JP2014011226A - Semiconductor laser device manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor laser device which can efficiently stabilize an end face coating film provided on a resonator end face while inhibiting damages to a laser element.SOLUTION: A semiconductor laser device manufacturing method comprises: an end face formation process of forming resonator end faces 128 having a first end face 128a used as a laser beam emitting side and a second end face 128b opposite to the first end face 128a; a film formation process of forming a first end face coating film 14 on the first end face 128a and a second end face coating film 15 on the second end face 128b; and a light irradiation process of irradiating at least the second end face coating film 15 among the first end face coating film 14 and the second end face coating film 15 with light.

Description

  The present invention relates to a method for manufacturing a semiconductor laser device.

  In a semiconductor laser device, for the purpose of stabilizing the resonator end surface, an end surface coat that coats and protects the resonator end surface is generally provided on the resonator end surface. This end face coating film is typically composed of a single-layer or multilayer dielectric film (see, for example, Patent Document 1). Usually, in order to reduce the threshold value and increase the efficiency (Eta), an end face coating film having a low reflectance with respect to the laser oscillation wavelength light is formed on the front surface from which the laser light is emitted. On the other hand, an end face coating film having a high reflectance is formed on the rear surface (the surface facing the front surface).

  By the way, if a defect exists in the end face coat film, the semiconductor laser device may cause light loss due to deterioration of the end face coat film when laser light is emitted. In consideration of such points, Patent Document 2 discloses that melt recrystallization is applied to the end face coat film (at least the end face coat film formed on the resonator end face on the light emission side of the semiconductor laser). Irradiating a laser beam (excimer laser) to be generated is disclosed.

JP 2002-335053 A JP 2006-190797 A

  However, as disclosed in Patent Document 2, using a technique in which the end face coat film is melted and recrystallized by irradiating a short wavelength laser beam absorbed by the end face coat film, a laser element constituting the semiconductor laser device There is concern that the temperature will be quite high. When the element becomes extremely high in temperature, there is a concern that the element itself is damaged and the characteristics and reliability of the element are deteriorated.

  The laser element constituting the semiconductor laser device can be stabilized by performing a burn-in process without performing laser annealing as disclosed in Patent Document 2. Here, the burn-in process is a process of stabilizing the laser element by driving the apparatus for a certain time after the assembly of the semiconductor laser apparatus. If a defective device is found in this burn-in process, the device is removed as a defective product.

  The burn-in process includes, for example, an APC (Auto Power Control) burn-in that is driven to have a constant optical output (optical power) and an ACC (Auto Current Control) burn-in that is driven to have a constant driving current. . By the burn-in process, the dopant moves or changes the strain of the laser element. In the burn-in process, the laser beam passes through the end face coat film, the crystals constituting the end face coat film are excited, and molecular vibration and lattice vibration are generated. As a result, for example, the refractive index, transmittance, and reflectance of the end face coating film change.

  The light output in the burn-in process is usually about the maximum rated output of the semiconductor laser device. That is, the light output in the burn-in process is not so large, and it takes a long time to stabilize the inside of the laser element and the end face coating film. In order to shorten the time required for stabilization, it is conceivable to increase the light output in the burn-in process. However, if the light output is excessively increased, there is a problem that the possibility that the laser element is deteriorated increases.

  In particular, as described above, the reflectance of the end face coat film is set high on the rear face side of the resonator end face, and the laser light passing through the end face coat film is reduced. For this reason, it takes a long time to stabilize the end face coat film on the rear face side of the resonator end face as compared with the end face coat film on the front face side of the resonator end face. For example, some semiconductor laser devices monitor the optical power of light emitted from the rear side of the resonator end face. In such a semiconductor laser device, it is necessary to sufficiently stabilize the end face coat film provided on the rear face side of the resonator end face. That is, when an attempt is made to manufacture a semiconductor laser device that requires stabilization of the end face coat film provided on the rear face side of the resonator end face, there is a problem that the time required for the burn-in process becomes long and the production efficiency tends to deteriorate.

  In view of the above, the present invention is to provide a method for manufacturing a semiconductor laser device, which can efficiently stabilize an end face coating film provided on a resonator end face while suppressing damage to a laser element.

