JP5402222B2 - Manufacturing method of semiconductor device - Google Patents

Description

  The present invention relates to a semiconductor element and a manufacturing method thereof, and more particularly to a semiconductor element having excellent reliability while realizing a simple manufacturing process that is not restricted by materials such as an electrode and a protective film, and a manufacturing method thereof.

  Conventionally, a compound semiconductor element has been proposed in which a striped ridge is formed on the surface of a p-side semiconductor layer in a compound semiconductor element, and an active layer under the ridge is a waveguide region. In such a compound semiconductor element, a stripe ridge is usually formed in a compound semiconductor layer laminated on a substrate, and an electrode is electrically connected to the stripe ridge.

JP 2005-347630 A JP 2008-109092 A

However, in the method of Patent Document 2, in the semiconductor element manufacturing process, there are cases where there are restrictions on the material of the protective film and the electrode, so that various materials cannot be selected, and in some cases, element characteristics are sacrificed. However, there was a problem that an expensive material had to be selected.
Further, the semiconductor laser element of Patent Document 2 has a problem that desired beam characteristics cannot be obtained and a current leak occurs during operation.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a semiconductor device with improved reliability and a method for manufacturing the same while realizing a simple manufacturing process that is not subject to material limitations.

  The semiconductor element of the present invention is a semiconductor element comprising a semiconductor layer stacked on a substrate, a stripe-shaped ridge formed on the surface of the semiconductor layer, and an electrode formed on the ridge. The side surface of the ridge is covered with a protective film, and the tip of the protective film is formed at a position higher than the upper surface of the ridge, and an electrode is formed on the top surface of the ridge and the tip of the protective film. It is characterized by having.

  The electrode is preferably bonded to the semiconductor layer only on the top surface of the ridge.

It is preferable that a pad electrode is coated on the protective film and the electrode.

  The tip of the protective film is preferably higher than the upper surface of the ridge by 1000 mm or more.

In addition, a method for manufacturing a semiconductor element of the present invention includes
(A) stacking a semiconductor layer on a substrate and forming a mask layer having a predetermined shape on the semiconductor layer;
(B) removing a part of the semiconductor layer from the opening of the mask layer to form a ridge;
(C) forming a protective film at least in a region extending from the bottom surface region of the ridge to the mask layer on the top surface of the ridge;
(D) forming a second mask layer on the protective film other than the top surface of the ridge;
(E) removing the mask layer and the protective film on the ridge upper surface, thereby forming a tip of the protective film at a position higher than the ridge;
(F) forming an electrode material film on at least the top surface of the ridge and the tip of the protective film.

In the step (d), the second mask layer is preferably formed in a region other than the top surface of the ridge by etching back after forming the second mask layer.

Preferably, the upper surface of the second mask layer in the step (d) is formed at a position higher than the upper surface of the ridge.

  According to the semiconductor element of the present invention, it is possible to obtain a semiconductor element with improved reliability while realizing a simple manufacturing process that is not restricted by materials.

It is a schematic cross-sectional view explaining the structure of the semiconductor element which concerns on one embodiment of this invention. It is a schematic cross-sectional view of the principal part for demonstrating the structure of the semiconductor element which concerns on one embodiment of this invention. It is a schematic sectional process drawing of the principal part for demonstrating the manufacturing method of the semiconductor element of this invention. It is a schematic sectional process drawing of the principal part for demonstrating the manufacturing method of the semiconductor element of this invention.

  The semiconductor element of the present invention mainly comprises a substrate, a semiconductor layer, an electrode, and a protective film. Such a semiconductor element typically includes a semiconductor layer 20 in which an n-side semiconductor layer 11, an active layer 12, and a p-side semiconductor layer 13 are sequentially stacked on a substrate 10 as shown in FIG. A stripe-shaped ridge 14 is formed on the surface. The protective film 16 covers the ridge side surface 14b from the ridge bottom surface 14a formed on the semiconductor layer 20, and the tip 16a of the protective film 16 is formed at a position higher than the ridge upper surface 14c. The electrode 15 covers the upper surface of the ridge 14 and the tip of the protective film 16.

