JP2000114664A - Nitride semiconductor laser element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reliable long-life nitride semiconductor laser element, by preventing flaking of a p-type electrode and improving heat radiating characteristics even when a resonance face is formed by cleavage in a more practical way. SOLUTION: A nitride semiconductor laser element includes a ridge-shaped stripe with an insulating film 62 on a side of the stripe. An insulating protective film 201 is formed from a part of a p-type electrode 20 on the uppermost layer of the stripe to the side face of the ridge-shaped stripe. A p-type pad electrode 101 connected electrically with the p-type electrode 20 is formed by cleavage on the insulating protective film 201.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a nitride semiconductor (In _a A
_{l b Ga 1-ab N,} 0 ≦ a, 0 ≦ b, relates laser element consisting of a + b ≦ 1), and prevention and when the resonance surface forming, in operation, the peeling of the p-electrode, in particular by cleavage life characteristics and The present invention relates to a nitride semiconductor laser device capable of obtaining a device having good heat dissipation with good productivity.

[0002]

2. Description of the Related Art In recent years, much research and development has been carried out for practical use of nitride semiconductor laser devices, and various nitride semiconductor laser devices are known. For example, the present inventors have proposed that Jpn.J.Appl.Phys.
l.37 (1998) pp.L309-L312, Part2, No.3B, 15 March 1998
And a partially formed SiO 2 on the sapphire substrate
_A plurality of nitride semiconductor layers serving as a laser element structure are stacked on a nitride semiconductor substrate made of n-GaN selectively grown through _two films, the sapphire substrate is removed, and a resonance surface is formed by cleavage. As a result, a nitride semiconductor laser device capable of continuous oscillation at room temperature for 10,000 hours or more has been announced. FIG. 7 shows a schematic cross-sectional view similar to the laser device shown in the above-mentioned JJAP. As shown in FIG. 7, the p-Al contact layer made of p-GaN
A ridge-shaped stripe is formed by partially etching the p-side cladding layer having a superlattice structure of _0.14 Ga _0.86 N / GaN. A p-electrode is formed on the stripe, and a resonance surface is formed by cleavage. It is a nitride semiconductor laser device made of. Further, in this laser element, a p pad electrode is formed so as to cover the p electrode. The p electrode is
In addition to flowing a current through the laser element, it also serves as an intervening body for conducting heat generated inside the laser element to the p-pad electrode and dissipating it outside. The p-pad electrode radiates the heat generated in the nitride semiconductor laser element to the outside of the element via a heat-conductive p-electrode or the like, or conducts and dissipates the heat to a heat absorbing material. The p-pad electrode enlarges a substantial surface area of the p-electrode so that the p-electrode side can be wire-bonded or directly bonded, and further prevents a defect from occurring in the element due to an impact due to stress at the time of bonding. . In terms of heat dissipation, the good adhesion between the p-electrode and the p-pad electrode allows better dissipation of heat generated during driving of the laser element, and further improves the life characteristics.

[0003]

However, some of the obtained laser elements have poor life characteristics, that is, those that are considered to be deteriorated due to electrode peeling, and those that are likely to be deteriorated due to insufficient heat dissipation. May occur. This is probably because the p-electrode and the p-side nitride semiconductor layer, which is the uppermost layer of the ridge-shaped stripe, are separated or are about to be separated due to an impact when the resonance surface is formed by cleavage. It is considered that the heat generated in the laser element cannot be efficiently conducted to the p-pad electrode when a part thereof is separated from the p-side nitride semiconductor layer. In order to prevent peeling of the p-electrode, it is conceivable to select a metal having good adhesion to the p-side nitride semiconductor layer as the p-electrode formed at the top of the ridge-shaped stripe. A metal that can be a p-electrode having ohmic properties is selected within a limited range. The peeling of the p-electrode may cause a reduction in the life characteristics and reliability of a practicable laser element, and it is desirable to solve the problem from the viewpoint of improving productivity in putting the laser element to practical use.

Accordingly, an object of the present invention is to prevent the p-electrode from peeling off and improve heat dissipation even if the resonance surface is formed by cleavage, so as to further improve the practicability. It is to provide a nitride semiconductor laser device having a good quality.

[0005]

That is, the object of the present invention is to
This can be achieved by the following configurations (1) to (4). (1) A ridge-shaped stripe having an insulating film on the side surface of the stripe, a p-electrode on the uppermost layer of the stripe, and cleavage formed in a direction perpendicular to the length direction of the ridge-shaped stripe. A nitride semiconductor laser device having a resonance surface on the cleaved cleavage surface, having an insulating protective film formed from a part of the p-electrode to the side surface of the ridge-shaped stripe, and further electrically connecting the p-electrode to the p-electrode. A nitride semiconductor laser device having a p-pad electrode formed by connection. (2) The nitride semiconductor according to (1), wherein the insulating protective film is formed so as to cover at least a part of both sides of the p-electrode in parallel to a ridge-shaped stripe length direction. Laser element. (3) The insulating protective film formed on a part of both sides of the p-electrode is continuously formed up to a part of the p-electrode above the cleavage plane. Nitride semiconductor laser device. (4) The insulating protective film is made of SiO ₂ , TiO ₂ and A
The nitride semiconductor laser device according to any one of (1) to (3), wherein the nitride semiconductor laser device is at least one of l ₂ O ₃ .

That is, according to the present invention, by covering a part of the p-electrode from the ridge-shaped side surface with an insulating protective film, separation of the p-electrode due to cleavage is prevented, heat dissipation is improved, and reliability and life characteristics are improved. Can be provided. Furthermore, productivity is improved by the above configuration. It is considered that the improvement in heat dissipation due to the prevention of the separation of the p-electrode is due to the efficient conduction of heat from the p-electrode to the p-pad electrode. Also,
Since the insulating protective film of the present invention is further formed on the insulating film on the side surface of the ridge-shaped stripe, the insulating property of the laser element is reinforced, and the reliability of the laser element is improved (prevention of failure). It is preferred in terms of. In the present invention, forming an insulating protective film from a part of the p-electrode to the side surface of the ridge-shaped stripe means that a part other than the p-electrode in the side surface direction of the ridge-shaped stripe covers an area of the p-electrode, such as an insulating film. a side surface of a p-side nitride semiconductor layer, or a substrate,
It shows that it forms so that it may apply. The insulating protective film is
It acts to hold down the p-electrode and prevent peeling from the p-side nitride semiconductor layer at the uppermost layer of the ridge-shaped stripe. The present invention does not adversely affect various characteristics of the laser element by installing the insulating protective film as described above,
Further, the manufacturing process can be performed simply and efficiently, and the above problem can be solved.

As described above, the necessity of adding the function of preventing the p-electrode formed on the upper part of the ridge-shaped stripe from being peeled off to the laser element is considered to be the practicality that enables the present inventors to perform continuous oscillation for a long time. The realization of a laser device with a high level of operation has led to severe operating conditions, and it has become necessary to overcome the slight inadequacies in previously unforeseen parts in order to commercialize the laser device. . In order to cope with such a need, the present invention forms the insulating protective film as described above in order to reduce the possibility that the device is likely to be degraded during the operation of the laser device due to slight peeling due to cleavage of the p-electrode. By doing so, it can be improved.

In the present invention, it is preferable that the insulating protective film is formed so as to cover at least a part of both sides of the p-electrode in parallel with the length direction of the ridge-shaped stripe in order to prevent the p-electrode from peeling off. . Further, in the present invention, the insulating protective film formed on a part of both sides of the p-electrode is continuously formed up to a part of the p-electrode formed on the cleavage plane and on the ridge-shaped stripe. In this case, the adhesion force of the p-electrode above the cleavage plane where a physical force is likely to be applied when cleaving can be increased, and peeling of the p-electrode can be better prevented. Here, when an insulating protective film is formed near the cleavage plane of the p-electrode formed on the ridge-shaped stripe, the thermal conductivity of the insulating protective film is inferior to that of the p-electrode. It is desirable to form an insulating protective film from the viewpoint of heat dissipation so that the contact of the p-pad electrode having a function of dissipating heat with the p-electrode is not hindered as much as possible. Further, in the present invention, the insulating protective film is formed of S
When at least one of TiO ₂ , TiO _2, and Al ₂ O ₃ is used, peeling of the p-electrode can be favorably prevented, which is preferable in terms of insulating properties, and is further preferable in terms of line stability by simplifying the process. .

