JP2010062300A - Nitride semiconductor element and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nitride semiconductor element, which prevents the exfoliation of an insulating film of a ridge sidewall portion and improves a far field pattern, and to provide a method of manufacturing the nitride semiconductor element. <P>SOLUTION: The nitride semiconductor element 1 and the method of manufacturing the nitride semiconductor element are provided. The nitride semiconductor element 1 includes: a GaN-based semiconductor substrate 10; n-type semiconductor layers (12, 14, 16) that are placed on the GaN-based semiconductor substrate 10; an InGaN active layer 18 that is placed on the n-type semiconductor layers (12, 14, 16) and contains In; a p-type GaN guide layer 22 that is placed on the InGaN active layer 18; a p-type superlattice cladding layer 26 that is placed on the p-type GaN guide layer 22 and includes a ridge shape; an adhesion layer 23 that is placed on a sidewall of the ridge shape of the p-type superlattice cladding layer 26 and is formed of a metal layer or an elemental semiconductor layer; and an insulating film 24 that is placed on the adhesion layer 23. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a nitride semiconductor device and a manufacturing method thereof, and more particularly to a nitride semiconductor device having an improved far field pattern and a manufacturing method thereof.

  A technique for preventing peeling of an ohmic electrode formed in a ridge structure of a compound semiconductor laser structure having a ridge structure has already been disclosed (see, for example, Patent Documents 1 to 3). In each of Patent Documents 1 to 3, an insulating layer and an ohmic electrode are used to prevent the ohmic electrode from peeling off in an insulating layer formed on the side wall portion of the ridge structure and an ohmic electrode formed on the insulating layer. A peeling prevention layer made of a metal layer is provided between the electrodes.

  In the compound semiconductor laser structure, an insulating film is formed on a ridge-shaped compound semiconductor layer, and a refractive index difference is provided with respect to the compound semiconductor layer, thereby obtaining a light confinement effect.

  However, when forming an insulating film into a ridge shape, if a film forming apparatus having film forming characteristics having directivity is used, there is a drawback that the insulating film is peeled off due to insufficient coating on the ridge side wall. . An example of a film forming apparatus having a directivity film forming characteristic is an ECR (Electron Cyclotron Resonance) sputtering apparatus.

Conventionally, since a reactive plasma film forming apparatus having directivity is used, the reactivity of the ridge side wall is poor, so that the quality of the formed insulating film is poor (for example, the amount of Zr and O in ZrO ₂ ). Is deviated from the stoichiometric composition), which caused peeling of the insulating film on the side wall.

  If the insulating film is peeled off, the balance of light confinement is lost, leading to a failure in the initial laser characteristics such as the beam shape being lost.

A schematic cross-sectional structure of a ridge portion of a nitride semiconductor device according to a conventional example includes, for example, a p-type GaN guide layer 22 and a p-type superlattice disposed on the p-type GaN guide layer 22 as shown in FIG. The clad layer 26, the p-type GaN contact layer 28 disposed on the p-type superlattice clad layer 26, the p-type GaN guide layer 22, and the sidewalls of the p-type superlattice clad layer 26 and the p-type GaN contact layer 28 And the p-side ohmic electrode 30 formed on the insulating film 24 and the p-type GaN contact layer 28. In the SEM photograph of the ridge portion of the nitride semiconductor device according to the conventional example, for example, as shown in FIG. 9, it is observed that the insulating film 24 is peeled off due to insufficient coating on the ridge side wall. The relationship between the beam intensity of the nitride semiconductor device according to the conventional example and the beam divergence angles in the horizontal direction and the vertical direction is expressed, for example, as shown in FIG. In particular, the symmetry of the horizontal far field pattern (FFP) is poor.
JP 2006-13331 A JP 2006-128389 A JP 2006-128622 A

  An object of the present invention is to provide a nitride semiconductor device having an improved far field pattern by preventing the insulating film on the ridge side wall from being peeled off, and a method for manufacturing the same.