Here, the tip 16a of the protective film 16 formed on the side surface 14b of the ridge of the semiconductor element is disposed at a position higher than the ridge upper surface 14c, and is disposed at a position lower than the upper surface of the electrode 15. Here, the protective film 16 does not cover the upper surface of the ridge, and the ridge width can be utilized to the maximum for the contact area with the electrode.
In particular, when a single mode semiconductor laser device is manufactured, even if the width of the electrode formed on the ridge is adjusted, if the ridge width is wide, the light beam from the laser device becomes multimode. Therefore, it is not possible to provide a single mode semiconductor laser device simply by adjusting the width of the electrode on the ridge. In the semiconductor device of the present invention, only the electrode is formed on the ridge upper surface, and the ridge width can be utilized to the maximum. Therefore, stable lateral light confinement can also be realized.

Further, the semiconductor element includes a pad electrode 18 that covers the electrode 15 on the ridge 14 and the protective film 16.
Further, in such a semiconductor element, a second protective film may be formed on the side surface of the semiconductor layer 20. Although not shown, a protective film made of, for example, a dielectric film is formed on the resonator surface of the semiconductor element. The protective film 16 and the second protective film may be insulators, and the material is not particularly limited.

  As shown in FIG. 1, an n-electrode 19 is formed on the back surface of the substrate. Or the structure in which the n electrode 19 which contacts the n side semiconductor layer 11 is formed in the semiconductor layer 20 side of a board | substrate may be sufficient.

  In the semiconductor element of the present invention, since the region of the semiconductor layer to which the electrode 15 is connected is only the top surface of the ridge, current leakage when the electrode contacts the side surface of the ridge can be avoided. In addition, since the tip portion 16a of the protective film 16 is disposed at a position higher than the ridge 14, there is no problem that the electrode wraps around the side surface of the ridge when the electrode is formed or when the semiconductor element is operated. The electrode 15 covers the tip of the protective film 16, but does not extend to a region opposite to the ridge 14. The pad electrode 18 is in contact with the surface of the electrode 15 having a concave shape in cross section, and the adhesion between the pad electrode 18 and the electrode 15 is improved. The pad electrode 18 also covers the outer surface of the protective film.

  Furthermore, in the present invention, since the electrode can be formed after forming the protective film, the material of the protective film is not limited, and the film quality of the protective film is stabilized and uniformed, and the film thickness is uniform. Can be achieved. As a result, it is possible to stabilize the refractive index difference with the semiconductor layer due to the change in the material of the protective film, and to operate a highly reliable semiconductor element.

  A method for manufacturing a semiconductor device of the present invention will be described below with reference to steps (a) to (d) in FIG. 3 and steps (e) and (f) in FIG. In the method for manufacturing a semiconductor device of the present invention, in step (a), first, a semiconductor layer including an active layer is formed on a substrate. In this semiconductor layer, an n-side semiconductor layer, an active layer, and a p-side semiconductor layer are stacked in this order on a substrate.

The substrate is preferably sapphire, spinel (MgA1 ₂ O ₄ ), silicon carbide, silicon, ZnO, GaAs, or a nitride substrate (GaN, AlN, etc.).

The thickness of the substrate is, for example, about 50 μm to 10 mm. Here, the nitride substrate is formed by vapor phase growth method such as MOVPE, MOCVD method (metal organic chemical vapor deposition method), HVPE method (halide vapor phase growth method), or hydrothermal synthesis method for crystal growth in a supercritical fluid. , High pressure method, flux method, melting method and the like. A commercially available product may also be used. For example, the substrate is more preferably a nitride substrate having an off angle of about 0.03 to 10 ° on the first main surface and / or the second main surface. Further, the number of dislocations per unit area may be 1 × 10 ⁷ / cm ² or less.

Among the n-side semiconductor layer, the active layer, and the p-side semiconductor layer, examples of the n-side and p-side semiconductor layer include III-V group nitride semiconductor layers such as AlN, GaN, AlGaN, AlInGaN, and InN. Among these, a nitride semiconductor layer containing Al is suitable. Specifically, In _y Al _z Ga _1-yz N (0 ≦ y, 0 ≦ z, y + z ≦ 1), in particular, gallium nitride series such as Al _x Ga _1-x N (0 <x <1) A compound semiconductor layer is preferred. These semiconductor layers have a single layer or a stacked structure. Moreover, the structure which has a superlattice structure may be sufficient.

