JP2002026438A - Nitride-based semiconductor element and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nitride-based semiconductor element which can improve the yield in a cleaving step and can be mass-produced and a method of manufacturing the element. SOLUTION: The semiconductor laser element 100 is constituted by successively laminating an n-buffer layer 2, n-clad layer 3, active layer 4, p-clad layer 5, and p-contact layer 6 on one surface of an n-GaN substrate 1 having a thickness of 120-200 μm. On a prescribed area of the contact layer 6, a p-electrode 15 is formed. The other surface of the substrate 1 is formed in an uneven surface containing recessed sections having depths of <=0.1% of the thickness of the substrate 1 and an n-electrode 16 is formed in the recessed sections and on the projecting sections of the surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a nitride semiconductor device using a nitride semiconductor substrate and a method of manufacturing the same. Here, BN (boron nitride), GaN
(Gallium nitride), AlN (aluminum nitride), In
N (indium nitride) or TlN (thallium nitride)
Alternatively, a group III-V nitride semiconductor such as a mixed crystal thereof is referred to as a nitride semiconductor.

[0002]

2. Description of the Related Art In a nitride-based semiconductor device having a nitride-based semiconductor layer formed on a sapphire substrate, the difference in lattice constant between the sapphire substrate and the nitride-based semiconductor layer is large. Therefore, many dislocations occur in the nitride-based semiconductor layer grown on the sapphire substrate, and the crystallinity is deteriorated. Therefore, in such a nitride-based semiconductor device, the device characteristics deteriorate.

Therefore, instead of a sapphire substrate, Ga
Research on a nitride semiconductor device using a substrate made of a nitride semiconductor such as N has been advanced.

FIG. 6 is a schematic sectional view showing an example of a semiconductor laser device in which a GaN-based semiconductor layer is formed on a GaN substrate.

The semiconductor laser device shown in FIG.
On an N substrate 50, an n-GaN layer 51 having a thickness of about 3 μm and an n-I layer made of n-In _0.05 Ga _0.95 N having a thickness of 1000 °
nGaN buffer layer 52, 4000 nm thick n-Al _0.05 G
a n-AlGaN cladding layer 53 made of a _0.95 N, n-GaN optical guiding layer 5 made of n-GaN having a thickness of 70 °
4. MQW active layer 55 having a multiple quantum well (MQW) structure, p-AlGaN layer 56 made of p-Al _0.2 Ga _0.8 N having a thickness of 2000 °, p-GaN layer 5 having a thickness of 70 °
7. A p-AlGaN cladding layer 58 made of p-Al _0.05 Ga _0.95 N having a thickness of 4000Å and a p-GaN light guide layer 59 made of p-GaN having a thickness of 4000Å are sequentially formed. An n-electrode 60 is formed on a surface (back surface) opposite to the crystal growth surface of n-GaN substrate 50. Also,
A p-electrode 61 is formed on a predetermined region of the p-GaN light guide layer 59.

In manufacturing the semiconductor laser device, first, the layers 51 to 59 are grown on an n-GaN substrate 50 having a thickness of about 300 to 500 μm. After that, the end face of the resonator is formed and the elements are separated by cleavage. Here, in this case, since GaN is a material having a very high hardness, it is very difficult to cleave the n-GaN substrate 50 having such a large thickness.

Therefore, in manufacturing a conventional semiconductor laser device, before the cleavage step, the n-GaN substrate 50 is polished (lapping) until the thickness of the n-GaN substrate 50 becomes about 100 μm. Thus, n-Ga
After the N substrate 50 is polished to reduce the thickness, the substrate is cleaved to form a resonator end face and perform element isolation.

[0008]

As described above, n-Ga
Since the N substrate 50 has a very high hardness, the thickness is set to 120 μm.
Even when the distance is about m, it is difficult to easily cleave the n-GaN substrate 50, and the cleavage surface is defective during the cleavage, resulting in a low cleavage yield.

On the other hand, for example, when polishing is performed until the thickness of the n-GaN substrate 50 becomes about 50 to 80 μm, the thickness of the n-GaN substrate 50 becomes small, so that the cleavage can be easily performed. The yield of cleavage is improved.