  According to one aspect of the present invention for achieving the above object, a GaN-based semiconductor substrate, an n-type semiconductor layer disposed on the GaN-based semiconductor substrate, and In disposed on the n-type semiconductor layer are formed. Including an active layer, a p-type semiconductor layer disposed on the active layer, a compound semiconductor layer disposed on the p-type semiconductor layer and including a ridge shape, and disposed on a ridge-shaped sidewall of the compound semiconductor layer There is provided a nitride semiconductor device comprising the adhesive layer formed and an insulating film disposed on the adhesive layer.

  According to another aspect of the present invention, a step of forming an n-type semiconductor layer on a GaN-based semiconductor substrate, a step of forming an active layer containing In on the n-type semiconductor layer, and p on the active layer A step of forming a semiconductor layer, a step of forming a compound semiconductor layer including a ridge shape on the p-type semiconductor layer, a step of forming an adhesion layer on a ridge-shaped side wall of the compound semiconductor layer, and the adhesion There is provided a method of manufacturing a nitride semiconductor device including a step of forming an insulating film on a layer.

  ADVANTAGE OF THE INVENTION According to this invention, the peeling of the insulating film of a ridge side wall part can be prevented, and the nitride semiconductor element which improved the far field pattern, and its manufacturing method can be provided.

  Next, embodiments of the present invention will be described with reference to the drawings. In the following, the same members or elements are denoted by the same reference numerals to avoid duplication of explanation, and the explanation is simplified. It should be noted that the drawings are schematic and different from the actual ones. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  The following embodiments exemplify apparatuses and methods for embodying the technical idea of the present invention. In the embodiments of the present invention, the arrangement of each component is as follows. Not specific. Various modifications can be made to the embodiment of the present invention within the scope of the claims.

[First embodiment]
The nitride semiconductor device 1 according to the first embodiment of the present invention includes a GaN-based semiconductor substrate 10 and a regrowth layer 11 disposed on the GaN-based semiconductor substrate 10 as schematically shown in the bird's-eye view of FIG. A crack prevention layer 12 disposed on the regrowth layer 11, an n-type superlattice cladding layer 14 disposed on the crack prevention layer 12, and an n-type GaN disposed on the n-type superlattice cladding layer 14. Guide layer 16, InGaN active layer 18 disposed on n-type GaN guide layer 16, electron block layer 20 disposed on InGaN active layer 18, and p-type GaN guide disposed on electron block layer 20 A layer 22.

  Furthermore, the nitride semiconductor device 1 according to the first embodiment is arranged on the p-type superlattice cladding layer 26 arranged in stripes on the p-type GaN guide layer 22 and on the p-type superlattice cladding layer 26. P-type GaN contact layer 28.

  Furthermore, the nitride semiconductor device 1 according to the first embodiment includes an adhesion layer 23 disposed on the p-type GaN guide layer 22, the p-type superlattice cladding layer 26, and the p-type GaN contact layer 28. And an insulating film 24 disposed on the adhesion layer 23.

  The insulating film 24 is opened in the upper surface of the p-type GaN contact layer 28 arranged in a stripe shape. The p-type GaN contact layer 28 is in contact with the p-side ohmic electrode 30 in the opening opened in the window.

  Furthermore, in the nitride semiconductor device according to the first embodiment, the p-side ohmic electrode 30 has the sidewalls of the p-type superlattice cladding layer 26 and the p-type GaN contact layer 28 arranged in a stripe shape with the insulating film 24 interposed therebetween. Are arranged in a stripe shape along the laser stripe 80.

  Furthermore, in nitride semiconductor device 1 according to the present embodiment, p is formed on insulating film 24 covering the nitride semiconductor laser body and on p-side ohmic electrode 30 arranged in stripes along laser stripe 80. The n-side electrode 40 is disposed on the GaN-based semiconductor substrate 10 on the back side facing the surface on which the side electrode 32 is disposed and the p-side electrode 32 is disposed.