  The n-side semiconductor layer has a clad layer, and may further have a light guide layer and a crack prevention layer between the clad layer and an active layer described later. The p-side semiconductor layer has a clad layer and a contact layer, and may have a configuration having a cap layer and a light guide layer between an active layer and a clad layer, which will be described later.

The n-side semiconductor layer and the p-side semiconductor layer can be formed using a method similar to that of the nitride substrate. The n-side semiconductor layer is doped with an n-side impurity such as Si or Ge, and the p-side semiconductor layer is doped with a p-side impurity such as Mg or Zn, thereby having conductivity. An example of the doping concentration is about 1 × 10 ^{16 to} 5 × 10 ²⁰ cm ⁻³ .

  The active layer may be either a multiple quantum well structure or a single quantum well structure. The film thickness of the active layer is suitably about 10 to 300 nm, for example. In particular, in the case of a quantum well structure, the film thickness of the well layer and the number of well layers are not particularly limited. For example, the film thickness is in the range of about 1 to 30 nm, so that Vf, threshold current density Can be reduced. It is preferable to keep the thickness of the active layer low by setting the thickness of the well layer to 10 nm or less. As a film thickness of a barrier layer, it is 50 nm or less, for example, Preferably, the range of about 1-30 nm is mentioned. The range of the oscillation wavelength of the active layer is not particularly limited, but when a nitride semiconductor layer is used, it is, for example, 350 nm or more and 650 nm or less.

Next, a mask layer having a predetermined shape is formed on the semiconductor layer of the wafer in which the semiconductor layers are stacked on the substrate.
First, a mask layer 21 and a resist layer are sequentially formed on the semiconductor layer. The resist layer is patterned into a predetermined shape, and further the mask layer is patterned into the same shape using the resist layer as a mask. After patterning the mask layer, the resist layer can be removed to form a mask layer having a predetermined shape. Here, the material of the mask layer is SiO ₂ or the like. This mask layer can be diverted with other known mask materials. The film thickness of a mask layer is not specifically limited, For example, it is suitable to set it as about 100-1000 nm, and about 100-500 nm is preferable. The mask layer can be formed by a known method such as CVD, sputtering, or vapor deposition.

Next, in step (b), a ridge is formed on the semiconductor layer. A part of the p-side semiconductor layer on the surface of the semiconductor layer is removed from the opening of the mask layer to form a ridge.
The method for removing a part of the p-side semiconductor layer is not particularly limited, and either wet etching or dry etching may be used. Specifically, in consideration of the material of the semiconductor layer, it is preferable to select and remove an etchant that has a high selectivity with the mask layer. The size of the ridge substantially corresponds to the size of the mask layer, but the width of the bottom surface side is wide and the stripe width decreases as it approaches the top surface. It may be a shape in which these are combined. The width of the ridge is suitably about 1.0 μm to 10.0 μm, for example, and preferably about 1.2 μm to 2.5 μm. The height of the ridge can be adjusted as appropriate depending on the film thickness of the p-side semiconductor layer, and examples thereof include about 0.1 to 2 μm, and further about 0.2 to 1 μm.

Next, in step (c), the protective film 16 is formed at least in a region extending from the ridge bottom region 14a to the mask layer 21 on the ridge top surface. The protective film 16 is formed not only on the ridge bottom surface region 14a and the ridge side surface 14b but also on the region where the mask layer 21 is formed on the ridge top surface 14c. This protective film ensures insulation between the upper surface of the p-side semiconductor layer, which is the ridge bottom region 14a, and the side surface of the ridge, and also ensures a difference in refractive index with respect to the p-side semiconductor layer to control light leakage from the active layer. Has the function to obtain. Further, the semiconductor element of the present invention can suppress light absorption at the upper part on both sides of the ridge by having the tip 16a of the protective film formed in a later step. The protective film is not particularly limited as long as it is a material having such functions as insulation. For example, Si, Mg, Al, Hf, Nb, Zr, Sc, Ta, Ga, Zn, Y, B, Ti and their oxides, nitrides (eg, AlN, AlGaN, BN, etc.), fluorides, etc. Compounds. The protective film may be a single film or a multilayer film in which a plurality of protective films are combined. Of these, a film made of SiO ₂ or ZrO ₂ is preferable. These films can be formed by methods known in the art such as sputtering, vacuum deposition, and vapor deposition. The film thickness is, for example, about 20 to 500 nm, and about 50 to 100 nm is appropriate.