  In order to achieve the above object, a method of manufacturing a semiconductor laser device according to the present invention includes a first end surface used as a laser beam emitting side and a second end surface facing the first end surface. An end face forming step of forming a vessel end face; a film forming step of forming a first end face coat film on the first end face; and forming a second end face coat film on the second end face; Of the end face coat film and the second end face coat film, at least a light irradiating step for irradiating light to the second end face coat film (first structure).

  According to this configuration, the end face coat film can be stabilized by exciting the crystals constituting the end face coat film and generating molecular vibration and lattice vibration by the light irradiation step. The light irradiation process irradiates light using an external light source, and the light output can be set higher than burn-in that uses the laser elements that make up the semiconductor laser device to stabilize the end coat film, etc. It is. As a result, according to this configuration, it is possible to efficiently stabilize the end face coating film while suppressing damage to the laser element. Note that the second end face coat film has a tendency to increase the time required for stabilization because the reflectance with respect to the light emitted from the laser element constituting the semiconductor laser device is set high. The time required for stabilization of the second end face coating film can be shortened by the introduction.

  The method of manufacturing the semiconductor laser device having the first configuration further includes a burn-in step of driving the laser element constituting the device to emit light for a predetermined time after the light irradiation step (second configuration) ). Since the second end face coat film is set to have a high reflectance with respect to light emitted from the laser element constituting the semiconductor laser device, the burn-in process alone tends to increase the time required for stabilization. In this regard, in this configuration, since the light irradiation process is introduced, the burn-in process can be shortened.

  In the method for manufacturing a semiconductor laser device having the first or second configuration, the wavelength of light used in the light irradiation step is within ± 10 nm with respect to the oscillation wavelength of the semiconductor laser device (third Configuration) is preferable. Thereby, the effect of stabilizing the end face coating film can be further increased.

  In the method of manufacturing a semiconductor laser device having any one of the first to third configurations, the light used in the light irradiation step has a light transmittance of 5% or more with respect to the second end surface coating film. (4th structure) is preferable. This configuration is suitable for a semiconductor laser device incorporating a rear monitor, for example.

  In the method for manufacturing a semiconductor laser device having any one of the first to fourth configurations, the semiconductor laser device includes a monitor element for monitoring the optical power of the laser light emitted from the device (first configuration). 5 configuration). In the semiconductor laser device in which the monitor element (rear monitor) is built in, the process for stabilizing the second end face coating film is important, and the significance of introducing the light irradiation step is great.

  In the method of manufacturing a semiconductor laser device having any one of the first to fifth configurations, the semiconductor laser device preferably has a configuration (sixth configuration) formed using a nitride III-V group compound semiconductor. . Nitride-based III-V group compound semiconductors are suitable as a material constituting a semiconductor laser device because of their wide use and low environmental impact.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the semiconductor laser apparatus which can stabilize efficiently the end surface coating film provided in a resonator end surface can be provided, suppressing the damage with respect to a laser element.

1 is a schematic perspective view showing a configuration example of a semiconductor laser device according to an embodiment of the present invention. Schematic showing a configuration example of a semiconductor laser device according to an embodiment of the present invention 1 is a schematic plan view showing an example of a laminated structure of semiconductor laser chips provided in a semiconductor laser device according to an embodiment of the present invention. Schematic diagram showing a configuration example of an end face coating film provided on a semiconductor laser chip provided in a semiconductor laser device according to an embodiment of the present invention The schematic diagram for demonstrating the light irradiation process included in the manufacturing method of the semiconductor laser apparatus concerning embodiment of this invention Schematic plan view showing the detailed configuration of the LD bar assembly shown in FIG. The graph which shows the time change of the drive current (Iop) in the semiconductor laser apparatus of a present Example. The graph which shows the time change of the rate of change of the monitor output current (Imop) and the monitor output current (Imop) in the semiconductor laser device of this example. The graph which shows the time change of the drive current (Iop) in the semiconductor laser apparatus of a comparative example The graph which shows the time change of the rate of change of the monitor output current (Imop) and the monitor output current (Imop) in the semiconductor laser device of the comparative example.

  Hereinafter, a method for manufacturing a semiconductor laser device according to an embodiment of the present invention will be described with reference to the drawings.

