JP2003218052A - Manufacturing method of semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a semiconductor device which realizes low resistance of a p-type III-V compound semiconductor layer containing nitrogen, without deteriorating the active layer. <P>SOLUTION: A p-type InGaAlN layer 2, an InGaAlN active layer 3 and an n-type InGaAlN layer 4, of which composition is expressed by (Al<SB>x</SB>Ga<SB>1-x</SB>)<SB>y</SB>In<SB>1-y</SB>N (0≤x≤1, 0≤y≤1), are formed on a sapphire substrate 1. In a state of being 'as-grown', Mg is bonded to hydrogen atom in the p-type InGaAlN layer 2. Then, laser beam is irradiated from a rear of the sapphire substrate 1 under nitrogen atmosphere. Resistance is made low by desorption of hydrogen of the p-type InGaAlN layer 2 is realized by emitting a weak laser beam. In the process, sharpness of a dopant profile can be maintained by restraining diffusion of dopant in a lamination part 10. Thereafter, it is also possible to separate the sapphire substrate 1 from the lamination part 10 by the irradiation of a strong laser beam. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device using a nitride semiconductor, which functions as a short wavelength light emitting diode, a short wavelength semiconductor laser, a high temperature / high speed transistor and the like.

[0002]

2. Description of the Related Art Conventionally, since a nitride semiconductor has a large forbidden band width (for example, GaN has a room temperature of about 3.4 eV), a visible light emitting diode in a relatively short wavelength region such as green / blue or white, It is a material that can realize a short-wavelength semiconductor laser that is effective for increasing the capacity of an optical disc.
Nitride semiconductors are widely used especially as active layers of light-emitting diodes, and blue or violet lasers are strongly desired to be commercialized as light sources for reading / writing high density optical disks.

There are some technical breakthroughs behind the great potential for commercialization and mass production of these devices. One of them is the progress of heteroepitaxial growth technology including the introduction of a low temperature buffer layer. When a GaN layer is used, there is no bulk GaN substrate, so crystal growth must be performed on a heterogeneous substrate. Therefore, a sapphire substrate having the same hexagonal crystal structure as the GaN substrate is used, and a metal organic chemical vapor deposition method (Metal Organic Chemical Vapor Deposition) is used on the sapphire substrate.
A method of epitaxially growing a GaN layer by on: MOCVD) is widely adopted. As an example of the method, an amorphous AlN layer or a GaN low-temperature buffer layer is formed on a sapphire substrate, and then CVD is performed at a relatively high temperature to perform epitaxial growth of a III-V group compound semiconductor layer, which is a main part of the device. Forming layers,
It is possible to obtain a semiconductor layer having a flat surface and few crystal defects.

Further, improvement of device structure, clarification of physical phenomenon of crystal growth, and crystal growth technique of mixed crystal such as InGaN and AlGaN have been greatly advanced.

Yet another breakthrough is the realization of low resistance p-type layers. Previously, it was difficult to lower the resistance of the p-type GaN layer in the epitaxial growth layer even if Mg, which is a group II, was doped as a dopant. However, recently, it has been clarified that the resistance can be lowered by performing electron beam irradiation or annealing in a nitrogen gas atmosphere after forming the epitaxial growth layer. Further, as a mechanism thereof, it has been clarified that hydrogen has passivated the impurity atoms in the p-type GaN layer, and thus the desorption of the hydrogen can realize the reduction in resistance of the p-type GaN layer.

Due to the above two breakthroughs, a pn junction having good crystallinity can be obtained with good reproducibility, and a light emitting diode using this is put into practical use, and a semiconductor laser is in the state of being practically close.

A method of manufacturing the above nitride semiconductor device will be described below. 9A to 9C are cross-sectional views showing a method for manufacturing the conventional nitride semiconductor device described above.

First, in the step shown in FIG. 9A, a metal organic chemical vapor deposition method (MO) is formed on the sapphire substrate 101 (wafer), for example.
The composition is (Al _x Ga _1-x ) _y In _{1- y} N (0 ≦ x ≦ 1, 0 ≦ y on the sapphire substrate 101 by using CVD).
An n-type InGaAlN layer 104 having a thickness of about 2 μm represented by ≦ 1) is formed. Here, the n-type InGaAlN layer may be formed after forming a thin amorphous AlN buffer layer having a thickness of about 50 nm at a low temperature of about 500 ° C., for example. Although not shown, the n-type InGaAlN layer 104 is also provided.
Includes an n-type GaN layer or an n-type AlGaN cladding layer. Then, on the n-type InGaAlN layer 104, the composition is (Al _x Ga _1-x ) _y In _1-y N (0 ≦ x ≦
Undoped InGaAl represented by 1, 0 ≦ y ≦ 1)
The N active layer 103 is formed. InGaAlN active layer 10
Reference numeral 3 denotes a region that includes, for example, an InGaN quantum well structure and, in the case of a light emitting diode or a semiconductor laser device, emits blue or bluish purple light in response to current injection. Further, subsequently, on the InGaAlN active layer 103, the composition is (Al _x Ga _1-x ) _y In _1-y N (0 ≦ x ≦
1, 0 ≦ y ≦ 1) and a p-type InG having a thickness of about 2 μm
The aAlN layer 102 is formed. p-type InGaAlN layer 1
02 is a p-type AlGaN cladding layer or p-type GaN
Contains layers. Further, by CVD, p-type InGa
An oxide film cap layer 106 made of silicon oxide is formed on the AlN layer 102.

In the step shown in FIG. 9A, p-type In
Since, for example, Cp ₂ Mg is used to form the GaAlN layer 102, the p-type InGaAlN layer 102 is doped with Mg. In the as-grown state, since the Mg atoms are passivated by hydrogen atoms in the p-type InGaAlN layer 102, the p-type InGaAlN layer 10 is
2 has a high electric resistance. Therefore, p-type InGa
In order to desorb hydrogen from the AlN layer 102, it is usually necessary to perform heat treatment in a gas atmosphere containing no hydrogen.

Next, in the step shown in FIG. 9B, the wafer is taken out of the crystal growth apparatus and introduced into a furnace in a nitrogen gas atmosphere, for example, a lamp heating furnace. Then, by using the heating lamp 10, the wafer is subjected to heat treatment at a temperature of, for example, about 700 ° C. to reduce the resistance of the p-type InGaAlN layer 102.

Next, in the step shown in FIG. 9C, the oxide film cap layer 106 is removed. Then, p-type InGaAl
N layer 102, InGaAlN active layer 103, and n-type In
A semiconductor laser, a light emitting diode, or the like is formed using the GaAlN layer 104.

[0012]

[Patent Document 1] JP-A-11-126758 (abstract)

[Patent Document 2] Japanese Patent Laid-Open No. 11-186174 (Summary)

[0013]

However, the above-mentioned method for manufacturing a nitride semiconductor has the following problems.

The p-type InGaAlN layer 1 shown in FIG. 9B.
In order to sufficiently activate the p-type impurity in 02,
A high temperature of about 800 ° C is required. However, since this temperature is approximately the same as the growth temperature of the InGaAlN active layer 103, the In atoms in the quantum well structure of the InGaAlN active layer 103 are diffused and the InGaAlN active layer 10 is
In some cases, deterioration of 3 occurred. When the heat treatment temperature is lowered to prevent this, the p-type InGaAlN layer 10 is turned on the contrary.
2, the p-type InGaAlN layer 10 has a large resistivity.
2, InGaAlN active layer 103 and n-type InGaAl
There is a problem that the series resistance between the N layers 104 and the contact resistance of the electrode connected to the InGaAlN layer increase. That is, formation of an active layer at low temperature and p-type InGa
There has been a problem that it is difficult to simultaneously achieve low resistance of the AlN layer.

An object of the present invention is to provide a method of manufacturing a semiconductor device capable of reducing the resistance of a nitrogen-containing p-type III-V compound semiconductor layer without degrading the active layer.

[0016]

A method of manufacturing a semiconductor device according to the present invention is a method of manufacturing a semiconductor device having a semiconductor layer formed by epitaxial growth from a single crystal substrate, the method comprising: , A first semiconductor layer made of a III-V group compound containing nitrogen doped with a p-type impurity, and an n-type second semiconductor layer made of a III-V group compound containing nitrogen doped with an n-type impurity A step (a) of forming a laminated film having at least: and irradiating the first semiconductor layer with light having an energy larger than the forbidden band width of the first semiconductor layer to form the first semiconductor layer. The step (b) of activating the p-type impurity therein is included.

According to this method, the energy of the light to be irradiated and the irradiation time can be selected by using the heating by the light irradiation instead of the heating using the radiant heat such as the lamp heating.
The impurities can be efficiently absorbed in the first semiconductor layer where activation is desired. That is, since the first semiconductor layer can be selectively heated, hydrogen can be desorbed from the first semiconductor layer to reduce the resistance without giving thermal damage to the second semiconductor layer. It will be possible.

It is preferable that the light has an energy larger than at least the forbidden band width of the lowermost portion of the first semiconductor layer.

In the step (a), the first semiconductor layer is formed under the second semiconductor layer, and in the step (b), the first semiconductor layer is formed on the back surface of the single crystal substrate. By irradiating the semiconductor layer with the above-mentioned light, it is possible to reliably prevent the second semiconductor layer from being thermally damaged.

In the step (b), the power density or energy of the irradiated light is changed to at least two types to activate the p-type impurities in the first semiconductor layer and to change the first density. The semiconductor layer and the single crystal substrate can be separated from each other.

By further including the step of fixing the transfer substrate to the above-mentioned laminated body, the laminated portion can be separated from the single crystal substrate in the state of being fixed to the transfer substrate. Therefore, the crystal orientations of the transfer substrate and the laminated portion can be adjusted so that the cleavage surface of the transfer substrate and the cleavage surface of the laminated portion are located on a common plane. That is, even if the cleavage planes of the single crystal substrate and the laminated portion do not match, or even if the single crystal substrate is a material that is difficult to cleave, by selecting a material that can be cleaved at the same time as the laminated portion as the transfer substrate. It becomes possible to form a flat cleavage plane on the end face. Therefore, for example, when the semiconductor device is a semiconductor laser, a semiconductor laser having a flat cleaved surface as a resonator surface and a high optical output can be obtained.

In the step (b), after performing the first-stage treatment for activating the p-type impurity in the first semiconductor layer, the power density or energy of light is changed to make the first step. A second stage process for separating the semiconductor layer and the single crystal substrate from each other can be performed.

In that case, after the process of the first step in the step (b) and before the process of the second step, the method further includes the step of fixing the transfer substrate onto the laminate. As described above, the crystal orientations of the transfer substrate and the laminated portion can be adjusted so that the cleaved surface of the transfer substrate and the cleaved surface of the laminated portion are located on a common plane. Can be demonstrated.

In the step (b), the first semiconductor layer is decomposed or altered to form a conductor layer, and the step (b) is performed.
After that, by further including a step of forming an ohmic electrode made of a conductive material on the conductive layer, a low power consumption type semiconductor device having a small contact resistance can be obtained.

In that case, it is preferable to further include a step of etching the surface portion of the conductor layer after the step (b) and before forming the ohmic electrode.

