JP2000286446A - Nitride semiconductor device and manufacture of the same, and gan substrate and manufacture of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nitride semiconductor device which provides good manufacturing yield while being superior in high volume productivity. SOLUTION: Related to a nitride semiconductor device comprising a nitride luminous element layer 9 on a GaN substrate 1, the GaN substrate 1 is doped with Mg, whose doping amount is 1×1017-1×1020 cm-3, with the thickness of the GaN substrate 1 being 100 μm or larger.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nitride semiconductor device such as a semiconductor laser or a light emitting diode having a nitride semiconductor layer and a method of manufacturing the same, and a GaN substrate used for the nitride semiconductor device and a method of manufacturing the same. About the method.

[0002]

2. Description of the Related Art In recent years, research and development of nitride-based semiconductor devices such as semiconductor lasers and light-emitting diodes made of nitride-based semiconductor layers such as GaN have been conducted.

[0003] For example, as a nitride semiconductor laser which is effective as a light source for recording or reproduction used in a high-density and large-capacity optical disk system, for example, "Jp
n. J. Appl. Phys. Vol. 38 (199
9) Pt. 2, No. 2B ", pp. 184-186. The nitride-based semiconductor laser disclosed in this document has an AlGa on a 100 μm-thick n-type GaN substrate doped with Si in a range of 10 ¹⁷ to 10 ¹⁸ cm ^−3.
This is a configuration in which a light-emitting element layer made of a nitride-based semiconductor layer such as N, GaN, or InGaN is formed.

[0004] However, such a semiconductor laser in which a light emitting element layer is formed on a GaN substrate has a problem that a large number of cracks occur in the wafer when a wafer of the GaN substrate is formed.

[0005] In addition, a wafer of a GaN substrate is used as shown in FIG.
As shown by arrow A in FIG. 7, when cleaving each light emitting element chip along the (10-10) plane, it does not cleave as such, and as shown by arrow B in FIG. There is a problem that the light emitting element is cleaved so as to be divided. This is
The GaN wafer is easily cleaved in the direction along the (10-10) plane.
This is because it exists in a direction shifted by 0 °.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks of the conventional example, and a nitride-based semiconductor device having a configuration in which cracks and the like are prevented from being generated in a GaN substrate during manufacturing, and a nitride semiconductor device having the same. It is an object of the present invention to provide a manufacturing method, and further provide a GaN substrate in which cracks and the like are unlikely to occur during the manufacturing and a manufacturing method thereof.

[0007]

The nitride-based semiconductor device of the present invention has a nitride-based semiconductor device layer on a GaN substrate, wherein the GaN substrate is doped with a p-type dopant. Doping amount is 1 × 10 ¹⁷
cm ^-3 or more and 1 × 10 ²⁰ cm ^-3 or less, and the GaN substrate has a thickness of 100 μm or more.

In the nitride-based semiconductor device having such a configuration, when a GaN substrate wafer is formed, generation of a large number of cracks in the wafer can be suppressed.

In particular, when the thickness of the GaN substrate is 100 or more and 500 μm or less, generation of a large number of cracks in the wafer can be suppressed, and the device is suitable for thinning the device.

Further, when the thickness of the GaN substrate is 100 or more and 300 μm or less, the wafer of the GaN substrate can be cleaved satisfactorily for each element.

Further, when the thickness of the GaN substrate is 100 or more and 200 μm or less, the wafer of the GaN substrate can be more efficiently cleaved for each element.

Further, as the p-type dopant, M
g is suitable.

Further, according to the method of manufacturing a nitride semiconductor device of the present invention, a first GaN layer is formed on a sapphire substrate,
A first step of re-growing a second GaN layer on the first GaN layer; and a sapphire substrate, the first GaN layer, and the second GaN layer from a back side of the sapphire substrate.
A part of the layer is removed to form a second GaN layer having a thickness of 100 μm or more.
A second step of forming a GaN wafer composed of layers, a third step of forming a nitride-based semiconductor layer on the GaN wafer, and a fourth step of cleaving the GaN wafer for each semiconductor chip. It is characterized by having.

In such a manufacturing method, generation of a large number of cracks in the GaN wafer during the second step is suppressed.

In particular, the GaN formed in the second step
When the thickness of the wafer is 100 μm or more and 500 μm or less, generation of a large number of cracks in the GaN wafer is suppressed, and a GaN wafer suitable for thinning semiconductor elements is produced.

Further, the GaN formed in the second step
When the thickness of the wafer is 100 μm or more and 300 μm or less, the fourth step can be performed favorably.

Further, the GaN formed in the second step
When the thickness of the wafer is 100 μm or more and 200 μm or less, the fourth step can be performed more favorably.