However, when the n-GaN substrate 50 is polished to a thickness of 50 to 80 μm,
Of the n-GaN substrate 50 and the layers 51 to 59 formed on the n-GaN substrate 50 are warped. As a result, there is a possibility that distortion occurs in each of the layers 51 to 59, particularly the MQW active layer 55. In addition, cleaving the warped n-GaN substrate 50 is more difficult than cleaving a flat substrate, which makes the cleavage operation difficult. In addition, the n-GaN substrate 5 having a very high hardness
Since it takes a long time to polish 0 to such a thickness, the manufacturing efficiency of the semiconductor laser device is reduced and the manufacturing cost is increased. Therefore, such a method is not suitable for mass production of semiconductor laser devices.

An object of the present invention is to provide a nitride-based semiconductor device having a high yield in a cleavage step and capable of mass production, and a method of manufacturing the same.

[0012]

Means for Solving the Problems and Effects of the Invention As a result of various experiments and studies conducted by the present inventors, the surface roughness of the back surface of the GaN substrate (the surface opposite to the surface on the crystal growth layer side) was determined. By setting the thickness of the GaN layer to a predetermined value or less, the GaN
Even when the thickness of the substrate is relatively large, Ga
It has been found that the N substrate can be cleaved. And based on this result, the following invention was devised.

In the nitride semiconductor device according to the present invention, an active element region made of a nitride semiconductor is formed on one surface of a nitride semiconductor substrate, and the thickness of the nitride semiconductor substrate is 120 μm or more and 200 μm or more. The other surface of the nitride-based semiconductor substrate has an uneven shape including a concave portion having a depth of 0.1% or less of the thickness of the nitride-based semiconductor substrate.

The active element region of the nitride-based semiconductor device in this case is, for example, a light-emitting layer or active layer of a light-emitting diode device or a semiconductor laser device, a core layer of a waveguide device,
It corresponds to an I (intrinsic) layer of an N photodiode, a pn junction of a photodiode or HBT (heterojunction bipolar transistor), a channel of an FET (field effect transistor), and the like.

In the nitride semiconductor device according to the present invention, the depth of the concave portion in the uneven shape on the other surface (hereinafter referred to as the back surface) of the nitride semiconductor substrate is smaller than the thickness of the nitride semiconductor substrate. 0.1% or less. In such a nitride-based semiconductor substrate, crystal defects such as fine cracks introduced near the back surface are sufficiently removed by polishing the back surface or the like.

In a nitride-based semiconductor device provided with the above-described nitride-based semiconductor substrate, even if the thickness of the nitride-based semiconductor substrate is relatively large, ie, 120 μm or more and 200 μm or less, the nitride-based semiconductor substrate is formed on the substrate and the substrate. It is possible to cleave the active element region easily and without causing a cleavage surface defect or the like. Therefore, when such a nitride-based semiconductor device is manufactured, the yield is improved in the cleavage step.

By the way, when the above-mentioned nitride-based semiconductor device is manufactured, before the cleavage step, the nitride-based semiconductor substrate is polished in advance to a thickness that allows cleavage.

Here, in the above-mentioned nitride-based semiconductor device, cleavage can be performed even if the thickness of the nitride-based semiconductor substrate is relatively large, so that the time required for the above-mentioned polishing can be reduced. It becomes possible. Thereby, in the above-mentioned nitride-based semiconductor device, it is possible to manufacture at high manufacturing efficiency and at low cost. Such a nitride semiconductor device is suitable for mass production.

Further, in the above nitride semiconductor device, the thickness of the nitride semiconductor substrate is not less than 120 μm and not more than 20 μm.
Since it is relatively large, that is, 0 μm or less, the mechanical strength of the nitride-based semiconductor substrate is sufficient, and the occurrence of warpage in the nitride-based semiconductor substrate can be prevented. Therefore, in such a nitride-based semiconductor device, it is possible to prevent the occurrence of distortion in the active device region. Thereby, in the nitride-based semiconductor device, good device characteristics are realized.

In the above, it is preferable that the thickness of the nitride-based semiconductor substrate is from 120 μm to 150 μm. Cleavage can be more easily performed on a substrate having such a thickness. Therefore, the yield in the cleavage step is further improved.

The nitride semiconductor substrate and the active element region may be made of a nitride semiconductor containing at least one of gallium, aluminum and indium.
In this case, by adjusting the composition of the nitride semiconductor in the active element region, a nitride semiconductor element having desired characteristics can be obtained.

