JP2006049548A - Semiconductor laser apparatus and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor laser apparatus having excellent laser life characteristics by removing organic matter adhering to a semiconductor laser element, a stem, and a cover etc., and also to provide its manufacturing method. <P>SOLUTION: Relatively low density plasma is produced using a parallel plane type plasma processing apparatus. Organic matter and silicon compounds adhering to a semiconductor laser element, a substrate, and electrodes etc. are removed or modified by exposing them to the produced plasma without damaging the semiconductor laser element. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a semiconductor laser device such as a nitride semiconductor laser device and a manufacturing method thereof.

  Nitride semiconductors such as GaN, AlGaN, GaInN, and AlGaInN have characteristics that they have a large band gap Eg and a direct transition semiconductor material compared to AlGaInAs semiconductors and AlGaInP semiconductors. Therefore, these nitride semiconductors are used as materials for semiconductor light-emitting elements such as semiconductor lasers capable of emitting short-wavelength light from ultraviolet to green and light-emitting diodes capable of covering a wide emission wavelength range from ultraviolet to red. It is attracting attention and is widely considered for high-density optical discs, full-color displays, and environmental and medical fields.

Further, this nitride semiconductor has higher thermal conductivity than GaAs-based semiconductors and the like, and is expected to be applied to devices operating at high temperature and high output. Furthermore, since a material corresponding to arsenic (As) in an AlGaAs-based semiconductor, cadmium (Cd) in a ZnCdSSe-based semiconductor, and its raw material (arsine (AsH ₃ )) are not used, the compound semiconductor material has a low environmental impact. Expected.

  Conventionally, when manufacturing a semiconductor laser device using a semiconductor laser element, an adhesive sheet containing an organic substance as an adhesive is used. That is, in order to obtain individual semiconductor laser elements, first, a wafer on which a plurality of semiconductor laser elements are manufactured is cleaved to form a resonator end face to have a bar shape (hereinafter referred to as an LD bar). Then, in the dividing step of dividing the individual semiconductor laser elements from the formed LD bar, when the LD bar is cleaved by forming a scribe line using a diamond pen or the like, the divided semiconductor laser elements are not separated. In addition, when the scribe line is formed on the surface opposite to the surface on which the scribe line is formed (that is, on the upper surface (front surface side) of the LD bar, the scribe line is formed on the back surface side of the LD bar or on the back surface side of the LD bar. To do so, attach an adhesive sheet to the upper surface side of the LD bar.

  Since the semiconductor laser elements thus divided are connected by the adhesive sheet, the adhesive sheet is stretched to separate the semiconductor laser elements. Thereafter, the semiconductor laser elements are picked up one by one and a chip test is performed. After the chip test is completed, the semiconductor laser elements are again attached to the adhesive sheet, picked up one by one, mounted on a heat sink, a stem, and the like, and further, a lid is attached to manufacture a semiconductor laser device.

  As described above, since the pressure-sensitive adhesive sheet containing the organic substance is used, the organic substance adheres to the manufactured semiconductor laser element. Also, organic substances may adhere to the heat sink, stem, lid, etc. during the manufacturing process. Further, in a die bonding process in which each divided semiconductor laser element is mounted on a heat sink, a stem or the like, an organic substance of Si (silicon) such as siloxane contained in the atmosphere is converted into a semiconductor laser element, a heat sink, a support, and a lid. Adhere to.

  The organic matter deposited in this way is volatilized in the atmosphere, and the volatilized organic matter causes a chemical reaction by the laser light emitted from the semiconductor laser element through the atmosphere. As a result, a substance such as an organic substance made of Si (silicon) or C (carbon) is formed on the laser emission end face having the highest light intensity by the photo-CVD (Photo Chemical Vapor Deposition) effect. Such a phenomenon uses a laser having an oscillation wavelength of 550 nm or less that has a high energy per photon and facilitates a chemical reaction, particularly a nitride semiconductor laser element that oscillates in the ultraviolet region with an oscillation wavelength of 420 nm or less. This is remarkable in a semiconductor device.

When a substance such as an organic substance is deposited on the laser emission surface, not only the output laser intensity is reduced, but also the reflectance of the laser end surface (resonator end surface) that is the laser emission surface is changed, The operating current at the time of laser driving fluctuates, and the laser life characteristics are greatly deteriorated. For such problems, the laser chip is irradiated with an energy beam such as laser light or ultraviolet light, or with plasma generated by an ECR (Electron Cycrotron Resonance) method. And a method for removing or altering the adhesive attached to the lid (see Patent Document 1).
JP 2004-40051 A

  However, if the material adhering to the semiconductor laser element, the support, the stem, etc. is removed using the technique according to the above-mentioned Patent Document 1, the cleaning cannot be performed sufficiently when an energy beam such as ultraviolet rays is irradiated. Organic matter containing (silicon) cannot be removed. Further, when the plasma generated by the ECR method is irradiated, there is a problem that damage to the semiconductor laser element is great, and after the processing, the characteristics of the semiconductor laser element are deteriorated and the life is shortened.

  In view of such problems, the present invention removes organic substances adhering to the semiconductor laser element, stem, lid, etc., and suppresses film formation on the laser emission end face due to the photo-CVD effect during the operation of the semiconductor laser element. An object of the present invention is to propose a semiconductor laser device with good laser lifetime characteristics and a method for manufacturing the same.

