JP2008066349A - Optical semiconductor device and method and apparatus of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the performance of a semiconductor device by reducing uncoupled hands existing on the surface of a substrate such as a light emitting face or the like in the optical semiconductor device. <P>SOLUTION: The optical semiconductor device 10 wherein a light emitting face or a light reflecting face as a typical cleavage face is formed is immersed in a solution containing a cyano compound, sprayed therewith, or exposed to its steam, so that uncoupled hands existing on the surface of the light emitting face or the like are terminated by bondage to a cyano group (-CN). Thus, degradation owing to the oxidization of the active light emitting face or the light reflecting face or the expansion of a non-light emitting part adjacent therewith is prevented. As a result, the optical semiconductor device superior in reliability can be obtained. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to an optical semiconductor device that uses an optical mirror surface such as a semiconductor laser, a manufacturing method thereof, and a manufacturing apparatus thereof.

  A semiconductor laser is a solid optical semiconductor device that emits light by stimulated emission by supplying forward current to a pn junction and recombination of injected electrons and holes. This device, also called a laser diode (LD), is an optical device for inputting (writing) data to a recording medium of an information device such as a compact disc (CD) device or DVD device, or for outputting (reading) the data. Used as a light source for the means. In addition, this apparatus is widely used as an optical excitation light source for a solid-state laser, a signal source used for optical fiber communication, or an excitation light source for a fiber amplifier, for example.

  This type of semiconductor laser has a double hetero structure in which both sides of the active layer where the carriers recombine are sandwiched between confinement layers (called cladding layers) because the light emission efficiency is improved by simultaneously confining the carriers and confining the light. Is adopted. Laser oscillation starts when the supply current is increased and reaches a certain current value (referred to as a threshold current). As the material, for example, a semiconductor such as a III-V group compound is used. Specifically, the InGaAsP system is used for oscillation wavelengths of 1250 to 1700 nm, the GaN system and AlGaInP system are used for oscillation wavelengths of 400 nm and 600 nm bands, and the oscillation wavelength of 770 nm to 860 nm band, respectively. AlGaAs and InGaAs materials are used.

  Light propagates and is emitted along an optical waveguide formed by an active layer sandwiched between clad layers on both sides (a pair) of the heterostructure. Here, the end surface of the optical waveguide needs to be a mirror surface having a reflection function so as to promote confinement and amplification of light generated inside. Therefore, in order to obtain the mirror surface, an end face obtained by cleaving a crystal, that is, a cleaved surface is generally used. On the surface of the substrate that forms the light emitting surface or light reflecting surface typified by this cleaved surface, there are dangling bonds of atoms, oxygen, hydrogen, or other metals such as dangling bonds. Elements are bonded. These bonds with dangling bonds and impurities such as metals generate surface levels (including interface levels generated at the interface with the passivation film, hereinafter referred to as surface levels). Then, due to such surface states, light absorption and leakage current increase, and heat is generated. This heat generation causes a positive feedback phenomenon in which the band gap of the active layer is narrowed and the absorption and the like are further increased, resulting in problems such as saturation of light output and reduction of light output.

  Several solutions have been proposed for such technical problems. For example, by changing the crystal composition of the end face of the optical waveguide, a technique for expanding the band gap of the semiconductor rather than the light emission energy inside the semiconductor crystal has been proposed as a means for preventing laser light absorption at the end face (for example, , See Patent Document 1). There is also a technique for protecting the end face by forming a dielectric coating film for controlling the reflectance (a low-reflection (antireflection) film on the front side and a high-reflection film on the rear side) at the end portion of the optical waveguide ( For example, see Patent Document 2). However, the formation of the protective film sometimes deteriorates the performance of the reflective film because impurities enter the film over time even during or after the formation of the film. Therefore, it is difficult to make full use of the effect.

  None of the above-described techniques does not reduce or eliminate the bond itself with an unbonded hand or an impurity such as a metal present on the substrate surface of the light emitting surface or the light reflecting surface typified by a cleavage plane. In other words, it can be said that conventionally, the problem such as the unbonded hand is not directly solved but the performance is improved by using another solution means.