The nitride-based semiconductor substrate may be composed of GaN. Further, the nitride-based semiconductor substrate may be made of AlGaN. Since the nitride-based semiconductor substrate composed of such a material has extremely high hardness, it has a long polishing time.

Here, in the above-mentioned nitride semiconductor device, the thickness of the nitride semiconductor substrate is 120
Since it is relatively large, that is, not less than μm and not more than 200 μm, the amount of polishing the nitride-based semiconductor substrate made of a material having high hardness may be small. Therefore, in this case,
The time required for polishing can be significantly reduced.
Thereby, in this case, more effective effects can be obtained in improving the manufacturing efficiency and reducing the manufacturing cost.

The nitride-based semiconductor substrate and the active element region may have a cleavage plane perpendicular to the substrate surface of the nitride-based semiconductor substrate.

According to a method of manufacturing a nitride-based semiconductor device according to the present invention, a step of forming an active device region made of a nitride-based semiconductor on one surface of a nitride-based semiconductor substrate; Of the nitride-based semiconductor substrate until the thickness of the nitride-based semiconductor substrate becomes 120 μm or more and 200 μm or less and the depth of the concave-convex concave portion of the other surface of the nitride-based semiconductor substrate becomes 0.1% or less of the thickness of the nitride-based semiconductor substrate. Polishing the other surface.

In the method of manufacturing a nitride-based semiconductor device according to the present invention, the other surface of the nitride-based semiconductor substrate
Polishing is performed so that the depth of the concave portion in the concave and convex shape (referred to as the back surface) is 0.1% or less of the thickness of the nitride-based semiconductor substrate. In such a nitride-based semiconductor substrate, crystal defects such as fine cracks introduced near the back surface are sufficiently removed by polishing the back surface or the like.

In the above method, even if the thickness of the nitride-based semiconductor substrate is relatively large from 120 μm to 200 μm by forming such a nitride-based semiconductor substrate, in the cleavage step, the substrate and the substrate are separated. It is possible to cleave the active element region formed thereon easily and without causing a defect in the cleavage plane or the like. Therefore, it is possible to improve the yield in the cleavage step.

In the above method, before the cleavage step, the nitride-based semiconductor substrate is polished in advance to a thickness that allows cleavage. Here, in this case, since the cleavage can be performed even if the thickness of the nitride-based semiconductor substrate is relatively large as described above, the time required for the above-described polishing can be reduced. Therefore, according to the above method, it is possible to improve the manufacturing efficiency of the nitride-based semiconductor device and to reduce the manufacturing cost.

In the above method, since the thickness of the nitride-based semiconductor substrate is relatively large from 120 μm to 200 μm, the nitride-based semiconductor device manufactured by the above-mentioned method has The mechanical strength of the substrate is sufficient, and the occurrence of warpage in the nitride-based semiconductor substrate is prevented. In such a nitride-based semiconductor device, since distortion is prevented from being generated in the active device region, good device characteristics can be realized.

As described above, according to the above-described method for manufacturing a nitride-based semiconductor device, a nitride-based semiconductor device having good device characteristics can be manufactured at a high yield. Therefore, according to such a method, mass production of nitride-based semiconductor elements can be realized.

After the step of polishing the nitride-based semiconductor substrate, a step of forming a cleavage plane perpendicular to the substrate surface of the nitride-based semiconductor substrate in the nitride-based semiconductor substrate and the active element region may be further provided.

[0032]

FIG. 1 is a schematic sectional view showing an example of a nitride semiconductor device according to the present invention. In this case, a nitride semiconductor laser device will be described as the nitride semiconductor device.

The GaN-based semiconductor laser device 10 shown in FIG.
0 denotes an n-buffer layer 2 and an n-
Cladding layer 3, active layer 4, p-cladding layer 5, and p-
The contact layers 6 are sequentially laminated. These layers 2
6 comprises a compound semiconductor represented by the general formula In _x Al _y Ga _1-xy N.

In the above-described semiconductor laser device 100, by adjusting the composition of In, Al, and Ga in each of the layers 2 to 6 (ie, the values of x and y), it is possible to realize blue light emission having a wide wavelength selectivity. Is possible.

In the above composition of each of the layers 2 to 6,
x and y are 0 ≦ x ≦ 1, 0 ≦ y ≦ 1,
Further, x and y satisfy the relationship of x + y = 1.