  The bird's-eye view of FIG. 1 shows a view in which the laser element is cleaved at a cleavage plane and the element is cut in a direction parallel to the resonance plane.

  As shown in FIG. 1, the nitride semiconductor device according to the present embodiment includes a GaN-based semiconductor substrate 10, an n-type semiconductor layer (12, 14, 16) disposed on the GaN-based semiconductor substrate 10, and an n-type semiconductor layer. Active layer 18 containing In arranged on the p-type semiconductor layer (12, 14, 16), p-type semiconductor layer (20, 22) arranged on the active layer 18, and p-type semiconductor layer (20, 22) The compound semiconductor layer (26, 28) including the ridge shape, the adhesion layer 23 disposed on the ridge-shaped sidewall of the compound semiconductor layer (26, 28), and the adhesion layer 23. And an insulating film 24.

  The adhesion layer 23 is made of a metal layer or an element semiconductor layer.

  The metal layer constituting the adhesion layer 23 is made of any one of Zr, Al, Ti, Ta, for example.

  Alternatively, the element semiconductor layer constituting the adhesion layer 23 may be made of Si, for example.

  The thickness of the adhesion layer 23 is 10 nm or less.

The insulating film 24 is made of any one of ZrO ₂ film, SiO ₂ film, SiN film, Al ₂ O ₂ film, AlN film, TiO ₂ film, and Ta ₂ O ₅ film.

Further, the p-side ohmic electrode 30 and the p-side electrode 32 are made of, for example, Pd / Au. The n-side electrode 40 is made of, for example, Al / Ti / Au.

  The schematic cross-sectional structure of the ridge portion of the nitride semiconductor device according to the first embodiment includes a p-type GaN guide layer 22 and a p-type disposed on the p-type GaN guide layer 22, as shown in FIG. Superlattice cladding layer 26, p-type GaN contact layer 28 disposed on p-type superlattice cladding layer 26, p-type GaN guide layer 22, and p-type superlattice cladding layer 26 and p-type GaN contact layer 28 The adhesion layer 23 formed on the sidewall, the insulating film 24 disposed on the adhesion layer 23, the insulating film 24, and the p-side ohmic electrode 30 formed on the insulating film 24 and the p-type GaN contact layer 28. With.

  The SEM photograph of the ridge portion of the nitride semiconductor device according to the first embodiment is shown in FIG. 3, for example, by covering the insulating film 24 with the adhesion layer 23, the adhesion to the ridge sidewall. As a result, the insulating film 24 was not peeled off.

  The relationship between the beam intensity of the nitride semiconductor device according to the first embodiment and the beam divergence angles in the horizontal direction and the vertical direction is expressed, for example, as shown in FIG. Compared with the conventional structure shown in FIG. 10, the symmetry of the FFP in the horizontal direction is improved, and the half-value width of the FFP in the vertical direction is narrow.

  In the nitride semiconductor device according to the first embodiment, the adhesion layer 23 made of an ultrathin metal layer or elemental semiconductor layer that does not affect the light confinement is used as the compound semiconductor layer (26, 28). By forming between the insulating films 24, the adhesion between the insulating film 24 and the compound semiconductor layers (26, 28) can be improved. Thereby, it is possible to suppress the deterioration of the initial laser characteristics such as the beam shape being broken.

  In the nitride semiconductor device according to the first embodiment, a very thin high-quality film (a stoichiometric composition is a general value, or a single metal, a semiconductor film) is sandwiched, and the high-quality film is stacked. By selecting a film having the same structure as the element constituting the insulating film 24, a film with poor film quality does not exist at the interface with the compound semiconductor layer (26, 28), and adhesion is improved.

