JP2009021548A - Light emitting element, and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor light emitting element having an improved life and stabled operation by reducing contaminants to be deposited and accumulated on a chip, while easily actualizing air-tight sealing without the need for air-tight sealing construction or strict control, and to provide a manufacturing method thereof. <P>SOLUTION: On the surface of the end face on the light emission side of the chip of the light emitting element represented by a laser chip 1, a light absorbing film 5 is formed to absorb part of emitted light. The formation of the light absorbing film 5 suppresses the deposition and accumulation of contaminants formed reacting with the emitted light. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a light emitting element and a method for manufacturing the light emitting element, and more particularly, to a semiconductor light emitting element having a short emission wavelength typified by a laser element using a nitride semiconductor and a method for manufacturing the same.

  Nitride-based semiconductors (eg, AlN, GaN, InN, etc., and AlGaN, InGaN, etc., which are solid solutions thereof) that are compounds of Group III elements Al, Ga, In, and the like and Group V elements N, are included. In the present application, these are collectively referred to as nitride-based semiconductors), and are expected to be used as materials for light-emitting elements and power devices because of their band structure and chemical stability. It is attracting attention that this nitride semiconductor is also applied to the light source.

A laser chip provided in such a laser element using a nitride semiconductor can be obtained by cleaving or dividing a wafer obtained by laminating each layer or electrode of a nitride semiconductor on a substrate. Further, on the end face obtained by cleaving the wafer, particularly on the end face on the light exit side, a single layer made of a material transparent to the emitted light (for example, SiO ₂ or Al ₂ O ₃ ) or these A protective film (low reflection film) is formed by a small number of layers combining the above. On the other hand, a protective film (high reflection film) having a high reflectivity, such as a multilayer of Al ₂ O ₃ and Ta ₂ O ₅ , is formed on the end face opposite to the end face on the light emission side. By forming the protective film in this way, the reflectance is adjusted to efficiently emit light, or the end face is prevented from being altered by a chemical reaction such as oxidation.

  In addition, there is a problem that contaminants adhere and deposit on the protective film, and this problem is particularly remarkable in a light emitting element that emits light having a short wavelength of 500 nm or less. This is because siloxane having a bond of Si and O present in the vicinity of the chip provided in the light emitting element, hydrocarbon compound, and the like are polymerized, adhered, and volumed by short wavelength light emitted from the chip, There is also a problem in light-emitting elements using the above-described nitride-based semiconductors that emit light having a short wavelength.

  The problem of contaminants adhering to and accumulating on this chip will be described with reference to the schematic side view of the laser chip in FIG. The laser chip 100 shown in FIG. 9 includes the low reflection film 101 and the high reflection film 102 described above as protective films, and the light emitted from the active layer 103 at the end face on the light emission side of the laser chip 100 is Then, the light passes through the low reflection film 102 and is emitted from the end face in a substantially vertical direction as indicated by a broken line. At this time, the contaminant 104 that has reacted to the emitted light adheres and accumulates on the low reflection film, and absorbs the emitted light. Then, it becomes necessary to increase the drive current to maintain the light emission amount, and the increase in the drive current causes deterioration of the element life and instability of the operation of the light emitting element.

  As a specific example, FIG. 10 shows a result of an operation test of a laser element including the laser chip 100 shown in FIG. FIG. 10 is a graph in which a laser element with an oscillation wavelength of 405 nm is continuously oscillated by controlling the drive current so that the light output is 15 mW and the temperature is constant at 75 ° C. As shown in FIG. 10, since the pollutant 104 in the atmosphere gradually adheres and accumulates after the oscillation starts and becomes thicker, the drive current increases as the drive time elapses. Specifically, the current value immediately after the start of operation is about 60 mA, but the current value after driving for 500 hours has increased to about 150 mA, which is twice or more. Further, the drive current fluctuates up and down in units of several tens of mA, and the operation is unstable.

In order to prevent this problem, a method has been proposed in which a chip is hermetically sealed with a cap, for example, as in a can package, and the contamination atmosphere is controlled by controlling the atmosphere in which the chip is hermetically sealed (see Patent Document 1). ). In addition, a method of removing contaminants by cleaning with plasma before hermetically sealing, and a method of removing contaminants by providing an adsorbing member that adsorbs contaminants in a hermetically sealed package are proposed. (See Patent Document 2 and Patent Document 3).
JP 2003-289010 A JP 2004-040051 A JP 2004-014820 A

  However, in these methods, it is necessary to strictly control the atmosphere for hermetic sealing and a configuration for hermetic sealing is required, which causes a problem that the light emitting element becomes enormous. When it is applied to a light source for an information recording apparatus typified by an optical pickup such as a CD (Compact Disk) or a DVD (Digital Versatile Disk), it becomes difficult to adapt due to the size of the light emitting element. Further, if the structure of the light emitting element is a frame package that does not hermetically seal, it can be easily applied to an optical pickup. However, as the usage time passes, the contaminant 104 as shown in FIG. As the film is deposited, there arises a problem that the element life is deteriorated or the operation becomes unstable.

  Even if a package that hermetically seals the chip is adopted, it is necessary to use an organic adhesive such as Ag paste, silicone or epoxy in the package. Volatilizes and becomes a pollutant. About this, for example, by irradiating with plasma or the like before the hermetic sealing, the contaminants are removed, or the hermetic sealing is performed in dry air having a dew point of −15 ° C. or lower to suppress contamination. Although the adhesion and deposition of contaminants can be prevented to some extent, the manufacturing process becomes complicated because it is necessary to perform strict management of plasma irradiation and sealing atmosphere. Further, since contaminants may later volatilize in the sealing atmosphere due to heat during operation of the device, it is difficult to completely prevent the adhesion and deposition of contaminants. In addition, a process for confirming whether or not airtight sealing has been performed is necessary, and a light emitting element that has not been securely airtightly sealed has to be discarded, resulting in a decrease in yield.

  Therefore, the present invention reduces the contaminants attached to and deposited on the chip to increase the life of the light-emitting element and stabilize the operation, and does not require a hermetically sealed configuration, or involves strict control. It is an object of the present invention to provide a light emitting element that can be hermetically sealed easily and a method for manufacturing the light emitting element.

  In order to achieve the above object, a light emitting device of the present invention is a light emitting device including a chip that emits light, and a part of the emitted light is placed on the outermost surface on the end surface from which the light of the chip is emitted. A light absorbing film that absorbs the light is provided.

  Further, in the light emitting element, the chip is formed on an end face from which the light of the chip is emitted and includes a protective film that protects the end face, and the light absorption film is formed on a surface of the protective film. It does not matter as well.

  In the above light emitting device, the protective film may include an oxide film made of an oxide containing at least one element selected from the group consisting of aluminum, titanium, yttrium, silicon, niobium, hafnium, and tantalum. I do not care.

  In the above light-emitting element, the protective film may include a film containing at least one compound of aluminum nitride, silicon nitride, aluminum oxynitride, and silicon oxynitride. Further, aluminum nitride or aluminum oxynitride may be formed on the end face of the chip.

  In the above light emitting device, the light absorption film may include a metal film made of metal, and the metal film is selected from the group consisting of gold, platinum, rhodium, iridium, osmium, ruthenium and palladium. It does not matter if it contains at least one element. Furthermore, the metal film may be an alloy film formed by combining two or more metal elements, or may be a composite film formed by stacking a plurality of metal films.

  In the above light emitting device, the outermost surface of the composite film may be formed of a film containing at least one element selected from the group consisting of gold, platinum, rhodium, iridium, osmium, ruthenium and palladium. Since these films have a low adhesion coefficient of a Si-based substance that is one of the contaminants, the adhesion of the contaminants can be suppressed.

  In the above light-emitting element, the light absorption film is made of an oxide containing at least one element selected from the group consisting of aluminum, titanium, zirconium, yttrium, silicon, niobium, hafnium, tungsten, and tantalum, and has a stoichiometric amount. An oxygen-deficient film having a composition with less oxygen than the theoretical composition may be provided.

  In the above light emitting device, the light absorption film may be a nitride film made of a nitride containing at least one element selected from the group consisting of aluminum, titanium, zirconium, yttrium, silicon, niobium, hafnium, tungsten, and tantalum. It does not matter as a provision.

  With such a configuration, aluminum nitride or aluminum oxynitride adheres to the end face of the chip with good adhesion, so that the protective film can be prevented from being peeled off and the yield can be improved. Further, it becomes possible to prevent the end face from being altered, and the end face can be prevented from being broken. Further, by providing silicon nitride or silicon oxynitride having a small thermal expansion coefficient and good hygroscopicity, it is possible to prevent an increase in driving current when operating at a constant light output.

  In the light emitting element, the chip may be a laser chip that emits laser light.

  In the above light-emitting element, the light-emitting element may be configured not to hermetically seal the chip, or may be configured to include the chip in a frame package.