The p-type dopant may be M
g is suitable.

The GaN substrate of the present invention is doped with a p-type dopant, and the doping amount is 1
It is characterized by being in the range of not less than × 10 ¹⁷ cm ^{-3 and not} more than 1 × 10 ²⁰ cm ^-3 and having a thickness of not less than 100 μm.

In the GaN substrate having such a configuration, GaN
When a substrate wafer is formed, generation of a large number of cracks in the wafer is suppressed.

In particular, when the thickness of the GaN substrate is 100 μm or more and 500 μm or less, generation of a large number of cracks in the wafer can be suppressed, and it is suitable for thinning a semiconductor device using the GaN substrate.

Further, the GaN substrate has a thickness of 100 μm.
As described above, when the thickness is 300 μm or less, cleavage can be favorably performed on a GaN substrate wafer.

Further, the GaN substrate has a thickness of 100 μm.
As described above, when the thickness is 200 μm or less, cleavage can be performed more favorably on a GaN substrate wafer.

Further, as the p-type dopant, M
g is suitable.

Also, the method for manufacturing a GaN substrate includes a first step of forming a first GaN layer on a sapphire substrate and regrowing a second GaN layer on the first GaN layer; A part of the sapphire substrate, the first GaN layer, and the second GaN layer is removed from the back side of the substrate, and a Ga layer comprising a second GaN layer having a thickness of 100 μm or more is formed.
And a second step of forming an N wafer.

In such a manufacturing method, generation of a large number of cracks in the GaN wafer during the second step is suppressed.

In particular, the GaN formed in the second step
When the thickness of the wafer is 100 μm or more and 500 μm or less, generation of a large number of cracks in the GaN wafer is suppressed, and a GaN wafer suitable for thinning a semiconductor device using a GaN substrate is produced.

Further, the GaN formed in the second step
When the thickness of the wafer is 100 μm or more and 300 μm or less, the cleavage of the GaN wafer can be performed favorably.

Further, the GaN formed in the second step
When the thickness of the wafer is 100 μm or more and 200 μm or less, the cleavage of the GaN wafer can be performed more favorably.

Further, as the p-type dopant, M
g is suitable.

[0031]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view showing the structure of a semiconductor laser according to an embodiment of the present invention.

This semiconductor laser has a p-type GaN substrate 1
Buffer layer 2 made of p-type GaN, first clad layer 3 made of p-type AlGaN, n-type AlGa
A current blocking layer 4 composed of N, a second cladding layer 5 composed of p-type AlGaN, an active layer 6 having a multiple quantum well structure composed of InGaN, a third cladding layer 7 composed of n-type AlGaN, and n-type GaN. A light emitting element layer 9 composed of a contact layer 8 is formed. Ga
On the lower surface of the N substrate 1, a p-type electrode 10 is formed, and on the upper surface of the contact layer 8, an n-type electrode 11 is formed.

The GaN substrate 1 has a predetermined thickness d described later, and is doped with a predetermined amount of Mg described later.

Next, a method of manufacturing a GaN substrate and a method of manufacturing a semiconductor laser used in the semiconductor laser of the first embodiment will be described.

First, an AlGaN buffer layer 22 is grown on a sapphire substrate 21 as shown in FIG.
A first GaN layer 23 is grown thereon, and a SiO ₂ film 24 on a stripe is further formed thereon.

Next, as shown in FIG. 2B, the Mn is deposited on the GaN layer 23 exposed between the stripe-shaped SiO ₂ films 24.
The second GaN layer 25 doped with a predetermined amount of g is regrown.

When the second GaN layer 25 is further grown,
As shown in FIG. 2C, the second GaN layer 25 also grows in the lateral direction, and the second GaN layer 25 is formed on the SiO ₂ film 24 as well.

When the second GaN layer 25 is further grown,
As shown in FIG. 2D, the SiO ₂ film 24 and Si
A _second GaN layer 25 having a flat upper surface is formed on the first GaN layer 23 between the O ₂ films 24.

Next, from the sapphire substrate 21 side, FIG.
Polishing is performed up to the dashed line aa ′ in (d), and the sapphire substrate 21, the AlGaN buffer layer 22, the first GaN layer 23,
The SiO ₂ film 24 and a part of the second GaN layer 25 are removed. As a result, the second GaN layer 25 having a predetermined thickness d remains, and the second GaN layer 25 is formed on the GaN wafer 26 having the thickness d.
Becomes

Next, as shown in FIG. 3A, a nitride-based semiconductor layer 27 for forming a large number of the light emitting element layers 9 of FIG. 1 is formed on the upper surface of the GaN wafer 26. A large number of p-type electrodes 10 are formed on the lower surface of
A large number of n-type electrodes 11 are formed on the upper surface of.