Next, in step (d), a second mask layer 22 is formed on the protective film other than the ridge upper surface 14c. Here, it is preferable to pattern-form a resist layer on the second mask. The second mask is a resist pattern in which a protective layer is exposed at a position corresponding to the ridge by forming a resist layer on the protective film 16 and then etching back the resist layer. This second mask covers the protective film 16 formed on the ridge bottom region 14a and the ridge side surface 14b.
The upper surface of the second mask is set lower than the upper surface of the protective film 16 formed on the ridge upper surface 14c as described above by appropriately selecting the etch back time, the type of etchant, and the like. And higher than the ridge upper surface 14c. Here, the height of the upper surface of the second mask is higher than the upper surface of the ridge 14c and lower than the upper surface of the protective film 16 formed on the upper surface of the ridge upper surface 14c.

  As a method for removing the second mask, an appropriate etchant may be selected in consideration of the resist pattern material and the like, and may be removed using either wet etching or dry etching. For example, nitric acid, hydrofluoric acid, dilute hydrochloric acid, dilute nitric acid, sulfuric acid, hydrochloric acid, acetic acid, hydrogen peroxide and other acids alone or a mixture of two or more, alkaline solutions such as ammonia alone or ammonia and hydrogen peroxide, etc. An appropriate etchant such as a mixed solution of the above and various surfactants is used. Examples of the method for removing the second mask remaining in unnecessary portions include known methods such as immersion, ultrasonic treatment, or a combination thereof.

  Next, in the step (e), the mask layer and the protective film on the top surface of the ridge are removed. By removing the protective film on the top surface of the ridge, the tip 16a of the protective film is formed at a position higher than the ridge. This also exposes the ridge upper surface 14c.

  The front end portion 16a of the protective film is formed by removing the mask layer and the protective film on the upper surface of the ridge here. The tip 16a of the protective film is formed by extending the protective film formed on the ridge side surface 14b toward the top surface of the ridge. The height of the tip 16a of the protective film can be adjusted by the thickness of the mask layer. The height of the tip 16a of the protective film is preferably about 50 nm to 500 nm from the ridge upper surface 14c. If the height of the tip 16a of the protective film is within this range, light absorption on the top surface of the ridge is suppressed. In addition, the adhesion between the electrode and the pad electrode is improved. Furthermore, when the height of the tip 16a of the protective film is 100 nm to 200 nm from the ridge upper surface 14c, the adhesion between the protective film and the electrode is maintained well.

  The method for removing the mask layer 21 and the protective film formed thereon is not particularly limited, but a lift-off method can be used. The lift-off can be appropriately selected depending on, for example, the type of the mask layer and the protective film, and for example, an acid such as nitric acid, hydrofluoric acid, sulfuric acid, hydrochloric acid, acetic acid, hydrogen peroxide, or a mixture of two or more kinds. It is suitable to use an appropriate etchant such as a liquid, an alkaline solution such as ammonia alone, a mixed liquid of ammonia and hydrogen peroxide, or various surfactants. In addition, a known method such as immersion, rinsing, ultrasonic treatment, or a combination thereof can be used.

  Next, in step (f), an electrode material film is formed on the ridge upper surface 14c and the tip 16a of the protective film. Here, the electrode 15 is formed on the upper surface of the ridge exposed after the removal step of the step (e) and the tip of the protective film. Here, the width of the electrode is the same as the width of the ridge.

As an electrode material, what is normally used as an electrode can be used. For example, a single layer film or a laminated film such as a metal, an alloy, or a conductive oxide film can be given. The thickness of these electrode materials is suitably about 50 to 1000 nm, and preferably about 100 to 500 nm. Specifically, Ni (film thickness: about 5 to 20 nm) and Au (film thickness: about 50 to 300 nm) from the semiconductor layer side, and Ni—Au—Pt, Ni including this two layer structure _{-Au-Rh, Ni-Au-} RhO 2, Ni-Au-Pd, Ni-Au-Ir, there is Ni-Au-Ru or the like. Other examples include a three-layer structure such as Ni—ITO—Pt, Ni—ITO—Rh, Pd—Pt—Au, Pd—Pt—Rh, Pd—Pt—Ir, and Rh—Ir—Pt. These electrode material films can be formed by a known method such as CVD, sputtering, or vapor deposition. The film thickness of the electrode material film is not particularly limited. For example, the sheet resistance can be lowered by setting the thickness to about 50 nm or more.