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A nitride semiconductor laser device according to the present invention has a p-electrode on the uppermost layer of a ridge-shaped stripe having an insulating film on the side surface of the stripe, and is perpendicular to the length direction of the ridge-shaped stripe. A cleavage surface formed by cleavage in various directions has a resonance surface, and an insulating protective film is formed from a part of the p-electrode to the side surface of the ridge-shaped stripe. And a p-pad electrode formed by being electrically connected. Before forming the p pad electrode, the insulating protective film according to the present invention prevents the p electrode from peeling off from the uppermost layer of the ridge-shaped stripe even when a physical force such as cleavage is applied. The electrode is formed from the p-electrode to a portion other than the p-electrode so as to press down a part of the electrode, for example, over the ridge-shaped stripe side surface.

FIG. 1 shows an embodiment of the present invention.
The present invention will be described in detail with reference to FIG. FIG. 1 is a schematic cross-sectional view showing a part of a nitride semiconductor laser device according to an embodiment in which an insulating protective film 201 is formed, which is cut perpendicular to the length direction of a ridge-shaped stripe. In FIG. 1, a p-electrode 20 is formed on the uppermost p-side contact layer 13 of a ridge-shaped stripe having an insulating film 62 on a side surface, and further on the p-electrode 20, as shown in FIG. A part of a nitride semiconductor laser device formed by forming an insulating protective film 201 on both sides of the ridge-shaped stripe 20 and the side surfaces of the ridge-shaped stripe, and forming a p-pad electrode thereon so as to be electrically connected to the p-electrode. It is shown. Further, FIG. 2 is a schematic plan view showing a part of the nitride semiconductor laser device in a state where the p-pad electrode is not formed in the schematic sectional view of FIG. 1 when a side having a ridge-shaped stripe is viewed from directly above. The figure is shown. The dotted line near the center in FIG. 2 shows the position of the ridge-shaped stripe that does not appear on the surface due to the formation of the p-electrode, and the two-dot chain line shows the position of the p-electrode, A part of the p-electrode which is covered with the insulating protective film and not exposed on the surface is shown. Further, R in FIG. 2 indicates a ridge-shaped stripe width, and P indicates a width when the p-electrode is viewed from above.

In the present invention, the insulating protective film 201 is
The ridge-shaped stripe may be formed so as to cover at least a part of the p-electrode and extend to the side surface of the ridge-shaped stripe. Preferably, as shown in FIGS. 1 and 2A, both sides of the p-electrode are partially covered. It is formed so as to be parallel to the length direction. Further, as shown in FIG. 2B, an insulating protective film covering both sides of the p-electrode is continuously in contact with the uppermost p-side contact layer 13 of the ridge-shaped stripe above the cleavage plane. When the insulating protection film 201 on the upper part of the cleavage surface is liable to receive an impact at the time of cleavage, the end of the p-electrode 20 is formed continuously on the p electrode [upper part of the cleavage plane having the ridge width R shown in FIG. 2B]. Since the portion is pressed, peeling of the p-electrode can be favorably prevented, which is preferable.

In the present invention, as the insulating protective film,
The material is not particularly limited as long as it has an insulating property, and is preferably a material having an insulating property and an adhesive force with an insulating film or the like constituting a laser element to such an extent that the p-electrode can be prevented from peeling off. And more preferably an insulating oxide. For example, specifically, SiO ₂ , TiO ₂ , Al ₂ O ₃ , Si
Examples of the material include any one or more of N and TaO _X , and preferably SiO ₂ , TiO ₂ , and A
Examples of the material include at least one of l ₂ O ₃ . Use of such a material is preferable for preventing peeling of the p-electrode. Further, the insulating protective film can reinforce the insulating property on the side surface of the ridge-shaped stripe of the laser element, and is also preferable from the viewpoint of improving the reliability (preventing failure) of the laser element. The thickness of the insulating protective film is not particularly limited,
For example, specifically, it is 0.01-1 μm, preferably 0.1-0.5 μm, more preferably 0.1 μm
Film thickness of the order. It is preferable that the thickness of the insulating protective film be in the above range in order to prevent peeling of the p-electrode. Forming the insulating protective film in consideration of the strength of the adhesive force with the portion constituting the laser element of the material of the insulating protective film, for example, the insulating film, and the thermal conductivity, and the like, The thickness and the like are adjusted.

In the present invention, as a method of forming an insulating protective film, a film is formed on a pattern by photolithography using a sputtering film forming method, and an insulating film is formed only on a portion to be formed.

The insulating film 6 used in the laser device of the present invention
2 is not particularly limited, for example, SiO ₂ used in FIG. 7 showing a conventional laser device, or a nitride semiconductor laser device having a stripe structure with a stripe width of 0.5 to 4.0 μm described later. Second preferred to form
Used as a protective film (insulating film) of Ti,
Examples include oxides containing at least one element selected from the group consisting of V, Zr, Nb, Hf, and Ta, BN, SiC, and AlN. In addition, a Si oxide can be used as a second protective film described later. In this case, a material which is more easily etched than the Si oxide is selected as a material for the first protective film described later.

The stripe structure of the laser device of the present invention is not particularly limited, but a preferable stripe structure is, for example, a stripe structure having a stripe width of 0.5 to 4.0 μm. When the stripe width is in the above range, it is preferable in terms of lowering the threshold value and stabilizing the horizontal and lateral modes. Examples of the laser device having a stripe having a narrow stripe width as described above include a laser device having a structure as shown in FIGS. These laser elements can be obtained by a stripe and electrode forming method (specifically described in Japanese Patent Application No. 10-126549) that can be formed with good reproducibility even if the stripe width is reduced. . The method will be described below with reference to FIG. In this method, a material is formed such that an etching rate of an etching process is different between a first protective film used for forming a stripe waveguide and an insulating second protective film formed on a side surface of the stripe. By selecting and performing the following steps, a stripe can be formed with good reproducibility, and an insulating second protective film having a uniform thickness can be formed at a predetermined position.

FIG. 6 is a schematic cross-sectional view showing a partial structure of a nitride semiconductor wafer in each step for explaining each step of a method of forming stripes and electrodes of a nitride semiconductor laser device. The cross-sectional view shown in FIG.
FIG. 3 shows a view when the substrate is cut in a direction perpendicular to a stripe waveguide formed by etching, that is, in a direction parallel to a resonance surface.

First, in a first step, as shown in FIG. 6C, a stripe-shaped first protection film 61 is formed on the uppermost p-side contact layer 13. This first
In the step (1), the first protective film 61 may be made of any material having a difference from the etching rate of the nitride semiconductor, regardless of the insulating property. Further, the first protective film 61
For forming the second protective film 62, it is preferable to use a material having an etching rate different from that of the second protective film 62 formed in a third step described later. As the first protective film 61, for example, a Si oxide (including SiO ₂ ), a photoresist and the like can be cited, and preferably a Si oxide. When the first protective film 61 is made of Si oxide, wet etching, dry etching, or the like is used as a method of forming a stripe-shaped waveguide region of the nitride semiconductor laser device in the next second step. Dry etching, which is easy to etch, is preferably used, and the selectivity between the first protective film 61 and the nitride semiconductor which is regarded as important in this dry etching can be improved. Further, when the first protective film 61 is selected from the above-described materials, the property that the first protective film 61 is more easily dissolved in the acid than the second protective film in the etching performed by using the acid in the third process, which is a later process. Having a solubility difference with the second protective film 62,
In particular, it is preferable to use hydrofluoric acid as the acid used in the third step, since it is easily dissolved in hydrofluoric acid. The stripe width (W) of the first protective film is 4 μm to 0.5 μm,
Preferably, it is adjusted to 3 μm to 1 μm. First protective film 6
The stripe width of 1 roughly corresponds to the stripe width of the waveguide region.