  By the way, the above-mentioned problem similarly occurs for the surface emitting laser element. Specifically, when a semiconductor multilayer film reflecting mirror in which compound semiconductors of different compositions are alternately stacked is used as a light reflecting mirror, an interface state is formed on the surface of the substrate that becomes the light emitting surface or the light reflecting surface. This is because heat is generated due to absorption of laser light.

  Moreover, the above-described problem is particularly serious for compound semiconductors. This is because when the base material is silicon, so-called hydrogen annealing treatment may be effective in order to reduce surface states and the like, but this hydrogen annealing treatment cannot be applied to compound semiconductors. Specifically, when hydrogen annealing treatment is performed on an optical semiconductor device made of a compound semiconductor, hydrogen enters the inside of the crystal. For example, the hydrogen is activated by zinc (Zn) or magnesium (Mg) added to the active layer. The function of the conductive layer may be lowered by inactivating the activating dopant. Therefore, this hydrogen annealing process cannot be applied to compound semiconductors.

On the other hand, one of the inventors of the present invention has proposed a technique for reducing the interface state density of the insulating film-semiconductor interface by exposing cyano ions mainly to a silicon device having a MIS structure (for example, And Patent Document 3). However, no process technology has been proposed that focuses on the particularity of the light emitting surface or light reflecting surface of the optical semiconductor device described below.
JP-A-57-149787 JP-A-5-37009 Japanese Patent Laid-Open No. 10-74753 JP 2001-15772 A JP 2001-189484 A JP 2004-75490 A JP 2004-342723 A JP 2005-33038 A JP 2005-39198 A

  As described above, in the manufacturing process of the optical semiconductor device, it can be said that the occurrence of bonds with impurities such as unbonded hands or metals on the surface of the base material is inevitable. A means to improve is strongly desired.

  The present invention solves such a technical problem and contributes to the improvement of the stability and reliability of the optical semiconductor device, that is, the improvement of the light output and the suppression of the deterioration. First, the inventors have proposed that various techniques related to the light emission surface or the light reflection surface are not intended to directly reduce a large number of interface states generated on the substrate surface. We paid attention to the fact that it was developed on the premise of existence. Specifically, technologies to deal with the heat generated by the absorption of laser light due to the presence of the interface states and technologies to alleviate the narrowing of the band gap due to heat or reduce the effect of the narrowing have been developed so far. It has been done. Accordingly, if the inventors can reduce the interface state at or near the substrate surface serving as the light emission surface or the light reflection surface, which is the fundamental cause, the technology developed so far will be used. We thought that the performance improvement of the optical semiconductor device could be achieved with almost no dependence. The present invention was created based on such a viewpoint.

  In one optical semiconductor device of the present invention, the surface of the base material serving as a light emitting surface or a light reflecting surface is mainly terminated by bonding of cyano groups.

  Thereby, deterioration with time of the optical semiconductor device is suppressed, and the reliability or stability is improved. In addition, the light output is improved by appropriately selecting the device structure. Specifically, in the conventional device manufacturing process, there are bonds with many unbonded hands and impurities such as metals on the surface of the base material which becomes the light emitting surface or the light reflecting surface or in the vicinity thereof. These are terminated by a cyano group or are replaced by a cyano group, whereby deterioration is suppressed. Note that “mainly” means that not all the bonds with dangling bonds or impurities are terminated by the bond of the cyano group. This meaning is not particularly limited by numerical values. In addition, the termination by bonding of this cyano group (—CN) is particularly the case where the light emission surface or the light reflection surface is a crystal cleavage surface, a surface formed by etching, or a general semiconductor. The effect is increased when the surface is a special surface such as a semiconductor nanoparticle (for example, nano-sized silicon) that is greatly influenced by the presence of dangling bonds as compared with the device.

  Further, in one method of manufacturing an optical semiconductor device according to the present invention, the substrate surface serving as a light emitting surface or a light reflecting surface is immersed in a solution containing a cyanide compound, sprayed with the solution, or vaporized from the solution. It has a process to be exposed.