  In order to achieve the above object, the present invention provides a semiconductor laser device manufacturing method including a first step in which a cleaning process is performed by exposing both a stem on which a semiconductor laser element is mounted and a lid to plasma. In the plasma apparatus used for the cleaning process, two plate electrodes are installed in parallel in a reaction vessel of the plasma processing apparatus, and a high frequency power is applied to at least one of the two plate electrodes from a high frequency power source. Thus, the plasma processing apparatus is a parallel plate type plasma processing apparatus that generates plasma in a space between the two plate electrodes.

According to such a method, plasma having a relatively low plasma density (about 10 ¹⁰ cm ⁻³ ) can be generated, and the cleaning process can be performed without damaging the semiconductor laser element. Further, high frequency power may be applied to one of the two flat plate electrodes, or plasma may be generated by applying high frequency power to both of the two flat plate electrodes.

  In such a method of manufacturing a semiconductor laser device, the gas used for plasma generation in the first step may be an inert gas, a reactive gas, or a mixed gas thereof.

  Further, in such a method of manufacturing a semiconductor laser device, in the parallel plate type plasma processing apparatus used in the first step, electrodes other than the high-frequency electrode are electrically directly grounded to serve as a ground electrode. It doesn't matter.

  In the method of manufacturing a semiconductor laser device, in the first step, the stem and the lid on which the semiconductor laser element is mounted are exposed to the plasma at the same time or separately. A cleaning process may be performed.

  By such a method, impurities such as organic substances and silicon compounds can be removed or altered from the stem and the lid on which the semiconductor laser element constituting the semiconductor laser device is mounted.

  In such a method of manufacturing a semiconductor laser device, in the first step, the cleaning process is performed by placing the stem and the lid on which the semiconductor element is mounted on the high-frequency electrode and exposing the plasma to the plasma. It does not matter if it is implemented.

  Further, in such a method of manufacturing a semiconductor laser device, in the first step, the stem on which the semiconductor element is mounted and the lid body are installed on the ground electrode, and the plasma is simultaneously or separately applied to the plasma. The cleaning process may be performed by exposure.

  Further, in such a method of manufacturing a semiconductor laser device, the stem and the lid body up to an installation chamber in which the lid body is placed on the stem on which the semiconductor laser element subjected to the first step and the cleaning process is mounted. And moving the stem and the lid mounted with the semiconductor element to the installation chamber in the second step, and the stem mounted with the semiconductor element and the second step. It may be moved in an airtight box sealed with an inert gas so that the lid is not exposed to the air atmosphere.

  Further, in such a method of manufacturing a semiconductor laser device, the stem and the lid body up to an installation chamber in which the lid body is placed on the stem on which the semiconductor laser element subjected to the first step and the cleaning process is mounted. And moving the stem and the lid mounted with the semiconductor element to the installation chamber in the second step, and the stem mounted with the semiconductor element and the second step. It may be moved through an airtight moving path sealed with an inert gas so that the lid is not exposed to the air atmosphere.

  Further, in such a method of manufacturing a semiconductor laser device, the first step, the second step, and a third step of installing the lid in the installation chamber on the stem mounted on the semiconductor laser element, And in the third step, when the stem on which the semiconductor laser element is mounted is placed and fixed on the lid in the installation chamber, it is carried out in an inert gas so as not to be exposed to the atmosphere. It does not matter.

  By such a method, it is possible to prevent impurities such as organic substances and silicon compounds contained in the atmosphere from adhering to the stem and the lid on which the semiconductor element is mounted.

  According to another aspect of the present invention, there is provided a semiconductor laser device manufactured by the method for manufacturing a semiconductor laser device described above.

  In the semiconductor laser device of the present invention, the semiconductor laser element may include a nitride semiconductor layer.

  In the semiconductor laser device of the present invention, the semiconductor laser element has an oscillation wavelength of 550 nm or less.

According to the present invention, a plasma having a relatively low plasma density (about 10 ¹⁰ cm ⁻³ ) is generated by using a parallel plate type plasma processing apparatus on both the stem and the lid on which the semiconductor laser element or the like is mounted. By exposing to the generated plasma, organic substances and silicon compounds attached to the semiconductor laser element, the substrate, the electrode, and the like can be removed or altered without damaging the semiconductor laser element.

  In addition, according to the present invention, the cleaning process is performed by exposing both the semiconductor laser device, the stem on which the heat sink is mounted, and the lid to the plasma. Silicon compounds can be removed. Also, when placing and fixing the lid on the stem on which the semiconductor laser element or the like is mounted, since it is performed in an inert gas so as not to be exposed to the atmosphere, impurities consisting of organic substances and silicon compounds contained in the atmosphere It is prevented from adhering.

  As described above, the present invention prevents a chemical reaction from occurring in an organic substance, a silicon compound, or the like by laser light during operation of the semiconductor laser device, and suppresses film formation of a substance on the laser light emitting end face by the photo-CVD effect. be able to. Therefore, fluctuations in the absorption rate and reflectance of the laser beam due to the film formation on the laser beam emitting end surface are suppressed, abnormal fluctuations in the drive current of the semiconductor laser element are avoided, and the life characteristics of the semiconductor laser device are improved. Can be realized.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 3A is a top view of a stem on which a nitride semiconductor laser element is mounted via a heat sink, and a lid placed on the stem. FIG. 3B is a side view of FIG.