  In the nitride semiconductor device according to the first embodiment, this high-quality film is formed by sputtering a trace amount of the target of the reactive film forming apparatus with Ar plasma. Even if this method is changed to vapor deposition or CVD (Chemical Vapor Deposition), the effect of the present invention is the same.

(Production method)
The method for manufacturing a nitride semiconductor device according to the first embodiment includes a step of forming an n-type semiconductor layer (12, 14, 16) on a GaN-based semiconductor substrate 10, and an n-type semiconductor layer (12, 14, 16) a step of forming an active layer 18 containing In, a step of forming a p-type semiconductor layer (20, 22) on the active layer 18, and a ridge shape on the p-type semiconductor layer (20, 22). Forming the compound semiconductor layer (26, 28), forming the adhesion layer 23 on the ridge-shaped sidewall of the compound semiconductor layer (26, 28), and forming the insulating film 24 on the adhesion layer 23. Process.

  The step of forming the adhesion layer includes a step of sputtering a metal layer or an element semiconductor layer from the target by Ar plasma irradiation.

  In the step of forming the insulating film 24 on the ridge-shaped compound semiconductor layers (26, 28) during the manufacturing process of the nitride semiconductor device according to the first embodiment, the insulating film is formed before the insulating film 24 is formed. Ar plasma is irradiated in the film forming apparatus. By this Ar plasma irradiation, for example, a very small amount of metal film is sputtered from the target 44 in the insulating film forming apparatus, so that the adhesion layer 23 is formed between the insulating film 24 and the compound semiconductor layer (26, 28). For example, a metal layer can be formed. Thereafter, the insulating film 24 is formed, and the insulating film can be formed with the metal layer serving as the adhesion layer 23 interposed therebetween.

  Further, by using an element semiconductor (for example, Si) as a target at the time of plasma irradiation, an element semiconductor such as Si can be formed as the adhesion layer 23.

  Since Ar plasma irradiation is not a process of positively forming a film (no high frequency is applied to the target 44), a very small amount of metal layer can be formed. For example, since the film is formed with a thickness of about 30 nm by 30 minutes of plasma irradiation, it can be controlled at a film formation rate of 1 nm / min.

  As an insulating film forming apparatus 54 applied to the method for manufacturing a nitride semiconductor device according to the first embodiment, a schematic cross-sectional structure of an ECR sputtering apparatus is as shown in FIG. (Microwave: 2.45 GHz) 52, a vacuum exhaust unit 46, an ECR generating magnet 48, a target 44, an ECR plasma 50, and a sample mounting unit 42.

  In the nitride semiconductor device manufacturing method according to the first embodiment, the Auger depth direction analysis result of the sample irradiated with Ar plasma for 30 minutes is expressed as shown in FIG. The vertical axis represents atomic concentration (%), and the horizontal axis represents sputtering time (minutes). An example in which Zr is used as the target 44 is shown.

The sputtering rate is about 6 nm / min, for example, in terms of SiO ₂ . Therefore, since the Zr signal continues from the sample surface direction to about 5 minutes, it can be read that the film is formed to be about 30 nm.

  A method for manufacturing the nitride semiconductor device according to the first embodiment will be described in detail below.

(A) A wafer having a GaN-based semiconductor substrate 10 as a main surface is set in a reaction vessel of an MOCVD apparatus, and GaN doped with Si at 1 × 10 ¹⁸ / cm ³ on the GaN-based semiconductor substrate 10 at 1050 ° C. The regrowth layer 11 to be formed is grown by 2 μm.

(B) Subsequently, a crack prevention layer 12 made of InGaN doped with Si at 5 × 10 ¹⁸ / cm ^{3 is} grown on the regrowth layer 11 to a thickness of 500 Å. The crack prevention layer 12 can be prevented from being cracked in the Al mixed crystal by being grown with an n-type nitride semiconductor containing In, preferably InGaN.