<Schematic configuration of semiconductor laser device>
First, a schematic configuration of a semiconductor laser device according to an embodiment of the present invention will be described. FIG. 1 is a schematic perspective view showing a configuration example of a semiconductor laser device 1 according to an embodiment of the present invention. FIG. 2 is a schematic diagram illustrating a configuration example of the semiconductor laser device 1 according to the embodiment of the present invention. FIG. 2A is a plan view illustrating a state where the cap 30 is removed, and FIG. It is sectional drawing in the AA position of Fig.2 (a).

  The semiconductor laser device 1 according to the present embodiment is a can package type semiconductor laser device as shown in FIGS. As shown in FIG. 1, the semiconductor laser device 1 includes a stem 10, three lead pins 20, 21 and 22, and a cap 30.

  The stem 10 is formed in a disk shape and is made of a metal material such as iron or copper. As shown in FIG. 2, a block portion 10 a having a radiation function is formed on the upper surface side of the stem 10. On the block part 10a, the heat sink 11 is fixed by, for example, an adhesive (not shown). The heat sink 11 is formed of a material having good heat radiation, such as AlN. On the heat sink 11, a semiconductor laser chip 12 (an example of the laser element of the present invention) that emits laser light is mounted via a solder layer (not shown). The semiconductor laser chip 12 has a stacked structure in which a plurality of nitride compound semiconductor layers are stacked. The detailed configuration of the semiconductor laser chip 12 will be described later. A monitor element (photodiode) 13 for detecting light from the semiconductor laser chip 12 is fixed to the upper surface of the stem 10 using an adhesive (not shown) or the like. This monitor element 13 is a so-called rear monitor.

  The lead pin 20 is directly attached to the stem 10. Each of the lead pin 21 and the lead pin 22 is inserted into a through hole (not shown) formed in the stem 10, so that one end portion projects to the upper surface side of the stem 10 and the other end portion faces to the lower surface side of the stem 10. It is attached to the stem 10 in a protruding state (see FIG. 2). The lead pins 21 and 22 are insulated and fixed to the stem 10 via an insulator (not shown). In addition, the semiconductor laser chip 12 and the monitor element 13 are appropriately electrically connected to these lead pins 20 to 22 through wires or the like (not shown).

  The cap 30 is formed in a cylindrical shape having an open lower end surface, and is made of a metal such as copper. A flange portion 30 a is provided at the open end of the cap 30. The cap 30 is fixed to the upper surface of the stem 10 so as to cover the semiconductor laser chip 12 and the like on the stem 10 by fixing the flange portion 30 a to the stem 10. The semiconductor laser chip 12 is hermetically sealed by the cap 30. Further, at the upper end of the cap 30, an emission hole 30b for taking out the laser light emitted from the semiconductor laser chip 12 is formed. The exit hole 30 b is covered with a glass window 31.

  In the semiconductor laser device 1 configured as described above, the semiconductor laser chip 12 is formed using a nitride III-V compound semiconductor. Here, the nitride-based III-V compound semiconductor includes at least one group III element selected from the group consisting of Ga, Al, In, and B, and at least N. And a compound semiconductor composed of a group V element containing. Examples of the nitride III-V group compound semiconductor include AlGaInN, GaInN, InN, and the like.

  Further, in the semiconductor laser device 1 configured as described above, the resonator end faces are provided on the front side (upper surface side in FIG. 2) and rear side (lower surface side in FIG. 2) of the semiconductor laser chip 12 in the light emission direction. Is formed. The resonator end face is an end face obtained by cleaving or the like in order to realize a function as a resonator.

An end face coat film is formed on the end face of the resonator for the purpose of preventing oxidation of crystals near the end face. The end face coating film is formed of a single-layer or multilayer dielectric film. Examples of the dielectric film include those composed of a material containing at least one element selected from the group consisting of Al, Ti, Zr, Hf, Ta, Zn, and Si, and more specifically, Examples thereof include those composed of Al ₂ O ₃ , AlN, and AlON.