  In the semiconductor laser device 340, for example, the semiconductor laser element 350 is mounted in a 5.6φ can-type package including a disc-shaped stem 320 and a hollow cylindrical lid 330. One end of the lid 330 is open, and the other end is provided with an extraction window 330 </ b> A for extracting the laser emitted from the semiconductor laser element 350 to the outside of the semiconductor laser device 340. The lid 330 is made of a metal such as copper or iron, and the extraction window 330A is made of a material such as glass or plastic that can transmit a laser emitted from the semiconductor laser element 350. . Then, the lid 330 is placed so as to cover the stem 320 on which the semiconductor laser element 350 is mounted via the heat sink 310 made of SiC, and the semiconductor laser device 340 is configured.

  As shown in FIG. 3A, the semiconductor laser device 350 includes a GaN substrate 301 and a nitride semiconductor growth layer 302 that is a laminate of a plurality of nitride semiconductor thin films formed on the GaN substrate 301. A p-side electrode 303, an n-side electrode 304, and a metal multilayer film 305A. In addition, a p-side electrode 303 is formed on the surface of the nitride semiconductor growth layer 302, and on the back side of the GaN substrate 301, an n-side electrode 304 and a metal multilayer for metallization are sequentially formed from the side closer to the GaN substrate 301. Each of the films 305A is formed.

  In the semiconductor laser device 350 configured as described above, the metal multilayer film 305A on the back surface side of the GaN substrate 301 is fixed to the front surface side of the heat sink 310 via Au70Sn30 solder 312. The heat sink 310 on which the semiconductor laser element 350 is mounted is mounted and fixed on the support base 321 that is a part of the stem 320 via the SnAg3Cu0.5 solder 313 on the back surface side of the heat sink 310. Metal multilayer films 305B and 305C for metallization are formed on the front side and the back side of the heat sink 310, respectively.

  The p-side electrode 303 is electrically connected to the pin 316 via the wire 314A, and the n-side electrode 304 is electrically connected to the pin 311 via the metal multilayer film 305A, Au70Sn30 solder 312, metal multilayer film 305B, and wire 314B. . Further, insulating rings 311A and 316A are provided between the stem 320 and the pins 311 and 316, respectively. Between the pins 311 and 316 and the stem 320 and the support base 321 which is a part thereof. Are electrically insulated using insulating rings 311A and 316A. The pins 311 and 316 are electrically connected to the external connection terminals 322A and 322B that are insulated from the stem 320, and the current of the semiconductor laser element is supplied from the external connection terminals 322A and 322B. The external connection terminal 322C is electrically connected to the stem 320.

  As described above, the semiconductor laser device 340 includes the semiconductor laser element 350 and the like. Next, the semiconductor laser element 350 will be described. FIG. 4 is a schematic cross-sectional view of the semiconductor laser element. As shown in FIG. 4, the nitride semiconductor growth layer 302 is formed on the surface of the GaN substrate 301 by, for example, an n-type GaN contact layer 402, an n-type AlGaN cladding layer 403, an n-type GaN guide layer 404, and an InGaN multiple quantum. A well active layer 405, a p-type AlGaN evaporation prevention layer 406, a p-type GaN guide layer 407, a p-type AlGaN cladding layer 408, and a p-type GaN contact layer 409 are sequentially stacked.

  The p-type AlGaN cladding layer 408 and the p-type GaN contact layer 409 are provided with striped ridges extending in the resonator direction. That is, the semiconductor laser device shown in FIG. 4 has a ridge stripe structure. Further, an insulating film 410 for current confinement is provided between the p-side electrode 303 and the p-type AlGaN cladding layer 408 and the p-type GaN contact layer 409 except for the ridge portion. In the present specification, the insulating film 410 is included in the nitride semiconductor growth layer 302.

  The material used for the nitride semiconductor growth layer 302 is not limited to the above-mentioned materials, but other nitride-based compound semiconductors, for example, p-type AlGaInN is used for the p-type cladding layer, and the multiple quantum well active layer is used. GaInNAs or GaInP may be used. The clad layer may be a multilayer structure or a multiple quantum well structure. Furthermore, a crack prevention layer such as InGaN may be inserted between the n-type GaN contact layer 402 and the n-type AlGaN cladding layer 403. Further, a buffer layer may be inserted between the GaN substrate 301 and the n-type GaN contact layer 402. The ridges extending in the form of stripes in the resonator direction are not only the p-type AlGaN cladding layer 408 and the p-type GaN contact layer 409, but also the p-type GaN guide layer 407, the p-type AlGaN evaporation prevention layer 406, and the InGaN multiple quantum. The well active layer 405 may be formed by being dug up to somewhere.

  Furthermore, in this embodiment, the GaN substrate 301 is used for the production of the semiconductor laser element 350. However, the substrate material is not limited to GaN, and a mixed crystal semiconductor of InN, AlN or GaN, InN, AlN may be used. III-V group compounds such as sapphire, spinel, SiC, Si, or GaAs or GaP other than nitride may be used.

  Hereinafter, a method for manufacturing the semiconductor laser device of this embodiment will be described with reference to FIGS.

  First, a well-known technique generally used for manufacturing a semiconductor laser device is appropriately applied to grow a nitride semiconductor comprising a plurality of nitride semiconductor thin films as shown in FIG. 4 on a GaN substrate 301. A layer 302 and a p-side electrode 303 are formed. The material of the p-electrode 303 of this embodiment is Pd (15 nm) / Mo (15 nm) / Au (200 nm) from the side close to the p-type GaN contact layer 409.