Furthermore, in an arbitrary stage after the step (f), the pad electrode 18 is formed on the semiconductor element and on the protective film 16 and the electrode 15.
The pad electrode is preferably a laminated film made of a metal such as Ni, Ti, Au, Pt, Pd, or W. Specifically, a film formed in the order of W—Pd—Au or Ni—Ti—Au and Ni—Pd—Au from the p-electrode side can be given. The film thickness of the pad electrode is not particularly limited, but the film thickness of the final layer of Au is preferably about 100 nm or more. The shape of the pad electrode is not particularly limited.

  In the method for manufacturing a semiconductor element of the present invention, it is preferable to polish the second main surface of the substrate at any stage, for example, before forming the n-side electrode. Any method known in the art can be used as the method for polishing the substrate.

  Furthermore, it is preferable to form the n-side electrode partially or entirely on the second main surface of the substrate before and after the formation of the p-side electrode described above. The n-side electrode can be formed by, for example, sputtering, CVD, vapor deposition, or the like. For forming the n-side electrode, it is preferable to use a lift-off method, and after forming the n-side electrode, it is preferable to perform annealing at about 300 ° C. or higher. As the n-side electrode, for example, the total film thickness may be about 1 μm or less, and the material of the n-side electrode is not particularly limited. For example, V (film thickness 10 nm) −Pt (film thickness) from the substrate side. 200 nm) -Au (film thickness 300 nm) in this order. In addition, Ti (15 nm) -Pt (200 nm) -Au (300 nm), Ti (10 nm) -Al (500 nm), Ti (6 nm) -Pt (100 nm) -Au (300 nm), Ti (6 nm) -Mo (50 nm) -Pt (100 nm) -Au (210 nm) and the like are exemplified.

  A metallized electrode may be formed on the n-side electrode. The metallized electrodes are, for example, Ti—Pt—Au— (Au / Sn), Ti—Pt—Au— (Au / Si), Ti—Pt—Au— (Au / Ge), Ti—Pt—Au—In, It can be formed of Au—Sn, In, Au—Si, Au—Ge, or the like. The film thickness of the metallized electrode is not particularly limited. When the ohmic characteristics are maintained only with the metallized electrode, the n-side electrode can be omitted.

  Optionally, for example, the second protective film 17 may be formed on the protective film 16 after the step (f). The second protective film can be formed by a method known in the art, and can be selected from the same materials as the protective film described above.

Optionally, a resonator surface is formed in the semiconductor layer. The resonator surface can be formed by a method known in the art by etching or cleavage. Further, it is preferable to form a dielectric film on the obtained resonator surface, that is, on the light reflecting side and / or the light emitting surface of the resonator surface at an arbitrary stage. The dielectric film is preferably a single layer film or a multilayer film made of SiO ₂ , ZrO ₂ , TiO ₂ , Al ₂ O ₃ , Nb ₂ O ₅ , AlN, AlGaN or the like.
Furthermore, a semiconductor element chip can be obtained by dividing in the resonator direction. This division can be formed by forming a division auxiliary groove at an arbitrary stage and scribing using the division auxiliary groove.

  According to the method for manufacturing a semiconductor element of the present invention, a highly reliable semiconductor element can be manufactured by a simple process without being restricted by the material of the protective film and the electrode. In other words, by minimizing the number of etch-back processes that are difficult to control in normal semiconductor processes, each process can be controlled with high precision, and the manufacturing yield of semiconductor elements can be improved by simple processes. Can be made. Further, the mass productivity of the semiconductor element is improved by the manufacturing method of the present invention.