  Thereby, the region bonded to the dangling bonds or impurities such as metal on the surface of the base material serving as the light emitting surface or the light reflecting surface is terminated by the bond of the cyano group (—CN). As a result, deterioration over time of the optical semiconductor device is suppressed, and an improvement in reliability or stability is achieved. In addition, the light output is improved by appropriately selecting the device structure. If the spray treatment is employed, the total amount of solution used can be reduced regardless of the temperature of the solution used. In addition, for the treatment using steam, it is possible to reduce the amount of the solution used as compared with the immersion in the solution.

  Also, in one optical semiconductor device manufacturing apparatus according to the present invention, the substrate surface serving as the light emitting surface or the light reflecting surface is immersed in a solution containing a cyanide compound, sprayed with the solution, or vapor of the solution. Has means to be exposed.

  By this apparatus, the region bonded to the dangling bonds or impurities such as metal on the base material surface that becomes the light emitting surface or the light reflecting surface of the optical semiconductor device is terminated by bonding of the cyano group. As a result, the manufactured optical semiconductor device is less likely to deteriorate with time, and the reliability or stability is improved. In addition, the light output is improved by appropriately selecting the device structure.

  According to the optical semiconductor device and the method of manufacturing an optical semiconductor device of the present invention, deterioration with time is suppressed, and reliability or stability is improved. In addition, the light output is improved by appropriately selecting the device structure. In addition, according to the optical semiconductor device manufacturing apparatus of the present invention, a dangling bond on the surface of the base material serving as a light emitting surface or a light reflecting surface is present, or a cyano group is bonded to a region bonded to an impurity such as a metal. Termination by group bonding is possible. As a result, a high-performance optical semiconductor device as described above can be manufactured.

Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this description, common parts are denoted by common reference symbols throughout the drawings.
<First Embodiment>
FIG. 1 is a schematic configuration diagram of the optical semiconductor device of the present embodiment. A structure in which an n-type confinement layer (cladding layer) 2, an active layer 3 and a p-type confinement layer (cladding layer) 4 are sequentially disposed on an n-type substrate 1, and the active layer 3 is sandwiched between the clad layers 2 and 4. have. A p-type cap layer 5 shaped in a stripe shape and an insulating film 6 covering the p-type clad layer 4 and the p-type cap layer 5 are formed on the p-type clad layer 4. Further, a first electrode (anode) 7 is formed on the insulating layer 6, and a second electrode (cathode) 8 is formed on the bottom surface of the n-type substrate 1. In the optical semiconductor device 10 of this embodiment, by applying a voltage between the electrodes 7 and 8 and supplying a current, the light generated in the active layer 3 propagates along the active layer between the cladding layers, Laser light is emitted in the direction of the arrow in FIG. 1, with one (front surface) end face on which the antireflective coating film 9 (shown as a broken line and transparent in FIG. 1) is formed as a light exit surface. At this time, since the light reflecting film composed of the highly reflective coating film is formed on the other end face (rear surface, which cannot be seen due to the blind spot in FIG. 1), most of the light is reflected on the active layer. It will return to 3. As a result, the laser light is amplified.

  Next, a method for manufacturing the optical semiconductor device of this embodiment will be described.

  This embodiment is a semiconductor laser having a wavelength (λ) of 780 nm. In this embodiment, an active layer having a quantum well structure in which an n-type AlGaAs crystal cladding layer and a GaAs well layer are sandwiched by AlGaAs barrier layers on an n-type GaAs substrate (wafer) having a crystal plane orientation <100>. , A p-type AlGaAs crystal cladding layer, and a p-type GaAs cap layer are sequentially stacked by metal organic vapor deposition (MOCVD) method or molecular beam epitaxy (MBE) epitaxial growth. Is done. At this time, as the dopant, zinc (Zn) is used for the p-type, and silicon (Si) is used for the n-type. A part of the p-type GaAs cap layer and the p-type AlGaAs crystal cladding layer is shaped into a stripe shape, and a silicon nitride or silicon oxide insulating film is formed on both sides thereof to constitute a current injection stripe region. As for the electrode, the anode side (first electrode) 7 is composed of a double layer metal of TiPtAu (contact side) / Au on the striped p-type GaAs layer and the insulating film, and the cathode side (second electrode) 8 is The entire bottom surface of the substrate is made of AuGeNi (contact side) / Au double-layer metal. Both electrodes 7 and 8 are formed by a metal vapor deposition method.