Before the step (a), there is further provided a step of forming a spacer layer having a band gap smaller than that of the single crystal substrate on the single crystal substrate, and in the step (a),
The laminated film is formed on the spacer layer, and in the step (b), the p-type impurities in the first semiconductor layer are activated and the spacer layer and the single crystal substrate are separated from each other. As a result, it is possible to suppress the occurrence of lattice defects and cracks in the semiconductor layer when separating the substrates.

In the step (a), the first semiconductor layer is formed above the second semiconductor layer, and in the step (b), the first semiconductor layer is formed from above the first semiconductor layer. 1
By irradiating the semiconductor layer with the light, it is possible to reduce the resistance of the first semiconductor layer while avoiding thermal damage to the second semiconductor layer as much as possible.

After the step (a), the method further comprises the step of forming a cap layer on the laminated portion, and the step (b) above.
Then, by irradiating the first semiconductor layer with light from above the cap layer, it is possible to avoid the surface roughness of the laminated portion, and to obtain the laminated portion with good flatness.

After the step (b), the step of removing the cap layer, the step of fixing the transfer substrate on the laminated portion, and the step of fixing the transfer substrate or before fixing the transfer substrate are performed. The method further includes the step of irradiating the back surface of the single crystal substrate with light to separate the single crystal substrate from the stacked portion, whereby the resistance of the first semiconductor layer is reduced and the separation of the single crystal substrate is smoothly performed. You can proceed to.

In the step (b), it is preferable that the energy of light emitted from the back surface of the substrate is larger than the energy of light emitted from above the laminated portion.

After the step (b), a contact between the ohmic electrode and the first semiconductor layer is further included by further including a step of forming an ohmic electrode made of a conductive material on the first semiconductor layer. The resistance can be reduced.

In the step (b), the first semiconductor layer is decomposed or altered to form a conductor layer, and the step (b) is performed.
After that, the method further includes a step of forming an ohmic electrode made of a conductive material on the conductor layer, thereby including a conductor layer having a resistance lower than that of the first semiconductor layer, and including the ohmic electrode and the conductor layer. The contact resistance between and can be reduced.

It is preferable that the method further includes a step of etching the surface portion of the conductor layer after the step (b) and before forming the ohmic electrode.

In the step (a), an n-type third semiconductor layer facing the second semiconductor layer with the first semiconductor layer interposed therebetween and having a band gap different from that of the first semiconductor layer is provided. By forming the above-mentioned laminated portion so as to further include, a laminated portion that can be used as each region of the hetero bipolar transistor is obtained.

In this case, since the band gap of the third semiconductor layer is larger than that of the first semiconductor layer and larger than the energy of light, the third semiconductor layer is hardly affected. , It is easy to reach the first semiconductor layer.

The collector region of the bipolar transistor is formed from the first semiconductor layer, the base region of the bipolar transistor is formed from the second semiconductor layer, and the emitter region of the bipolar transistor is formed from the third semiconductor layer. be able to.

In that case, it is preferable that the forbidden band width of the emitter region is larger than the forbidden band width of the base region.

The step (c) is preferably performed in an inert gas atmosphere or a reduced pressure atmosphere.

As the light, p in the first semiconductor layer is used.
When activating the type impurities, a material having energy smaller than the forbidden band width of the second semiconductor layer is used, so that thermal damage to the second semiconductor layer can be reliably avoided.

Since the light source of the light is a laser that oscillates in a pulsed manner, a laser having a relatively large output can be used, and control of energy and irradiation time becomes easy.

As the light, p in the first semiconductor layer is used.
The bright line of a mercury lamp may be used when activating the type impurities.

By heating the single crystal substrate when irradiating with the light, it is possible to relieve the stress in the film caused by the difference in the coefficient of thermal expansion when the spacer layer is formed. In this case, it becomes easy to separate the semiconductor layer formed on the single crystal substrate from the single crystal substrate. In that case, the heating temperature for heating the single crystal substrate is 400 ° C.
It is preferably 750 ° C. or lower.

By irradiating the light beam so that the light beam scans the surface of the single crystal substrate, it becomes easy to separate the single crystal substrate from the laminated portion formed on the large area single crystal substrate. .

In the step (a), Mg or Be can be used as a dopant when forming the first semiconductor layer.

In the step (a), it is necessary to desorb hydrogen from the first semiconductor layer by forming the first semiconductor layer in an atmosphere containing hydrogen.
Even in that case, by applying the present invention, hydrogen can be easily desorbed to reduce the resistance of the first semiconductor layer.

As the single crystal substrate, a sapphire substrate,
SiC substrate, MgO substrate, LiGaO ₂ substrate, LiGa
_x Al _1-x O ₂ (0 ≦ x ≦ 1) mixed crystal substrate and LiAlO
It is preferable to use one substrate selected from the _two substrates. By using the sapphire substrate, it is possible to improve the initial growth and form a group III-V compound semiconductor layer containing nitrogen having good crystallinity thereon. Further, by using the SiC substrate or the LiAlO ₂ substrate, the lattice constant of the single crystal substrate becomes close to that of the III-V group compound semiconductor layer containing nitrogen, so that the single crystal substrate is made of a III-V group compound containing nitrogen with good crystallinity. It is possible to form a semiconductor layer on it.

As the transfer substrate, a Si substrate, GaA
1 selected from s substrate, GaP substrate and InP substrate
By using two substrates, a good cleavage surface can be easily obtained.

[0048]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) FIG.
FIG. 3C is a sectional view showing the method for manufacturing the semiconductor device using the nitride semiconductor according to the first embodiment of the present invention.

First, in the step shown in FIG. 1A, the main surface is
On the (0001) plane of the sapphire substrate 1 (wafer)
For example, using metal organic chemical vapor deposition (MOCVD)
And the composition is (Al_x Ga_1-x )_y In_1-y N (0 ≦ x ≦
1, 0 ≦ y ≦ 1) p-type InG having a thickness of about 3 μm
The aAlN layer 2 is formed. Here, for example, about 500 ℃
Amorphous AlN thin film with a thickness of about 50 nm at low temperature
After forming the phosphor layer or the GaN layer, p-type InGa
The AlN layer 2 may be formed. Although not shown, p
The InGaAlN layer 2 is a p-type GaN layer or a p-type A
It includes an lGaN cladding layer. In this embodiment
Is, for example, a p-type GaN layer, a p-type (Al
_0.1 Ga_0.9 ) N-clad layer and p-type (Al_0.1 Ga
_0.9 )_0.9 In _y0.1 It is formed by stacking N layers.

Then, on the p-type InGaAlN layer 2,
The composition is (Al _x Ga _1-x ) _y In _{1- y} N (0 ≦ x ≦ 1,
An undoped InGaAlN active layer 3 represented by 0 ≦ y ≦ 1) is formed. The InGaAlN active layer 3 includes, for example, an InGaN quantum well structure, and in the case of a light emitting diode or a semiconductor laser, it is a region that emits blue or blue-violet light in response to current injection. Further, subsequently, on the InGaAlN active layer 3, the composition is (Al _x G
a _1-x ) _y In _1-y N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) and an n-type InGaAlN layer 4 having a thickness of about 0.5 μm is formed. The n-type InGaAlN layer 4 includes an n-type AlGaN cladding layer or an n-type GaN layer. As described above, the p-type InGaAlN layer 2, the InGaAlN active layer 3
Then, the laminated portion 10 including the n-type InGaAlN layer 4 is formed.

In the above process, when forming the n-type layer, S
i and Mg are added as dopants when the p-type layer is formed. In addition, hydrogen gas is used as a carrier gas when performing epitaxial growth by MOCVD. In the as-grown state, p-type InGa
Mg is bonded to hydrogen atoms in the AlN layer 2,
Since the p-type impurities in the p-type InGaAlN layer 2 are not activated, the p-type InGaAlN layer 2 has a high electric resistance.

Next, in the step shown in FIG. 1B, a KrF excimer laser (wavelength 248 nm) beam (light flux) is irradiated from the back surface of the sapphire substrate 1 in a nitrogen atmosphere.

FIG. 2 is a diagram showing the temporal change in the output of the irradiation KrF excimer laser. As shown in the figure,
In the first stage, for example, the pulse energy is 50 mJ,
A laser having a pulse width of 5 ms, that is, a laser having a relatively low output and a large pulse width is emitted. Thereby, the p-type I
The nGaAlN layer 2 is heated by absorbing a laser, and hydrogen in the same layer is desorbed from the film, so that the resistance of the p-type InGaAlN layer 2 is reduced.

Subsequently, in the second step, the pulse energy of the laser is increased to 200 mJ and the pulse width is reduced to 10 ns. By the laser irradiation in the second stage, the film is decomposed in the interface region of the p-type InGaAlN layer 2 with the sapphire substrate 1.

Instead of irradiating the laser with the two kinds of clearly distinguishable pulses of the first and second stages, for example, a pulse whose pulse width (time) gradually increases may be used.

In this process, the laser beam (light flux)
Is irradiated so as to scan the inside of the wafer surface, and the entire wafer is covered with the sapphire substrate 1 and the layers 2, 3, and 3 in the laminated portion 10.
In order to alleviate the stress in the film due to the difference in the coefficient of thermal expansion from No. 4, the film is heated to about 500 ° C. This heating temperature is set to 400 in order to exert the stress relieving function within the range in which the characteristics of each layer on the substrate are not deteriorated or largely deformed.
It is preferably in the range of ℃ to 750 ℃.

Then, in the step shown in FIG. 1C, the stacked portion 10 (p-type InGaAlN layer 2, InGaAlN active layer 3 and n-type InGaAlN layer 4) is removed from the sapphire substrate 1.
Are separated (substrate separation). After that, p in the laminated portion 10
Type InGaAlN layer 2, InGaAlN active layer 3 and n
A light emitting diode or a semiconductor laser using the type InGaAlN layer 4 is formed, and a well-known and common technique can be used in the process.

Therefore, in this embodiment, the p-type InGaAl is irradiated by the laser irradiated from the back surface of the sapphire substrate 1.
It is possible to reduce the resistance of the N layer 2. At this time, by adjusting the energy of the laser to be irradiated and the pulse width,
It is possible to avoid heating each layer in the laminated portion 10 to a high temperature. Therefore, it is possible to suppress the diffusion of the dopant in the stacked portion 10 and maintain the steepness of the dopant profile. Therefore, it is possible to realize a device having good characteristics (such as a light emitting diode or a semiconductor laser having good light emitting characteristics).

In the second step of the process shown in FIG. 1B, the power energy and pulse width of the semiconductor laser to be irradiated are changed to change the sapphire substrate 1 and p.
Since the sapphire substrate 1 can be separated at the interface with the type InGaAlN layer 2, it is possible to simultaneously reduce the resistance and separate the substrate.

Further, electrodes can be formed on both the p-type InGaAlN layer 2 and the n-type InGaAlN layer 4 of the laminated portion 10. When the p-type InGaAlN layer 2, the InGaAlN layer 3 and the n-type InGaAlN layer 4 are mounted on the insulating substrate, the p-type InGaAlN layer 2 or the n-type I
InGaAlN located below the nGaAlN layer 4
When forming an electrode in contact with the layer, it is necessary to etch the InGaAlN layer and the InGaAlN active layer located thereabove. On the other hand, in the present embodiment, since such an etching process is not required, it is possible to reduce the chip size and the manufacturing cost.