  Next, the thickness of the n-type GaN substrate 301 when the layers of the nitride semiconductor growth layer 302 are stacked on the n-type GaN substrate 301 is about 350 μm, but before the n-side electrode 304 is formed, the GaN substrate 301 is formed. A part of the substrate is removed by polishing or etching from the back side of the wafer, and the thickness of the wafer is usually reduced to about 40 to 150 μm. Thereafter, Ti (30 nm) / Al (150 nm) is formed as the n-side electrode 304 from the side close to the GaN substrate 301, and Mo (8 nm) / Pt (15 nm) / Au (250 nm) is formed as the metal multilayer film 305A. Form.

In this way, the p-side electrode 303 and the n-side electrode 304 are formed, and the resonator end face of the semiconductor laser element 350 is formed by cleaving the wafer on which the layers of the multilayer body 302 made of a nitride semiconductor are laminated. At this time, the wafer is cleaved so that the cavity length of the semiconductor laser element 350 is 500 μm. The bar (LD bar) obtained by cleaving the wafer in this way is further cleaved to divide it into semiconductor laser elements 350 that are laser chips. As described above, in the dividing step of dividing the individual semiconductor laser elements 350 from the LD bar, when the LD bar is cleaved by forming a scribe line using a diamond pen or the like, the divided semiconductor laser elements 350 are separated. An adhesive sheet is stuck on the surface opposite to the surface on which the scribe line is formed. The pressure-sensitive adhesive of this pressure-sensitive adhesive sheet contains an organic substance or the like and may adhere to or remain on the divided semiconductor laser element 350. The cavity end face may be formed by etching. Further, dicing or laser ablation may be used for dividing into chips. When the characteristics of the semiconductor laser device 350 thus obtained were evaluated by pulse driving in a chip state, the threshold current density value obtained by dividing the threshold current value by the area of the ridge portion was 3.5 kA / cm ² . there were.

  The semiconductor laser element 350 thus obtained is mounted on the support base 321. Below, the mounting process implemented using the die-bonding method is demonstrated.

  As shown in FIG. 3A, Au70Sn30 solder having a layer thickness of approximately 200 μm and a sheet-like melting point of 290 ° C. is formed on the surface of the heat sink 310 on which the metal multilayer films 305B and 305C are formed on the front and back surfaces, respectively. 312 is provided. Next, the heat sink 310 is heated to a temperature slightly higher than the melting point of the Au 70 Sn 30 solder 312, and when the Au 70 Sn 30 solder 312 is melted, the semiconductor laser element 350 obtained by the above method is placed with the p-side electrode 303 side up. The n-side electrode 304 is placed on the heat sink 310 such that the n-side electrode 304 side faces the metal multilayer film 305B side of the heat sink 310. Further, while appropriately applying a load, the semiconductor laser element 350 and the heat sink 310 are well adapted to the Au 70 Sn 30 solder 312, the Au 70 Sn 30 solder 312 is solidified, and the semiconductor laser element 350 is fixed on the heat sink 310.

  Next, SnAg3Cu0.5 solder 313 having a melting point of 220 ° C. is provided on the support base 321. Then, the support base 321 is heated to a temperature slightly higher than the melting point of the SnAg3Cu0.5 solder 313, and when the SnAg3Cu0.5 solder 313 is melted, the heat sink 310 on which the semiconductor laser element 350 obtained by the above-described method is mounted, The metal multilayer film 305 </ b> C formed on the back surface is placed on the support base 321 so as to face the support base 321. Further, the heat sink 310 on which the semiconductor laser element 350 is mounted and the support base 321 are made to familiarize with the SnAg3Cu0.5 solder 313 while applying a load as appropriate. Thereafter, the support base 321 is cooled and the SnAg3Cu0.5 solder 313 is solidified to obtain the semiconductor laser element 350 fixed to the support base 321 via the heat sink 310 shown in FIG. Subsequently, using a wire bonder, the p-side electrode is electrically connected to the pin 316 via the wire 314A, and the n-side electrode 304 is electrically connected to the pin 311 via the metal multilayer film 305A, Au70Sn30 solder 312, metal multilayer film 305B, and wire 314B. Connecting.

  In this embodiment, Pd / Mo / Au is used as the material of the p-side electrode 303. However, in addition to Pd, for example, Co, Cu, Ag, Ir, Sc, Au, Cr, Mo, La, W, Al, Tl, Y, La, Ce, Pr, Nd, Sm, Eu, Tb, Ti, Zr, Hf, V, Nb, Ta, Pt, Ni and their compounds may be used. Besides Au, Ni, Ag, Ga, In, Sn, Pb, Sb, Zn, Si, Ge, Al and compounds thereof may be used, and the thickness of each layer is not limited to the above-described values. In this embodiment, Ti / Al is used as the material of the n-side electrode 304, but Hf may be used in addition to Ti, and the thickness of each layer is not limited to the above-described values.

  In this embodiment, SiC is used as the material of the heat sink 310, but any single crystal, polycrystalline, or amorphous material may be used as long as it is an insulating material such as AlN, GaAs, Si, and diamond.