  In the above light emitting device, the light emitting device may be provided with the chip being hermetically sealed in an HHL package, or may be provided with the chip being hermetically sealed in a can package.

  In the above light-emitting element, the light-emitting element may be provided with the chip hermetically sealed together with an adhesive containing an organic substance.

  In the light emitting device, the chip may include a layer made of a nitride semiconductor.

  The light emitting device manufacturing method according to the present invention is a method for manufacturing a light emitting device including a laser chip that emits laser light, and a protective film that protects the end surface of the laser chip that serves as an end surface that emits laser light. And a second step of forming a light absorption film that absorbs part of the laser light emitted from the laser chip on the surface of the protective film after the first step. It is characterized by.

  In the above-described method for manufacturing a light-emitting element, a third step of mounting the laser chip without hermetically sealing may be further provided.

  In the above light emitting device, the light absorption film is made of metal, and at least a part of the light absorption film is a non-uniform region where the thickness in the region is non-uniform, and is emitted from the chip. At least a part of the light may be emitted through at least a part of the non-uniform region.

  With this configuration, light can be efficiently transmitted through a thin portion of the light absorption film in the non-uniform region. That is, by partially thinning the light absorption film, it is possible to suppress the light absorption, improve the slope efficiency, and reduce the drive current. On the other hand, since the light absorption film is partially thinned, a thick part is also provided. Therefore, it is possible to prevent the effect of providing the light absorption film, that is, the effect of suppressing adhesion and deposition of contaminants from being impaired.

  In the above light emitting device, the non-uniform region of the light absorption film may be a discontinuous region where the light absorption film is discontinuous.

  By constituting in this way, the portion which becomes discontinuous, that is, the thickness becomes 0, is included in the non-uniform region. Therefore, it becomes possible to emit light more efficiently.

  In the above light emitting device, the discontinuous region of the light absorption film may be a region including the metal particles forming the light absorption film.

  By comprising in this way, it becomes possible to form a discontinuous area | region by aggregating and granulating the metal which comprises a light absorption film. That is, it is possible to easily form a light absorption film having a discontinuous region simply by aggregating the metal constituting the light absorption film.

  Further, in the light emitting device, the non-uniform region of the light absorption film includes a layer in which the metal forming the light absorption film is continuous, and a grain made of the metal formed on a surface of the layer. It does not matter as long as it is an area.

  Even in such a configuration in which a continuous layer exists, the same effect as in the case where the above-described discontinuous region is provided can be obtained. That is, light can be emitted efficiently.

  In the above light emitting device, the metal may contain at least one element selected from the group consisting of gold, platinum, rhodium, iridium, osmium, ruthenium and palladium.

  In the above light emitting device, the light absorption film may be made of palladium oxide.

  In the above light emitting element, the light emitting element may be configured not to hermetically seal the chip, or the light emitting element may be configured to include the chip in a frame package. .

  The light emitting device of the present invention is characterized in that in the light emitting device including a chip that emits light, a metal film made of a metal is provided on the outermost surface on the end surface from which the light of the chip is emitted.

  In the above light emitting device, at least a part of the metal film may be a region in which the metal forming the metal film is granular, and the metal film is a continuous layer. It does not matter.

  According to the configuration of the present invention, since the light absorption film that absorbs part of the light emitted on the end surface that emits the light is formed, the light of the light emitting element is emitted on the light absorption film. It is possible to prevent the contaminants from adhering and depositing on the end face. Therefore, it is possible to prevent the light output of the emitted light from being reduced due to the adhesion and deposition of such contaminants. In addition, since it is not necessary to increase the drive current in order to maintain the light output, the life of the light emitting element can be extended.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. First, the basic configuration of the present invention will be described, and then various examples will be described.

<< Basic configuration >>
First, the basic configuration of the present invention will be described with reference to FIG. FIG. 1 is a schematic side view showing an example of the configuration of a laser chip in the present invention, and corresponds to FIG. 9 showing the configuration of a conventional laser chip.

  As shown in FIG. 1, in the present invention, a low-reflection film 3 is provided on the end surface of the laser chip 1 from which laser light is emitted from the active layer 2, and a high-reflection film is provided on the end surface opposite to the end surface on the light emission side. In particular, the light absorption film 5 is formed on the surface of the low reflection film 3 formed on the end face on the light emitting side. Conventionally, the low reflection film 3 has been formed on the end surface on the light emitting side using only a material transparent to the emitted light so as not to reduce the amount of emitted light. A light absorption film 5 made of a material that is not transparent to the emitted light is formed on the surface of the low reflection film 3.

  Examples of the light absorption film 5 include a metal film containing gold (Au), platinum (Pt), rhodium (Rh), iridium (Ir), osmium (Os), ruthenium (Ru), palladium (Pd), and the like. Nitrides such as aluminum (Al), titanium (Ti), zirconium (Zr), yttrium (Y), silicon (Si), niobium (Nb), hafnium (Hf), tungsten (W), and tantalum (Ta). Nitride film including aluminum (Al), titanium (Ti), zirconium (Zr), yttrium (Y), silicon (Si), niobium (Nb), hafnium (Hf), tungsten (W), tantalum It is possible to use an oxygen-deficient film that is an oxide such as (Ta) and has a composition shifted from the stoichiometric composition in a direction in which oxygen decreases. .

  Next, an example of the operation of the laser element including the laser chip on which the light absorption film 5 is formed will be described with reference to FIG. FIG. 2 is a graph showing a result of an operation test of a laser element including the laser chip 1 having the configuration shown in FIG. 1, and corresponds to FIG. 10 showing a result of an operation test of a conventional laser element. Further, FIG. 2 shows a laser element having an oscillation wavelength of 405 nm, the drive current is controlled to be constant at an optical output of 20 mW and a temperature of 75 ° C., and the laser chip 1 is not hermetically sealed. It is a graph at the time of carrying out continuous oscillation in the inside.

  As shown in FIG. 2, by forming the light absorption film 5 in the present invention on the surface of the low reflection film 3, it is possible to suppress an increase in the drive current with the lapse of the drive time and to reduce the drive current. It can be stabilized. In the case of this example, although the light output is increased from 15 mW in the case of FIG. 10 and the contaminants are likely to react, the drive current hardly fluctuates after the start of oscillation and remains constant at about 80 mA. And it is a stable value.

  This is because a part of the emitted light is absorbed by the light absorption film 5 to re-evaporate the attached pollutant, or the adherence of the pollutant itself is prevented. It is thought that the adhesion and deposition of pollutants are suppressed. Further, by suppressing the adhesion and deposition of contaminants, it is possible to prevent an increase in driving current accompanying a decrease in the amount of light emitted even if the laser element is driven for a long time, and to extend the life of the laser element. it can.

  Further, by forming the light absorption film 5 according to the present invention on the laser chip 1, even if the laser chip 1 is mounted in various packages without hermetic sealing, the driving current increases with the lapse of driving time. Can be suppressed. In addition, a package that does not perform hermetic sealing can be adopted even in a laser element that emits light having a short wavelength, and the laser element can be downsized. Further, even when a package that requires hermetic sealing is adopted, it is not necessary to strictly control sealing conditions such as a dew point, so that a laser element can be easily manufactured.

  Note that specific configuration examples and effects of the chip on which these light absorption films 5 are formed will be described in detail in the embodiments described later. Moreover, the material of the light absorption film 5 described above is an example, and other materials can be used as the light absorption film 5. Further, the light absorption film 5 may be a multilayer film.

  The present invention can be applied to all light emitting elements that emit light having a short wavelength, and may be applied to a chip of a light emitting element such as a light emitting diode or a super luminescence diode in addition to the laser chip 1. Further, even when applied to a laser chip, the present invention is applied only to an edge-emitting laser chip that emits light from the end face of the laser chip as described above (a plane perpendicular to the growth surface on which each layer of the substrate is grown). In addition, the present invention may be applied to a surface emitting laser chip that emits light from a surface perpendicular to the end surface of the chip (a surface parallel to a surface on which each layer of the substrate is grown). In any case, by forming the light absorption film 5 on the outermost surface of the end surface from which light is emitted, it is possible to prevent the contaminants from adhering and depositing on the outermost surface.

  Further, the present invention can also be applied to a chip that outputs light having a short wavelength included in an element formed by combining a plurality of elements. For example, in a hologram laser including a laser chip together with an optical element such as a hologram element or a light receiving element, a light emitting element that includes a chip that emits light of a short wavelength and a fluorescent plate, and outputs light in which a plurality of wavelengths such as white are mixed. It may be applied to the chip provided.

  In addition, any light-emitting element made of a material that emits light having a short wavelength can be applied without being limited to nitride-based semiconductors. For example, the present invention may be applied to a light emitting element made of a material such as ZnSe or ZnO.