In the first step, specific steps for forming the first protective film 61 include the steps shown in FIGS. 6A and 6B. First, as shown in FIG.
After forming the first protective film 61 on almost the entire surface of the p-side contact layer 13, a stripe-shaped third protective film 63 is formed on the first protective film 61. Then, FIG.
As shown in FIG. 7, after the first protective film 61 is etched while the third protective film 63 is attached, the third protective film 63 is removed.
Is removed, a striped first protective film 61 as shown in FIG. 6C can be formed. The etching gas or the etching means is changed while the third protective film 63 is attached, and the p-side contact layer 13 is changed.
It can also be etched from the side.

In the first step, etching means
Like RIE (Reactive Ion Etching)
Dry etching can be used.
In the first step, a first protective film 61 made of, for example, Si oxide
To etch _FourFluorine compounds such as
It is desirable to use the above gas.

Alternatively, the first protective film 61 in the form of a stripe as shown in FIG. 6C can be formed by a lift-off method. In the lift-off method, a photoresist having a shape in which a stripe-shaped hole is formed is formed on the p-side contact layer 13, a first protective film 61 is formed over the entire surface of the photoresist, and then the photoresist is dissolved and removed. By doing so, only the first protective film 61 in contact with the p-side contact layer 13 is left as shown in FIG. As a method of forming the first protective film 61, the first protective film 61 is formed by etching as shown in FIGS. 6A and 6B, rather than by forming the stripe-shaped first protective film 61 by a lift-off method. However, there is a tendency that a stripe having an almost perpendicular end face and a well-shaped shape is easily obtained.

Next, in a second step, as shown in FIG. 6D, a portion of the p-side contact layer 13 on which the first protective film 61 is formed is formed from a portion where the first protective film 61 is not formed. By etching, a stripe-shaped waveguide region corresponding to the shape of the protective film is formed immediately below the first protective film 61. When performing etching, the structure and characteristics of the laser element differ depending on the position of the etch stop. The etch stop may be stopped at any nitride semiconductor layer as long as it is a layer below the p-side contact layer. In the example shown in FIG. 6, the middle of the p-side cladding layer 12 below the p-side contact layer 13 is used as an etch stop. When the substrate side from the lower end face of the p-side cladding layer to the p-side contact layer in the direction of 0.2 μm is used as an etch stop, the stripe becomes a ridge, and a refractive index waveguide type laser device can be obtained. The lower end surface refers to the surface of the lowermost cladding layer in the thickness direction, and as described above, when the optical guiding layer is below the cladding layer, the interface between the guiding layer and the cladding layer is lower. Corresponds to the end face.
If the etch stop is higher than the lower end face, the etching time is shortened and the etching rate can be easily controlled, which is convenient in production technology.

Although not shown in FIG. 6, the etch stop may be a nitride semiconductor below the lower end surface of the p-side cladding layer. It is preferable that the layer closer to the substrate than the lower end surface is used as an etch stop, since the threshold value tends to be significantly reduced.

In the second step, as the etching means, wet etching, dry etching, or the like is used, but dry etching, which is easy to etch, is preferably used. For example, dry etching such as RIE (reactive ion etching) can be used. In this case, to etch a nitride semiconductor, another III-
Cl ₂ and CC commonly used in V-group compound semiconductors
Chlorine-based gases such as l ₄ and SiCl ₄ are used. When these gases are used, when the first protective film 61 is made of Si oxide, the selectivity with respect to Si oxide can be increased. Desirable.

Next, in the third step, as shown in FIG. 6E, the second protective film 62 is formed by using a different material from the first protective film 61 and using a material having an insulating property. Side surface of the waveguide, a plane of the nitride semiconductor layer (p-side cladding layer 12 in FIG. 6e) exposed by etching,
And on the first protective film 61. Second protective film 62
Is formed, the first protective film 61 is removed by etching, so that the second protective film 61 formed on the first protective film 61 is removed.
Only the protective film 62 is removed, and the second protective film 62 is continuously formed on the side surfaces of the stripe and the plane of the p-side cladding layer 12, as shown in FIG. As described above, in order to enable the first protective film 61 to be removed without etching the second protective film 62, as described above, the first protective film 61 and the second protective film 62 are formed. Material
This can be achieved by selecting and using different etching rates for the etching performed in the third step. Although the etching treatment in the third step is not particularly limited, for example, a dry etching method using hydrofluoric acid can be given.

The material of the second protective film 62 is selected from a material different from that of the first protective film 61, and has a lower or lower etching rate than the first protective film 61 in the etching process in the third step. The material is not particularly limited as long as the material can form the second protective film 62 on the side surface of the stripe or the like. Preferred second protective films include:
As described above, Si oxide and a resist material are preferably used for the first protective film 61, and therefore, the first protective film 61 is made of a material other than at least the material of the first protective film 61.
A material having a lower etching rate may be used. When the first protective film 61 is a Si oxide, specific examples of the second protective film 62 include Ti, V, Zr, Nb, Hf,
An oxide containing at least one element selected from the group consisting of Ta, at least one of BN, SiC and AlN is used, and more preferably an oxide of Zr, an oxide of Hf, or any of BN and SiC One or more materials are used. Further, since the nitride semiconductor is not etched after the formation of the second protective film 62, the second protective film 62 is not considered with respect to the etching speed with the nitride semiconductor. Further, as the second thin film layer 62, a Si oxide may be used. In this case, the first protective film 61 is made of a material having a higher etching rate in the third step than the Si oxide.

As described above, by continuously forming the second protective film on the first protective film 61, high insulation can be maintained and a uniform film thickness can be formed on the p-side cladding layer 12. Therefore, it is possible to prevent current concentration due to non-uniform film thickness. In the second step, the etch stop is made in the middle of the p-side cladding layer 12, so that the second protection film 62 is formed in the third step as shown in FIG. However, if the etch stop is made lower than the p-side cladding layer 12,
The second protective film is formed on the plane of the nitride semiconductor layer that has been etched.

The second protective film 62 can be formed by a lift-off method. For example, if the second protective film 62 is any of the specific examples described above and the first protective film 61 is a Si oxide, the second protective film 62 is more resistant to hydrofluoric acid than Si oxide. It has etching selectivity such that the etching rate is low or etching is difficult. Therefore, as shown in FIG. 6E, the second protection film is continuously formed on the side surface of the stripe waveguide, the plane on which the stripe is formed (etch stop layer), and the surface of the first protection film 61. After forming the first protective film 61 only by the lift-off method, the second protective film 62 having a uniform thickness with respect to the plane as shown in FIG.
Is formed.

Next, in a fourth step, as shown in FIG. 6 (g), on the second protective film 62 and the p-side contact layer 13, a p-type layer electrically connected to the p-side contact layer 13 is formed.
An electrode 20 is formed. Here, the second
When the p-electrode is formed, there is no need to perform a fine operation such as forming only the contact layer having a narrow stripe width, and the p-electrode can be formed in a large area, and the operability is good. Become.

In the present invention, when a ridge-shaped stripe having a narrow width as described above can be provided, the p-pad electrode formed on the p-electrode is not particularly limited, but preferably has at least a stripe length. A first thin film layer including a metal formed to cover the entire surface of the p-electrode with the same length as the first thin film layer, and a second thin film including a metal formed on the first thin film layer with a length shorter than the stripe length. When a third thin film layer is formed between the first thin film layer and the first thin film layer, the cleavage property of the p pad electrode is improved, which is preferable for preventing the p electrode from peeling off. . For example, a p-pad electrode 101 formed by forming a second thin film layer 32 on a first thin film layer 31 shown in FIG.

