JP2006013331A - Semiconductor laser element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor laser element, wherein deterioration of element characteristics and deterioration of element lifetime are controlled, while restraining lifting of a pad electrode and an ohmic electrode, while the increase in the operating voltage of the element can be restrained. <P>SOLUTION: The semiconductor laser element is provided with a p-type cladding layer 6 and a contact layer 7, which are formed on an active layer 3 and constitute a protruded ridge 8; the p-side ohmic electrode 9 formed on the ridge 8; a current block layer 10 which is formed on the p-type clad layer 6 formed at least on the part of the side surface of the ridge 8; a Ti layer 11 which is formed on the current block layer 10, in contact with the surface of the current block layer 10; and the p-side pad electrode 12 which is in contact with surfaces of the p-side ohmic electrode 9 and the Ti layer 11. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a semiconductor laser device, and more particularly to a semiconductor laser device having a light emitting layer.

  2. Description of the Related Art Conventionally, a semiconductor laser element in which semiconductor layers including a light emitting layer are formed on a substrate is known (see, for example, Patent Document 1).

  FIG. 33 is a cross-sectional view showing the structure of a conventional semiconductor laser device. Referring to FIG. 33, in a conventional semiconductor laser element, an n-type cladding layer 102, a light emitting layer 103, and a p-type cladding layer 104 are sequentially formed on a sapphire substrate 101. The p-type cladding layer 104 has a convex part and a flat part other than the convex part. A p-type contact layer 105 is formed on the convex portion of the p-type cladding layer 104. The p-type contact layer 105 and the convex portion of the p-type cladding layer 104 constitute a ridge portion 106. Further, by removing a predetermined region from the surface of the flat portion of the p-type cladding layer 104 to a depth in the middle of the n-type cladding layer 102, a part of the surface of the n-type cladding layer 102 is exposed. The n-type cladding layer 102, the light emitting layer 103, the p-type cladding layer 104, and the p-type contact layer 105 are made of a nitride-based semiconductor layer.

On the p-type contact layer 105 constituting the ridge portion 106, a p-side ohmic electrode 107 composed of a lower Ni layer and an upper Pt layer is formed. On the p-type cladding layer 104, a current blocking layer 108 made of a SiO ₂ layer having an opening 108a in a region corresponding to the upper surface of the p-side ohmic electrode 107 is formed. A p-side pad electrode 109 is formed on the current blocking layer 108 so as to be in contact with the upper surface of the p-side ohmic electrode 107 through the opening 108a. The p-side pad electrode 109 is composed of a Ti layer, a Pt layer, and an Au layer from the lower layer to the upper layer. That is, the lowermost Ti layer constituting the p-side pad electrode 109 is in contact with the surfaces of the current blocking layer 108 and the p-side ohmic electrode 107. An n-side electrode 110 is formed on the exposed surface of the n-type cladding layer 102.

Here, the lowermost Ti layer constituting the p-side pad electrode 109, adhesion to the SiO ₂ layer constituting the current blocking layer 108 is known to stronger (e.g., see Non-Patent Document 1). For this reason, in the conventional semiconductor laser device shown in FIG. 33, it is possible to prevent the p-side pad electrode 109 from peeling from the current blocking layer 108. Further, since the p-side pad electrode 109 can be prevented from being peeled off from the current blocking layer 108, the p-side ohmic electrode 107 whose upper surface is in contact with the p-side pad electrode 109 is connected to the p-type contact together with the p-side pad electrode 109. It is possible to suppress peeling from the layer 105.
JP 2000-299528 A Masao Masashita, Masaji Yoshida, “Thin Film Engineering Handbook” Kodansha, October 20, 1998, p. 386

However, since the lowermost Ti layer constituting the p-side pad electrode 109 of the conventional semiconductor laser device shown in FIG. 33 has a low thermal conductivity (about 0.22 W / (cm · K)), a high output operation is achieved. When heat generated in the light emitting layer 103 is sometimes transmitted to the p-side ohmic electrode 107, it is difficult to sufficiently dissipate heat at the p-side pad electrode 109 that contacts the upper surface of the p-side ohmic electrode 107. As a result, the heat dissipation characteristics are deteriorated, so that the element characteristics are deteriorated and the element life is shortened. Further, since the lowermost Ti layer constituting the p-side pad electrode 109 has a high electric resistivity (about 39.0 × 10 ⁻⁸ Ω · m), the p-side ohmic electrode 107 is interposed via the p-side pad electrode 109. There is an inconvenience that the resistance to the current injected into the capacitor becomes high. This also has the disadvantage that the operating voltage of the element increases. Therefore, in the conventional semiconductor laser element shown in FIG. 33, even if the separation of the p-side pad electrode 109 from the current blocking layer 108 is suppressed, the element characteristics are deteriorated, the element lifetime is reduced, and the element There is a problem that the operating voltage increases.

  The present invention has been made to solve the above-described problems, and one object of the present invention is to reduce element characteristics and device lifetime while suppressing the peeling of the pad electrode and ohmic electrode. It is an object of the present invention to provide a semiconductor laser device that can suppress and increase the operating voltage of the device.

Means for Solving the Problems and Effects of the Invention

  In order to achieve the above object, a semiconductor laser device according to one aspect of the present invention includes a semiconductor layer formed on a light emitting layer and having a convex ridge portion, and an ohmic electrode formed on the ridge portion of the semiconductor layer. And an insulating layer formed on the semiconductor layer and formed on at least a part of the side surface of the ridge portion, and an adhesion layer formed on the insulating layer and including at least one of a metal and a semiconductor contacting the surface of the insulating layer And a pad electrode in contact with the surface of the ohmic electrode and the adhesion layer.

  In the semiconductor laser device according to the one aspect, as described above, the adhesion layer is formed so as to be in contact with the surface of the insulating layer, and the pad electrode is brought into contact with the surface of the adhesion layer, whereby the adhesion layer is formed into the insulating layer. If the material is made of a material having a strong adhesion force to the insulating layer, the adhesion layer can be prevented from peeling off from the insulating layer. Thereby, it can suppress that the pad electrode which contacts the surface of an adhesion layer peels with an adhesion layer. In addition, since the peeling of the pad electrode can be suppressed, the ohmic electrode whose surface is in contact with the pad electrode can be prevented from peeling from the semiconductor layer constituting the ridge portion together with the pad electrode. In addition, if the adhesion layer is made of a material having a strong adhesion to the insulating layer, the pad electrode does not need to be made of a material such as Ti having a strong adhesion to the insulation layer, so the choice of the material constituting the pad electrode is free. The degree can be improved. As a result, since the pad electrode can be made of a material having high thermal conductivity, when heat generated in the light emitting layer during high output operation is transferred to the ohmic electrode, a pad electrode having good thermal conductivity can be obtained. It is possible to dissipate heat. As a result, it is possible to suppress a decrease in heat dissipation characteristics, and thus it is possible to suppress a deterioration in element characteristics and a decrease in element life. Further, if the pad electrode is made of a material having a low electrical resistivity, the resistance against the current injected into the ohmic electrode through the pad electrode is reduced, so that it is possible to suppress an increase in the operating voltage of the element. In addition, if the pad electrode is made of a material having a low internal stress, deformation of the pad electrode can be suppressed during element assembly processes such as electrode formation and element separation (cleavage), so that the surface contacts the pad electrode. It is possible to suppress deformation of the ohmic electrode. Thereby, the adhesive force between the semiconductor layer which comprises a ridge part, and an ohmic electrode can be stabilized. As described above, in one aspect, it is possible to suppress deterioration of element characteristics and a decrease in element lifetime while suppressing peeling of the pad electrode and ohmic electrode, and it is possible to suppress an increase in operating voltage of the element.