  Hereinafter, the configuration of the semiconductor laser chip 12 will be described in more detail by taking as an example the case where the semiconductor laser chip 12 is configured using an AlGaInN-based compound semiconductor. FIG. 3 is a schematic plan view showing an example of a laminated structure of the semiconductor laser chip 12 included in the semiconductor laser device 1 according to the embodiment of the present invention. As shown in FIG. 3, the semiconductor laser chip 12 has a structure in which a plurality of compound semiconductor layers are stacked. The configuration illustrated in FIG. 3 is merely an example, and the material, thickness, and the like may be changed as appropriate.

  As shown in FIG. 3, the semiconductor laser chip 12 includes a substrate 120 on the surface of which an n-type nitride semiconductor layer 121, an active layer 122, and a p-type nitride semiconductor layer 123 are provided. The substrate 120 can be an n-type GaN substrate having a thickness of about 40 to 150 μm, for example. The substrate material is not limited to GaN, and may be, for example, InN, AlN, or a mixed crystal semiconductor obtained by selecting two or more of GaN, InN, and AlN. Absent. The substrate material may be, for example, sapphire, spinel, SiC, Si, or a III-V group compound (eg, GaAs, GaP, etc.) other than nitride.

  The n-type nitride semiconductor layer 121 provided on the substrate 120 may include a lower contact layer 121a, a lower cladding layer 121b, and a lower guide layer 121c. The lower contact layer 121a formed on the substrate 120 can be made of n-type GaN having a thickness of about 0.1 μm to 10 μm (about 1 μm in this example), for example. The lower clad layer 121b provided on the lower contact layer 121a can be made of n-type AlGaN having a thickness of, for example, about 0.5 μm to 3 μm (about 2 μm in this example). The lower guide layer 121c provided on the lower cladding layer 121b can be made of n-type GaN having a thickness of about 0 to 0.2 μm (in this example, about 0.1 μm), for example.

  A buffer layer may be provided between the substrate 120 and the lower contact layer 121a. Further, a crack prevention layer made of, for example, an InGaN layer or the like may be inserted between the lower contact layer 121a and the lower cladding layer 121b. Further, the lower clad layer 121b may have a multilayer structure, and may have a multiple quantum well structure.

  The active layer 122 is formed on the lower guide layer 121c. The active layer 122 can have, for example, a multiple quantum well structure (in this example, a thickness of about 0.053 μm) made of InGaN. Note that the active layer 122 may be configured using, for example, GaInNAs or GaInP.

  The p-type nitride semiconductor layer 123 provided on the active layer 122 may include an evaporation prevention layer 123a, an upper guide layer 123b, an upper cladding layer 123c, and an upper contact layer 123d. The evaporation prevention layer 123a formed on the active layer 122 can be composed of p-type AlGaN having a thickness of, for example, about 0 to 0.02 μm (in this example, about 0.02 μm). The upper guide layer 123b formed on the evaporation prevention layer 123a can be composed of, for example, p-type GaN of about 0 to 0.2 μm (in this example, about 0.1 μm). The upper cladding layer 123c (thickness of about 0.5 μm in this example) formed on the upper guide layer 123b is configured to have a convex portion and a flat portion other than the convex portion, and can be composed of p-type AlGaN. The upper contact layer 123d formed on the convex portion of the upper cladding layer 123c can be made of p-type GaN having a thickness of, for example, about 0.01 μm to 1.0 μm (in this example, about 0.1 μm).

  The upper clad layer 123c may be made of, for example, AlGaInN. Further, the upper clad layer 123c may have a multilayer structure, and may have a multiple quantum well structure.

  The convex portion of the upper cladding layer 123c and the upper contact layer 123d form a striped (elongated) ridge portion 124 extending in a direction orthogonal to the resonator end surface (a direction orthogonal to the paper surface in FIG. 3 corresponds). ing. That is, the semiconductor laser chip 12 has a ridge stripe structure.

  The ridge portion 124 is not formed only by the upper clad layer 123c and the upper contact layer 123d, but is formed by digging up to somewhere in the range from the upper guide layer 123b to the active layer 122. It doesn't matter.

A buried layer 125 is formed on both sides of the ridge portion 124 for the purpose of current confinement. The buried layer 125 can be formed of an insulating material such as SiO ₂ , SiN, Al ₂ O ₃ , or ZrO ₂ (in this example, SiO ₂ is used).