  Next, a method for separating an optical semiconductor device will be described. First, a structure in which the above-described various layers are simply laminated is divided into rods by a scribing method or a cleavage method so that an end surface perpendicular to the stripe direction becomes a cleavage surface. The lengths at this time are approximately 300 to 2500 μm (this length becomes the element length or the laser cavity length). Subsequently, a low-reflection and high-reflection coating film is formed on the cleavage plane that becomes the light emitting surface and the light reflecting surface. Thereafter, the rod-shaped structure is cut into chips by cutting the current injection stripe so that it is located at the center. This is one optical semiconductor device 10 shown in FIG. Here, it is divided so that the element width is approximately 200 to 300 μm.

  In the present embodiment, the individually divided chips are immersed in a solution containing a cyanide compound. FIG. 2 is an explanatory diagram of the optical semiconductor device manufacturing apparatus of the present embodiment. Using the optical semiconductor device manufacturing apparatus 200 as shown in the figure, the optical semiconductor device 10 described above is immersed in a solution 22 containing a cyanide compound. Specifically, the optical semiconductor device 10 held by a known holding tool (not shown) for convenience is immersed in the solution 22 filled in the treatment tank 24. Here, the solution containing the cyanide compound is prepared by dissolving 0.01 mol of hydrogen cyanide (HCN) in pure water, and is preferably adjusted to pH 7 or more and 10 or less. The temperature of the solution 22 is adjusted to 20 ° C. to 30 ° C. by an insertion type temperature controller 26. The effect of the present invention is sufficiently exhibited even at a low temperature of 60 ° C. or lower.

Here, in the solvent, for example, non-metal cyanide such as hydrogen cyanide (HCN), dicyan ((CN) ₂ ), ammonium cyanide (NH ₄ CN), or potassium cyanide (KCN), sodium cyanide (NaCN), cyanide. The same effect as that of the present invention can be obtained even with a solution containing one metal cyanide compound such as rubidium iodide (RbCN) or cesium cyanide (CsCN) as a solute.

  As the medium, pure water capable of dissolving the above-mentioned solute or a solution mainly composed of hydrophilic alcohol is used. For example, alcohols such as methanol (methyl alcohol), ethanol (ethyl alcohol) and propanol (propyl alcohol, particularly isopropyl alcohol) are suitable. In addition to these alcohols, ketones such as acetone, nitriles such as acetonitrile, aromatic hydrocarbons such as benzene, toluene and xylene, ethers such as carbon tetrachloride, tetrahydrofuran and dioxane, hexane and pentane, etc. Aliphatic alkanes, or a mixture thereof may be used.

  Note that etching of the substrate is prevented by using hydrophilic alcohol as the medium. When water is added to the medium, water molecules act as a solvate for cyanide or cyanide ions in the solution and suppress the activity of the cyanide or cyanide ions.

Further, by using a hydrophilic alcohol such as methanol as a medium, potassium ions (K ⁺ ) are inactive (CH ₃ OK) even if the solute is a metal cyanide such as potassium cyanide (KCN). Is incorporated into the molecule as Therefore, since this potassium is removed together with the cyanide solution, the possibility of metal contamination on the optical semiconductor device is low.

  Further, instead of performing the dipping step after forming the chip to the final stage as in this embodiment, even if the step of dipping in the solution containing the cyanide compound immediately after being divided into the above-described rod shape is adopted, The effect is not impaired. At this stage of the rod-like structure, a plurality of chips can be immersed in the solution at one time. Therefore, it can be said that it is more advantageous to adopt this method from the viewpoint of process efficiency.

  Next, the rinsing step and the waste liquid treatment after the treatment with the solution containing the cyanide compound according to the present embodiment will be described. The effect of the present invention is further exhibited by performing the rinse treatment after the treatment with the solution containing the cyanide compound.