It is preferable that the first thin film layer is made of one or more of Ni, Ti, Cr, W, Pt and the like in view of cleavage property, adhesive property, heat radiation property and the like. The second thin film layer is made of Au.
Is preferable because the thermal conductivity is good and the heat dissipation is good, and further, the adhesiveness at the time of bonding and the relaxation of the impact are improved. The second thin film layer made of Au is inferior in cleaving property, but has a shape shorter than the stripe length. Therefore, the end face of the second thin film layer does not match the cleavage plane formed by cleavage, and the p-pad electrode Has no effect on the cleaving property. Further, Pt, W, and Pt are provided between the first thin film layer and the second thin film layer.
It is preferable to form a third thin film layer containing at least one or more materials such as TiN, Cr, and Ni because the third thin film layer becomes a barrier layer and metal of the second thin film layer can be prevented from diffusing. If the diffusion of the second thin film layer can be prevented in this way, the rise of the resistance and the rise of the threshold are suppressed, whereby the generation of heat inside the laser element is prevented, and the life characteristics are improved. preferable.

In the present invention, as the p and n electrodes,
Various materials can be appropriately selected and used. J. A. P. And the like having an ohmic contact described in (1).

When the n-electrode is formed on the back surface of the substrate, if the n-electrode is formed on the back surface of the substrate and then scribed from the back surface, the scribe may not reach the nitride semiconductor because of the n-electrode. In order to prevent this problem, scribing is facilitated by forming a pattern-shaped n-electrode on the back surface of the substrate of the wafer, and the cleavage property is improved. The pattern shape is preferably approximately the same as the size of the chip, for example, 400 μm × 400 μm, so that the shape of one chip obtained by cleaving the wafer is easily obtained. That is, an n-electrode is formed by forming a pattern so that the n-electrode does not exist on the scribe line and / or the cleavage plane. Further, if the metallized electrode is formed on the n-electrode in the same pattern shape as the n-electrode, it is easy to scribe and the cleavage property is improved. The n-electrode is not particularly limited. For example, Ti-Al, W-
Al-W-Au or the like can be used. Ti-Pt-Au- (Au / Sn) [film thickness 0.1 μm-0.2 μm-0.7 μm-0.3 μm] as a metallized electrode,
Ti-Pt-Au- (Au / Si) [thickness as above], Ti-Pt-Au- (Au / Ge) [thickness as above], Ti-Pt-Au-In [thickness as above] Similar],
Au / Sn [thickness 0.3 μm], In [thickness similar to the above], Au / Si [thickness similar to the above], Au / Ge [thickness similar to the above], and the like can be used. As a method of chipping when the n-electrode is formed in a pattern shape on the back surface, for example, a bar-shaped sample is formed by scribing from the back surface between the n-electrode patterns on the back surface, and a reflecting mirror is formed on the end surface and then scribed from the back surface. Chips can be formed.

The other device structures of the laser device of the present invention are not particularly limited, and various known device structures can be used. As the substrate on which the element structure of the laser element of the present invention is grown, a conventionally known substrate of a different kind such as sapphire or spinel, or Si on a different kind of substrate is used.
A nitride semiconductor substrate or the like obtained by forming a protective film made of a material on which a nitride semiconductor such as O ₂ does not grow or is unlikely to grow, and selectively performing lateral growth (lateral growth) thereon. No. Preferably, a nitride semiconductor substrate having few crystal defects obtained by lateral growth is preferable. When an element structure is formed on a nitride semiconductor substrate having few crystal defects, it is preferable to reduce the number of crystal defects in the nitride semiconductor constituting the element and to suppress heat generation in the element.
Further, it is preferable that the substrate is a nitride semiconductor substrate, because the substrate is easily cleaved and the p-electrode is prevented from peeling off. The protective film used for lateral growth has a different effect from the protective film used for forming the stripe.

The method for growing a nitride semiconductor substrate having few crystal defects obtained by using lateral growth is not particularly limited, and any method may be used. For example, JJAP Vol.
37 (1998) pp. L309-L312, and a nitride semiconductor grown on a heterogeneous substrate different from the nitride semiconductor described in Japanese Patent Application No. 9-290098 previously filed by the present applicant. An uneven portion is formed on the surface, and S
After the formation of the protective film such as iO _2, a method in which lateral growth is performed from the nitride semiconductor exposed on the side surface and the laterally grown nitride semiconductors are connected to each other on the protective film may be used. In addition, the nitride semiconductor substrate obtained by lateral growth may be grown with a heterogeneous substrate or with the heterogeneous substrate removed when growing the element structure.

The resonance surface of the laser device of the present invention is a {11-00} plane [M plane: a plane corresponding to the side surface of a hexagonal columnar crystal] of the nitride semiconductor so as to be perpendicular to the ridge-shaped stripe. By cleavage, a good mirror-like resonance surface can be formed. Regarding the cleavage of the nitride semiconductor on the M-plane, see, for example,
The details are described in JP-A-232676.

[0036]

EXAMPLE An example of a nitride semiconductor laser device according to an embodiment of the present invention will be described below. However, the present invention is not limited to this. [Embodiment 1] FIG. 3 is a schematic sectional view showing the structure of a laser device according to an embodiment of the present invention, and is a view when cut in a direction perpendicular to a stripe waveguide. Hereinafter, the first embodiment will be described with reference to FIG.

(Underlayer 2) A heterogeneous substrate 1 made of sapphire having a 1-inch φ, C-plane as a main surface is set in a MOVPE reaction vessel, the temperature is set to 500 ° C., and trimethyl gallium (TMG), ammonia (NH 3) ₃ ) Using GaN
A buffer layer is grown to a thickness of 200 Å. After the growth of the buffer layer, the temperature is raised to 1050 ° C., and an underlayer 2 also made of GaN is grown to a thickness of 4 μm. This underlayer forms a protective film partially on the surface and then acts as an underlayer for selectively growing a nitride semiconductor substrate.

(Protective film 3) After growth of the underlayer, the wafer is taken out of the reaction vessel, a stripe-shaped photomask is formed on the surface of the underlayer, and a stripe width of 10 μm and a stripe interval (window) of 2 μm are formed by a PVD apparatus. SiO
_A protective film 3 of ₂ is formed.

(Nitride Semiconductor Substrate 4) After the formation of the protective film, the wafer is set again in the MOVPE reaction vessel, the temperature is set to 1050 ° C., and the nitride semiconductor substrate 4 made of undoped GaN using TMG and ammonia is removed. It is grown to a thickness of 20 μm. Since this nitride semiconductor substrate is grown laterally above the protective film 3, the number of crystal defects is 10 ⁵ / cm ² or less, which is two orders of magnitude less than that of the underlayer 2.

(N-side contact layer 5) Next, using ammonia, TMG, and silane gas as an impurity gas, Si was placed on the nitride semiconductor substrate 1 at 1050 ° C. at 3 × 10 ^18/3 .
n-side contact layer 5 made of GaN doped with cm ³
It is grown to a thickness of μm.

(Crack prevention layer 6) Next, TMG, TM
Using I (trimethylindium) and ammonia at a temperature of 800 ° C., a crack prevention layer 6 of In _0.06 Ga _0.94 N is grown to a thickness of 0.15 μm. The crack prevention layer can be omitted.

(N-side cladding layer 7) Subsequently, at 1050 ° C.
Using TMA (trimethylaluminum), TMG, and ammonia, a layer made of undoped Al _0.16 Ga _0.84 N is grown to a thickness of 25 angstroms.
A was stopped, silane gas was flowed, and Si was reduced to 1 × 10 ¹⁹ / cm
^A layer of ^3- doped n-type GaN is grown to a thickness of 25 Å. These layers are alternately laminated to form a superlattice layer, and a superlattice having a total thickness of 1.2 μm
The side cladding layer 7 is grown.