  A p-side electrode 126 for injecting carriers from the upper surface of the ridge portion 124 is formed on the upper contact layer 123 d and the buried layer 125. The p-side electrode 126 is formed so as to cover a part of the upper contact layer 123d, and is in ohmic contact with the upper contact layer 123d. As the p-side electrode 126, for example, a metal such as Ni, Pd, Pt, or Au, or a laminate including these metals can be used. In this example, the p-side electrode 126 is a laminated body arranged in the order of Pd (about 15 nm) / Mo (about 15 nm) / Au (about 200 nm) from the side close to the upper contact layer 123d.

  On the back surface of the substrate 120, an n-side electrode 127 for injecting carriers from below the substrate is formed. The n-side electrode 127 is in ohmic contact with the substrate 120. As the n-side electrode 127, for example, a metal such as Hf, Ti, Al, or W, or a laminate including these metals can be used. In this example, the n-side electrode 127 is arranged in the order of Ti (about 30 nm) / Al (about 150 nm) / Mo (about 8 nm) / Pt (about 15 nm) / Au (about 250 nm) from the side close to the substrate 120. It is a laminate.

  FIG. 4 is a schematic diagram showing a configuration example of the end surface coating films 14 and 15 provided on the semiconductor laser chip 12 included in the semiconductor laser device 1 according to the embodiment of the present invention. As shown in FIG. 4, the semiconductor laser chip 12 has a resonator end face 128 having a front end face 128a and a rear end face 128b. The front side end face 128a is an end face on the front side (outgoing side; right side in FIG. 4) in the light emitting direction, and is an example of the first end face of the present invention. The rear end face 128b is an end face on the opposite side (the side facing the front end face 128a; the left side in FIG. 4) with respect to the front end face 128a, and is an example of the second end face of the present invention. is there.

On the front side end face 128a, a first end face coat film 14 (hereinafter referred to as “AR coat film 14”) in which the laser oscillation wavelength light (in this example, light of 405 nm) exhibits low reflectivity is formed. . The AR coating film 14 is not intended to limit the film configuration and film thickness, but can be a multilayer dielectric film (thickness of about 1500 mm) made of, for example, AlON / SiN / Al ₂ O ₃ . The AR coating film 14 is appropriately changed depending on whether the semiconductor laser device 1 is, for example, a high output type or a low output type, and the reflectance thereof is adjusted to, for example, about several% to 50%. Is done.

On the rear side end face 128b, a second end face coat film 15 (hereinafter referred to as “HR coat film 15”) having high reflectivity of the laser oscillation wavelength light is formed. The HR coat film 15 is not intended to limit the film configuration and film thickness. For example, the Al ₂ O ₃ layer 15a (thickness of about 560 mm) and the TiO ₃ layer 15b (thickness of about 430 mm) are repeated (for example, four times). ) Can be a multilayer dielectric film laminated. The HR coat film 15 is appropriately changed depending on whether the semiconductor laser device 1 is, for example, a high output type or a low output type, and the reflectance is adjusted to, for example, 50% or more. For example, in the semiconductor laser device 1 of the type in which the monitor element 13 is provided, the reflectivity of the HR coat film 15 is about 50% to 95%, and in the type in which the monitor element 13 is not provided, the reflectivity is 90% or more. It is said.

<Method for Manufacturing Semiconductor Laser Device>
Next, a method for manufacturing the semiconductor laser device 1 configured as described above will be described. The case where the semiconductor laser chip 12 is configured using the above-described AlGaInN-based compound semiconductor will be described as an example.

  First, in order to form the semiconductor laser chip 12, using a known technique, on the surface (upper surface) of the substrate 120, a laminate composed of a plurality of nitride semiconductor layers 121 to 123 as shown in FIG. Then, a wafer on which the p-type electrode 126 is formed is manufactured. Next, the back surface of the substrate 120 (the surface on which the laminated body or the like is not formed) is thinned to a predetermined thickness by, for example, polishing or etching (in this example, thinned to 40 to 150 μm). Thereafter, an n-type electrode 127 is formed on the back side of the substrate 120.