  In the semiconductor laser device according to the aforementioned aspect, the adhesion layer preferably has a stronger adhesion to the insulating layer than the pad electrode. According to this structure, even when the pad electrode is formed of a material having low adhesion to the insulating layer, the pad electrode contacting the surface of the adhesion layer is peeled off from the insulating layer together with the adhesion layer by the adhesion layer. Can be suppressed.

  In the semiconductor laser device according to the aforementioned aspect, the adhesion layer that contacts the surface of the insulating layer is preferably formed so as not to contact the ohmic electrode. With this configuration, the heat generated in the light-emitting layer during high-power operation is transferred to the ohmic electrode even when a material with a low thermal conductivity is used as the constituent material of the adhesive layer. In this case, heat can be radiated to the pad electrode side without going through the adhesion layer, so that deterioration of the heat radiation characteristics can be easily suppressed. In addition, even if a material with high electrical resistivity is used as the constituent material of the adhesion layer, current is injected into the ohmic electrode without going through the adhesion layer. It is possible to easily suppress an increase in resistance to the applied current.

  In the semiconductor laser device according to the aforementioned aspect, the lower surface of the ohmic electrode is preferably formed so as to contact only the upper surface of the ridge portion of the semiconductor layer. With this configuration, unlike the case where the lower surface of the ohmic electrode is in contact with both the upper surface of the ridge portion and the surface of the insulating layer, it is not necessary to form the ohmic electrode with a material having strong adhesion to the insulating layer. A material capable of obtaining better ohmic contact can be selected to form an ohmic electrode.

  In the semiconductor laser device according to the aforementioned aspect, the pad electrode is preferably in contact with the side surface of the ridge portion and the side surface of the ohmic electrode. If comprised in this way, the contact area of the pad electrode and ohmic electrode which has favorable thermal conductivity can be increased by comprising a pad electrode with a material with high thermal conductivity, so that heat dissipation characteristics can be improved. Can be improved. Thereby, deterioration of element characteristics and reduction in element life can be further suppressed. Further, by configuring the pad electrode with a material capable of obtaining good ohmic contact with the semiconductor layer constituting the ridge portion, the semiconductor layer and the semiconductor layer of the electrode including the pad electrode and the ohmic electrode are formed. Since the contact area with the layer capable of obtaining a good ohmic contact can be increased, the contact resistance can be further reduced. Thereby, an increase in the operating voltage of the element can be further suppressed.

  In the semiconductor laser device according to the aforementioned aspect, the semiconductor layer preferably includes a nitride-based semiconductor layer, and the ohmic electrode includes at least one of a Pt layer and a Pd layer. With this configuration, the Pt layer and the Pd layer can obtain a good ohmic contact with the nitride-based semiconductor layer, so that the gap between the nitride-based semiconductor layer that forms the ridge portion and the ohmic electrode can be obtained. An increase in the operating voltage of the element due to the increase in contact resistance can be suppressed. In addition, since the Pt layer and the Pd layer have strong adhesion to the nitride semiconductor layer, it is possible to easily prevent the ohmic electrode from peeling from the nitride semiconductor layer constituting the ridge portion.

  In the semiconductor laser device according to the aforementioned aspect, the adhesion layer preferably includes at least one of a Ti layer, a Cr layer, a Ni layer, a Si layer, and a Ge layer. If comprised in this way, since Ti layer, Cr layer, Ni layer, Si layer, and Ge layer have strong adhesive force with respect to an insulating layer, it can suppress that an adhesive layer peels from an insulating layer easily. .

  In the semiconductor laser device according to the aforementioned aspect, the pad electrode preferably includes at least one of an Au layer, an Ag layer, a Cu layer, a Rh layer, a Pd layer, and a Pt layer. With this configuration, the Au layer, the Ag layer, the Cu layer, the Rh layer, the Pd layer, and the Pt layer have a lower electrical resistivity than the Ti layer, so that they can be easily injected into the ohmic electrode via the pad electrode. The resistance to the current that is generated can be reduced. Further, since the Au layer, the Ag layer, the Cu layer, the Rh layer, the Pd layer, and the Pt layer have higher thermal conductivity than the Ti layer, the heat transferred to the pad electrode can be easily dissipated.

  In the semiconductor laser device according to the aforementioned aspect, preferably, the ohmic electrode includes a Pt layer, the adhesion layer includes a Ti layer, and the pad electrode includes an Au layer. If comprised in this way, since the Pt layer has a strong adhesive force to the semiconductor layer, the adhesive force of the ohmic electrode to the semiconductor layer constituting the ridge portion can be easily increased. Further, since the Ti layer has a strong adhesion to the insulating layer, the adhesion of the adhesion layer to the insulating layer can be easily increased. Moreover, since the Au layer has a small hardness (soft), the internal stress of the pad electrode can be easily reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a sectional view showing the structure of a nitride-based semiconductor laser device (blue-violet laser device) according to the first embodiment of the present invention. First, the structure of the nitride-based semiconductor laser device according to the first embodiment will be described with reference to FIG.

  In the nitride-based semiconductor laser device according to the first embodiment, as shown in FIG. 1, an n-type composed of an n-type AlGaN layer having a thickness of about 1.5 μm is formed on an n-type GaN substrate 1 having a thickness of about 150 μm. A clad layer 2 is formed. An active layer (light emitting layer) 3 is formed on the n-type cladding layer 2. The active layer 3 includes three well layers (not shown) made of an undoped InGaN layer having a thickness of about 3.5 nm and three barrier layers made of an undoped InGaN layer having a thickness of about 20 nm. Have a multiple quantum well (MQW) structure. The active layer 3 is an example of the “light emitting layer” in the present invention.

  On the active layer 3, a light guide layer 4 made of an undoped InGaN layer having a thickness of about 50 nm is formed. A cap layer 5 made of an undoped AlGaN layer having a thickness of about 20 nm is formed on the light guide layer 4. On the cap layer 5, a p-type cladding layer 6 made of a p-type AlGaN layer having a convex portion and a flat portion other than the convex portion is formed. The thickness of the flat portion of the p-type cladding layer 6 is about 80 nm, and the height from the upper surface of the flat portion of the convex portion is about 320 nm. A contact layer 7 made of an undoped InGaN layer having a thickness of about 3 nm is formed on the convex portion of the p-type cladding layer 6. The contact layer 7 and the convex portion of the p-type cladding layer 6 constitute a striped (elongated) ridge portion 8 having a width of about 1.5 μm. The light guide layer 4, the cap layer 5, the p-type cladding layer 6 and the contact layer 7 are examples of the “semiconductor layer” and “nitride-based semiconductor layer” of the present invention.

  Here, in the first embodiment, a lower Pt layer (not shown) having a thickness of about 1 nm and an upper Pd layer (not shown) having a thickness of about 10 nm are formed on the contact layer 7 constituting the ridge portion 8. A p-side ohmic electrode 9 is formed. The lower surface of the Pt layer of the p-side ohmic electrode 9 is in contact only with the upper surface of the contact layer 7. The p-side ohmic electrode 9 is an example of the “ohmic electrode” in the present invention.