Further, a hexagonal semiconductor film such as an AlN film may be directly formed on the end face. By configuring in this way, the effect of preventing the peeling by adhering the protective film, the effect of stabilizing the operation especially when the output is particularly high because the end face is more firmly protected by the protective film being adhered, Can be obtained. This effect will be described with reference to the graph of FIG. FIG. 4 shows a laser device including a laser chip 30 having a configuration in which an AlN film 32 as shown in FIG. 3 is formed on an end face on the light emission side and a low reflection film 33 made of Al ₂ O ₃ is formed thereon. It is a result of an operation test. In addition, FIG. 4 shows a laser device having an oscillation wavelength of 437 nm, the drive current is controlled so that the light output is 15 mW, the temperature is constant at 75 ° C., and continuous oscillation in an air atmosphere without hermetic sealing. This is a graph.

  As shown in FIG. 4, the laser chip 30 having the AlN film 32 formed on the end face operates stably without causing breakdown for 1000 hours or more even when the optical output is 15 mW and the drive current exceeds 150 mA. Is possible. However, as shown in FIG. 3, since the laser chip 30 is configured not to include the light absorption film 5 shown in FIG. 1 in order to distinguish it from the effect of the present invention, the drive current rises as the drive time elapses. ing. Specifically, the drive current increases by about 30 mA in 500 hours from the start of oscillation. However, if the light absorption film 5 according to the present invention is formed on the surface of the low reflection film 33 having the configuration shown in FIG. 3, an increase in current with the passage of drive time is prevented as shown in FIG. It becomes possible.

  Further, by reducing the reflectivity of the high reflection film 4 shown in FIG. 1, a small amount of light is also output from the high reflection film 4 side of the laser chip 1, and a control signal based on the output small amount of light is fed back. Thus, when the light emitting element is configured to control the drive current, the light absorption film 5 may be formed on the surface of the highly reflective film 4.

  With this configuration, it is possible to prevent contaminants from adhering to and depositing on the surface of the highly reflective film 4, so that the light output for creating the control signal can be accurate. it can. Therefore, the fact that the light output from the highly reflective film 4 side is weakened due to the attachment and deposition of contaminants is mistakenly recognized as the light emission from the light emitting element is weakened, and an inappropriately large current is supplied to the light emitting element. It becomes possible to prevent this.

  Further, when a metal film is used as the light absorption film 5, if a metal film is directly formed on the end face, a current may be short-circuited through the metal film and the current may not flow to the active layer. In addition, the heat generated from the light absorption film 5 is not limited to the metal film, and the end face may be damaged. Therefore, it is not preferable to form the light absorption film 5 near the end face. Furthermore, since the place where the contaminant adheres is on the surface of the protective film 3, 4, the adhesion and deposition of the contaminant are more prevented when the light absorption film 5 is formed near the surface of the protective film than near the end face. This is preferable because it is possible.

<< Example >>
Next, an embodiment of the present invention having the above basic configuration will be described. Each of the embodiments described below is merely an example, and as described above, the present invention has any configuration as long as the light absorption film is provided on the outermost surface on the end surface from which the light of the chip is emitted. It doesn't matter.

<First Example>
First, the first embodiment will be described with reference to FIG. FIG. 5 is a schematic perspective view and side view showing an example of the configuration of the laser chip in the first embodiment. First, as shown in the perspective view of FIG. 5A, the laser chip 10 in this example includes a buffer layer 12 made of n-type GaN having a thickness of 0.2 μm and stacked on an n-type GaN substrate 11; An n-type cladding layer 13 made of n-type Al _0.06 Ga _0.94 N having a thickness of 2.3 μm stacked on the buffer layer 12 and an n-type GaN having a thickness of 20 nm stacked on the n-type cladding layer 13. Multi-quantum well activity in which a 4 nm-thick InGaN layer and a 8 nm-thick GaN layer are stacked on a GaN / InGaN / GaN / InGaN / GaN / InGaN / GaN layer on the n-type guide layer 14 and the n-type guide layer 14 the layer 15, a protective layer 16 made of GaN having a thickness of 70nm is stacked on the multiple quantum well active layer 15, made of p-type Al _0.3 Ga _0.7 N having a thickness of 20nm is stacked on the protective layer 16 A flow blocking layer 17, a p-type cladding layer 18 in which the upper while being stacked on the current blocking layer 17 made of p-type Al _0.05 Ga _0.95 N to a stripe shape extending in a predetermined direction, of the p-type cladding layer 18 And a p-type contact layer 19 made of p-type GaN having a thickness of 0.1 μm and stacked on the striped portion.

  These layers 12 to 19 are formed by epitaxial growth on the substrate 11 in order, and a striped ridge stripe 20 comprising a part of the p-type cladding layer 18 and the p-type contact layer 19 is formed by the p-type contact layer 19. After the layers 12 to 19 are epitaxially grown in order, the p-type cladding layer 18 and the p-type contact layer 19 are removed by etching. In addition, the oscillation wavelength of the laser chip 10 in this example is 405 nm, and the width of the ridge stripe 20 is a value between 1.2 μm and 2.4 μm, for example, a value of about 1.5 μm. In the case of a broad area laser used for illumination or the like, the width of the ridge stripe 20 may be about 3 μm to 50 μm. Further, as shown in FIG. 5A, a mesa-shaped ridge stripe 20 may be used.

Further, the laser chip 10 has an insulating film 21 made of SiO ₂ / TiO ₂ formed so as to fill both sides of the ridge stripe 20 and a p made of Pd / Mo / Au formed on the ridge stripe 20 and the insulating film. An electrode 22 and an n electrode 23 made of Hf / Al formed on the surface of the substrate 11 opposite to the surface on which the buffer layer 12 is laminated are provided.

  As will be described later, a surface (surface A and surface B) substantially perpendicular to the extending direction of the ridge stripe 20 is provided with a protective film and a light absorption film formed on the protective film. In this embodiment, the low reflection film 3 and the light absorption film 5 as shown in FIG. 1 are formed with the surface A as the end surface on the light emission side, and the high reflection film 4 is formed on the surface B. I will do it.

  For the lamination of the nitride semiconductor layers 12 to 19 provided in the laser chip 10, the MOCVD (Metal Organic Chemical Vapor Deposition) method may be used, the MBE (Molecular Beam Epitaxy) method, the HVPE (Hydride Vapor) method, or the like. A method such as Phase Epitaxy method can be used. For forming the insulating film 21 and the protective films 3 and 4, various sputtering methods such as a magnetron sputtering method, an ECR (Electron Cyclotron Resonance) sputtering method, and a PECVD (Plasma Enhanced Chemical Vapor Deposition) method can be used. In addition, the metal films such as the electrodes 21 and 22 can be formed by various deposition methods such as EB (Electron Beam) deposition method, resistance heating deposition method, and the above-described various sputtering methods. The light absorbing film 5 may be formed by appropriately selecting from these methods according to the type of material used for the light absorbing film.

Further, the structures of the protective film and the light absorption film are shown in the side view of FIG. As shown in FIG. 5B, as the low-reflection film 3, an aluminum oxynitride (AlO _x N _1-x (where 0 <x <1)) film 3a and silicon nitride (SiN) film are sequentially formed from the surface A. 3b, an aluminum oxide (Al ₂ O ₃ ) film 3c is formed. The thickness of the AlO _x N _1-x film 3a is 20 nm, the thickness of the SiN film 3b is 200 nm, and the thickness of the Al ₂ O ₃ film 3c. Is 140 nm. The light absorbing film 5 is made of palladium (Pd) and has a thickness of 3.5 nm.

On the other hand, the high reflection film is formed by sequentially forming the AlO _x N _1-x film 4a and the SiN film 4b from the surface B, and further combining four sets of the silicon oxide (SiO ₂ ) film 4c and the titanium oxide (TiO ₂ ) film 4d. The films are sequentially formed from the SiO ₂ film 4c. Then, an SiO ₂ film 4e is further formed on the fourth set of TiO ₂ film 4d. At this time, the thickness of the AlO _x N _1-x film 4a is 20 nm, the thickness of the SiN film 4b is 80 nm, the thickness of the combined SiO ₂ film 4c is 71 nm, and the thickness of the TiO ₂ film 4d is 46 nm. The thickness of the SiO ₂ film 4e formed on the fourth set of TiO ₂ film 4d is 142 nm.

  Here, regarding an example of the method for forming the protective films 3 and 4 and the light absorbing film 5 described above, when the ECR sputtering method is used for forming the protective films 3 and 4 and the EB vapor deposition method is used for forming the light absorbing film 5 Will be described as an example. First, in order to form the low reflection film 3 on the end face on the light emitting side, a bar obtained by cleaving the wafer is inserted into the film forming chamber of the ECR sputtering apparatus. Here, the bar represents a state in which a plurality of laser chips shown in FIG. 5 are integrally connected, and the ridges extend so that the plurality of laser chips 10 align the surfaces A and B. A plurality connected in a line in a direction substantially perpendicular to the direction is represented. Then, the laser chip 10 is obtained by dividing this bar for each laser chip 10 shown in FIG. Note that the laser chip 10 may be divided before the protective film is formed.