  This rinsing step is performed in order to completely remove the cyanide-containing solution from the light emitting surface or light reflecting surface of the optical semiconductor device. The optical semiconductor device 10 taken out from the solution containing the cyanide compound is washed away using only a solvent (for example, alcohols such as methanol). Since the amount of the solution remaining on the substrate surface, such as light emission, is small, it is easily cleaned by spraying the solvent as a cleaning liquid. This rinsing step may be performed in a plurality of stages using the cleaning liquid. Thereafter, if necessary, the optical semiconductor device 10 may be dried to vaporize the cleaning liquid adhering to the surface.

  Here, the bonding force when the dangling bonds existing on the substrate surface of the light emitting surface or the light reflecting surface are terminated by the bond of the cyano group (-CN) is very strong, For example, it is stable even at a high temperature of 800 ° C. Therefore, it is very unlikely that the bond due to the cyano group is released even after the rinsing step described above.

  On the other hand, in the solvent used to remove the cyanide-containing solution from the substrate surface such as the light exit surface, even if diluted, the cyanide compound, cyano group, or cyanide ion (hereinafter, for convenience) , Referred to as a cyan (CN) component) may remain. Therefore, it is environmentally preferable to decompose and remove the above-mentioned cyan component remaining in the rinse waste liquid by treating the solvent (so-called rinse waste liquid) after the cleaning treatment in ozone or ozone combined with ultraviolet light irradiation. As a result, no cyan component remains in the rinse waste liquid.

After the rinsing step, the light emitting surface and the light reflecting surface in the optical waveguide of the optical semiconductor device are covered with a thin dielectric film for the purpose of controlling the reflectance. In this embodiment, an alumina (Al ₂ O ₃ ) film as a non-reflective coating film 9 (reflectance 3 to 10%) is formed on the light emitting surface side with a film thickness (about ¼ of the oscillation wavelength (λ) ( About 100 nm). On the light reflecting surface side, a multilayer film (Al ₂ O ₃ / a-Si / Al ₂ O ₃ / a-Si) of alumina / amorphous silicon (a-Si) with a high reflection film (reflectance of about 95%) is provided. ) With a thickness of about λ / 4 (100 nm / 60 nm / 100 nm / 60 nm). Note that the non-reflective coating film and the reflective film substantially serve as a passivation film for the light emitting surface or the light reflecting surface. This is because the presence of these films prevents the light exit surface or the like from coming into direct contact with the outside air, thereby preventing the generation of new surface levels due to moisture or oxygen in the outside air.

<Second Embodiment>
Another embodiment of the present invention is a red semiconductor laser having a wavelength (λ) of 660 nm and an output of about 300 mW. This laser is used for DVD reproduction and recording applications, for example. Although the composition of each layer varies, it is structurally almost the same as the optical semiconductor device shown in FIG. Specifically, an n-type AlGaInP crystal cladding layer, a GaAs / AlGaInP active layer, a p-type AlGaInP crystal cladding layer, and a p-type GaAs cap layer are sequentially formed on an n-type GaAs substrate (wafer). The layers are stacked by phase growth (MOCVD) or molecular beam epitaxy (MBE) epitaxial growth. At this time, as the dopant, zinc (Zn) or magnesium (Mg) is used for the p-type, and silicon (Si) is used for the n-type. Part of the p-type GaAs cap layer and the cladding layer of the p-type AlGaInP crystal is shaped into a stripe shape, and a silicon nitride or silicon oxide insulating film is formed on both sides thereof to constitute a current injection stripe region. The active layer employs a quantum well structure in which a GaAs well layer is sandwiched between AlGaInP confinement layers.

  This embodiment is different from the first embodiment in that a semiconductor substrate (wafer) on which a light emitting surface or a light reflecting surface of an optical semiconductor device is formed is immersed in a solution containing a cyanide compound. That is, in this embodiment, since a dry etching process is used when the light emission surface or the like is formed, even if the light emission surface or the like is formed, it is not completely divided into individual chips, and the wafer state It will be immersed in the state. Here, as dry etching conditions, for example, an electron cyclotron resonance (ECR) etching method in which argon ions are irradiated in a chlorine atmosphere is effective. Note that the optical semiconductor device manufacturing apparatus shown in FIG. 2 is applicable to this embodiment as long as the individually divided chips in the first embodiment are replaced with wafers. Therefore, the specific conditions for the dipping process are the same as those in the first embodiment, and will be omitted.