However, after the step shown in FIG.
Type InGaAlN layer 2, InGaAlN layer 3 and n-type I
The laminated portion 10 made of the nGaAlN layer 4 may be mounted on a Si substrate or the like. In that case, heat dissipation can be improved by selecting a material having a higher thermal conductivity than the sapphire substrate as the material of the substrate. By improving the heat dissipation, it is possible to realize high power operation in a light emitting diode or a semiconductor laser, for example.

In the past, In was deposited on a sapphire substrate.
When forming a GaAlN layer (GaN layer), even if it is undoped, it tends to be n-type, and it was considered difficult to activate impurities unless a p-type layer was formed on the upper surface side. Was an n-type layer. However, in the present invention, since the p-type impurity in the p-type layer can be activated by irradiation with laser light, the p-type layer may be at the bottom or the top of the laminated portion. Therefore, the conductivity type of each layer in the laminated film can be easily selected.

(Second Embodiment) FIGS. 3A to 3D.
FIG. 6A is a cross-sectional view showing the method for manufacturing the semiconductor device using the nitride semiconductor according to the second embodiment of the present invention.

First, in the step shown in FIG. 3A, the composition is changed on the sapphire substrate 1 (wafer) whose main surface is the (0001) plane by, for example, metal organic chemical vapor deposition (MOCVD). (Al _x Ga _1-x ) _y In _1-y N (0 ≦ x ≦
1, 0 ≦ y ≦ 1) and a p-type InG having a thickness of about 2 μm
The aAlN layer 2 is formed. Here, the p-type InGaAlN layer 2 may be formed after forming a thin amorphous AlN buffer layer having a thickness of about 50 nm at a low temperature of about 500 ° C., for example. Although not shown, p-type InGaAlN
Layer 2 includes a p-type GaN layer or a p-type AlGaN cladding layer. Then, on the p-type InGaAlN layer 2, the composition is (Al _x Ga _1-x ) _y In _1-y N (0 ≦ x ≦
Undoped InGaAl represented by 1, 0 ≦ y ≦ 1)
The N active layer 3 is formed. The InGaAlN active layer 3 includes, for example, an InGaN quantum well structure, and in the case of a light emitting diode or a semiconductor laser, it is a region that emits blue or blue-violet light in response to current injection. Further, subsequently, on the InGaAlN active layer 3, the composition is (Al _x
Ga _1-x ) _y In _1-y N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) and an n-type InGaAlN layer 4 having a thickness of about 0.5 μm is formed. The n-type InGaAlN layer 4 is made of n-type AlGaN.
It includes a clad layer or an n-type GaN layer. As described above, the laminated portion 10 including the p-type InGaAlN layer 2, the InGaAlN active layer 3 and the n-type InGaAlN layer 4 is formed.

In the above process, when forming the n-type layer, S
i and Mg are added as dopants when the p-type layer is formed. In addition, hydrogen gas is used as a carrier gas when performing epitaxial growth by MOCVD. In the as-grown state, p-type InGa
Mg is bonded to hydrogen atoms (not activated) in the AlN layer 2, and as a result, p-type InGaAl
The N layer 2 has a high electric resistance.

Next, in a step shown in FIG. 3B, the n-type InGaAlN layer 4 is formed on the Si substrate 5 (transfer substrate) whose main surface is a substantially (001) surface by using a known bonding technique. To glue.

At this time, when a semiconductor laser is manufactured, the InGaAlN layer <
The InGaAlN layer and the Si substrate are adhered to each other so that the 1 1 2 0> direction is parallel to the <110> direction of the Si substrate.

Next, in a step shown in FIG. 3C, a KrF excimer laser beam (wavelength 248 nm) is irradiated from the back surface of the sapphire substrate 1 in a nitrogen atmosphere.
At this time, for example, by irradiating the laser which has been changed to the first and second stages as shown in FIG. 2 in the first embodiment, hydrogen in the p-type InGaAlN layer 2 is desorbed in the first stage. The resistance is reduced, and the sapphire substrate 1 is separated from the InGaAlN layers 3, 4 in the second step.

It should be noted that instead of irradiating the laser with two kinds of clearly distinguishable pulses of the first and second stages, for example, a pulse whose pulse width (time) gradually increases may be used.

In this process, the laser beam (light flux)
Is irradiated so as to scan the inside of the wafer surface, and the entire wafer is covered with 5 in order to reduce the stress in the film due to the difference in the coefficient of thermal expansion between the sapphire substrate 1 and each layer in the laminated portion 10.
It is heated to about 00 ° C. This heating temperature is 400 ° C. or higher and 75 ° C. or higher in order to exert the stress relieving function within the range in which the characteristics of each layer on the substrate are not deteriorated or largely deformed.
It is preferably in the range of 0 ° C or lower.

The optical density of the KrF excimer laser used here is preferably 600 mJ / cm ² or more.

Then, in the step shown in FIG. 3D, the sapphire substrate 1 is separated from the laminated portion 10 (p-type InGaAlN layer 2, InGaAlN active layer 3 and n-type InGaAlN layer 4) and the Si substrate 5 (substrate separation). ).

After the sapphire substrate 1 has been separated by the laser irradiation in the second stage, Si
The substrate 5 may be adhered.

Then, p-type InGaAl in the laminated portion 10
N layer 2, InGaAlN active layer 3 and n-type InGaAl
Although a light emitting diode or a semiconductor laser using the N layer 4 is formed, a well-known and common technique can be used in the process.

Therefore, in the present embodiment, the resistance of the p-type InGaAlN layer 2 can be reduced by the laser emitted from the back surface of the sapphire substrate 1 as in the first embodiment. At this time, it is possible to avoid heating each layer in the stacked unit 10 to a high temperature by adjusting the energy of the laser to be applied and the pulse width. Therefore, it is possible to suppress the diffusion of the dopant in the stacked portion 10 and maintain the steepness of the dopant profile. Therefore, it is possible to realize a device having good characteristics (such as a light emitting diode or a semiconductor laser having good light emitting characteristics).

In the second step of the process shown in FIG. 3C, the sapphire substrates 1 and p are changed by changing the power energy and pulse width of the semiconductor laser to be irradiated.
Since the sapphire substrate 1 can be separated at the interface with the type InGaAlN layer 2, it is possible to simultaneously reduce the resistance and separate the substrate.

In addition, the p-type InGaAlN layer 2, InGa
Since the laminated portion 10 including the AlN active layer 3 and the n-type InGaAlN layer 4 is mounted on the Si substrate 5, it will be described later.
When making a semiconductor laser using this structure,
By adjusting the crystal orientation relationship between each layer (especially InGaAlN active layer 3) in the laminated portion 10 and the Si substrate 5 so that the cleavage planes thereof are substantially coincident with each other, a cleavage plane with good flatness can be obtained. As a result, a good resonator for a semiconductor laser can be obtained. Further, by utilizing the fact that the thermal conductivity of the Si substrate 5 is higher than that of the sapphire substrate 1, it is possible to realize a high-performance semiconductor laser capable of low threshold current or high power operation.

(Third Embodiment) FIGS. 4A to 4C.
FIG. 6A is a cross-sectional view showing the method for manufacturing the semiconductor device using the nitride semiconductor according to the third embodiment of the present invention.

First, in the step shown in FIG. 4A, the composition is changed on the sapphire substrate 1 (wafer) whose main surface is the (0001) plane by, for example, metal organic chemical vapor deposition (MOCVD). (Al _x Ga _1-x ) _y In _1-y N (0 ≦ x ≦
1, 0 ≦ y ≦ 1) n-type InG having a thickness of about 3 μm
The aAlN layer 4 is formed. Here, the n-type InGaAlN layer 4 may be formed after forming a thin amorphous AlN buffer layer having a thickness of about 50 nm at a low temperature of about 500 ° C., for example. Although not shown, n-type InGaAlN
Layer 4 includes an n-type GaN layer or an n-type AlGaN cladding layer. Then, on the n-type InGaAlN layer 4, the composition is (Al _x Ga _1-x ) _y In _1-y N (0 ≦ x ≦
Undoped InGaAl represented by 1, 0 ≦ y ≦ 1)
The N active layer 3 is formed. The InGaAlN active layer 3 includes, for example, an InGaN quantum well structure, and in the case of a light emitting diode or a semiconductor laser, it is a region that emits blue or blue-violet light in response to current injection. Further, subsequently, on the InGaAlN active layer 3, the composition is (Al _x
Ga _1-x ) _y In _1-y N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) and a p-type InGaAlN layer 2 having a thickness of about 0.5 μm is formed. The p-type InGaAlN layer 2 is p-type AlGaN
It includes a clad layer or a p-type GaN layer. As described above, the laminated portion 10 including the p-type InGaAlN layer 2, the InGaAlN active layer 3 and the n-type InGaAlN layer 4 is formed.

Further, on the p-type InGaAlN layer 2,
Thickness of about 100n made of silicon oxide by CVD method
An oxide film cap layer 6 of m is formed.

In the above process, Si is formed when the n-type layer is formed.
However, Mg is added as a dopant in forming the p-type layer. In addition, hydrogen gas is used as a carrier gas when performing epitaxial growth by MOCVD. In the as-grown state, p-type InGaA
Mg is bonded to hydrogen atoms in the 1N layer 2 (not activated), and as a result, the p-type InGaAlN layer 2 has a high electric resistance.

Next, in the step shown in FIG. 4B, a KrF excimer laser beam (wavelength 248 nm) is irradiated from above the oxide film cap layer 6 in a nitrogen atmosphere. Note that the back surface of the sapphire substrate 1 may be irradiated with a KrF excimer laser (wavelength 248 nm) laser.

Here, the output power of the laser is InGaA.
Only the first stage irradiation shown in FIG. 2 in the first embodiment is performed with the level that the 1N layers 2, 3, 4 are not decomposed. That is, a laser having a relatively low output and a large pulse width is emitted. As a result, the p-type InGaAlN layer 2 is heated by absorbing the laser, and hydrogen in the same layer is desorbed from the film, so that the resistance of the p-type InGaAlN layer 2 is reduced.

In this step, the laser beam (light flux)
Is irradiated so as to scan the inside of the wafer surface, and the entire wafer is heated at 500 ° C. in order to reduce stress in the film due to the difference in thermal expansion coefficient between the sapphire substrate 1, each layer in the laminated portion and the oxide film cap layer 6. It is heated to a degree. This heating temperature is required to exert a stress relieving function in a range that does not cause deterioration of the characteristics of each layer on the substrate or large deformation.
It is preferably in the range of 400 ° C. or higher and 750 ° C. or lower.

Next, in the step shown in FIG. 4C, the oxide film cap layer 6 is removed with hydrofluoric acid, for example. After that, a light emitting diode or a semiconductor laser using the p-type InGaAlN layer 2, the InGaAlN active layer 3 and the n-type InGaAlN layer 4 in the laminated portion 10 is formed, and a well-known and common technique can be used in the process.