  When the stacked body of the nitride semiconductor layers 121 to 123, the p-type electrode 126, and the n-type electrode 127 are formed on the substrate 120, the wafer is cleaved into a bar state and the resonator end face 128 (FIG. 4). Reference). At this time, for example, the wafer is cleaved so that the resonator length of the semiconductor laser chip 12 is about 200 μm. This step corresponds to the end face forming step of the present invention. The wafer may be cleaved using a known technique. Further, when the resonator end face 128 is obtained, another method such as etching may be used instead of cleaving the wafer.

  Next, end face coat films 14 and 15 (AR coat film 14 and HR coat film 15) are respectively formed on the front end face 128a and the rear end face 128b (resonator end face 128) of the laser bar (LD bar) obtained by cleavage. Is deposited. This film forming step corresponds to the film forming step of the present invention. The end coat films 14 and 15 may be formed using a known technique such as a vacuum deposition method or an ECR (Electron Cyclotron Resonance) sputtering method.

  When the AR coating film 14 is formed on the front side end surface 128a and the HR coating film 15 is formed on the rear side end surface 128b, a light irradiation step of irradiating at least the HR coating film 15 of these coating films 14 and 15 is performed. Done. This light irradiation process corresponds to the light irradiation process of the present invention, and excites the crystals constituting the end face coat films 14 and 15 to generate molecular vibration and lattice vibration, thereby stabilizing the end face coat films 14 and 15. This is done for the purpose of

  FIG. 5 is a schematic diagram for explaining a light irradiation process included in the method for manufacturing the semiconductor laser device 1 according to the embodiment of the present invention. FIG. 6 is a schematic plan view showing a detailed configuration of the LD bar assembly 40 shown in FIG. 5 and is a view assuming a state viewed from above. The LD bar aggregate 40 is an aggregate obtained by collecting a plurality of laser bars (LD bars) 12 ′ on which the end face coating films 14 and 15 are formed after the wafer is cleaved.

  As shown in FIG. 5, the light irradiation step can be performed using, for example, a light irradiation device 50 and a processing chamber 51 that houses the LD bar assembly 40. As shown in FIG. 6, the LD bar aggregate 40 is obtained by bringing together a plurality of LD bars 12 ′ using a jig 52. The LD bar assembly 40 is set in the processing chamber 51 so that the HR coating film 15 of each LD bar 12 ′ is on the upper side and the AR coating film 14 is on the lower side (see FIG. 5). The HR coating film 15 of each LD bar 12 ′ is disposed in the processing chamber 51 in an exposed state. The AR coat film 14 of each LD bar 12 ′ may be disposed in the processing chamber 51 in an exposed state, or may be disposed in the processing chamber 51 in an unexposed state.

  In the processing chamber 51, a window portion 51 a is formed on the wall surface facing the HR coating film 15 so that the HR coating film 15 of each LD bar 12 ′ set in the chamber can be irradiated with light from the outside. Yes. The window 51a is preferably formed of a material exhibiting high transmittance with respect to light emitted from the light irradiation device 50, and can be made of, for example, quartz glass. The position of the light irradiation device 50 is determined so that light can be applied to the HR coating film 15 of the LD bar 12 'through the window 51a. The light from the light irradiation device 50 may be configured to be irradiated over the entire area of the HR coat film 15 by, for example, light scanning.

  The wavelength of light emitted from the light irradiation device 50 is preferably within ± 10 nm of the laser oscillation wavelength of the semiconductor laser device 1. Thereby, the effect of stabilizing the end face coat films 14 and 15 is further increased. The wavelength of the light emitted from the light irradiation device 50 is preferably selected so that the transmittance with respect to the HR coat film 15 is 5% or more. Moreover, as the light irradiation apparatus 50, for example, a semiconductor laser can be used, but the present invention is not limited to this. As the light irradiation device 50, for example, an LED (Light emitting diode) device or the like may be used. Further, the light from the light irradiation device 50 may be, for example, light obtained by dispersing white light, or fluorescence obtained by irradiating a phosphor with LED light or the like.