(N-side light guide layer 8) Subsequently, the silane gas is stopped and the n-side light guide layer 8 made of undoped GaN is grown at 1050 ° C. to a thickness of 0.1 μm. The n-side light guide layer 8 may be doped with an n-type impurity.

(Active Layer 9) Next, the temperature was set to 800 ° C., and a barrier layer made of Si-doped In _0.05 Ga _0.95 N was formed.
Then, at the same temperature, a well layer made of undoped In _0.2 Ga _0.8 N was formed in a thickness of 4 Å.
It is grown to a thickness of 0 Å. A barrier layer and a well layer are alternately stacked twice, and finally a barrier layer is completed, and a multiple quantum well structure (MQ) having a total thickness of 380 Å is formed.
The active layer of W) is grown.

(P-side cap layer 10)
Raise to 50 ° C, TMG, TMA, ammonia, Cp2M
g (cyclopentadienyl magnesium), p-type Al _0.3 Ga doped with Mg at 1 × 10 ²⁰ / cm ³ and having a larger band gap energy than the p-side light guide layer 11
_A p-side cap layer 7 of _0.7 N is grown to a thickness of 300 Å.

(P-side light guide layer 11) Subsequently, Cp2M
g, TMA is stopped, and at 1050 ° C., a p-side optical guide layer 11 of undoped GaN having a band gap energy smaller than that of the p-side cap layer 10 is grown to a thickness of 0.1 μm.

(P-side cladding layer 12)
A layer of undoped Al _0.16 Ga _0.84 N is grown at 25 ° C. to a thickness of 25 Å, followed by Cp ₂ Mg,
The TMA is stopped, a layer made of undoped GaN is grown to a thickness of 25 Å, and a p-side cladding layer 12 made of a superlattice layer having a total thickness of 0.6 μm is grown.

(P-side contact layer 13) Finally, 105
At 0 ° C., Mg was added to the p-side cladding layer 9 at 1 × 10 ²⁰ /
p-side contact layer 1 made of p-type GaN doped with cm ³
3 is grown to a thickness of 150 angstroms.

The wafer on which the nitride semiconductor has been grown as described above is taken out of the reaction vessel, and a protective film made of SiO ₂ is formed on the surface of the uppermost p-side contact layer.
Etching is performed by SiCl ₄ gas using RIE (reactive ion etching) to expose the surface of the n-side contact layer 5 on which the n-electrode is to be formed, as shown in FIG. In order to deeply etch the nitride semiconductor in this way, SiO ₂ is optimal as a protective film.

Next, as shown in FIG. 6A, a first protective film 61 made of Si oxide (mainly SiO ₂ ) is formed on almost the entire surface of the uppermost p-side contact layer 13 by a PVD apparatus. Is formed in a thickness of 0.5 μm, a mask having a predetermined shape is applied on the first protective film 61, and a third protective film 63 made of photoresist is formed with a stripe width of 2 μm.
m and a thickness of 1 μm.

Next, as shown in FIG. 6B, after forming the third protective film 63, an RIE (Reactive Ion Etching) device is used, using CF ₄ gas and using the third protective film 63 as a mask. The first protective film 61 is etched into a stripe shape. Thereafter, the photoresist is removed by treating with an etchant, thereby forming a stripe width of 2 μm on the p-side contact layer 13 as shown in FIG.
The first protective film 61 can be formed.

Further, as shown in FIG. 6D, after the stripe-shaped first protective film 61 is formed, S is formed again by RIE.
Using iCl ₄ gas, the p-side contact layer 13 and the p-side cladding layer 12 are etched to form a stripe-shaped waveguide region (ridge stripe in this case). When a stripe is formed, it is highly preferable that the cross-sectional shape of the stripe be a forward mesa shape as shown in FIG.

After forming the ridge stripe, the wafer is
6E, a _second protective film 62 made of a Zr oxide (mainly ZrO ₂ ) is formed on the first protective film 61 and the p exposed by the etching as shown in FIG.
It is formed continuously on the side cladding layer 12 with a thickness of 0.5 μm.

Next, the wafer is immersed in hydrofluoric acid,
As shown in (f), the first protective film 61 is removed by a lift-off method.

Next, as shown in FIG. 6 (g), the first protective film 61 on the p-side contact layer 13 is removed and the exposed surface of the p-side contact layer is made of Ni / Au.
An electrode 20 is formed. However, the p-electrode 20 has a stripe width of 100 μm, and as shown in FIG.
Over the protective film 62 of FIG.

After the formation of the p-electrode 20, FIG. 3 and FIG.
As shown in FIG. _TwoInsulation consisting of
A protective film 201 having a thickness of 0.1 μm
It is formed by sputtering film formation.

Next, a first thin film layer 31 made of Ti is formed to a thickness of 1000 Å continuously on the entire surface of the exposed p-electrode 20 not covered with the insulating protective film 201. Further, as shown in FIG. 3, a first thin film layer 31 is formed on the side surface of the stripe and the like. On the first thin film layer 31 formed continuously, the first thin film layer 31 has a size that does not match the cleavage plane when the resonance plane is formed by cleavage in a later step, that is, the first thin film layer 31 is intermittently avoiding the upper part of the cleavage plane. A second thin film layer 32 made of Au is formed to a thickness of 8000 angstroms, and a p pad electrode 101 made of the first thin film layer 31 and the second thin film layer 32 is formed.

After the formation of the p-pad electrode, the surface of the n-side contact layer 5 exposed first is formed of n
The electrode 21 is formed in a direction parallel to the stripe, and an n pad electrode made of Ti / Pt / Au is formed thereon.

As described above, the n-electrode, p-electrode and p-electrode
After polishing the sapphire substrate of the wafer having the pad electrodes formed thereon to 70 μm, the wafer is cleaved in a bar shape from the substrate side in a direction perpendicular to the striped electrodes, and the cleavage plane (11-0)
(0 plane, plane corresponding to the side surface of hexagonal columnar crystal = M plane). A dielectric multilayer film composed of SiO ₂ and TiO ₂ is formed on the resonator surface, and finally, in a direction parallel to the p-electrode,
The bar is cut to obtain a laser device as shown in FIG. The resonator length is desirably 300 to 500 μm.

This laser element is placed on a heat sink,
When each electrode was wire-bonded and laser oscillation was attempted at room temperature, the oscillation wavelength was 400 to 420 n.
m, good continuous oscillation at room temperature at a threshold current density of 2.9 kA / cm ² . Furthermore, even if the resonance surface is formed by cleavage, peeling of the p-electrode can be prevented, element deterioration due to peeling of the electrode is significantly reduced, heat dissipation is improved, and a laser element having good life characteristics can be efficiently manufactured. it can.

Example 2 A laser device was fabricated in the same manner as in Example 1, except that the insulating protective film 201 was continuously formed up to the p-electrode portion above the cleavage plane as shown in FIG. I do. The obtained laser device shows good device characteristics as in Example 1, and the prevention of peeling of the p-electrode is slightly better than in Example 1.

[Embodiment 3] FIG. 4 is a schematic sectional view showing the structure of a laser device according to another embodiment of the present invention. Hereinafter, Embodiment 3 will be described with reference to FIG.

(Nitride Semiconductor Substrate 40) In the first embodiment, after forming the stripe-shaped protective film 3 on the surface of the underlayer 2,
The wafer is set again in the MOVPE reaction vessel, the temperature is set to 1050 ° C., and undoped GaN is grown to a thickness of 5 μm using TMG and ammonia. afterwards,
The wafer is transferred to an HVPE (hydride vapor phase epitaxy) apparatus, and a nitride semiconductor substrate 40 made of undoped GaN is grown to a thickness of 200 μm using Ga metal, HCl gas and ammonia as raw materials. In this way MO
After a nitride semiconductor is grown on the protective film 3 by the VPE method and then a GaN thick film of 100 μm or more is grown by the HVPE method, the crystal defects are reduced by one digit or more compared to the first embodiment. After the growth of the nitride semiconductor substrate 40, the wafer is taken out of the reaction vessel, and the sapphire substrate 1, the buffer layer 2, the protective film 3, and the undoped GaN layer are removed by polishing, so that the nitride semiconductor substrate 40 is used alone.