Therefore, in this embodiment, the p-type InGaAl is irradiated by the laser irradiated through the oxide film cap layer 6.
It is possible to reduce the resistance of the N layer 2. At this time, by adjusting the energy of the laser to be irradiated and the pulse width,
It is possible to avoid heating each layer in the laminated portion 10 to a high temperature. Therefore, it is possible to suppress the diffusion of the dopant in the stacked portion 10 and maintain the steepness of the dopant profile. Therefore, it is possible to realize a device having good characteristics (such as a light emitting diode or a semiconductor laser having good light emitting characteristics).

In addition, in the present embodiment, since the laser irradiation is performed after the oxide film cap layer 6 is formed, a problem such as surface roughness and decomposition due to temperature rise does not occur, and a flat surface is formed. .

(Fourth Embodiment) FIGS. 5A to 5F.
FIG. 9A is a cross-sectional view showing the method for manufacturing the semiconductor device using the nitride semiconductor according to the fourth embodiment of the present invention.

First, in the step shown in FIG. 5A, a composition is formed on the sapphire substrate 1 (wafer) whose main surface is the (0001) plane by, for example, metal organic chemical vapor deposition (MOCVD). (Al _x Ga _1-x ) _y In _1-y N (0 ≦ x ≦
1, 0 ≦ y ≦ 1) n-type InG having a thickness of about 3 μm
The aAlN layer 4 is formed. Here, the n-type InGaAlN layer 4 may be formed after forming a thin amorphous AlN buffer layer having a thickness of about 50 nm at a low temperature of about 500 ° C., for example. Although not shown, n-type InGaAlN
Layer 4 includes an n-type GaN layer or an n-type AlGaN cladding layer. Then, on the n-type InGaAlN layer 4, the composition is (Al _x Ga _1-x ) _y In _1-y N (0 ≦ x ≦
Undoped InGaAl represented by 1, 0 ≦ y ≦ 1)
The N active layer 3 is formed. The InGaAlN active layer 3 includes, for example, an InGaN quantum well structure, and in the case of a light emitting diode or a semiconductor laser, it is a region that emits blue or blue-violet light in response to current injection. Further, subsequently, on the InGaAlN active layer 3, the composition is (Al _x
Ga _1-x ) _y In _1-y N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) and a p-type InGaAlN layer 2 having a thickness of about 0.5 μm is formed. The p-type InGaAlN layer 2 is p-type AlGaN
It includes a clad layer or a p-type GaN layer. As described above, the laminated portion 10 including the p-type InGaAlN layer 2, the InGaAlN active layer 3 and the n-type InGaAlN layer 4 is formed.

Further, on the p-type InGaAlN layer 2,
Thickness of about 100n made of silicon oxide by CVD method
An oxide film cap layer 6 of m is formed.

In the above process, Si is formed when the n-type layer is formed.
However, Mg is added as a dopant in forming the p-type layer. In addition, hydrogen gas is used as a carrier gas when performing epitaxial growth by MOCVD. In the as-grown state, p-type InGaA
Mg is bonded to hydrogen atoms in the 1N layer 2 (not activated), and as a result, the p-type InGaAlN layer 2 has a high electric resistance.

Next, in the step shown in FIG. 5B, a KrF excimer laser beam (wavelength 248 nm) (beam) is irradiated from above the oxide film cap layer 6 in a nitrogen atmosphere.

Here, the output power of the laser is InGaA.
Only the first stage irradiation shown in FIG. 2 in the first embodiment is performed with the level that the 1N layers 2, 3, 4 are not decomposed. That is, a laser having a relatively low output and a large pulse width is emitted. As a result, the p-type InGaAlN layer 2 is heated by absorbing the laser, and hydrogen in the same layer is desorbed from the film, so that the resistance of the p-type InGaAlN layer 2 is reduced.

In this step, the laser beam (light flux)
Is irradiated so as to scan the inside of the wafer surface, and the entire wafer is relieved of stress in the film due to the difference in thermal expansion coefficient between the sapphire substrate 1, each layer in the laminated portion 10 and the oxide film cap layer 6. It is heated to about 500 ° C.
The heating temperature is preferably in the range of 400 ° C. or higher and 750 ° C. or lower in order to exert the stress relieving function in the range in which the characteristics of each layer on the substrate are not deteriorated or largely deformed.

Next, in the step shown in FIG. 5C, the oxide film cap layer 6 is removed with hydrofluoric acid, for example.

Next, in the step shown in FIG. 5D, the p-type InGaAlN layer 2 is formed into a Si substrate 5 (transfer substrate) whose main surface is a substantially (001) surface by using a known bonding technique. To glue.

At this time, when a semiconductor laser is produced, the InGaAlN layer <
The InGaAlN layer and the Si substrate are adhered to each other so that the 1 1 2 0> direction is parallel to the <110> direction of the Si substrate.

Then, in the step shown in FIG. 5E, a KrF excimer laser beam (wavelength 248 nm) is irradiated from the back surface side of the sapphire substrate 1 in a nitrogen atmosphere.

Here, the output power of the laser is InGaA.
Only the second stage irradiation shown in FIG. 2 in the first embodiment is performed with the level that the 1N layers 2, 3 and 4 are not decomposed. That is, a laser with high output and a small pulse width is emitted.

In this step, the laser beam (light flux)
Is irradiated so as to scan the inside of the wafer surface, and the entire wafer is sapphire substrate 1, each layer in the laminated portion 10 and S.
In order to alleviate the stress in the film due to the difference in the coefficient of thermal expansion from the i substrate 5, the film is heated to about 500 ° C. This heating temperature is set to 4 in order to exert the stress mitigating function within a range that does not cause deterioration of the characteristics of each layer on the substrate or large deformation.
It is preferably in the range of 00 ° C or higher and 750 ° C or lower.

The optical density of the KrF excimer laser used here is preferably 600 mJ / cm ² or more.

As a result, as shown in FIG. 5F, the sapphire substrate 1 is separated from the laminated portion 10 (p-type InGaAlN layer 2, InGaAlN active layer 3 and n-type InGaAlN layer 4) and the Si substrate 5 (substrate. Separation).

The Si substrate 5 may be bonded after the sapphire substrate 1 has been separated by the irradiation of laser light.

Then, p-type InGaAl in the laminated portion 10
N layer 2, InGaAlN active layer 3 and n-type InGaAl
Although a light emitting diode or a semiconductor laser using the N layer 4 is formed, a well-known and common technique can be used in the process.

Therefore, in this embodiment, the p-type InGaAl is irradiated by the laser irradiated through the oxide film cap layer 6.
It is possible to reduce the resistance of the N layer 2. At this time, by adjusting the energy of the laser to be irradiated and the pulse width,
It is possible to prevent the laminated portion 10 from being heated to a high temperature. Therefore, it is possible to suppress the diffusion of the dopant in the stacked portion 10 and maintain the steepness of the dopant profile. Therefore, it is possible to realize a device having good characteristics (such as a light emitting diode or a semiconductor laser having good light emitting characteristics).

In addition, in the present embodiment, since the laser irradiation is performed after the oxide film cap layer 6 is formed, a problem such as surface roughening and decomposition due to temperature rise does not occur, and a flat surface is formed. .

The laminated portion 10 (p-type InGaAlN layer 2, InGaAlN layer 3 and n-type InGaAlN layer 4)
Is mounted on the Si substrate 5, so that when a semiconductor laser is produced by utilizing this structure later, InG
By adjusting the crystal orientation relationship between the aAlN layer and the Si substrate so that the cleavage planes of the two layers substantially coincide with each other, a cleavage plane with good flatness can be obtained. As a result, a good resonator for a semiconductor laser can be obtained. Further, by utilizing the fact that the thermal conductivity of the Si substrate 5 is higher than that of the sapphire substrate 1, it is possible to realize a high-performance semiconductor laser capable of low threshold current or high power operation.

(Fifth Embodiment) FIGS. 6A to 6C.
FIG. 9A is a cross-sectional view showing a method of manufacturing a semiconductor device using a nitride semiconductor according to a fifth embodiment of the present invention.

First, in the step shown in FIG. 6A, the main surface is
On the (0001) plane of the sapphire substrate 1 (wafer)
A spacer layer by, for example, RF sputtering.
To form a ZnO layer 13 having a thickness of about 100 nm.
On the ZnO layer 13, for example, metal organic chemical vapor deposition (MOC)
By VD, the composition is (Al_x Ga_1-x )_y In_1-y N
(0 ≦ x ≦ 1, 0 ≦ y ≦ 1) with a thickness of about 3 μm
A p-type InGaAlN layer 2 is formed. Here, for example
Amorphous as thin as 50nm at a low temperature of 500 ℃
After forming the AlN buffer layer, p-type InGaAlN is formed.
The layer 2 may be formed. Although not shown, p-type In
The GaAlN layer 2 is a p-type GaN layer or p-type AlGa.
It includes an N-clad layer. Then, p-type InGaAl
On the N layer 2, the composition is (Al_x Ga_1-x )_y In_1-y N
Undoped I represented by (0 ≦ x ≦ 1, 0 ≦ y ≦ 1)
The nGaAlN active layer 3 is formed. InGaAlN activity
The layer 3 includes, for example, an InGaN quantum well structure,
For light emitting diodes and semiconductor lasers, current injection
A region that emits blue or violet light depending on
It Then, on the InGaAlN active layer 3, a group is formed.
Negative (Al_x Ga_1-x ) _y In_1-y N (0 ≦ x ≦ 1, 0
N-type InGa having a thickness of about 0.5 μm represented by ≦ y ≦ 1)
The AlN layer 4 is formed. The n-type InGaAlN layer 4 is n
Type AlGaN cladding layer or n-type GaN layer
There is. Si is formed when the n-type layer is formed, and Si is formed when the p-type layer is formed.
Mg is added as a dopant, respectively. Since
As described above, the p-type InGaAlN layer 2 and the InGaAlN active layer are
Part 10 composed of the conductive layer 3 and the n-type InGaAlN layer 4
To form.

In the above process, Si is formed when the n-type layer is formed.
However, Mg is added as a dopant in forming the p-type layer. In addition, hydrogen gas is used as a carrier gas when performing epitaxial growth by MOCVD. In the as-grown state, p-type InGaA
Mg is bonded to hydrogen atoms in the 1N layer 2 (not activated), and as a result, the p-type InGaAlN layer 2 has a high electric resistance.

Next, in the step shown in FIG. 6B, a KrF excimer laser (wavelength 248n is emitted from the rear surface of the sapphire substrate 1 by the same method as shown in FIG. 2 under a nitrogen atmosphere.
The beam (light flux) of m) is irradiated.

At this time, in the first stage as shown in FIG. 2, for example, a laser having a pulse energy of 50 mJ and a pulse width of 5 ms, that is, a laser having a relatively low output and a large pulse width is irradiated. As a result, p-type InGaAl
The N layer 2 is heated by absorbing the laser, and hydrogen in the same layer is desorbed from the film, so that the resistance of the p-type InGaAlN layer 2 is reduced. However, with this laser output, the ZnO layer 13
Does not decompose or melt.