  Further, the solder material provided on the surface of the heat sink 310 (the metal multilayer film 305B side) is not limited to Au70Sn30, and any solder material such as SuAgCu, In, PbSn may be used. Further, in the AuSn solder However, the ratio of Au and Sn is not limited. Further, the solder material between the back surface of the heat sink 310 (the metal multilayer film 305C side) and the support base 321 is not limited to SuAg3Cu0.5, and any of AuSn, In, PbSn, and conductive paste may be used. Also in the SuAgCu solder, the ratio of Su, Ag, and Cu is not limited. The melting point of the solder material provided on the surface of the heat sink 310 (the metal multilayer film 305B side) is higher than the melting point of the solder material between the back surface of the heat sink 310 (the metal multilayer film 305C side) and the support base 321.

  The stem 320 including the support base 321 is made of a metal mainly composed of Cu or Fe, and a Ni film / Au film or a Ni film / Cu film / Au film is plated on the surface thereof in order.

  Next, the stem 320 and the lid 330 on which the semiconductor laser element 350 shown in FIG. 3 is mounted are introduced into the chamber of the plasma processing apparatus, and plasma processing is performed using an inert gas and a reactive gas. The processing method will be described below with reference to FIGS.

As shown in FIGS. 1 and 2, the apparatus used for the plasma treatment is a parallel plate type plasma apparatus. Two parallel electrodes 3 and 5 are installed in the chamber, and a high frequency power is applied to one electrode 3 through a blocking capacitor 2 using a high frequency power source 1 so that the electrode is sandwiched between the two electrodes 3 and 5. Plasma 4 is generated in the remaining space. In this embodiment, it is assumed that another electrode 5 other than the electrode 3 to which the high frequency power is applied is electrically grounded (grounded). Usually, in such a parallel plate type plasma apparatus, plasma 4 having an electron density (= ion density) of about 10 ¹⁰ cm ⁻³ is uniformly generated on the electrode. In addition, the stem 320 on which the semiconductor laser element 350 manufactured by the above-described method is mounted and the lid 330 are separated from each other, and the parallel plate type plasma processing apparatus has two sheets on either of the electrodes. It is placed and plasma processing is performed. In this specification, the electrode 3 to which high-frequency power is applied is referred to as an “RF electrode”, and the grounded electrode 5 is referred to as a “ground electrode”.

  Using such a parallel plate type plasma processing apparatus, when an object to be processed is plasma-processed, an anode coupling method in which the object to be processed 6 is processed on the ground electrode 5 and a process on the RF electrode 3 are performed. There are two types of cathode coupling methods. As shown in FIG. 1, in the anode coupling method in which the object to be processed 6 including the stem 320 on which the semiconductor laser element 350 is mounted and the lid 330 is disposed on the ground electrode 5 for processing, the generated plasma has The treatment is performed by ions accelerated by a potential difference (about several volts) formed between a potential (plasma potential) and ground (potential = 0) and radicals that are neutral species. On the other hand, as shown in FIG. 2, in the cathode coupling method in which the object to be processed 6 is disposed on the RF electrode for processing, a bias voltage (variable) generated by applying high-frequency power to the plasma potential and the RF electrode. The treatment is performed by ions accelerated by the potential difference between them and radicals that are neutral species. In the present embodiment, the stem 320 on which the semiconductor laser element 350 is mounted and the lid 330 are subjected to plasma processing at the same time, but they may be processed separately.

Of these two types of treatment methods, in the present embodiment, cleaning using plasma is performed by an anode coupling method in which the workpiece 6 is placed on the ground electrode 5. The high-frequency power applied to the RF electrode 3 is 300 W, a gas used for plasma generation is a mixed gas of Ar (argon) gas and O ₂ (oxygen) gas (mixing ratio is 50:50), and the pressure in the chamber is Cleaning was performed by adjusting the pressure to 80 mTorr and setting the plasma treatment time to 60 seconds.

  By the plasma treatment using the mixed gas, organic substances adhering to the GaN substrate 301 constituting the semiconductor laser element 350, the p-side electrode 303 and the n-side electrode 304, the end face of the semiconductor laser element 350, or the like are removed or altered. . Thus, after the semiconductor laser element 350 is mounted on the stem 320 via the heat sink 310 or the like, cleaning is performed by exposing both the entire stem 320 on which the semiconductor laser element 350 is mounted and the lid 330 to plasma. Even if the organic matter is removed by cleaning only the semiconductor laser element 350, if the organic matter or silicon compound remains in any of the heat sink 310, the stem 320, or the lid 330 other than the semiconductor laser element 350, This is because, when the laser is emitted from the emission end face during the operation of the semiconductor laser device 340, the volatilized organic matter undergoes a chemical reaction due to the photo-CVD effect, and as a result, a film is formed on the laser light emission end face. In order to prevent this, the entire stem 320 on which the semiconductor laser element 350 is mounted and the lid 330 are both exposed to plasma for cleaning to remove organic substances or silicon compounds. Thereby, during the operation of the semiconductor laser element 350, film formation on the laser light emitting end face due to the photo-CVD effect is suppressed, and the life characteristics of the semiconductor laser element 350 can be improved.

  The lid 330 that has been cleaned by performing plasma processing in this way is placed on the stem 320 on which the semiconductor laser element 350 that has also been cleaned is mounted, for example, in a dry nitrogen atmosphere. A laser device 340 is manufactured. This also prevents the inside of the semiconductor laser element 350, the heat sink 310, the stem 320, and the lid 330 covered with the lid 330 from being shielded from the external atmosphere from being contaminated again by organic substances, silicon compounds, or the like. Is done.