Thereafter, in the same manner as in Example 1, the n-side contact layers 5 to 5 are formed on the nitride semiconductor substrate 40 on the side opposite to the polishing side.
The layers up to the p-side contact layer 13 are stacked.

After the growth of the p-side contact layer 13, a striped first protective film 61 is formed in the same manner as in the first embodiment, and then, in the second step, an etching stop is made on the surface of the n-side contact layer 5. I do. Thereafter, in the same manner as in Example 1, a second protective film 62 containing ZrO ₂ as a main component is formed on the side surface of the stripe waveguide and the surface of the n-side contact layer 5, and an electrode is formed on each contact layer. On the formed and formed p-electrode, as shown in FIG.
₂ ) An insulating protective film made of ₂ ) is formed with a thickness of 0.1 μm. Next, a p-pad electrode 101 is formed in the same manner as in the first embodiment to obtain a laser device having a structure as shown in FIG. In the case where a resonance surface is formed, the cleavage plane of the nitride semiconductor substrate is the same M plane as in the first embodiment. Example 1
, The threshold current density is reduced to 1.8 kA / cm ² , the service life is improved three times or more, and the peeling of the p-electrode can be prevented well as in the first embodiment.

[Embodiment 4] FIG. 5 is a schematic sectional view showing the structure of a laser device according to another embodiment of the present invention. Embodiment 4 will be described below with reference to FIG.

In the third embodiment, the nitride semiconductor substrate 40
A silane gas is added to the raw material in the HVPE apparatus to produce a nitride semiconductor substrate 50 made of GaN doped with 1 × 10 ¹⁸ / cm ^{3 of} Si with a thickness of 200 μm. The Si concentration is 1 × 10 ¹⁷ / cm ^{3 to} 5 × 10 ¹⁹ / c
It is preferably in the range of m ^3. Nitride semiconductor substrate 50
After the growth, the sapphire substrate 1, the buffer layer 2, the protective film 3, and the undoped GaN layer are polished and removed in the same manner as in Example 3 to obtain the nitride semiconductor substrate 50 alone.

Next, on the nitride semiconductor substrate 50, a layer from the crack preventing layer 6 to the p-side contact layer 13 is grown in the same manner as in the first embodiment. After the growth of the p-side contact layer 13, a stripe-shaped first protective film 61 is formed in the same manner as in the first embodiment. In the second step, an etching stop is performed on the surface of the n-side cladding layer 7 shown in FIG. And Thereafter, in the same manner as in the embodiment, after forming the second protective film 62 mainly composed of ZrO ₂ on the side surface of the stripe waveguide and the surface of the n-side cladding layer 7, the second protective film is formed. A p-electrode 20 is formed through the interposition. After the formation of the p-electrode, an insulating protective film 201 made of a Si oxide film (SiO ₂ ) is formed to a thickness of 0.1 μm by sputtering as shown in FIGS.

After the formation of the insulating protective film, a first thin film layer 31 made of Ti is formed on the insulating protective film and the p-electrode 21 so as to have a thickness of 1000 Å so as to have the same length as the stripe length. A third thin film layer made of Pt having a shape similar to that of the thin film layer 32 of the above is laminated in order with a thickness of 1000 Å, and a second thin film layer 32 made of Au having a shape shorter than the stripe length is formed in a thickness of 8000 Å. The formed p-pad electrode 101 is formed as shown in FIG. Although the third thin film layer is not shown,
It is formed in the same shape as the second thin film layer. On the other hand, an n-electrode 21 is formed on substantially the entire back surface of the nitride semiconductor substrate.
After the formation of the electrodes, cleavage was performed on the M-plane of the nitride semiconductor substrate to form a resonance surface, and a laser element having a structure as shown in FIG. 5 was obtained. A laser element having substantially the same characteristics as described above can be obtained.

[Embodiment 5] J. A. P. The laser device of FIG. 7 showing the laser device described in FIG.
As shown in FIG. 2A, a Si oxide film (SiO ₂ )
A laser element is manufactured in the same manner except that an insulating protective film made of is formed to a thickness of 0.1 μm. As a result, when the resonance surface is formed by cleavage, peeling of the p-electrode can be prevented well, heat dissipation can be improved, and a laser device having good device characteristics with good productivity can be obtained.

[0071]

According to the present invention, in order to further improve the practicality, even if the resonance surface is formed by cleavage, peeling of the p-electrode is prevented, and the nitride semiconductor having high productivity, high reliability and good life characteristics is provided. A laser device can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a part of a nitride semiconductor laser device according to one embodiment of the present invention.

FIG. 2 is a schematic plan view showing a part of the nitride semiconductor laser device according to one embodiment shown in FIG.

FIG. 3 is a schematic sectional view of a nitride semiconductor laser device according to one embodiment of the present invention.

FIG. 4 is a schematic sectional view of a nitride semiconductor laser device according to one embodiment of the present invention.

FIG. 5 is a schematic sectional view of a nitride semiconductor laser device according to one embodiment of the present invention.

FIG. 6 is a schematic cross-sectional view showing a partial structure of a wafer in each step for explaining each step of a method for forming a ridge-shaped stripe or the like in FIGS. 3 to 5;

FIG. 7 is a schematic sectional view showing the structure of a conventional laser device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Different substrate 2 ... Underlayer 3 ... Protective film for nitride semiconductor substrate growth 4, 40, 50 ... Nitride semiconductor substrate 5 ... n-side contact layer 6 ... Crack Prevention layer 7 ... n-side cladding layer 8 ... n-side light guide layer 9 ... active layer 10 ... p-side cap layer 11 ... p-side light guide layer 12 ... p-side cladding layer 13 ... p-side contact layer 61 ... first protective film 62 ... second protective film 63 ... third protective film 20 ... p electrode 21 ... n electrode 31 ... 1st thin film layer 32 ... 2nd thin film layer 101 ... pad electrode 201 ... insulating protective film

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[Procedure amendment]

[Submission date] November 12, 1999 (1999.11.
12)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction contents]

[0005]

That is, the object of the present invention is to
This can be achieved by the following configurations (1) to (5) . (1) Ridge-shaped struts having a width of 0.5 to 4.0 μm
Ip and the side and ridge of the ridge-shaped stripe
P-type or n-type continuous from the side of the shaped stripe
A first insulating film formed on an exposed surface of
From the entire surface of the uppermost layer of the stripe
Of the first insulating film formed on the side surface of the stripe
A p-electrode formed continuously up to the surface of the portion;
Partial surface of p-electrode formed on first insulating film
From above, one of the first insulating films not covered with the p-electrode
Second insulating film formed continuously up to the surface of the portion
Electrically contacting the p-electrode, and further comprising the second insulating
A p-pad electrode formed to be in contact with the edge film;
In the direction perpendicular to the length of the stripe
And a resonance surface formed by opening.
Nitride semiconductor laser device. (2) The first insulating film is made of an oxide of Zr or an acid of Hf
BN or SiC
The nitride semiconductor laser element according to the above (1), wherein
Child. (3) The second insulating film is made of SiO ₂ , TiO ₂ and A
The nitride semiconductor laser device according to (1), wherein the nitride semiconductor laser device is at least one of l ₂ O ₃ . (4) The second insulating film is formed so as to cover at least a part of both sides of a p-electrode formed on the first insulating film in parallel with a ridge-shaped stripe length direction. The nitride semiconductor laser device according to the above (1). (5) The method according to (4), wherein the second insulating film formed on a part of both sides of the p-electrode is continuously formed up to a part of the p-electrode above the cleavage plane. Nitride semiconductor laser device.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction contents]