When the bar is inserted into the ECR sputtering apparatus, nitrogen gas is introduced at a flow rate of 5.2 ccm, and oxygen gas is also introduced at a flow rate of 0.1 ccm. Then, argon gas is introduced at a flow rate of 20.0 ccm to generate plasma. Further, an RF (Radio Frequency) power of 500 W is applied to the Al target, and a microwave power of 500 W is applied to generate argon plasma, thereby forming the AlO _x N _1-x film 3a. Note that x can be controlled by appropriately changing the flow rates of nitrogen gas and oxygen gas.

Next, the SiN3b film is formed by switching the target to Si and flowing 5 ccm of nitrogen gas. Then, the target is switched to Al again, and oxygen gas is allowed to flow at 5.8 ccm to form the Al ₂ O ₃ film 3c. At this time, argon gas was flowed at 20.0 ccm, RF power of 500 W was applied to the Si and Al targets, and 500 W of microwave power was applied to generate argon plasma.

  Then, the bar on which the low reflection film 3 is formed is taken out from the ECR sputtering apparatus, and the light absorption film 5 made of Pd is formed at a temperature of about 150 ° C. by the EB vapor deposition apparatus. Note that the light absorption film 5 may be formed continuously with respect to the formation of the low reflection film 3 by using an ECR sputtering apparatus without using the EB vapor deposition apparatus.

Further, the high reflection film 4 is formed in the same manner, and four combinations of the AlO _x N _1-x film 4a, the SiN film 4b, the SiO ₂ film 4c, and the TiO ₂ film 4d are sequentially formed using an ECR sputtering apparatus. _Two films 4e are formed in order. And the laser chip 10 as shown in FIG. 5 is obtained by dividing | segmenting the bar | burr in which the protective films 3 and 4 and the light absorption film 5 were formed.

  Next, an example of a laser element on which the obtained laser chip 10 is mounted will be described. In this embodiment, the case of mounting on a frame package which is not hermetically sealed will be described with reference to FIG. FIG. 6 is a schematic perspective view of the laser element in the present embodiment.

  As shown in FIG. 6, the laser element 60 in this embodiment includes a laser chip 10, a submount 61 to which the laser chip 10 is fixed, a frame 62 to which the submount 61 is fixed, and a frame 62 integrated with the frame 62. Radiating fins 63 provided at both ends of 62, lead pins 64 for supplying power to the laser chip 10, and resin molds 65 for holding the lead pins 64 a to 64 c and the frame 62 together.

  The submount 61, the frame 62, and the heat radiating fins 63 are made of a metal material such as copper or iron, and the heat generated in the laser chip 10 is transmitted to the frame 62 and the heat radiating fins through the submount 61 to be radiated. It has become. In the present embodiment, three lead pins 64 a to 64 c are provided. The center lead pin 64 b is connected to the frame 62, and the two lead pins 64 a and 64 c at both ends are fixed by the resin mold 65. The frame 62 is integrated.

  The result of the drive test when power is supplied to the laser device 60 configured as described above to cause continuous oscillation is the graph of FIG. 2 shown in the basic configuration of the present invention. Therefore, even when the laser element 60 is not hermetically sealed, it is possible to prevent the adhesion and deposition of contaminants, and it is necessary to increase the drive current as the drive time elapses, resulting in a shortened element life. It is possible to prevent the operation from becoming unstable.

  Further, in this embodiment, since the configuration for hermetically sealing the laser chip 10 is unnecessary, the laser element 60 can be downsized. Therefore, it can be easily applied to a light source for an information recording apparatus typified by a CD or DVD optical pickup.

<Second embodiment>
Next, a second embodiment will be described with reference to FIG. In this embodiment, the laser chip is mounted on a can package that requires hermetic sealing of the laser chip, and FIG. 7 is a schematic perspective view of the laser element in this embodiment. Note that the laser chip 10a used in this embodiment has substantially the same structure as the laser chip of FIG. 5 shown in the first embodiment, but the reflectance of the high reflection film 4 is about 70% to 80%. It is assumed that the design has been changed such that the number of films forming the highly reflective film 4 is reduced or the thickness of some of the films is changed compared to the laser chip 10 shown in FIG. .

  In this embodiment, it is assumed that a light absorption film is formed not only on the surface of the low reflection film but also on the surface of the high reflection film. This film is made of Pd and has a thickness of 4 nm as in the first embodiment.

  As shown in FIG. 7, the laser element 70 in this embodiment includes a laser chip 10a, a submount 71 to which the laser chip 10a is fixed, a block portion 72 to which the submount 71 is fixed, and a height of the laser chip 10a. A photodiode 73 that receives light emitted from the reflective film side to create a control signal, a pin 75a that is electrically connected to the photodiode 73 by a wire 74a, and a laser chip 10a that is electrically connected by a wire 74b. A pin 75b, a block portion 72 and a photodiode 73 disposed on one surface, and pins 74a and 75b disposed through the other surface opposite to the one surface, A pin 74c which is connected to the other surface of 76 and serves as a common electrode of the photodiode 73 and the laser chip 10a; Includes a cap 77 for hermetically sealing connected to one side of 76, the glass window 78 the light emitted from the low-reflection film side of the laser chip 10a is transmitted together provided in the cap 77, the. Moreover, the block part 72 and the stem 76 are integrally molded, and are made of a metal material such as copper or iron. The cap 77 and the pins 74a to 74c are the same, and are made of a metal material.

  In this configuration, the laser chip 10a and the submount 71 are bonded by solder, and the submount 71 and the block portion 72, and the photodiode 73 and the stem 76 are connected using Ag paste. Electrically connected. Since the Ag paste contains an organic adhesive, even if the cap 77 is adhered to the stem 76 for hermetic sealing, the organic substance will drift in the sealing atmosphere. In the case of a conventional laser device configuration, the dew point of the dry air to be hermetically sealed is strictly set in order to reduce the problem that this organic matter becomes a contaminant and adheres to and accumulates on the light emitting side end face of the laser chip. (For example, −35 ° C. or lower).

  However, if the light absorbing film is provided on the surface of the protective film of the laser chip 10a as in the present embodiment, even if an organic substance is drifting in the sealing atmosphere, it becomes a contaminant and adheres as described above. Accumulation can be prevented. Accordingly, it is possible to perform hermetic sealing without strictly controlling the sealing atmosphere and suppressing the vapor pressure of the organic matter. Therefore, the manufacturing process can be simplified. Moreover, even if other organic adhesives such as epoxy and silicone are used in addition to the Ag paste, it is possible to prevent the adhesion and deposition of contaminants, so that the degree of freedom in designing the package can be ensured. it can.

  In the present embodiment, the photodiode 73 receives the light emitted from the high reflection film side of the laser chip 10a to generate a control signal and to a driving device (not shown) of the laser element 70 via the pin 75a. It is configured to provide feedback. Therefore, there is a possibility that contaminants may adhere and deposit on the side of the highly reflective film where light is emitted, but in this embodiment, the light absorbing film is also formed on the surface of the highly reflective film. Adhesion and deposition are prevented.

  Therefore, the light received by the photodiode 73 is not affected by the pollutant, and an erroneous control signal can be prevented from being fed back to the driving device. In particular, the fact that the light output from the highly reflective film side is weakened due to the adhesion and deposition of contaminants is mistakenly recognized as a decrease in the output of the laser element 70, and an inappropriately large current is supplied to the laser element 70. Can be prevented.

  In the configuration of the laser element 70 shown in FIG. 7, the laser chip 10a and the submount 71 are directly connected to the submount 71 and the block portion 72, respectively, and are also electrically connected. Although it is configured, the laser chip 10a and the block unit 72 may be electrically connected using a wire.

  In addition, solder may be used instead of using Ag paste for the connection between the submount 71 and the stem 76 and the photodiode 73 and the stem 76. In such a configuration, conventionally, there is no risk of volatilization of the organic adhesive contained in the Ag paste, so it is not necessary to control the vapor pressure of the organic adhesive in the sealing atmosphere. It was possible to obtain an effect that the control of the dew point of the dry air to be stopped can be slightly relaxed (for example, −15 ° C. or lower).

  On the other hand, in the configuration of the present invention, since the dew point control itself can be fundamentally unnecessary, the manufacturing process is significantly larger than the case where solder is used instead of Ag paste as in this example. Can be simplified. In addition, whether or not Ag paste is used, stable operation cannot be performed unless the hermetic seal (for example, by welding) between the cap 77 and the stem 76 is sufficient. A confirmation step for strictly confirming whether or not the hermetic sealing is sufficient was required, and the yield was low. However, with the structure of the present invention, even if the hermetic sealing is insufficient, the adhesion and deposition of contaminants can be prevented, so that the confirmation process can be reduced and the yield can be improved.