  The atmosphere in which the lid 330 is installed on the stem 320 is not limited to the nitrogen described above, but is rare such as He (helium), Ne (neon), Ar (argon), or Xe (xenon). A gas atmosphere may be used. Further, the installation of the lid 330 on the stem 320 is preferably performed as soon as possible after performing the cleaning by the plasma treatment, and more preferably immediately after the cleaning.

Further, after cleaning the stem 320 and the lid 330 on which the semiconductor laser element 350 and the heat sink 310 are mounted by plasma treatment, the stem 320 and the lid 330 are installed up to the installation chamber where the lid 330 is installed on the stem 320. In order to prevent the stem 320 and the lid 330 from being contaminated by a substance that chemically reacts with a laser such as an organic substance or a silicon compound contained in the atmosphere by exposing the stem 320 and the lid 330 to the atmosphere. The body 330 is moved in an airtight box sealed with an inert gas such as N ₂ (nitrogen), He (helium), Ne (neon), Ar (argon), or Xe (xenon). It is preferable to do. Moreover, you may move along the moving path provided with the airtightness sealed with the inert gas mentioned above.

  As described above, the semiconductor laser device 340 of the present embodiment shown in FIG. 3 is manufactured. Next, five semiconductor laser devices 340 were produced, and the obtained semiconductor laser device 340 was subjected to an aging test to obtain aging characteristics. At this time, the aging test was performed under conditions of an environmental temperature of 60 ° C., a light output value fixed at 30 mW, and a direct current (DC) drive. The test results of the obtained semiconductor laser device 340 of this embodiment are shown in FIG.

  Further, as a comparative example 1 for the semiconductor laser device 340 of the present embodiment, both the stem 320 and the lid 330 on which the semiconductor laser element 350 and the heat sink 310 are mounted are not cleaned by plasma processing, and five semiconductors are used. A laser device was produced. The conditions are the same as those of the semiconductor laser device 340 of the present embodiment except that cleaning by plasma processing is not performed.

  Further, as Comparative Example 2 for the semiconductor laser device 340 of the present embodiment, both the stem 320 and the lid 330 on which the semiconductor laser element 350 and the heat sink 310 are mounted are not cleaned by plasma treatment, and a mercury lamp is used. Thus, five semiconductor laser devices that were cleaned by irradiating ultraviolet rays having a wavelength of 254 nm in an oxygen atmosphere were manufactured. The conditions are the same as those of the semiconductor laser device 340 of the present embodiment except that cleaning is performed using ultraviolet rays instead of plasma treatment.

  Further, as a comparative example 3 to the semiconductor laser device 340 of the present embodiment, an ECR plasma device that generates and maintains plasma by the ECR method on both the stem 320 and the lid 330 on which the semiconductor laser element 350 and the heat sink 310 are mounted. Five semiconductor laser devices that were introduced into the chamber and cleaned by exposing the stem 320 and the lid 330 to ECR plasma were manufactured. That is, the semiconductor laser device of this embodiment performs cleaning by exposing it to plasma by a parallel plate type plasma device, while the semiconductor laser device of Comparative Example 3 performs cleaning by exposing it to ECR plasma. is doing. Except for this, the conditions are the same as those of the semiconductor laser device 340 of the present embodiment.

  The aging test was performed on the five semiconductor laser devices of Comparative Examples 1, 2, and 3 thus fabricated in the same manner as the semiconductor laser device 340 of the present embodiment to obtain aging characteristics. At this time, the aging test was performed under conditions of an environmental temperature of 60 ° C., a light output value fixed at 30 mW, and a direct current (DC) drive. The test results of the obtained semiconductor laser devices of Comparative Examples 1, 2, and 3 are shown in FIGS.

  FIG. 5 shows the relationship between the aging time and the drive current for the five semiconductor laser devices 340 of the present embodiment. As shown in FIG. 5, a parallel plate type plasma processing apparatus is used, and a workpiece 6 including a stem 320 and a lid 330 on which a semiconductor laser element 350 and a heat sink 310 are mounted is placed on the ground electrode 5. In the semiconductor laser device 340 of the present embodiment that has been cleaned by being exposed to plasma, the operating current is maintained at an initial value even if the aging time is extended. Further, regarding the aging characteristics of the five manufactured semiconductor laser devices 340, the variation in driving current is as small as about 10 mA, and the aging characteristics are uniform. In addition, as shown in FIG. 2, even when the object to be processed 6 is cleaned by the cathode coupling method in which the object to be processed 6 is placed on the RF electrode 3 and processed, as shown in FIG. Good aging characteristics similar to those obtained when cleaning was performed by exposing the workpiece 6 to plasma by the anode coupling method were obtained.

  FIG. 6 shows the relationship between the aging time and the drive current for the five semiconductor laser devices of Comparative Example 1. In the semiconductor laser device of Comparative Example 1 in which the cleaning using the plasma processing is not performed, the driving current increases remarkably when the aging time becomes long, and the driving is performed among the five semiconductor laser devices manufactured. The variation in current is large and the aging characteristics are not uniform.

  FIG. 7 shows the relationship between the aging time and the drive current for the five semiconductor laser devices of Comparative Example 2. In the semiconductor laser device of Comparative Example 2 in which cleaning by ultraviolet irradiation was performed, the drive current increased with the aging time, although the increase in drive current was smaller than that of the semiconductor laser device of Comparative Example 1. As in Comparative Example 1, the drive current varies greatly among the five manufactured semiconductor laser devices, and the aging characteristics are not uniform.

