JP2009272375A - Method of manufacturing semiconductor laser, and semiconductor laser - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the method of manufacturing a semiconductor laser device, which is excellent in productivity and which can fully assure operation reliability and ESD resistance; and to provide the semiconductor laser device. <P>SOLUTION: In the method of manufacturing a semiconductor laser device 1, a dielectric film 31 is formed which is a first layer in a high reflective film 21 by ECR plasma method; and dielectric films 32 and 33 are formed which are second and subsequent layers by IAD method. Therefore, a damage on an end surface 20a is suppressed and the ESD resistance of the semiconductor laser device 1 can be assured. In second and subsequent films, since internal stress can be offset between the dielectric film 31 which is the first layer and the films, the occurrence of distortion in the laser device P is suppressed and operation reliability can be assured. Further, since the second and subsequent layers are formed by the IAD method having higher productivity than the ECR plasma method, the manufacturing method is excellent in productivity as a whole. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a semiconductor laser manufacturing method and a semiconductor laser.

  Dielectric multilayer films formed by alternately laminating dielectric films having different refractive indexes are used as end face coating films such as an AR coat film and an HR coat film formed on the end face of the semiconductor laser element. For example, an electron cyclotron resonance plasma method (ECR plasma method) or an ion-assisted deposition method (IAD method) is used for manufacturing the dielectric multilayer film.

Further, in the end face coating film of the semiconductor laser element, the layer thickness tends to increase to satisfy a desired reflection characteristic (or transmission characteristic), and the film stress increases accordingly. It is known that when the film stress increases, the element body of the semiconductor laser element is distorted and affects the reliability during operation (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 2002-2223026

  In the ECR plasma method described above, the end face of the semiconductor laser element is not directly exposed to the plasma, and the processing temperature is as low as about 50 ° C., so that damage to the end face can be suppressed, and electrostatic discharge of the semiconductor laser element ( ESD) has an advantage that resistance can be improved.

  On the other hand, in the ECR plasma method, it is difficult to increase the size of the apparatus due to problems such as the weight and price of the plasma source. For this reason, there is a disadvantage that the area where the film can be uniformly formed is limited and sufficient productivity cannot be obtained. In addition, since the direction of the internal stress of the end face coating to be formed cannot be controlled, there is also a drawback that the film stress increases as the film thickness increases.

  Further, the IAD method has an advantage that a dense dielectric can be formed by ion assist. It is also possible to control the direction of internal stress of the end face coating film by adjusting the film forming speed and ion assist conditions. Compared to the ECR plasma method, the size of the apparatus can be increased and it is suitable for mass production. However, the IAD method has a drawback that damage to the end face is likely to occur when the ions hit the end face of the semiconductor laser element.

  Therefore, in the manufacturing method of the semiconductor laser element, there has been a demand for a technique capable of ensuring the operational reliability and the ESD resistance as well as being excellent in productivity by compensating for the disadvantages of both.

  SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a semiconductor laser device manufacturing method and a semiconductor laser device that are excellent in productivity and can sufficiently ensure operation reliability and ESD resistance. And

  In order to solve the above-described problems, a method of manufacturing a semiconductor laser device according to the present invention includes an element body forming step for forming a laser element body including an active layer that generates laser light, and a laser beam in the laser element body. Forming an end face coating film made of a dielectric multilayer film on at least one of the emission end face and the end face facing the emission end face. A first step of forming a first-layer dielectric film by an electron cyclotron resonance plasma method; and a dielectric film of the second and subsequent layers is formed on the surface of the first-layer dielectric film by an ion-assisted deposition method. And a second step of forming.