<Third embodiment>
Next, a third embodiment will be described with reference to FIG. In this embodiment, a laser chip 10 similar to the laser chip 10 in the first embodiment is mounted on an HHL (High Heat Load) package that requires hermetic sealing. FIG. 8 is a schematic perspective view of the laser element in the present embodiment. In addition, this HHL package is a package which enables the high output of the watt class used for uses, such as illumination.

  As shown in FIG. 8, the laser element 80 in this embodiment includes a plurality of laser chips 10, a submount 81 to which the laser chip 10 is fixed, a heat spreader 82 to which the submount is fixed and radiates heat, A wiring board 83 provided with wiring for supplying power to an element provided in the package such as the laser chip 10, a main body 84 to which the heat spreader 81 and the wiring board 82 are fixed, and a main body 84 are penetrated. A lead pin 85 that is electrically connected to an element provided inside the main body 84, a cap 86 that is connected to the main body 84 and hermetically seals, and is provided on the cap 86 and is emitted from the low reflection film side of the laser chip 10. A glass window 87 through which the transmitted light is transmitted.

  The laser element 80 may be provided with wiring, a thermistor for monitoring the temperature inside the main body, a Peltier element for lowering the temperature, a photodiode for monitoring the amount of light emission, etc. For simplicity, these members are not shown. A plurality of lead pins 85 correspond to the respective elements and the laser chip 10, and each element operates by supplying power to the corresponding lead pin 85. Further, a control signal obtained from the internal temperature and light output is also output via this lead pin, and fed back to a driving device (not shown) of the laser element 80.

  When the laser element 80 has such a configuration, a plurality of elements need to be fixed to the main body, so that there are a plurality of portions to be bonded, and the amount of adhesive used is increased. Moreover, since the internal wiring is covered with vinyl, which is an organic substance, there are many sources of contaminants.

  The cap 86 and the main body 84 are made of metal such as copper or iron, and the connection between the cap 86 and the main body 84 is performed by welding, low-temperature soldering, or the like. However, the HHL package is difficult to connect as compared with the can package shown in the second embodiment, and the yield is poor in the prior art because there are many cases where sealing failure occurs. Also, when connecting using low-temperature solder, the flux that is contained in the low-temperature solder and removes the metal oxide film on the connection surface to make a clean surface contains rosin that is an organic substance. Contaminants were generated.

  However, if the light-absorbing film is provided on the surface of the protective film of the laser chip 10 as in this embodiment, even if organic matter drifts in the interior or the connection is incomplete, contaminants are transferred to the laser chip. Since adhesion and deposition are prevented, it can be driven without problems. Specifically, the yield decreases due to sealing failure due to the failure of the connection between the cap 86 and the main body 84, and the drive current needs to be increased due to the adhesion and deposition of contaminants on the laser chip. Can be prevented from becoming unstable.

  As in the second embodiment, in the case where a photodiode is provided inside the package to receive light from the highly reflective film side of the laser chip, the laser chip configuration may be the same as in the second embodiment. Absent. That is, the reflectance of the high reflection film may be 70% to 80%, and a light absorption film may be formed on the surface of the high reflection film.

  In addition to the laser chip, a hologram laser element used as a light source for an information recording apparatus such as an optical pickup also includes a plurality of elements (optical elements such as a signal detection photodiode and a hologram element) in addition to the laser chip. In such a configuration, a laser chip in which a light absorption film is formed on the surface of the protective film can be provided as in this embodiment. In addition, it is possible to obtain an effect of preventing a decrease in yield due to incomplete hermetic sealing, and a need to increase a driving current or an unstable operation due to contamination and deposition of contaminants on the laser chip. Can do.

<Fourth embodiment>
In the first to third embodiments described above, the embodiment mainly relating to the chip configuration and the package configuration has been shown. However, in the following fourth to thirteenth embodiments, a laser made of a nitride-based semiconductor is used. An example of the configuration of the low reflection film and the light absorption film formed on the end face on the light emission side of the chip will be described. In the following, only the configuration of the low reflection film and the light absorption film will be shown, but the configuration of the chip and the high reflection film and the configuration of the package may be any configuration. Further, the combinations of films shown below are only examples, and it is possible to obtain the effects of the present invention with other combinations.

In the fourth embodiment, the low reflection film formed on the end face on the light emitting side is formed of an aluminum nitride (AlN) film / silicon nitride (SiN) film / aluminum oxide (Al ₂ O ₃ ) film from the end face on the light emitting side. It shall be formed in order. A gold (Au) film is formed as a light absorption film on the Al ₂ O ₃ film that is the uppermost film constituting the low reflection film. The thickness of each film is 20 nm for the AlN film, 300 nm for the SiN film, 80 nm for the Al ₂ O ₃ film, and 4.5 nm for the Au film.

The AlN film formed on the end face on the light emitting side is firmly adhered to the nitride semiconductor constituting the chip and other films constituting the low reflection film. Therefore, by forming this AlN film, it is possible to prevent the low reflection film from being peeled off from the end face, and the yield can be improved. Furthermore, when the end face on the light emitting side and the AlN film are in close contact with each other, it is possible to prevent the end face from undergoing a reaction such as oxidation and deteriorating. Further, since the occurrence of non-radiative recombination on the surface of the end face is suppressed by preventing the end face from deteriorating, the end face melts and breaks due to the heat generated by the rapid increase in non-radiative recombination. damage) is prevented and stable operation can be performed. The AlO _x N _1-x described above has the same characteristics as AlN, and the same effect can be obtained even when a film made of this material is used.

Further, since the SiN film has a small coefficient of thermal expansion, the structure of the protective film can be maintained even if a light absorption film that generates heat is provided. Moreover, since it is excellent also in moisture resistance, it can prevent that an end surface changes in quality with a water | moisture content. For this reason, it is possible to perform a stable operation (in particular, prevention of increase in drive current with drive time when the light output is constant). Silicon oxynitride (SiO _x N _1-x (where 0 <x <1)) has the same characteristics as SiN, and the same effect can be obtained by using a film made of this material. Obtainable. And the structure used in combination with the above-described structure of forming AlO _x N _1-x or AlN on the end face on the light emitting side, that is, SiO _x N _1-x between the light absorption film and AlO _x N _1-x or AlN. Alternatively, a structure sandwiching SiN is preferable because more stable operation can be performed.

Note that a double-layer structure in which SiO _x N _1-x or SiN is formed directly on the end face of the semiconductor and a light absorption film is formed thereon may be used. In addition, an oxide film (eg, aluminum oxide, silicon oxide, titanium oxide, etc.) or a nitride film (eg, aluminum nitride, silicon nitride, titanium nitride, etc.) between the semiconductor and SiO _x N _1-x or SiN. Alternatively, another film such as an oxide film or a nitride film may be formed between SiO _x N _1-x or SiN and the light absorption film. As described above, if the structure is such that SiO _x N _1-x or SiN is sandwiched between the end face of the semiconductor and the outermost light absorption film, moisture resistance, which is a problem in a non-hermetic package, The adhesion of one Si-based substance can be improved at the same time, which is preferable.

  Further, by forming an Au film that is a light absorption film on the surface of the low reflection film, it is possible to prevent contaminants from adhering to and depositing on the low reflection film and the light absorption film. Therefore, it is possible to obtain an effect of preventing the drive current from being increased or the operation becoming unstable as the drive time elapses. Then, by forming the protective film and the light absorption film as described above, it is possible to perform a long-life and stable operation even when the laser element is driven in an air atmosphere.

  Even if the thickness of the Au film as the light absorption film is changed to 1 nm, 2 nm, and 7 nm, the same effect as described above can be obtained.

<Fifth embodiment>
In the fifth embodiment, the material of the low reflection film formed on the end face on the light emitting side is the same as that of the fourth embodiment. That is, it is assumed that the AlN film / SiN film / Al ₂ O ₃ film is formed in this order from the end face on the light emitting side. Then, a platinum (Pt) film is formed as a light absorption film on the Al ₂ O ₃ film which is the uppermost film constituting the low reflection film. The thickness of each film is 6 nm for the AlN film, 100 nm for the SiN film, 200 nm for the Al ₂ O ₃ film, and 4 nm for the Pt film.

  Even if the light absorption film composed of the low reflection film and Pt is configured in this way, the effects of having the low reflection film firmly adhered to the end face and the contaminants are similar to those in the first to fourth embodiments described above. The effect of preventing adhesion and deposition on the low reflection film and the light absorption film can be obtained. The same effect can be obtained even if the AlN film or the SiN film is made thinner than the fourth embodiment as in this embodiment.