On the p-type clad layer 6, there is formed a current blocking layer 10 made of an SiO ₂ layer having an opening 10 a that exposes the upper surface of the p-side ohmic electrode 9 and a thickness of about 200 nm. An end 10b on the opening 10a side of the current blocking layer 10 is disposed on the side surface of the p-side ohmic electrode 9, and an end 10c on the side end face side of the element of the current blocking layer 10 is on the element side. It reaches the end face. The current blocking layer 10 is an example of the “insulating layer” in the present invention.

Here, in the first embodiment, the Ti layer 11 having a thickness of about 5 nm is formed so as to contact the surface of the current blocking layer 10 and not to contact the p-side ohmic electrode 9. The Ti layer 11 has an opening 11 a in a region corresponding to the opening 10 a of the current blocking layer 10. Further, the end portion 11b on the opening portion 11a side of the Ti layer 11 is disposed in a region corresponding to the end portion 10b of the current blocking layer 10, and the end portion 11c on the side end face side of the element of the Ti layer 11 is The current blocking layer 10 is disposed in a region corresponding to the end 10c. The Ti layer 11 has stronger adhesion to the SiO ₂ layer constituting the current blocking layer 10 than the lower Pt layer constituting the p-side ohmic electrode 9 and the Au layer of the p-side pad electrode 12 described later. Further, the thermal conductivity and electrical resistivity of the Ti layer 11 are approximately 0.22 W / (cm · K) and approximately 39.0 × 10 ⁻⁸ Ω · m, respectively. The Ti layer 11 is an example of the “adhesion layer” in the present invention.

In the first embodiment, the p-side pad electrode 12 made of an Au layer having a thickness of about 3 μm is formed so as to be in contact with the upper surface of the p-side ohmic electrode 9 and the surface of the Ti layer 11. An end portion 12a on the side end face side of the element of the p-side pad electrode 12 is arranged in a region spaced a predetermined distance from the side end face of the element. The thermal conductivity and electrical resistivity of the Au layer constituting the p-side pad electrode 12 are about 3.18 W / (cm · K) and about 2.3 × 10 ⁻⁸ Ω · m, respectively. The p-side pad electrode 12 is an example of the “pad electrode” in the present invention.

  Further, in a predetermined region on the back surface of the n-type GaN substrate 1, an Al layer (not shown) having a thickness of about 6 nm and a Pd layer having a thickness of about 10 nm are sequentially formed from the back surface side of the n-type GaN substrate 1. (Not shown) and an n-side electrode 13 made of an Au layer (not shown) having a thickness of about 300 nm are formed.

In the first embodiment, as described above, the Ti layer 11 is formed so as to be in contact with the surface of the current blocking layer 10 made of the SiO ₂ layer, and the p-side pad electrode 12 is brought into contact with the surface of the Ti layer 11. As a result, the Ti layer 11 has a strong adhesion to the SiO ₂ layer constituting the current blocking layer 10, so that the p-side pad electrode 12 can be prevented from peeling from the current blocking layer 10. Further, since the peeling of the p-side pad electrode 12 can be suppressed, the p-side ohmic electrode 9 whose upper surface is in contact with the p-side pad electrode 12 is separated from the contact layer 7 constituting the ridge portion 8 together with the p-side pad electrode 12. Peeling can be suppressed. In addition, since it is not necessary to form the p-side pad electrode 12 with a material such as Ti that has a strong adhesion to the current blocking layer 10, the degree of freedom in selecting the material constituting the p-side pad electrode 12 can be improved. As a result, the p-side pad electrode 12 can be made of a material having a high thermal conductivity (Au layer: about 3.18 W / (cm · K)), so that the heat generated in the active layer 3 during high output operation can be reduced. When transmitted to the p-side ohmic electrode 9, heat can be radiated through the p-side pad electrode 9 having good thermal conductivity. As a result, it is possible to suppress a decrease in heat dissipation characteristics, and thus it is possible to suppress a deterioration in element characteristics and a decrease in element life. Further, since the Au layer constituting the p-side pad electrode 12 has a low electrical resistivity (about 2.3 × 10 ⁻⁸ Ω · m), it is injected into the p-side ohmic electrode 9 through the p-side pad electrode 12. The resistance against currents can be reduced. Thereby, it is possible to suppress an increase in the operating voltage of the element. Further, since the Au layer constituting the p-side pad electrode 12 has a small internal stress, the deformation and disconnection of the p-side pad electrode 12 can be suppressed during the element assembly process such as electrode formation and element separation (cleavage). Can do. As a result, the p-side ohmic electrode 9 whose upper surface is in contact with the p-side pad electrode 12 can be prevented from being deformed, so that the contact between the contact layer 7 constituting the ridge portion 8 and the p-side ohmic electrode 9 can be prevented. The wearing force can be stabilized. Further, since Au is a soft metal, it is possible to mitigate the impact when a physical external force is applied to the p-side pad electrode 12 made of the Au layer. As a result, when a physical external force is applied to the p-side pad electrode 12, the force applied to the p-side ohmic electrode 9 below the p-side pad electrode 12 can be reduced. can do. As described above, in the first embodiment, while suppressing the peeling of the p-side pad electrode 12 and the p-side ohmic electrode 9, the deterioration of the element characteristics and the decrease in the element life are suppressed, and the operating voltage of the element is increased. Can be suppressed.

In the first embodiment, the Ti layer 11 is stronger than the lower Pt layer constituting the p-side ohmic electrode 9 and the Au layer of the p-side pad electrode 12 in adhesion to the SiO ₂ layer constituting the current blocking layer 10. Even when the p-side pad electrode 12 is formed of a material such as Au that has low adhesion to the current blocking layer 10 by contacting the surface of the current blocking layer 10, the surface of the Ti layer 11 is reduced by the Ti layer 11. It is possible to prevent the p-side pad electrode 12 in contact with the electrode layer from being peeled off from the current blocking layer 10 together with the Ti layer 11.

In the first embodiment, the Ti layer 11 having a low thermal conductivity (about 0.22 W / (cm · K)) is formed so as not to contact the p-side ohmic electrode 9, thereby enabling the active layer during high output operation. 3 can be radiated to the p-side pad electrode 12 without passing through the Ti layer 11 when the heat generated in the p-side ohmic electrode 9 is transferred to the p-side ohmic electrode 9. it can. Further, by forming the Ti layer 11 having a high electrical resistivity (about 39.0 × 10 ⁻⁸ Ω · m) so as not to contact the upper surface of the p-side ohmic electrode 9, the p-side without the Ti layer 11 is formed. Since current is injected into the ohmic electrode 9, it is possible to easily suppress an increase in resistance to the current injected into the p-side ohmic electrode 9.

  In the first embodiment, the lower surface of the p-side ohmic electrode 9 is configured so that the lower surface of the p-side ohmic electrode 9 is in contact with only the upper surface of the contact layer 7 constituting the ridge portion 8. Unlike the case of contacting both the upper surface and the surface of the current blocking layer 10, it is not necessary to form the p-side ohmic electrode 9 with a material having strong adhesiveness with the current blocking layer 10, and thus a better ohmic contact can be obtained. The p-side ohmic electrode 9 can be formed of a material that can be used.