Then, in the second step, the pulse energy of the laser is increased to 200 mJ and the pulse width is reduced to 10 ns. By the laser irradiation in the second stage, the film is decomposed in the interface region of the p-type InGaAlN layer 2 with the sapphire substrate 1.

Instead of irradiating the laser with the two kinds of clearly distinguishable pulses of the first and second stages, for example, a pulse whose pulse width (time) gradually increases may be used.

In this process, the laser beam (light flux)
Is irradiated so as to scan the inside of the wafer surface, and the entire wafer is reduced by 50% in order to reduce the stress in the film due to the difference in coefficient of thermal expansion between the sapphire substrate 1 and each layer in the laminated portion 10.
It is heated to about 0 ° C. This heating temperature is 400 ° C. or higher and 750 ° C. or higher in order to exert the stress relieving function within the range in which the characteristics of each layer on the substrate are not deteriorated or largely deformed.
It is preferably in the range of ℃ or less.

Then, in the step shown in FIG. 6C, the sapphire substrate 1 is separated from the stacked portion 10 (p-type InGaAlN layer 2, InGaAlN active layer 3 and n-type InGaAlN layer 4) and the ZnO layer 13 (substrate separation). ). afterwards,
P-type InGaAlN layer 2 and InGaAl in the laminated portion 10
Although a light emitting diode or a semiconductor laser using the N active layer 3 and the n-type InGaAlN layer 4 is formed, a well-known and commonly used technique can be used in the process.

In this embodiment, in the first step (see FIG. 2) of the process shown in FIG. 6B, the ZnO layer 13 is not decomposed or melted depending on the energy of the laser applied. On the other hand, ZnO layer 13 and p-type InGaAl
Since the light absorbed in the N layer 2 is conducted as heat,
The p-type InGaAlN layer 2 is heated, and the resistance of the p-type InGaAlN layer 2 is reduced by desorption of hydrogen. That is,
The same effect as that of the first embodiment can be exhibited.

Moreover, in the present embodiment, the first
In addition to the effects of the above embodiment, the following effects can be exhibited.

The band gap (forbidden band width) of the ZnO layer 13 is 3.27 eV, and the n-type InGaAlN layer 4 is formed.
Band gap of the GaN layer (3.3
9 eV). Therefore, in this embodiment,
In the second step of the process shown in FIG. 6B, the laser light applied to the back surface of the sapphire substrate 1 is mainly absorbed by the ZnO layer 13 and reaches the InGaAlN layers 2, 3 and 4 only slightly. do not do. Therefore, crystal decomposition or melting occurs in the entire ZnO layer 13 or in a region of the ZnO layer 13 near the interface with the sapphire substrate 1, so that the sapphire substrate 1 is separated from the stacked portion 10 and the ZnO layer 13 at a low optical power density. be able to.

Further, since the InGaAlN layers 2, 3 and 4 in the laminated portion 10 are hardly melted, the InGaAlN layers are not melted.
It is possible to suppress the occurrence of crystal defects and cracks in the AlN layers 2, 3 and 4. That is, even if the thickness of the entire laminated portion 10 is 5 μm or less, each layer I in the laminated portion 10
The sapphire substrate 1 can be separated while maintaining good crystallinity of the nGaAlN layers 2, 3, and 4. Further, since the thickness of the entire laminated portion 10 is as thin as about 5 μm, it is possible to reduce the warp of the substrate caused by the difference in the thermal expansion coefficient between each layer in the laminated portion 10 and the sapphire substrate 1 during the substrate cooling after the epitaxial growth. Therefore, it becomes possible to easily and uniformly adhere to a flat Si substrate or the like with good reproducibility.

Here, the low optical power density means, for example, K
When the laser light of the rF excimer laser is used, GaN
GaN when the layers are in direct contact with the sapphire substrate
The threshold power density at which the layers are separated from each other is about 600 mJ / c
Since it is m ² , it means an optical power density of a value smaller than this.

As the spacer layer, amorphous MgO can be used instead of the ZnO layer 13. In that case, since Mg generated by the decomposition of MgO upon irradiation with light serves as a dopant, it becomes easy to adjust the lowermost portion of the laminated portion to be the p-type layer.

(Sixth Embodiment) FIGS. 7A to 7C.
FIG. 9A is a cross-sectional view showing the method for manufacturing the semiconductor device using the nitride semiconductor according to the sixth embodiment of the present invention.

First, in the step shown in FIG. 7A, the main surface is
On the (0001) plane of the sapphire substrate 1 (wafer)
For example, using metal organic chemical vapor deposition (MOCVD)
Thus, the n-type GaN layer 9 having a thickness of about 2 μm is formed. here
Is as thin as about 50 nm at a low temperature of about 500 ° C.
After forming the morphus AlN buffer layer, n-type Ga
The N layer 9 may be formed. In addition, the n-type GaN layer 9 and the
A semi-insulating GaN layer is further provided between the substrate 1 and the air substrate 1.
It may be. Then, on the n-type GaN layer 9, the thickness
After forming the p-type GaN layer 8 of about 0.2 μm, p-type Ga is formed.
N-type Al with a thickness of about 0.5 μm on the N layer_0.1 Ga
_0.9 The N layer 7 is formed. From the above, n-type Al _0.1 Ga
_0.9 The N layer 7, the p-type GaN layer 8 and the n-type GaN layer 9
The laminated portion 11 is formed.

Further, on the n-type Al _0.1 Ga _0.9 N layer 7, a silicon oxide film having a thickness of about 10 is formed by a CVD method.
A 0 nm oxide film cap layer 6 is formed.

In the above process, when forming the n-type layer, S
i and Mg are added as dopants when the p-type layer is formed. In addition, hydrogen gas is used as a carrier gas when performing epitaxial growth by MOCVD. In the as-grown state, p-type InGa
Mg is bonded to hydrogen atoms (not activated) in the AlN layer 2, and as a result, p-type InGaAl
The N layer 2 has a high electric resistance.

Next, in the step shown in FIG. 7B, the third harmonic (wavelength 355 nm, energy 3.49e) of the YAG laser is emitted from above the oxide film cap layer 6 in a nitrogen atmosphere.
A beam (light flux) of (corresponding to V) is emitted. This allows
Hydrogen is released from the p-type GaN layer 8 to selectively activate the p-type impurities in the p-type GaN layer 8 to reduce the resistance. It should be noted that the back surface of the sapphire substrate 1 may be irradiated with the laser of the third harmonic of the YAG laser.

At this time, since the forbidden band width E1 of the Al _0.1 Ga _0.9 N layer is 3.57 eV, the energy of the irradiated laser is not absorbed by the n-type Al _0.1 Ga _0.9 N layer 7 and the forbidden band is not absorbed. P-type Ga having a width E0 of about 3.39 eV
Mostly absorbed by the N layer 8. The output power of the laser is such that desorption of hydrogen occurs in the p-type GaN layer 8, and only the first-stage irradiation shown in FIG. 2 in the first embodiment is performed. That is, a laser having a relatively low output and a small pulse width is emitted.

In this step, the laser beam (light flux)
Is irradiated so as to scan the inside of the wafer surface, and the whole wafer is exposed to 500 in order to reduce the stress in the film due to the difference in the thermal expansion coefficient between the sapphire substrate 1, each layer in the laminated portion 11 and the oxide film cap layer 6. It is heated to about ℃. The heating temperature is preferably in the range of 400 ° C. or higher and 750 ° C. or lower in order to exert the stress relieving function in the range in which the characteristics of each layer on the substrate are not deteriorated or largely deformed.

Next, in the step shown in FIG. 7C, the oxide film cap layer 6 is removed with hydrofluoric acid, for example. Then, a heterojunction bipolar transistor (HB) having the n-type GaN layer 9 as a collector region, the p-type GaN layer 8 as a base region, and the n-type Al _0.1 Ga _0.9 N layer 7 as an emitter region is used.
T) is formed, and a well-known conventional technique can be used in the process.

The light emitted in the step shown in FIG. 7B is emitted from the 365 nm bright line of the mercury lamp (energy 3.4).
(eV equivalent), the bright line shows the Al _0.1 Ga _0.9 N layer 7
And is absorbed by the p-type GaN layer 8, the same effect as this embodiment can be obtained.

In the present embodiment, the resistance of the p-type GaN layer 8 can be reduced by the laser irradiated through the oxide film cap layer 6. At this time, it is possible to avoid heating each layer (particularly the Al _0.1 Ga _0.9 N layer 7) in the laminated portion 11 to a high temperature by adjusting the energy and pulse width of the laser to be irradiated, so that the hetero bipolar transistor It is possible to realize a high-concentration p-type base region while maintaining a steep impurity concentration profile in each layer (especially the emitter region) therein.

Further, since the laser irradiation is performed after the cap layer is formed, n-type Al _0.1 G due to the temperature rise is formed.
_Problems such as surface roughness and decomposition of the a _0.9 N layer 7 can be avoided, and a heterobipolar transistor having a flat surface can be realized.

After activation of the p-type impurities in the pGaN layer 8, a step of irradiating the back surface of the sapphire substrate 1 with a KrF excimer laser (248 nm) to separate the sapphire substrate 1 may be included.

(Seventh Embodiment) FIGS. 8A to 8D.
FIG. 11A is a cross-sectional view showing the method for manufacturing the semiconductor device using the nitride semiconductor according to the seventh embodiment of the present invention.

First, in the step shown in FIG. 8A, the main surface is
On the (0001) plane of the sapphire substrate 1 (wafer)
For example, using metal organic chemical vapor deposition (MOCVD)
N-type Al with a thickness of about 0.5 μm_0.1 Ga_0.9 N layer 7
Form. Here, for example, at a low temperature of 500 ° C.
Amorphous AlN buffer layer as thin as about nm is formed.
N-type Al after_0.1 Ga_0.9 You may form the N layer 7.
Yes. In addition, n-type Al_0.1 Ga _0.9 N layer 7 and sapphire base
A semi-insulating GaN layer is further provided between the plate 1 and
Good. Then, n-type Al_0.1 Ga_0.9 On the N layer 7,
A p-type GaN layer 8 having a thickness of 0.2 μm and an n having a thickness of about 2 μm
The type GaN layer 9 is sequentially formed. From the above, n-type Al
_0.1 Ga_0.9 N layer 7, p-type GaN layer 8 and n-type GaN layer
A laminated portion 11 made of 9 is formed.

In the above process, when forming the n-type layer, S
i and Mg are added as dopants when the p-type layer is formed. In addition, hydrogen gas is used as a carrier gas when performing epitaxial growth by MOCVD. In the as-grown state, p-type InGa
Mg is bonded to hydrogen atoms (not activated) in the AlN layer 2, and as a result, p-type InGaAl
The N layer 2 has a high electric resistance.

Next, in the step shown in FIG. 8B, Si having a (001) plane as the main surface is formed by using, for example, a bonding technique.
The substrate 5 is adhered to the n-type GaN layer 9.

Next, in the step shown in FIG. 8C, the third harmonic of the YAG laser (wavelength 355 nm, energy 3.49 eV) is applied from the back surface of the sapphire substrate 1 in a nitrogen atmosphere.
(Corresponding to (1)) (beam) is radiated by changing the output and the time in two steps, as in the first embodiment.

