JPH10107317A - Gan element substrate, its manufacturing method and gan element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve light-emitting efficiency and light-fetching efficiency by constituting a substrate using a single crystal layer, which is expressed as Alx Iny Ga(1-x-y) N (where, 0<=x<1, 0<=y<1, 0<= (x+y)<1) and is grown on a metal aluminum single crystal layer. SOLUTION: The surface of an Al single crystal thin film 7 is nitrided, an Si doped n type GaN layer 6 is grown, and an Si doped n type AlGaN layer 5 is grown. Then, a Zn-doped InGaN layer 4 is grown, then an Mg-doped p-type AlGaN layer 3 is grown again, and an Mg doped p-type GaN layer 2 is grown on the layer 3. At that time, the layer is a single crystal layer expressed as Alx Iny Ga(1-x-y) N (where, 0<=x<1, 0<=y<1, 0<=(x+y)<1). Thus, a high quality GaN crystal is grown, and since an Si substrate is used as a conductive substrate, n-type and p-type electrodes 1 and 9 can be provided on the Si substrate, and light-emitting efficiency and light-etching efficiency are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate for a GaN-based element used for a blue light emitting diode (LED) and a laser diode (LD), a method of manufacturing the same, and a GaN-based element.

[0002]

2. Description of the Related Art GaN-based compound semiconductors such as gallium nitride (GaN) and indium gallium nitride (InGa)
N), gallium aluminum nitride (GaAlN), etc.
Blue light emitting diode (LED) and laser diode (L
D) is in the limelight.

[0003] Further, since this GaN-based compound semiconductor has good heat resistance and environmental resistance, development for application to electronic device elements other than optical elements is also being conducted.

Meanwhile, GaN-based compound semiconductors are difficult to grow in bulk crystal, and a GaN substrate that can be put to practical use has not yet been obtained. At present, GaN widely used in practice
Sapphire is used for the growth substrate. Generally, a method of epitaxially growing GaN on a single crystal sapphire substrate by, for example, metal organic chemical vapor deposition (MOVPE) is used.

Since a sapphire substrate has a different lattice constant from GaN, a single crystal film cannot be grown by directly growing GaN on the sapphire substrate.

As a countermeasure for this, Japanese Patent Laid-Open No. 63-18 / 1988
No. 8983, a method of temporarily growing a buffer layer of AlN or GaN on a sapphire substrate at a low temperature, relaxing lattice distortion in the buffer layer, and then growing GaN on the buffer layer It has been known.

However, as described above, even in the method of relaxing the lattice distortion in the buffer layer grown at a low temperature, strictly speaking, the deviation of the lattice constant between the sapphire substrate and GaN is hardly at all, and the GaN has a defect. There is a case where a portion is generated and a GaN-based laser diode (LD) as a product is damaged.

Further, since the sapphire substrate is insulative, when manufacturing a GaN-based device, no electrode can be attached to the back surface of the substrate. For this reason, for example, in a blue LED, an electrode is provided by digging down from the GaN crystal surface to the GaN layer near the sapphire substrate.

However, it is necessary to provide two electrodes, a p-side electrode and an n-side electrode, on the surface side of the sapphire substrate, and it is difficult to secure an electrode area. In addition, a problem has been pointed out that two electrodes obstruct the position in extracting light.

Further, since the sapphire substrate has no cleavage property, it is difficult to form a GaN-based device into chips. When manufacturing a laser diode (LD), there are problems such as difficulty in manufacturing a resonator by cleavage.

In response to the above circumstances, gallium arsenide (GaAs) and silicon (S) are used instead of the sapphire substrate.
i), neodymium gallium trioxide NdGaO ₃ (NG
O) and other substrates are being considered.
A method is employed in which a buffer layer of AlN or GaN is grown at a low temperature, and GaN is grown thereon.

However, the problem of the lattice constant difference and the problem of controlling the crystal shape of the growing GaN still remain.
Not practical.

Next, a specific conventional example will be described.

On a 2 inch diameter sapphire c-plane substrate,
Undoped GaN by reduced pressure (0.1atm) MOVPE method
A crystal was grown. After setting the substrate temperature to 550 ° C,
Trimethyl aluminum (TMA) and ammonia (NH
₃ ) The AlN buffer layer is grown to a thickness of 500 angstroms using the raw material of ₃ ).