  In the first embodiment, the contact layer 7 constituting the ridge portion 8 is composed of a nitride semiconductor layer (InGaN layer), and the lower layer of the p-side ohmic electrode 9 formed on the contact layer 7 is a Pt layer. Since the Pt layer can obtain good ohmic contact with the nitride-based semiconductor layer, the contact resistance between the contact layer 7 and the p-side ohmic electrode 9 is increased. It is possible to suppress an increase in the operating voltage of the element to be operated. Further, since the Pt layer has a strong adhesion to the nitride-based semiconductor layer, the p-side ohmic electrode 9 can be easily prevented from peeling off from the contact layer 7. In addition, the p-side ohmic electrode 9 is composed of a lower Pt layer and an upper Pd layer, and the lower Pt layer thickness (about 1 nm) is reduced to reduce the lower Pt layer nitride-based semiconductor. In addition to the effect due to the strong adhesion to the layer, the p-side ohmic electrode 9 having excellent ohmic properties can be formed by the influence of the upper Pd layer, thereby further suppressing the increase in the operating voltage of the element. it can.

  Note that the upper Pd layer constituting the p-side ohmic electrode 9 and the Au layer constituting the p-side pad electrode 12 are made of metal and have high adhesion. Further, since the Ti layer 11 and the Au layer constituting the p-side pad electrode 12 are made of metal, adhesion is strong.

  2 to 12 are cross-sectional views for explaining a manufacturing process of the nitride-based semiconductor laser device according to the first embodiment shown in FIG. A manufacturing process for the nitride-based semiconductor laser device according to the first embodiment is now described with reference to FIGS.

  First, as shown in FIG. 2, an n-type cladding layer 2 composed of an n-type AlGaN layer having a thickness of about 1.5 μm is formed on an n-type GaN substrate 1 by using a MOCVD (Metal Organic Chemical Vapor Deposition) method. After the growth, the active layer 3 is grown on the n-type cladding layer 2. When the active layer 3 is grown, three well layers (not shown) made of an undoped InGaN layer having a thickness of about 3.5 nm, and 3 made of an undoped InGaN layer having a thickness of about 20 nm. Two barrier layers (not shown) are grown alternately. As a result, an active layer 3 having an MQW structure including three well layers and three barrier layers is formed on the n-type cladding layer 2. Subsequently, a light guide layer 4 made of an undoped InGaN layer having a thickness of about 50 nm and a cap layer 5 made of an undoped AlGaN layer having a thickness of about 20 nm are successively grown on the active layer 3. Thereafter, a p-type cladding layer 6 made of a p-type AlGaN layer having a thickness of about 400 nm and a contact layer 7 made of an undoped InGaN layer having a thickness of about 3 nm are successively grown on the cap layer 5.

Next, as shown in FIG. 3, a lower Pt layer (not shown) having a thickness of about 1 nm and an upper Pd layer having a thickness of about 10 nm are formed on the contact layer 7 by using an electron beam evaporation method. A p-side ohmic electrode 9 made of a layer (not shown) is formed. Thereafter, a SiO ₂ layer 21 having a thickness of about 240 nm is formed on the p-side ohmic electrode 9 by plasma CVD, and then corresponds to the ridge portion 8 (see FIG. 1) on the SiO ₂ layer 21. A striped (elongated) resist 22 having a width of about 1.5 μm is formed in the region.

Next, as shown in FIG. 4, the SiO ₂ layer 21 and the p-side ohmic electrode 9 are etched using the resist 22 as a mask by RIE (Reactive Ion Etching) using CF ₄ gas. Thereafter, the resist 22 is removed.

Next, as shown in FIG. 5, by RIE with chlorine-based gas, a SiO ₂ layer 21 as a mask, the middle of the depth of the p-type cladding layer 6 from the upper surface of the contact layer 7 (p-type cladding layer 6 To a depth of about 320 nm from the upper surface of the substrate. As a result, a striped (elongated) ridge portion 8 having a width of about 1.5 μm is formed along with the convex portion of the p-type cladding layer 6 and the contact layer 7. Thereafter, the SiO ₂ layer 21 is removed.

Next, as shown in FIG. 6, by a plasma CVD to cover the entire surface, after forming the SiO ₂ layer 10d having a thickness of about 200 nm, using an electron beam deposition method, an SiO ₂ layer 10d A Ti layer 11 having a thickness of about 5 nm is formed thereon. Thereafter, a resist 23 is formed so as to cover the entire surface.

  Next, as shown in FIG. 7, the surface of the Ti layer 11 located on the ridge portion 8 is thinned by etching the resist 23 over the entire area using a plasma etching method using oxygen gas. Expose. Thereafter, the Ti layer 11 located above the upper surface of the p-side ohmic electrode 9 is etched using the resist 23 as a mask by using a wet etching technique using phosphoric acid. As a result, as shown in FIG. 8, an opening 11 a is formed in a region corresponding to the ridge portion 8 of the Ti layer 11.

Next, the SiO ₂ layer 10d located above the upper surface of the p-side ohmic electrode 9 is etched using the resist 23 as a mask, by RIE using CF ₄ gas. As a result, as shown in FIG. 9, the opening 10a is formed in the region corresponding to the ridge portion 8 of the SiO ₂ layer 10d (see FIG. 8), so that the upper surface of the p-side ohmic electrode 9 is exposed. Thereby, the current blocking layer 10 is formed. Thereafter, the resist 23 is removed.

  Next, as shown in FIG. 10, a resist 24 is formed in a region corresponding to the end portion 11 c on the side end face side of the element on the Ti layer 11.

  Next, as shown in FIG. 11, a p-side pad made of an Au layer having a thickness of about 3 μm is formed on the upper surface of the resist 24, the Ti layer 11, and the exposed p-side ohmic electrode 9 using a resistance heating vapor deposition method. The electrode 12 is formed. Thereafter, the p-side pad electrode 12 on the resist 24 is removed by removing the resist 24. As a result, as shown in FIG. 12, the end portion 12a on the side end face side of the element of the p-side pad electrode 12 is arranged in a region spaced a predetermined distance from the side end face of the element.

  Next, the back surface of the n-type GaN substrate 1 is polished until the thickness of the n-type GaN substrate 1 becomes about 150 μm. Thereafter, as shown in FIG. 1, an Al layer (not shown) having a thickness of about 6 nm in order from the back surface side of the n-type GaN substrate 1 in a predetermined region on the back surface of the n-type GaN substrate 1; An n-side electrode 13 composed of a Pd layer (not shown) having a thickness of about 10 nm and an Au layer (not shown) having a thickness of about 300 nm is formed. Finally, the nitride semiconductor laser device according to the first embodiment is formed by separating (cleaving) the device into chips.

  In the manufacturing process of the first embodiment, as described above, after the p-side ohmic electrode 9 is formed on the contact layer 7, predetermined regions of the p-side ohmic electrode 9, the contact layer 7, and the p-type cladding layer 6 are etched. Unlike the case where the p-side ohmic electrode 9 is formed after forming the ridge 8 by forming the ridge 8 by this, it is necessary to form a mask for forming the ridge 8 on the surface of the contact layer 7. Therefore, there is no inconvenience that impurities such as a residue of the mask material adhere to the surface of the contact layer 7 because the mask on the contact layer 7 is not completely removed after the ridge portion 8 is formed. Thereby, it can suppress that an impurity mixes between the contact layer 7 which comprises the ridge part 8, and the p side ohmic electrode 9. FIG. As a result, it is possible to suppress the adhesion force between the contact layer 7 constituting the ridge portion 8 and the p-side ohmic electrode 9 from being weakened, and the contact layer 7 constituting the ridge portion 8 and the p-side ohmic electrode 9 can be prevented from increasing in contact resistance.