Examples of the semiconductor element of the present invention will be described below, but the present invention is not limited to the following examples. The semiconductor element here will be described using a semiconductor laser element.
Example 1
In the semiconductor laser device of this example, as shown in FIG. 1, an n-side semiconductor layer 11, an active layer 12, and a p-side semiconductor layer 13 are laminated in this order on a GaN substrate 10 having a C plane as a growth surface. A semiconductor layer is formed, and a ridge 14 is formed on the surface of the p-side semiconductor layer 13.
A p-side electrode 15 is in ohmic contact with the ridge 14. The electrode 15 is in contact with the p-side semiconductor layer 13 only on the top surface of the ridge 14, but is formed so as to cover the tip 16 a of the protective film as will be described later. Wider than.

In this semiconductor element, a protective film 16 extending from the ridge bottom surface region 14a, which is the surface of the p-side semiconductor layer 13, to the ridge side surface 14b and extending to a region higher than the ridge top surface is formed. This protective film is not formed on the upper surface of the ridge, but has a tip 16a extending to a region higher than the upper surface of the ridge. An electrode 15 is formed on the tip 16a of the protective film and on the ridge upper surface 14c. Since there is a height difference between the tip 16a of the protective film covered by the electrode 15 and the ridge upper surface 14c, the contact area of the electrode is widened by the step formed by the height difference.
A second protective film 17 is formed on the side surface of the semiconductor element. Further, although not shown, a multilayer dielectric film made of Al ₂ O ₃ and ZrO ₂ is formed on the resonator surface of the semiconductor layer.
A p-side pad electrode 18 is formed so as to cover the electrode 15 and the protective film 16.

Such a semiconductor laser device can be formed by the following manufacturing method.
(Ridge formation)
First, the GaN substrate 10 is prepared. Next, the semiconductor layer 20 in which the n-side semiconductor layer 11, the active layer 12, and the p-side semiconductor layer 13 are stacked in this order is formed on the substrate 10. FIG. 3A shows only the semiconductor layer 20.
Thereafter, a SiO ₂ film is formed as a mask layer 21 with a film thickness of 0.3 μm on almost the entire surface of the p-side semiconductor layer 13 by a PVD apparatus. A resist pattern having a predetermined shape is formed thereon. The width of this resist pattern is 2.0 μm.
Subsequently, the SiO ₂ film is etched using this resist pattern as a mask. An RIE (reactive ion etching) apparatus is used as an etching apparatus, and CHF ₃ is used as an etching gas. Here, the width of the mask layer is a ridge width described later. Thereafter, the resist pattern is removed.

  Next, as shown in FIG. 3B, a ridge is formed on the surface of the stacked semiconductor layer 20. Specifically, the ridge 14 is formed on the surface of the p-side semiconductor layer 13 that is the upper layer of the semiconductor layer 20. Here, a chlorine-based gas is used as an etching gas using an RIE apparatus. By etching the p-side semiconductor layer 13 exposed at the opening of the mask layer 21, a stripe-shaped ridge 14 having a width of about 2.0 μm and a height of about 0.5 μm is formed.

(Formation of protective film)
Thereafter, as shown in FIG. 3C, a protective film 16 is formed to cover the upper surface of the mask layer 21 from the bottom surface region of the ridge. The protective film 16 is formed by forming a SiO ₂ film with a film thickness of 100 nm using a PVD apparatus.

  Next, as shown in FIG. 3D, a second mask layer 22 is formed except on the p-side semiconductor layer 13 on which the ridge 14 is formed. Here, a resist layer is first formed on the entire surface of the protective film 16 as the second mask layer 22. After that, by etching back using oxygen, an opening is formed in the second mask layer 22 at a position corresponding to the ridge 14, and the upper surface of the second mask layer 22 is higher than the ridge upper surface 14c. It is formed at a high position. The film thickness of the second mask layer 22 after the etch back is about 0.5 μm.

  Next, as shown in FIG. 4E, the mask layer 21 on the ridge upper surface 14c and the protective film 16 formed thereon are removed using a lift-off method. As a result, the upper surface of the ridge is exposed, and the leading end portion 16a of the protective film located higher than the upper surface of the ridge is also formed. In this lift-off method, a BHF solution is used as a stripping solution. Here, the height of the tip 16a of the protective film is 0.1 μm from the ridge upper surface 14c. Since the tip 16a of the protective film is positioned higher than the ridge upper surface, light absorption of the electrode on the ridge side surface is also suppressed.