The above-described semiconductor laser device 100 is manufactured by the following method. When manufacturing the semiconductor laser device 100, first, as shown in FIG.
An n-buffer layer 2, an n-cladding layer 3, an active layer 4, and an n-GaN layer 1 are formed on an n-GaN substrate 1 having a predetermined thickness in the range of μm by MOCVD (metal organic chemical vapor deposition) or the like.
The p-cladding layer 5 and the p-contact layer 6 are continuously grown.

In this case, the normal pressure MOCV
The layers 2 to 6 are grown by the D method. That is, each
During the growth of the layers 2 to 6, the growth pressure is 1 atm (about 1 atm).
00 kPa) and H_TwoAnd N_TwoCarrier gas consisting of
Source gas together with the source gas. As the source gas, G
a (CH_Three)_Three, In (CH_Three)_Three, Al (CH_Three) _Three
And NH_ThreeIs used.

Here, in this case, Ga (CH ₃ ) ₃ , In (CH ₃ ) ₃ , Al
By adjusting the ratio of each of (CH ₃ ) ₃ and NH ₃ , Ga, In, Al
Is adjusted.

Further, the n-buffer layer 2 and the n-
During the growth of the doped layer 3, the SiH _FourThe dopant gas
Will be introduced further. Thereby, as an n-type impurity
N-buffer layer 2 doped with Si and n-
The lad layer 3 is formed.

On the other hand, the p-cladding layer 5 and the p-contour
In growing the contact layer 6, Cp _TwoMg as dopant
Further introduction as gas. Thereby, p-type impurities and
The p-cladding layer 5 and p
A contact layer 6 is formed;

Although Si is used as the n-type impurity in this case, Se or the like may be used instead of Si. In this case, Mg is used as the p-type impurity, but Be, Zn, or the like may be used instead of Mg.

Although the layers 2 to 6 are grown by the normal pressure MOCVD method in the above description, the layers 2 to 6 may be grown by the reduced pressure MOCVD method.

Each layer 2 of In _x Al _y Ga _1-xy N
Table 1 shows compositions (x, y) and carrier concentrations of Nos. 6 to 6.

[0044]

[Table 1]

In the semiconductor laser device 100 described above,
The n-buffer layer 2 is a layer formed for improving the crystallinity of the active layer 4. Note that such an n-buffer layer 2 is not always necessary for a semiconductor laser device. Therefore, a structure without the n-buffer layer 2 is also possible.

The n-cladding layer 3 is a layer constituting the n-side of the pin junction forming the light emitting region. Such n-
In the cladding layer 3, the composition (x, y) is appropriately adjusted depending on the desired wavelength of the laser beam.

The active layer 4 is substantially composed of an intrinsic semiconductor, and is a layer serving as the center of the light emitting region. In such an active layer 4, the composition (x, y) is appropriately adjusted according to the wavelength of a desired laser beam.

The p-cladding layer 5 is a layer constituting the p-side of the pin junction forming the light emitting region. Such p-
In the clad layer 5, the composition (x, y) is appropriately adjusted depending on the desired wavelength of the laser light in consideration of the relationship between the n-clad layer 3 and the active layer 4.

Here, in this case, n-cladding layer 3 and p-cladding layer 5 are formed such that the band gap of n-cladding layer 3 and p-cladding layer 5 becomes larger than the band gap of active layer 4. The composition (x, y) is adjusted. Thereby, the amount of carriers injected into the active layer 4 can be increased, and the emission intensity of the semiconductor laser device 100 can be improved. As described above, the semiconductor laser device 100 of the present embodiment is a semiconductor laser device having a double hetero (DH) structure.

The p-contact layer 6 is provided with a p-electrode 15 described later.
This is for providing an ohmic contact surface with the substrate.

As described above, the semiconductor wafer 90 having the layers 2 to 6 formed on the n-GaN substrate 1 is manufactured. Thereafter, the semiconductor wafer 90 is taken out of the CVD furnace.

Subsequently, an oxide film such as a SiO ₂ film is formed on the entire upper surface of the p-contact layer 6 of the semiconductor wafer 90 by a sputtering method or a CVD method. Next, a photoresist pattern is formed on the upper surface of the oxide film by a predetermined photolithography technique, and the oxide film is selectively etched based on the photoresist pattern.

As described above, an etching mask (not shown) made of an oxide film and a photoresist is formed on a predetermined region of p-contact layer 6.