Thereafter, the substrate temperature is raised to 900 ° C.
Trimethylgallium (TMG) and ammonia (NH ₃ )
Was used as a raw material to grow a GaN layer by 2 μm.

In this conventional example, four crystals X
The half width of the line rocking curve is 350 arcsec, and the transition density in the GaN crystal by TEM observation is 8 arcsec.
１１11 × 10 ⁸ cm ⁻³ .

Further, another specific conventional example will be described below with reference to FIG.

GaN blue LE using sapphire substrate
In this example, the following crystal was grown on a 2 inch diameter sapphire c-plane substrate 11 by a reduced pressure (0.1 atm) MOVPE method.

The raw material is trimethylaluminum (TM
A), trimethyl gallium (TMG), trimethyl indium (TMI), and ammonia (NH ₃₎ is used.

The dopant is disilane (Si ₂ H ₆ ),
Diethyl zinc (DEZ) and biscyclopentadienyl magnesium (Cp ₂ Mg) are used.

The substrate temperature of the sapphire c-plane substrate 11 is 55
The temperature is set to 0 ° C., and the AlN buffer layer 10 is grown by 500 Å. Thereafter, the substrate temperature was raised to 1000 ° C., a 4 μm Si-doped n-type GaN layer 6 was grown, and the Si-doped n-type AlGaN
m.

Next, the substrate temperature is lowered to 700 ° C.
The n-doped InGaN layer 4 is grown to 500 Å, the substrate temperature is returned to 1000 ° C. again, the Mg-doped p-type AlGaN layer 3 is grown to 0.1 μm, and M
The g-doped p-type GaN layer 2 was grown to 0.2 μm.

In order to reduce the resistance of the p-layer having the above structure, a heat treatment is performed at 700 ° C. for 1 hour in a nitrogen atmosphere, and finally a GaN blue LED using a sapphire substrate as shown in FIG. Was produced.

In another conventional example, since an insulating sapphire is used for the substrate, an n-side electrode cannot be provided on the back surface of the substrate. For this reason, as shown in FIG.
Etching was performed until the n-type GaN layer 6 was exposed, and an n-side electrode 9 was formed on the exposed n-type GaN layer 6.

In another conventional example, a light emitting diode (L
In order to use ED) as a chip, if a kerf is formed from the back side of the substrate with a dicing saw and divided, cracks often occur in portions other than the kerf, and the chip yield was less than 40%.

When the obtained chip was mounted on a stem and energized, blue light emission having a light emission wavelength of 450 nm was observed. The emission output at this time was 1.5 mW when 20 mA was applied.

[0027]

SUMMARY OF THE INVENTION In view of the above-mentioned situation, the present invention makes it possible to grow a high-quality GaN-based crystal by making a substrate conductive, and in terms of the structure, n is formed on each of the back and front surfaces of the substrate. And p-type electrodes can be provided,
The area required for the arrangement of the electrodes and the light extraction are not hindered, the cleavability is excellent, and the GaN-based device can be easily formed into a chip. In particular, the GaN-based laser diode (LE)
In D), an object is to provide a GaN-based element substrate, a method of manufacturing the same, and a GaN-based element that can improve the light emission efficiency and light extraction efficiency.

[0028]

In order to achieve the above object, a substrate for a GaN-based device according to the present invention comprises: a silicon single crystal substrate; a metal aluminum single crystal layer deposited on the silicon single crystal substrate; Al _x In _y Ga _(1-xy) N grown on a metal aluminum single crystal layer (where 0 ≦ x
<1, 0 ≦ y <1, 0 ≦ (x + y) <1).

Further, in the method of manufacturing a substrate for a GaN-based element according to the present invention, a step of depositing a metal aluminum single crystal layer on a silicon single crystal substrate, and the step of depositing the deposited metal aluminum single crystal layer at 400 ° C. or more. Heating the metal aluminum single crystal layer within a temperature range in which the metal aluminum single crystal layer does not melt, and nitriding the surface of the metal aluminum single crystal layer after the heating step.