(Second Embodiment)
FIG. 13 is a sectional view showing the structure of a nitride-based semiconductor laser device (blue-violet laser device) according to the second embodiment of the present invention. Referring to FIG. 13, in the second embodiment, unlike the first embodiment, the p-side pad electrode is brought into contact with the side surface of the ridge portion and the p-side ohmic electrode, and the p-side pad electrode is used as the lower layer Pd. A case in which a layer and an upper Au layer are used will be described.

  In the nitride-based semiconductor laser device according to the second embodiment, as shown in FIG. 13, an n-type cladding layer 2 and an active layer having the same composition and thickness as those of the first embodiment are formed on an n-type GaN substrate 1. 3, a light guide layer 4, a cap layer 5, a p-type cladding layer 6 and a contact layer 7 are sequentially formed. Similarly to the first embodiment, the p-type cladding layer 6 has a convex portion and a flat portion other than the convex portion, and the contact layer 7 is formed on the convex portion of the p-type cladding layer 6. Yes. The contact layer 7 and the convex portion of the p-type cladding layer 6 form a striped (elongated) ridge portion 8 having a width of about 1.5 μm.

  Here, in the second embodiment, as in the first embodiment, a lower Pt layer (not shown) having a thickness of about 1 nm and a thickness of about 10 nm are formed on the contact layer 7 constituting the ridge portion 8. A p-side ohmic electrode 9 made of an upper Pd layer (not shown) having s is formed. The lower surface of the Pt layer of the p-side ohmic electrode 9 is in contact only with the upper surface of the contact layer 7.

Further, on the p-type cladding layer 6, an SiO ₂ layer having an opening 30 a that exposes an upper surface and a side surface of the p-side ohmic electrode 9 and a part of the side surface of the ridge portion 8 and a thickness of about 200 nm. A current blocking layer 30 made of is formed. An end 30b of the current blocking layer 30 on the opening 30a side is disposed on a side surface below the contact layer 7 of the ridge portion 8, and an end 30c on the side of the element of the current blocking layer 30 is , Reaching the side end face of the element. The current blocking layer 30 is an example of the “insulating layer” in the present invention.

  Here, in the second embodiment, the Ti layer 31 having a thickness of about 5 nm is formed so as to be in contact with the surface of the current blocking layer 30 and not in contact with the p-side ohmic electrode 9. The Ti layer 31 has an opening 31 a in a region corresponding to the opening 30 a of the current blocking layer 30. In addition, the end 31b on the opening 31a side of the Ti layer 31 is disposed in a region corresponding to the end 30b of the current blocking layer 30, and the end 31c on the side end face side of the element of the Ti layer 31 is The current blocking layer 30 is disposed in a region corresponding to the end 30c. The Ti layer 31 is an example of the “adhesion layer” in the present invention.

In the second embodiment, the lower layer having a thickness of about 10 nm is in contact with the upper surface of the p-side ohmic electrode 9, the side surfaces of the p-side ohmic electrode 9 and the ridge portion 8, and the surface of the Ti layer 31. A p-side pad electrode 32 composed of a Pd layer (not shown) and an upper Au layer (not shown) having a thickness of about 3 μm is formed. An end portion 32a on the side end face side of the element of the p-side pad electrode 32 is arranged in a region spaced a predetermined distance from the side end face of the element. The thermal conductivity and electrical resistivity of the Pd layer constituting the p-side pad electrode 32 are about 0.72 W / (cm · K) and about 10.7 × 10 ⁻⁸ Ω · m, respectively. The thermal conductivity and electrical resistivity of the layers are about 3.18 W / (cm · K) and about 2.3 × 10 ⁻⁸ Ω · m, respectively. The p-side pad electrode 32 is an example of the “pad electrode” in the present invention.

  An n-side electrode 13 having the same composition and thickness as in the first embodiment is formed in a predetermined region on the back surface of the n-type GaN substrate 1.

  In the second embodiment, as described above, the p-side pad electrode 32 composed of the lower Pd layer and the upper Au layer is brought into contact with the upper surface and the side surface of the p-side ohmic electrode 9 to achieve good heat conduction. Since the contact area between the p-side pad electrode 32 and the p-side ohmic electrode 9 having the property increases, the heat dissipation characteristics can be improved as compared with the first embodiment. Thereby, it is possible to suppress the deterioration of the element characteristics and the decrease of the element life as compared with the first embodiment. Further, the p-side pad electrode 32 is composed of a lower Pd layer and an upper Au layer, and the lower Pd layer of the p-side pad electrode 32 is brought into contact with the side surface of the ridge portion 8 (contact layer 7). As a result, the contact area between the contact layer 7 and a layer capable of obtaining good ohmic contact with the contact layer 7 of the p-side electrode including the p-side pad electrode 32 and the p-side ohmic electrode 9 is increased. The contact resistance can be made lower than in the first embodiment. Thereby, the operating voltage of the element can be reduced as compared with the first embodiment.

  The remaining effects of the second embodiment are similar to those of the aforementioned first embodiment.

  14 to 20 are cross-sectional views for explaining a manufacturing process of the nitride-based semiconductor laser device according to the second embodiment shown in FIG. A manufacturing process for the nitride-based semiconductor laser device according to the second embodiment is now described with reference to FIGS.

  First, up to the ridge portion 8 is formed using a process similar to that of the first embodiment shown in FIGS.

Next, as shown in FIG. 14, by plasma CVD to cover the entire surface, after forming the SiO ₂ layer 30d having a thickness of about 200 nm, using an electron beam deposition method, an SiO ₂ layer 30d A Ti layer 31 having a thickness of about 5 nm is formed thereon. Thereafter, a resist 41 is formed so as to cover the entire surface.

  Next, as shown in FIG. 15, the surface of the Ti layer 31 located on the ridge portion 8 is reduced by thinning the resist 41 by etching it over the entire area using a plasma etching method using oxygen gas. Expose. Thereafter, using a wet etching technique using phosphoric acid, the resist 41 is used as a mask and the Ti layer 31 is located on the side surface below the contact layer 7 of the ridge portion 8 from the region located on the upper surface of the ridge portion 8. Etch up to the area. Thereby, as shown in FIG. 16, an opening 31 a is formed in a region corresponding to the ridge portion 8 of the Ti layer 31.

Next, using the RIE method with CF ₄ gas, using the resist 41 as a mask, from the region located on the upper surface of the ridge portion 8 of the SiO ₂ layer 30d to the side surface below the contact layer 7 of the ridge portion 8 Etch up to the region where it is located. Thus, as shown in FIG. 17, since the opening portion 30a is formed in a region corresponding to the ridge portion 8 of the SiO ₂ layer 30d (see FIG. 16), the upper and side surfaces of the p-side ohmic electrode 9, a ridge portion A part of the side surface of 8 is exposed. Thereby, the current blocking layer 30 is formed. Thereafter, the resist 41 is removed.

  Next, as shown in FIG. 18, a resist 42 is formed in a region corresponding to the end portion 31 c on the side end face side of the element on the Ti layer 31.