Subsequently, as shown in FIG. 2A, a partial region of the p-contact layer 6 and the p-cladding layer 5 is etched by using the above-mentioned etching mask (not shown). The cladding layer 5 is exposed. In this way,
A ridge portion 10 having a width of about 10 μm constituted by the p-contact layer 6 and the p-cladding layer 5 is formed. Thereafter, the etching mask is removed and the semiconductor wafer 90 is cleaned.

Further, a p-electrode 15 is formed on the upper surface of the p-contact layer 6 of the ridge 10. In this case, a metal film such as a Ni film, a Pd film, or a Pt film is deposited on the surface of the semiconductor wafer 90 by a sputtering method, an electron beam evaporation method, or the like, and the p-electrode 15 is formed by performing a predetermined slide etching or the like. Form.

Subsequently, the back surface (the surface opposite to the crystal growth layer side) of the n-GaN substrate 1 is polished. Hereinafter, details of the polishing step will be described.

FIG. 3 is a schematic view showing a polishing step of the n-GaN substrate 1, and FIG. 4 is a partially enlarged view of a region indicated by a broken line A in FIG.

As shown in FIGS. 3 and 4, in the polishing step, a buff 31 is laid on a substrate 30 made of glass or the like having a flat surface. Then, water or oil is flowed on the buff 31 and an abrasive (not shown) such as diamond, silicon oxide, or alumina is arranged. In this case, the abrasive particles have a roughness of about 0.2 to 1 μm, preferably about 0.2 to 0.5 μm.

On the other hand, a wax 21 is applied to the surface of the semiconductor wafer 90 on the crystal growth layer side to protect the surface, and the semiconductor wafer 90 is attached to the holder (polishing jig) 20 with the crystal growth layer side up. And fix it.

The holder 20 is formed so as to be rotatable in the direction of arrow R and to be movable in the vertical direction (direction of arrow S).

After attaching the semiconductor wafer 90 to the holder 20, the holder 20 is rotated in the direction of the arrow R and the back surface of the n-GaN substrate 1 is pressed against the abrasive to perform polishing.

In such a polishing step, n-Ga
Polishing is performed until the thickness of the N substrate 1 becomes about 120 to 200 μm and the surface roughness on the back surface of the n-GaN substrate 1 becomes 0.1% or less of the thickness of the substrate.

In this case, the surface roughness on the back surface of the n-GaN substrate 1 corresponds to the depth of the concave portion of the uneven shape on the back surface of the n-GaN substrate 1. In this case, nG
The surface roughness of the back surface of the aN substrate 1 is measured by, for example, a measurement method (AFM method) using an atomic force microscope (AFM).

For example, in the process shown in FIG.
When each of the layers 2 to 6 is grown on the n-GaN substrate 1 of 00 μm, in the polishing step shown in FIGS.
Polishing is performed until the thickness of the aN substrate 1 becomes 120 μm and the surface roughness on the back surface of the n-GaN substrate 1 becomes 100 nm or less, more preferably 30 nm or less.

Note that 120 to 200 μm
In the case where the n-GaN substrate 1 having a thickness within the range described above is used, the thickness of the n-GaN substrate 1 does not need to be further reduced in the polishing step. In this case, n-
Polishing may be performed so that the surface roughness of the back surface of the GaN substrate 1 is in the above range.

Here, considering the cleavage step described later,
The thickness of the n-GaN substrate 1 after polishing is 120 to 150 μm
It is preferred that it is about. Therefore, 1
It is preferable to use an n-GaN substrate having a thickness of about 20 to 150 μm, or to perform polishing until the thickness becomes about 120 to 150 μm.

After the back surface of the n-GaN substrate 1 is polished until it reaches a predetermined smoothness as described above, the semiconductor wafer 90 is removed from the holder 20 and the semiconductor wafer 90 is cleaned. After that, a metal film such as a Ti film, an Al film, or a Ni film is deposited on the back surface of the n-GaN substrate 1 by a sputtering method or a vacuum evaporation method to form an n-electrode 16.

Subsequently, the semiconductor wafer 90 is divided by cleavage to form an end face, and a resonator is manufactured. Further, the semiconductor wafer 90 is separated into individual devices by cleavage, and the semiconductor laser device 100 shown in FIG. 1 is manufactured.