  In this semiconductor laser device manufacturing method, the first dielectric film in the end face coating film is formed by the electron cyclotron resonance plasma method, and the second and subsequent dielectric films are formed by the ion-assisted deposition method. . By forming the first layer by the electron cyclotron resonance plasma method, damage to the end face of the semiconductor laser element can be suppressed. Further, when the second and subsequent layers are formed, the influence of ion collision is alleviated by the already formed first dielectric layer, so that the damage to the end face of the semiconductor laser device is continuously suppressed. It is done. Thereby, the ESD tolerance of the semiconductor laser element can be sufficiently ensured. On the other hand, the first dielectric film formed by the electron cyclotron resonance plasma method has an internal stress in the compression direction regardless of the film thickness. On the other hand, in the second and subsequent layers, it is possible to give each dielectric film an internal stress in the tensile direction by adjusting the deposition rate and ion assist conditions. Therefore, the internal stress is canceled between the first dielectric film and the second and subsequent dielectric films, and the internal stress in the entire end face coating film is relaxed. As a result, the distortion of the laser element due to the internal stress of the end face coating film can be suppressed, and the operation reliability of the semiconductor laser element can be sufficiently secured. Furthermore, in this semiconductor laser device manufacturing method, the second and subsequent layers are formed by the ion assist method, which is more productive than the electron cyclotron resonance plasma method, so that the overall productivity is excellent.

  Further, it is preferable that the first-layer dielectric film and the second-layer dielectric film are formed of the same material. In this case, since the influence of reflection at the interface between the first dielectric film and the second dielectric film can be mitigated, an end face coating film having desired reflection characteristics (or transmission characteristics) can be easily obtained. be able to.

  Further, it is preferable that a pretreatment step of heating the laser element body at a temperature at which moisture adhering to the first-layer dielectric film can be removed is preferably provided between the first step and the second step. . When the laser element is unloaded from the device used in the electron cyclotron resonance plasma method, moisture in the atmosphere may adhere to the surface of the first dielectric film. When the second and subsequent dielectric layers are formed while the moisture remains on the surface of the first dielectric film, the first dielectric film and the second and subsequent dielectric films Adhesion may be reduced. Therefore, the adhesiveness between the first dielectric film and the second and subsequent dielectric films can be secured by performing the above-described pretreatment process prior to the second process.

  A semiconductor laser device according to the present invention includes a laser element including an active layer that generates laser light, and a dielectric multilayer film. The laser beam emission end face of the laser element, and the emission end face And an end face coating film formed on at least one of the end faces opposite to each other, wherein the first dielectric film facing the end face of the laser element is formed by an electron cyclotron resonance plasma method. The dielectric film is a dielectric film, and the second and subsequent dielectric films are dielectric films formed by ion-assisted deposition.

  In this semiconductor laser element, the first dielectric film in the end face coating film is formed by the electron cyclotron resonance plasma method, and the second and subsequent dielectric films are formed by the ion-assisted deposition method. By forming the first dielectric film by the electron cyclotron resonance plasma method, damage to the end face of the semiconductor laser element can be suppressed. Further, when the second and subsequent layers are formed, the influence of ion collision is alleviated by the already formed first-layer dielectric film, and damage to the end face of the semiconductor laser device is subsequently suppressed. Thereby, the ESD tolerance of the semiconductor laser element can be sufficiently ensured. On the other hand, the first dielectric film formed by the electron cyclotron resonance plasma method has an internal stress in the compression direction regardless of the film thickness. On the other hand, in the film formation after the second layer, it is possible to give each dielectric film an internal stress in the tensile direction by adjusting the film formation speed and ion assist conditions. Therefore, the internal stress is canceled between the first dielectric film and the second and subsequent dielectric films, and the internal stress in the entire end face coating film is relaxed. As a result, the distortion of the laser element due to the internal stress of the end face coating film can be suppressed, and the operation reliability of the semiconductor laser element can be sufficiently secured. Furthermore, in this semiconductor laser device, the second and subsequent layers are formed by the ion assist method, which is more productive than the electron cyclotron resonance plasma method, so that the overall productivity is excellent.

  Further, it is preferable that the first-layer dielectric film and the second-layer dielectric film are formed of the same material. In this case, since the influence of reflection at the interface between the first dielectric film and the second dielectric film can be mitigated, an end face coating film having desired reflection characteristics (or transmission characteristics) can be easily obtained. be able to.