That is, according to the present invention, by covering a portion of the p-electrode from the part of the p-electrode to the side surface of the ridge with the second insulating film , the separation of the p-electrode due to cleavage is prevented, the heat dissipation is improved, and the reliability and the life are improved. A nitride semiconductor laser device having good characteristics can be provided. Furthermore, productivity is improved by the above configuration. It is considered that the improvement in heat dissipation due to the prevention of the separation of the p-electrode is due to the efficient conduction of heat from the p-electrode to the p-pad electrode. Also,
Since the second insulating film of the present invention is further formed on the first insulating film on the side surface of the ridge-shaped stripe, the insulating property of the laser element is reinforced, and the reliability of the laser element is improved ( (Prevention of defects). In the present invention, p
From a part of the electrode to the side of the ridge-shaped stripe
To form the second insulating film means to cover a part of the p-electrode and to cover a portion other than the p-electrode in the side direction of the ridge-shaped stripe, for example, the first insulating film , the side surface of the p-side nitride semiconductor layer, or the substrate. And so on.
The second insulating film has a function of pressing down the p-electrode and preventing the ridge-shaped stripe from peeling off from the uppermost p-side nitride semiconductor layer. According to the present invention, by disposing the second insulating film as described above, various characteristics of the laser element are not adversely affected, and the manufacturing process can be simply and efficiently performed. It was done.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction contents]

As described above, the necessity of adding the function of preventing the p-electrode formed on the upper part of the ridge-shaped stripe from being peeled off to the laser element is considered to be the practicality that enables the present inventors to perform continuous oscillation for a long time. The realization of a laser device with a high level of operation has led to severe operating conditions, and it has become necessary to overcome the slight inadequacies in previously unforeseen parts in order to commercialize the laser device. . In order to cope with such a need, the present invention sets the second insulating film as described above in order to reduce the possibility that device deterioration is likely to be caused during operation of the laser device due to slight peeling due to cleavage of the p-electrode. It is improved by forming.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction contents]

In the present invention, when the second insulating film is formed so as to cover at least a part of both sides of the p-electrode in parallel with the ridge-shaped stripe length direction, it is possible to prevent the p-electrode from peeling. preferable. In the present invention, the second insulating film formed on a part of both sides of the p-electrode is formed continuously up to a part of the p-electrode formed on the cleavage plane and on the ridge-shaped stripe. In this case, it is possible to increase the adhesion of the p-electrode above the cleavage plane where a physical force is likely to be applied when cleaving, and it is possible to more favorably prevent the p-electrode from peeling off. Here, when the second insulating film is formed near the cleavage plane of the p-electrode formed on the ridge-shaped stripe, the thermal conductivity of the second insulating film is inferior to that of the p-electrode. It is desirable to form a second insulating film from the viewpoint of heat dissipation so that the contact of the p-pad electrode having the function of dissipating the heat with the p-electrode is not hindered as much as possible. Further, in the present invention, the second insulating film is made of S
When at least one of TiO ₂ , TiO _2, and Al ₂ O ₃ is used, peeling of the p-electrode can be favorably prevented, which is preferable in terms of insulating properties, and is further preferable in terms of line stability by simplifying the process. .

[Procedure amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction contents]

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A nitride semiconductor laser device according to the present invention has a p-electrode in the uppermost layer of a ridge-shaped stripe having a first insulating film on the side surface of the stripe, and extends in the length direction of the ridge-shaped stripe. A cleavage surface formed by cleavage in a direction perpendicular to the surface, a resonance surface, and a second insulating film is formed from a portion of the p-electrode to a side surface of the ridge-shaped stripe; On this, a p-pad electrode formed electrically connected to the p-electrode is provided. The second insulating film in the present invention, before forming the p-pad electrode, for physical p electrode even when a force is suffering, such as cleavage is prevented from peeling from the uppermost layer of the stripe ridge, p
The electrode is formed from the p-electrode to a portion other than the p-electrode so as to press down a part of the electrode, for example, over the ridge-shaped stripe side surface.

[Procedure amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction contents]

FIG. 1 shows an embodiment of the present invention.
The present invention will be described in detail with reference to FIG. Figure 1 shows the second insulation
FIG. 4 is a schematic cross-sectional view showing a part of the nitride semiconductor laser device according to one embodiment in which a film 201 is formed, which is cut perpendicularly to a length direction of a ridge-shaped stripe. FIG. 1 shows a p-electrode 20 on the uppermost p-side contact layer 13 of a ridge-shaped stripe having a first insulating film 62 on a side surface.
Is formed, and on the p-electrode 20, as shown in FIG.
A nitride semiconductor laser device in which a second insulating film 201 is formed from both sides of the p-electrode 20 to the side of the ridge-shaped stripe, and a p-pad electrode is formed thereon so as to be electrically connected to the p-electrode. Is shown. Further, FIG. 2 is a schematic plan view showing a part of the nitride semiconductor laser device in a state where the p-pad electrode is not formed in the schematic sectional view of FIG. 1 when a side having a ridge-shaped stripe is viewed from directly above. The figure is shown. The dotted line near the center of FIG.
The position of the ridge-shaped stripe that does not appear on the surface due to the formation of the electrode is shown. The two-dot chain line indicates the formation position of the p-electrode, and the second insulating film formed on the p-electrode. The portion of the p-electrode that is covered with and does not appear on the surface is shown. Further, R in FIG. 2 indicates a ridge-shaped stripe width, and P indicates a width when the p-electrode is viewed from above.

[Procedure amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction contents]

In the present invention, the second insulating film 201 is
The ridge-shaped stripe may be formed so as to cover at least a part of the p-electrode and to extend to the side surface of the ridge-shaped stripe. Preferably, as shown in FIGS. 1 and 2A, both sides of the p-electrode are partially covered. It is formed so as to be parallel to the length direction. Further, as shown in FIG. 2B, a second insulating film 201 covering both sides of the p-electrode is continuous and comes into contact with the uppermost p-side contact layer 13 of the ridge-shaped stripe above the cleavage plane. If the second insulating film 201 on the upper part of the cleavage plane is apt to be subjected to an impact at the time of cleavage when the second insulating film 201 is formed continuously on the p electrode that has been formed [upper part of the cleavage plane having the ridge width R shown in FIG. 2B]. Since the end portions of the p-electrodes 20 are pressed, peeling of the p-electrode is preferably prevented, which is preferable.

[Procedure amendment 9]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction contents]

In the present invention, as the second insulating film ,
The material is not particularly limited as long as it has an insulating property, and is preferably a material having an insulating property and an adhesive force with an insulating film or the like constituting a laser element to such an extent that the p-electrode can be prevented from peeling off. And more preferably an insulating oxide. For example, specifically, SiO ₂ , TiO ₂ , Al ₂ O ₃ , Si
Examples of the material include any one or more of N and TaO _X , and preferably SiO ₂ , TiO ₂ , and A
Examples of the material include at least one of l ₂ O ₃ . Use of such a material is preferable for preventing peeling of the p-electrode. Further, the second insulating film can reinforce the insulating property on the side surface of the ridge-shaped stripe of the laser element, and is also preferable in terms of improving the reliability (prevention of failure) of the laser element. Although the thickness of the second insulating film is not particularly limited,
For example, specifically, it is 0.01-1 μm, preferably 0.1-0.5 μm, more preferably 0.1 μm
Film thickness of the order. It is preferable that the thickness of the second insulating film be in the above range in order to prevent peeling of the p-electrode. The formation of the second insulating film in consideration of the strength of adhesion to a portion of the laser device made of the material of the second insulating film , for example, the first insulating film, etc., and the thermal conductivity. The form, film thickness and the like to be formed are adjusted.

[Procedure amendment 10]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction contents]

In the present invention, as a method of forming the second insulating film , a film is formed on a pattern by photolithography using a sputtering film forming method, and the insulating film is formed only on a portion to be formed.