(C) Subsequently, a first layer made of n-type Al _0.1 Ga _0.9 N doped with 5 × 10 ¹⁸ / cm ^{3 of} Si, 20 angstroms, and a second layer made of undoped GaN, alternating with 20 angstroms An n-type superlattice clad layer 14 having a superlattice structure with a total film thickness of 0.4 μm formed by laminating 100 layers is formed on the crack prevention layer 12. The n-type superlattice clad layer 14 has a carrier and light confinement effect, and is preferably a superlattice layer containing AlGaN having a band gap higher than that of GaN and a refractive index lower than that of GaN. Thus, a clad layer having good crystallinity without cracks can be formed.

(D) Subsequently, an n-type GaN guide layer 16 made of n-type GaN doped with Si at 5 × 10 ¹⁸ / cm ³ is grown on the n-type superlattice cladding layer 14 to a thickness of 0.1 μm. The n-type GaN guide layer 16 functions as a light guide layer for the InGaN active layer 18.

(E) Subsequently, a total film formed by alternately laminating a well layer made of In _0.2 Ga _0.8 N, 25 Å, a barrier layer made of In _0.05 Ga _0.95 N, and 50 Å on the n-type GaN guide layer 16. An InGaN active layer 18 having a multiple quantum well structure (MQW) having a thickness of 175 Å is grown.

(F) Subsequently, an electron blocking layer 20 made of p-type Al _0.1 Ga _0.9 N doped with 1 × 10 ²⁰ / cm ^{3 of} Mg and having a band gap larger than that of the p-side light guide layer is formed on the InGaN active layer 18. Growing with a film thickness of 300 Å.

(G) Subsequently, a p-type GaN guide layer 22 made of p-type GaN doped with Mg at 1 × 10 ²⁰ / cm ³ and having a band gap smaller than that of the electron block layer 20 is 0.1 μm on the electron block layer 20. Grow with film thickness. The p-type GaN guide layer 22 functions as a light guide layer for the InGaN active layer 18.

(H) Subsequently, on the p-type GaN guide layer 22, a first layer made of p-type Al _0.1 Ga _0.9 N doped with 1 × 10 ²⁰ / cm ^{3 of} Mg, 20 Å, and 1 × 10 ²⁰ Mg. A p-type superlattice clad layer 26 made of a superlattice layer having a total thickness of 0.4 μm is formed by alternately laminating a second layer made of p-type GaN doped with / cm ³ and 20 angstroms. The p-type superlattice clad layer 26 functions as a carrier confinement layer like the n-type superlattice clad layer 14 and acts as a layer for reducing the resistivity on the p-type layer side by adopting a superlattice structure.

(I) Finally, a p-type GaN contact layer 28 made of p-type GaN doped with 2 × 10 ²⁰ / cm ^{3 of} Mg is grown to a thickness of 150 Å.

(J) After the element structure film formation is completed, the wafer is annealed in a nitrogen atmosphere at 700 ° C. to further reduce the resistance of the p-type superlattice cladding layer 26 and the p-type GaN contact layer 28. After annealing, the wafer is taken out and, as shown in FIGS. 1 to 3, the uppermost p-type GaN contact layer 28 and the p-type superlattice clad layer 26 are etched by a dry etching apparatus to obtain a stripe width of 2 μm. A ridge shape is formed.

(K) Next, Ar plasma is irradiated in the insulating film forming apparatus 54 in addition to the upper portion of the ridge to form an extremely thin adhesion layer 23 made of Zr metal. The film thickness is, for example, about 5 nm to 10 nm. At the time of Ar plasma irradiation, since no high frequency is applied to the target 44 in the insulating film forming apparatus 54, no active film formation from the target 44 occurs, and a very small amount of Zr is generated by the extremely low energy Ar plasma. Is sputtered to form a film. For this reason, it is possible to form an extremely thin Zr film.

(L) After this Ar plasma irradiation, an insulating film 24 made of ZrO ₂ is formed on the portion other than the upper portion of the ridge.