  According to the present invention, it is excellent in productivity, and operation reliability and ESD resistance can be sufficiently secured.

  Hereinafter, preferred embodiments of a semiconductor laser device manufacturing method and a semiconductor laser device according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 describes in detail a preferred embodiment of a semiconductor laser device according to the present invention. FIG. 1 is a sectional view showing an embodiment of a semiconductor laser device according to the present invention. 2 is a cross-sectional view taken along line II-II in FIG.

  The semiconductor laser device 1 shown in FIGS. 1 and 2 is a distributed feedback semiconductor laser. The semiconductor laser device 1 is used as a light source for a long-distance optical communication system that requires a stable single mode. The semiconductor laser element 1 includes a laser element P that generates laser light having a predetermined wavelength.

  The laser element P has a substantially rectangular parallelepiped shape so as to cover the semiconductor substrate 2, the semiconductor mesa portion 3 extending in a predetermined direction on one surface side of the semiconductor substrate 2, and both sides of the semiconductor mesa portion 3. Are formed by the buried layers 4 and 5, the cladding layer 6 formed on the surfaces of the semiconductor mesa portion 3 and the buried layers 4 and 5, and the contact layer 7 formed on the surface of the cladding layer 6. .

  In the laser element P, electrode layers 8 and 9 are formed on the surface of the contact layer 7 and on the other surface side of the semiconductor substrate 2, respectively, in the extending direction (waveguide direction) of the semiconductor mesa portion 3. A high reflection film 21 and an antireflection film 22 are formed on the end faces 20a and 20b, respectively.

  The semiconductor substrate 2 is, for example, an n-type InP substrate doped with Sn. The thickness of the semiconductor substrate 2 is about 100 μm. The semiconductor mesa unit 3 is configured by laminating a cladding layer 11, an active layer 12, a diffraction grating forming layer 13, and a cladding layer 14 in order from the semiconductor substrate 2 side. The semiconductor mesa unit 3 is formed in a stripe shape by cutting a semiconductor region including the active layer 12 in the stacking direction by etching.

  The active layer 12 is, for example, an InGaAsP layer. The active layer 12 has, for example, a multiple quantum well (MQW) structure. Carriers are injected into the active layer 12 from the cladding layer 11 and the cladding layers 6 and 14, and light is generated by recombination of the carriers.

  The clad layer 11 of the semiconductor mesa unit 3 is, for example, an n-type InP layer doped with Si. The clad layer 14 is a p-type InP layer doped with, for example, Zn. The refractive index of the cladding layers 11 and 14 is smaller than that of the active layer 12, whereby the cladding layers 11 and 14 function as a layer that confines light generated in the active layer 12.

  The diffraction grating forming layer 13 is, for example, an InGaAsP layer doped with Zn. As shown in FIG. 2, the diffraction grating forming layer 13 is formed with a diffraction grating G composed of a periodic concavo-convex pattern along the waveguide direction. The depth of each recess in the concavo-convex pattern is 30 nm, for example, and the interval is 120 nm, for example.

  Such a diffraction grating forming layer 13 reflects a part of the light traveling inside the active layer 12 along the longitudinal direction of the semiconductor mesa portion 3 in a direction opposite to the traveling direction. As a result, light having a wavelength determined by the period of the concavo-convex pattern in the diffraction grating G is fed back inside the active layer 12.

  The buried layer 4 is, for example, a p-type InP layer doped with Zn. The buried layer 4 increases in thickness as it approaches the side of the semiconductor mesa unit 3 and covers up to the side of the cladding layer 14. On the other hand, the buried layer 5 is, for example, a p-type InGaAs layer doped with Fe. The buried layer 5 is formed so as to cover the surface of the buried layer 4, and the surface of the buried layer 5 is in a flat state.

  The clad layer 6 is, for example, a p-type InP layer doped with Zn. The clad layer 6 is formed so as to cover the clad layer 14 and the buried layers 4 and 5 of the semiconductor mesa unit 3, and enhances the light confinement effect inside the active layer 12 in cooperation with the clad layer 14. ing.