  Even if the thickness of the Pt film, which is a light absorption film, is changed to 1 nm, 2 nm, and 8 nm, the same effect as described above can be obtained.

<Sixth embodiment>
In the sixth embodiment, the material of the low reflection film formed on the end face on the light emitting side is the same as in the fourth and fifth embodiments. That is, it is assumed that the AlN film / SiN film / Al ₂ O ₃ film is formed in this order from the end face on the light emitting side. In this embodiment, a titanium (Ti) film is first formed on the Al ₂ O ₃ film that is the uppermost film constituting the low reflection film, and a gold (Au) film is further formed thereon. The light absorption film is a composite film of a Ti film and an Au film. The thickness of each film is 20 nm for the AlN film, 300 nm for the SiN film, 80 nm for the Al ₂ O ₃ film, 1.5 nm for the Ti film, and 2.5 nm for the Au film.

  Even when the light absorption film composed of the low reflection film and the composite film is configured as described above, the effect of firmly attaching the low reflection film to the end face and the pollutant as in the first to fifth embodiments described above. Therefore, it is possible to obtain an effect by preventing adhesion and deposition on the low reflection film and the light absorption film.

  In this embodiment, the light absorption film is composed of a composite film of a Ti film and an Au film. However, the Au film may be changed to a Pt film having the same thickness as the Au film, and in this case, the same effect is obtained. Can be obtained.

<Seventh embodiment>
In the seventh embodiment, the material of the low reflection film formed on the end face on the light emitting side is the same as that in the fourth to sixth embodiments. That is, it is assumed that the AlN film / SiN film / Al ₂ O ₃ film is formed in this order from the end face on the light emitting side. In this embodiment, a molybdenum (Mo) film is formed as a light absorption film on the Al ₂ O ₃ film that is the uppermost film constituting the low reflection film. The thickness of each film is 20 nm for the AlN film, 300 nm for the SiN film, 80 nm for the Al ₂ O ₃ film, and 4.0 nm for the Mo film.

  Even when the light absorption film composed of the low reflection film and the Mo film is configured as described above, the effects of the low reflection film firmly adhered to the end face and the pollutants as in the first to sixth embodiments described above. Therefore, it is possible to obtain an effect by preventing adhesion and deposition on the low reflection film and the light absorption film.

  Even if the thickness of the Mo film, which is a light absorption film, is changed to 1 nm, 2 nm, and 12 nm, the same effect as described above can be obtained.

<Eighth Example>
In the eighth embodiment, the material of the low reflection film formed on the end face on the light emitting side is the same as that in the fourth to seventh embodiments. That is, it is assumed that the AlN film / SiN film / Al ₂ O ₃ film is formed in this order from the end face on the light emitting side. In this embodiment, a molybdenum (Mo) film is first formed on Al ₂ O ₃ which is the uppermost film constituting the low reflection film, and a platinum (Pt) film is further formed thereon. The absorption film is a composite film of Mo film and Pt film. The thickness of each film is 20 nm for the AlN film, 300 nm for the SiN film, 80 nm for the Al ₂ O ₃ film, 1.5 nm for the Mo film, and 2.5 nm for the Au film.

  Even if the light absorption film composed of the low reflection film and the composite film is configured as described above, the effect of the low reflection film firmly adhered to the end face and the contaminants as in the first to seventh embodiments described above. Therefore, it is possible to obtain an effect by preventing adhesion and deposition on the low reflection film and the light absorption film.

  In this embodiment, the light absorption film is composed of a composite film of an Mo film and an Au film. However, the Au film may be changed to a Pt film having the same thickness as the Au film. Can be obtained.

<Ninth embodiment>
In the ninth embodiment, the material of the low reflection film formed on the end face on the light emitting side is the same as that in the fourth to eighth embodiments. That is, it is assumed that the AlN film / SiN film / Al ₂ O ₃ film is formed in this order from the end face on the light emitting side. In this embodiment, an aluminum (Al) film is formed as a light absorption film on Al ₂ O ₃ which is the uppermost film constituting the low reflection film. The thicknesses of the respective films are 20 nm for the AlN film, 300 nm for the SiN film, 80 nm for the Al ₂ O ₃ film, and 4.0 nm for the Al film.

  Even if the low-reflection film and the light-absorbing film made of Al are configured in this way, the effects of the low-reflection film firmly adhered to the end face and the contaminants are the same as in the first to eighth embodiments described above. The effect of preventing adhesion and deposition on the low reflection film and the light absorption film can be obtained.

<Tenth embodiment>
In the tenth embodiment, the material of the low reflection film formed on the end face on the light emitting side is the same as that in the fourth to ninth embodiments. That is, it is assumed that the AlN film / SiN film / Al ₂ O ₃ film is formed in this order from the end face on the light emitting side. In this example, an oxygen deficient aluminum film represented by AlO _x (0 <x <1.5) as a light absorption film on Al ₂ O ₃ which is the uppermost film constituting the low reflection film, That is, an oxygen deficient film of aluminum oxide is used. Here, the composition of AlO _x is shifted from the composition of Al: O = 2: 3, which is a stoichiometric composition, in a direction in which oxygen decreases. The thickness of each film is 20 nm for the AlN film, 300 nm for the SiN film, 80 nm for the Al ₂ O ₃ film, and 60 nm for the AlO _x film.

As described above, Al ₂ O ₃ is almost transparent to the emitted laser light. However, since an oxygen-deficient film such as AlO _x can absorb light well, such a film is used. Then, it can be used as a light absorption film.

As a method for producing the AlO _x film, for example, when an ECR sputtering apparatus is used as in the example shown in the first embodiment, the flow rate of oxygen gas (for example, 5.8 ccm) for forming the Al ₂ O ₃ film ) Is reduced (for example, 4.3 ccm). Other conditions such as the flow rate of argon gas and the power to be supplied are the same as those in the first embodiment, that is, the flow rate of argon gas is 20 ccm, the RF power applied to the Al target is 500 W, and plasma is generated The microwave power for use may be 500 W.

Even if the light absorbing film made of the low reflection film and AlO _x is constructed in this way, the effect of firmly attaching the low reflection film to the end face and the pollutant as in the first to ninth embodiments described above. Therefore, it is possible to obtain an effect by preventing adhesion and deposition on the low reflection film and the light absorption film.

Furthermore, since the AlO _x film used as the light absorption film in this embodiment can control the amount of light absorption by the value of x and the film thickness of the composition, the light absorption amount can be achieved only by the thickness of the metal film or the like. Stricter adjustment can be performed than the light absorption film to be controlled. For example, if it is desired to suppress the optical absorption to the limit, but becomes difficult must choose a film forming method or deposition conditions to form a very thin uniform film in the case of using a metal film, AlO _x film In the case of using a thick film, even if it is a thick film, it can be dealt with by setting the value of x to a value close to 1.5.

  In addition, when manufacturing using a sputtering apparatus, a low reflection film and a light absorption film are formed by setting Al and Si targets and changing the flow rates of argon, oxygen, and nitrogen gas supplied as appropriate. Therefore, film formation can be performed in a continuous process.

Instead of using AlO _x as the light absorption film, an oxygen-deficient silicon oxide film (for example, thickness 8 nm) represented by SiO _x (0 <x <2) may be used. Here, SiO _x has a composition shifted from the stoichiometric composition of Si: O = 1: 2 in the direction of decreasing oxygen. Even if the SiO _x film is used in this way, the same effect as when AlO _x is used can be obtained.

Further, instead of the oxygen-deficient film, a nitrogen-deficient aluminum film represented by AlN _x (0 <x <1) or a nitrogen-deficient state represented by SiN _x (0 <x <1.33...) A silicon nitride film may be used. Here, AlN _x has a composition shifted from the composition of Al: N = 1: 1, which is a stoichiometric composition, in a direction in which nitrogen decreases, and SiN _x has a stoichiometric composition, Si: The composition deviates from the composition of N = 3: 4 in the direction of decreasing nitrogen.

AlN absorbs very little of the emitted light. However, as in the case of the oxygen deficient film shown in the tenth embodiment, the amount of light absorbed can be increased by using the nitrogen deficient film so that it can be used as a light absorbing film. Become. The manufacturing method using the sputtering apparatus is the same as that of the oxygen-deficient film, and can be easily manufactured by making the flow rate of nitrogen gas smaller than the flow rate when forming the AlN film. SiN is deficient in nitrogen but has a small amount of light absorption. Therefore, when SiN _x is used as the light absorption film, it is preferable to make the value of x smaller.

Similarly to the oxygen-deficient film, the amount of light absorption can be controlled by the value of x and the film thickness of the AlN _x or SiN _x nitrogen-deficient film, so that only the thickness of the metal film or the like can be used. Stricter adjustment can be performed than a controllable light absorption film. In either case of producing a light absorbing film, when using a sputtering apparatus, an Al and Si target is set, and the supplied argon, oxygen, and nitrogen gas flow rates are changed as appropriate. Since a low reflection film and a light absorption film can be formed, film formation can be performed in a continuous process.