(Formation of electrodes)
Next, as shown in FIG. 4F, the electrode 15 is formed on the ridge 14 and the tip 16a of the protective film. The electrode 15 is formed in the order of Ni (10 nm) -Au (100 nm) -Pt (100 nm) from the lower side on the second mask layer, the tip of the protective film, and the ridge. Next, by removing the second mask layer, the electrode formed thereon is also removed at the same time. The method for removing the second mask layer is a lift-off method using a stripping solution, and simultaneously with the second mask layer, the electrode 15a on the second mask layer is also removed.
Since the electrode 15 is in contact with the semiconductor layer only at the ridge upper surface 14c, current leakage does not occur.

  Thereafter, the p-side pad electrode 18, the second protective film 17, the n-side electrode 19 and the like are formed on the back surface of the substrate 10, whereby the semiconductor element shown in FIG. 1 can be formed.

In this way, since the electrodes are connected only on the top surface of the ridge, current leakage when the electrodes contact the side surfaces of the ridge can be avoided. Further, light absorption by the electrode can be avoided, and the laser light extraction efficiency can be improved.
Further, when the electrode is wider than the ridge, the contact area with the pad electrode usually formed thereon can be increased, and the power supply can be improved.
In addition, a semiconductor element having stable characteristics can be easily manufactured by a simple process.

Example 2
In the semiconductor laser device of this embodiment, a SiO ₂ film having a thickness of 0.5 μm is formed as the mask layer 21. Further, a semiconductor laser element is manufactured substantially in the same manner as the semiconductor laser element of Example 1 except that the height of the tip 16a of the protective film is 0.2 μm.
Also in this embodiment, the same effect as in the first embodiment can be obtained.

Example 3
In the semiconductor laser device of this embodiment, a SiO ₂ film having a thickness of 0.4 μm is formed as the mask layer 21. Further, a semiconductor laser element is manufactured in substantially the same manner as the semiconductor laser element of Example 1 except that the height of the tip 16a of the protective film is 0.15 μm.
Also in this embodiment, the same effect as in the first embodiment can be obtained.

Example 4
The semiconductor laser device of this example is substantially the same as the semiconductor laser device of Example 1 except that Ni (10 nm) -Au (100 nm) -Rh (50 nm) is formed in order from the ridge 14 side as the electrode 15. A semiconductor laser device is manufactured.
Also in this embodiment, the same effect as in the first embodiment can be obtained.

  The semiconductor element of the present invention can be used for, for example, a light emitting element such as a semiconductor laser and a light emitting diode, an electronic device such as a transistor, a light receiving element, a solar cell, and the like. The use is, for example, an illumination light source, a display light source, an optical disk light source, an optical communication system light source, a printing machine light source, an exposure light source, a measuring instrument light source, a bio-related excitation light source, or the like.

10 substrate 11 n-side semiconductor layer 12 active layer 13 p-side semiconductor layer 14 ridge 14a ridge bottom surface region 14b ridge side surface 14c ridge top surface 15 electrode 16 protective film 16a protective film tip 17 second protective film 18 p-side pad electrode 19 n Side electrode 20 Semiconductor layer 21 Mask layer 22 Second mask layer

Claims (2)

A method for manufacturing a semiconductor device, comprising:
(A) stacking a semiconductor layer on a substrate and forming a mask layer having a predetermined shape on the semiconductor layer;
(B) removing a part of the semiconductor layer from the opening of the mask layer to form a ridge;
(C) forming a protective film at least in a region extending from the bottom surface region of the ridge to the mask layer on the top surface of the ridge;
(D) forming a second mask layer on the protective film other than the top surface of the ridge so that the top surface of the second mask layer is higher than the top surface of the ridge;
(E) removing the mask layer and the protective film on the upper surface of the ridge to expose the upper surface of the ridge and forming the tip of the protective film at a position higher than the ridge;
(F) forming an electrode material film on the top surface of the ridge, the tip of the protective film, and the second mask;
(G) forming an electrode material film only on the top surface of the ridge and the tip of the protective film by removing the second mask layer, and a method for manufacturing a semiconductor device. In step (d), after forming a second mask layer, The method according to claim 1 for patterning a mask layer of the second in a region other than the top surface of the ridge by etching back.

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