Further, the GaN-based device of the present invention comprises a silicon single crystal substrate, a metal aluminum single crystal layer deposited on the silicon single crystal substrate, and an Al _x In _y grown on the metal aluminum single crystal layer. A single crystal layer represented by Ga _(1-xy) N (0 ≦ x <1, 0 ≦ y <1, 0 ≦ (x + y) <1), the silicon single crystal substrate and the G
an electrode formed on the aN single crystal layer.

[0031]

Embodiments of the present invention will be described below in detail.

As a first embodiment, a metal Al film is formed on a 2 inch diameter Si {111} substrate by a vapor deposition apparatus.
Angstrom deposition and set in MOVPE apparatus. An undoped GaN crystal was grown on the metal Al film under a reduced pressure of 0.1 atm.

More specifically, after the Si substrate on which the metal Al film is deposited is kept at 500 ° C. for 5 minutes in a nitrogen atmosphere, ammonia (N
H ₃ ) was flowed, and the Al surface was nitrided for 10 minutes.

Thereafter, the substrate temperature was raised to 900 ° C., and trimethylgallium (TMG) and ammonia (N
A GaN layer was grown at 2 μm using H ₃ ) as a raw material.

In the above-described first embodiment of the present invention,
The half width of the four crystal X-ray rocking curve of the grown crystal is 120 arcsec, and Ga
The transition density in the N crystal was 4 to 6 × 10 ⁶ cm ^-3 .

As a second embodiment of the present invention, GaN
An example of manufacturing a GaN blue LED as a system element will be described with reference to FIG.

For comparison with the prior art, the same equipment, raw materials and dopants as those used in the other conventional examples are used, and the explanation is omitted.

The substrate 8 used is a 2 inch diameter Si.
It is a {111} substrate, p-doped n-type, and has a carrier concentration of 5 × 10 ¹⁸ cm ⁻³ .

The substrate is set in a MOVPE apparatus, the substrate temperature is maintained at 550 ° C., and only trimethyl aluminum (TMA) is supplied. For this reason, trimethyl aluminum (TMA) is thermally decomposed on the Si substrate 8 and Al
A single crystal thin film 7 grows.

When the Al single crystal thin film 7 has grown to a thickness of 400 Å, supply of trimethyl aluminum (TMA) is stopped, and then ammonia (NH ₃ )
Is supplied, and the surface of the Al single crystal thin film 7 is subjected to nitriding treatment for 10 minutes.

Thereafter, the substrate temperature is raised to 1000 ° C.
The Si-doped n-type GaN layer 6 was grown to 4 μm, and subsequently the Si-doped n-type AlGaN layer 5 was grown to 0.1 μm.

Next, the substrate temperature was lowered to 700 ° C.
The n-doped InGaN layer 4 is grown to 500 Å, the substrate temperature is returned to 1000 ° C. again, the Mg-doped p-type AlGaN layer 3 is grown to 0.1 μm, and M
The g-doped p-type GaN layer 2 was grown to 0.2 μm.

The p-side electrode 1 is provided on the Mg-doped p-type GaN layer 2, and the n-side electrode 9 is provided on the back surface of the Si substrate 8.

In order to lower the resistance of the p-layer having the above-described structure, a heat treatment is performed at 700 ° C. for 1 hour in a nitrogen atmosphere, and finally a G layer using a Si substrate as shown in FIG.
An aN-based device, for example, a GaN-based blue LED was manufactured.

When the chip obtained as described above was mounted on a system and energized, blue light emission with an emission wavelength of 450 nm was observed. The emission output at that time was 2.2 mW when 20 mA was applied.

According to the first and second embodiments described above,
Since a high-quality GaN-based crystal can be grown and a Si substrate is used as a conductive substrate, n-type and p-type electrodes can be provided on the back and front surfaces of the Si substrate, respectively. This does not hinder the required area and light extraction, and eliminates the need for conventional RIE-based etching of GaN-based crystals to provide electrodes in the manufacturing process.

Further, the photolithography process for forming the electrodes can be greatly simplified. Further, even if a dicing saw was used to cut a groove from the back side of the Si substrate and divided, there was no crack other than at the groove. For this reason, the yield of chips was as high as 90% or more.