At this time, in the stage corresponding to the first stage shown in FIG. 2, desorption of hydrogen in the p-type GaN layer 8 is caused to selectively activate the p-type impurities in the p-type GaN layer 8. To lower the resistance. Forbidden band width E of Al _0.1 Ga _0.9 N layer
Since 1 is 3.57 eV, the energy of the irradiated laser is not absorbed by the n-type Al _0.1 Ga _0.9 N layer 7 and is mostly absorbed by the p-type GaN layer 8 having a forbidden band width E0 of about 3.39 eV. Be absorbed. The output power of the laser is a level required for desorption of hydrogen in the p-type GaN layer 8, and is similar to the first step shown in FIG. 2 in the first embodiment, and has a relatively low output and a pulse width. A large laser.

Then, in the second step, a KrF excimer laser (248 nm, energy 5 eV) having large energy is used.
Equivalent to))) is used to increase the power density of the laser and to reduce the pulse width compared to the first step. By the laser irradiation in this second stage, the n-type Al _0.1 Ga _0.9 N layer 7 is formed.
Of these, the film is decomposed in the interface region with the sapphire substrate 1.

In this step, the laser beam (light flux)
Is irradiated so as to scan the inside of the wafer surface, and the whole wafer is exposed to stress in the film due to the difference in thermal expansion coefficient between the sapphire substrate 1, the n-type Al _0.1 Ga _0.9 N layer 7, the GaN layers 8 and 9 and the Si substrate 5. Is heated to about 500 ° C. The heating temperature is preferably in the range of 400 ° C. or higher and 750 ° C. or lower in order to exert the stress relieving function in the range in which the characteristics of each layer on the substrate are not deteriorated or largely deformed.

Then, by irradiation with the KrF laser, the result shown in FIG.
As shown in (d), the sapphire substrate 1 has the laminated portion 11
(N-type Al _0.1 Ga _0.9 N layer 7, GaN layers 8 and 9 and Si substrate 5). That is, on the Si substrate 5, the n-type GaN layer 9, the p-type GaN layer 8 and the n-type Al _0.1
A structure is obtained in which the Ga _0.9 N layers 7 are sequentially stacked.

After that, the n-type GaN layer 9 is used as a collector region, the p-type GaN layer 8 is used as a base region, and n-type Al _0.1 G is used.
Although a heterojunction bipolar transistor (HBT) having the a _0.9 N layer 7 as an emitter region is formed, a well-known and common technique can be used in the process.

FIG. 9 is a sectional view showing the structure of a heterojunction bipolar transistor formed by the manufacturing process of the seventh embodiment.

As shown in the figure, this heterojunction bipolar transistor has an n-type GaN layer 9 (collector layer).
Of the back surface electrode 21 made of a Ti film and an Al film covering the lower surface of the p-type GaN layer 8 (base layer) and contacting the p-type GaN layer 8 with the Ni film and covering the same. Base electrode 22 made of Au film and n-type Al
_The emitter layer 23 is formed by patterning the _0.1 Ga _0.9 N layer 7, and the emitter electrode 24 is provided on the emitter layer 23 and is in contact with the emitter layer 23. The emitter electrode 24 is made of an Al film covering the Ti film. ing. That is, FIG.
An npn-type bipolar transistor is constituted by the structure shown in FIG.

Even if the light irradiated in the first step of the process shown in FIG. 8C is a 365 nm bright line (corresponding to energy of 3.4 eV) of a mercury lamp, the bright line is Al _0.1 Ga.
_Since it passes through the _0.9 N layer 7 and is absorbed by the p-type GaN layer 8, the same effect as this embodiment can be obtained.

Alternatively, the sapphire substrate 1 may be separated by irradiation with laser light, and then the Si substrate 5 may be bonded.

In this embodiment, it is possible to reduce the resistance of the p-type GaN layer 8 by the laser emitted from the back surface of the sapphire substrate 1. At this time, it is possible to prevent the n-type GaN layer 9 from being heated to a high temperature by adjusting the energy of the laser to be applied and the pulse width, so that a hetero-bipolar transistor having a sharp impurity concentration profile in the emitter region is realized. It becomes possible to do.

By adhering a substrate such as the Si substrate 5 having good heat dissipation to the n-type GaN layer 9, high power operation of the hetero bipolar transistor becomes possible.

Furthermore, according to the heterojunction bipolar transistor of this embodiment, a contact resistance at the base electrode is reduced, a base resistance is small, and a heterojunction bipolar transistor excellent in high frequency characteristics can be obtained.

(Eighth Embodiment) FIGS. 11A to 11D.
FIG. 11A is a cross-sectional view showing the method for manufacturing the semiconductor device using the nitride semiconductor according to the eighth embodiment of the present invention.

First, in the step shown in FIG. 11A, the composition is changed on the sapphire substrate 1 (wafer) whose main surface is the (0001) plane by, for example, metal organic chemical vapor deposition (MOCVD). (Al _x Ga _1-x ) _y In _1-y N (0 ≦ x ≦
1, 0 ≦ y ≦ 1) n-type InG having a thickness of about 3 μm
The aAlN layer 4 is formed. Here, the n-type InGaAlN layer 2 may be formed after forming a thin amorphous AlN buffer layer (or GaN buffer layer) with a thickness of about 50 nm at a low temperature of about 500 ° C., for example. Although not shown, the n-type InGaAlN layer 4 includes an n-type GaN layer or an n-type AlGaN cladding layer. Then, n
On the type InGaAlN layer 4, the composition is (Al _x Ga
An undoped InGaAlN active layer 3 represented by _1-x ) _y In _1-y N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) is formed.
The InGaAlN active layer 3 includes, for example, an InGaN quantum well structure, and in the case of a light emitting diode or a semiconductor laser, it is a region that emits blue or blue-violet light in response to current injection. Further subsequently, on the InGaAlN active layer 3, the composition is _{(Al x Ga 1-x)} y In 1-y N
Thickness represented by (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) about 0.5 μ
A p-type InGaAlN layer 2 of m is formed. p-type InGa
The AlN layer 2 includes a p-type AlGaN clad layer or a p-type GaN layer. From the above, p-type InGaAl
N layer 2, InGaAlN active layer 3 and n-type InGaAl
The laminated portion 10 including the N layer 4 is formed.

In the above process, Si is used when the n-type layer is formed.
However, Mg is added as a dopant in forming the p-type layer. In addition, hydrogen gas is used as a carrier gas when performing epitaxial growth by MOCVD. In the as-grown state, p-type InGaA
Mg is bonded to hydrogen atoms in the 1N layer 2 (not activated), and as a result, the p-type InGaAlN layer 2 has a high electric resistance.

Next, in the step shown in FIG. 11B, the p-type InGaAlN layer 2 is irradiated with a beam (light flux) of a KrF excimer laser (wavelength 248 nm) from above in a nitrogen atmosphere.

Here, the power density and pulse width of the laser are set so that the InGaAlN layers 2, 3 and 4 are not decomposed, and only the first stage irradiation shown in FIG. 2 in the first embodiment is performed. That is, a laser having a relatively low output and a large pulse width is emitted. Thereby, p-type InGaAlN
The layer 2 is heated by absorbing the laser, and hydrogen in the layer is released from the film, so that the resistance of the p-type InGaAlN layer 2 is reduced.

In this step, the laser beam (light flux)
Is irradiated so as to scan the inside of the wafer surface, and the entire wafer is reduced to 50% in order to reduce the stress in the film due to the difference in the coefficient of thermal expansion of each layer in the sapphire substrate 1 and the laminated portion 10.
It is heated to about 0 ° C. This heating temperature is 400 ° C. or higher and 750 ° C. or higher in order to exert the stress relieving function within the range in which the characteristics of each layer on the substrate are not deteriorated or largely deformed.
It is preferably in the range of ℃ or less.

Next, in the step shown in FIG. 11C, p-type I
nGaAlN layer 2, InGaAlN active layer 3 and n-type I
By etching each part of the nGaAlN layer 4, n-type In
A portion of the GaAlN layer 4 which will be a contact region for the n-side ohmic electrode is exposed, and p-type In
The p-type InGaAlN layer 2 is patterned so that the portion of the GaAlN layer 2 that will be the contact region for the p-side ohmic electrode is projected more than the other portions.

Next, in the step shown in FIG. 11D, on the substrate
For example, after depositing the Ni / Au film, the Ni / Au film is deposited.
By patterning, the p-type InGaAlN layer 2 is projected.
On the p-side ohmic electrode of the semiconductor laser
Form 15. Then, N ₂ Or O₂ In the atmosphere
By performing heat treatment at a temperature of about 600 ° C., p
Side ohmic electrode 15 and p-type InGaAlN layer 2
Contact resistance is reduced. Furthermore, on the substrate, for example, T
Pattern the Ti / Al film after depositing the i / Al film
Exposed out of the n-type InGaAlN layer 4 of the semiconductor laser
The n-side ohmic electrode 17 is formed on the exposed portion.
It After that, use well-known and common techniques such as chip cleaving process.
Therefore, a semiconductor laser can be formed.

A light emitting diode can be formed by utilizing the p-type InGaAlN layer 2, the InGaAlN active layer 3 and the n-type InGaAlN layer 4 in the laminated portion 10 shown in FIG. 11 (d).

Therefore, in this embodiment, the resistance of the p-type InGaAlN layer 2 is reduced by laser irradiation, and the p-type InGaAlN layer 2 and the p-side ohmic electrode 15 are formed.
The contact resistance with can be reduced. p-type I
When reducing the resistance of the nGaAlN layer 2, the laminated portion 10 is adjusted by adjusting the energy and pulse width of the laser to be irradiated.
It is possible to avoid heating the layers therein to high temperatures. Therefore, it is possible to suppress the diffusion of the dopant in the stacked portion 10 and maintain the steepness of the dopant profile. Therefore, it is possible to realize a device having low power consumption and good characteristics (such as a light emitting diode having a good light emitting characteristic and a semiconductor laser having a low threshold current) by reducing the contact resistance with the ohmic electrode. Become.

(Ninth Embodiment) FIGS. 12A to 12D.
FIG. 9A is a cross-sectional view showing the method for manufacturing the semiconductor device using the nitride semiconductor according to the ninth embodiment of the present invention.

First, in the step shown in FIG. 12A, the composition is changed on the sapphire substrate 1 (wafer) whose main surface is the (0001) plane by, for example, metal organic chemical vapor deposition (MOCVD). (Al _x Ga _1-x ) _y In _1-y N (0 ≦ x ≦
1, 0 ≦ y ≦ 1) n-type InG having a thickness of about 3 μm
The aAlN layer 4 is formed. Here, the n-type InGaAlN layer 4 may be formed after forming a thin amorphous AlN buffer layer (or GaN buffer layer) with a thickness of about 50 nm at a low temperature of about 500 ° C., for example. Although not shown, the n-type InGaAlN layer 4 includes an n-type GaN layer or an n-type AlGaN cladding layer. Then, n
On the type InGaAlN layer 4, the composition is (Al _x Ga
An undoped InGaAlN active layer 3 represented by _1-x ) _y In _1-y N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) is formed.
The InGaAlN active layer 3 includes, for example, an InGaN quantum well structure, and in the case of a light emitting diode or a semiconductor laser, it is a region that emits blue or blue-violet light in response to current injection. Further subsequently, on the InGaAlN active layer 3, the composition is _{(Al x Ga 1-x)} y In 1-y N
Thickness represented by (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) about 0.5 μ
A p-type InGaAlN layer 2 of m is formed. p-type InGa
The AlN layer 2 includes a p-type AlGaN clad layer or a p-type GaN layer. From the above, p-type InGaAl
N layer 2, InGaAlN active layer 3 and n-type InGaAl
The laminated portion 10 including the N layer 4 is formed.