  Further, the processing chamber 51 may be provided exclusively for the light irradiation process, but for example, a processing chamber provided in an ECR sputtering apparatus or the like used when forming the end face coat films 14 and 15 is used. May be. As a result, the film forming process and the light irradiation process can be continuously performed, and an improvement in productivity can be expected. As a processing apparatus that provides the processing chamber 51, for example, an RF (Radio Frequency) sputtering apparatus, a digital sputtering apparatus, a P-CVD (Plasma-Chemical Vapor Deposition) apparatus, or the like may be used instead of the ECR sputtering apparatus. .

In this example, a watt class (high output) semiconductor laser that emits light having a wavelength of 405 nm which is the same as the oscillation wavelength of the semiconductor laser device 1 is used as the light irradiation device 1. The processing conditions of the light irradiation process were as follows.
(Processing conditions for the light irradiation process in this example)
Processing temperature: Room temperature Processing room atmosphere: Dry air (1 atm)
Laser output: CW (Continuous Wave) 1W
Irradiation time: Laser irradiation time per laser wavelength of 405 nm area 30 minutes

  In the light irradiation step, the process chamber 51 may be evacuated and the light irradiation may be performed while heating the LD bar 12 ′ (while the temperature in the process chamber 51 is about 200 ° C.). According to this, it is possible to prevent siloxane from being deposited on the light irradiated portion of the LD bar 12 '.

An LD bar 12 '(semiconductor laser chip 12) obtained after the light irradiation process is mounted on the stem 10, and after hermetic sealing, a burn-in process is performed by driving the device, and finally a semiconductor is tested by performing a characteristic inspection. A laser device 1 is obtained. The semiconductor chip 12 of this example has a resonator wavelength of about 200 μm, a width of about 120 μm, and a thickness of about 90 μm. Moreover, the diameter of the stem 10 of this example is φ5.6 mm. Further, the processing conditions of the burn-in process of this example were as follows.
(Processing conditions for the burn-in process in this example)
Stem temperature: 75 ° C
Optical output: CW (Continuous Wave) 60mW
Drive time: 8 hours Drive method: APC drive (using external monitor element (front monitor))

  The driving method in the burn-in process may be ACC driving instead of APC driving. In the case of APC drive, the drive current may fluctuate greatly immediately after the start of burn-in, but the drive current stabilizes over time. In the case of ACC drive, the light output may change greatly immediately after the start of burn-in, but the light output becomes stable with the passage of time.

<Results of aging test>
The semiconductor laser device 1 obtained by the above manufacturing method was subjected to an aging test under the following conditions (results are shown in FIGS. 7 and 8). As a comparative example, an aging test was performed on the semiconductor laser device manufactured under the same conditions except that the above-described light irradiation process was not performed (see FIGS. 9 and 9). 10 shows the results).
(Conditions for aging test in this example)
Stem temperature: 75 ° C
Light output: 20mW
Drive method: APC drive (using external monitor element (front monitor))

  FIG. 7 is a graph showing the change over time of the drive current (Iop) in the semiconductor laser device 1 of this example. FIG. 8 is a graph showing the change over time of the change rate of the monitor output current (Imop) and the monitor output current (Imop) in the semiconductor laser device 1 of this example, and FIG. 8 (a) shows the change over time of Imop. The graph, FIG. 8B, is a graph showing the change over time in the change rate of Imop. FIG. 9 is a graph showing the change over time of the drive current (Iop) in the semiconductor laser device of the comparative example. FIG. 10 is a graph showing the change over time of the change rate of the monitor output current (Imop) and the monitor output current (Imop) in the semiconductor laser device of the comparative example, and FIG. 10 (a) is a graph showing the change over time of Imop. FIG. 10B is a graph showing the change over time in the change rate of Imop.

  Note that the driving current (Iop) in the graph is a current necessary for emitting laser light having a predetermined optical output (optical power) from the semiconductor laser device. The monitor output current (Imop) in the graph is a current output from the monitor element 13 (rear monitor) provided in the semiconductor laser device when the semiconductor laser device is driven with the drive current. In addition, since the aging test is performed on a plurality of semiconductor laser devices at a time, a plurality of data are overlapped in the graph.

  As shown in FIGS. 7 and 9, the driving current determined by the light emitted from the front side end face 128a (the side on which the AR coating film 14 is provided) is time-dependent regardless of the presence or absence of the light irradiation process. Stable with little fluctuation. This is presumably because the AR coat film 14 was stabilized by the burn-in process performed at the time of manufacturing the semiconductor laser device.