According to the above-described first and second embodiments, the temperature for heating the metal Al film or the Al single crystal thin film is set at 500 ° C. or 550 ° C., but single-phase Al can be obtained. The temperature may be 400 ° C. or higher at which good crystallinity can be secured when GaN is grown thereon and within a temperature range at which the Al film does not melt.

Therefore, even if the melting point of Al is 660 ° C. or higher, heating may be performed at 800 ° C. if the solid phase reaction between Al and Si causes alloying and does not melt. As described above, the temperature at which the Al film does not melt is not specified because it is determined by the thickness of the Al film and the deposition conditions.

According to the first and second embodiments, the GaN layer is grown on the surface of the nitrided Al film. After growing the layer, a GaN layer may be grown thereon. With this buffer layer, lattice distortion can be reduced.

In the above embodiment of the manufacturing method, the step of nitriding the surface of the Al film is employed.
The reaction between Al and the N source flowing to grow GaN without intentionally nitriding the surface of the
Since the surface of the film may be naturally nitrided, the process can be omitted without forcibly performing the nitriding treatment.

In the above-described embodiment, a GaN-based device,
For example, a GaN-based blue LED has been described, but a GaN-based material such as a laser diode (LD) or a light-receiving element, an electronic device element utilizing the heat resistance, environmental resistance, and other physical properties of the GaN-based material, a SAW filter, or the like. It can be widely used for an element to be used.

[0053]

According to the above-described substrate for a GaN-based device, the method of manufacturing the same, and the GaN-based device of the present invention, the substrate is made of Si.
Since a semiconductor crystal is used, a back electrode that cannot be provided by a conventional sapphire substrate can be provided. This not only facilitates the manufacture of GaN-based devices, but also
More room for structural design. In addition, since the back electrode can be employed, a light extraction surface can be provided at a high efficiency when a GaN-based device is manufactured, and the luminance of the light-emitting device can be improved.

Since the crystallinity of the GaN crystal is improved and the defect density is reduced, the characteristics of the GaN-based device are improved. Light emitting diodes (LEDs) increase brightness, and laser diodes (LDs) increase life and reliability.

In the case of a sapphire substrate, machining of the substrate, which has been difficult, is facilitated, and the yield of device chips is improved. In particular, since it becomes possible to cleave a crystal, it becomes easy to form a resonator of a laser diode (LD).

Since the Si substrate is inexpensive as compared with the sapphire substrate, the manufacturing cost of the GaN-based device can be reduced in addition to the effect of simplifying the device manufacturing process.

Further, since all the materials and devices can be the same as those used in the conventional GaN-based crystal manufacturing process, the GaN-based crystal based on the high-quality GaN-based crystal has a high economic effect.
A substrate for a system element, a method for manufacturing the same, and a GaN element can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a GaN-based blue light emitting diode (LED) showing an embodiment of the present invention.

FIG. 2 shows a conventional GaN-based blue light emitting diode (LED)
FIG.

[Explanation of symbols]

 Reference Signs List 1 p-side electrode 2 p-type GaN layer 3 p-type AlGaN layer 4 InGaN layer 5 n-type AlGaN layer 6 n-type GaN layer 7 metal Al layer 8 silicon substrate 9 n-side electrode

Claims (14)

