN / according to a second embodiment of the present invention;
FIG. 4 is a cross-sectional view for describing a method of forming an AlGaN quantum well structure.

FIG. 6 is a schematic diagram illustrating a growth sequence according to a second embodiment of the present invention.

FIG. 7 shows Al _x Ga according to a second embodiment of the present invention.
_1-x N cap layer (x = 0.13) thickness and GaInN
FIG. 9 is a schematic diagram illustrating a relationship between the intensity of light emitted from a quantum well of the / AlGaN quantum well structure.

FIG. 8 shows Al _x Ga according to a second embodiment of the present invention.
FIG. 4 is a schematic diagram illustrating a relationship between an Al composition ratio of a _1-xN cap layer and a thickness required to suppress deterioration of emission intensity.

FIG. 9 is a cross-sectional view for explaining the method for manufacturing the semiconductor light emitting device according to the third embodiment of the present invention.

[Explanation of symbols]

1, 11 ... c-plane sapphire substrate, 2 ... GaN buffer layer, 3, 4, 7 ... GaN layer, 5 ... GaI
nN layer, 6 ... GaN cap layer, 8, 10 ... A
l _y Ga _1-y N _{layer, 9 ··· Al x Ga 1-} x N cap layer

Claims (14)

[Claims] An Al _x Ga film is formed on a nitride-based III-V compound semiconductor layer containing In at a growth temperature substantially equal to or lower than the growth temperature of the nitride-based III-V compound semiconductor layer containing In. _A method for growing a semiconductor, wherein a protective film made of _1-xN (0 ≦ x ≦ 1) is grown by vapor phase. 2. After growing the protective film in vapor phase, the growth temperature is raised to a predetermined temperature higher than the growth temperature of the protective film, and Al _y Ga _{1 -y} N (0 to 0) is formed on the protective film. ≤y
<1> The method of growing a semiconductor according to claim 1, wherein the layer is grown by vapor phase. 3. The method for growing a semiconductor according to claim 1, wherein said protective film is grown in a vapor phase at a growth temperature of 400 to less than 700 ° C. 4. The semiconductor growth method according to claim 1, wherein said nitride-based III-V compound semiconductor layer containing In is a GaInN layer. 5. The method according to claim 1, wherein said protective film is a GaN layer. 6. The method according to claim 5, wherein the thickness of the GaN layer is 30 nm or more. 7. The method according to claim 1, wherein the protective film is an Al _x Ga ₁ -xN layer (where 0 <x ≦ 1). 8. At a growth temperature of 700 to 850 ° C., Al _x Ga is grown on a nitride-based III-V compound semiconductor layer containing In.
_A method for growing a semiconductor, wherein a protective film made of _1-xN (0 ≦ x ≦ 1) is grown by vapor phase. 9. The method for growing a semiconductor according to claim 8, wherein said protective film is grown in a vapor phase at a growth temperature of 750 to 800 ° C. 10. After growing the protective film in vapor phase, the growth temperature is raised to a predetermined temperature higher than the growth temperature of the protective film, and Al _y Ga _{1 -yN} (0 to 0) is formed on the protective film. ≤
9. The method for growing a semiconductor according to claim 8, wherein y.ltoreq.1) is grown by vapor phase. 11. The method according to claim 8, wherein the nitride-based III-V compound semiconductor layer containing In is a GaInN layer. 12. The method according to claim 8, wherein the protective film is a GaN layer. 13. The method according to claim 12, wherein the thickness of the GaN layer is 30 nm or more. 14. The method according to claim 8, wherein the protective film is an Al _x Ga ₁ -xN layer (where 0 <x ≦ 1).