<Eleventh embodiment>
In the eleventh embodiment, the material of the low reflection film formed on the end face on the light emitting side is the same as that in the fourth to tenth embodiments. That is, it is assumed that the AlN film / SiN film / Al ₂ O ₃ film is formed in this order from the end face on the light emitting side. In this embodiment, a titanium nitride (TiN) film is formed as a light absorption film on the Al ₂ O ₃ film which is the uppermost film constituting the low reflection film. The thickness of each film is 20 nm for the AlN film, 300 nm for the SiN film, 80 nm for the Al ₂ O ₃ film, and 20 nm for the TiN film.

  Sputtering can also be used for the production of the TiN film. In the ECR sputtering apparatus as described above, it is easily produced by introducing nitrogen gas and argon gas and performing sputtering using a Ti target. be able to.

  Even if the light absorption film composed of the low reflection film and TiN is configured as described above, the effects of the low reflection film firmly adhered to the end face and the contaminants are the same as in the first to tenth embodiments described above. The effect of preventing adhesion and deposition on the low reflection film and the light absorption film can be obtained.

The TiN film and the above-described AlN _x film and SiN _x film are not limited to other metals (for example, zirconium (Zr), yttrium (Y), niobium (Nb), hafnium (Hf), tantalum (Ta), tungsten). Even the nitride film of (W)) can absorb the emitted light, and may be used as a light absorption film. Further, these films may be used as nitrogen deficient films.

<Twelfth embodiment>
In the twelfth embodiment, the material of the low reflection film formed on the end face on the light emitting side is the same as that in the fourth to eleventh embodiments. That is, it is assumed that the AlN film / SiN film / Al ₂ O ₃ film is formed in this order from the end face on the light emitting side. In this embodiment, a palladium oxide film is used as a light absorption film on Al ₂ O ₃ which is the uppermost film constituting the low reflection film. The thickness of each film is 20 nm for the AlN film, 300 nm for the SiN film, 80 nm for the Al ₂ O ₃ film, and 3 nm for the palladium oxide film.

  As a method for forming the palladium oxide film, for example, a method of forming a Pd metal film and oxidizing it with oxygen plasma in a plasma generator can be used. In addition to using a palladium oxide target, it can be formed by vapor deposition or sputtering. Further, a film may be formed while introducing oxygen, or oxidation may be performed using oxygen plasma or the like after the film is formed.

  Further, it is preferable that the thickness t of palladium oxide is in the range of 0 nm <t ≦ 100 nm. If it is 100 nm or more, the ratio of light absorption increases, and the light extraction efficiency decreases. A more preferable condition is 0 nm <t ≦ 50 nm, and a more preferable condition is 0 nm <t ≦ 10 nm. Moreover, the effect can be acquired if the light absorption film adheres even a little.

  In the above example, palladium oxide is used as the light absorption film, but metal oxides such as rhodium (Rh), iridium (Ir), osmium (Os), and ruthenium (Ru) may be used. I do not care. Also, a combination of a plurality of these metal oxides may be used.

<Thirteenth embodiment>
In the thirteenth embodiment, it is assumed that the low reflection film is formed in the order of the AlO _x N _1-x film / SiN film from the end face on the light emission side. A palladium (Pd) film is used as a light absorption film formed on the surface of the SiN film, which is the uppermost film constituting the low reflection film. The thicknesses of the respective films are 20 nm for the AlO _x N _1-x film, 160 nm for the SiN film, and 5 nm for the Pd film. This laser chip is shown in FIG. FIG. 11 is a schematic perspective view of a laser chip in the thirteenth embodiment, which schematically shows an enlarged side where a light absorption film is formed.

  As shown in FIG. 11, in the laser chip 110 in this embodiment, a part of the light absorption film 112 formed on the surface of the low reflection film 111 is aggregated (dotted). As a method of forming dots, for example, there is a method of driving a laser element. When the laser element is driven to cause laser oscillation, part of the emitted laser light is absorbed by palladium forming the light absorption film 112, and part of the light absorption film 112 generates heat. The light absorption film 112 can be formed into dots by the heat generated at this time, and a laser chip 110 in which a part of the light absorption film 112 is formed as shown in FIG. 11 can be obtained.

  In addition, dot formation occurs mainly in a region through which laser light passes. In such a region, since the light absorption film 112 is sufficiently heated by the laser light, dot formation is promoted, and the light absorption film dots 112b in which the light absorption film 112 becomes granular are formed. Further, in the region where the light absorption film dots 112b are formed, palladium forming the light absorption film 112 aggregates when the light absorption film dots 112b are formed, so that the light absorption film 112 becomes discontinuous (with a thickness of 0). Part will occur). In such a discontinuous region 112a, there is a portion where the SiN film which is the uppermost film of the low reflection film 111 is exposed. On the other hand, in the continuous region 112c other than the discontinuous region 112a, the light absorption film 112 becomes a continuous film and the low reflection film 111 does not appear.

  The dot formation of the light absorption film 112 can be caused by, for example, continuous oscillation at an optical output of 30 mW and 25 ° C. for about 2 hours. The result of performing an operation test by continuously driving the laser chip 110 that has been dot-formed in this manner at 20 mW and 25 ° C. for about 1000 hours will be described with reference to FIG. FIG. 12 is a photomicrograph showing a cross section of the laser chip in the thirteenth embodiment of the present invention, which is taken using a transmission electron microscope (TEM). Moreover, the cross section equivalent to the AA cross section of the laser chip 110 in FIG. 11 is shown.

As shown in FIG. 12, an AlO _x N _1-x film 111a having a thickness of 20 nm is provided on the end face on the light emitting side of the nitride semiconductor 113, and a SiN film 111b having a thickness of 160 nm is further provided on the upper surface thereof. A light absorption film 112 made of palladium having a thickness of 5 nm is provided on the upper surface of the SiN film 111b. The light absorption film 112 includes a discontinuous region 112a including a light absorption film dot 112b in the region, and a continuous region 112c. The size of the light absorption film dot 112b depends on the thickness of the light absorption film 112 to be formed, and is about 0.5 nm to about 50 nm.

  As shown in FIG. 12, even when the laser chip 110 in which a part of the light absorption film 112 is formed into a dot is driven, contaminants are prevented from adhering and depositing on the end face of the laser chip 110. That is, even if the light absorption film 112 is not a continuous layer, but is granular and interrupted, it is possible to prevent the contaminants from adhering to and accumulating on the end face.

  Further, when the light absorption film dots 112b are formed as in this embodiment, the metal (palladium in this embodiment) forming the light absorption film 112 around the light absorption film dots 112b is eliminated (the thickness is 0). Therefore, it becomes possible to emit light efficiently by reducing the amount of light absorption. That is, the slope efficiency when the laser element is driven can be improved, and the drive current can be reduced.

  Further, when the laser light is emitted as in the present example to perform dot formation, the portion through which the light passes can be reliably and easily formed into dots.

  In this embodiment, as a dot forming method, a method of aggregating by emitting laser light has been described. However, a method of heating the entire laser chip 110 to form dots may be used. In such a case, unlike the configuration shown in FIGS. 11 and 12, the discontinuous region 112a of the light absorption film 112 extends over the whole. However, even if it extends to the whole as described above, it is possible to obtain the effect of preventing the contaminants from adhering and depositing as in the above-described embodiments.

  Further, dot formation may be caused by applying some energy such as light or heat to the light absorption film 112 from the outside. With this configuration, the discontinuous region 111a can be formed at an arbitrary position. Further, it may be formed into dots when the light absorption film 112 is formed. That is, the film may be formed while aggregating. In addition, at least a part of the light absorption film 112, in particular, at least a part of a region through which the emitted laser light passes is formed into a dot and becomes discontinuous, and any method is used for dot formation. It does n’t matter.

  Moreover, the effect of this example can be obtained even if the light absorption film 112 is configured not to include the discontinuous region 112a. For example, the light absorption film 112 may include a continuous layer, and the above-described light absorption film dots 112b may be formed on the surface of the layer. Even in such a configuration, the light absorption is reduced if the thickness of the continuous layers is sufficiently thin. Therefore, the effect of reducing the drive current is the same as in the case of forming the discontinuous region 112a. Can be obtained. Further, even if the thickness is sufficiently thin, grains made of the material of the light absorption film 112 are formed on the surface, so that adhesion and deposition of contaminants can be prevented by the grains.

  Further, by selecting the thickness of the light absorption film 112, the type of material to be used, the type of the underlayer, and the like, the size of dot formation can be controlled. In this embodiment, palladium is used as the dot metal, but gold (Au), platinum (Pt), rhodium (Rh), iridium (Ir), osmium (Os), ruthenium (Ru), or the like is used. It doesn't matter.