Next, as shown in FIG. 3B, a kerf 28 is formed between the individual p-type electrodes 10 on the lower surface of the GaN wafer 26 in the direction along the (10-10) plane by diamond points or the like. Form.

Next, as shown by the arrow a, the GaN wafer 2
The GaN wafer 26 is cleaved into a plurality of elongated small wafers 29 by applying pressure along the cut grooves 28 from the upper surface side of 6, and further, the small wafer 29 is cleaved for each chip of each semiconductor laser.

Through the above steps, a semiconductor laser is formed.

FIG. 4 shows that the doping amount of Mg in the GaN substrate 1, that is, the doping amount of Mg in the second GaN layer 25 is 1
Steps shown in FIGS. 2D to 2E are performed on three patterns in the case of × 10 ¹⁸ cm ⁻³ , 1 × 10 ²⁰ cm ^−3, and 1 × 10 ²² cm ⁻³ . In the above, the thickness d of the GaN wafer 26 to be formed is changed from 50 μm to 500
The figure shows the substrate separation yield when changing in the range of μm. Note that the substrate separation yield is a ratio at which the GaN wafer 26 is favorably formed in the steps of FIGS. 2D to 2E.
However, those which were broken into four or more pieces were judged to be defective.

As can be seen from FIG. 4, the doping amount of Mg
Is 1 × 10¹⁸cm^-3Or 1 × 10 ²⁰cm^-3In the case of G
When the thickness of the aN wafer 26 becomes 100 μm or more, the substrate
The separation yield is 50% or more.

FIG. 5 shows the thickness d of the GaN substrate 1, that is, Ga
The graph shows the substrate separation yield when the thickness d of the N wafer 26 is 110 μm and the Mg doping amount of the GaN substrate 1, that is, the Mg doping amount of the GaN layer 25 is changed.

As can be seen from FIG. 5, when the thickness d of the GaN substrate 1, that is, the thickness d of the GaN wafer 26 is 110 μm, the doping amount of Mg is 1 × 10 ¹⁷ cm ⁻³ or more.
In the range of 10 ²¹ cm ^-3 or less, the substrate separation yield is 50
% Or more.

That is, when the conductivity type of the GaN substrate 1 is p-type, the doping amount of the p-type dopant is set to 1 × 10 ¹⁷ cm ^−3.
The GaN substrate 1 is set to a range of 1 × 10 ²⁰ cm ⁻³ or less.
By setting the thickness of the GaN wafer to 100 μm or more, a GaN wafer for forming the GaN substrate 1 can be manufactured with high yield.

FIG. 6 shows that the doping amount of Mg in the GaN substrate 1, that is, the doping amount of Mg in the GaN layer 25 is 1 × 1.
When 0 ¹⁸ cm ^-3 and 1 × 10 ²⁰ cm ^-3 ,
For three patterns in the case of 1 × 10 ²² cm ⁻³ , the thickness d of the GaN wafer 26 is set to 50 μm to 500 μm.
The figure shows the substrate cleavage yield when changed in the range of m. In addition, the substrate cleavage yield is defined as shown in FIG.
In the step (c), when the wafer is broken in the direction indicated by the arrow A in FIG. 7A, it is determined that the wafer has been cleaved satisfactorily, and the wafer is not broken as shown in FIG. If the wafer was broken in the direction indicated by the arrow B in FIG. 7B, it was determined to be defective.

As can be seen from FIG. 6, the doping amount of Mg
Is 1 × 10¹⁸cm^-3Or 1 × 10 ²⁰cm^-3In the case of G
The thickness of the aN wafer 26 is 100 μm or more and 300 μm or less
In the lower range, the cleavage yield of the substrate is 50% or more.
Furthermore, the thickness of the GaN wafer 26 is 100 μm or more,
In the range of 200 μm or less, the cleavage yield of the substrate is 70%.
% Or more.

In the above embodiment, the case where the present invention is applied to a semiconductor laser has been described. However, the present invention is also applicable to a nitride-based light emitting diode and other nitride-based electronic devices. Applicable.

[0053]

According to the present invention, the production yield is good,
A nitride-based semiconductor device having a configuration excellent in mass productivity can be provided.

Further, according to the present invention, it is possible to provide a method of manufacturing a nitride-based semiconductor device capable of manufacturing a nitride-based semiconductor device with high yield without cracking or the like of the GaN substrate.

Further, according to the present invention, it is possible to provide a GaN substrate having a configuration in which cracks and the like hardly occur during manufacturing.