Here, in this case, as described above, the back surface of the n-GaN substrate 1 is polished until it reaches a predetermined smoothness. Therefore, on the back surface of the n-GaN substrate 1, crystal defects such as minute cracks introduced near the back surface are sufficiently removed by polishing the back surface or the like. In such an n-GaN substrate 1, a thickness of 120 to
Even if it is as large as 200 μm, it is possible to easily cleave without causing a defect in the cleavage plane. As a result, the yield in the cleaving process of manufacturing the resonator and separating the elements is improved.

In particular, when the thickness of the n-GaN substrate 1 is 120 to
When the thickness is 150 μm, the cleavage step can be performed more easily, and the yield in the cleavage step is further improved.

As described above, each semiconductor laser element 10
After the separation, the semiconductor laser devices 100 are finally mounted on predetermined stems, and wire bonding is performed. The semiconductor laser device is manufactured as described above.

As described above, in the above-described method for manufacturing a semiconductor layer laser device, cleavage is conventionally performed in order to reduce the surface roughness of the back surface of the n-GaN substrate 1 to 0.1% or less of the thickness of the substrate. Even in the case of the n-GaN substrate 1 having a large thickness, which has been difficult, the cleavage can be easily performed without causing a defect in the cleavage plane. Thereby, the yield in the cleavage step is improved.

In this case, the thickness of the n-GaN substrate 1 after the polishing step may be larger than the thickness of the conventional n-GaN substrate. It is possible to reduce the length as compared with the case of Therefore, at the time of manufacturing the semiconductor laser device 100, the manufacturing efficiency is improved and the manufacturing cost is reduced.

The above-described semiconductor laser device 100
Since the thickness of the n-GaN substrate 1 is as large as 120 to 200 μm, it is mechanically stable, and the occurrence of warpage is prevented. The work of cleaving the flat n-GaN substrate 1 is easier than the work of cleaving the warped n-GaN substrate 1. Therefore, in the semiconductor laser device 100, the yield of the assembly process is improved.

Further, since the warpage is prevented as described above, there is no possibility that distortion such as stress and strain is generated in each of the layers 2 to 6 formed on the n-GaN substrate 1, particularly, the active layer 4. . Therefore, in such a semiconductor laser device 100, the device characteristics are improved, for example, the luminous efficiency is improved and the leak current is reduced.

As described above, according to the method for manufacturing a semiconductor laser device described above, it is possible to manufacture the GaN-based blue light emitting semiconductor laser device 100 having good device characteristics at a high yield. Therefore, such a method
It may be suitable for mass production of semiconductor laser devices.

In the above description, the case where the layers 2 to 6 are grown on the n-GaN substrate 1 and then the back surface of the n-GaN substrate 1 is polished has been described.
Polishing one surface (back surface) of the GaN substrate 1,
The layers 2 to 6 may be grown on the other surface of the n-GaN substrate 1. In this case, the same effect as above can be obtained.

In this case, in this case, the thickness of the n-GaN substrate 1 is previously set to 120 to 200 μm by polishing.
m, preferably 120 to 150 μm.

In the above, n-GaN substrate 1 has n
Although the semiconductor laser device 100 in which the p-type semiconductor layer and the p-type semiconductor layer are sequentially formed has been described, a semiconductor laser device in which a p-type semiconductor layer and an n-type semiconductor layer are sequentially formed on a p-GaN substrate may be used. Good. In this case, the same effect as described above can be obtained by polishing the back surface of the p-GaN substrate (the surface opposite to the crystal growth side) by the same method as described above.

In the above, the case where the present invention is applied to a semiconductor laser device has been described. However, the present invention may be applied to a semiconductor light emitting device other than the semiconductor laser device, for example, a light emitting diode. Further, the present invention can be applied to semiconductor devices other than the semiconductor light emitting device as long as the semiconductor device uses a nitride-based semiconductor substrate.

In the above description, the case where a GaN substrate is used as the nitride semiconductor substrate has been described. However, in the present invention, a nitride semiconductor substrate made of a nitride semiconductor other than GaN can be used. . For example, an AlGaN substrate, an AlN substrate, or the like can be used as the nitride-based semiconductor substrate.

[0082]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the preferred embodiment, the method shown in FIGS.
The surface roughness of the back surface of the aN substrate 1 is about 0.01 of the thickness of the substrate.
A plurality of different samples were prepared within a range of about 0.4%. Then, the yield of each sample in the cleavage step at the time of manufacturing the resonator was determined.