  The optical semiconductor device according to the present embodiment is also different from the first embodiment in that a passivation film that covers the light emitting surface and the light reflecting surface in a wafer state is formed after being immersed in a solution containing a cyanide compound. Different. However, the dangling bonds existing at the etching surface formed by the above-described dry etching or at a depth in the vicinity of the surface are terminated by a cyano group. Therefore, heat generation on the light emitting surface or the like, which is a cause of deterioration of the optical semiconductor device, is suppressed, and reliability or stability is improved as compared with the conventional optical semiconductor device.

<Third Embodiment>
Another embodiment of the present invention is a blue-violet semiconductor laser having a wavelength (λ) of 405 nm and an output of about 100 to 300 mW. This laser is used for recording and reproducing high-density optical disks such as Blu-ray and HD-DVD. Specifically, an n-type InGaN crystal cladding layer, a GaN / InGaN crystal active layer, a p-type InGaN crystal cladding layer, and an insulating GaN crystal layer are sequentially formed on an n-type GaN substrate (wafer). The layers are stacked by epitaxial growth of metal vapor deposition (MOCVD). At this time, magnesium (Mg) is used for the p-type and silicon (Si) is used for the n-type as the dopant. The active layer has a quantum well structure in which a GaN well layer is sandwiched between InGaN confinement layers.

  In the present embodiment, the individually divided chips are immersed in a solution containing a cyanide compound. The optical semiconductor device manufacturing apparatus shown in FIG. 2 also applies to this embodiment. Therefore, the specific conditions for the dipping process are the same as those in the first embodiment, and will be omitted.

  As in the first embodiment, the optical semiconductor device according to the present embodiment is a passivation film (for example, a non-reflective coating film (antireflection film) that covers the light emitting surface and the light reflecting surface after being immersed in a solution containing a cyanide compound. ) And a reflective film) are formed. However, this embodiment is further different from the first and second embodiments in that the passivation film is immersed in a solution containing a cyanide compound. Note that the processing conditions of the solution for the passivation film are not necessarily the same as the processing conditions shown in the first embodiment. For example, the concentration of the cyanide compound and the type of solvent are appropriately selected.

  In this embodiment, the optical semiconductor device is immersed in a solution containing a cyanide not only before the formation of the passivation film but also after the formation. Thus, for example, when a passivation film is formed by sputtering, impurities such as metals that are inevitably taken into the film are taken out into the solution by forming a complex with cyanide ions. Therefore, the presence of the passivation film according to the present embodiment can significantly reduce the risk that a new surface level or the like is generated on the light exit surface or the like. In addition, the immersion of the optical semiconductor device in the solution after the formation of the passivation film can also contribute to the termination of unbonded hands existing at the interface between the passivation film and the substrate surface such as the light exit surface.

  Although the embodiments of the present invention have been specifically described so far, the above-described embodiments are merely examples for carrying out the present invention. For example, in order to exert the effect of the present invention, the optical semiconductor device does not necessarily need to be immersed in a solution containing a cyanide compound. Specifically, an optical semiconductor device manufacturing apparatus 300 as shown in FIG. 3 (for the sake of convenience, a known optical semiconductor device holding fixture is not shown) is used, and the optical semiconductor device 10 and a solution 22 containing a cyanide compound are predetermined. The solution 22 may be evaporated by storing in the container 34 and heating the container 34 with a heater 36. Thereby, since the optical semiconductor device 10 is exposed to the vapor 32, the same effect as the above-described embodiments is exhibited. At this time, fresh steam 32 is always supplied to the optical semiconductor device 10 by appropriately exhausting from the exhaust pump. Further, using an optical semiconductor device manufacturing apparatus 400 as shown in FIG. 4 (a known optical semiconductor device holding fixture is not shown for convenience), an optical semiconductor device 10 contained in a predetermined container 44 is formed by a sprayer 46. On the other hand, a mist 42 of a solution containing a cyanide may be jetted. In this case, the mist 42 may be the vapor of the solution. For example, even if the mist 42 is about room temperature and does not reach the boiling point of the solution, the mist 42 can be sprayed in the form of a mist. It is effective for. Moreover, if the spray process is employed, the total amount of solution used can be reduced regardless of the temperature of the solution used. On the other hand, the amount of the solution used can be suppressed in the treatment using steam as compared with the immersion treatment in the solution.