(M) Next, a p-side ohmic electrode 30 made of Pd / Au is formed on the ridge surface. The ridge formation position is aligned with the plane orientation of the GaN-based semiconductor substrate 10 so that the m-plane is a cleavage plane (resonance plane).

(N) Next, a p-side electrode 32 electrically connected to the p-side ohmic electrode 30 through the insulating film 24 is formed.

(O) After the p-side electrode 32 is formed, the back surface of the GaN-based semiconductor substrate 10 of the wafer is polished and thinned. Specifically, the thickness is reduced to 100 μm or less, preferably 10 μm thick from the final film thickness by mechanical polishing with a diamond grindstone. Subsequently, the work-affected layer generated in the mechanical polishing operation is removed by a polishing operation using diamond slurry having two types of particle diameters. Subsequently, mirror polishing of the finish is performed using a chemical mechanical polishing (CMP) technique. Through such a process, the film thickness is reduced to a target film thickness of 80 μm.

(P) Next, an n-side electrode 40 made of Al / Ti / Al is formed on the entire back surface of the GaN-based semiconductor substrate 10 on which no element structure is formed.

(Q) Next, the substrate is cleaved at a plane perpendicular to the stripe (a plane corresponding to the resonance plane), that is, the m plane of the GaN-based semiconductor substrate 10, and a resonance plane is formed on the end face of the InGaN active layer 18. In this cleavage process, the shape is changed from the wafer state to the bar state. A dielectric multilayer film made of SiO ₂ and ZrO ₂ is formed on the resonance surface of the element in the bar state, and the bar is cut in a direction parallel to the p-side electrode 32 to obtain a laser chip.

(R) As shown in FIG. 7, the laser chip is installed on the submount 2 by junction-up (the back side of the GaN-based semiconductor substrate 10 is the heat sink 7 side), and the submount 2 is installed on the heat sink 7 of the stem. The p-side electrode 32 is wire-bonded to obtain a finished product. The energization pin 3 and the p-side electrode 32 are connected by a gold (Au) wire 5, and the energization pin 4 and the n-side electrode 40 are connected by an Au wire 6.

When this room-temperature laser oscillation was attempted with this finished product, continuous oscillation at an oscillation wavelength of 405 nm was confirmed at room temperature at a threshold current density of 2.5 kA / cm ² and a threshold voltage of 4.5 V, indicating a lifetime of 500 hours or more. .

  According to the present embodiment, it is possible to provide a nitride semiconductor device and a method for manufacturing the same, which can prevent peeling of the insulating film on the ridge side wall and improve the far field pattern.

[Other embodiments]
As described above, the present invention has been described according to the first embodiment. However, it should be understood that the descriptions and drawings constituting a part of this disclosure are illustrative and limit the present invention. Absent. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  As described above, the present invention includes various embodiments not described herein.

  The nitride semiconductor device of the present invention has a wide range of application fields such as a blue-violet laser diode (LD) for optical disks, a three-wavelength LD, a medical device, a bio-related device, and a full-color laser display.