In this case, the samples in which the cleavage plane was defective in producing the resonator were regarded as defective products, and the yield was determined by removing these samples.

In this case, the thickness of n-GaN substrate 1 after the polishing step shown in FIGS.
μm, 160 μm, and 200 μm.
For each case of μm, the yield in the cleavage step was determined.

FIG. 5 shows the results of the example. As shown in FIG. 5, the thickness of the n-GaN substrate 1 is 120 μm and 160 μm.
m and 200 μm, nG
The surface roughness on the back surface of the aN substrate 1 is set to 0.
It became clear that the cleavage yield was high in the range of 1% or less. The thickness of the n-GaN substrate 1 is 160
It has been clarified that the cleavage yield is higher in the case of μm than in the case of the thickness of 200 μm, and further higher in the case of the thickness of 120 μm.

For comparison, when the thickness of the n-GaN substrate 1 exceeds 200 μm, here, when the thickness is 250 μm, the cleavage yield is obtained in the same manner as described above. In this case, the cleavage yield is obtained. Was found to be as low as 15% or less as a whole.

From the above results, it was found that the yield of cleavage of the device was improved by setting the surface roughness on the back surface of the n-GaN substrate 1 to 0.1% or less of the thickness of the substrate. Further, in this case, it is preferable that the thickness of the n-GaN substrate 1 be about 120 to 160 μm, and it has been found that the cleavage yield is improved thereby.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a nitride-based semiconductor laser device according to the present invention.

FIG. 2 is a schematic process sectional view illustrating a method for manufacturing the nitride-based semiconductor laser device of FIG.

FIG. 3 is a schematic view showing a polishing step of the nitride-based semiconductor laser device of FIG.

FIG. 4 is a partially enlarged sectional view of FIG. 3;

FIG. 5 is a view showing a result of an example.

FIG. 6 is a schematic sectional view showing an example of a conventional nitride-based semiconductor laser device using a GaN substrate.

[Explanation of symbols]

 Reference Signs List 1 n-GaN substrate 2 n-buffer layer 3 n-cladding layer 4 active layer 5 p-cladding layer 6 p-contact layer 15 p-electrode 16 n-electrode 20 holder 21 wax 30 substrate 31 buff 100 semiconductor laser element

Claims (8)

[Claims] An active element region formed of a nitride-based semiconductor is formed on one surface of a nitride-based semiconductor substrate, and the nitride-based semiconductor substrate has a thickness of not less than 120 μm and not more than 200 μm, and A nitride-based semiconductor device, characterized in that the other surface of the semiconductor substrate has an uneven shape including a concave portion whose depth is 0.1% or less of the thickness of the nitride-based semiconductor substrate. 2. The nitride-based semiconductor substrate has a thickness of 120.
2. The nitride-based semiconductor device according to claim 1, wherein the thickness is not less than 150 μm and not more than μm. 3. The nitride according to claim 1, wherein said nitride semiconductor substrate and said active element region are made of a nitride semiconductor containing at least one of gallium, aluminum and indium. Material semiconductor device. 4. The nitride-based semiconductor device according to claim 1, wherein said nitride-based semiconductor substrate is made of GaN. 5. The nitride semiconductor device according to claim 1, wherein said nitride semiconductor substrate is made of AlGaN. 6. The nitride semiconductor substrate and the active element region have a cleavage plane perpendicular to a substrate surface of the nitride semiconductor substrate. Nitride based semiconductor devices. 7. A step of sequentially forming an active element region made of a nitride-based semiconductor on one surface of a nitride-based semiconductor substrate, wherein the thickness of the nitride-based semiconductor substrate is not less than 120 μm and not more than 200 μm.
μm or less, and the other side of the nitride-based semiconductor substrate until the depth of the concave portion of the uneven shape of the other surface of the nitride-based semiconductor substrate becomes 0.1% or less of the thickness of the nitride-based semiconductor substrate. Polishing the surface of the nitride semiconductor device. 8. After the polishing step of the nitride-based semiconductor substrate, the method further comprises the step of forming a cleavage plane perpendicular to the substrate surface of the nitride-based semiconductor substrate in the nitride-based semiconductor substrate and the active element region. The method for manufacturing a nitride-based semiconductor device according to claim 7, wherein