  The contact layer 7 is, for example, a p-type InGaAs layer doped with Zn. The contact layer 7 realizes ohmic contact between the electrode layer 8 and the cladding layer 6. The electrode layer 8 and the electrode layer 9 are, for example, Au plating layers and have a thickness of about 10 μm. The electrode layer 8 is formed on the surface of the contact layer 7, and the electrode layer 9 is formed on the other surface of the semiconductor substrate 2.

  The high reflection film 21 and the antireflection film 22 are dielectric multilayer films formed by alternately laminating dielectric films having different refractive indexes. The high reflection film 21 has a reflectance of, for example, 80% or more with respect to the oscillation wavelength, and has a function of enhancing the reflection at the end face 20a of the laser element P. The antireflection film 22 has a reflectivity with respect to the oscillation wavelength of, for example, 5% or less, and has a function of reducing reflection at the end face 20b of the laser element P.

  As shown in FIG. 3, the highly reflective film 21 includes a first dielectric film 31 formed by an electron cyclotron resonance plasma method (hereinafter referred to as “ECR plasma method”) and an ion-assisted deposition method (hereinafter referred to as “ECR plasma deposition method”). The second to seventh dielectric films 32 and 33 are alternately formed by “IAD method”.

The dielectric film 31 is made of, for example, Al ₂ O ₃ . The film thickness of the dielectric film 31 is, for example, 200 to 500 mm. The dielectric film 31 has a function of alleviating damage to the end face 20a when the second and subsequent dielectric films 32 and 33 are formed by the IAD method.

  The index of damage to the end face 20a is represented by, for example, electrostatic discharge resistance (hereinafter referred to as “ESD resistance”) of the semiconductor laser element 1. In the IAD method, an inert gas such as Ar gas is used in a plasma form in order to obtain a dense film that hardly deteriorates with time. When this plasma hits the end face 20a of the laser element P, a digling bond is formed on the end face 20a, and the ESD resistance may be reduced. The lower limit of the film thickness of the dielectric film 31 described above is the minimum film thickness in a range necessary for the semiconductor laser device 1 to maintain an ESD resistance of 1 kV or more in both the forward direction and the reverse direction.

  The high reflection film 21 is optimally designed only by the second and subsequent dielectric films 32 and 33 formed by the IAD method. When the film thickness of the dielectric film 31 increases, the high reflection film 21 is increased. The reflectance of the liquid crystal gradually decreases. Therefore, the upper limit of the film thickness of the dielectric film 31 is the maximum film thickness in a range necessary for maintaining the reflectance with respect to the oscillation wavelength at 80% or more.

  Further, the dielectric film 31 formed by the ECR plasma method has an internal stress in the compression direction regardless of the film thickness. In the film configuration described above, the internal stress of the dielectric film 31 is, for example, about 300 MPa to 350 MPa in the compression direction.

The dielectric film 32 is made of, for example, Al ₂ O ₃ . The film thickness of the dielectric film 32 is, for example, 2015 mm. The dielectric film 33 is made of, for example, TiO ₂ . The film thickness of the dielectric film 33 is, for example, 1430 mm. The first dielectric film 31 and the second dielectric film 32 are both made of Al ₂ O ₃ and are actually integrated.

  The dielectric films 32 and 33 have a function of canceling out the internal stress of the dielectric film 31. In the above-described film configuration, the internal stresses of the second to seventh dielectric films 32 and 33 are, for example, about 210 MPa in the tensile direction by adjusting the film formation rate and ion assist conditions. The internal stress of the first dielectric film 31 is offset by the internal stress of the second to seventh dielectric films 32 and 33. The internal stress in the entire high reflection film 21 depends on the second to seventh dielectric films 32 and 33 having a larger film thickness, and is, for example, 180 MPa to 200 MPa in the tensile direction.

  As shown in FIG. 4, the antireflection film 22 includes a first-layer dielectric film 41 formed by an ECR plasma method and second- to third-layer dielectric layers alternately formed by an IAD method. The body membranes 42 and 43 are configured.