  Next, as shown in FIG. 19, the structure shown in FIG. 18 is mounted on a substrate holder (not shown) of an electron beam evaporation apparatus. Then, while rotating the substrate holder of the electron beam evaporation apparatus, on the upper surface of the resist 42 and the Ti layer 31, on the upper surface and side surface of the exposed p-side ohmic electrode 9, and on the side surface of the exposed ridge portion 8, A p-side pad electrode 32 composed of a lower Pd layer (not shown) having a thickness of about 10 nm and an upper Au layer (not shown) having a thickness of about 3 μm is formed. Thereafter, the p-side pad electrode 32 on the resist 42 is removed by removing the resist 42. As a result, as shown in FIG. 20, the end portion 32a on the side end face side of the element of the p-side pad electrode 32 is arranged in a region spaced a predetermined distance from the side end face of the element.

  Next, the back surface of the n-type GaN substrate 1 is polished until the thickness of the n-type GaN substrate 1 becomes about 150 μm. Thereafter, as shown in FIG. 13, an n-side electrode 13 having the same composition and thickness as in the first embodiment is formed in a predetermined region on the back surface of the n-type GaN substrate 1. Finally, the nitride semiconductor laser device according to the second embodiment is formed by separating (cleaving) the device into chips.

(Third embodiment)
FIG. 21 is a sectional view showing the structure of a nitride-based semiconductor laser device (blue-violet laser device) according to the third embodiment of the present invention. Referring to FIG. 21, in the third embodiment, unlike the first and second embodiments, the p-side ohmic electrode is composed of only the Pt layer, and the p-side pad electrode is formed of the lower Ag layer and the upper layer. A case will be described in which an Au layer and an adhesion layer in contact with an insulating layer are constituted by a lower Ti layer and an upper Au layer.

  In the nitride-based semiconductor laser device according to the third embodiment, as shown in FIG. 21, an n-type having the same composition and thickness as in the first embodiment is formed on an n-type GaN substrate 51 having a thickness of about 100 μm. A clad layer 2, an active layer 3, a light guide layer 4, a cap layer 5, a p-type clad layer 6 and a contact layer 7 are sequentially formed. Similarly to the first embodiment, the p-type cladding layer 6 has a convex portion and a flat portion other than the convex portion, and the contact layer 7 is formed on the convex portion of the p-type cladding layer 6. Yes. The contact layer 7 and the convex portion of the p-type cladding layer 6 form a striped (elongated) ridge portion 8 having a width of about 1.5 μm.

  Here, in the third embodiment, the p-side ohmic electrode 59 made of a Pt layer having a thickness of about 5 nm is formed on the contact layer 7 constituting the ridge portion 8. The lower surface of the p-side ohmic electrode 59 is in contact only with the upper surface of the contact layer 7. Further, the thickness (about 5 nm) of the p-side ohmic electrode 59 is a thickness capable of transmitting the light generated in the active layer 3. The p-side ohmic electrode 59 is an example of the “ohmic electrode” in the present invention.

On the p-type cladding layer 6, there is formed a current blocking layer 60 made of an Al ₂ O ₃ layer having an opening 60 a that exposes the upper surface of the p-side ohmic electrode 59 and a thickness of about 200 nm. . An end 60 b on the opening 60 a side of the current blocking layer 60 is disposed on the side surface of the p-side ohmic electrode 59. Further, the end 60 b on the opening 60 a side of the current blocking layer 60 is rounded and protrudes upward from the upper surface of the p-side ohmic electrode 59. Further, the end portion 60c on the side end face side of the element of the current blocking layer 60 reaches the side end face of the element. The current blocking layer 60 is an example of the “insulating layer” in the present invention.

  Here, in the third embodiment, a lower Ti layer (not shown) having a thickness of about 5 nm so as to be in contact with the surface of the current blocking layer 60 and not in contact with the p-side ohmic electrode 59; A multilayer adhesion layer 61 made of an upper Au layer (not shown) having a thickness of about 10 nm is formed. The upper Au layer of the multilayer adhesion layer 61 functions as a protective layer for the lower Ti layer. The multilayer adhesion layer 61 has an opening 61 a in a region corresponding to the opening 60 a of the current blocking layer 60. Further, the end portion 61b of the multilayer adhesion layer 61 on the opening 61a side is disposed in a region corresponding to the end portion 60b of the current blocking layer 60, and the end portion 61c of the multilayer adhesion layer 61 on the side end face side of the element. Are arranged in a region spaced a predetermined distance from the side end face of the element. The multilayer adhesion layer 61 is an example of the “adhesion layer” in the present invention.

In the third embodiment, a lower Ag layer (not shown) having a thickness of about 50 nm and a thickness of about 3 μm are provided so as to contact the upper surface of the p-side ohmic electrode 59 and the surface of the multilayer adhesion layer 61. A p-side pad electrode 62 made of an upper Au layer (not shown) is formed. The lower Ag layer constituting the p-side pad electrode 62 has a high reflectance with respect to the light generated in the active layer 3. Further, the end portion 62a on the side end face side of the element of the p-side pad electrode 62 is arranged in a region spaced a predetermined distance from the side end face of the element. The thermal conductivity and electrical resistivity of the Ag layer constituting the p-side pad electrode 62 are about 4.29 W / (cm · K) and about 1.6 × 10 ⁻⁸ Ω · m, respectively. The thermal conductivity and electrical resistivity of the layers are about 3.18 W / (cm · K) and about 2.3 × 10 ⁻⁸ Ω · m, respectively. The p-side pad electrode 62 is an example of the “pad electrode” in the present invention.

  An n-side electrode 13 having the same composition and thickness as in the first embodiment is formed in a predetermined region on the back surface of the n-type GaN substrate 51.

  In the third embodiment, as described above, the p-side pad electrode 62 is formed by bringing the p-side pad electrode 62 composed of the lower Ag layer and the upper Au layer into contact with the upper surface of the p-side ohmic electrode 59. The thermal conductivity (about 4.29 W / (cm · K)) of the lower Ag layer constituting the thermal conductivity of the Au layer constituting the p-side pad electrode 12 of the first embodiment (about 3.18 W / (Cm · K)) and the thermal conductivity (about 0.72 W / (cm · K)) of the lower Pd layer constituting the p-side pad electrode 32 of the second embodiment. The heat dissipation characteristics can be improved as compared with the second embodiment. Thereby, it is possible to suppress the deterioration of the element characteristics and the decrease of the element life as compared with the first and second embodiments. In addition, by setting the thickness (about 5 nm) of the p-side ohmic electrode 59 to a thickness capable of transmitting the light generated in the active layer 3, the light transmitted through the p-side ohmic electrode 59 3 is reflected to the active layer 3 side by the Ag layer under the p-side pad electrode 62 having a high reflectance with respect to the light generated in 3, so that light confinement can be improved. Thereby, the luminous efficiency of the element can be improved.

  In the third embodiment, the end portion 61c on the side end face side of the element of the multilayer adhesion layer 61 in contact with the surface of the current blocking layer 60 is disposed in a region spaced a predetermined distance from the side end face of the element. The region where the parasitic capacitance composed of the multilayer adhesion layer 61, the current blocking layer 60, and the p-type cladding layer 6 is formed can be reduced. Thereby, it can suppress that the response speed of an element becomes slow.

  The remaining effects of the third embodiment are similar to those of the aforementioned first embodiment.

  22 to 32 are cross-sectional views for explaining a manufacturing process of the nitride-based semiconductor laser device according to the third embodiment shown in FIG. A manufacturing process for the nitride semiconductor laser element according to the third embodiment is now described with reference to FIGS.