  FIG. 8 shows the relationship between the aging time and the drive current for the five semiconductor laser devices of Comparative Example 3. As shown in FIG. 8, an ECR plasma processing apparatus is used, and an object to be processed 6 including a stem 320 and a lid 330 on which a semiconductor laser element 350 and a heat sink 310 are mounted is introduced into the chamber. In the semiconductor laser device of this embodiment that has been cleaned by exposure to plasma, one of the five semiconductor laser devices, like the semiconductor laser device 340 of this embodiment, can have a long aging time, The drive current maintains the initial value. However, for the other four semiconductor laser devices, the drive current increased rapidly within 20 hours of aging time, resulting in a rapid deterioration of the aging characteristics.

  From the results shown in FIGS. 5, 6, 7, and 8, the semiconductor laser device 340 according to this embodiment is emitted during the operation of the semiconductor laser device 340 by performing the cleaning using the parallel plate plasma described above. This prevents the chemical reaction due to the photo-CVD effect from occurring in the laser and prevents the film from being formed on the laser emission end face, and prevents fluctuations in the absorption rate and reflectivity of the laser beam due to the film formed on this emission end face. Thus, there was no abnormal fluctuation of the drive current, and aging characteristics (life characteristics) superior to those of Comparative Examples 1, 2, and 3 could be obtained.

  The cause of the difference in characteristics between this embodiment and Comparative Examples 1, 2, and 3 was examined. Regarding the semiconductor laser devices of Comparative Examples 1, 2, and 3, the lid 330 was removed from the semiconductor laser device in an inert gas or vacuum, and the surface of the semiconductor laser element 350 was analyzed by Auger electron spectroscopy. As a result, in the semiconductor laser devices of Comparative Examples 1 and 2, a large amount of C (carbon) indicating adhesion of organic substances and Si (silicon) indicating adhesion of silicon compounds was detected. Further, in the semiconductor laser device 340 of this embodiment and the semiconductor laser device of Comparative Example 3, no carbon or silicon was detected. From this result, it is considered that the semiconductor laser devices of Comparative Examples 1 and 2 did not obtain good aging characteristics because organic substances or silicon compounds adhered to the end face of the semiconductor laser element 350.

In addition, in Comparative Example 3 in which no carbon, silicon, or the like was detected by the analysis by Auger electron spectroscopy, it was considered that the good aging characteristics were not obtained because the semiconductor laser element 350 itself was damaged. . In the semiconductor laser device of Comparative Example 3, cleaning is performed using plasma by the ECR method. Normally, when plasma is generated by the ECR method, the plasma is generated at a higher density (10 ¹¹ cm ⁻⁾ than the plasma by the parallel plate method. Plasma of about ³ to 10 ¹² cm ⁻³ can be obtained. For this reason, the incident amount (flux) of ions per unit time and unit area incident from the plasma to the semiconductor laser element 350 is larger in the ECR plasma than in the parallel plate plasma. For this reason, the damage received by the semiconductor laser element 350 due to the incident ions is larger than that in the case of using a parallel plate type plasma, and it is considered that good aging characteristics cannot be obtained as shown in FIG.

  Further, in addition to the above-mentioned reasons for the poor aging characteristics of the semiconductor laser device of Comparative Example 3, the ECR type plasma has a pressure region where the plasma is generated compared to the parallel plate type plasma. For example, it is as low as several mTorr. When the pressure for generating plasma is low, the mean free path of electrons in the plasma becomes long, and the distance that the electrons are accelerated by the electric field becomes long. As a result, the electron temperature Te, which is the kinetic energy of the electrons, increases. When the value of the electron temperature Te is high, as a result, the difference between the potential of the plasma and the potential at the electrode on which the semiconductor laser element 350 is placed becomes large, and ions emitted from the plasma and incident on the semiconductor laser element 350 are increased. The accelerated energy increases. For this reason, it is considered that the damage received by the incident ions of the semiconductor laser element 350 is increased. Furthermore, a magnetic field is required when generating plasma by the ECR method. If a magnetic field is present in the plasma, the plasma density distribution is likely to be non-uniform, and for the plasma generated on the semiconductor laser element 350, if the density distribution is non-uniform, ions incident on the semiconductor laser element 350 The flux and the like vary depending on the position of the surface of the semiconductor laser element 350. As a result, a potential difference occurs in the semiconductor laser element 350, and it is considered that a large damage has occurred in the semiconductor laser element 350 due to the generated potential difference.

In this embodiment, the gas used to generate the plasma 4 is a mixed gas of Ar (argon) and O ₂ oxygen (mixing ratio is 50:50), but is not limited to this. Inert gases such as He (helium), Ar (argon), Kr (krypton), Xe (xenon) and N ₂ (nitrogen), chlorine-based gases such as O ₂ (oxygen) and CCl ₄ , fluorine such as CF ₄ System gases and mixed gases thereof may be used. Further, the mixing ratio of the mixed gas is not limited to the above-described value. The high frequency power applied to the RF electrode 3 is not limited to 300 W, and the pressure in the chamber of the plasma apparatus when generating the plasma 4 is not limited to 80 mTorr. The time is not limited to 60 seconds.

  In this embodiment, a parallel plate type plasma apparatus is used in which high-frequency power is applied to the electrode 3 on one side and the remaining electrode 5 is grounded. A flat plate type plasma apparatus may be used.

  In the above-described embodiment, the description has been made assuming that the can-type package including the stem 320 and the lid 330 is used. However, the present invention is not limited to the can-type package, and may be a carrier type, for example. The stem 320 may be mounted with a semiconductor element other than the semiconductor laser element 350, for example, a light receiving element.