Further, according to the present invention, it is possible to provide a method of manufacturing a GaN substrate capable of manufacturing a GaN substrate with good yield without cracking or the like.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of a semiconductor laser of the present invention.

FIG. 2 is a view illustrating a method of manufacturing a GaN substrate according to the present invention.

FIG. 3 is a diagram illustrating a method for manufacturing a semiconductor laser according to the present invention.

FIG. 4 is a diagram showing a change in a substrate separation yield depending on the thickness of a GaN wafer.

FIG. 5 is a diagram showing a change in a substrate separation yield depending on a doping amount of Mg.

FIG. 6 is a diagram showing a change in cleavage yield depending on the thickness of a GaN wafer.

FIG. 7 is a diagram showing a cleavage direction of a GaN wafer.

[Explanation of symbols]

 Reference Signs List 1 GaN substrate 9 light emitting element layer (semiconductor element layer) 21 sapphire substrate 23 first GaN layer 25 second GaN layer 26 GaN wafer 27 semiconductor layer

Claims (20)

[Claims] In a nitride semiconductor device having a nitride semiconductor device layer on a GaN substrate, the GaN substrate is doped with a p-type dopant, and the doping amount is 1 × 10 ¹⁷ cm ^−3. As described above, the nitride semiconductor device has a range of 1 × 10 ²⁰ cm ⁻³ or less, and the GaN substrate has a thickness of 100 μm or more. 2. The nitride-based semiconductor device according to claim 1, wherein said GaN substrate has a thickness of 100 μm or more and 500 μm or less. 3. The nitride-based semiconductor device according to claim 1, wherein the thickness of said GaN substrate is 100 μm or more and 300 μm or less. 4. The nitride-based semiconductor device according to claim 1, wherein said GaN substrate has a thickness of 100 μm or more and 200 μm or less. 5. The nitride-based semiconductor device according to claim 1, wherein said p-type dopant is Mg. 6. A first GaN layer is formed on a sapphire substrate, and a 1 × 1 p-type dopant is formed on the first GaN layer.
A first step of re-growing a second GaN layer doped in a range of 0 ¹⁷ cm ⁻³ or more and 1 × 10 ²⁰ cm ⁻³ or less, and the sapphire substrate from the back side of the sapphire substrate, A second step of forming a GaN wafer composed of a second GaN layer having a thickness of 100 μm or more by removing a part of the first GaN layer and a part of the second GaN layer;
A third step of forming a nitride-based semiconductor layer on the wafer, and a fourth step of separating the GaN wafer into individual semiconductor chips.
And a method for manufacturing a nitride-based semiconductor device. 7. The method according to claim 6, wherein the thickness of the GaN wafer formed in the second step is 100 μm or more and 500 μm or less. 8. The method according to claim 6, wherein the thickness of the GaN wafer formed in the second step is not less than 100 μm and not more than 300 μm. 9. The method according to claim 6, wherein the thickness of the GaN wafer formed in the second step is 100 μm or more and 200 μm or less. 10. The method for manufacturing a nitride-based semiconductor device according to claim 6, wherein said p-type dopant is Mg. 11. A p-type dopant is doped, and the doping amount is 1 × 10 ¹⁷ cm ⁻³ or more.
A GaN substrate having a thickness of 10 ²⁰ cm ⁻³ or less and a thickness of 100 μm or more. 12. The GaN substrate according to claim 11, wherein the thickness is 100 μm or more and 500 μm or less. 13. The GaN substrate according to claim 11, wherein the thickness is 100 μm or more and 300 μm or less. 14. The GaN substrate according to claim 11, wherein the thickness is 100 μm or more and 200 μm or less. 15. The GaN substrate according to claim 11, wherein said p-type dopant is Mg. 16. A first GaN layer is formed on a sapphire substrate, and a 1 × p-type dopant is formed on the first GaN layer.
A first step of re-growing a second GaN layer doped in a range of 10 ¹⁷ cm ⁻³ or more and 1 × 10 ²⁰ cm ⁻³ or less, and the sapphire substrate, Removing a part of the first GaN layer and a part of the second GaN layer to form a GaN wafer composed of a second GaN layer having a thickness of 100 μm or more. Production method. 17. The method according to claim 16, wherein the thickness of the GaN wafer formed in the second step is 100 to 500 μm. 18. The method according to claim 16, wherein the thickness of the GaN wafer formed in the second step is 100 to 300 μm. 19. The method according to claim 16, wherein the thickness of the GaN wafer formed in the second step is 100 to 200 μm. 20. The method of manufacturing a GaN substrate according to claim 16, wherein said p-type dopant is Mg.