  First, as shown in FIG. 22, nitride-based semiconductor layers (2 to 7) are sequentially grown on the n-type GaN substrate 51 using a process similar to that of the first embodiment shown in FIG. 2. Next, a p-side ohmic electrode 59 made of a Pt layer having a thickness of about 5 nm is formed on the contact layer 7 by using an electron beam evaporation method. Thereafter, heat treatment is performed at about 500 ° C. for about 10 minutes in a nitrogen atmosphere. Thereby, since a diffusion region (not shown) is formed at the interface between the contact layer 7 and the p-side ohmic electrode 59, the adhesion of the p-side ohmic electrode 59 to the contact layer 7 can be increased.

Next, as shown in FIG. 23, an SiO ₂ layer 71 having a thickness of about 100 nm and an Al ₂ O ₃ layer 72 having a thickness of about 200 nm are sequentially formed on the p-side ohmic electrode 59 by sputtering. To do. Thereafter, a striped (elongated) resist 73 having a width of about 1.5 μm is formed in a region corresponding to the ridge portion 8 (see FIG. 21) on the Al ₂ O ₃ layer 72.

Next, as shown in FIG. 24, the Al ₂ O ₃ layer 72, the SiO ₂ layer 71, and the p-side ohmic electrode 59 are etched using the resist 73 as a mask by using the RIE method using CF ₄ gas. Thereafter, the resist 73 is removed.

Next, as shown in FIG. 25, by RIE with chlorine-based gas, the the Al ₂ O ₃ layer 72 as a mask, the middle of the depth of the p-type cladding layer 6 from the upper surface of the contact layer 7 (p-type cladding Etch from the top surface of layer 6 to a depth of about 320 nm. As a result, a striped (elongated) ridge portion 8 having a width of about 1.5 μm is formed along with the convex portion of the p-type cladding layer 6 and the contact layer 7.

Next, as shown in FIG. 26, a wet etching technique using buffered hydrofluoric acid is used to etch from the side surface of the SiO ₂ layer 71 to a depth of about 150 nm in the lateral direction.

Next, as shown in FIG. 27, the structure shown in FIG. 26 is mounted on a substrate holder (not shown) of the sputtering apparatus. Then, while rotating the substrate holder of the sputtering apparatus, a current blocking layer 60 made of an Al ₂ O ₃ layer having a thickness of about 200 nm is formed so as to cover a region other than the surface of the SiO ₂ layer 71. Subsequently, a multilayer adhesion layer 61 composed of a lower Ti layer (not shown) having a thickness of about 5 nm and an upper Au layer (not shown) having a thickness of about 10 nm is formed on the current blocking layer 60. Form. Thereafter, using a wet etching using buffered hydrofluoric acid, by removing the SiO ₂ layer 71 is removed _{the Al} 2 _{O 3} layer 72, the current blocking layer 60 and the multilayer deposition layers 61 on the SiO ₂ layer 71 . As a result, as shown in FIG. 28, openings 60a and 61a are formed in regions corresponding to the ridge 8 of the current blocking layer 60 and the multilayer adhesion layer 61, respectively. Further, the end 60 b on the opening 60 a side of the current blocking layer 60 is formed so as to be rounded and protrude upward from the upper surface of the p-side ohmic electrode 59.

  Next, as shown in FIG. 29, a resist 74 is formed in a region corresponding to the end portion 61 c on the side end face side of the element on the multilayer adhesion layer 61.

  Next, as shown in FIG. 30, a lower Ag layer (FIG. 30) having a thickness of about 50 nm is formed on the upper surfaces of the resist 74, the multilayer adhesion layer 61, and the exposed p-side ohmic electrode 59 using a resistance heating vapor deposition method. And a p-side pad electrode 62 composed of an upper Au layer (not shown) having a thickness of about 3 μm. Thereafter, the p-side pad electrode 62 on the resist 74 is removed by removing the resist 74. Thereby, as shown in FIG. 31, the end portions 62a on the side end face side of the element of the p-side pad electrode 62 are respectively arranged in regions spaced from the side end face of the element by a predetermined distance.

Next, as shown in FIG. 32, the multilayer adhesion layer 61 is etched using the p-side pad electrode 62 as a mask by RIE using CF ₄ gas. Thus, the end portion 61c on the side end face side of the element of the multilayer adhesion layer 61 is arranged in a region spaced a predetermined distance from the side end face of the element.

  Next, the back surface of the n-type GaN substrate 51 is polished until the thickness of the n-type GaN substrate 51 reaches about 100 μm. Thereafter, as shown in FIG. 21, the n-side electrode 13 having the same composition and thickness as in the first embodiment is formed in a predetermined region on the back surface of the n-type GaN substrate 51. Finally, the nitride semiconductor laser device according to the third embodiment is formed by separating (cleaving) the device into chips.

In the manufacturing process of the third embodiment, as described above, to form the SiO ₂ layer 71 and _{the Al} 2 _{O 3} layer 72 on the p-side ohmic electrode 59 on the ridge portion 8, other than the side surface of the SiO ₂ layer 71 After the current block layer 60 is formed so as to cover the region, the SiO ₂ layer 71 is removed, thereby forming an opening 60a in a region corresponding to the ridge portion 8 of the current block layer 60, whereby the ridge portion 8 Even when the height is as small as about 325 nm, the current blocking layer 60 having the opening 60 a in the region corresponding to the ridge portion 8 of the current blocking layer 60 can be easily formed.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and further includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  For example, in the first to third embodiments, the example in which the present invention is applied to the nitride-based semiconductor laser element (blue-violet laser element) has been described. However, the present invention is not limited thereto, and the nitride-based semiconductor laser element is not limited thereto. The present invention can also be applied to other semiconductor laser elements.

  In the first to third embodiments, as the ohmic electrode, an ohmic electrode composed of a lower Pt layer and an upper Pd layer or an ohmic electrode composed of only a Pt layer is used. Not limited to this, an ohmic electrode made of only a Pd layer may be used. Alternatively, an ohmic electrode composed of a lower Pd layer and an upper Pt layer may be used.

  In the first to third embodiments, the adhesion layer contacting the insulating layer (current blocking layer) is constituted by a single adhesion layer made of a Ti layer or a lower Ti layer and an upper Au layer. Although a multi-layer adhesion layer is used, the present invention is not limited to this, and as an adhesion layer in contact with an insulating layer (current blocking layer), a metal layer such as a Ti layer, a Cr layer, or a Ni layer, a Si layer, a Ge layer It is sufficient that at least one of the semiconductor layers such as is included. Further, a multilayer structure of three or more layers may be used.

  In the first to third embodiments, as a pad electrode, a pad electrode composed only of an Au layer, a pad electrode composed of a lower Pd layer and an upper Au layer, or a lower Ag layer and an upper Au layer However, the present invention is not limited to this, and the pad electrode may include at least one of an Au layer, an Ag layer, a Cu layer, a Rh layer, a Pd layer, and a Pt layer. That's fine. Further, a multilayer structure of three or more layers may be used.

In the first to third embodiments, the insulating layer (current blocking layer) is an insulating layer made of an SiO ₂ layer or an insulating layer made of an Al ₂ O ₃ layer. However, the present invention is not limited to this. The insulating layer (current blocking layer) only needs to contain at least one of SiO ₂ layer, SiN layer, TaO _X layer, Al ₂ O ₃ layer, ZrO ₂ layer, and NbO _X. Further, a multilayer structure of two or more layers may be used. Note that if the insulating layer (current blocking layer) has a multilayer structure of two or more layers, light can be reflected by the difference in refractive index at the interface between the layers, so that light confinement can be improved.