<Modification>
In the first to thirteenth embodiments described above, an example in which the low reflection film is formed of two or three kinds of films has been shown, but it may be made of one kind of film. Further, as the protective film, an oxide containing at least one element selected from Al, Si, Hf, Ti, Nb, Ta, W and Y, a nitride of Al or Si, and an oxynitride of Al or Si are used. It may be included.

Further, in the above-described fourth to thirteenth embodiments, only the configuration on the low reflection film side has been described, but in the case of a configuration in which a part of light is emitted also from the high reflection film side, each light absorption film is You may comprise on the surface of a highly reflective film. With this configuration, it is possible to prevent contaminants from adhering and depositing on the highly reflective film side. Further, a film that enhances adhesion, such as an AlN film or an AlO _x N _1-x film, may be directly formed on the end face where the high reflection film is formed as a part of the high reflection film. Further, the high reflection film may be provided with a SiN or SiO _x N _1-x film.

In addition, since the light absorption film is provided and the protective film is made of SiN or SiO _x N _1-x , the increase in driving current can be further reduced. It is preferable to provide the protective film with a film. In particular, when an SiO _x N _1-x film is used, an effect of suppressing an increase in driving current can be obtained by providing the SiO _x N _1-x film having a thickness of 20 nm or more. Therefore, it is preferable that the SiO _x N _1-x film is provided with a thickness of 20 nm or more, more preferably 80 nm or more.

  The thickness t of the light absorbing film is preferably in the range of 0 nm <t ≦ 100 nm. If it is 100 nm or more, the ratio of light absorption increases, and the light extraction efficiency decreases. A more preferable condition is 0 nm <t ≦ 50 nm, and a more preferable condition is 0 nm <t ≦ 10 nm. Moreover, the effect can be acquired if the light absorption film adheres even a little.

  In addition, when Au, Pt, Rh, Ir, Pd, Os, Ru, or the like is used as a material used for the light absorption film, the adhesion coefficient of a Si-based substance, which is one of the contaminants, is reduced and it is difficult to adhere. Therefore, it is preferable. In addition, when the light absorption film is formed of two or more kinds of films as in the sixth embodiment and the eighth embodiment described above, it is possible to remove contaminants by using a film made of these metals as the outermost film. This is preferable because it has an effect of suppressing adhesion and deposition.

  The light absorbing film may be made of two or more kinds of alloys. The light absorption film may be a composite film in which several kinds of films are combined, such as a metal film and a nitride film, a nitride film and an oxygen deficient film, or the like.

  The present invention relates to a semiconductor light emitting device and a method for manufacturing the semiconductor light emitting device, and in particular, a silicon oxide or the like in a light emitting portion represented by a laser device that emits light of a short wavelength using a nitride semiconductor. The present invention relates to a semiconductor light emitting device having a light emission wavelength at which a contaminant is attached and deposited and a method for manufacturing the same.

These are typical side views of the laser chip in the embodiment of the present invention. These are the graphs which show the result of the operation test of the laser element in the execution form of this invention. FIG. 3 is a schematic side view of a laser chip provided with an AlN film. These are the graphs which show the result of the operation test of the laser element provided with the laser chip shown in FIG. These are a schematic perspective view and side view of the laser chip in the first embodiment of the present invention. These are the typical perspective views of the laser element in 1st Example of this invention. These are the typical perspective views of the laser element in the 2nd example of the present invention. These are the typical perspective views of the laser element in the 3rd example of the present invention. These are the typical side views of the conventional laser chip. These are the graphs which show the result of the operation test of the conventional laser element. These are the typical perspective views of the laser chip in the 13th Example of this invention. These are the microscope pictures which showed the cross section of the laser chip in 13th Example of this invention.

Explanation of symbols

1, 10 Laser chip 2 Active layer 3 Low reflection film 3a AlO _x N _1-x film 3b SiN film 3c Al ₂ O ₃
4 High Reflective Film 4a AlO _x N _1-x Film 4b SiN Film 4c SiO ₂ Film 4d TiO ₂ Film 4e SiO ₂ Film 5 Light Absorbing Film 11 Substrate 12 Buffer Layer 13 N-type Cladding Layer 14 n-Type Guide Layer 15 Multiple Quantum Well Active layer 16 Protective layer 17 Current blocking layer 18 p-type cladding layer 19 p-type contact layer 20 ridge stripe 21 insulating film 22 p-electrode 23 n-electrode 110 laser chip 111 low reflection film 111a AlO _x N _1-x film 111b SiN film 112 Light absorption film 112a Discontinuous region 112b Light absorption film dot 112c Continuous region 113 Nitride semiconductor

Claims (27)

In a light emitting device including a chip that emits light,
A light-emitting element comprising a light absorption film that absorbs part of emitted light on an outermost surface on an end face from which light of the chip is emitted.   The chip is formed on an end face from which light of the chip is emitted and includes a protective film for protecting the end face, and the light absorption film is formed on a surface of the protective film. 2. The light emitting device according to 1.   The said protective film is provided with the oxide film which consists of an oxide containing at least 1 element chosen from the group of aluminum, titanium, yttrium, silicon, niobium, hafnium, and tantalum. Light emitting element.   The said protective film is provided with the film | membrane containing at least 1 compound of the nitride of aluminum, silicon nitride, aluminum oxynitride, and silicon oxynitride, The Claim 2 or Claim 3 characterized by the above-mentioned. Light emitting element.   The light-emitting element according to claim 1, wherein the light absorption film includes a metal film made of metal.   The light emitting device according to claim 5, wherein the metal film includes at least one element selected from the group consisting of gold, platinum, rhodium, iridium, osmium, ruthenium and palladium. The light absorbing film is
An oxygen deficient film comprising an oxide containing at least one element selected from the group consisting of aluminum, titanium, zirconium, yttrium, silicon, niobium, hafnium, tungsten, and tantalum, and having less oxygen than the stoichiometric composition The
The light emitting device according to claim 1, further comprising:   The light absorbing film includes a nitride film made of a nitride containing at least one element selected from the group consisting of aluminum, titanium, zirconium, yttrium, silicon, niobium, hafnium, tungsten, and tantalum. The light emitting device according to claim 1.   The light emitting device according to claim 1, wherein the chip is a laser chip that emits laser light.   The light emitting device according to claim 9, wherein the light emitting device is configured not to hermetically seal the chip.   The light emitting device according to claim 10, wherein the light emitting device has a structure in which the chip is provided in a frame package.   The light emitting device according to claim 9, wherein the light emitting device is provided with the chip being hermetically sealed in an HHL package.   The light emitting device according to claim 9 or 12, wherein the light emitting device is provided with the chip hermetically sealed together with an adhesive containing an organic substance.   The light-emitting element according to claim 1, wherein the chip includes a layer made of a nitride-based semiconductor. In a method for manufacturing a light emitting element including a laser chip that emits laser light,
A first step of forming a protective film that protects the end face on a portion that becomes an end face that emits laser light of the laser chip;
After the first step, a second step of forming a light absorbing film that absorbs part of the laser light emitted from the laser chip on the surface of the protective film;
A method for manufacturing a light-emitting element, comprising:   The method according to claim 15, further comprising a third step of mounting the laser chip without hermetically sealing. The light absorption film is made of metal, and at least a part of the light absorption film is a non-uniform region where the thickness in the region is non-uniform,
5. The light emitting device according to claim 1, wherein at least a part of the light emitted from the chip is emitted through at least a part of the non-uniform region.   The light emitting device according to claim 17, wherein the non-uniform region of the light absorption film is a discontinuous region where the light absorption film is discontinuous.   The light emitting device according to claim 18, wherein the discontinuous region of the light absorption film is a region including grains made of the metal forming the light absorption film. The non-uniform region of the light absorbing film is
The light-emitting element according to claim 17, wherein the light-emitting element is a region including a layer in which the metal constituting the light absorption film is continuous, and a grain made of the metal formed on a surface of the layer.   21. The light-emitting element according to claim 17, wherein the metal includes at least one element selected from the group consisting of gold, platinum, rhodium, iridium, osmium, ruthenium and palladium. .   The light-emitting element according to claim 1, wherein the light absorption film is made of palladium oxide.   The light emitting device according to any one of claims 17 to 22, wherein the light emitting device is configured not to hermetically seal the chip.   The light emitting device according to claim 23, wherein the light emitting device has a configuration in which the chip is provided in a frame package. In a light emitting device including a chip that emits light,
A light emitting element comprising a metal film made of metal on an outermost surface on an end face from which light of the chip is emitted.   24. The light emitting device according to claim 23, wherein at least a part of the metal film is a region in which the metal forming the metal film is granular.   The light emitting device according to claim 23, wherein the metal film is a continuous layer.