In the above process, Si is used when the n-type layer is formed.
However, Mg is added as a dopant in forming the p-type layer. In addition, hydrogen gas is used as a carrier gas when performing epitaxial growth by MOCVD. In the as-grown state, p-type InGaA
Mg is bonded to hydrogen atoms in the 1N layer 2 (not activated), and as a result, the p-type InGaAlN layer 2 has a high electric resistance.

Next, in the step shown in FIG. 12B, the p-type InGaAlN layer 2 is irradiated with a beam (light flux) of a KrF excimer laser (wavelength 248 nm) from above in a nitrogen atmosphere.

Here, the power density and pulse width of the laser are set so that the p-type InGaAlN layer 2 is decomposed or altered, and the irradiation of the first step and the second step shown in FIG. 2 in the first embodiment is performed. . Thereby, p-type InGa
The AlN layer 2 is heated by absorbing a laser, hydrogen in the layer is desorbed from the film, and the p-type InGaAlN layer 2 is also released.
Is decomposed or deteriorated, and low resistance Ga with a small N composition ratio is obtained.
The N layer 16 is formed. Further, a metallic Ga layer containing almost no N is thinly formed on the surface of the low-resistance GaN layer 16.

In this step, the laser beam (light flux)
Is irradiated so as to scan the inside of the wafer surface, and the entire wafer is reduced to 50% in order to reduce the stress in the film due to the difference in the coefficient of thermal expansion of each layer in the sapphire substrate 1 and the laminated portion 10.
It is heated to about 0 ° C. This heating temperature is 400 ° C. or higher and 750 ° C. or higher in order to exert the stress relieving function within the range in which the characteristics of each layer on the substrate are not deteriorated or largely deformed.
It is preferably in the range of ℃ or less.

Next, in the step shown in FIG.
The surface portion of the low resistance GaN layer 16 is etched using an acid such as HCl. That is, in the step shown in FIG.
The p-type InGaAlN layer 2 is decomposed or altered to have a low resistance Ga.
The metal Ga layer having a relatively high resistance formed when changing to the N layer 16 is removed. Low resistance GaN layer 16 after etching
The surface is still rough.

Next, in the step shown in FIG. 12D, the low resistance GaN layer 16, the InGaAlN active layer 3 and the n-type InG are formed.
By etching each part of aAlN4, n-type InGaA
A portion of the 1N layer 4 which becomes a contact region for the n-side ohmic electrode is exposed, and a portion of the low-resistance GaN layer 16 which becomes a contact region for the p-side ohmic electrode is made to have a low resistance G so as to protrude more than other portions.
The aN layer 16 is patterned. After that, a semiconductor laser or a light emitting diode can be formed by using a well-known and commonly used technique.

FIG. 13 is a sectional view showing the structure of a semiconductor laser formed by the manufacturing process of the ninth embodiment. This structure is formed by the following process.

After the step shown in FIG. 12D, a Ni / Au film, for example, is deposited on the substrate, and then the Ni / Au film is patterned to form an upper portion of the low resistance GaN layer 16. And the p-side ohmic electrode 15 of the semiconductor laser
To form. Then, 60 in N ₂ or O ₂ atmosphere
By performing heat treatment at a temperature of about 0 ° C., the contact resistance between the p-side ohmic electrode 15 and the low resistance GaN layer 16 is reduced. In particular, the presence of surface roughness in the low-resistance GaN layer 16 increases the contact area between the low-resistance GaN layer 16 and the p-side ohmic electrode 15, so that the contact resistance reducing effect becomes remarkable.

Further, after depositing, for example, a Ti / Al film on the substrate, the Ti / Al film is patterned to form an n-type In film.
The n-side ohmic electrode 17 of the semiconductor laser is formed on the exposed portion of the GaAlN layer 4. afterwards,
The semiconductor laser can be formed by using a well-known and commonly used technique such as a chip cleaving process.

The low resistance GaN layer 16 shown in FIG.
A light emitting diode may be formed using the InGaAlN active layer 3 and the n-type InGaAlN layer 4.

Therefore, in this embodiment, since the p-type InGaAlN layer 2 is decomposed or altered by laser irradiation to form the low resistance GaN layer 16, the contact resistance with the ohmic electrode 15 can be reduced. it can.

The reason why the contact resistance between the low-resistance GaN layer 16 formed by decomposition or alteration of the p-type InGaAlN layer 2 and the ohmic electrode is small has not yet been clearly understood. However, the effect of reducing the contact resistance can be estimated as follows. First,
As described above, it is considered that the surface area of the low resistance GaN layer 16 increases the contact area with the ohmic electrode. Secondly, it is considered that the band gap (band gap) becomes smaller due to the composition of the GaN layer deviating from the stoichiometric composition, and the resistance in ohmic contact with the electrode as a conductor becomes smaller.

Therefore, it is possible to realize a device with low power consumption by reducing the contact resistance with the ohmic electrode (such as a light emitting diode having a good light emitting characteristic or a semiconductor laser having a low threshold current).

(Tenth Embodiment) FIG. 14A to FIG.
(D) is sectional drawing which shows the manufacturing method of the semiconductor device using the nitride semiconductor in the 10th Embodiment of this invention.

First, in the step shown in FIG. 14A, the composition is changed on the sapphire substrate 1 (wafer) whose main surface is the (0001) plane by, for example, metal organic chemical vapor deposition (MOCVD). (Al _x Ga _1-x ) _y In _1-y N (0 ≦ x ≦
1, 0 ≦ y ≦ 1) p-type InG having a thickness of about 3 μm
The aAlN layer 2 is formed. Here, the p-type InGaAlN layer 2 may be formed after forming a thin amorphous AlN buffer layer (or GaN buffer layer) of about 50 nm at a low temperature of about 500 ° C., for example. Although not shown, the p-type InGaAlN layer 2 includes a p-type GaN layer or a p-type AlGaN cladding layer. continue,
On the p-type InGaAlN layer 2, the composition is (Al _x Ga
An undoped InGaAlN active layer 3 represented by _1-x ) _y In _1-y N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) is formed.
The InGaAlN active layer 3 includes, for example, an InGaN quantum well structure, and in the case of a light emitting diode or a semiconductor laser, it is a region that emits blue or blue-violet light in response to current injection. Further subsequently, on the InGaAlN active layer 3, the composition is _{(Al x Ga 1-x)} y In 1-y N
Thickness represented by (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) about 0.5 μ
An n-type InGaAlN layer 4 of m is formed. n-type InGa
The AlN layer 4 includes an n-type AlGaN cladding layer or an n-type GaN layer. From the above, p-type InGaAl
N layer 2, InGaAlN active layer 3 and n-type InGaAl
The laminated portion 10 including the N layer 4 is formed.

In the above process, when forming the n-type layer, S
i and Mg are added as dopants when the p-type layer is formed. In addition, hydrogen gas is used as a carrier gas when performing epitaxial growth by MOCVD. In the as-grown state, p-type InGa
Mg is bonded to hydrogen atoms in the AlN layer 2,
Since the p-type impurities in the p-type InGaAlN layer 2 are not activated, the p-type InGaAlN layer 2 has a high electric resistance.

Next, in the step shown in FIG. 14B, a KrF excimer laser beam (wavelength 248 nm) is emitted from the back surface of the sapphire substrate 1 in a nitrogen atmosphere.

Here, the laser power density and pulse width are set such that the p-type InGaAlN layer 2 is decomposed.
The first stage irradiation and the second stage irradiation shown in FIG. As a result, the p-type InGaAlN layer 2 is heated by absorbing the laser, hydrogen in the same layer is desorbed from the film, and the p-type InGaAlN layer 2 is decomposed or deteriorated to have a low N composition ratio. Resistive GaN layer 16
Is formed. Further, a metallic Ga layer containing almost no N is thinly formed on the surface of the low-resistance GaN layer 16.

In this step, the laser beam (light flux)
Is irradiated so as to scan the inside of the wafer surface, and the entire wafer is reduced to 50% in order to reduce the stress in the film due to the difference in the coefficient of thermal expansion of each layer in the sapphire substrate 1 and the laminated portion 10.
It is heated to about 0 ° C. This heating temperature is 400 ° C. or higher and 750 ° C. or higher in order to exert the stress relieving function within the range in which the characteristics of each layer on the substrate are not deteriorated or largely deformed.
It is preferably in the range of ℃ or less.

Then, in the step shown in FIG. 14C, the laminated portion 10 (low-resistance GaN layer 16, InGaAlN active layer 3) is formed.
Then, the sapphire substrate 1 is separated from the n-type InGaAlN layer 4) (substrate separation). After that, the surface portion of the low-resistance GaN layer 16 is etched using an acid such as HCl. That is, in the step shown in FIG. 14B, the metal Ga layer formed when the p-type InGaAlN layer 2 is decomposed or altered and changed into the low resistance GaN layer 16 is removed. Surface roughness remains on the low-resistance GaN layer 16 after etching.

Next, in the step shown in FIG. 14D, after depositing, for example, a Ni / Au film on the low resistance GaN layer 16, the Ni / Au film is patterned to form a p-side ohmic contact of the light emitting diode. The electrode 15 is formed. Then, a heat treatment is performed at a temperature of about 600 ° C. in an N ₂ or O ₂ atmosphere, so that the p-side ohmic electrode 15 and the low resistance G are formed.
The contact resistance with the aN layer 16 is reduced. In particular, due to the presence of surface roughness in the low resistance GaN layer 16,
Since the contact area between the low-resistance GaN layer 16 and the p-side ohmic electrode 15 increases, the effect of reducing the contact resistance becomes remarkable.

Further, for example, a Ti / Al film is deposited on the lower surface of the n-type InGaAlN layer 4 to form the n-side ohmic electrode 17 of the light emitting diode.

Therefore, also in this embodiment, as in the ninth embodiment, the p-type InGaA is irradiated by the laser irradiation.
Since the low-resistance GaN layer 16 is formed by decomposing or degrading the 1N layer 2, the same operation as in the ninth embodiment is performed.
It is possible to reduce the contact resistance with the p-side ohmic electrode 15. Therefore, devices with low power consumption due to reduced contact resistance with ohmic electrodes (such as light emitting diodes and semiconductor lasers with low threshold current)
Can be realized.

(Other Embodiments) In each of the above embodiments, the sapphire substrate was used as the single crystal substrate, but the single crystal substrate in the present invention is not limited to this, and a SiC substrate, MgO as the single crystal substrate is used. Substrate, LiG
An aO ₂ substrate, a LiGa _x Al _1-x O ₂ (0 ≦ x ≦ 1) mixed crystal substrate, a LiAlO ₂ substrate, or the like can be used.