The dielectric film 41 is made of, for example, Al ₂ O ₃ , similarly to the dielectric film 31 of the highly reflective film 21. The film thickness of the dielectric film 41 is, for example, 200 to 500 mm, and alleviates damage to the end face 20b when the second and third dielectric films 42 and 43 are formed by the IAD method. It has a function.

The second dielectric film 42 is made of, for example, Al ₂ O ₃ . The film thickness of the dielectric film 42 is, for example, 1080 mm. The third dielectric film 43 is made of, for example, TiO ₂ . The film thickness of the dielectric film 43 is, for example, 450 mm. The first dielectric film 41 and the second dielectric film 42 are both made of Al ₂ O ₃ and are actually integrated.

  Then, the manufacturing method of the semiconductor laser element 1 mentioned above is demonstrated.

  In manufacturing the semiconductor laser element 1, a semiconductor substrate 2 is prepared. Next, the clad layer 11, the active layer 12, and the diffraction grating formation layer 13 are grown on one surface of the semiconductor substrate 2 by, for example, metal organic vapor phase epitaxy.

  Next, a resist is applied to the surface of the diffraction grating formation layer 13, and lines and spaces having a predetermined pitch are formed in the resist using, for example, an electron beam exposure apparatus. Then, the surface of the diffraction grating forming layer 13 is wet etched to form the diffraction grating G. Thereafter, the cladding layer 14 is grown on the surface of the diffraction grating forming layer 13.

  Next, a stripe-shaped insulating layer is formed on the surface of the cladding layer 15 by using, for example, photolithography. Then, using this insulating layer as a mask, the cladding layer 14, the diffraction grating formation layer 13, and the active layer 12 are etched by dry etching, for example. Thereby, the semiconductor mesa portion 3 is formed.

  After the formation of the semiconductor mesa unit 3, the buried layers 4 and 5 are grown so as to embed the semiconductor mesa unit 3 by, for example, metal organic vapor phase epitaxy. Thereafter, the cladding layer 6 and the contact layer 7 are formed on the surfaces of the cladding layer 14 and the buried layer 5 by, for example, metal organic vapor phase epitaxy. Next, the electrode layers 8 and 9 are formed on the surface of the contact layer 7 and the other surface side of the semiconductor substrate 2 to form the laser element P.

  After the laser element P is formed, an end face coating film is formed. In the film forming step, first, the laser element P is introduced into the ECR plasma apparatus, and the first dielectric film 31 in the high reflection film 21 is formed on the end surface 20a of the laser element P (first film). Process). The film forming temperature by the ECR plasma apparatus is 50 ° C., for example. After the formation of the dielectric film 31, the laser element P is introduced into the IAD device, and subsequently to the formation of the first dielectric film 31, the second to seventh dielectric films 32, 33 is formed (second step). The film forming temperature by the IAD apparatus is 250 ° C., for example. A known apparatus can be used for both the ECR plasma apparatus and the IAD apparatus.

  By the way, after the film formation by the ECR plasma apparatus, when the film formation by the IAD apparatus is performed, the laser element body P is once carried out into the atmosphere. At this time, moisture in the atmosphere may adhere to the surface of the dielectric film 31 formed on the end face 20a. If the second and subsequent dielectric layers 32 and 33 are formed while the moisture remains on the surface of the dielectric film 31, the adhesion between the dielectric film 31 and the dielectric films 32 and 33 may be reduced. .

  Therefore, in the present embodiment, prior to the film formation process by the IAD apparatus, a pretreatment process is performed in which the laser element P is heated at a temperature at which moisture adhering to the first dielectric film 31 can be removed. FIG. 5 is a diagram showing the temperature of the laser element P in all film forming steps including the pretreatment step. As shown in the figure, in the film forming process in the ECR apparatus, the temperature of the laser element P is maintained at about 50 ° C. for about 15 minutes.