  In the above-described embodiment, the semiconductor laser device 340 has been described. However, the present invention can also be applied to other semiconductor device devices using a semiconductor laser element, such as a laser coupler and an optical pickup device.

It is the schematic of the plasma processing apparatus which implements the cleaning in embodiment of this invention. It is the schematic of the modification of the plasma processing apparatus which implements the cleaning in embodiment of this invention. It is the schematic which shows the structure of the semiconductor laser apparatus in embodiment of this invention. It is a schematic sectional drawing which shows the structure of the semiconductor laser element in embodiment of this invention. It is a correlation diagram of the aging time and drive current of the semiconductor laser device in the embodiment of the present invention. It is a correlation diagram of the aging time and drive current of the semiconductor laser device in Comparative Example 1 of the present invention. It is a correlation diagram of the aging time and drive current of the semiconductor laser device in Comparative Example 2 of the present invention. It is a correlation diagram of the aging time and drive current of the semiconductor laser device in Comparative Example 3 of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 High frequency power supply 2 Blocking capacitor 3 RF electrode 4 Plasma 5 Ground electrode 6 To-be-processed object 301 GaN board | substrate 302 Nitride semiconductor growth layer 303 P side electrode 304 N side electrode 305A Metal multilayer film 305B Metal multilayer film 305C Metal multilayer film 310 Heat sink 311 Pin 311A Insulating ring 312 Au70Sn30 solder 313 SnAg3Cu0.5 Solder 314A Wire 314B Wire 316 Pin 316A Insulating ring 320 Stem 321 Support base 322A External connection terminal 322B External connection terminal 322C External connection terminal 330 Cover 330A Semiconductor window 40 Laser element 402 n-type GaN contact layer 403 n-type AlGaN cladding layer 404 n-type GaN guide layer 405 InGaN multiple Child-well active layer 406 p-type AlGaN evaporation preventing layer 407 p-type GaN guide layer 408 p-type AlGaN cladding layer 409 p-type GaN contact layer 410 insulating film

Claims (12)

In a manufacturing method of a semiconductor laser device comprising a first step of performing a cleaning process by exposing both a stem and a lid on which a semiconductor laser element is mounted to plasma,
In the plasma apparatus used for the cleaning process in the first step, two plate electrodes are installed in parallel in a reaction vessel of the plasma processing apparatus, and high frequency power is supplied from a high frequency power source to at least one of the two plate electrodes. A method of manufacturing a semiconductor laser device, which is a parallel plate type plasma processing apparatus that generates plasma in a space between two plate electrodes by applying a high frequency electrode.   2. The method of manufacturing a semiconductor laser device according to claim 1, wherein the gas used for plasma generation in the first step is an inert gas, a reactive gas, or a mixed gas thereof.   3. The parallel plate type plasma processing apparatus used in the first step, wherein electrodes other than the high-frequency electrode are electrically directly grounded to form a ground electrode. Manufacturing method of the semiconductor laser device.   2. The cleaning process is performed by exposing both the stem on which the semiconductor laser element is mounted and the lid in the first step to the plasma simultaneously or separately. A method for manufacturing a semiconductor laser device according to claim 3.   The said cleaning process is implemented by installing the said stem and the said cover body which mounted the said semiconductor element on the said high frequency electrode at the said 1st step, and exposing to the said plasma. 5. A method for manufacturing a semiconductor laser device according to any one of 4 above.   In the first step, the stem on which the semiconductor element is mounted on the ground electrode and the lid are installed, and the cleaning process is performed by exposing the plasma to the plasma simultaneously or separately. A method of manufacturing a semiconductor laser device according to claim 3. The first step, and a second step of moving the stem and the lid body to an installation chamber in which the lid body is installed on the stem on which the semiconductor laser element subjected to the cleaning process is mounted, and
In the second step, when the stem and the lid on which the semiconductor element is mounted are moved to the installation chamber, an inert gas is used so that the stem and the lid on which the semiconductor element is mounted is not exposed to the air atmosphere. The method for manufacturing a semiconductor laser device according to claim 1, wherein the semiconductor laser device is moved in a sealed and airtight box. The first step, and a second step of moving the stem and the lid body to an installation chamber in which the lid body is installed on the stem on which the semiconductor laser element subjected to the cleaning process is mounted, and
In the second step, when the stem and the lid on which the semiconductor element is mounted are moved to the installation chamber, an inert gas is used so that the stem and the lid on which the semiconductor element is mounted is not exposed to the air atmosphere. 7. The method of manufacturing a semiconductor laser device according to claim 1, wherein the semiconductor laser device is moved through an airtight sealed moving path. The first step, the second step, and a third step of installing the lid in the installation chamber on the stem mounted on the semiconductor laser element,
In the third step, when mounting and fixing the stem on which the semiconductor laser element is mounted in the installation chamber in the lid body, it is performed in an inert gas so as not to be exposed to an atmospheric atmosphere. A method for manufacturing a semiconductor laser device according to claim 1.   A semiconductor laser device manufactured by the method for manufacturing a semiconductor laser device according to claim 1.   The semiconductor laser device according to claim 10, wherein the semiconductor laser element includes a nitride semiconductor layer.   The semiconductor laser device according to claim 10, wherein an oscillation wavelength of the semiconductor laser element is 550 nm or less.

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