[Procedure amendment 11]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction contents]

The first pump used in the laser device of the present invention
The edge film 62 is not particularly limited, but may be, for example, SiO 2 used in FIG. 7 showing a conventional laser device.
₂ and Ti, V, Zr used as a second protective film (insulating film) preferable for forming a nitride semiconductor laser device having a stripe structure having a stripe width of 0.5 to 4.0 μm, which will be described later. , Nb, Hf, an oxide containing at least one element selected from the group consisting of Ta, BN,
SiC and AlN are mentioned. In addition, a Si oxide can be used as a second protective film described later. In this case, a material that is more easily etched than the Si oxide is selected as a material for the first protective film described later.

[Procedure amendment 12]

[Document name to be amended] Statement

[Correction target item name] 0056

[Correction method] Change

[Correction contents]

After the formation of the p-electrode 20, FIG. 3 and FIG.
As shown in FIG. _TwoConsisting ofSecond
Insulating film201 is formed on the p-electrode 20 with a thickness of 0.1 μm.
It is formed by sputtering film formation.

[Procedure amendment 13]

[Document name to be amended] Statement

[Correction target item name] 0057

[Correction method] Change

[Correction contents]

Next, a first thin film layer 31 made of Ti is formed to a thickness of 1000 Å continuously on the entire surface of the exposed p-electrode 20 not covered with the second insulating film 201. Then, as shown in FIG. 3, a first thin film layer 31 is also formed on the side surface of the stripe and the like. On the first thin film layer 31 formed continuously, the first thin film layer 31 has a size that does not match the cleavage plane when the resonance plane is formed by cleavage in a later step, that is, the first thin film layer 31 is intermittently avoiding the upper part of the cleavage plane. A second thin film layer 32 made of Au is formed to a thickness of 8000 angstroms, and a p pad electrode 101 made of the first thin film layer 31 and the second thin film layer 32 is formed.

[Procedure amendment 14]

[Document name to be amended] Statement

[Correction target item name] 0061

[Correction method] Change

[Correction contents]

[Embodiment 2] In Embodiment 1, the second absolute
A laser element is manufactured in the same manner except that the edge film 201 is continuously formed up to the p-electrode portion above the cleavage plane as shown in FIG. The obtained laser device shows good device characteristics as in Example 1, and the prevention of peeling of the p-electrode is slightly better than in Example 1.

[Procedure amendment 15]

[Document name to be amended] Statement

[Correction target item name] 0065

[Correction method] Change

[Correction contents]

After the growth of the p-side contact layer 13, a striped first protective film 61 is formed in the same manner as in the first embodiment. In the second step, an etching stop is made on the surface of the n-side contact layer 5. I do. Thereafter, in the same manner as in Example 1, a second protective film 62 containing ZrO ₂ as a main component is formed on the side surface of the stripe waveguide and on the surface of the n-side contact layer 5, and an electrode is formed on each contact layer. As shown in FIG. 4, an Si oxide film (SiO 2
₂ ) A second insulating film having a thickness of 0.1 μm is formed. Next, a p-pad electrode 101 is formed in the same manner as in the first embodiment to obtain a laser device having a structure as shown in FIG. When forming a resonance plane, the cleavage plane of the nitride semiconductor substrate is the same M plane as in the first embodiment. The obtained laser device is the same as in Example 1.
, The threshold current density is reduced to 1.8 kA / cm ² , the service life is improved three times or more, and the peeling of the p-electrode can be prevented well as in the first embodiment.

[Procedure amendment 16]

[Document name to be amended] Statement

[Correction target item name]

[Correction method] Change

[Correction contents]

Next, on the nitride semiconductor substrate 50, a layer from the crack preventing layer 6 to the p-side contact layer 13 is grown in the same manner as in the first embodiment. After the growth of the p-side contact layer 13, a stripe-shaped first protective film 61 is formed in the same manner as in the first embodiment. In the second step, an etching stop is performed on the surface of the n-side cladding layer 7 shown in FIG. And Thereafter, in the same manner as in the embodiment, after forming the second protective film 62 mainly composed of ZrO ₂ on the side surface of the stripe waveguide and the surface of the n-side cladding layer 7, the second protective film is formed. A p-electrode 20 is formed through the interposition. After the formation of the p-electrode, as shown in FIGS. 5 and 2A, a second insulating film 201 made of a Si oxide film (SiO ₂ ) is formed to a thickness of 0.1 μm by sputtering.

[Procedure amendment 17]

[Document name to be amended] Statement

[Correction target item name] 0069

[Correction method] Change

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[0069] After forming the second insulating film, over the second insulating film and the p-electrode 21, a first thin film layer 31 made of Ti so that the stripe length the same length and a thickness of 1000 Å, A third thin film layer made of Pt and having a thickness similar to that of the second thin film layer 32 and having a thickness of 1000 angstroms, and a second thin film layer 32 made of Au and having a shape shorter than the stripe length having a thickness of 8000 angstroms. A p-pad electrode 101 is formed as shown in FIG. Although the third thin film layer is not shown,
It is formed in the same shape as the second thin film layer. On the other hand, an n-electrode 21 is formed on substantially the entire back surface of the nitride semiconductor substrate.
After the formation of the electrodes, cleavage was performed on the M-plane of the nitride semiconductor substrate to form a resonance surface, and a laser element having a structure as shown in FIG. 5 was obtained. A laser element having substantially the same characteristics as described above can be obtained.

[Procedure amendment 18]

[Document name to be amended] Statement

[Correction target item name] 0070

[Correction method] Change

[Correction contents]

[Embodiment 5] J. A. P. The laser device of FIG. 7 showing the laser device described in FIG.
As shown in FIG. 2A, a Si oxide film (SiO ₂ )
A laser device is manufactured in the same manner except that a second insulating film made of is formed to a thickness of 0.1 μm. As a result, when the resonance surface is formed by cleavage, peeling of the p-electrode can be favorably prevented, heat dissipation can be improved, and a laser device having good device characteristics with good productivity can be obtained.

[Procedure amendment 19]

[Document name to be amended] Statement

[Correction target item name] Explanation of sign

[Correction method] Change

[Correction contents]

[Description of Reference Numerals] 1 ... heterogeneous substrate 2 ... underlayer 3 ... protective film for growing nitride semiconductor substrate 4, 40, 50 ... nitride semiconductor substrate 5 ... n-side contact layer 6 crack preventing layer 7 n-side cladding layer 8 n-side light guide layer 9 active layer 10 p-side cap layer 11 p-side light guide layer 12 · P-side cladding layer 13 ··· p-side contact layer 61 ··· first protection film 62 ··· second protection film (first insulating film) 63 ··· third protection film 20 ··· -P electrode 21 ... n electrode 31 ... first thin film layer 32 ... second thin film layer 101 ... pad electrode 201 ... second insulating film

Claims (4)

[Claims] 1. A ridge-shaped stripe having an insulating film on a side surface of the stripe, a p-electrode on an uppermost layer of the stripe, and cleavage in a direction perpendicular to a length direction of the ridge-shaped stripe. A nitride semiconductor laser device having a resonance surface on a formed cleavage plane, comprising: an insulating protective film formed from a part of the p-electrode to a side surface of a ridge-shaped stripe; A nitride semiconductor laser device having a p-pad electrode formed by electrical connection. 2. The nitride according to claim 1, wherein the insulating protective film is formed so as to cover at least a part of both sides of the p-electrode in parallel with a ridge-shaped stripe length direction. Semiconductor laser device. 3. The p-electrode according to claim 2, wherein the insulating protective films formed on portions on both sides of the p-electrode are continuously formed up to a portion of the p-electrode above the cleavage plane. Nitride semiconductor laser device. 4. The insulating protective film is made of SiO ₂ , TiO ₂
And nitride semiconductor laser device according to any one of claims 1 to 3, wherein the Al is ₂ O ₃ of any one or more.