It is sectional drawing which showed the structure of the nitride type semiconductor laser element (blue-violet laser element) by 1st Embodiment of this invention. FIG. 8 is a cross-sectional view for explaining the manufacturing process for the nitride-based semiconductor laser device according to the first embodiment shown in FIG. 1. FIG. 8 is a cross-sectional view for explaining the manufacturing process for the nitride-based semiconductor laser device according to the first embodiment shown in FIG. 1. FIG. 8 is a cross-sectional view for explaining the manufacturing process for the nitride-based semiconductor laser device according to the first embodiment shown in FIG. 1. FIG. 8 is a cross-sectional view for explaining the manufacturing process for the nitride-based semiconductor laser device according to the first embodiment shown in FIG. 1. FIG. 8 is a cross-sectional view for explaining the manufacturing process for the nitride-based semiconductor laser device according to the first embodiment shown in FIG. 1. FIG. 8 is a cross-sectional view for explaining the manufacturing process for the nitride-based semiconductor laser device according to the first embodiment shown in FIG. 1. FIG. 8 is a cross-sectional view for explaining the manufacturing process for the nitride-based semiconductor laser device according to the first embodiment shown in FIG. 1. FIG. 8 is a cross-sectional view for explaining the manufacturing process for the nitride-based semiconductor laser device according to the first embodiment shown in FIG. 1. FIG. 8 is a cross-sectional view for explaining the manufacturing process for the nitride-based semiconductor laser device according to the first embodiment shown in FIG. 1. FIG. 8 is a cross-sectional view for explaining the manufacturing process for the nitride-based semiconductor laser device according to the first embodiment shown in FIG. 1. FIG. 8 is a cross-sectional view for explaining the manufacturing process for the nitride-based semiconductor laser device according to the first embodiment shown in FIG. 1. It is sectional drawing which showed the structure of the nitride type semiconductor laser element (blue-violet laser element) by 2nd Embodiment of this invention. FIG. 14 is a cross-sectional view for explaining a manufacturing process for the nitride-based semiconductor laser device according to the second embodiment shown in FIG. 13. FIG. 14 is a cross-sectional view for explaining a manufacturing process for the nitride-based semiconductor laser device according to the second embodiment shown in FIG. 13. FIG. 14 is a cross-sectional view for explaining a manufacturing process for the nitride-based semiconductor laser device according to the second embodiment shown in FIG. 13. FIG. 14 is a cross-sectional view for explaining a manufacturing process for the nitride-based semiconductor laser device according to the second embodiment shown in FIG. 13. FIG. 14 is a cross-sectional view for explaining a manufacturing process for the nitride-based semiconductor laser device according to the second embodiment shown in FIG. 13. FIG. 14 is a cross-sectional view for explaining a manufacturing process for the nitride-based semiconductor laser device according to the second embodiment shown in FIG. 13. FIG. 14 is a cross-sectional view for explaining a manufacturing process for the nitride-based semiconductor laser device according to the second embodiment shown in FIG. 13. It is sectional drawing which showed the structure of the nitride type semiconductor laser element (blue-violet laser element) by 3rd Embodiment of this invention. FIG. 22 is a cross-sectional view for illustrating the manufacturing process for the nitride-based semiconductor laser device according to the third embodiment shown in FIG. 21. FIG. 22 is a cross-sectional view for illustrating the manufacturing process for the nitride-based semiconductor laser device according to the third embodiment shown in FIG. 21. FIG. 22 is a cross-sectional view for illustrating the manufacturing process for the nitride-based semiconductor laser device according to the third embodiment shown in FIG. 21. FIG. 22 is a cross-sectional view for illustrating the manufacturing process for the nitride-based semiconductor laser device according to the third embodiment shown in FIG. 21. FIG. 22 is a cross-sectional view for illustrating the manufacturing process for the nitride-based semiconductor laser device according to the third embodiment shown in FIG. 21. FIG. 22 is a cross-sectional view for illustrating the manufacturing process for the nitride-based semiconductor laser device according to the third embodiment shown in FIG. 21. FIG. 22 is a cross-sectional view for illustrating the manufacturing process for the nitride-based semiconductor laser device according to the third embodiment shown in FIG. 21. FIG. 22 is a cross-sectional view for illustrating the manufacturing process for the nitride-based semiconductor laser device according to the third embodiment shown in FIG. 21. FIG. 22 is a cross-sectional view for illustrating the manufacturing process for the nitride-based semiconductor laser device according to the third embodiment shown in FIG. 21. FIG. 22 is a cross-sectional view for illustrating the manufacturing process for the nitride-based semiconductor laser device according to the third embodiment shown in FIG. 21. FIG. 22 is a cross-sectional view for illustrating the manufacturing process for the nitride-based semiconductor laser device according to the third embodiment shown in FIG. 21. It is sectional drawing which showed the structure of the conventional semiconductor laser element.

Explanation of symbols

3 Active layer (light emitting layer)
4 Light guide layer (semiconductor layer, nitride semiconductor layer)
5 Cap layer (semiconductor layer, nitride semiconductor layer)
6 p-type cladding layer (semiconductor layer, nitride-based semiconductor layer)
7 Contact layer (semiconductor layer, nitride semiconductor layer)
8 Ridge part 9, 59 p-side ohmic electrode (ohmic electrode)
10, 30, 60 Current blocking layer (insulating layer)
11, 31 Ti layer (adhesion layer)
12, 32, 62 p-side pad electrode (pad electrode)
61 Multi-layer adhesion layer (adhesion layer)

Claims (9)

A semiconductor layer formed on the light emitting layer and having a convex ridge;
An ohmic electrode formed on the ridge portion of the semiconductor layer;
An insulating layer formed on the semiconductor layer and formed on at least a part of a side surface of the ridge;
An adhesion layer formed on the insulating layer and including at least one of a metal and a semiconductor in contact with the surface of the insulating layer;
A semiconductor laser device comprising: the ohmic electrode; and a pad electrode in contact with a surface of the adhesion layer.   The semiconductor laser element according to claim 1, wherein the adhesion layer has a stronger adhesion to the insulating layer than the pad electrode.   3. The semiconductor laser device according to claim 1, wherein the adhesion layer that contacts the surface of the insulating layer is formed so as not to contact the ohmic electrode.   4. The semiconductor laser device according to claim 1, wherein a lower surface of the ohmic electrode is formed so as to contact only an upper surface of the ridge portion of the semiconductor layer.   5. The semiconductor laser device according to claim 1, wherein the pad electrode is in contact with a side surface of the ridge portion and a side surface of the ohmic electrode. The semiconductor layer includes a nitride-based semiconductor layer,
The semiconductor laser element according to claim 1, wherein the ohmic electrode includes at least one of a Pt layer and a Pd layer.   The semiconductor laser device according to claim 1, wherein the adhesion layer includes at least one of a Ti layer, a Cr layer, a Ni layer, a Si layer, and a Ge layer.   The semiconductor laser device according to claim 1, wherein the pad electrode includes at least one of an Au layer, an Ag layer, a Cu layer, a Rh layer, a Pd layer, and a Pt layer. The ohmic electrode includes a Pt layer,
The adhesion layer includes a Ti layer;
The semiconductor laser device according to claim 1, wherein the pad electrode includes an Au layer.

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