  In each embodiment of the present invention, only the state in which the entire optical semiconductor device is completely immersed in the solution containing the cyanide compound in the treatment tank is shown as the “immersion” step. The process is not limited to this. For example, even if a paddle is formed on the target substrate surface, or even if the solution flows (or moves) on the target substrate surface, the surface is Is also covered by “immersion” in the present invention.

  The solute of the solution containing the cyan compound is preferably a non-metallic cyan compound. Even in the case of a metal cyanide compound, the influence of the metal ion is extremely small because the metal ion is taken into the molecule and inactivated by selecting an alcohol as a solvent. However, since it is preferable to remove factors that may adversely affect the optical semiconductor device as much as possible, the non-metallic cyan compound is more suitable as the solute of the solution than the metallic cyan compound.

  Further, as already described, the treatment process with the solution containing the cyanide compound shown in the present embodiment is effective not only for individual optical semiconductor devices but also during the manufacturing process of the devices. . For example, the above-described processing steps are effective even at the stage where a crystal substrate in the process of manufacturing an optical semiconductor device, that is, an insulating film, a doping region, or a wiring constituting this device is formed. Accordingly, the light emitting surface or the light reflecting surface constituting a part of the optical waveguide of the optical semiconductor device, or the passivation film covering them is immersed, sprayed, or exposed to the vapor using the solution. At least one of the effects of the present invention is exhibited.

  Although the mechanism of the effect of the present invention is not necessarily clearly understood, many unbonded hands existing on the surface of the optical semiconductor device or in the vicinity thereof by the treatment using the solution containing the cyanide compound described above. It is considered that (dangling bond) has a large effect of being terminated by a bond of a cyano group (—CN). The bond of the cyano group is very strong, and alteration due to oxidation or the like on the light emitting surface or the light reflecting surface is suppressed. As a result, it is considered that the spread of the non-light emitting portion in the vicinity of these surfaces is suppressed. In addition, when the passivation film comes into contact with a solution containing a cyanide compound, for example, when the passivation film is formed by sputtering, metal impurities inevitably incorporated into the film form a complex with cyanide ions. It is thought that there is an effect brought out in the solution. Further, even if the film is in contact with the solution after the passivation film is formed on the light emitting surface or the light reflecting surface, the passivation film and the light may be used as long as the film is not a dense film that does not pass cyano ions. It can be said that it also contributes to the termination of unbonded hands existing at the interface with the substrate surface such as the emission surface.

  The optical semiconductor device includes not only a light emitting semiconductor device such as a laser but also a light receiving semiconductor device. The present invention is also applied to a light receiving semiconductor device similar to the configuration and manufacturing process shown in each embodiment.

  Further, the present invention is not limited to the semiconductor laser device using the III-V group compound and the manufacturing method thereof shown in each embodiment, but other semiconductors having the same configuration, for example, a II-VI group compound, or a general The present invention is also effective for an optical semiconductor device using a semiconductor nanoparticle having an extremely large influence of the presence of dangling bonds as compared with a semiconductor device and a method for manufacturing the same. Examples of semiconductor nanoparticles to which the present invention is applied include nano-sized silicon, IV group Ge, II-VI group ZnSe, ZnTe, CdSe, CdTe, III-V group InP, GaSb, and the like. is there. The particle size of the semiconductor nanoparticles is not particularly limited, but when expressed numerically, the average particle size is 1 nm or more and 10 nm or less. Further, the surface of the nano-sized silicon can be a light emitting surface or a light reflecting surface.