[Claims] 1. A silicon single crystal substrate, a metal aluminum single crystal layer deposited on the silicon single crystal substrate, and an Al _x In _y grown on the metal aluminum single crystal layer.
Ga _(1-xy) N (where 0 ≦ x <1, 0 ≦ y <1, 0 ≦
A single crystal layer represented by (x + y) <1)
Substrate for N-based devices. 2. A GaN-based element substrate comprising a silicon single crystal substrate and a metal aluminum single crystal whose surface is nitrided and deposited on the silicon single crystal substrate. 3. A silicon single crystal substrate; a metal aluminum single crystal deposited on the silicon single crystal substrate, the surface of which is nitrided; and Al _x In _y Ga _(1-xy) grown on the metal aluminum single crystal layer. ₎ N (where 0 ≦ x <1, 0 ≦ y
And a single crystal layer represented by <1,0 ≦ (x + y) <1) and a GaN-based element substrate. 4. The method according to claim 1, wherein the silicon single crystal substrate is Si ｛11.
4. The GaN-based element substrate according to claim 1, wherein the substrate is a 1 ° substrate. 5. A buffer comprising a silicon single crystal substrate, a metal aluminum single crystal deposited on the silicon single crystal substrate, the surface of which is nitrided, and an AlN or GaN grown on the surface of the metal aluminum single crystal at a low temperature. Layer and Al _x In _y Ga _(1-xy) N grown on the buffer layer
(However, 0 ≦ x <1, 0 ≦ y <1, 0 ≦ (x + y) <1)
And a single crystal layer represented by the following formula: 6. The silicon single crystal substrate is made of Si 単 11.
The Ga according to claim 5, wherein the Ga substrate is a 1｝ substrate.
Substrate for N-based devices. 7. A step of depositing a metal aluminum single crystal layer on a silicon single crystal substrate, and a temperature range in which the deposited metal aluminum single crystal layer is at 400 ° C. or higher and the metal aluminum single crystal layer is not melted. And a step of nitriding the surface of the metal aluminum single crystal layer after the heating step. 8. A step of depositing a metal aluminum single crystal layer on a silicon single crystal substrate, and a temperature range in which the deposited metal aluminum single crystal layer is heated to 400 ° C. or higher and the metal aluminum single crystal layer is not melted. Heating the metal aluminum single crystal layer after the heating step; and nitriding the surface of the metal aluminum single crystal layer after the heating step; and forming an Al _x In _y Ga on the surface of the nitrided metal aluminum single crystal layer.
_(1-xy) N (where 0 ≦ x <1, 0 ≦ y <1, 0 ≦ (x +
y) a step of growing a single crystal layer represented by <1), and a method of manufacturing a GaN-based element substrate. 9. A step of depositing a metal aluminum single crystal layer on a silicon single crystal substrate while heating the metal aluminum single crystal layer at a temperature of 400 ° C. or more and not melting the metal aluminum single crystal layer; Nitriding the surface of the metal aluminum single crystal layer; and forming Al _x In _y Ga on the surface of the nitrided metal aluminum single crystal layer.
_(1-xy) N (where 0 ≦ x <1, 0 ≦ y <1, 0 ≦ (x +
y) a step of growing a single crystal layer represented by <1), and a method of manufacturing a GaN-based element substrate. 10. A step of depositing a metal aluminum single crystal layer on a silicon single crystal substrate, and a temperature range in which the deposited metal aluminum single crystal layer is at least 400 ° C. and at which the metal aluminum single crystal layer does not melt. And heating the aluminum aluminum single crystal layer on the surface of the metal aluminum single crystal layer.
l _x In _y Ga _(1-xy) N (where 0 ≦ x <1, 0 ≦ y <
Growing a single crystal layer represented by 1,0 ≦ (x + y) <1), and a method for manufacturing a GaN-based element substrate. 11. The silicon single crystal substrate is made of Si ｛11
The method for manufacturing a GaN-based element substrate according to any one of claims 7 to 10, wherein the substrate is a 1｝ substrate. 12. A silicon single crystal substrate, a metal aluminum single crystal layer deposited on the silicon single crystal substrate,
Al _x In grown on the metal aluminum single crystal layer
_y Ga _(1-xy) N (where 0 ≦ x <1, 0 ≦ y <1, 0 ≦
A GaN-based device comprising: a single crystal layer represented by (x + y) <1); and electrodes respectively formed on the silicon single crystal substrate and the GaN single crystal layer. 13. A silicon single crystal substrate, a metal aluminum single crystal deposited on the silicon single crystal substrate, the surface of which is nitrided, and an Al _x In _y Ga _(1-xy) grown on the metal aluminum single crystal layer. ₎ N (where 0 ≦ x <1, 0 ≦
a single crystal layer represented by y <1, 0 ≦ (x + y) <1);
A GaN-based device comprising: the silicon single crystal substrate and electrodes formed on the GaN single crystal layer, respectively. 14. The silicon single crystal substrate is made of Si ｛11.
The GaN-based device according to claim 12, wherein the GaN-based device is a 1 ° substrate.