  The laser element P is maintained at a room temperature (about 25 ° C.) level after being unloaded from the ECR apparatus and being introduced into the IAD apparatus. After being introduced into the IAD apparatus, a pretreatment step of approximately 30 minutes is performed in the pretreatment step. In the pretreatment process, the temperature of the laser element P rapidly increases from room temperature to about 250 ° C. After the pretreatment process, in the film forming process in the IAD apparatus, the temperature of the laser element P is maintained at about 250 ° C. for about 45 minutes.

  After the formation of the high reflection film 21, the antireflection film 22 is formed on the end face 20b of the laser element P by the same method, whereby the semiconductor laser device 1 shown in FIGS. 1 and 2 is completed.

  As described above, in the method of manufacturing the semiconductor laser device 1 according to this embodiment, the first dielectric film 31 in the highly reflective film 21 is formed by the ECR plasma method, and the second and subsequent dielectrics are formed. The films 32 and 33 are formed by the IAD method. The same method is used for the antireflection film 22.

  In the ECR plasma method, the end faces 20a and 20b are not directly exposed to the plasma, and the processing temperature is as low as about 50 ° C., so the first layer is formed on the end faces 20a and 20b of the semiconductor laser device 1. Damage can be reduced. In addition, when the second layer and subsequent layers are formed, the influence of ion collision is mitigated by the already formed first layer, so that damage to the end faces 20a and 20b of the semiconductor laser element can be suppressed. . Thereby, the ESD tolerance of the semiconductor laser element can be sufficiently ensured.

  On the other hand, the first dielectric films 31 and 41 formed by the ECR plasma method have internal stress in the compression direction regardless of the film thickness. On the other hand, in the second and subsequent layers, the dielectric films 32, 33, 42, and 43 can be given internal stress in the tensile direction by adjusting the film formation rate and ion assist conditions. ing. Therefore, the internal stress is canceled between the first dielectric films 31 and 41 and the second and subsequent dielectric films 32, 33, 42, and 43, and the high reflection film 21 and the antireflection film 22 as a whole. The internal stress at is relaxed.

  Thereby, generation | occurrence | production of the distortion of the laser element P by the internal stress of the high reflection film 21 and the antireflection film 22 is suppressed, and the operation reliability of the semiconductor laser element 1 can be sufficiently secured. Further, in this semiconductor laser device manufacturing method, the second and subsequent layers are formed by the IAD method, which is more productive than the ECR plasma method, so that the overall productivity is excellent.

  In the method for manufacturing the semiconductor laser device 1 according to this embodiment, the first dielectric films 31 and 41 and the second dielectric films 32 and 42 are formed of the same material. As a result, the influence of reflection at the interface between the first-layer dielectric films 31 and 41 and the second-layer dielectric films 32 and 42 can be alleviated, so that a high reflection characteristic (or transmission characteristic) can be obtained. The reflection film 21 and the antireflection film 22 can be easily obtained.

  Further, in the method for manufacturing the semiconductor laser device 1 according to the present embodiment, the laser element P at a temperature at which moisture adhering to the first dielectric films 31 and 41 can be removed prior to film formation by the IAD method. A pretreatment step of heating the substrate. By this pretreatment process, moisture in the atmosphere attached to the surfaces of the first dielectric films 31 and 41 when the laser element is unloaded from the ECR plasma apparatus is removed, and the first dielectric film is removed. Adhesion between the first and second dielectric films 32, 33, 42, and 43 can be ensured. Whether or not the film adheres can be determined by observing the presence or absence of film peeling in an environment in which a load such as a heat cycle is applied.

  Subsequently, test results of an effect confirmation test of the semiconductor laser device manufacturing method according to the present invention will be described.

  In this effect confirmation test, samples (samples 1 to 4) of semiconductor laser elements on which end face coating films having different configurations were formed were prepared, and the internal stress, ESD resistance, and operation reliability of the end face coating films in each sample were measured. It is a thing.

In sample 1 (comparative example), the first dielectric film by the ECR method is not formed, and the same films as the second to seventh dielectric films 32 and 33 are formed by the IAD method. It is formed directly on the end face of the laser element. In sample 2 (example), a first dielectric film made of Al ₂ O ₃ is formed with a thickness of 200 mm by ECR, and second to seventh layers similar to sample 1 are formed by IAD. A dielectric film as a layer is formed on the end face of the laser element.