As the transfer substrate, a GaAs substrate, a GaP substrate, an InP substrate or the like can be used in addition to the Si substrate.

[0189]

According to the method for manufacturing a semiconductor device of the present invention, after a laminated film having first and second semiconductor layers made of a III-V group compound containing nitrogen is formed on a single crystal substrate,
By irradiating the p-type semiconductor layer in the laminated film with light, an activation treatment for desorbing hydrogen atoms from the p-type layer is performed, so that the steepness of the impurity concentration profile in the laminated film is maintained. , It is possible to reduce the resistance of the p-type layer,
It is possible to improve the characteristics of the semiconductor device formed using the stacked film.

[Brief description of drawings]

1A to 1C are cross-sectional views showing a method for manufacturing a semiconductor device using a nitride semiconductor according to a first embodiment of the present invention.

FIG. 2 shows the Kr irradiated in the first embodiment of the present invention.
It is a figure which shows the time change of the output of an F excimer laser.

3A to 3D are cross-sectional views showing a method for manufacturing a semiconductor device using a nitride semiconductor according to a second embodiment of the present invention.

4A to 4C are cross-sectional views showing a method for manufacturing a semiconductor device using a nitride semiconductor according to a third embodiment of the present invention.

5A to 5F are sectional views showing a method for manufacturing a semiconductor device using a nitride semiconductor according to a fourth embodiment of the present invention.

6A to 6C are cross-sectional views showing a method for manufacturing a semiconductor device using a nitride semiconductor according to a fifth embodiment of the present invention.

7A to 7C are cross-sectional views showing a method for manufacturing a semiconductor device using a nitride semiconductor according to a sixth embodiment of the present invention.

8A to 8D are cross-sectional views showing a method for manufacturing a semiconductor device using a nitride semiconductor according to a seventh embodiment of the present invention.

FIG. 9 is a cross-sectional view showing the structure of a heterojunction bipolar transistor formed by the manufacturing process of the seventh embodiment.

10A to 10C are configuration diagrams showing a conventional method for manufacturing a semiconductor device using a nitride semiconductor.

11A to 11D are cross-sectional views showing a method for manufacturing a semiconductor device using a nitride semiconductor according to an eighth embodiment of the present invention.

12A to 12D are cross-sectional views showing a method for manufacturing a semiconductor device using a nitride semiconductor according to a ninth embodiment of the present invention.

FIG. 13 is a cross-sectional view showing the structure of a semiconductor laser formed by the manufacturing process of the ninth embodiment.

14A to 14D are cross-sectional views showing a method for manufacturing a semiconductor device using a nitride semiconductor according to a tenth embodiment of the present invention.

[Explanation of symbols]

1 Sapphire substrate 2 p-type InGaAlN layer 3 InGaAlN active layer 4 n-type InGaAlN layer 5 Si substrate 6 oxide film cap layer 7 n-type Al _0.1 Ga _0.9 N layer 8 p-type GaN layer 9 n-type GaN layer 10 laminated portion 11 laminated portion 13 ZnO layer 15 p-side ohmic electrode 16 low resistance GaN layer 17 n-side ohmic electrode 21 collector electrode 22 base electrode 23 emitter layer 24 emitter electrode

Claims (32)

[Claims] 1. A method of manufacturing a semiconductor device having a semiconductor layer formed by epitaxial growth from a single crystal substrate, comprising III-V containing nitrogen doped with p-type impurities so as to cover the single crystal substrate. Forming a laminated film having at least a first semiconductor layer made of a group compound and an n-type second semiconductor layer made of a III-V group compound containing nitrogen doped with an n-type impurity; A step (b) of irradiating the first semiconductor layer with light to activate the p-type impurities in the first semiconductor layer. 2. The method of manufacturing a semiconductor device according to claim 1, wherein the light has an energy larger than at least a forbidden band width of at least a lowermost portion of the first semiconductor layer. Method. 3. The method for manufacturing a semiconductor device according to claim 1 or 2, wherein in the step (a), the first semiconductor layer is formed below the second semiconductor layer. In (b), the method of manufacturing a semiconductor device, wherein the first semiconductor layer is irradiated with the light from the back surface of the single crystal substrate. 4. The method for manufacturing a semiconductor device according to claim 3, wherein in the step (b), the power density or energy of the irradiated light is changed to at least two types,
A method of manufacturing a semiconductor device, which comprises activating p-type impurities in the first semiconductor layer and separating the first semiconductor layer and the single crystal substrate from each other. 5. The method of manufacturing a semiconductor device according to claim 3, further comprising a step of fixing a transfer substrate to the stacked body. 6. The method of manufacturing a semiconductor device according to claim 3, wherein in the step (b), after performing a first-stage treatment for activating the p-type impurity in the first semiconductor layer. ,
Second for separating the first semiconductor layer and the single crystal substrate from each other by changing the power density or energy of light
A method of manufacturing a semiconductor device, which comprises performing a stepwise process. 7. The method for manufacturing a semiconductor device according to claim 6, wherein after the treatment of the first step in the step (b) and before the treatment of the second step, the transfer is performed on the laminate. A method of manufacturing a semiconductor device, further comprising the step of fixing a substrate. 8. The method of manufacturing a semiconductor device according to claim 3, wherein in the step (b), the first semiconductor layer is decomposed or altered to form a conductor layer, and after the step (b), A method of manufacturing a semiconductor device, further comprising the step of forming an ohmic electrode made of a conductive material on the conductive layer. 9. The method of manufacturing a semiconductor device according to claim 8, further comprising a step of etching a surface portion of the conductor layer after the step (b) and before forming the ohmic electrode. And a method for manufacturing a semiconductor device. 10. The method for manufacturing a semiconductor device according to claim 3, wherein before the step (a), a spacer layer having a band gap smaller than that of the single crystal substrate is provided on the single crystal substrate. The method further includes a step of forming the laminated film on the spacer layer in the step (a), and activates the p-type impurity in the first semiconductor layer in the step (b). A method for manufacturing a semiconductor device, wherein the spacer layer and the single crystal substrate are separated from each other. 11. The method of manufacturing a semiconductor device according to claim 1, wherein in the step (a), the first semiconductor layer is formed above the second semiconductor layer, and In (b), the method for manufacturing a semiconductor device is characterized in that the first semiconductor layer is irradiated with the light from above the first semiconductor layer. 12. The method of manufacturing a semiconductor device according to claim 11, further comprising a step of forming a cap layer on the laminated portion after the step (a), and in the step (b), the cap is formed. A method of manufacturing a semiconductor device, characterized in that the first semiconductor layer is irradiated with light from above the layer. 13. The method of manufacturing a semiconductor device according to claim 12, wherein after the step (b), the step of removing the cap layer, the step of fixing the transfer substrate on the laminated portion, After or before fixing the transfer substrate, the step of irradiating light from the back surface of the single crystal substrate to separate the single crystal substrate from the laminated portion is further included. Production method. 14. The method of manufacturing a semiconductor device according to claim 13, wherein the energy of light emitted from the back surface of the substrate is larger than the light emitted from above the laminated portion in the step (b). A method for manufacturing a semiconductor device, comprising: 15. The method of manufacturing a semiconductor device according to claim 11, further comprising a step of forming an ohmic electrode made of a conductive material on the first semiconductor layer after the step (b). A method for manufacturing a characteristic semiconductor device. 16. The method of manufacturing a semiconductor device according to claim 11, wherein in the step (b), the first semiconductor layer is decomposed or altered to form a conductor layer, and after the step (b), A method of manufacturing a semiconductor device, further comprising the step of forming an ohmic electrode made of a conductive material on the conductive layer. 17. The method of manufacturing a semiconductor device according to claim 16, further comprising a step of etching a surface portion of the conductor layer after the step (b) and before forming the ohmic electrode. And a method for manufacturing a semiconductor device. 18. The method for manufacturing a semiconductor device according to claim 1, wherein in the step (a), the first semiconductor layer is sandwiched and the second semiconductor layer is opposed to the second semiconductor layer. A method of manufacturing a semiconductor device, further comprising: forming the laminated portion so as to further include an n-type third semiconductor layer having a bandgap different from that of the first semiconductor layer. 19. The method for manufacturing a semiconductor device according to claim 18, wherein the band gap of the third semiconductor layer is larger than that of the first semiconductor layer and larger than the energy of light. And a method for manufacturing a semiconductor device. 20. The method of manufacturing a semiconductor device according to claim 18, wherein a collector region of the bipolar transistor is formed from the first semiconductor layer, and a base region of the bipolar transistor is formed from the second semiconductor layer. A method for manufacturing a semiconductor device, comprising forming an emitter region of a bipolar transistor from the third semiconductor layer. 21. The method of manufacturing a semiconductor device according to claim 20, wherein the forbidden band width of the emitter region is larger than the forbidden band width of the base region. 22. The method of manufacturing a semiconductor device according to claim 1, wherein the step (c) is performed in an inert gas atmosphere or a reduced pressure atmosphere. Device manufacturing method. 23. The method of manufacturing a semiconductor device according to claim 1, wherein when the light activates a p-type impurity in the first semiconductor layer, A method of manufacturing a semiconductor device, wherein a material having energy smaller than the forbidden band width of the second semiconductor layer is used. 24. The method of manufacturing a semiconductor device according to claim 1, wherein the light source of the light is a laser that oscillates in a pulse shape. . 25. The method of manufacturing a semiconductor device according to claim 1, wherein the light activates a p-type impurity in the first semiconductor layer, and the light is a mercury lamp. The method for manufacturing a semiconductor device is characterized in that the bright line of the above is used. 26. The method of manufacturing a semiconductor device according to claim 1, wherein the single crystal substrate is heated when the light is irradiated. 27. The method of manufacturing a semiconductor device according to claim 26, wherein the heating temperature for heating the single crystal substrate is 400 ° C. or higher and 750 ° C. or lower. Manufacturing method. 28. The method of manufacturing a semiconductor device according to claim 1, wherein the light is applied so as to scan the light flux within a plane of the single crystal substrate. Manufacturing method of semiconductor device. 29. The method of manufacturing a semiconductor device according to claim 1, wherein in the step (a), Mg or Be is used as a dopant when forming the first semiconductor layer. A method for manufacturing a semiconductor device, comprising: 30. The method of manufacturing a semiconductor device according to claim 1, wherein in the step (a), the first semiconductor layer is formed in an atmosphere containing hydrogen. And a method for manufacturing a semiconductor. 31. The method of manufacturing a semiconductor device according to claim 1, wherein the single crystal substrate is a sapphire substrate, a SiC substrate,
MgO substrate, LiGaO ₂ substrate, LiGa _x Al _1-x O
_{2. A} method of manufacturing a semiconductor device, wherein one substrate selected from a ₂ (0 ≦ x ≦ 1) mixed crystal substrate and a LiAlO ₂ substrate is used. 32. The method according to claim 5, 6, 8, 9, 13 or 14.
In the method for manufacturing a semiconductor device described above, as the transfer substrate, a Si substrate, a GaAs substrate, a Ga substrate
A method of manufacturing a semiconductor device, wherein one substrate selected from a P substrate and an InP substrate is used.