In the above description of the first embodiment, it has been described that most of the light is reflected and returns to the active layer 3 in the reflective film of the optical semiconductor device 10, but in reality, a part of the light is absorbed, Or it emits outside. Therefore, if there are many unbonded hands and bonds with impurities at the end face where the light reflecting film is formed or at a depth near the end face, unnecessary heat generation is also reduced here in the narrow band gap, similar to the light exit face. It will cause. Therefore, the present invention is very effective not only for the light exit surface but also for the light reflection surface. As described above, the modifications within the spirit and scope of the present invention are also included in the scope of the claims.

  The present invention is used in an optical semiconductor device, a manufacturing method thereof, and a manufacturing apparatus thereof.

It is a schematic block diagram of the optical semiconductor device in one embodiment of this invention. 1 is an optical semiconductor device manufacturing apparatus according to an embodiment of the present invention. It is a manufacturing apparatus of the optical semiconductor device in other embodiments of the present invention. It is a manufacturing apparatus of the optical semiconductor device in other embodiments of the present invention.

Explanation of symbols

1 substrate 2 n-type confinement layer (cladding layer)
3 Active layer 4 p-type confinement layer (cladding layer)
5 Cap layer 6 Insulating film 7 First electrode (anode)
8 Second electrode (cathode)
DESCRIPTION OF SYMBOLS 9 Nonreflective coating film 10 Optical semiconductor device 22 Solution containing cyanide compound 26 Temperature controller 32 Steam of solution containing cyanide compound 36 Heater 24 Treatment tank 34,44 Container 42 Mist of solution containing cyanide compound 46 Nebulizer 200,300, 400 Optical semiconductor device manufacturing apparatus

Claims (15)

An optical semiconductor device in which a substrate surface serving as a light emitting surface or a light reflecting surface is terminated mainly by a cyano group bond. The optical semiconductor device according to claim 1, wherein the surface is a cleaved surface of a crystal, a surface formed by etching, or a surface of semiconductor nanoparticles. The optical semiconductor device according to claim 1, wherein the base material is a compound semiconductor or nanosize silicon. The optical semiconductor device according to claim 1, wherein a passivation layer is formed on the surface. A method of manufacturing an optical semiconductor device, comprising: a step of immersing a substrate surface serving as a light emitting surface or a light reflecting surface in a solution containing a cyanide compound, spraying the solution, or exposing to a vapor of the solution. The method for manufacturing an optical semiconductor device according to claim 5, further comprising a film forming step in which a passivation layer is formed on the surface after the step. The optical semiconductor device according to claim 6, further comprising a step of, after the film forming step, the passivation layer is immersed in a solution containing a cyanide compound, sprayed with the solution, or exposed to vapor of the solution. Production method. 6. The method of manufacturing an optical semiconductor device according to claim 5, wherein the surface is a cleaved surface of a crystal, a surface formed by etching, or a surface of semiconductor nanoparticles. The method of manufacturing an optical semiconductor device according to claim 5, wherein the cyanide compound is a nonmetallic cyanide compound. The method of manufacturing an optical semiconductor device according to claim 5, wherein the base material is a compound semiconductor or nano-sized silicon. An optical semiconductor device manufacturing apparatus comprising means for immersing a substrate surface serving as a light emitting surface or a light reflecting surface in a solution containing a cyanide compound, spraying the solution, or exposing to a vapor of the solution. The surface of the base material that becomes the light emitting surface or the light reflecting surface is immersed in a solution containing a cyan compound, sprayed with the solution, or exposed to the vapor of the solution, and a passivation layer is formed on the surface. An apparatus for manufacturing an optical semiconductor device having means for: The surface of the base material that becomes the light emitting surface or the light reflecting surface is immersed in a solution containing a cyan compound, sprayed with the solution, or exposed to the vapor of the solution, and a passivation layer is formed on the surface. And an apparatus for manufacturing an optical semiconductor device, wherein the passivation layer is immersed in a solution containing a cyanide compound, sprayed with the solution, or exposed to vapor of the solution. The optical semiconductor device manufacturing apparatus according to claim 11, wherein the surface is a cleaved surface of a crystal, a surface formed by etching, or a surface of semiconductor nanoparticles. The optical semiconductor device manufacturing apparatus according to claim 11, wherein the base material is a compound semiconductor or nano-sized silicon.