In sample 3 (example), a first dielectric film made of Al ₂ O ₃ is formed to a thickness of 500 mm by ECR, and second to seventh layers similar to sample 1 are formed by IAD. A dielectric film as a layer is formed on the end face of the laser element. Sample 4 (Comparative Example) is obtained by directly forming the second to seventh dielectric films on the end face of the laser element by the ECR method.

  FIG. 6 is a diagram showing the test results. As shown in the figure, in Sample 1, the internal stress in the entire end face coating film was 211 MPa in the tensile direction. Sample 1 had no problem in operation reliability, but the ESD tolerance was less than 1 kV in both the forward and reverse directions. In Sample 2, the internal stress of the first dielectric film was 337 MPa in the compression direction, and the internal stress of the second to seventh dielectric films was 211 MPa in the tensile direction. The internal stress in the entire end face coating film was 206 MPa in the tensile direction. Sample 2 gave good results for both ESD tolerance and operational reliability.

  In Sample 3, the internal stress of the first dielectric film is 312 MPa in the compression direction, and the internal stress of the second to seventh dielectric films is 211 MPa in the tensile direction. It was. The internal stress in the entire end face coating film was 188 MPa in the tensile direction. Sample 3 had good results in terms of both ESD resistance and operational reliability, similar to Sample 2. In sample 4, the internal stress in the entire end face coating film was 776 MPa in the compression direction. Sample 4 had no problem in ESD resistance, but good operation reliability was not obtained.

  From the above results, forming the first dielectric film by the ECR plasma method and forming the second and subsequent dielectric films by the IAD method alleviates the internal stress of the end face coating film and the laser element. It was confirmed that the damage to the end face of the body was reduced and it contributed to ensuring the ESD resistance and operation reliability of the semiconductor laser element.

It is a figure which shows one Embodiment of the semiconductor laser element which concerns on this invention. It is the II-II sectional view taken on the line in FIG. It is the figure which showed the layer structure of the high reflection film. It is the figure which showed the layer structure of the antireflection film. It is the figure which showed the temperature of the laser element body in the film-forming process. It is a figure which shows the test result of the effect confirmation test of the manufacturing method of the semiconductor laser element concerning this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Semiconductor laser element, 12 ... Active layer, 20a, 20b ... End face, 21 ... High reflection film, 22 ... Antireflection film, 31, 41 ... Dielectric film (1st layer dielectric film), 32, 33 , 42, 43... Dielectric film (dielectric film after the second layer), P... Laser element.

Claims (5)

An element body forming step of forming a laser element body including an active layer for generating laser light;
A film forming step of forming an end face coating film made of a dielectric multilayer film on at least one of the laser light emitting end face and the end face facing the emitting end face in the laser element body,
The film forming step includes
A first step of forming the first dielectric film on the end face of the laser element by electron cyclotron resonance plasma;
And a second step of forming a second and subsequent dielectric films on the surface of the first dielectric film by ion-assisted deposition. .   2. The method of manufacturing a semiconductor laser according to claim 1, wherein the first dielectric film and the second dielectric film are formed of the same material.   A pretreatment step of heating the laser element body at a temperature capable of removing moisture adhering to the first-layer dielectric film is further provided between the first step and the second step. The method of manufacturing a semiconductor laser according to claim 1 or 2. A laser element body including an active layer for generating laser light;
It is composed of a dielectric multilayer film, and includes an end face coating film formed on at least one of an end face facing the exit end face of the laser beam in the laser element body, and
In the end face coating film,
The first dielectric film facing the end face of the laser element is a dielectric film formed by an electron cyclotron resonance plasma method,
2. The semiconductor laser device according to claim 1, wherein the second and subsequent dielectric films are dielectric films formed by ion-assisted deposition.   5. The semiconductor laser device according to claim 4, wherein the first-layer dielectric film and the second-layer dielectric film are formed of the same material.

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