  On the other hand, the monitor output current determined by the light emitted from the rear side end face 128b (the side where the HR coating film 15 is provided) is as time passes in this embodiment (with a light irradiation step) as shown in FIG. Stable with little fluctuation. However, as shown in FIG. 10, in the comparative example (without the light irradiation process), the monitor output current greatly fluctuates with time. This indicates that the HR coat film 15 provided on the rear side end face 128b is not stabilized only by the burn-in process, and a light irradiation process is necessary to stabilize the HR coat film 15. When the light irradiation process is performed, it is considered that in the HR coat film 15, the crystals constituting the film 15 are excited, molecular vibrations and lattice vibrations are generated, and the film 15 is stabilized.

  By employing the light irradiation process in the present embodiment, the HR coat film 15 can be stabilized without taking a long time for the burn-in process. In addition, by adopting the light irradiation process in the present embodiment, the light output in the burn-in process is reduced, and the end coat films 14 and 15 can be stabilized while suppressing damage to the semiconductor laser chip 12. Is possible. The light output in the light irradiation process is performed by using a separately prepared light irradiation apparatus 50. Therefore, the light irradiation can be performed at a relatively high output, compared with the case where the burn-in process is used. The time required for stabilization of the coating film 15 can be shortened. Furthermore, since the light in the light irradiation process is not short-wavelength light like an excimer laser, damage to the semiconductor laser chip 12 can be suppressed. As can be seen from the above, according to the manufacturing method of the semiconductor laser device of this embodiment, the production efficiency can be improved while suppressing the possibility of damaging the semiconductor laser chip (laser element) during the manufacturing.

<Others>
The embodiment described above is merely an example of the present invention, and the scope of application of the present invention is not limited to the above-described embodiment.

  For example, in the embodiment described above, the light irradiation in the light irradiation process is performed only on the HR coat film 15, but the AR coat film 14 may be irradiated with light. Whether or not the AR coating film 14 is irradiated with light may be appropriately determined depending on the conditions of the burn-in process. For example, if the conditions of the burn-in process are sufficient to stabilize the AR coat film 14, the AR coat film 14 need not be irradiated with light.

  In the embodiment described above, the monitor element 13 is built in the semiconductor laser device 1. However, the manufacturing method of the present invention is naturally applicable to a semiconductor laser device that does not include the monitor element 13. It is.

  In the embodiment described above, the semiconductor laser device is formed using a nitride III-V compound semiconductor. However, the present invention is not necessarily limited to this.

DESCRIPTION OF SYMBOLS 1 Semiconductor laser apparatus 12 Semiconductor laser chip (laser element)
13 Monitor element 14 AR coat film (first end face coat film)
15 HR coat film (second end face coat film)
128 resonator end face 128a front side end face (first end face)
128b Rear side end face (second end face)

Claims (6)

A method for manufacturing a semiconductor laser device, comprising:
An end face forming step of forming a resonator end face having a first end face used as a laser beam emitting side and a second end face facing the first end face;
A film forming step of forming a first end face coat film on the first end face and forming a second end face coat film on the second end face;
A light irradiation step of irradiating at least the second end face coat film with light among the first end face coat film and the second end face coat film;
A method of manufacturing a semiconductor laser device, comprising:   2. The method of manufacturing a semiconductor laser device according to claim 1, further comprising a burn-in step of driving a laser element constituting the device to emit light for a predetermined time after the light irradiation step.   3. The method of manufacturing a semiconductor laser device according to claim 1, wherein a wavelength of light used in the light irradiation step is within ± 10 nm with respect to an oscillation wavelength of the semiconductor laser device.   4. The method of manufacturing a semiconductor laser device according to claim 1, wherein the light used in the light irradiation step has a light transmittance of 5% or more with respect to the second end face coating film. .   5. The method of manufacturing a semiconductor laser device according to claim 1, wherein the semiconductor laser device includes a monitor element for monitoring an optical power of laser light emitted from the device.   6. The method of manufacturing a semiconductor laser device according to claim 1, wherein the semiconductor laser device is formed using a nitride-based III-V group compound semiconductor.