1 is a schematic bird's-eye view of a nitride semiconductor device according to a first embodiment of the present invention. 1 is a schematic cross-sectional structure diagram of a ridge portion of a nitride semiconductor device according to a first embodiment of the present invention. 3 is an SEM photograph of the ridge portion of the nitride semiconductor device according to the first embodiment of the present invention. The relationship between the beam divergence angle and beam intensity of the horizontal direction of the nitride semiconductor element which concerns on the 1st Embodiment of this invention, and a perpendicular direction. 1 is a schematic cross-sectional structure diagram of an ECR sputtering apparatus applied to a method for manufacturing a nitride semiconductor device according to a first embodiment of the present invention. The Auger depth direction analysis result of the sample which irradiated Ar plasma for 30 minutes in the manufacturing method of the nitride semiconductor device which concerns on the 1st Embodiment of this invention. The figure explaining the mounting mounting state of the nitride semiconductor element which concerns on the 1st Embodiment of this invention. The typical cross-section figure of the ridge part of the nitride semiconductor element which concerns on a prior art example. The SEM photograph of the ridge part of the nitride semiconductor element which concerns on a prior art example. The relationship between the beam divergence angle and beam intensity of the horizontal direction and the vertical direction of the nitride semiconductor device which concerns on a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Nitride semiconductor element 2 ... Submount 3, 4 ... Current-carrying pins 5, 6 ... Gold (Au) wire 7 ... Heat sink 10 ... GaN-type semiconductor substrate 11 ... Regrown layer 12 ... Crack prevention layer 14 ... Super-n-type Lattice cladding layer 16 ... n-type GaN guide layer 18 ... InGaN active layer 20 ... electron blocking layer 22 ... p-type GaN guide layer 23 ... adhesion layer 24 ... insulating film 26 ... p-type superlattice cladding layer 28 ... p-type GaN contact layer 30 ... p-side ohmic electrode 32 ... p-side electrode 40 ... n-side electrode 42 ... sample placement part 44 ... target 46 ... evacuation part 48 ... magnet 50 ... ECR plasma 52 ... microwave plasma introduction part 54 ... insulating film formation Apparatus 80 ... Laser stripe

Claims (13)

A GaN-based semiconductor substrate;
An n-type semiconductor layer disposed on the GaN-based semiconductor substrate;
An active layer containing In disposed on the n-type semiconductor layer;
A p-type semiconductor layer disposed on the active layer;
A compound semiconductor layer disposed on the p-type semiconductor layer and including a ridge shape;
An adhesion layer disposed on a ridge-shaped side wall of the compound semiconductor layer;
And an insulating film disposed on the adhesion layer.   The nitride semiconductor device according to claim 1, wherein the adhesion layer is made of a metal layer or an element semiconductor layer.   The nitride semiconductor element according to claim 1, wherein the adhesion layer is made of any one of Zr, Al, Ti, and Ta.   The nitride semiconductor device according to claim 1, wherein the adhesion layer is made of Si.   The nitride semiconductor device according to claim 1, wherein the adhesion layer has a thickness of 10 nm or less. The insulating film is made of any one of a ZrO ₂ film, a SiO ₂ film, a SiN film, an Al ₂ O ₂ film, an AlN film, a TiO ₂ film, and a Ta ₂ O ₅ film. 2. The nitride semiconductor device according to 1. Forming an n-type semiconductor layer on the GaN-based semiconductor substrate;
Forming an active layer containing In on the n-type semiconductor layer;
Forming a p-type semiconductor layer on the active layer;
Forming a compound semiconductor layer including a ridge shape on the p-type semiconductor layer;
Forming an adhesion layer on a ridge-shaped side wall of the compound semiconductor layer;
And a step of forming an insulating film on the adhesion layer.   The method for manufacturing a nitride semiconductor device according to claim 7, wherein the adhesion layer is made of a metal layer or an element semiconductor layer.   The method for manufacturing a nitride semiconductor device according to claim 7, wherein the adhesion layer is made of any one of Zr, Al, Ti, and Ta.   The method for manufacturing a nitride semiconductor device according to claim 7, wherein the adhesion layer is made of Si.   The method for manufacturing a nitride semiconductor device according to claim 7, wherein the adhesion layer has a thickness of 10 nm or less. The insulating film is made of any one of a ZrO ₂ film, a SiO ₂ film, a SiN film, an Al ₂ O ₂ film, an AlN film, a TiO ₂ film, and a Ta ₂ O ₅ film. The method for producing a nitride semiconductor device according to claim 7.   8. The method for manufacturing a nitride semiconductor device according to claim 7, wherein the step of forming the adhesion layer includes a step of sputtering a metal layer or an element semiconductor layer from a target by Ar plasma irradiation.